Abstract
Bone marrow mesenchymal stem cells (BM‐MSCs) and adipose‐derived progenitor cells (ADPCs) are potential alternatives to autologous chondrocytes for cartilage resurfacing strategies. In this study, the chondrogenic potentials of these cell types were compared by quantifying neo‐tissue synthesis and assaying gene expression and accumulation of extracellular matrix (ECM) components of cartilage. Adult equine progenitor cells encapsulated in agarose or self‐assembling peptide hydrogels were cultured in the presence or absence of TGFβ1 for 3 weeks. In BM‐MSCs‐seeded hydrogels, TGFβ1 stimulated ECM synthesis and accumulation 3–41‐fold relative to TGFβ1‐free culture. In ADPC cultures, TGFβ1 stimulated a significant increase in ECM synthesis and accumulation in peptide (18–29‐fold) but not agarose hydrogels. Chromatographic analysis of BM‐MSC‐seeded agarose and peptide hydrogels cultured in TGFβ1 medium showed extensive synthesis of aggrecan‐like proteoglycan monomers. ADPCs seeded in peptide hydrogel also synthesized aggrecan‐like proteoglycans, although to a lesser extent than seen in BM‐MSC hydrogels, whereas aggrecan‐like proteoglycan synthesis in ADPC‐seeded agarose was minimal. RT‐PCR analysis of TGFβ1 cultures showed detectable levels of type II collagen gene expression in BM‐MSC but not ADPC cultures. Histological analysis of TGFβ1‐cultured peptide hydrogels showed the deposition of a continuous proteoglycan‐ and type II collagen rich ECM for BM‐MSCs but not ADPCs. Therefore, this study showed both protein and gene expression evidence of superior chondrogenesis of BM‐MSCs relative to ADPCs. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:322–331, 2008