Device for maintaining metal homeostasis, and uses thereof

Abstract

To satisfy a need to develop novel means of extracting metals from the body, with the aim of preventing and / or treating pathologies related to dysregulation of metal homeostasis.SOLUTION: The present invention relates to the field of medical devices, more particularly to devices for extracting metals from an organism. The use of these devices makes it possible, for example, to prevent and / or treat pathologies linked to dysregulation of metal homeostasis in the organism, for example neurological diseases.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of medical devices, and more particularly to devices for extracting metals from the body. These devices can be used, for example, for the prevention and / or treatment of pathologies associated with dysregulation of metal homeostasis in the body, such as neurological disorders. [Background technology]

[0002] The potentially harmful effects of metals in the body, especially at the neurological level, are being emphasized by a growing body of scientific research (C. Marchetti et al., Biometals, 2014). Chelation therapy, aimed at reducing metal ion concentrations, has been used for many years in cases of acute metal poisoning. Several chelators, each associated with a specific group of metals, have already been tolerated in humans (G. Crisponi et al., Coordination Chemistry Reviews, 2015). Chelation therapy has also proven to be an essential tool in the treatment of transfused patients with β-thalassemia. Patients who receive multiple transfusions suffer from iron accumulation in the body. These iron deposits are regulated by intravenous or oral administration of iron chelators such as desferoxamine, deferiprone, or deferasirox (PV Bernhardt et al., Dalton Trans, 2007). Oral chelation therapy with D-penicillamine and trientine is also currently used to extract copper cations and treat Wilson's disease, which is caused by a genetic defect affecting the copper transporter ATP7B. This defect leads to copper overload, increasing the amount of copper circulating in the blood and resulting in its accumulation in organs, primarily the liver and brain (M.L. Schilsky, Clin. Liver. Dis., 2017). Chelation therapy has good efficacy in presymptomatic treatment, but is less effective in cases of liver or nervous system damage (M. Wiggelinkhuizen et al., Aliment Pharmacol., 2009). This is likely due to difficulty in reaching the target area and poor specificity.

[0003] Unfortunately, chelation therapy is also being misused intravenously to treat a number of other conditions (autism, intermittent claudication, etc.) without prior medical validation. This misuse can result in severe side effects due to excessive dysregulation of essential metal homeostasis in the body, and in the most tragic cases, even death of the patient (G. Crisponi et al., Coordination Chemistry Reviews, 2015).

[0004] A growing body of scientific research highlights the important role that metals, particularly iron, but also copper, zinc, manganese, and even aluminum, play in many neurological disorders (EJ McAllum et al., J. Mol. Neurosci., 2016). This is inevitably an example of an iron overload neurological disorder, a rare disease associated with a genetic defect linked to iron accumulation in certain brain regions, which currently benefits only from palliative treatment (S. Wiethoff et al., Handb. Clin. Neurol., 2017). Furthermore, numerous studies have shown that iron tends to accumulate in the brain with aging (J. Acosta-Cabronero et al., Journal of Neuroscience, 2016). Iron plays a key role in many brain functions, including mitochondrial respiration, myelin and neurotransmitter synthesis, and metabolism (A.A. Belaidi et al., Journal of Neurochemistry, 2016). In the brain, iron is primarily localized in the substantia nigra pars compacta and central gray nucleus, at levels similar to those in the liver. Iron tends to accumulate in certain brain regions with aging, where it is primarily found associated with ferritin and neuromelanin. The areas where iron levels are most likely to increase are the substantia nigra, putamen, globus pallidus, caudate nucleus, or cortex, each of which is associated with different neurodegenerative disorders (DJ Hare et al., Nat. Rev. Neurol., 2015). Several neurological disorders, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, are associated with elevated iron levels in specific regions, which can lead to cellular damage and oxidative stress (AABelaidi et al., Journal of Neurochemistry, 2016). In Parkinson's disease, increased iron levels have been observed in the substantia nigra, a brain region susceptible to parkinsonian pathology. The elevated iron levels are specific to the substantia nigra and do not occur in other areas unaffected by the disease. This elevated iron level can lead to damage following the Fenton reaction, and it has been established that oxidative damage is one of the hallmarks of neurodegenerative diseases (S. Ayton et al., Biomed. Res. Int., 2014).Alzheimer's disease is also characterized by disturbances in brain metal levels, but also in other brain regions and proteins. Indeed, elevated iron levels and decreased copper levels appear to be observed in this case (S.F. Graham et al., J. Alzheimers Dis., 2014). Huntington's disease is another neurodegenerative disorder characterized by motor impairment, cognitive decline, and psychiatric challenges. In this pathology, many markers of oxidative stress are observed in the brain, which may be related to dysregulation of iron homeostasis (S.J.A. van den Bogaard et al., International Review of Neurobiology, 2013). Elevated iron levels in several brain regions (putamen, caudate nucleus, and globus pallidus) have been confirmed by several MRI studies, including that of Bartzorkis and colleagues (G. Bartzorkis et al., Archives of Neurology, 1999).

[0005] Ample evidence regarding the role of dysregulation of iron homeostasis in many neurodegenerative disorders has led scientists to study the impact of chelation therapy on these pathologies (Table 1). For example, deferiprone (used to treat iron deposition during blood transfusions for β-thalassemia) was used in a Phase II clinical trial (DeferipronPD, NCT01539837) involving 22 patients (A. Martin-Bastida et al., Scientific Reports, 2017). Treatment in this trial continued for 6 months and was well tolerated by the patients. Decreases in iron levels were observed in the dentate nucleus and caudate nucleus. Decreases in iron levels in the substantia nigra were observed in only three patients. No changes in iron levels were observed in the globus pallidus or putamen. This trial showed a trend toward improvement in motor scores and quality of life, but the results were not statistically significant. Another clinical trial using deferiprone (Fair-Park I) was conducted by a different team and showed a reduction in iron levels in the substantia nigra and an improvement in motor scores, but this also did not reach statistical significance (G. Grolez et al., BMC Neurology, 2015). Because the results of Fair-Park I were encouraging, the Fair-Park II trial was initiated in 2016 (Table 1). Given the encouraging results of the Parkinson's disease trial, deferiprone was recently proposed for clinical trials in Alzheimer's disease (Table 1). Another metal chelator, clioquinol, had already been tested to study its effect on amyloid fibril formation (Table 1). This drug, banned in the 1970s due to a suspected association with myelooptic neuropathy (C.W.Ritchie et al., Arch. Neurol., 2003), was reevaluated in this study. Although some adverse effects were reported in this study, the safety of this product was considered sufficient for future clinical trials, and clinical benefit was observed in patients most susceptible to the disease. Following this trial, a clioquinol derivative (PBT2) was developed and entered Phase IIa clinical trials (L. Lannfelt et al., Lancet Neurol., 2008).The treatment was well tolerated. Reductions in Aβ protein levels were observed in cerebrospinal fluid, but not plasma. Two measures of executive function also improved in treated patients.

[0006] [Table 1]

[0007] Thus, several iron chelators, such as desferrioxamine, clioquinol, MAO, Vk-28, M30, or M30A (N. Wang et al., Biomacromolecules, 2017), have attracted the attention of researchers in preclinical and even clinical trials for chelation therapy of neurodegenerative diseases. Nevertheless, the efficacy of these and other iron chelators remains limited by their short lifespan in the body, potential cytotoxicity at high doses, difficulty in crossing the blood-brain barrier and targeting to the most affected areas of the brain, and pre-saturation with endogenous cations.

[0008] In parallel with these studies, the National Institutes of Health (NIH) called for clinical trials in 2001 to confirm the benefits of EDTA for the treatment of cardiovascular disease using rigorous scientific protocols. Indeed, it had been claimed in the 1950s that EDTA could chelate calcium from atherosclerotic plaques and cause their dissolution. Due to a lack of clinical results, most cardiologists rejected this practice. Nevertheless, clinicians continued to use it, and by 2007, studies showed that more than 110,000 patients were receiving this treatment annually in the United States. In 2002, the NIH funded the Trial to Assess Chelation Therapy (TACT, NCT, 00044213). This study enrolled 1,708 patients aged 50 years or older who had previously suffered a myocardial infarction for at least 6 months. The trial demonstrated that EDTA therapy was well tolerated in enrolled patients (DBMark et al., Circ. Cardiovasc. Qual. Outcomes, 2014). A modest but significant benefit was observed in patients treated with EDTA (P. Ouyang et al., Curr. Cardiol. Rep., 2015). However, this benefit was much greater in the subgroup of patients with diabetes (633 patients) (E. Escolar et al., Circ. Cardiovasc. Qual. Outcomes, 2014). Diabetic patients treated with EDTA showed a 41% relative risk reduction (p<0.001) for combined cardiovascular outcomes, a 40% reduction (p=0.017) in the risk of nonfatal stroke or nonfatal myocardial infarction, and a 43% reduction (p=0.011) in the risk of death. Thus, this study demonstrates the potential of targeted chelation therapy to prevent future stroke in a specific group of patients, namely those with diabetes.

[0009] Currently, it is also argued that an increasing number of pathologies are related to the dysregulation of metal homeostasis in the body, as has recently been shown for symptoms of cocaine addiction (KDErsche et al., Transl. Psychiatry, 2017) and is suspected for syndromes such as autism (DARossignol et al., Transl. Psychiatry, 2014). Many publications have emphasized the role of iron, which can be visualized by MRI. (i) Manganese in the so-called manganese poisoning neurological syndrome (P. Chen et al., J. Neurochem., 2015), (ii) Copper in cases of Wilson's disease other endogenous metals such as, or (i) Mercury for neurotoxicity and cardiac damage (J. Ohlander et al., Int. J. Occup. Environ. Health, 2016); (ii) Cadmium, for example, in cases of poisoning (VMAndrade, Adv. Neurobiol, 2017), (iii) Lead associated with lead poisoning (G. Björklund et al., Arch. Toxicol., 2017) Exogenous metals such as However, it has been shown that deregulation of these homeostasis due to external factors or genetic abnormalities can cause severe neurological disorders. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] C. Marchetti et al., Biometals, 2014 [Non-patent document 2] G. Crisponi et al., Coordination Chemistry Reviews, 2015 [Non-patent document 3] PV Bernhardt et al., Dalton Trans, 2007 [Non-patent document 4] ML Schilsky, Clin. Liver. Dis., 2017 [Non-Patent Document 5] M. Wiggelinkhuizen et al., Aliment Pharmacol., 2009 [Non-patent document 6] EJMcAllum et al., J. Mol. Neurosci., 2016 [Non-Patent Document 7] S. Wiethoff et al., Handb. Clin. Neurol., 2017 [Non-patent document 8] J. Acosta-Cabronero et al., Journal of Neuroscience, 2016 [Non-Patent Document 9] AABelaidi et al., Journal of Neurochemistry, 2016 [Non-Patent Document 10] DJ Hare et al., Nat. Rev. Neurol., 2015 [Non-Patent Document 11] S. Ayton et al., Biomed. Res. Int., 2014 [Non-Patent Document 12] S.F. Graham et al., J. Alzheimers Dis., 2014 [Non-Patent Document 13] SJA van den Bogaard et al., International Review of Neurobiology, 2013 [Non-Patent Document 14] G. Bartzorkis et al., Archives of Neurology, 1999 [Non-Patent Document 15] A. Martin-Bastida et al., Scientific Reports, 2017 [Non-Patent Document 16] G. Grolez et al., BMC Neurology, 2015 [Non-Patent Document 17] CWRitchie et al., Arch. Neurol., 2003 [Non-Patent Document 18] L. Lannfelt et al., Lancet Neurol., 2008 [Non-Patent Document 19] N. Wang et al., Biomacromolecules, 2017 [Non-Patent Document 20] DBMark et al., Circ. Cardiovasc. Qual. Outcomes, 2014 [Non-Patent Document 21] P. Ouyang et al., Curr. Cardiol. Rep., 2015 [Non-Patent Document 22] E. Escolar et al., Circ. Cardiovasc. Qual. Outcomes, 2014 [Non-Patent Document 23] KDErsche et al., Transl. Psychiatry, 2017 [Non-Patent Document 24] DARossignol et al., Transl Psychiatry, 2014 [Non-Patent Document 25] P. Chen et al., J. Neurochem., 2015 [Non-Patent Document 26] J. Ohlander et al., Int. J. Occup. Environ. Health, 2016 [Non-Patent Document 27] VMAndrade, Adv. Neurobiol, 2017 [Non-patent document 28] G. Bjorklund et al., Arch. Toxicol., 2017 [Non-Patent Document 29] CMKho, Mol. Neurobiol., 2016 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, there is a need today to develop new means of extracting metals from the body for the purpose of preventing and / or treating pathologies associated with dysregulation of metal homeostasis, which would provide one or more of the following advantages: - Target and extract metals from the body whether they are present in large or small amounts. - Regulates essential metal homeostasis. - No cytotoxicity. - No limit to lifespan within the body. - Facilitating crossing of the blood-brain barrier in the treatment of neurological disorders. - Applications that can be adapted to the prevention and / or treatment of any pathology associated with dysregulation of metal homeostasis.

[0012] These and other advantages are described in the disclosure that follows. [Means for solving the problem]

[0013] Therefore, in this context, the inventors of the present invention have developed a medical device comprising at least one chelating agent for extracting metal cations.

[0014] In a first aspect, the present invention relates to a device for maintaining metal homeostasis for therapeutic purposes, characterized in that the device comprises means for extracting metal cations.

[0015] "Maintaining metal homeostasis for therapeutic purposes" means regulating the levels of certain metals in the body, particularly for the purpose of extracting excess metal cations that may be involved in pathology.

[0016] In one embodiment, the term "metal homeostasis" refers to metal cation homeostasis (more specifically, the homeostasis of a particular metal cation).

[0017] In one embodiment, the means for extracting metal cations comprises: - an implant to which at least one chelating agent is grafted, or - Perfusion solution containing at least one chelating agent is selected from.

[0018] According to the present invention, the term "chelating agent" means an organic group capable of complexing with at least one metal cation. According to a preferred embodiment, the chelating agent is capable of complexing with the metal cations that it is desired to extract, and has a complexation constant log(K) of said chelating agent with at least one of said metal cations. C1) is greater than 10, in particular 11, 12, 13, 14, 15, and preferably greater than or equal to 15. Advantageously, the chelating agent is selected from the group consisting of metallic copper (Cu), iron (Fe), zinc (Zn), mercury (Hg), cadmium (Cd), lead (Pb), aluminum (Al), manganese (Mn), arsenic (As), mercury (Hg), cobalt (Co), nickel (Ni), vanadium (V), tungsten (W), zirconium (Zr), titanium (Ti), chromium (Cr), silver (Ag), bismuth (Bi), tin (Sn), selenium (Se), thallium (Th), calcium (Ca), magnesium (Mg), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (S cations, such as ammonium iodide (AIO), ... Even more preferably, the chelating agent complexes with at least one of the cations of the metals copper, iron, zinc, mercury, cadmium, lead, aluminum, manganese, magnesium, calcium, and gadolinium, particularly manganese and gadolinium.Even more preferably, the chelating agent complexes with at least one of the cations of the metals copper, iron, and / or zinc.

[0019] According to the present invention, the term "at least one chelating agent" means a single type of chelating agent, a mixture of different chelating agents, or a mixture of several identical chelating agents.

[0020] Advantageously, the specificity of the chelating agent for the metal (metal cation) to be extracted is high compared to other cationic trace elements, in particular the difference in complexation constant is preferably greater than 3, more particularly the difference in complexation constant with calcium and magnesium is preferably greater than 3, even greater than 5.

[0021] According to a preferred embodiment, the device also contains trace elements selected from calcium, magnesium, iron, copper, zinc and manganese, either directly in the polymer, implant or solid or in the perfusion solution, thereby making it possible to regulate, for example, the homeostasis of essential metals.

[0022] According to a preferred embodiment, said means of said device make it possible to extract metal cations from biological fluids, organs or tissues, in particular when the content of said metal cations is less than 1 ppm, in particular 0.1 ppm, 0.01 ppm, preferably less than 1 ppb, and advantageously to extract more than at least half of the cations present.

[0023] According to the present invention, the term "biological fluid" means any fluid, such as blood, cerebrospinal fluid, synovial fluid, or peritoneal fluid, that the device of the present invention is brought into contact with.

[0024] According to the present invention, the term "organ" means any organ, such as the brain, liver, pancreas, intestine, or lung, that can be contacted with or into which the device of the present invention can be implanted or inserted.

[0025] According to the present invention, the term "tissue" refers to any tissue, such as peritoneum or tumor tissue (if applicable), into which the device of the present invention can be contacted or into which the device of the present invention can be implanted or inserted, for example, said device can be contacted, inserted or implanted by endoscopy, in particular into a tumor.

[0026] According to a preferred embodiment, said means for extracting metal cations is for example a material, making it possible to extract metal cations in an amount corresponding to at least 1% of its mass, preferably more than 10% of its mass.

[0027] The means for metal extraction is a dialysis system. Advantageously, and according to a preferred embodiment, the means for extracting metal cations comprises: a. a porous dialysis membrane; and b. Reservoir containing perfusate A dialysis system including:

[0028] According to the present invention, the term "dialysis system" is any system that allows metal cations to pass through an artificial membrane.

[0029] According to this particular embodiment, the device is advantageously a microdialysis system. For several years, novel technologies (microdialysis) have been developed for local analyte or sample collection or local drug delivery. Microdialysis was developed at the end of the 1950s to recover and deliver various substances in the area of ​​interest (CM Kho, Mol. Neurobiol., 2016). Microdialysis allows for the collection or delivery of only those samples that can pass through a semipermeable membrane, the cutoff threshold of which is chosen according to the intended application. In the case of dialysis, this is often a dynamic diffusion phenomenon driven by the difference in concentration of the diffusing species between the two sides of the membrane. In the case of low concentrations of chemical species, the driving force often quickly becomes limiting or saturated, and the capture of the chemical species of interest is limited by the equilibrium concentration.

[0030] Advantageously, the microdialysis device of the present invention circumvents the problems of conventional chelators by maintaining at least one target metal-complexing species inside the dialysis membrane, allowing for extremely high local extraction of target metal ions. The complexing species is present in a polymer or nanoparticle with a mass greater than the membrane cutoff, so that the complexing species remains in the fluid (i.e., perfusate) within the dialysis membrane. The dialysis device containing the complexing species is then placed in the area of ​​interest, e.g., the brain for the treatment of neurodegenerative diseases.

[0031] Cations smaller than the membrane cutoff can diffuse through the membrane into a solution containing a chelating agent. The strong complexing properties of the ligand used allow the target metal to be chelated even when present in very small amounts. This chelation therefore reduces the concentration of free target ions in the solution inside the membrane, maintaining a strong concentration gradient of the target metal ions between the concentrations outside and inside the membrane, prolonging the extraction time and maintaining the flux of cations. Similar concentrations of these ions may be placed in the dialysis membrane so as not to disturb the homeostasis of other metal cations.

[0032] According to the present invention, any microdialysis device known to those skilled in the art may be used, as long as it comprises a porous dialysis membrane and a reservoir containing a perfusate containing at least one chelating agent as described above. In this respect, the cutoff threshold of the porous membrane is lower than the mass of the chelating agent. By way of example, devices that can be used in connection with the present invention include medical devices developed by M Dialysis AB (Sweden), such as microdialysis catheters (product numbers 8010509, P000049, 8010337; this list is not exhaustive).

[0033] According to this preferred embodiment, the perfusion solution is a colloidal suspension of nanoparticles whose average diameter is larger than the pores of the porous dialysis membrane, and the nanoparticles contain at least one chelating agent as an active ingredient. In one aspect, the cut-off threshold of the porous dialysis membrane is smaller than the mass of the chelating agent, i.e., the mass of the nanoparticles containing at least one chelating agent.

[0034] Alternatively, the perfusion solution is a colloidal suspension of polymers whose average diameter is larger than the pores of the dialysis membrane, the polymers being grafted with an active ingredient which is at least one chelating agent, in which case the cut-off threshold of the porous dialysis membrane is less than the mass of the chelating agent, i.e., the mass of the polymer to which the at least one chelating agent is grafted.

[0035] According to the present invention, the term "colloidal suspension" means a mixture of a liquid and solid, insoluble particles that remain uniformly dispersed, often the particles being small enough (microscopic and submicroscopic) to keep the mixture stable and uniform.

[0036] According to one embodiment, the average diameter is at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% larger than the pores of the dialysis membrane.

[0037] According to the present invention, the term "average diameter" refers to the harmonic mean of the diameters of nanoparticles or polymers to which at least one chelating agent is grafted. The size distribution of nanoparticles or polymers is measured, for example, using a commercially available particle size analyzer, such as a Malvern Zeta Sizer Nano-S particle size analyzer based on photon correlation spectroscopy (PCS), which is characterized by the average hydrodynamic diameter. The method for measuring this parameter is also described in ISO 13321:1996.

[0038] In one embodiment, the colloidal suspension comprises more than 1% by weight of nanoparticles or polymer, in particular more than 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, preferably more than 10% by weight.

[0039] Nanoparticles that can be used in the devices according to the invention, in particular in dialysis systems or implants The nanoparticles that can be used in the present invention have two basic characteristics. They are polysiloxane- or silica-based. They have an average diameter greater than 3 nm and preferably less than 50 nm.

[0040] In one embodiment, the nanoparticles comprise as an active ingredient at least one chelating agent capable of complexing with metal cations, said chelating agent having a complexation constant log(K) with at least one of said metal cations greater than 10, preferably greater than or equal to 15. C1 )

[0041] According to the present invention, the term "silica-based nanoparticles" means nanoparticles characterized by a mass percentage of silica of at least 8%.

[0042] According to the present invention, the term "polysiloxane-based nanoparticles" means nanoparticles characterized by a mass percentage of silicon of at least 8%.

[0043] According to the present invention, the term "polysiloxane" means an inorganic crosslinked polymer consisting of siloxane chains.

[0044] The structural units of the polysiloxane may be the same or different and may be represented by the following formula: Si(OSi) n R 4-n wherein - R is an organic molecule linked to silicon by a Si-C covalent bond, n is an integer from 1 to 4.

[0045] As a preferred example, the term "polysiloxane" includes in particular polymers resulting from the condensation of tetraethylorthosilicate (TEOS) and aminopropyltriethoxysilane (APTES) by a sol-gel process.

[0046] Advantageously, therefore, said nanoparticles are a. polysiloxanes in which the mass proportion of silicon is at least 8% of the total mass of the nanoparticles, preferably 8% to 50% of the total mass of the nanoparticles; b. a chelating agent in a proportion of preferably 5 to 1000, preferably 5 to 100 per nanoparticle; c. If necessary, metal elements complexed to a chelating agent, for example in a ratio of 5 to 100 per nanoparticle, preferably 5 to 20 per nanoparticle. Includes:

[0047] Even more advantageously, said nanoparticles have the following formula (I): Si n [O] m [OH] o [Ch1] a [Ch2] b [Ch3] c [M y+ ] d [D z+ ] e [Gf] f (I) and During the ceremony, n is 20 to 50,000, preferably 50 to 1000, m is greater than n and less than 4n; o is 0 to 2n, Ch1, Ch2, and Ch3 are the same or different and are chelating agents linked to the Si of the polysiloxane by a Si-C covalent bond, a, b, and c are integers from 0 to n, and a+b+c is less than or equal to n, preferably a+b+c is from 5 to 100, for example 5 to 20; M y+ and D z+are the same or different metal cations, y and z are 1 to 6, d and e are integers from 0 to a+b+c, and d+e is less than or equal to a+b+c; Gf are identical or different targeting grafts, each linked to Si by a Si-C bond and resulting from the grafting of targeting molecules, thereby enabling the targeting of the nanoparticles to the desired biological tissue, e.g., tumor tissue, and f is an integer between 0 and n.

[0048] In one embodiment, the nanoparticles usable according to the present invention do not contain metal elements, in other words, in the above definition, the nanoparticles contain only a. (polysiloxane or silica) and b. (chelating agent).

[0049] In one embodiment, the chelating agent complexes with cations of the metals Cu, Fe, Zn, Hg, Cd, Pb, Mn, Al, Ca, Mg, Gd.

[0050] In one embodiment, the chelating agent is one of the following complexing molecules or derivatives thereof, such as, in particular, DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), DO3A-pyridine of formula (I) below,

[0051] [ka]

[0052] EDTA (2,2',2'',2''''-(ethane-1,2-diyldinitrilo)tetraacetic acid), EGTA (ethylene glycol-bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid), BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid), NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid), DOTAGA ((2-(4,7,10-tris ... (carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acid), DFO (deferoxamine), amide derivatives such as DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane) or NOTAM (1,4,7-tetrakis(carbamoylmethyl)-1,4,7-triazacyclononane), and mixed carboxylic acids The nanoparticles are obtained by grafting (covalently bonding) one of polyaminopolycarboxylic acids and their derivatives selected from the group consisting of amide derivatives, phosphonic acid derivatives such as DOTP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonate)) or NOTP (1,4,7-tetrakis(methylenephosphonate)-1,4,7-triazacyclononane), cyclam derivatives such as TETA (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid), TETAM (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetrakis(carbamoylmethyl)), TETP (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetrakis(methylenephosphonate)), or mixtures thereof.

[0053] Preferably, the chelating agent is directly or indirectly covalently linked to the polysiloxane silica of the nanoparticle. The term "indirect" linkage refers to the presence of a molecular "linker" or "spacer" between the nanoparticle and the chelating agent, said linker or spacer being covalently bonded to one of the nanoparticle components.

[0054] According to a preferred embodiment, the nanoparticles have an average diameter of 3 to 50 nm and are polysiloxane-based nanoparticles containing a chelating agent obtained by grafting DOTA, DOTAGA, or DTPA onto the nanoparticles.

[0055] According to a preferred embodiment, said nanoparticles are polysiloxane-based nanoparticles having an average size greater than 20 kDa and less than 1 MDa, and comprising said chelating agent obtained by grafting DOTA, DOTAGA or DTPA onto the nanoparticles.

[0056] In a preferred embodiment, the colloidal suspension containing the nanoparticles also contains a trace element selected from calcium, magnesium, iron, copper, zinc, or manganese.

[0057] The nanoparticles according to the invention can be obtained by the process described in patent application FR1053389.

[0058] Polymers that can be used in devices according to the present invention In another embodiment of the present invention, the nanoparticles described above can be replaced by a polymer, in which case said polymer is grafted to at least one chelating agent.

[0059] According to the present invention, the term "polymer" refers to any macromolecule formed by the covalent arrangement of a large number of repeating units derived from one or more monomers. Polymers preferably used in the present invention are, for example, from the chitosan, polyacrylamide, polyamine, or polycarboxylic acid families. For example, these may be polymers containing amino functional groups, such as chitosan. According to a preferred embodiment, the polymer is biocompatible.

[0060] According to one embodiment, the chelating agent or derivative thereof grafted to the polymer is a polyaminopolycarboxylic acid and its derivatives, in particular chosen from DOTA, DTPA, DO3A-pyridine of formula (I) above, EDTA, EGTA, BAPTA, NOTA, DOTAGA, DFO, DOTAM, NOTAM, DOTP, NOTP, TETA, TETAM and TETP, or mixtures thereof.

[0061] Preferably, the chelator is directly or indirectly covalently linked to the polymer or to a polymer chain of greater than 10 kDa, preferably greater than 100 kDa. The term "indirect" linkage refers to the presence of a molecular "linker" or "spacer" between the polymer and the chelator, said linker or spacer being covalently attached to one of the components of the polymer.

[0062] In one embodiment, the chelating agent or derivative thereof grafted to the polymer will contain a dithiocarbamate functional group.

[0063] According to a preferred embodiment, said polymer to which a chelating agent is grafted is chosen from DPTA-BA grafted chitosan or DFO grafted chitosan.

[0064] In a preferred embodiment, the colloidal suspension containing the polymer also contains a trace element selected from calcium, magnesium, iron, copper, zinc, or manganese.

[0065] Chelating molecules that can be used in devices according to the present invention Alternatively, the perfusion fluid is a solution of chelating molecules, which may have an average diameter larger than the pores of the dialysis membrane, i.e., larger than the cut-off threshold of the membrane in order to be retained in the dialysis membrane fluid, or may have an average diameter smaller than the pores of the porous dialysis membrane, in which case they pass through the pores of the membrane before entering the body and being naturally excreted by the kidneys or liver.

[0066] In this embodiment, the chelating molecule has a complexation constant log(K) with at least one of the metal cations greater than 10, preferably greater than or equal to 15. C1 )

[0067] In this embodiment, the solution of chelating molecules also contains a trace element selected from calcium, magnesium, iron, copper, zinc, or manganese.

[0068] Chelator-grafted implants that can be used in devices according to the present invention Alternatively, the means for extracting metal cations is an implant comprising at least one chelating agent.

[0069] According to one embodiment, the means for extracting metal cations is an implant having at least one chelating agent grafted thereon.

[0070] According to the present invention, an "implant" refers to any element intended to be introduced into the body. This may be a "polymer" or "any other solid" as described herein.

[0071] In this embodiment, the polymers described above can be used in the perfusion solution.

[0072] According to the present invention, the term "any other solid" is not limitative and means ceramic, metallic, composite, solid or porous parts, which may optionally be surface functionalized or not, and which may have various shapes (spherical, tubular, flat, etc.).

[0073] In this embodiment, the implant may be implanted especially temporarily and then removed.

[0074] Preferentially, the implant can be implanted in the brain, liver, pancreas, etc. of the subject to be prevented and / or treated. The implant is absorbable and can be gradually excreted naturally by the body. The implant may contain at least one chelating agent that diffuses slowly in the body, for example, less than 100 mg of chelating molecules released per day, preferably less than 10 mg per day, and / or less than 1% of the total mass per day. The implant may be placed in direct contact with tissue or subcutaneously.

[0075] Alternatively, the implant may be in a reservoir with dialysate in contact with the subject to be treated.

[0076] In a second aspect, the present invention relates to the use of a colloidal suspension as described above, in particular in a device as described above.

[0077] The present invention therefore relates to a colloidal suspension of nanoparticles comprising an active ingredient for therapeutic use, which is comprised in a device for maintaining metal homeostasis comprising a porous dialysis membrane, characterized in that the average diameter of said nanoparticles is larger than the pores of the porous dialysis membrane of said device, advantageously said device being a microdialysis device.

[0078] In one embodiment, the present invention relates to a colloidal suspension of a polymer grafted to an active ingredient for therapeutic use, the colloidal suspension being contained in a device for maintaining metal homeostasis comprising a porous dialysis membrane, the colloidal suspension having an average diameter larger than the pores of the porous dialysis membrane, and the polymer grafted to the active ingredient.

[0079] Advantageously, said device is a microdialysis device.

[0080] In one embodiment, the present invention relates to a method for manufacturing a device comprising: - biological fluids such as blood, cerebrospinal fluid, synovial fluid, or peritoneal fluid; or - organs such as the brain, liver, pancreas, intestines, or lungs, or - Tissues such as peritoneum or tumor tissue 14. A device for maintaining metal homeostasis according to any one of claims 1 to 13, characterized in that it comprises means that allow it to be placed in contact with or embedded in a dialysis membrane.

[0081] According to a preferred embodiment, the present invention relates to the above-described colloidal suspension for use in maintaining metal homeostasis.

[0082] According to another preferred embodiment, the present invention relates to a colloidal suspension as described above for use in the treatment of neurological diseases or brain degeneration, such as Parkinson's disease, Alzheimer's disease, neurodegeneration associated with brain iron accumulation (NBIA, also known as neurodegeneration associated with brain iron overload), Wilson's disease, or Huntington's disease.

[0083] According to another preferred embodiment, the present invention relates to the above-mentioned colloidal suspension for use in the treatment of autism.

[0084] According to another preferred embodiment, the present invention relates to a colloidal suspension as described above for use in the treatment of type II diabetes or cardiovascular disease.

[0085] According to another preferred embodiment, the present invention relates to a colloidal suspension as described above for use in the treatment of tumors.

[0086] In a third aspect, the present invention relates to the use of nanoparticles as described above, in particular in devices as described above.

[0087] In one embodiment, the present invention therefore relates to polysiloxane-based nanoparticles having a diameter greater than 3 nm, preferably less than 50 nm, for therapeutic use in devices for maintaining metal homeostasis, said nanoparticles comprising as active ingredient at least one chelating agent capable of complexing with metal cations, and having a complexation constant log(K C1 ) is greater than 10, preferably greater than or equal to 15. Advantageously, said device is a microdialysis device.

[0088] According to a preferred embodiment, the present invention relates to the nanoparticles described above for use in maintaining metal homeostasis.

[0089] In another preferred embodiment, the present invention relates to nanoparticles as described above for use in the treatment of neurological diseases or brain degeneration, such as NBIA disease, Parkinson's disease, Alzheimer's disease, Wilson's disease, or Huntington's disease.

[0090] In another preferred embodiment, the present invention relates to the aforementioned nanoparticles for use in the treatment of autism.

[0091] In another preferred embodiment, the present invention relates to the nanoparticles described above for use in the treatment of type II diabetes or cardiovascular diseases.

[0092] According to another preferred embodiment, the present invention relates to the nanoparticles described above for use in the treatment of tumors.

[0093] In a fourth aspect, the present invention relates to the use of the polymers described above, in particular in devices such as those described above.

[0094] In one embodiment, the present invention thus relates to a polymer for therapeutic use in a device for maintaining metal homeostasis, said polymer being grafted to at least one chelating agent capable of complexing with metal cations, and having a complexation constant log(K C1 ) is greater than 10, preferably greater than or equal to 15. Advantageously, said device is a microdialysis device.

[0095] According to a preferred embodiment, the present invention relates to the above-mentioned polymers for use in maintaining metal and / or protein homeostasis.

[0096] According to another preferred embodiment, the present invention relates to a polymer as described above for use in the treatment of neurological diseases or brain degeneration, such as NBIA type disease, Parkinson's disease, Alzheimer's disease, Wilson's disease or Huntington's disease.

[0097] According to another preferred embodiment, the present invention relates to the above-mentioned polymers for use in the treatment of autism.

[0098] According to another preferred embodiment, the present invention relates to the polymers described above for use in the treatment of type II diabetes or cardiovascular diseases.

[0099] According to another preferred embodiment, the present invention relates to the polymers described above for use in the treatment of tumors.

[0100] The present invention also relates to a method for extracting metal cations from a subject, comprising administering an implant having at least one chelating agent grafted thereon, or using a perfusion solution comprising at least one chelating agent in a device as described above.

[0101] According to the present invention, the "subject" means a human or animal to whom prevention or treatment is provided.

[0102] The present invention is best illustrated by the following examples and figures, which are intended to clarify the subject matter of the present invention and to illustrate advantageous embodiments, but are in no way intended to limit the scope of the invention. [Brief explanation of the drawings]

[0103] [Figure 1] Figure 1 shows an image obtained at the end of perfusion of MnCl solution. This is a coronal section through the microdialysis membrane (black dots). The enhancement around the membrane corresponds to the presence of Mn (a positive MRI contrast agent). [Figure 2] This image shows a coronal section through the microdialysis membrane (black dots) obtained at the end of perfusion with the nanoparticle suspension. The enhancement around the membrane corresponds to the presence of Mn (a positive MRI contrast agent). [Figure 3] FIG. 1 shows an image corresponding to the difference between the two previous images (shown in FIGS. 1 and 2) and highlighting the decrease in tissue concentration of Mn 2+ (highlighted in the microdialysis probe). [Figure 4] Figure 1 shows an image obtained at the end of perfusion with MnCl solution. This is a coronal section through the microdialysis membrane (black dots). The enhancement around the membrane corresponds to the presence of Mn (a positive MRI contrast agent). [Figure 5] This image was obtained at the end of saline perfusion. This is a coronal section through the microdialysis membrane (black dots). The enhancement around the membrane corresponds to the presence of Mn2+ (a positive MRI contrast agent). [Figure 6] This figure shows an image corresponding to the difference between the two previous images (shown in Figures 4 and 5) and highlighting the absence of a decrease in tissue concentrations of Mn2+ (almost no enhancement in the microdialysis probe). [Figure 7] FIG. 1 shows MRI images of solutions 1, 2, 3, 4, and 5. [Figure 8] FIG. 1 shows the hydrodynamic diameter of the nanoparticles obtained in Example 7. [Figure 9] FIG. 1 shows the hydrodynamic diameter of the nanoparticles obtained in Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0104] [Example] Example 1 Extraction of manganese ions from rodent brains This study was carried out on male Wistar rats (body weight 250 g).

[0105] On day 0, for the insertion of the microdialysis cannula, the animals are anesthetized with gas (2.5% isoflurane under O2 / N2 (80:20)) using the heating mat used during the procedure and recovery phase. Local anesthesia is administered by subcutaneous injection of lidocaine (Xylovet 21.33 mg / mL) (4 mg / kg diluted in 0.9% NaCl, 10 μL / g injection volume) before the skin is incised and the skull is cleaned. After the skin is incised, the skull is cleaned to position a microdrill (<1 mm diameter) for skull puncture. The probe is inserted stereotactically. The dialysis cannula (<500 μm diameter) is gently inserted into the brain at the desired location and depth. After the cannula is positioned, it is applied with a fast-setting resin and screwed into the animal's skull. The wound is then closed by suturing the skin. Before the animal awakens, administer an analgesic (Buprecare) subcutaneously. Repeat administration of the analgesic at 8-12 hour intervals for 2 days after microdialysis probe insertion. To limit dehydration, administer a subcutaneous injection of 0.9% NaCl (approximately 0.5 mL for mice and 5 mL for rats) at the beginning of the procedure. To prevent dry eyes, apply ophthalmic ointment (Liposic) at the beginning of the procedure.

[0106] The MRI spectroscopy and imaging protocol was performed on day 3. The protocol was performed with the animals under gas anesthesia (2.5% isoflurane under O2 / N2 (80:20)) using the heating mat used during the procedure and recovery phase and respiratory management during NMR acquisition. A microdialysis probe (2 mm membrane length, 6 kDa cutoff, CMA Microdialysis AB, Kista, Sweden) was inserted into the microdialysis cannula before the animal was positioned in the MRI (Bruker Biospin, 4.7 Tesla). An MRI surface antenna (Doty Scientific, 8 mm diameter, used for transmission and reception) was positioned on the animal's skull perpendicular to the microdialysis probe. During perfusion of the microdialysis probe, MRI acquisition (T1-weighted flash sequence, 2 ms echo time, 150 ms repetition time, coronal slice, 1 mm slice thickness, 3 min acquisition time) was performed continuously.

[0107] result Example 1A The microdialysis probe was perfused with a 1 mM MnCl2 solution in saline at a flow rate of 10 μL / min for 30 min. The microdialysis probe was then perfused with a suspension of polysiloxane nanoparticles bearing free DOTAGA on their surfaces (28.1 mg diluted in 1 mL of saline and 100 μL of NaOH and HCl to equilibrate to pH 7; i.e., 28.1 mg in a total volume of 1100 μL) at a flow rate of 10 μL / min for 30 min. The polysiloxane nanoparticles used consisted of a polysiloxane matrix to which the cyclic chelator DOTAGA was grafted. These nanoparticles had a hydrodynamic diameter of 11.5 ± 6.3 nm. This size prevented them from passing through dialysis membranes with pore sizes of 2–3 nm.

[0108] The image obtained at the end of the perfusion with the MnCl2 solution is shown in Figure 1, and the image obtained at the end of the perfusion with the nanoparticle suspension is shown in Figure 2. Figure 3, corresponding to the subtraction of the previous two images, shows the intratissue Mn 2+ Images highlighting the concentration decrease (highlighted in the microdialysis probe) are shown.

[0109] Example 1B The microdialysis probe is perfused with a 1 mM MnCl2 solution in saline at a flow rate of 10 μL / min for 30 min. The microdialysis probe is then perfused with saline at a flow rate of 10 μL / min for 30 min. The image obtained at the end of the MnCl2 solution perfusion is shown in Figure 4, and the image obtained at the end of the saline perfusion is shown in Figure 5. Figure 6 shows the difference between the previous two images and shows the Mn 2+ 1 shows images showing the absence of a decrease in tissue concentration of (little enhancement in the microdialysis probe).

[0110] conclusion MRI revealed Mn 2+ The presence of chelating nanoparticles in the perfusate allows for the realization of variations in tissue concentrations of cations (paramagnetic MRI contrast agents). 2+ The reduction in concentration results in a significant decrease in intensity in the MRI cross section, which is not observed in the absence of chelating nanoparticles.

[0111] Example 2 Extraction of gadolinium from tissues by perfusion with nanoparticle solutions This study was carried out on male Wistar rats (body weight 250 g).

[0112] On day 0, for the insertion of the microdialysis cannula, the animals are anesthetized with gas (2.5% isoflurane under O2 / N2 (80:20)) using the heating mat used during the procedure and recovery phase. Local anesthesia is administered by subcutaneous injection of lidocaine (Xylovet 21.33 mg / mL) (4 mg / kg diluted in 0.9% NaCl, 10 μL / g injection volume) before the skin is incised and the skull is cleaned. After the skin is incised, the skull is cleaned to position a microdrill (<1 mm diameter) for skull puncture. The probe is inserted stereotactically. The dialysis cannula (<500 μm diameter) is gently inserted into the brain at the desired location and depth. After the cannula is positioned, it is applied with a fast-setting resin and screwed into the animal's skull. The wound is then closed by suturing the skin. Before the animal awakens, administer an analgesic (Buprecare) subcutaneously. Repeat administration of the analgesic at 8-12 hour intervals for 2 days after microdialysis probe insertion. To limit dehydration, administer a subcutaneous injection of 0.9% NaCl (approximately 0.5 mL for mice and 5 mL for rats) at the beginning of the procedure. To prevent dry eyes, apply ophthalmic ointment (Liposic) at the beginning of the procedure.

[0113] The microdialysis perfusion protocol is performed on day 3. The protocol is performed with the animals under gas anesthesia (2.5% isoflurane under O2 / N2 (80:20)) with respiratory frequency controlled using the heating mat used during the procedure and recovery phase. A microdialysis probe (2 mm membrane length, 6 kDa cutoff, CMA Microdialysis AB, Kista, Sweden) is inserted into the microdialysis cannula and perfusion is performed at a flow rate of 10 μL / min.

[0114] The perfusion is carried out for 30 minutes with a perfusion solution consisting of saline supplemented with 1 mM GdCl3 (solution 1). At the end of the microdialysis, the dialysate is collected (solution 2).

[0115] The microdialysis probe is then perfused for 30 min with a suspension of nanoparticles VL29-5 (28.1 mg diluted with 1 mL saline and 100 μL NaOH and HCl to equilibrate to pH 7, i.e., 28.1 mg in a total volume of 1100 μL) (solution 3). At the end of the microdialysis, the dialysate is collected (solution 4). The nanoparticles used are identical to those in Example 1; they have a hydrodynamic diameter of 11.5 ± 6.3 nm. This size prevents them from passing through dialysis membranes with pore sizes of 2-3 nm.

[0116] These four solutions (as well as saline solution 5) will be imaged using 4.7 Tesla MRI with a T1-weighted gradient echo sequence (repetition time 40 ms, echo time 2.6 ms, tilt angle 80°).

[0117] Images of five tubes are shown in Figure 7.

[0118] result The results in Figure 7 thus highlight the increased intensity of solution 4 compared to solution 5, clearly indicating that tissue Gd uptake and chelation is occurring while the nanoparticle solution is passing through the microdialysis probe.

[0119] Example 3 Synthesis of chitosan-DTPA-BA The chitosan used had an average molecular weight of 200 kDa. DTPA-BA (diethylenetriaminepentaacetic acid dianhydride) was supplied by Chematech, Dijon, France, and used as received. VIVAFLOW cassettes were purchased from Sartorius and used as received. Perfusion fluid (Perfusion Fluid CNS Sterile, product number P000151) was purchased from Phymep and used as received.

[0120] A mass of 0.5 g of chitosan was weighed and placed in a 500 mL container. A volume of 250 mL of distilled water was added and the solution was stirred. The pH was adjusted to 4.0 ± 0.1 using a pH meter and 50% acetic acid solution. The solution was stirred for 24 hours. After 24 hours, the pH was again adjusted to 4.0 ± 0.1. This procedure was repeated until all the chitosan was completely dissolved.

[0121] A mass of 5.36 g of DTPA-BA was weighed and added to the resulting solution. The solution was stirred for 48 hours. After 48 hours, the solution was purified using a Vivaflow cassette with a 100 kDa cutoff until at least 100,000-fold purity was achieved. The solvent was then replaced with the CNS perfusate at the same concentration using a Vivaflow cassette again.

[0122] Example 4 Synthesis of chitosan-DFO The chitosan used had an average molecular weight of 200 kDa. p-NCS-Bz-DFO (N1-hydroxy-N1-(5-(4-(hydroxy(5-(3-(4-isothiocyanatophenyl)thioureido)pentyl)amino)-4-oxobutanamido)pentyl)-N4-(5-(N-hydroxyacetamido)pentyl)succinamide) was purchased from Chematech Mdt and used as received. VIVAFLOW cassettes were purchased from Sartorius and used as received. Perfusion fluid (Perfusion Fluid CNS Sterile, product number P000151) was purchased from Phymep and used as received.

[0123] A mass of 0.5 g of chitosan was weighed and placed in a 500 mL container. A volume of 250 mL of distilled water was added and the solution was stirred. The pH was adjusted to 4.0 ± 0.1 using a pH meter and 50% acetic acid solution. The solution was stirred for 24 hours. After 24 hours, the pH was again adjusted to 4.0 ± 0.1. This procedure was repeated until all the chitosan was completely dissolved.

[0124] 500 mg of p-NCS-Bz-DFO was weighed and added to the resulting solution. The solution was stirred for 48 hours. After 48 hours, the solution was purified using a Vivaflow cassette with a 100 kDa cutoff until a purity level of at least 100,000-fold was reached. The solvent was then replaced with the CNS perfusate at the same concentration using a Vivaflow cassette again.

[0125] Example 5 MetalSorb purification and conditioning Metalsorb FZ, a polyacrylamide polymer containing dithiocarbamate functional groups, was supplied by SNF, France, and used as received. VIVAFLOW cassettes were purchased from Sartorius and used as received. Perfusion fluid (Perfusion Fluid CNS Sterile, product number P000151) was purchased from Phymep and used as received.

[0126] A 50 mL volume of Metalsorb 20% w / w was measured into a 250 mL container. A 150 mL volume of water was added and the solution was stirred for 2 hours. After 2 hours, the solution was purified using a Vivaflow cassette with a 100 kDa cutoff until at least 100,000-fold purification was achieved. The solvent was then replaced with the CNS perfusate at the same concentration using a Vivaflow cassette again.

[0127] Example 6 Use of the materials obtained in Examples 3, 4, and 5 The materials obtained in Examples 3, 4, and 5 above can be advantageously used as a means for extracting metal cations according to the present invention. The solutions can be used directly or by adapting the formulation to form a perfusate, or the polymers may be extracted and solidified to form macroscopic solids that can be implanted.

[0128] Example 7 Synthesis of polysiloxane-EDTA nanoparticles Polysiloxane particles containing EDTA (ethylenediaminetetraacetic acid)-type chelate Si@EDTA were obtained by mixing three silane precursors: (i) TEOS (tetraethyl orthosilicate) (Si(OC2H5)4, 98% - Sigma Aldrich Chemicals, France), (ii) APTES (3-(3-aminopropyl)triethoxysilane - (H2N(CH2)3-Si(OC2H5)3, 99% - Sigma Aldrich Chemicals, France), and (iii) Si-EDTA (N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid trisodium salt - (N-[3-trimethoxysilylpropyl]ethylenediaminetriacetic acid trisodium salt, 45% in water, ABCR, Germany). The three precursors were mixed in a molar ratio of 2:1:3 (TEOS / APTES / Si-EDTA) with DEG (diethylene glycol - DEG, 99% - SDS Carlo). The mixture is kept under stirring at room temperature for 30 minutes, then three volumes of water are added and stirred again for 17 hours at the same temperature. The temperature is then raised to 80°C and stirring is maintained for 6 hours (after 2 hours of heating, the pH is adjusted to a value of 7.4). The heating is then stopped and the solution is kept under stirring for 17 hours. The solution is then purified by tangential flow filtration. The nanoparticles have a hydrodynamic diameter of 21±9 nm by dynamic light scattering (DLS) using a Malvern Zeta Sizer Nano-S particle size analyzer based on PCS (Figure 8).

[0129] Example 8 Synthesis of polysiloxane-DTPA nanoparticles Nanoparticles containing DTPA (diethylenetriaminepentaacetic acid)-type chelates require a preliminary step of grafting the chelate to a silane. DTPA-containing silanes are obtained by reacting DTPA derivative DTPA-BA (diethylenetriaminepentaacetic acid dianhydride—CheMatech, Dijon, France) with APTES in a 1:1 DTPA-BA / APTES ratio in DEG. The solution is left under stirring for 24 hours. TEOS is then added in a TEOS / APTES / DTPA-BA ratio of 3:1:1. After stirring in DEG for 1 hour, water is added (10 times the volume of DEG used). The solution is then stirred at room temperature for 24 hours, heated to 50°C, and stirred again for 24 hours. Finally, the solution is cooled to room temperature and left under stirring for 72 hours. The nanoparticles are then purified by tangential flow filtration, and the pH is raised to 7.4. The nanoparticles have a hydrodynamic diameter of 7±3 nm by DLS as assessed using a Malvern Zeta Sizer Nano-S particle size analyzer based on PCS, with the second population having a diameter of 20±7 nm (FIG. 9).

[0130] Example 9 Comparison of microdialysis flow rates in the extraction of metals. In this example, the extraction performance of perfusates containing chelating agents in a microdialysis device from aqueous solutions containing several metal ions was compared.

[0131] Several flow rates (1, 2, and 5 μL / min) were tested using the same perfusate (polysiloxane-EDTA nanoparticles, the synthesis of which is described in Example 8, with 15 mM EDTA dispersed in water). The microdialysis membrane (63 Microdialysis Catheter, M Dialysis AB, Sweden) had a cutoff of 20 kDa. The solution used to test the chelating ability of the perfusate was an aqueous solution containing Al(III), Cd(II), Zn(II), Cu(II), and Pb(II) ions at concentrations of 100 ppb each. The pH of the solution was adjusted to 7.4, and HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, Sigma-Aldrich Chemicals, France) was added as a buffer at a concentration of 1.2 g / L. The total volume of the solution was 600 mL.

[0132] Extraction by microdialysis required 40 min at flow rates of 2 and 5 μL / min. Samples at 1 μL / min were obtained at 100 min. These samples were analyzed by ICP / MS, and the amounts of each metal are reported in Table 2. This experiment was performed four times, and shows better extraction of each metal under all conditions tested using perfusates based on chelating nanoparticles compared to conventional microdialysis, where the perfusate initially contained only water (HO). When perfusates containing chelating agents were used, uptake of metals at concentrations exceeding their "diffusion concentration" in the medium to be purified was observed. Chelation is particularly effective in the case of aluminum due to its small size, which allows for faster diffusion through the membrane. A flow rate of 2 μL / min seemed to be a good compromise between efficient extraction and sample volume and was chosen for Examples 10 and 11.

[0133] [Table 2]

[0134] Example 10 Comparison of polysiloxane-DTPA and polysiloxane-EDTA nanoparticle-based perfusates The relative efficiencies of the nanoparticles obtained in Examples 7 and 8 were compared using a 20 kDa cutoff microdialysis membrane, a microdialysis flow rate of 2 μL / min, a 40-minute sampling time, and the same metal mixture as described in Example 9. Table 3 summarizes the results obtained using three different perfusates: (i) water, (ii) polysiloxane-EDTA nanoparticles, and (iii) polysiloxane-DTPA nanoparticles, at a 15 mM chelator concentration. DTPA-based nanoparticles have a very high aluminum extraction capacity due to the very high affinity of the chelator for aluminum. The presence of aluminum appears to saturate the surface chelator, reducing the efficiency of the perfusate for other metals. Polysiloxane-DTPA nanoparticles allow for a perfusate with very high specificity for aluminum extraction.

[0135] [Table 3]

[0136] Example 11 Use of polysiloxane-EDTA nanoparticles as a perfusion fluid for cerebrospinal fluid (CSF) A solution containing NaCl (147 mM), KCl (2.7 mM), CaCl2 (1.2 mM), and MgCl2 (0.85 mM) was synthesized to model CSF. Metal extraction was performed using this solution to confirm that the extraction power was not reduced by various potentially interfering ions. A solution similar to that in Example 9 (i.e., 600 mL of reconstituted CSF containing 100 ppb each of Al(III), Cd(II), Zn(II), Cu(II), and Pb(II)) was prepared. The microdialysis membrane (63 Microdialysis Catheter, M Dialysis AB, Sweden) used had a 20 kDa cutoff, the flow rate was set at 2 μL / min, and the collection time was 40 min. The extracted metal amounts were analyzed by ICP-MS. The perfusate consisted of either reconstituted CSF or polysiloxane-EDTA nanoparticles dispersed in reconstituted CSF, the synthesis of which is described in Example 7. The extraction results are shown in Table 4. It is noteworthy that the extraction capacity of the perfusate containing only CSF was extremely low. The addition of nanoparticles to the perfusate significantly increased the extraction of metals, regardless of the metal. Under these conditions, metal extraction folds of greater than 5 for lead, greater than 7 for copper, greater than 25 for cadmium, and greater than 125 for aluminum were obtained.

[0137] [Table 4]

Claims

[Claim 1] 1. A device for maintaining metal homeostasis for therapeutic purposes, characterized in that it comprises means for extracting metal cations, said means comprising, in particular: an implant comprising at least one chelating agent; or A perfusion solution containing at least one chelating agent included in a dialysis system A device for maintaining metal homeostasis selected from:

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