Seven diverse chondrogenic progenitor cell lines

The limited regenerative capacity of cartilage, tendon and aged bone underlies the chronic nature of many age-related degenerative diseases of skeletal tissues. Bone maintains a regenerative capacity through the activation, proliferation and differentiation of bone mesenchymal stem cells (MSCs); however, this activity declines with age [1]. On the other end of the spectrum, cartilage shows almost no postnatal regenerative capacity. The rising incidence of age-related degenerative diseases in these tissues, including osteoarthritis, intervertebral disc disease and osteoporosis, has led to an increased emphasis on strategies for repair employing exogenous cell-based formulations. Current challenges include the need for protocols for generating cells of the connective tissues in a reproducible and scalable manner with a high level of purity and site-specific identity. The use of MSCs to supply these needs has been the focus of extensive study to date [2,3]; however, despite reports of the transgermal plasticity of MSCs [4–6], rigorous clonal data demonstrating differentiation beyond hypertrophic chondro cytes, osteoblasts, adipocytes, fibroblasts and reticular cells are largely lacking [7]. In addition, MSCs also typically differentiate into transient hypertrophic chondrocytes as opposed to permanent definitive chondrocytes when differentiated using Seven diverse human embryonic stem cell-derived chondrogenic clonal embryonic progenitor cell lines display site-specific cell fates