Engineering of cell-laden gelatin-based microcapsules for cell delivery and immobilization in regenerative therapies

Abstract

Cell-based therapies often face the challenge of low cell retention and viability upon transplantation. Hence, biomaterials, which can immobilize transplanted cells, while at the same time support cell viability, are essential for successful clinical application. Noteworthy, biomaterials in the micrometer range such as microcapsules have the advantage of a minimally invasive introduction into tissue. Hence, we established an approach to generate gelatin-based cell carriers in the form of microspherical hydrogels. Fibroblasts were microencapsulated in glycidylmethacrylate (GMA)-functionalized gelatin by photopolymerization. While the degree of GMA-functionalization was kept constant, the hydrogel cross-linking density was adjusted by varying the time of irradiation, or the average gelatin-chain length. Stable microcapsules could be achieved with 10 wt% GMA-gelatin solutions for all irradiation periods tested (0.5 –2 min). Evaluation of cell viability revealed that microgels with the same weight content of biopolymer but with decreased cross-linking densities and thus decreasing storage, and E moduli resulted in best cell support. Noteworthy, encapsulated cells partially migrated out of the microcapsules and attached to the spherical surface. 10 wt% GMA-gelatin-based hydrogels with E moduli properties comparable to the native cellular niche proved to be a promising biomaterial suitable for the production of cell-laden microcapsules and shall be evaluated further for biomedical application.