Chitosan (Chit) is a promising material, as it possesses the properties necessary for tissue engineering structures. Chit is a biodegradable, biocompatible natural polymer. Based on Chit scaffolds with specified physicochemical properties can be obtained, for example, by modifying chitosan by amino groups¹. Improvement of mechanical properties, as well as regulation of the rate of biodegradation and hydrophilic-hydrophobic balance, can be achieved by copolymerization of chitosan with other monomers / oligomers. Polylactic acid (PLA) meets the requirements of tissue engineering for biomaterials due to its biocompatibility and the possibility of obtaining scaffolds with the required morphology on its basis. PLA is one of the few synthetic polymers used clinically. However, the hydrophobic nature of PLA and the lack of functional groups limit cell adhesion, and slow biodegradation limits the use of PLA scaffolds. The creation of copolymers based on chitosan and oligolactides will allow combining the advantages and leveling the disadvantages of each component.
The purpose of this work is to obtain polymer matrices in the form of films (2D) and microporous hydrogels (3D) based on chitosan, as well as its graft copolymers with oligolactides, the study of their structure, physicochemical properties, as well as the growth and differentiation of cells on / in them in an in vitro model. For the formation of films and hydrogels, we used copolymers of chitosan, (MW 60 kDa, SD 0.9), with oligo (L, L- and / L, D-lactides) with MW 5 kDa, (Chit-L, L and Chit-L, D, respectively), which were obtained by the method of solid-phase synthesis². Films (2D) were obtained from copolymer solutions by pouring, and 3D macroporous hydrogels - by lyophilization of these solutions. The structure of the hydrogels was studied by confocal laser microscopy and represented a system of interconnected micropores with an average size of 120-140 μm. The cytotoxicity of the obtained scaffolds was tested after incubation with the culture medium for 24 h by examining the toxicity of the obtained extracts, using the MTT test. It was shown that the surface of the modified scaffolds ensured adhesion of mouse fibroblast L929 cells (confocal microscopy), as well as their growth and proliferation during long-term cultivation in hydrogels (MTT test). During the cultivation of human mesenchymal stromal cells (MSC) isolated from adipose tissue, it was found that hydrogels provide the conditions necessary for cell proliferation, and copolymer films promote their differentiation in the osteo direction. MSC differentiation was assessed by the activity of alkaline phosphatase.
Thus, hydrogels based on copolymers of chitosan with oligolactides are promising biomaterials for regenerative medicine.