FIG. 2.

Chondrogenic differentiation of hBMSCs in an osteochondral environment in vitro is mediated by the subchondral bone. (A) Schematic representation of bovine cartilage-only and bone-only biopsies with a simulated defect containing hBMSCs in alginate; (B) Collagen type 2 and aggrecan gene expression relative to GAPDH of hBMSCs from two different donors in alginate cultured in bone-only biopsies, cartilage-only biopsies, or simulated subchondral defects in osteochondral biopsies (n=6 per hBMSC donor, generalized estimated equations model with correction for multiple testing); (C) TGFβ1 secretion of bone-only, cartilage-only, or osteochondral biopsies measured in culture medium used for 72 h after 28 days of culture in total (n=3, mean with standard deviation); (D) Collagen type 2 and aggrecan gene expression relative to GAPDH of hBMSCs from one donor cultured for 28 days in alginate beads with or without supplementing TGFβ or in alginate in simulated subchondral defects in osteochondral biopsies (norm.) or in devitalized osteochondral biopsies (dead) (n=6, mean with standard deviation, Student's t-test). Color images available online at www.liebertpub.com/tea