Multiphasic collagen fibre–PLA composites seeded with human mesenchymal stem cells for osteochondral defect repair: an in vitro study

A promising approach for the repair of osteochondral defects is the use of a scaffold with a well‐defined cartilage–bone interface. In this study, we used a multiphasic composite scaffold with an upper collagen I fibre layer for articular cartilage repair, separated by a hydrophobic interface from a lower polylactic acid (PLA) part for bone repair. Focusing initially on the engineering of cartilage, the upper layer was seeded with human mesenchymal stem cells (hMSCs) suspended in a collagen I hydrogel for homogeneous cell distribution. The constructs were cultured in a defined chondrogenic differentiation medium supplemented with 10 ng/ml transforming growth factor‐β1 (TGFβ1) or in DMEM with 10% fetal bovine serum as a control. After 3 weeks a slight contraction of the collagen I fibre layer was seen in the TGFβ1‐treated group. Furthermore, a homogeneous cell distribution and chondrogenic differentiation was achieved in the upper third of the collagen I fibre layer. In the TGFβ1‐treated group cells showed a chondrocyte‐like appearance and were surrounded by a proteoglycan and collagen type II‐rich extracellular matrix. Also, a high deposition of glycosaminoglycans could be measured in this group and RT–PCR analyses confirmed the induction of chondrogenesis, with the expression of cartilage‐specific marker genes, such as aggrecan and collagen types II and X. This multiphasic composite scaffold with the cartilage layer on top might be a promising construct for the repair of osteochondral defects. Copyright © 2009 John Wiley & Sons, Ltd.