Sequential differentiation of mesenchymal stem cells in an agarose scaffold promotes a physis-like zonal alignment of chondrocytes.

Chondrocytes of the epiphyseal growth plate (physis) differentiate and mature in defined linear zones. The current study examines the differentiation of human bone marrow derived mesenchymal stem cells (hBMSCs) into zonal physeal cartilage. hBMSCs were embedded in an agarose scaffold with only the surface of the scaffold in direct contact with the culture medium. The cells were differentiated using a two-step system involving the sequential addition of TGFß followed by BMP2. The resultant samples displayed a heterogenic population of physis-like collagen type 2 positive cells including proliferating chondrocytes and mature chondrocytes showing hypertrophy, expression of early bone markers and matrix mineralization. Histological analysis revealed a physis-like linear zonal alignment of chondrocytes in varying stages of differentiation. The less mature chondrocytes were seen at the base of the construct while hypertrophic chondrocytes and matrix mineralization was observed closer to the surface of the construct. The described differentiation protocol using hBMSCs in an agarose scaffold can be used to study the factors and conditions that influence the differentiation, proliferation, maturation, and zonal alignment of physeal chondrocytes.

Immunohistochemical analysis of human mesenchymal stem cells differentiating into chondrogenic, osteogenic, and adipogenic lineages.

Mesenchymal stem cells (MSCs) are multipotent cells that have the potential to differentiate into various mesenchymal lineages in vitro and in vivo. Due to their availability from tissues such as bone marrow, synovium, fat, and muscle, and their highly proliferative capacity, MSCs have evoked interest as a potential cell source for repair and regeneration of various types of tissues. Characterization by the expression of a panel of surface markers and the ability of MSCs to undergo multilineage differentiation is the benchmark for identifying this stem cell population. In this chapter, the protocols for the differentiation of MSC to chondrogenic, osteogenic, and adipogenic lineages and histological and immunostaining protocols for confirming trilineage differentiation of the MSC cells are described.