Hydrogel for submucosal lifting and hemostatic sealing

Abstract

In some embodiments, the present disclosure relates to injectable polysaccharide-based hydrogels comprising an anionic polysaccharide, a cationic crosslinker and a hemostatic agent. In some embodiments, the present disclosure relates to medical devices containing such injectable polysaccharide-based hydrogels, kits containing such injectable polysaccharide-based hydrogels, and methods of using such injectable polysaccharide-based hydrogels.

Description

[Technical field]

[0001] The present disclosure relates to injectable gels that are useful in a variety of medical procedures, including use as lifting agents for endoscopic mucosal resection and abrasion procedures. [Background technology]

[0002] Injectable compositions are commonly used to separate one structure from another, to separate, elevate, and / or stabilize the first structure in order to perform a medical diagnostic or therapeutic step safely, quickly, and efficiently. For example, endoscopic procedures such as endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), colonic polypectomy, and perioral endoscopic myotomy (POEM) are commonly performed to detect and remove malignant and premalignant lesions, tumors, and / or other unhealthy tissue within the mucosal and submucosal layers of the gastrointestinal (GI) tract. To reduce the risk of perforating the GI tract, medical practitioners generally separate the submucosa from the underlying muscularis layer before performing a resection or ablation procedure. A typical method of establishing this separation is to inject a fluid between the muscularis layer and the submucosal layer.

[0003] Surgical removal of tissue results in internal wounds and exposure to bleeding. A common step in the procedure is obtaining adequate mucosal closure. Several techniques are available for mucosal closure, including the use of endoscopic clips and / or endoscopic sutures. Summary of the Invention [Means for solving the problem]

[0004] The present disclosure relates to injectable hydrogel compositions useful in a variety of medical procedures that are adapted to provide both submucosal lifting and hemostatic sealing treatment to tissue areas immediately following resection or dissection.

[0005] In some aspects, the present disclosure relates to an injectable polysaccharide-based hydrogel comprising an anionic polysaccharide, a cationic crosslinker, and a hemostatic agent. In some embodiments, the anionic polysaccharide contains repeating units of glucuronic acid. In a particular example, the anionic polysaccharide comprises gellan gum.

[0006] In some embodiments that can be used in conjunction with the above aspects and embodiments, the anionic polysaccharide is provided at a concentration ranging from about 0.010% to about 2.5% by weight of the total injectable polysaccharide-based hydrogel.

[0007] In some embodiments that can be used in conjunction with the above aspects and embodiments, the cationic crosslinker comprises a salt comprising a divalent metal cation, and / or the crosslinker comprises a branched polyamine comprising two or more primary amine groups that are positively charged at the pH of the hydrogel.

[0008] In some embodiments that can be used in conjunction with the above aspects and embodiments, the cationic crosslinker is provided at a concentration ranging from about 0.005% to about 2.5% by weight of the total injectable polysaccharide-based hydrogel.

[0009] In some embodiments that can be used in conjunction with the above aspects and embodiments, the hemostatic agent is selected from organic polymeric hemostatic agents, small molecule organic hemostatic agents, large molecule organic hemostatic agents, and inorganic hemostatic agents. In certain embodiments, the hemostatic agent may be selected from chitosan, hydroxyapatite, or tranexamic acid.

[0010] In some embodiments that can be used in conjunction with the above aspects and embodiments, the hemostatic agent is in particulate form and has an average particle size of less than 50,000 nm. In some embodiments that can be used in conjunction with the above aspects and embodiments, the hemostatic agent is provided at a concentration ranging from about 5% to about 50% by weight of the total injectable polysaccharide-based hydrogel.

[0011] In some embodiments, which can be used in conjunction with the above aspects and embodiments, the injectable polysaccharide-based hydrogel further comprises a colorant. In some aspects, the present disclosure relates to a medical device comprising a reservoir containing an injectable polysaccharide-based hydrogel according to any of the aforementioned aspects and embodiments.

[0012] In some embodiments, the reservoir is a syringe barrel. In some embodiments, the medical device comprises a needle through which the injectable polysaccharide-based hydrogel is injected.

[0013] In some aspects, the present disclosure relates to the use of a medical device according to any of the above aspects and embodiments in a medical procedure in which an upper mucosal layer is lifted from an underlying layer. In some aspects, the present disclosure relates to a method of separating and elevating an upper mucosal layer from a lower layer, comprising injecting an injectable polysaccharide-based hydrogel according to any of the aforementioned aspects and embodiments through a needle into a target treatment site between the upper mucosal layer and the lower layer.

[0014] In some embodiments, the method further comprises removing tissue lifted by the injectable polysaccharide-based hydrogel. In some embodiments, the method is performed as part of an endoscopic mucosal resection or endoscopic submucosal dissection.

[0015] In some embodiments, the method is performed using a medical device further comprising a flexible tube connecting a syringe barrel to a needle, and the injectable polysaccharide-based hydrogel is injected from the syringe barrel, through the flexible tube, through the needle and into the target site.

[0016] In some aspects, the present disclosure relates to a kit comprising a medical device according to any of the foregoing aspects and embodiments, and one or more items selected from (a) an endoscopic injection needle, (b) a tissue resection device, (c) a tissue retrieval device, and (d) an endoscope, within suitable packaging material. [Brief description of the drawings]

[0017] [Figure 1A] 1 illustrates an exemplary medical device according to certain aspects of the present disclosure. [Figure 1B] 1 illustrates an exemplary medical device according to certain aspects of the present disclosure. [Figure 1C] 1 illustrates an exemplary medical device according to certain aspects of the present disclosure. [Figure 2A] 1 illustrates an exemplary tissue ablation procedure, according to certain aspects of the present disclosure. [Figure 2B] 1 illustrates an exemplary tissue ablation procedure in accordance with certain aspects of the present disclosure. [Figure 2C] 1 illustrates an exemplary tissue ablation procedure in accordance with certain aspects of the present disclosure. [Figure 2D] 1 illustrates an exemplary tissue ablation procedure, according to certain aspects of the present disclosure. [Figure 2E] 1 illustrates an exemplary tissue ablation procedure in accordance with certain aspects of the present disclosure. [Diagram 3] 1 shows the recovery of 6-aminocaproic acid in D-PBS supernatant as a function of time, according to an embodiment of the present disclosure. [Figure 4] 1 shows the recovery of tranexamic acid in D-PBS supernatant as a function of time, according to an embodiment of the present disclosure. [Diagram 5] 1 is a photomicrograph of a particulate hemostat having a core comprising a chitosan salt and a shell comprising a tripolyphosphate salt. [Figure 6] 1 is a graph of particle size distribution, volume density (%) versus particle size (μm) for a population of hemostat particles having a core comprising a chitosan salt and a shell comprising a tripolyphosphate salt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present disclosure relates to polysaccharide-based hydrogels that contain hemostatic agents at the point of administration. The hydrogels allow tissue to be lifted, facilitating surgical removal. The hydrogels also have hemostatic properties that reduce or prevent bleeding at the surgical site. In this way, the need for interventions using clips or sutures may be eliminated. Additionally, the hydrogels may reduce the incidence of intraoperative bleeding from surrounding tissues that may occur during clipping or suture removal after the procedure.

[0019] According to various aspects of the present disclosure, the polysaccharide-based hydrogel can include a polysaccharide, a crosslinking agent, and a hemostatic agent at the site of administration. In some embodiments, the polysaccharide, crosslinking agent, and hemostatic agent are provided in a single injectable composition. In some embodiments, the polysaccharide is crosslinked to form a hydrogel in a reservoir from which it is injected into a patient as a hydrogel.

[0020] In some embodiments, a first injectable composition comprising a polysaccharide and a cross-linking agent is administered simultaneously with a second injectable composition comprising a hemostatic agent. Several options are available for administering the polysaccharide, crosslinker, and hemostatic agent to a target site in a patient, including, among others: (a) particles of the hemostatic agent can be suspended in a hydrogel comprising the polysaccharide and the crosslinker; (b) the hemostatic agent can be dissolved in a hydrogel comprising the polysaccharide and the crosslinker; (c) an injectable composition comprising a hemostatic agent in which particles of the hemostatic agent are suspended in a liquid or hydrogel can be administered simultaneously with an injectable hydrogel composition comprising the polysaccharide and the crosslinker; (d) an injectable composition comprising a hemostatic agent dissolved in a liquid or hydrogel can be administered simultaneously with an injectable hydrogel composition comprising the polysaccharide and the crosslinker; or (e) the hemostatic agent can be in a dry state (e.g., as pure particles, coated particles, etc.) and premixed with a hydrogel composition comprising the polysaccharide and the crosslinker prior to administration.

[0021] Suitable polysaccharides for use in forming the injectable compositions of the present disclosure include natural polysaccharides (e.g., natural gums such as vegetable gums and / or microbial gums) and synthetic polysaccharides. The polysaccharides in the compositions of the present disclosure are typically anionic polysaccharides. Non-limiting examples of polysaccharides include anionic polysaccharides containing repeating units of glucuronic acid, such as gellan gum, alginates, and xanthan gum, among others.

[0022] In various embodiments, gellan gum may be preferred. As used herein, "gellan gum" refers to a polysaccharide (e.g., produced by Sphingomonas bacteria) with a general structure formed from repeating units of four sugars linked together: two residues of D-glucose, one residue of L-rhamnose, and one residue of D-glucuronic acid. The polysaccharide may include one or more types of gellan gum, e.g., native gellan gum, deacylated gellan gum, or a mixture thereof. Native gellan gum may include two acyl groups (e.g., acetate and glycerate) attached to a glucose residue adjacent to a glucuronic acid residue. These acyl groups can be removed under alkaline conditions to produce deacylated gellan gum, which results in different stability and plasticity properties compared to native gellan gum. For example, native gellan gum generally forms softer, more elastic gels with thermoreversibility, while deacylated gellan gum generally forms harder, less elastic gels with higher heat resistance. In at least one embodiment, the injectable composition comprises deacylated gellan gum. Further information regarding polysaccharide hydrogels can be found, for example, in U.S. Patent Application Publication Nos. 2019 / 0247301, 2018 / 0021252, and 2017 / 0281862, the disclosures of which are incorporated herein by reference.

[0023] Certain microbial extracts may contain endotoxins, such as bacterially derived lipopolysaccharides, which are comprised of a combination with polysaccharide structures. In some embodiments, the polysaccharide(s) may be selected to minimize or eliminate the introduction of endotoxins into the composition. In some instances, the polysaccharide(s) may have an endotoxin level of 20 Endotoxin Units (EU) or less. Bacterial endotoxin levels may be measured, for example, using the Limulus Amebocyte Lysate (LAL) test. Alternatively or additionally, the polysaccharide(s) may be treated to reduce or eliminate the concentration of endotoxins prior to use in the compositions disclosed herein. For example, the compositions may contain microbially derived polysaccharides that have been treated to reduce the amount of endotoxins present, such that the resulting compositions are pharmaceutically acceptable and comply with applicable government regulatory standards.

[0024] In some embodiments, the polysaccharide is provided at a concentration ranging from about 0.01% or less to about 2.5% or more by weight of the total polysaccharide-based hydrogel at the site of administration. For example, the polysaccharide may be provided at a concentration ranging from about 0.010%, to about 0.025%, to about 0.05%, to about 0.10%, to about 0.25%, to about 0.5%, to about 0.75%, to about 1.0%, to about 1.25%, to about 1.5%, to about 1.75%, to about 2.0%, to about 2.25%, to about 2.5% by weight of the total polysaccharide-based hydrogel at the site of administration (in other words, a range between any two or more of the above values).

[0025] Suitable crosslinking agents for use in forming the polysaccharide-based hydrogels of the present disclosure include covalent crosslinking agents and / or ionic crosslinking agents. The crosslinking agents in the injectable compositions of the present disclosure more typically include polyvalent cationic crosslinking agents. In particularly beneficial embodiments, the injectable compositions may include a salt containing a divalent cation. Non-limiting examples of such salts include salts containing divalent metal cations, such as calcium and / or magnesium cations, such as calcium chloride (CaCl2), magnesium sulfate (MgSO4), magnesium chloride (MgCl2), any hydrates thereof, and any mixtures thereof. In one particular example, the salt(s) having a divalent cation include calcium chloride or a hydrate thereof, such as calcium chloride dihydrate. In some embodiments, the crosslinking agent may include a branched polyamine containing two or more primary amine groups that are positively charged at the pH of the hydrogel, and the branched polyamine ionically crosslinks the polysaccharide. Non-limiting examples of such branched polyamines include trilysine, tetralysine, pentalysine, tris(aminoalkyl)amines (e.g., tris(2-aminoethyl)amine, tris(aminoalkyl)alkanes (e.g., 1,1,1-tris(aminomethyl)ethane)), and any mixtures thereof.

[0026] In some cases, the polysaccharide-based hydrogel may include at least one salt containing a monovalent cation and at least one salt containing a divalent cation. For example, the injectable composition may include at least one sodium or potassium salt and at least one calcium or magnesium salt, such as, for example, NaCl and CaCl2, or NaCl and MgCl2, or KCl and CaCl2, or KCl and MgCl2, etc. Furthermore, for example, the injectable composition may include at least one monovalent salt selected from sodium chloride, potassium chloride, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium gluconate, or sodium acetate trihydrate in combination with at least one salt selected from calcium chloride, magnesium sulfate, or magnesium chloride.

[0027] In some embodiments, the salt with a divalent cation is provided at a concentration ranging from about 0.005% or less to about 0.200% or more by weight of the total polysaccharide-based hydrogel at the administration site. For example, the salt with a divalent cation can be provided at any concentration ranging from about 0.005% to about 0.010%, to about 0.015%, to about 0.020%, to about 0.025%, to about 0.030%, to about 0.040%, to about 0.050%, to about 0.075%, to about 0.100%, to about 0.150%, to about 0.200% by weight of the total polysaccharide-based hydrogel at the administration site.

[0028] In some embodiments, the salt with a monovalent cation is provided at a concentration ranging from about 0.1% or less to about 5.0% or more by weight of the total polysaccharide-based hydrogel at the site of administration. For example, the salt with a monovalent cation can be provided at any concentration ranging from about 0.10%, to about 0.25%, to about 0.50%, to about 0.75%, to about 1.0%, to about 1.5%, to about 2.0%, to about 5.0% by weight of the total polysaccharide-based hydrogel at the site of administration.

[0029] Further, for example, the composition may include a salt solution having an osmolarity ranging from about 240 mOsmol / kg to about 340 mOsmol / kg (e.g., 290 mOsmol / kg±50 mOsmol / kg), e.g., from about 250 mOsmol / kg to about 320 mOsmol / kg, or from about 280 mOsmol / kg to about 300 mOsmol / kg. The solution may be physiologically compatible, e.g., having electrolyte levels, osmolarity, and pH suitable for infusion into a patient. The pH of the solution may be adjusted using a suitable base, such as sodium hydroxide, to increase the pH, and / or a suitable acid, such as hydrochloric acid, or by other means or with other substances that provide a biocompatible composition.

[0030] As noted above, in addition to the polysaccharide and crosslinking agent, the polysaccharide-based hydrogels of the present disclosure include a hemostatic agent at the site of administration. Any suitable hemostatic agent may be used in the present disclosure. Hemostatic agents for use in the present disclosure include organic polymeric hemostatic agents, small molecule hemostatic agents, inorganic hemostatic agents, or large molecule hemostatic agents.

[0031] Organic polymeric hemostatic agents include those containing chitosan, chitosan derivatives, dextran and dextran derivatives. Chitosan is a modified polysaccharide containing randomly distributed β-(1→4)-linked D-glucosamine (the deacetylated unit) and N-acetyl-D-glucosamine (the acetylated unit). Chitosan is commercially produced by alkaline N-deacetylation of modified glucose, specifically chitin, a cellulose-like polymer composed primarily of unbranched chains of N-acetyl-D-glucosamine. The degree of deacetylation of commercially available chitosan generally ranges from 60%, 70%, 80%, 90% to 100%, although essentially any degree of deacetylation is possible. Commercially available chitosan is available in a range of molecular weights, including low molecular weight chitosan (e.g., having a molecular weight in the range of 10 kDa to 190 kDa), medium molecular weight chitosan (e.g., having a molecular weight in the range of 190 kDa to 310 kDa), high molecular weight chitosan (e.g., having a molecular weight in the range of 310 kDa to 375 kDa), and ultra-high molecular weight chitosan (e.g., having a molecular weight greater than 375 kDa).

[0032] Chitosan is also positively charged in acidic to neutral solutions, with the charge density depending on the pH and the degree of deacetylation. The pka value of chitosan generally ranges from 6.1 to 7.0, depending on the degree of deacetylation. Thus, chitosan is practically insoluble in distilled water, but generally soluble in dilute aqueous acid solutions (e.g., pH=6.5 or less).

[0033] In some embodiments, chitosan is in an organic salt form, including organic acid salts of chitosan based on acetic acid (acetate) or citric acid (citrate). In some embodiments, the organic polymeric hemostatic agent comprises a soluble form of chitosan.

[0034] In some embodiments, the organic polymeric hemostatic agent comprises chitosan in particulate form. In some embodiments, the organic polymeric hemostatic agent in particulate form is lyophilized.

[0035] In some embodiments, the particulate hemostatic agent comprises a core comprising a chitosan salt and a shell comprising a polyphosphate crosslinker comprising a polyanionic crosslinker, e.g., lithium, sodium or potassium salt of polymetaphosphate, such as tripolyphosphate, trimetaphosphate and hexametaphosphate. Particles with the inverse structure (i.e., having a core comprising tripolyphosphate and a shell comprising chitosan salt) have been made. See Ondrej Kaspar et al., "Characterization of spray dried chitosan TPP microparticles formed by two-and three-fluid nozzles," Powder Technology 240 (2013) 31-40. However, to the best of the inventors' knowledge, core-shell particles with the structure of the present disclosure have not been prepared to date. Furthermore, the particles of Kaspar et al. are directed to microencapsulation applications where chitosan is used as the encapsulant.

[0036] In some embodiments, the organic polymer hemostatic agent is provided at a concentration ranging from about 5% to about 50%, e.g., from 5%, to 10%, to 20%, to 30%, to 40%, to 50%, based on the total weight of the polysaccharide-based hydrogel at the administration site.

[0037] When provided in particulate (insoluble) form, the organic polymeric hemostatic agent may have an average particle size ranging from 10 to 100,000 nm, e.g., from 10 nm to 25 nm, 50 nm, 100 nm, 250 nm, 500 nm, 750 nm, 1000 nm, 2,500 nm, 5,000 nm, 10,000 nm, 25,000 nm, 50,000 nm, 100,000 nm. In certain embodiments, the average particle size is in the range of 10 to 999 nm, e.g., 100 to 300 nm.

[0038] When provided in particulate form, the organic polymeric hemostat particles may include a shell that includes a polyanionic crosslinker, such as a polyanionic phosphate crosslinker. When provided in particulate form, the organic polymeric hemostat particles may further be provided with a coating, such as a heat-sensitive coating or a pH-sensitive coating.

[0039] Inorganic hemostatic agents include calcium phosphate minerals such as hydroxyapatite and Whitlockite. Hydroxyapatite has the formula Ca5(PO4)3(OH), but is usually referred to as Ca 10 Whitlockite is reported to have the formula Ca9(MgFe)(PO4)6PO3OH.

[0040] In some embodiments, the inorganic hemostatic agent is provided at a concentration ranging from about 5% to about 50%, e.g., from 5%, to 10%, to 20%, to 30%, to 40%, to 50%, based on the total weight of the polysaccharide-based hydrogel at the administration site.

[0041] The inorganic hemostatic agent may have an average particle size in the range of 10 nm to 999 nm, for example, from 10 nm to 25 nm, 50 nm, 100 nm, 250 nm, 500 nm, 750 nm, to 999 nm, typically 100 nm to 300 nm. The inorganic hemostatic agent particles may be provided with a coating, such as a heat-sensitive coating or a pH-sensitive coating.

[0042] Small molecule organic hemostatic agents include amino acids such as tranexamic acid, aminocaproic acid, and 4-aminomethylbenzoic acid. In some embodiments, the small molecule organic hemostatic agent is provided at a concentration ranging from about 5% to about 50% by weight of the total polysaccharide-based hydrogel at the site of administration.

[0043] The small molecule organic hemostatic agent can be provided in dissolved form or in particulate form, including soluble and insoluble particulate forms. When provided in particulate form, the small molecule organic hemostatic agent can have an average particle size in the range of 10-999 nm, for example, from 10 nm, to 25 nm, to 50 nm, to 100 nm, to 250 nm, to 500 nm, to 750 nm, to 999 nm, typically 100-300 nm.

[0044] Large molecule organic hemostatic agents include hemostatic proteins such as thrombin, fibrin and fibrinogen. In some embodiments, the large molecule organic hemostatic agent is provided at a concentration ranging from about 5% to about 50%, e.g., from 5%, to 10%, to 20%, to 30%, to 40%, to 50%, based on the total weight of the polysaccharide-based hydrogel at the administration site.

[0045] The large molecule organic hemostatic agent may be provided in a dissolved or particulate form. When provided in particulate form, the large molecule organic hemostatic agent may have an average particle size in the range of 10 to 999 nm, for example, from 10 nm to any of the ranges of 25 nm, 50 nm, 100 nm, 250 nm, 500 nm, 750 nm, and 999 nm, typically 100 to 300 nm.

[0046] The compositions of the present disclosure may contain further additives in addition to the polysaccharides, crosslinking agents and hemostatic agents described above. In some embodiments, the composition may include one or more coloring agents. In some cases, the coloring agent(s) may allow identification of the submucosal tissue plane upon injection into the tissue, for example, to determine the amount of tissue to be removed and / or to assess the risk of perforation. Examples of coloring agents include, but are not limited to, brilliant blue (e.g., brilliant blue FCF, also known as FD&C Blue 1), indigo carmine (also known as FD&C Blue 2), indigo carmine lake, FD&C Blue 1 Lake, methylene blue (also known as methylthioninium chloride), or mixtures thereof, among others.

[0047] In some embodiments, the composition may include other suitable types of biocompatible agents. For example, the composition may include an agent for adjusting the pH and / or tonicity of the composition as needed. For example, the composition may include one or more stabilizers and / or preservatives.

[0048] As previously indicated, according to various aspects of the present disclosure, the compositions of the present disclosure can be used to create a polysaccharide-based hydrogel comprising a polysaccharide, a crosslinker and a hemostatic agent at the site of administration to a patient (e.g., a target site between layers of tissue). When the polysaccharide-based hydrogel is used as a submucosal tissue lifting agent, tissue resection and / or peeling can be performed after hydrogel injection and submucosal tissue lifting. Surgical removal of tissue creates an internal wound and exposes it to bleeding. The hemostatic properties of the polysaccharide-based hydrogel promote hemostasis at the site of administration, for example, as a physical clotting agent, by elution of a hemostatic agent (e.g., elution of a small molecule active pharmaceutical ingredient such as tranexamic acid or aminocaproic acid), or both.

[0049] In some embodiments, the polysaccharide, crosslinker and hemostatic agent are provided in a single injectable composition. In some embodiments, a first injectable co-composition comprising the polysaccharide and the crosslinker is co-administered with a second injectable co-composition comprising the hemostatic agent. Thus, in some embodiments, the crosslinked hydrogel is preloaded with the hemostatic agent and administered to the target site. In some embodiments, the crosslinked hydrogel is co-administered with the hemostatic agent.

[0050] As previously indicated, the hemostatic agent may be in solid form (e.g., as particles) or in solution form when administered. After administration, the hemostatic agent may change form under physiological conditions. For example, particles of the hemostatic agent may dissolve under physiological conditions, or solutions of the hemostatic agent may precipitate under physiological conditions.

[0051] The hemostatic agent may provide immediate and / or long-term treatment at the site of tissue occlusion. For example, the hemostatic agent may remain in place after surgery and complex with a hydrogel or act as a hemostatic depot to allow elution of the hemostatic agent for a period of time after surgery, thereby providing an extended therapeutic profile. Typically, a portion of the crosslinked hydrogel is removed with the tissue, but the remaining crosslinked hydrogel slowly biodegrades over time and may remain in place through and beyond the healing phase.

[0052] As mentioned above, the present disclosure provides compositions and co-compositions for injection into a patient. In use, the composition to be administered or the co-composition to be administered (e.g., a hydrogel, solution, etc.) can be delivered to the target site in the patient via an appropriate medical device (e.g., a syringe or fluid reservoir connected to an injection needle).

[0053] The composition and co-composition may have a suitable viscosity for injection from a selected medical device. In some embodiments, the composition or co-composition may be pseudoplastic. Pseudoplastic generally refers to the property of viscosity decreasing when shear force is applied. Thus, for example, the composition may have a higher viscosity at rest or under low shear conditions (e.g., while stored in a container) than during high shear conditions (e.g., during filling and / or injection through a needle).

[0054] The composition and co-composition can be sterilized by various methods. For example, the composition and co-composition can be autoclaved while in a reservoir such as a syringe barrel by heating the mixture at or to a temperature of about 121° C. Alternatively or additionally, the composition and co-composition can be sterilized via sterile filtration and / or by introducing gamma or electron beam radiation into the reservoir.

[0055] The present disclosure also provides medical devices comprising the compositions and co-compositions described herein. The medical devices can be used to inject the compositions or co-compositions into tissue of a patient, for example, to ablate at least a portion of the tissue.

[0056] According to some aspects of the present disclosure, the medical device may include one or more reservoirs. The reservoir(s) may function as a container(s) for the compositions and co-compositions described herein. Suitable reservoirs may include, for example, syringe barrels (e.g., syringe barrels compatible with manual or automatic injection systems), flexible pouches such as plastic bags, and other fluid containers configured for use with a suitable injection needle. Exemplary materials suitable for the reservoir include, but are not limited to, cyclic olefin copolymers, cyclic olefin polymers, polypropylene, polycarbonate, polyvinyl chloride, and glass.

[0057] The medical devices described herein may include one or more needles. In some embodiments, the reservoir of the medical device may be directly coupled to the needle, for example, via a luer adapter or other suitable connection, or may be indirectly coupled to the needle via a flexible tube, such as a catheter. Non-limiting examples of needles that are coupled to a reservoir via a flexible tube include Interject™ sclerotherapy needles by Boston Scientific. In some examples, the needle(s) may be hypodermic injection needles and may range in size from 7 gauge (4.57 mm outer diameter (OD), 3.81 mm inner diameter (ID)) to 33 gauge (0.18 mm OD, 0.08 mm ID), for example, 16 gauge (1.65 mm OD, 1.19 mm ID), to 21 gauge (0.82 mm OD, 0.51 mm ID), to 22 gauge (0.72 mm OD, 0.41 mm ID), to 23 gauge (0.64 mm OD, 0.33 ID), to 24 gauge (0.57 mm OD, 0.31 mm ID), among other sizes. Exemplary materials for the needle(s) include, but are not limited to, metals and metal alloys, such as stainless steel and nitinol, and polymers. The distal tip of the needle may be sharpened and may have a beveled shape. The proximal end of the needle may include a suitable fitting / adapter (e.g., a Luer adapter) for engagement with a syringe barrel or other reservoir. In some embodiments, the needle may include an elongated tube or catheter between the needle tip and the proximal fitting / adapter.

[0058] Further disclosed herein is a method of excising at least a portion of a tissue from a subject (e.g., a human patient). The method can include injecting a composition described herein into the tissue of the subject and excising at least a portion of the tissue from the patient.

[0059] FIG. 1A shows an exemplary syringe 10 that provides a reservoir for a composition or co-composition 15 as described above. The syringe 10 may include a barrel 12, a plunger 14, and one or more stoppers 16. The barrel 12 may include a luer adapter (or other suitable adapter / connector), for example at a distal end 18 of the barrel 12, for attachment to an injection needle 50 via a flexible catheter 29. The proximal end of the catheter 29 may include a suitable connection 20 for receiving the barrel 12. In other examples, the barrel 12 may be directly coupled to the injection needle 50. The syringe barrel 12 may function as a reservoir containing the composition or co-composition 15 for injection through the needle 50.

[0060] FIG. 1B illustrates an exemplary syringe 30 for use with an automatic injection system 45. The syringe 30 may include any of the features of the syringe 10 of FIG. 1A, such as a barrel 32, a plunger 34, and a luer adapter (or another suitable adapter / connector) at a distal end 38 of the barrel 32. A composition or co-composition 15 as described above may be loaded into the barrel 32, and the syringe 30 may be inserted into a channel 47 of the injection system 45 for automatic control over the amount of hydrogel injected. The distal end 38 of the syringe 30 may be coupled to an injection needle (e.g., similar to the injection needle 50 of FIG. 1A) via a catheter 39. According to some embodiments of the present disclosure, the plunger 34 may form part of the injection system 45, and the barrel 32 may be a separate component, such as a replaceable cartridge, that is connected to the injection system 45. For example, the composition or co-composition 15 may be prepared within the barrel 32 as a replaceable cartridge having a proximal attachment that fits with a plunger component of the injection system 45 .

[0061] FIG. 1C illustrates an exemplary reservoir 60 according to some embodiments of the present disclosure. The reservoir 60 may be provided by a flexible pouch or bag, such as an IV bag. The composition or co-composition 15 described herein may be loaded into the reservoir 60. The reservoir 60 may be sterile and may comprise a plastic material, such as polyvinyl chloride (PVC) (e.g., with a plasticizer, such as bis(2-ethylhexyl) phthalate (DEHP)) or a non-PVC plastic material. The pouch may include a luer adapter 63 for attachment to a catheter 69 and / or needle (having any suitable gauge size, as described above) for injecting the composition or co-composition 15 into a patient. The reservoir 60 may be compressible, for example, to allow delivery of the composition through the catheter 69 and / or needle by compression of the reservoir 60.

[0062] The amount of force required to move a composition or co-composition through a needle opening (commonly described as a "peak load" force) may depend on the viscosity of the composition or co-composition, the dimensions of the needle (inner diameter, outer diameter, and / or length), and / or the material from which the needle is made. For example, a greater amount of force may be applied to inject a composition or co-composition through a 33 gauge needle compared to a 7 gauge needle. Further factors that may affect the amount of force applied to inject a composition or co-composition may include the dimensions (inner diameter, outer diameter, and / or length) of the catheter connecting the reservoir to the needle. Peak loads suitable for one-handed or two-handed injection may range from about 5 lbf (22.24 N) to about 25 lbf (111.21 N), such as about 10 lbf (44.48 N) to about 20 lbf (88.96 N), such as about 15 lbf (66.72 N). The load measured for a given hydrogel concentration may vary for different needles and flow rates. An injection system having a mechanically driven plunger, such as that shown in FIG. 1B, may also be useful when higher peak load forces are required.

[0063] According to some embodiments of the present disclosure, the size of the needle may be selected based on the viscosity and / or components of the composition or co-composition, or vice versa. Additionally, the dimensions (inner diameter, outer diameter, and / or length) of the catheter tube may affect the type and amount of force, if any, applied to the composition or co-composition during injection. These parameters may be considered according to the properties of the composition or co-composition and the needs of the patient. According to some embodiments of the present disclosure, the size of the needle may be 23 gauge or 25 gauge. In some cases, the larger size of 20 gauge, 21 gauge, or 22 gauge may be used to inject the composition or co-composition.

[0064] The compositions or co-compositions described herein can be used in a variety of medical procedures, including tissue resection and ablation procedures of the GI system, respiratory system, and / or genitourinary system. The tissues resected or ablated in such medical procedures can include diseased or damaged tissues, non-diseased tissues, or combinations thereof. Exemplary tissue ablation procedures include endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), as described above. In these procedures, an endoscope is typically inserted into the patient's esophagus and advanced through the GI system to reach a target site in the esophagus, stomach, or intestine. EMR is typically used for the removal of tissues smaller than 2 cm in diameter, for example, to biopsy tissue or to remove damaged or diseased tissues (e.g., cancerous lesions), while ESD is typically used for the removal of larger lesions.

[0065] In some embodiments, the compositions or co-compositions described herein may be injected between two layers of tissue, for example, into the submucosal tissue between the upper mucosal layer and the lower muscularis propria at the target treatment site. The compositions or co-compositions may be injected into the submucosal space (submucosa) under a portion of tissue, such that the injected material separates the mucosal tissue from the muscularis propria and elevates the mucosal tissue layer. A suitable cutting device, for example, an electrocautery cutting device such as a knife, snare, scissors, or forceps, may then be used to remove the portion of tissue. For removal of a larger portion of tissue (e.g., via ESD), the compositions or co-compositions may be injected under the portion of tissue, and the hydrogel will lift the upper layer of tissue from the lower layer. The cutting device may then be used to create an incision around the portion of tissue and remove it. The compositions or co-compositions may be injected into the submucosal layer to assist in removing additional portions of tissue.

[0066] In various embodiments, the hydrogel maintains the separation of the tissue layers throughout the ablation procedure. Some of the hydrogel may be removed via the ablation process. However, at least a portion of the hydrogel will typically remain in place after the procedure in contact with one or more of the tissue layers, as discussed further below.

[0067] 2A-2E show an exemplary ablation procedure according to some embodiments of the present disclosure. For example, the procedure may be EMR or ESD as described above, or any other suitable medical procedure for ablating tissue. FIG. 2A shows a cross-sectional view of two portions of tissue or tissue layers 80, 82, which may be separated by an intermediate layer of tissue 81 (such as an upper mucosal layer and an underlying muscularis propria layer separated by an intermediate submucosa layer). One or both of the portions of tissue 80, 82 may include a section 85 of tissue targeted for removal. For example, the section 85 of tissue may include damaged or diseased tissue, or may include tissue targeted for biopsy and subsequent analysis. In the example of FIG. 2A, the section 85 of tissue is located toward the tissue surface, but the devices and compositions disclosed herein may be used to remove tissue from an inner tissue layer.

[0068] As shown in FIG. 2B, an endoscope 100 defining one or more lumens (e.g., three lumens as shown) may be used to deliver a needle 70 to a treatment site. The needle 70 may have a hollow lumen and a sharp beveled tip 72 for piercing the tissue surface such that the needle tip 72 is within the intermediate layer 81 between the upper and lower portions 80 and 82 of the tissue. The needle lumen may be in communication with a fluid reservoir, such as a syringe or other reservoir containing the composition or co-composition prepared as described above. The syringe may be used to inject the composition or co-composition into the intermediate layer 81 between the portions 80, 82 of the tissue to form a cushion or bleb of polysaccharide-based hydrogel 90, as shown in FIG. 2B. When the composition or combined co-composition is injected, a volume of polysaccharide-based hydrogel 90 (also referred to above as polysaccharide-based hydrogel at the site of administration) can separate upper and lower tissue portions 80, 82, thereby lifting tissue section 85 from the underlying tissue. An electrocautery snare 74 or other cutting device 74 (e.g., an electrocautery knife, scissors, or forceps, among other suitable cutting devices) can be used to cut and remove tissue section 85, as shown in Figures 2C and 2D.

[0069] As shown in FIG. 2E, when the section of tissue 85 is removed, a portion of the polysaccharide-based hydrogel 90 remains in place after the procedure in contact with one or more of the tissue layers 80, 81, 82. In this manner, the polysaccharide-based hydrogel 90 can act as a barrier (i.e., as a "band-aid") to protect the wound and / or to reduce or prevent blood flow after tissue resection or ablation until the polysaccharide-based hydrogel has biologically disintegrated. In some embodiments, the polysaccharide-based hydrogel 90 can also act as a depot for a hemostatic agent, allowing elution of the hemostatic agent during the procedure and / or over the post-operative period, providing an immediate and / or long-term therapeutic profile. EXAMPLES

[0070] Example 1 Raw materials: Orise® is commercially available from Boston Scientific Corporation (Marlborough, Massachusetts, USA). Gellan gum was provided as low acyl CG-LA grade Kelcogel® from CP Kelco US Inc. (Atlanta, Georgia, USA). Salts were prepared as calcium chloride and sodium chloride solutions in sterile water. Chitosan FD is lyophilized chitosan, more specifically electrosprayed particles of chitosan (acetate) crosslinked with tripolyphosphate (e.g., sodium tripolyphosphate) and subsequently lyophilized, and can be prepared according to Example 1 of US Patent Publication No. 2021 / 0322629.

[0071] Samples were ground and sieved to <50 μm. Hydroxyapatite nanopowder (<200 nm PSD, 97%) was provided by Aldrich (MilliporeSigma, St. Louis, MO, USA). Aminocaproic acid (ACA) (received as 6-aminohexanoic acid) was provided by Merck & Co. Inc., Branchburg, NJ, USA. Tranexamic acid (TXA) was provided by Merck as a pure powder. Ninhydrin powder (spectrophotometric grade) was provided by Merck.

[0072] Preformed Gel Preparations Composite loaded preformed hydrogels: Commercially available Orise® (polysaccharide-based) hydrogel was loaded into a small mixing vessel and stirred at 300 rpm. Composites (5% w / w chitosan FD (ground to <50 μm) or 10% w / w chitosan FD (ground to <50 μm) or 5% w / w hydroxyapatite (200 nm)) were added to the stirred hydrogel and mixed at room temperature for <10 min. Once mixing was complete, syringes (10 ml) were back-loaded and then stored under refrigeration.

[0073] Drug-loaded preformed hydrogels: Commercially available polysaccharide-based hydrogels were loaded into a small mixing vessel and stirred at 300 rpm. API drug powders (25% w / w aminocaproic acid or 15% w / w tranexamic acid) were added to the stirred hydrogel and mixed for <10 min at room temperature. Once mixing was complete, syringes (10 ml) were back-filled and then stored under refrigeration.

[0074] Pre-filled gel preparation Composite filled molded hydrogels (<1.5% GG w / w final composition): Gellan gum (polysaccharide) raw material was hydrated (2 hours, +70°C) and then cooled to 40°C. Once cooled, the composite (5% w / w chitosan FD (milled to <50 μm) or 10% w / w chitosan FD (milled to <50 μm) or 5% w / w hydroxyapatite (200 nm)) was added with stirring, followed by a solution of crosslinker salts (calcium chloride and sodium chloride). The mixture was stirred for a further <10 minutes before being back-filled into syringes (3 ml or 10 ml) and subsequently stored under refrigeration.

[0075] Attribute Test Injection Evaluation: Gel-filled syringes were tested using an Instron® Tensile Tester 5965 (Instron, Norwood, MA, USA) with the selected needle gauge (18G or 19G) or an Interject™ drug delivery catheter (Boston Scientific). Injectability testing was performed at 2.36 mm / s with a travel distance of 20 mm. Equipped with a 100 N force gauge, the prototypes were benchmarked against the commercially available Orise®.

[0076] [Table 1]

[0077] The results demonstrated successful and significant maximum injection forces for compositions containing 5% hydroxyapatite at <200 nm. Chitosan FD at levels of 5% and 10% exceeded the 100 N limit of the device. This observation led to the conclusion that the composite material is preferably of particle size around 200 μm.

[0078] Kinetic Drug Release: Drug-loaded prototypes (1 g) were loaded into 6-well transwell plates containing 6 ml D-PBS (Dulbecco's Phosphate Buffered Saline) and stirred at 100 rpm (rotary incubator) at 37°C. 500 μl aliquots of supernatant were extracted at 0 h, 2 h, 4 h, and 24 h (extracted supernatant was supplemented with 500 μl DPBS). 20 μl of supernatant was added to 100 μl of 2% w / w ninhydrin solution. The combined solution was heated (+70°C, >10 min) until a purple color appeared. The solution was cooled to room temperature and 500 μl of ethanol was added. 100 μl aliquots of the final purple solution were transferred to a 96-well UV-transparent well plate and analyzed at 570 nm using a BioTek Epoch UV plate reader (Agilent Technologies, Santa Clara, CA, USA). Recovery results were determined against comparative drug calibration curves.

[0079] Prepare 2% ninhydrin solution: 2% ninhydrin powder in 50:50 ethanol:0.05% glacial acetic acid. Calibration curves were prepared with target concentrations of 60, 30, 15, 7.5 mg / ml of drug (ACA or TXA) in D-PBS. 20 μl aliquots were added to 100 μl of 2% ninhydrin solution. The combined solution was heated (+70°C, >10 min) until a purple color appeared. The solution was cooled to room temperature and 500 μl of ethanol was added. 100 μl aliquots of the final purple solution were transferred to a 96 UV-transparent well plate and analyzed at 570 nm.

[0080] Kinetic drug release analysis showed an average recovery of <80% of 6-aminocaproic acid in the D-PBS supernatant within 2 hours of drug administration (see Figure 3), demonstrating adequate gel loading, on-demand drug administration, and immediate dissolution for the amino acid drug.

[0081] Kinetic drug release analysis showed an average recovery of <70% of tranexamic acid in the D-PBS supernatant within 2 hours of drug administration (see Figure 4), demonstrating adequate gel loading, on-demand drug administration, and immediate dissolution with additional amino acid drug.

[0082] Example 2 Chitosan FD (lyophilized, electrosprayed particles of chitosan acetate cross-linked with tripolyphosphate) with a mean particle size of approximately 5000 nm was prepared by ball milling 80 mg of chitosan FD in hexane, zirconium microbeads (1.4 mm, 20 g) in a P7 planetary mill (e.g., Fritsch PULVERISETTE planetary ball mill, FRITSCH Milling and Sizing, Inc., Pittsboro, NC, USA) at 400 rpm for 10 min.

[0083] Spray-dried particles with chitosan cores coated with tripolyphosphate were produced. Chitosan particles were prepared as follows. Chitosan solution (ultra-high molecular weight chitosan dissolved in aqueous acetic acid) and aqueous tripolyphosphate were spray-dried in a Buchi B-290 Mini Spray Dryer (BUCHI Corporation, New Castle, Delaware, USA) equipped with a three-fluid nozzle. Aqueous chitosan-acetate was fed to the inner fluid nozzle and aqueous tripolyphosphate was fed to the outer fluid nozzle to create a core / shell structure with a chitosan core and a tripolyphosphate shell (where the chitosan is cross-linked by the tripolyphosphate to the extent that the chitosan and tripolyphosphate intermix at the interface). The outlet temperature is set at a relatively low 49°C to reduce the risk of degradation. Figure 5 shows a micrograph of a core / shell particle produced by this method. FIG. 6 is a graph showing particle size distribution, volume density (%) vs. particle size (μm), measured by a Malvern Mastersizer® (Malvern Instruments, Malvern, UK) for particle aggregates produced according to the procedure described above.

[0084] Commercially available Orise® hydrogel was loaded into a small mixing vessel and stirred at 300 rpm. Chitosan FD, 5% w / w, was added to the stirred hydrogel and mixed at room temperature for <10 minutes. Once mixing was complete, syringes (10 ml) were back-filled and then stored under refrigeration.

[0085] The gel-filled syringes were tested as described above using an Instron® Tensile Tester 5965 and a 23G Interject™ drug delivery catheter. The prototypes were evaluated against the commercially available Orise®.

[0086] [Table 2]

Claims

1. An injectable polysaccharide-based hydrogel comprising an anionic polysaccharide, a cationic crosslinker and a hemostatic agent.

2. The injectable polysaccharide-based hydrogel of claim 1 , wherein the anionic polysaccharide comprises repeating units of glucuronic acid.

3. The injectable polysaccharide-based hydrogel of claim 1 , wherein the anionic polysaccharide comprises gellan gum.

4. 4. The injectable polysaccharide-based hydrogel according to any one of claims 1 to 3, wherein the anionic polysaccharide is provided at a concentration ranging from about 0.05% to about 1.0%, based on the total weight of the injectable polysaccharide-based hydrogel.

5. The injectable polysaccharide-based hydrogel of any one of claims 1 to 4, wherein the cationic crosslinker comprises a salt containing a divalent metal cation.

6. 6. The injectable polysaccharide-based hydrogel of claim 1, wherein the cationic crosslinking agent is provided at a concentration ranging from about 0.01% to about 0.25% based on the total weight of the injectable polysaccharide-based hydrogel.

7. The injectable polysaccharide-based hydrogel of any one of claims 1 to 6, wherein the hemostatic agent is selected from organic polymeric hemostatic agents, small molecule organic hemostatic agents, large molecule organic hemostatic agents, and inorganic hemostatic agents.

8. The injectable polysaccharide-based hydrogel according to any one of claims 1 to 7, wherein said hemostatic agent is in particulate form and has an average particle size of less than 50,000 nm.

9. 9. The injectable polysaccharide-based hydrogel of claim 8, wherein the hemostatic agent comprises a core comprising a chitosan salt and a shell comprising a polyanionic crosslinker.

10. 10. The injectable polysaccharide-based hydrogel of claim 1, wherein the hemostatic agent is provided at a concentration ranging from about 5% to about 50% based on the total weight of the injectable polysaccharide-based hydrogel.

11. A medical device comprising a reservoir containing an injectable polysaccharide-based hydrogel according to any one of claims 1 to 10.

12. The medical device of claim 12 , wherein the reservoir is a syringe barrel.

13. The medical device of claim 13 , further comprising a needle through which the injectable polysaccharide-based hydrogel is injected.

14. 15. Use of the medical device according to claim 14 in a medical procedure in which an upper mucosal layer is lifted from a lower layer.

15. A kit comprising a medical device according to any one of claims 11 to 13 and one or more items selected from (a) an endoscopic injection needle, (b) a tissue resection device, (c) a tissue retrieval device, and (d) an endoscope, in suitable packaging material.

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