The Use of Collagen with High Concentration in Cartilage Tissue Engineering by Means of 3D-Bioprinting

3D-bioprinting is a promising technology for a tissue scaffold fabrication in the case of damaged tissue/organ replacement. Collagen is one of the most appropriate hydrogel for the purpose, due to its exceptional biocompatibility. However, the use of collagen with conventionally low concentration makes bioprinting process difficult and does not provide its high accuracy. The purpose of the study was evaluation of suitability of collagen with high concentration in case of chondrocyte-laden scaffold fabrication via 3D-bioprinting for cartilage regeneration in vitro and in vivo. The results of the study showed that inherent porosity of 4% collagen was not enough for cell survival in the case of long-term incubation in vitro. With the beginning of the scaffold incubation, cell migration to the surface and out of the scaffold was observed. The residual cells died mostly within 4 weeks. As for in vivo study, in 2 weeks after implantation of the scaffold, a weak granulomatous inflammation was observed. In 6 weeks, a connective tissue was formed in the area of implantation. In the tissue, macrophages and groups of small cells with round nuclei were found. In accordance with morphological criteria, these cells could be considered as young chondrocytes. However, its amount was not enough to initiate the formation of cartilage.