Drug delivery system based on combination of biodegradable magnesium alloy stent and double-J tube

Abstract

The invention belongs to the field of bladder cancer treatment, and particularly relates to a drug delivery system based on combination of a biodegradable magnesium alloy stent and a double-J tube. The system comprises a biodegradable magnesium alloy stent and a double-J tube, the surface of the biodegradable magnesium alloy stent is modified by a calcium phosphate coating to form a fine needle-shaped micro-nano structure, and the biodegradable magnesium alloy stent loads an anti-cancer drug oridonin. The biodegradable magnesium alloy stent loaded with oridonin is accurately attached to a tumor part by means of ultrasonic guidance, and the double-J tube and the biodegradable magnesium alloy stent are combined for use. According to the invention, the loading efficiency of the hydrophobic drug is improved through the modification of the micro-nano structure of the calcium phosphate coating, and the anti-tumor effect of the magnesium degradation product is cooperated, so that the problems of high frequency, high toxicity and poor compliance of traditional bladder cancer perfusion treatment and difficulty in delivery of Ori and other natural drugs are solved, and finally, accurate, long-acting and low-toxicity treatment of bladder cancer is realized.

Description

Technical field:

[0001] The present invention belongs to the field of bladder cancer treatment, and specifically relates to a drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube. Background technology:

[0002] Bladder cancer is a common tumor of the urinary system, ranking 9th in the world's cancer incidence. It is estimated that by 2040, the number of new cases and deaths from bladder cancer worldwide will increase to 991,000 and 397,000 respectively, posing a serious threat to human health. [1,2] Currently, transurethral bladder tumor resection and postoperative intravesical chemotherapy are the main interventions for the treatment of bladder cancer. [3] . For example, when gemcitabine is used for postoperative intravesical instillation therapy, it is usually started immediately after surgery, initially once a week for 8 consecutive weeks; later it is adjusted to once a month for 10 months, and the total duration of the entire treatment process is up to 1 year. However, this high-frequency operation requires patients to be repeatedly intubated, which not only increases the risk of urethral injury and infection, but also has poor patient compliance; furthermore, due to serious adverse reactions and drug resistance problems after chemotherapy, nearly half of bladder cancer patients will relapse or metastasize within five years after treatment, resulting in poor overall efficacy. Therefore, the development of new, safe, efficient and patient-compliant treatment strategies is a major issue that needs to be urgently addressed in the current field of bladder cancer treatment.

[0003] Oridonin (Ori) is a natural active substance of the enantio-kaurane diterpenoids isolated from the natural plant Oridonium rubescens. It has strong anticancer activity against a variety of malignant tumors, including bladder cancer. [4] At the same time, this small molecule monomer substance has obvious advantages such as low toxicity and side effects, high safety and unique efficacy. It can synergistically improve the treatment effect and prolong the life of cancer patients. It is known as the second most active anti-tumor biological component after paclitaxel. [5] However, due to its own structure, it has poor water solubility, low bioavailability, and difficulty in oral absorption, which greatly hinders its further clinical application. [6] .

[0004] As an economical new biomedical metal material, magnesium alloy has many excellent properties. [7] . Such as: rich resources, low cost; excellent mechanical properties; as a non-trace element necessary for the human body, it participates in a variety of physiological activities, is easily absorbed and excreted by the human body, and shows good biocompatibility. Especially in the treatment of tumors, magnesium alloy materials show unique advantages. When magnesium metal is implanted into the human body and comes into contact with body fluids, the chloride ions and acid ions in the body fluids will corrode it, forming magnesium ions (Mg 2+), hydrogen (H2) and magnesium hydroxide (Mg(OH)2), which can inhibit tumor growth from multiple angles and worsen the microenvironment of tumor cells. 2+ It can inhibit the proliferation, invasion and metastasis of tumor cells, as well as their DNA replication and repair through various mechanisms, thereby exerting anti-tumor effects [8] Wolf et al. found that magnesium deficiency can inhibit the proliferation of HC11 cells by upregulating the expression of cell cycle inhibitory protein p27 and downregulating the expression of cyclinD1; the upregulation of p27 expression is related to the extracellular Mg 2+ The concentration was positively correlated and time-dependent; while the Mg concentration higher than the physiological concentration 2+ Can downregulate p27 and upregulate cyclinD1 expression [9] . Castiglioni et al. also obtained similar results in animal experiments. The tumors developed by magnesium-deficient mice were less vascularized and angiogenic than those in the control group. Since angiogenesis is a key factor in promoting tumor spread, a low magnesium environment can delay the proliferation, migration and differentiation of endothelial cells in vitro, so a low magnesium state can inhibit tumor growth. Therefore, for mice with implanted tumors and solid tumors, the tumor growth rate of the experimental group with a low magnesium diet was significantly lower than that of the control group with normal feeding, but the tumor's ability to metastasize was stronger than that of the control group. When the diet of the experimental group of mice returned to normal, the tumor growth rate increased rapidly.

[10] In addition to the direct anti-tumor effects mentioned above, Mg 2+ It can also indirectly affect the occurrence and development of tumors by regulating the immune system and inflammatory response. 2+ Deficiency can lead to an exacerbation of the inflammatory response, including activation of leukocytes and macrophages, promotion of the release of inflammatory cytokines (such as TNFα, IL-1 and IL-6) and acute phase proteins, and excessive production of free radicals, which together enhance the metastatic ability of cancer cells. 2+ It can significantly reduce the levels of these inflammatory biomarkers and improve the overall function of the immune system, thereby enhancing the body's defense against tumors. [11,12] Therefore, based on its degradation behavior and good biocompatibility, it can be used as an ideal anticancer drug carrier, synergistically exerting anti-tumor efficacy with chemotherapy drugs, providing more accurate, effective and safe treatment for cancer patients, and opening up new possibilities for personalized medicine and precision treatment.

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[0009] [5] Gao Shiyong, Tang Boqi, Wei Xinrui, et al. Herbal research, chemical composition, pharmacological effects and clinical application of Rubescens rubescens[J]. Chinese Herbal Medicine, 2023, 54(19): 6543-6554.

[0010] [6] Guan Xin, Yang Liqiang, Xu Weijie, et al. Research progress on long non-coding RNA in the occurrence and development of bladder cancer[J]. Chinese Journal of Gerontology, 2022, 42(17): 4383-4387.

[0011] [7] Yanbin Zhao, Xueyang Chen, Shuoqi Li, et al. Corrosion resistance and drug release profile of gentamicin-loaded polyelectrolyte multilayers on magnesium alloys: Effects of heat treatment [J]. J Colloid Interface Sci, 2019, 547: 309-317.

[0012] [8]ZHANG Y,YU W,BA Z,et al.3D-printed scaffolds of mesoporousbioglass / gliadin / polycaprolactone ternary composite for enhancement ofcompressive strength,degradability,cell responses and new bone tissueingrowth [J].Int J Nanomedicine,2018,13:5433-5447.

[0013] [9]WOLF FI, MAIER JA, NASULEWICZ A, et al. Magnesium and neoplasia: from carcinogenesis to tumor growth and progression or treatment [J]. ArchBiochem Biophys, 2007, 458(1): 24-32.

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[10] CASTIGLIONI S,MAIER J A.Magnesium and cancer: a dangerous liason[J].Magnes Res, 2011, 24(3):S92-100.

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[11] COSTANTINO MD, SCHUSTER A, HELMHOLZ H, et al. Inflammatory response to magnesium-based biodegradable implant materials [J]. ActaBiomater, 2020, 101: 598-608.

[0016]

[12] LIU ZQ,SHANG LL,GE S H.Immunomodulatory effect ofdimethyloxallyl glycine / nanosilicates-loaded fibrous structure on periodontalbone remodeling[J].J Dent Sci, 2021,16(3):937-947.

[0017] At present, the patents for magnesium-based alloy anti-tumor are as follows: (1) Publication No.: CN116254445A, Wang Leyun et al. developed a method for preparing a ternary magnesium alloy of Mg-Al-Ca and its use as an anti-tumor implant material or magnetic hyperthermia medium. The magnetic heating of the Mg-Al-Ca alloy wire, combined with its faster degradation rate, can inhibit the growth of large-diameter tumors, and its tumor inhibition effect is significantly better than that of pure magnesium. (2) Publication No.: CN119112432A, Zhang Tao invented a magnesium alloy balloon-expandable esophageal stent based on microsphere drug-loaded technology, which has solved the problem that the existing anti-displacement method of the esophageal stent causes damage to the inner wall of the esophagus and the low degree of adhesion between the stent and the esophageal wall. It also solves the problem that the material of the esophageal stent is mostly nickel-titanium alloy, which is a non-degradable material and difficult to remove later, and the secondary effects on the esophageal tissue. (3) Publication No.: CN106310372A, Pei Jia et al. prepared a degradable magnesium-based bone implant drug-carrying polymer calcium-phosphorus composite coating and its preparation, specifically referring to a composite coating in which a drug-carrying degradable polymer coating is sequentially modified on the surface of the bone implant magnesium and magnesium alloy and a bioactive calcium-phosphorus layer is continuously deposited on the surface of the polymer coating, solving the problem that the current bioactive calcium-phosphorus coating cannot effectively carry drugs, and adding a layer of polymer drug carrier coating between the bioactive calcium-phosphorus coating and the substrate.

[0018] The shortcomings of the existing technology are:

[0019] 1. The high invasiveness and low compliance of existing bladder cancer treatments

[0020] Traditional transurethral bladder tumor resection combined with postoperative intravesical chemotherapy (such as gemcitabine) requires high-frequency catheterization operations (up to 1 year), which increases the risk of urethral injury and infection in patients. In addition, due to adverse reactions and drug resistance of chemotherapy drugs, nearly half of patients will relapse or metastasize within 5 years, and the therapeutic effect is poor.

[0021] 2. Bottlenecks limiting the clinical application of Ori

[0022] Although Ori has significant anti-bladder cancer activity and safety advantages, its inherent defects of poor water solubility, low bioavailability and difficulty in oral absorption have seriously hindered its clinical transformation and application.

[0023] 3. Limitations of existing magnesium alloy support technology

[0024] Existing magnesium alloy anti-tumor patents (such as publication numbers CN116254445A and CN119112432A) mostly focus on alloy composition optimization or single device design (such as esophageal stents), and lack a degradation-rate-controllable drug delivery system for local treatment of bladder cancer. Traditional calcium-phosphorus coatings (such as CN106310372A) rely on a polymer intermediate layer for drug delivery, which has a complex process and limited drug loading, making it difficult to achieve rapid drug release and a synergistic anti-tumor effect of degradation products.

[0025] 4. Gaps in precision drug delivery and synergistic therapy

[0026] Currently, there is a lack of a technical solution that can simultaneously meet the following requirements: precisely control the degradation rate of magnesium alloys through surface modification to avoid sudden drug release or premature carrier failure due to rapid degradation; directly increase the loading capacity and release kinetics of hydrophobic drugs (such as Ori) by utilizing the coating micro-nanostructure; and integrate drug carriers with urinary stents (such as double-J tubes) to achieve lesion-targeted implantation and multi-mechanism synergistic treatment of drug-magnesium degradation products. Summary of the invention:

[0027] The purpose of the present invention is to provide a drug delivery system based on a biodegradable magnesium alloy stent combined with a double J tube, to develop a biodegradable magnesium alloy drug-loaded stent system with high drug loading capacity, controllable degradation and clinical operation convenience, to improve the loading efficiency of hydrophobic drugs by modifying the micro-nanostructure of the calcium-phosphorus coating, to synergize the anti-tumor effect of magnesium degradation products, to solve the problems of high frequency, high toxicity, poor compliance and difficulty in delivering natural drugs such as Ori in traditional bladder cancer perfusion treatment, and ultimately to achieve precise, long-term and low-toxicity treatment of bladder cancer.

[0028] The technical solution of the present invention:

[0029] A drug delivery system based on a biodegradable magnesium alloy stent combined with a double-J tube. The system includes a biodegradable magnesium alloy stent and a double-J tube. The surface of the biodegradable magnesium alloy stent is modified with a calcium-phosphorus coating to form a fine needle-like micro-nanostructure. The biodegradable magnesium alloy stent is loaded with the anticancer drug oridonin.

[0030] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube is characterized in that the main part of the double-J tube is placed in the ureter, one end of the double-J tube is inserted into the renal pelvis, the curled structure at one end of the double-J tube is placed in the renal pelvis of the kidney, and the other end of the double-J tube is fixed to the bladder, and the curled structure at the other end of the double-J tube is located in the bladder. After urine is drained from the renal pelvis to the bladder through the double-J tube, it is normally stored and excreted from the body. With the help of ultrasound guidance, the biodegradable magnesium alloy stent loaded with oridonin is precisely fitted to the tumor site, thereby realizing the combination of the double-J tube and the biodegradable magnesium alloy stent.

[0031] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube, for lesions within the bladder, places the biodegradable magnesium alloy stent on the surface of the bladder tumor through the end of the double-J tube, releasing oridonin and magnesium ions to synergistically inhibit the tumor; for lesions at the ureteral opening, the biodegradable magnesium alloy stent is placed along the double-J tube in the lower part of the ureter, supporting the ureter and locally treating the tumor.

[0032] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double J tube is a 3D stent. A surface calcium-phosphorus coating modification technology is used to form a fine needle-shaped micro-nanostructured calcium-phosphorus coating on the surface of the biodegradable magnesium alloy stent. The fine needle-shaped structure is composed of uneven nano-sized needle-shaped crystals, and a nanopore structure is formed between the needle-shaped crystals.

[0033] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double J tube has a fine needle structure with a diameter ranging from 150 to 650 nm, a length ranging from 2 to 15 μm, and a calcium-phosphorus coating with a thickness of 1 to 20 μm.

[0034] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube comprises a fine needle-shaped micro-nanostructured calcium phosphate coating composed of uneven nano-sized needle-shaped crystals, and a nanopore structure is formed between the needle-shaped crystals. Oridonin is loaded into the nanopores of the calcium phosphate coating, and the drug loading concentration is 5 to 20 μM.

[0035] The drug delivery system based on the biodegradable magnesium alloy stent combined with the double J tube, the calcium phosphate coating can significantly improve the corrosion resistance of the magnesium alloy, achieve precise control of the degradation rate of the magnesium metal, and reduce the corrosion rate of the magnesium alloy to 2-4 mm·a -1 .

[0036] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube is integrated with the biodegradable magnesium alloy stent and the double-J tube and then directly implanted into the tumor lesion, thereby achieving efficient and precise drug delivery.

[0037] The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube, the degradation products of the biodegradable magnesium alloy stent include magnesium ions, hydrogen and magnesium hydroxide, and these degradation products synergistically exert anti-tumor effects with the anticancer drug oridonin.

[0038] The design idea of ​​the present invention is:

[0039] The present invention is a degradable magnesium alloy 3D stent that uses surface calcium-phosphorus coating modification technology (publication number: CN118531384A) to significantly improve the corrosion resistance of magnesium alloy and achieve precise control of the degradation rate of magnesium metal. The surface of the modified stent presents a uniform, dense and fine needle-shaped micro-nanostructure, which provides a larger specific surface area, increases the drug loading by up to 300%, and promotes the dissolution and diffusion of the drug, thereby improving the release kinetics of the drug, which is particularly suitable for drugs that require rapid release or targeted release. With the release of the drug and the continuous degradation of the magnesium alloy, the magnesium alloy degradation products and the drug will synergistically exert an anti-tumor effect. This innovative design integrates the stent with the double J tube stent, allowing the system to be directly implanted into the tumor lesion, achieving efficient and precise drug delivery, and effectively solving the problems of poor drug solubility and low bioavailability in traditional treatments. This innovation not only improves the treatment effect, but also brings more convenient and efficient medical solutions to patients.

[0040] The present invention integrates a magnesium alloy stent with a double-J tube, using ultrasound guidance to precisely fit the tumor site, achieving efficient and accurate drug delivery, and utilizing the synergistic effect of magnesium alloy degradation products and drugs to exert anti-tumor effects. The degradation rate of the magnesium alloy stent is controllable, maintaining a physiological pH range, and avoiding sudden drug release or premature failure of the carrier due to excessive degradation. The integrated "double-J tube + drug stent" design reduces the patient's treatment burden, improves treatment compliance, and achieves precise, long-term, and low-toxic treatment for bladder cancer, providing bladder cancer patients with a more effective and safer treatment option.

[0041] The advantages and beneficial effects of the present invention are:

[0042] 1. Low Market Cost: China is one of the countries with the richest magnesium reserves in the world, possessing abundant magnesium ore resources. Its reserves and production occupy a significant position globally. In 2023, my country's primary magnesium production reached 822,400 tons, accounting for 82.24% of the global total. China's abundant magnesium reserves and strong production capacity give it a key position in the global magnesium market, significantly impacting global magnesium supply. These abundant resources also lay a solid foundation for the development of the magnesium alloy industry. In 2023, the price of magnesium ingots in China generally showed a downward trend, fluctuating at a low level. At the beginning of the year, the price of magnesium ingots was 21,600 yuan / ton, but by the end of the year, it had fallen to 20,200 yuan / ton, showing a clear downward trend. Although there was a brief rebound during the year, the price of magnesium remained in a downward trend overall. The abundant reserves and low price of magnesium raw materials laid the material foundation for its further development and utilization.

[0043] 2. Wide scope of application: The present invention is suitable for patients with NMIBC combined with ureteral obstruction (traditional stents have no therapeutic function); high-risk NMIBC patients who have failed BCG treatment (providing an alternative solution); MIBC patients undergoing neoadjuvant chemotherapy (reducing the dose of systemic chemotherapy); and the treatment of patients with postoperative recurrence or metastasis of bladder cancer, and patients with the risk of ureteral obstruction or vesicoureteral reflux.

[0044] 3. The device is easy to operate: For bladder cancer patients who have difficulty urinating due to tumors blocking the ureters, it is only necessary to use ultrasound guidance to precisely fit the biodegradable magnesium alloy stent loaded with Rubescensine A to the tumor site based on the conventional double-J tube implantation (one end of the double-J tube is placed into the renal pelvis through the urethra and the other end is fixed to the bladder). The degradation rate of the stent is regulated by the calcium-phosphorus coating, achieving a synergistic effect of sustained drug release and the anti-tumor effect of magnesium ions, and the patient can urinate normally during treatment. After the tumor is eliminated, the stent is removed together with the double-J tube. There is no need for repeated surgery or perfusion operations throughout the process. It is especially suitable for patients who receive palliative treatment and require long-term catheterization after surgery. It can achieve dual control of the degradation rate of magnesium alloy and drug release, and also play a synergistic role with the drug to achieve the purpose of mildly and effectively inhibiting tumor growth.

[0045] 4. Compared to patent publication number CN116254445A, which covers magnesium alloys and their use as anti-tumor implant materials or magnetic hyperthermia media, this invention focuses on the treatment of bladder cancer. By combining a biodegradable magnesium alloy stent with a double-J stent and incorporating calcium-phosphorus coating modification technology, it achieves precise drug delivery to bladder cancer lesions. This design ensures that the drug acts directly at the tumor site, increasing drug concentration and minimizing the impact on surrounding normal tissue, thereby achieving precise treatment.

[0046] 5. Compared with the patent CN119112432A on magnesium alloy balloon expandable esophageal stent based on microsphere drug loading technology, the present invention utilizes a degradable magnesium alloy stent loaded with Rubescensine A and combines it with a double J tube to precisely deliver the drug to bladder cancer lesions. The magnesium alloy degradation products synergistically exert anti-tumor effects with the drug, such as Mg 2+ , H2 and OH- and other degradation products inhibit tumor cell proliferation, promote apoptosis and alkalize the tumor microenvironment, and enhance the therapeutic effect together with oridonin.

[0047] 6. Compared with the patent for biodegradable magnesium-based bone implant drug-loaded polymer / calcium-phosphorus composite coating and its preparation, the present invention solves the core problems of the existing technology, such as low drug loading efficiency, asynchronous degradation and drug release, and poor organ adaptability, through four innovations: replacing the multi-layer structure with a single-layer micro-nano coating, omitting the polymer drug-loaded intermediate layer, bladder-specific device design, and drug-metal ion synergistic mechanism. Description of the drawings:

[0048] Figure 1 This is a schematic diagram of a drug delivery system for a biodegradable magnesium alloy stent coated with calcium phosphate combined with a double-J tube for the treatment of human urothelial carcinoma. (a) is an overall diagram of the drug delivery system, (b) is an enlarged view of the biodegradable magnesium alloy drug-eluting stent in (a), (c) is a partial enlarged view of (b), (d) is a partial enlarged view of the calcium phosphate coating in (c), and (e) is the chemical formula structure of the drug on the coating in (c). Figure numerals: 1-double-J tube, 2-biodegradable magnesium alloy stent, 3-renal pelvis, 4-kidney, 5-ureter, 6-bladder, 7-calcium phosphate coating, 8-oridonin.

[0049] Figure 2 The pH value of the magnesium alloy modified with calcium-phosphorus coating in artificial urine changes. In the figure, the horizontal axis Time is time (days) and the vertical axis is pH value.

[0050] Figure 3 The corrosion rate of magnesium alloy modified with calcium phosphorus coating in artificial urine is shown in the figure. The horizontal axis Time is time (Days) and the vertical axis Cprrosion rate is the corrosion rate (mm·a -1 ), pure Mg is pure magnesium, Mg Ca-P calcium phosphorus coating modified magnesium alloy.

[0051] Figure 4 This is the scanning electron microscopy (SEM) characterization of the magnesium alloy modified with the calcium-phosphorus coating. The immersion time in artificial urine was 6h, 1D, 3D, 7D, and 14D, respectively. The upper figure is the SEM image of the magnesium alloy without calcium-phosphorus coating after immersion, and the lower figure is the SEM image of the magnesium alloy with calcium-phosphorus coating after immersion.

[0052] Figure 5 The drug release curve is shown in FIG. 1 , where the horizontal axis Time represents time (h) and the vertical axis Drug Release represents the drug release rate (%).

[0053] Figure 6 The effect of magnesium alloy combined with Ori bladder cancer cell proliferation activity. In the figure, the horizontal axis Time is time (h), and the vertical axis Relative cell viability is the relative cell viability (%).

[0054] Figure 7 The effect of magnesium alloy combined with Ori on the proliferation of bladder cancer cells. (a) is a fluorescence microscope image of EdU fluorescence staining to detect cell proliferation. Hoechst 33342 represents nuclear staining (blue fluorescent marker), EdU represents newly synthesized DNA (green fluorescent marker), Merge represents the overlay of Hoechst and EdU, Control represents the untreated group, DMSO represents the dimethyl sulfoxide-treated group, Ori represents the oridonin-treated group, Mg represents the pure magnesium-treated group, and Ori+Mg represents the oridonin- and pure magnesium-treated group. (b) is a quantitative statistical graph of EdU staining. The horizontal axes are Control, DMSO, Ori, Mg, and Mg+Ori, respectively. The vertical axis, EdU-positive cells, represents the percentage (%) of cells that have taken up and incorporated EdU (5-ethynyl-2'-deoxyuridine) during cell proliferation.

[0055] Figure 8 The effect of magnesium alloy combined with Ori on the apoptosis of bladder cancer cells. In the figure, the horizontal axis is Annexin V-FITC, an early apoptosis marker, and the vertical axis is PI, a cell necrosis / late apoptosis marker.

[0056] Figure 9 This is a model diagram of the biodegradable magnesium-based alloy drug delivery system. Specific implementation method:

[0057] like Figure 1As shown in (a), the main body of the double-J stent 1 is placed within the ureter 5, with its two ends placed in the renal pelvis 3 and bladder 6, respectively, to achieve urine drainage. Specifically, one end of the double-J stent 1 is placed in the renal pelvis 3, and the curled structure at one end of the double-J stent 1 is placed in the renal pelvis 3 of the kidney 4. The renal pelvis 3 is the structure in the kidney 4 that collects urine. After urine is produced, it first collects in the renal pelvis 3 and then flows through the ureter 5 to the bladder 6. Securing one end of the double-J stent 1 here ensures smooth urine entry into the double-J stent 1. The other end of the double-J stent 1 is fixed to the bladder 6, with the curled structure at the other end of the double-J stent 1 located within the bladder 6. The bladder 6 is an organ that stores urine. After urine is drained from the renal pelvis 3 to the bladder 6 through the double-J stent 1, it can be stored and excreted normally. The present invention uses ultrasound guidance to precisely fit the biodegradable magnesium alloy stent 2 loaded with Rubescensine A 8 to the tumor site. The double J tube 1 is used in combination with the biodegradable magnesium alloy stent 2, which not only retains the above-mentioned drainage function, but also can accurately bring the drug-loaded stent to the site of bladder cancer lesions, thereby achieving the treatment purpose.

[0058] Bladder cancer lesions may be located in the ureter or bladder, or they may be multiple lesions. Intravesical lesions: A biodegradable magnesium alloy stent is placed on the surface of the bladder tumor through the end of a double-J stent, releasing oridonin and magnesium ions to synergistically inhibit the tumor. At the same time, the double-J stent maintains urine drainage, resolving ureteral obstruction caused by tumors in the triangular area. Ureteral opening lesions: The stent is placed in the lower ureter along the double-J stent, supporting the ureter and locally treating the tumor, avoiding damage to the ureter caused by traditional surgery. Multiple lesions: The expandable structure of the biodegradable magnesium alloy 3D stent can cover multiple lesions in the bladder, reducing the complexity of multi-point implantation and improving treatment efficiency.

[0059] like Figure 1 As shown in (b)-(d), the degradable magnesium alloy 3D stent of the present invention is a stent with a three-dimensional structure. Its design simulates the natural three-dimensional microenvironment of human tissue and has important applications in many fields such as medicine and engineering. The degradable magnesium alloy 3D stent adopts a surface calcium-phosphorus coating modification technology (see Example 1 of Publication No. CN118531384A) to form a fine needle-shaped micro-nanostructured calcium-phosphorus coating 7 on the surface of the biodegradable magnesium alloy stent 2. The fine needle-shaped structure is composed of uneven nano-sized needle-shaped crystals and forms a nanopore structure between the needle-shaped crystals. The thickness of the calcium-phosphorus coating is 1 to 20 μm. This coating can significantly improve the biocompatibility and bone integration ability of the magnesium alloy, thereby effectively promoting the repair and healing of bone defects. The degradation products of the biodegradable magnesium alloy stent synergistically exert anti-tumor effects with oridonin 8, such as Mg 2+ , H2 and OH- and other degradation products inhibit tumor cell proliferation, promote apoptosis and alkalize the tumor microenvironment, and enhance the therapeutic effect together with oridonin.

[0060] like Figure 2-Figure 3As shown, the coating effectively improves material corrosion and drug release kinetics:

[0061] The degradation behavior of pure magnesium and magnesium alloys modified with a calcium-phosphorus coating in artificial urine was analyzed. The results showed that during the several-day immersion experiment, the untreated pure magnesium sample exhibited typical rapid corrosion characteristics, with its pH value rising sharply from the initial value to above 10.0 in a short period of time and remaining highly alkaline during the subsequent immersion process. This significant pH increase is due to the vigorous corrosion reaction of the magnesium matrix in the body fluid environment, accompanied by the formation of large amounts of alkaline products such as magnesium hydroxide. In contrast, the magnesium alloy sample modified with a calcium-phosphorus coating exhibited completely different degradation behavior characteristics, with its solution pH value remaining stable within the physiologically friendly range of 8.0 to 9.5 throughout the experimental period. This indicates that the coating effectively regulates the release of alkaline products by inhibiting the rapid degradation of magnesium.

[0062] The experimental results show that the pure magnesium group showed a high viscosity of 22 mm·a in the initial immersion period (0 to 2 days). -1 The corrosion rate was maintained at 10-15 mm·a during the entire experimental period (16 days). -1 In contrast, the corrosion rate of magnesium alloy modified by calcium phosphorus coating always remains at a low level, initially 5 to 8 mm·a -1 , and further decreased to 2-4 mm·a with the extension of immersion time -1 The final corrosion rate was only 1 / 3 to 1 / 5 of that of the pure magnesium group, indicating that the calcium-phosphorus coating significantly improved the corrosion resistance of the magnesium alloy in artificial urine.

[0063] like Figure 4-Figure 5 Scanning electron microscopy (SEM) observations of the surface morphology of the Ca-P-coated magnesium alloy modified with the coating revealed that the Ca-P coating significantly enhanced the corrosion resistance of the magnesium alloy after different immersion times in artificial urine (6 hours, 1 day, 3 days, 7 days, and 14 days). While the uncoated magnesium alloy rapidly degraded with increasing immersion time, the Ca-P-coated group exhibited excellent corrosion stability, maintaining structural integrity, particularly after long-term immersion (14 days). This result demonstrates that the Ca-P coating effectively slowed the degradation rate of the magnesium alloy.

[0064] Experimental results showed that different concentrations of Ori (5μM, 10μM, and 20μM) loaded onto magnesium alloy stents exhibited rapid initial release and sustained release. The rapid release phase lasted from 0 to 12 hours, with all concentration groups experiencing significantly increased release rates within 12 hours, with the 20μM group showing the most rapid release. The sustained release plateau phase lasted from 12 to 36 hours, with drug release reaching a plateau after 36 hours, reaching a cumulative release rate of 80%. The release curves for the different concentration groups showed consistent trends, demonstrating that the coating possesses concentration-independent controlled release capabilities. These results confirm that magnesium alloy stents can achieve efficient loading and controlled release of Rubescensine A, meeting the dual clinical requirements of rapid onset and long-lasting efficacy.

[0065] like Figure 6-Figure 7 As shown, the drug and degradation products synergistically fight tumors, Ori+Mg 2+ The combined action of +Mg(OH)2+H2 exerts a synergistic anti-cancer effect.

[0066] Magnesium alloy combined with Ori has cytotoxicity to bladder cancer cell T24. The magnesium (Mg) CCK-8 method was used to detect the growth inhibitory effect of Ori on bladder cancer cell T24 cells. The results are as follows Figure 6 As shown in the results, magnesium alloy combined with Ori has a cytotoxic effect on bladder cancer cells, and the inhibitory effect gradually increases with the increase of action time.

[0067] like Figure 7 As shown, magnesium alloy and Ori intervened in T24 cells for 24 hours, and the EdU cell proliferation detection experiment showed that compared with the control group, the EdU positive rate of T24 cells in the magnesium alloy and Ori treatment group was significantly reduced, the DNA replication activity was effectively reduced, and the proliferation of bladder cancer cells was significantly inhibited.

[0068] Annexin V-FITC / PI double staining was used to detect the effect of Ori on the apoptosis rate of bladder cancer cells. Figure 8 As shown in the figure, after 24 hours of treatment with different methods for bladder cancer cells, the apoptosis rate (early and late) in the Ori combined with magnesium alloy treatment group was significantly increased compared with the control group, indicating that the combination of Ori and magnesium alloy can increase the apoptosis rate of bladder cancer cells and induce cell apoptosis.

[0069] This invention has significant scientific and advanced significance in the field of bladder cancer treatment. It is the first innovative bladder cancer stent that combines the controlled release of magnesium alloy degradation with synergistic anti-tumor drugs. The world's first integrated design of "double J tube + drug stent" not only gives the double J tube excellent mechanical support and drainage function, but also uses the Mg generated during the degradation process of magnesium alloy to 2+ , H2 and OH- and other multiple mechanisms work synergistically to achieve a highly efficient tumor-suppressing effect.

[0070] Experimental methods:

[0071] 1. pH changes in simulated artificial urine during magnesium alloy degradation in vitro

[0072] Pure magnesium (Pure Mg) and calcium-phosphorus coating modified magnesium alloy (Mg Ca-P) samples were immersed in an artificial urine environment at a constant temperature of 37°C, and the pH value of the solution was monitored regularly using a pH meter. The test period lasted for 14 days, with samples taken at fixed time points every day for testing. Three parallel samples were set up in each group to ensure data reliability. During the experiment, the solution volume was kept constant (50 mL) and placed in a CO2 incubator with a volume concentration of 5% to simulate the in vivo environment to detect the effect of the coating on the degradation behavior of the magnesium alloy.

[0073] 2. Corrosion rate test of calcium-phosphorus coating modified magnesium alloy in artificial urine

[0074] Pure magnesium (pure Mg) and calcium-phosphorus coating modified magnesium alloy (Mg Ca-P) standard specimens (10 mm × 10 mm × 2 mm) were immersed in artificial urine (formulated in accordance with ISO 10993-15) at a constant temperature of 37°C for 16 days. The corrosion rate was determined by weight loss method. The specimens were removed every 2 days, ultrasonically cleaned to remove corrosion products, and then accurately weighed. The corrosion rate (mm·a) was calculated according to ASTM G31-72. -1 The entire experiment was conducted in a constant temperature incubator with a CO2 concentration of 5% to simulate the in vivo environment. Six parallel samples were set up in each group to ensure statistical significance of the data.

[0075] 3. Scanning Electron Microscopy (SEM)

[0076] Coating samples were immersed in 37°C artificial urine for 6 hours, 1 day, 3 days, 7 days, and 14 days, then removed. After rinsing with ultrapure water and vacuum drying, the surface morphology was observed using a field-emission scanning electron microscope (FE-SEM; accelerating voltage 15 kV, working distance 10 mm). Three sets of parallel samples were set up, and elemental composition was determined using energy dispersive spectroscopy (EDS).

[0077] 4. Calcium-phosphorus-coated magnesium alloy stents (5 mm diameter × 10 mm length) loaded with different concentrations of Ori (5 μM, 10 μM, and 20 μM) were placed in PBS buffer (pH 7.4, containing 0.1% Tween 80) at 37°C with constant shaking (100 rpm). High-performance liquid chromatography (HPLC) was used to analyze drug concentrations at predefined time points (0, 2, 4, 6, 8, 12, 24, and 36 h) using a C18 column, a mobile phase of acetonitrile-water (65:35), a flow rate of 1.0 mL / min, and a detection wavelength of 242 nm. Six replicates were used, and data were analyzed using LCsolution software.

[0078] 5. Cell Viability Assay

[0079] The cell density of each group in the logarithmic growth phase was set to 3×10 3 A cell suspension was seeded into a 96-well plate, with 100 μL per well. The cells were cultured in an incubator until they adhered, and the culture medium was discarded. Fresh culture medium containing the specified concentration of drug was added to the experimental group, while the control group received the same volume of fresh culture medium. The cells were treated for the specified time, and then 10 μL of new culture medium (containing 10 μL of CCK8) was replaced. The cells were incubated in a dark incubator for 1 hour, and the absorbance was measured at a wavelength of 450 nm. Three replicates were set for each group. Graphpad Prism software was used to calculate the effects of Ori and magnesium alloy degradation products on bladder cancer cell viability. The bladder cancer cell growth inhibition rate was calculated as follows: Cell growth inhibition rate (%) = (OD control group - OD experimental group) / (OD control group - OD blank control) × 100%.

[0080] 6. EdU cell proliferation assay

[0081] Press 2×10 4 Cells were evenly seeded at a density of 100 μL / well in a 6-well plate equipped with a built-in cell slide. After cells adhered, fresh culture medium containing the designated concentration of drug was added to the experimental group, while the control group received the same volume of fresh culture medium containing the same solvent. The cells were incubated for 12 hours, the culture medium was discarded, and 300 μL of complete culture medium was added. EdU-labeled cells were incubated at 37°C for 2 hours. After EdU labeling, the culture medium was discarded and the cells were washed twice with sterile PBS. Fixative solution was added to the cells with 4% paraformaldehyde, incubated at room temperature for 15 minutes, and the fixative was removed. Wash cells three times with 200 μL of wash solution (2 g / L glycine solution), the wash solution was removed, and the cells were washed once with sterile PBS. 300 μL of permeabilization solution (0.5% Triton X-100) was added to each well, incubated at room temperature for 15 minutes, the permeabilization solution was removed, and the cells were washed once with sterile PBS. The PBS in the cells was discarded, and 100 μL of Click reaction solution was added to each well. The cells were incubated at room temperature for 30 minutes in the dark. Add 1× Hoechst 33342 working solution and incubate at room temperature in the dark for 20 min. Wash three times with PBS, 5 min each time.

[0082] Image acquisition and analysis:

[0083] (1) Observe and photograph under a fluorescence microscope using DAPI and CY3 fluorescence modules in the dark.

[0084] (2) Count the number of EdU-positive cells using Image J software and calculate the EdU staining positivity rate. The EdU staining positivity rate was calculated as follows:

[0085] EdU staining positive rate (%) = number of EdU positive cells / total number of DAPI stained cells × 100%

[0086] 7. Cell Cycle Detection

[0087] The cells were plated at 5×10 4 Cells were seeded at a density of 100 cells / well in a 6-well plate. Once cells adhered and reached approximately 60-70% confluency, the culture medium was discarded. Fresh culture medium containing different concentrations of drug was added to the experimental group, while the same volume of fresh culture medium with solvent was added to the control group. Culture was continued for another 24 hours. The original culture medium was discarded, and the cells were washed twice with sterile PBS. Trypsin was added to disintegrate the cells. After digestion, the adherent cells were gently aspirated with a pipette and collected into a centrifuge tube. Centrifuged at 800 rpm at 4°C for 5 minutes in a clean hood. The supernatant was discarded. 1 mL of pre-chilled sterile PBS was added to resuspend the cells and transfer them to a 1.5 mL EP tube. Centrifuged again, and the supernatant was carefully aspirated. Gently tap the bottom of the EP tube to prevent cell clumping. 1 mL of 70% ethanol was added and gently pipetted to mix well. The tube was fixed overnight at 4°C for at least 24 hours. The next day, the tube was centrifuged at 1000 rpm at 4°C for 5 minutes. The supernatant was carefully removed. The cells were resuspended in 1 mL of pre-chilled sterile PBS, allowed to stand for 15 minutes, and pelleted by centrifugation again. The supernatant was discarded. Prepare propidium iodide working solution (3 mL of staining buffer, 150 μL of propidium iodide staining solution (20×), and 60 μL of RNase A) and store at 4°C in the dark. Add 500 μL of propidium iodide working solution to each EP tube and incubate for 30 minutes in the dark. Perform analysis using flow cytometry, ensuring that cells are thoroughly mixed before loading. Analyze cell cycle distribution using FlowJo software.

[0088] like Figure 1 、 Figure 9 As shown, the present invention provides an innovative interventional treatment solution for bladder cancer, which achieves precise treatment by combining a double-J tube 1 with a drug-loaded biodegradable magnesium alloy stent 2. In specific implementation, ultrasound imaging is first used to accurately locate the tumor lesion and determine the specifications of the stent. Then, under real-time ultrasound guidance, a pre-connected stent-double-J tube system is implanted through the urethra to ensure that the stent completely covers the tumor area. The surface of the stent is modified with a calcium-phosphorus coating and has a dual regulatory function: on the one hand, it controls the degradation of the magnesium alloy at an optimized rate of 2 to 4 mm / a and maintains a physiological pH range of 8.0 to 9.5; on the other hand, it realizes the sustained release of anticancer drugs, forming a direct killing effect of the drug and a degradation product of metal magnesium (Mg 2+, H2, and Mg(OH)2) microenvironment regulation for synergistic therapeutic effects. This system is particularly suitable for frail elderly patients, those undergoing advanced palliative care, those at high risk of postoperative recurrence, and those with ureteral obstruction. A single minimally invasive implant replaces 18 traditional intravesical chemotherapy sessions, avoiding the damage caused by repeated catheterization and addressing drug penetration barriers caused by bladder anatomy. After the treatment cycle, the stent can be removed with the double-J stent or completely degraded and absorbed, significantly improving treatment precision, safety, and patient compliance.

[0089] The implementation results show that the technical advantages of the present invention are reflected in the following six aspects:

[0090] 1. Precision Therapy: This implantable drug delivery system can be placed directly in the surgical cavity after surgery, delivering the therapeutic agent directly to the surgical incision. This allows for long-term local release of the drug, thereby inhibiting tumor recurrence. Furthermore, localized release effectively prevents drug circulation through the bloodstream, increasing drug concentration at the target site, thereby effectively reducing tumor resistance and minimizing toxic reactions in other organs.

[0091] 2. Fine Needle-Like Micro-Nanostructured Calcium-Phosphate Coating: A fine needle-like micro-nanostructured calcium-phosphate coating is formed on the surface of a magnesium alloy substrate. This coating is composed of unevenly sized, nanometer-sized needle-like crystals, with a nanopore structure formed between the needle-like crystals. This high surface area and unique pore structure help increase drug loading, enhance drug-coating interactions, improve drug stability, and promote drug dissolution and diffusion, helping to improve drug release kinetics. This coating is suitable for drugs requiring rapid or targeted release. Furthermore, this structure effectively mitigates the degradation rate, corrosion resistance, and mechanical properties of magnesium metal, extending the lifespan of the implant in the body.

[0092] 3. Improve Ori utilization: Magnesium-based metal implants, as drug carriers, can act directly on tumor tissue through local delivery, thereby reducing the systemic side effects of drugs. The increase in local drug concentration helps to enhance the effect of the drug and thus improve the bioavailability of the drug.

[0093] 4. Improve patient treatment compliance: This implantable drug delivery system only needs to be implanted once to continuously release drugs, reducing the patient's treatment burden and improving their treatment compliance and quality of life.

[0094] 5. Synergistic anti-tumor effect: The degradation products of magnesium alloy have significant anti-tumor effects. H2 and Mg 2+ It can not only inhibit the proliferation of tumor cells, but also promote apoptosis. -Maintaining a continuous alkalinization of the tumor microenvironment, thereby exerting an anti-tumor effect; at the same time, Ori has confirmed its anti-tumor effect in a bladder cancer model. Therefore, this drug delivery system has a significant synergistic effect in anti-tumor treatment and is expected to provide cancer patients with a new type of treatment with high efficiency and low toxicity.

[0095] 6. Wide Range of Applications: This product is suitable for patients with urothelial carcinoma who are choosing palliative treatment, as well as those who require a double-J stent after transurethral bladder tumor resection. This drug delivery system is a treatment method that can deliver drugs directly to the cancer site. This method can achieve precise drug delivery to the tumor site while minimizing damage to normal tissue. It slowly releases chemotherapy drugs in the body, prolonging the drug's duration of action. It also works with the magnesium-based alloy drug carrier to effectively eliminate residual tumor cells, reducing the risk of recurrence and metastasis, thereby improving the precision and effectiveness of treatment and providing a more effective and safe treatment option for bladder cancer patients.

Claims

1. A drug delivery system based on a biodegradable magnesium alloy stent combined with a double J tube, characterized in that: The system includes a biodegradable magnesium alloy stent and a double J tube. The surface of the biodegradable magnesium alloy stent is modified with a calcium-phosphorus coating to form a fine needle-like micro-nanostructure. The biodegradable magnesium alloy stent is loaded with the anticancer drug oridonin.

2. The drug delivery system based on the biodegradable magnesium alloy stent combined with the double J tube according to claim 1, characterized in that: The main part of the double-J tube is placed in the ureter, one end of the double-J tube is inserted into the renal pelvis, and the curled structure at one end of the double-J tube is placed in the renal pelvis of the kidney. The other end of the double-J tube is fixed to the bladder, and the curled structure at the other end of the double-J tube is located in the bladder. After the urine is drained from the renal pelvis to the bladder through the double-J tube, it is stored and excreted normally from the body. With the help of ultrasound guidance, the biodegradable magnesium alloy stent loaded with oridonin is precisely fitted to the tumor site, realizing the combination of the double-J tube and the biodegradable magnesium alloy stent.

3. The drug delivery system based on the biodegradable magnesium alloy stent combined with the double J tube according to claim 2, characterized in that: For lesions within the bladder, a biodegradable magnesium alloy stent is placed on the surface of the bladder tumor through the end of the double-J tube, releasing oridonin and magnesium ions to synergistically inhibit the tumor; for lesions at the ureteral opening, a biodegradable magnesium alloy stent is placed in the lower part of the ureter along the double-J tube, which not only supports the ureter but also locally treats the tumor.

4. The drug delivery system based on the biodegradable magnesium alloy stent combined with the double J tube according to claim 1, characterized in that: The biodegradable magnesium alloy stent is a 3D stent. Surface calcium-phosphorus coating modification technology is used to form a fine needle-like micro-nanostructured calcium-phosphorus coating on the surface of the biodegradable magnesium alloy stent. The fine needle-like structure is composed of uneven nano-sized needle-like crystals, and a nanopore structure is formed between the needle-like crystals.

5. The drug delivery system based on the biodegradable magnesium alloy stent combined with the double J tube according to claim 4, characterized in that: The diameter of the fine needle-like structure ranges from 150 to 650 nm, the length ranges from 2 to 15 μm, and the thickness of the calcium-phosphorus coating ranges from 1 to 20 μm.

6. The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube according to claim 4, characterized in that: The fine needle-shaped micro-nanostructured calcium phosphate coating is composed of needle-shaped crystals of uneven nanometer size, and a nanopore structure is formed between the needle-shaped crystals. Oridonin is loaded in the nanopores of the calcium phosphate coating, and the drug loading concentration is 5 to 20 μM.

7. The drug delivery system based on the biodegradable magnesium alloy stent combined with a double J tube according to claim 1, characterized in that: Calcium-phosphorus coating can significantly improve the corrosion resistance of magnesium alloys and achieve precise control of the degradation rate of magnesium metal, making the corrosion rate of magnesium alloys 2-4 mm·a -1 .

8. The drug delivery system based on the biodegradable magnesium alloy stent combined with a double J tube according to claim 1, characterized in that: The biodegradable magnesium alloy stent is integrated with the double-J tube and then directly implanted into the tumor lesion to achieve efficient and precise drug delivery.

9. The drug delivery system based on the combination of a biodegradable magnesium alloy stent and a double-J tube according to claim 1, characterized in that: The degradation products of biodegradable magnesium alloy stents include magnesium ions, hydrogen gas and magnesium hydroxide, which synergistically exert anti-tumor effects with the anticancer drug oridonin.

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