Effect of different growth factors on the chondrogenic potential of human bone marrow stromal cells

Objective: The aim of this study was to investigate the effects of differen t growth factors on the chondrogenic potential of human bone marrow stromal cells (BMSC). Design: Different growth factors which have been shown to sustain the osteo genic potential of BMSC during their 'in vitro' expansion were assayed for the maintenance of the chondrogenic potential. We compared the ability of B MSC to reconstitute cartilage in vitro with their ability to form bone on h ydroxyapatite microporous particles in an ectopic bone formation assay. Results: Among the factors assayed, fibroblast growth factor 2 (FGF2) was t he most effective in promoting growth of BMSC 'in vitro'. For all growth fa ctors tested, we have found a complete overlap of the enhancement of chondr ogenic and osteogenic potential. Any factor, either promoting or depressing bone formation, exerted the same effect on the chondrogenic potential of h uman BMSC. In particular, FGF2, either alone or in combination with other f actors, strongly supported the formation of bone as well as of cartilage. Conclusions: We conclude that FGF2 maintains human BMSC in an immature stat e allowing their 'in vitro' expansion. Expanded cells retain the chondro- o steogenic potential. Interestingly, the chondrogenic potential of BMSC 'in vitro' is directly related to their ability to form bone 'in vivo'. BMSC ex panded 'ex vivo' are presently being proposed for cell therapy of bone defe cts. 'In vitro' chondrogenesis may be regarded as a rapid prediction assay to assess cell ability to form bone after 'in vivo' transplant. (C) 2001 Os teoArthritis Research Society International.