Cartilage tissue engineering by collagen matrix associated bone marrow derived mesenchymal stem cells

In this study we compared the in vitro formation of cartilaginous grafts composed of collagen type I hydrogel with both ovine primary articular chondrocytes (AC) and bone marrow derived mesenchymal stem cells (MSC). During 4 weeks of culture, aggregate properties were quantitatively verified, cell viability and the expression of cartilage markers were assayed. Different microscopic techniques indicated a subdivision of MSC based scaffolds into a central construct region with uniformly distributed stem cells with low levels of apoptosis, and peripheral layers of proliferative cells, which undergo differentiation. Immunohistochemical staining and quantitative measurements of sulfated glycosaminoglycans (s-GAG) of MSC hydrogels showed a significant increase in matrix deposition, mainly in outer areas. Furthermore, semi-quantitative RT-PCR of MSC specimens reflected a constant collagen type I activity with enhanced collagen type II, aggrecan and Sox9 expression which would suggest hyaline-like cartilage formation. We propose the application of MSC seeded grafts for the repair of focal cartilage lesions.