Abstract
While cartilage has very limited self-regeneration capacity, and the source of chondrocytes is limited harvesting, mesenchymal stem cells (MSCs) provide an attractive substitute of cartilage tissue engineering as the precursor or progenitor cells that possess the ability to differentiate into functional chondrocytes without ethical and moral concerns. In order to promote re-differentiation without dedifferentiation of chondrocytes as well as to prevent the cell hypertrophy while MSCs tend to undergo chondrogenic differentiation, co-culture strategies were used in this study, and we establish a co-culture system (monolayer and 3D non-contact) of human (rabbit) chondrocytes and human MSCs without any other growth factors to observe the paracrine stimulation effect between these two cells. Therefore, we explore whether MSCs could be promoted chondrogenesis or chondrocytes could be stimulated toward normal functional phenotype (re-differentiation) by so-called trophic effect of MSCs. After the CM-culture (chondrocyte-cultured medium for MSCculturing) and the 3D non-contact co-culture, MSCs gradually loss the chondrogenic phenotype along with culture days while the more stable chondrogenic phenotype of chondrocytes. But the exchange of soluble factors between these two cells makes MSCs produce cartilage-like ECM (GAGs). On the other hand, the direct co-culture shows the gradual enhancement of chondrogenic phenotype oh MSCs.