Biocompatible and bioabsorbable derivatized chitosan compositions
Inventors
McGrath, Barbara • McCarthy, Simon • KUHN, Sam • Wold, Alysha • Stolten, Michael • Bennett, Amanda
Assignees
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Publication Number
US-10709817-B2
Publication Date
2020-07-14
Expiration Date
Abstract
The invention relates to biocompatible, bioabsorbable derivatized non-crosslinked chitosan compositions optionally crosslinked to gelatin/collagen by 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) for biomedical use and methods of making and testing such compositions, including a modified acute systemic toxicity test. The compositions comprise derivatized chitosan reacetylated to a degree of N-deacetylation (DDA) of between about 15% and 40%. The compositions are typically bioabsorbed in about 90 days or less and can be made to bioabsorb at differing rates of speed. The compositions are initially soluble in aqueous solution below pH 6.5. The compositions have an acid content that can be adjusted between about 0% (w/w) and about 8% (w/w) to customize the composition for uses that require and/or tolerate differing levels of cytotoxicity, adhesion, composition cohesion, and cell infiltration into the composition.
Core Innovation
The invention provides a biocompatible, bioabsorbable, deacetylated and reacetylated reduced amine functionality chitosan composition. The composition has a degree of N-deacetylation between about 15% and 40% and an acid content between about 2% (w/w) and 8% (w/w), with reduced amine functionality directed to modulate biological response, including cytotoxicity, adhesion, cohesion, and cell infiltration.
The chitosan is reacetylated and characterized by aqueous solubility behavior, including initial solubility in an aqueous solution at or below about pH 6.5. The acid content is adjustable, including an acid content between about 0% and 8% (w/w), to tune cytotoxicity, adhesion, cohesion, and cell infiltration, while maintaining lamella preservation and cellular infiltration at low acid. The composition can additionally be cross-linked with gelatin and/or collagen, including EDC-crosslinked gelatin to chitosan.
The invention also includes a method of making the composition by obtaining deacetylated chitosan, producing reacetylated chitosan having a molecular weight of at least about 90 kDa to about 170 kDa from the deacetylated chitosan with a degree of N-deacetylation between about 15% and 40%, and resolubilizing the reacetylated chitosan to aqueous solution using carbonic acid. Reported evaluation includes a modified acute systemic toxicity assessment (Mouse Lesion Test) that predicts IL-1β-mediated systemic inflammatory toxicity and atopic-dermatitis-like lesions, with correlations reported between DDA level and lesion severity as well as bioabsorption and IL-1β upregulation.
Claims Coverage
Two independent claims are present: one covers a specific chitosan composition defined by N-deacetylation degree and acid content, and one covers a method of making the specified composition, including reacetylation to a defined molecular weight range and resolubilizing using carbonic acid.
Deacetylated and reacetylated reduced amine functionality chitosan composition
A biocompatible, bioabsorbable, deacetylated and reacetylated reduced amine functionality chitosan composition having a degree of N-deacetylation of between about 15% and 40% and an acid content between about 2% (w/w) and 8% (w/w).
Initial solubility at or below pH 6.5
The composition is initially soluble in an aqueous solution at or below about pH 6.5.
Gelatin or collagen cross-linking
The composition is cross-linked with at least one of gelatin and collagen.
Chitosan-to-gelatin ratio selections
The ratio of chitosan to gelatin is selected from about 1:1, about 2:1, and about 3:1.
In vivo bioabsorption timeframe
The composition is capable of in vivo bioabsorption selected from less than about 90 days, about 60 days, about 30 days, and about 14 days.
Selected N-deacetylation sub-ranges
The composition has a degree of N-deacetylation selected from about 15% to 35%, about 20% to 35%, and about 20% to 30%.
Method using deacetylation, reacetylation, and carbonic acid resolubilization
A method of making a biocompatible, bioabsorbable chitosan composition comprising obtaining deacetylated chitosan, producing reacetylated chitosan having a molecular weight of at least about 90 kDa to about 170 kDa from the deacetylated chitosan having a degree of N-deacetylation of between about 15% and 40%, and resolubilizing the reacetylated chitosan to aqueous solution using carbonic acid.
Starting-material selection for N-deacetylation and purity
The method further includes selecting a chitosan starting material that has been deacetylated and reacetylated and that meets specified N-deacetylation and purity requirements.
Reducing free amine functionality using an electrophile
The method further reduces the free amine functionality of deacetylated and reacetylated chitosan by reducing the glucosamine C-2 nitrogen using an electrophile.
Cross-linking with gelatin or collagen
The method includes cross-linking chitosan with gelatin or collagen.
EDC cross-linking agent
The method further includes using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride to accomplish cross-linking.
Processing into selected composition formats
The method further processes chitosan into a selected composition selected from freeze-dried sponge, foam, implant, tissue scaffold, implant device surface coating, matrix, fiber, powder, sheet, film, membrane, nanofiber, nanoparticle, or hydrogel.
Across the two independent claims, the coverage centers on a biocompatible, bioabsorbable deacetylated and reacetylated reduced amine functionality chitosan composition defined by degree of N-deacetylation and acid content, and a making method that obtains deacetylated chitosan, reacetylates to a defined molecular-weight range from a specified N-deacetylation starting material, and resolubilizes in aqueous solution using carbonic acid. Dependent features further define solubility at acidic pH, optional gelatin/collagen cross-linking, in vivo bioabsorption time ranges, and multiple selectable final formulation formats.
Stated Advantages
Predicts IL-1β-mediated systemic inflammatory toxicity and atopic-dermatitis-like lesions in vivo for higher DDA chitosans.
Compositions at about 35% DDA show rapid bioabsorption without IL-1β upregulation.
Adjustable acid content tunes cytotoxicity, adhesion, cohesion, and cell infiltration.
Low acid supports lamella preservation and cellular infiltration.
Cross-linked compositions are described as supporting hemostatic efficacy compared relative to Surgicel™.
Modified acute systemic toxicity testing (Mouse Lesion Test) discriminates acceptable versus toxic DDA ranges.
Documented Applications
Use of the modified acute systemic toxicity assessment (Mouse Lesion Test) to predict IL-1β-mediated systemic inflammatory toxicity and atopic-dermatitis-like lesions observed in vivo.
Implantation studies, including in vivo rat intraperitoneal implantation, to evaluate lesion severity correlations with DDA and amine functionality state.
Evaluation of absorption, biocompatibility, and hemostasis in 28-day rat studies, including comparison to Surgicel™.
Hemostatic evaluation in swine bleeding models, including heparinized bleeding and aorta perforation, reporting hemostatic efficacy for about 35% DDA compositions.
Evaluation of simulated arterial wound sealing (SAWS).
Use of lysozyme susceptibility evaluation, including in vitro lysozyme susceptibility, to assess dependence on DDA.
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