Figure 5. Effects of prolonged in vitro culture expansion on DPPC differentiation capabilities.

Effects of prolonged in vitro culture expansion on DPPC differentiation capabilities.  (A) Osteogenic differentiation potential of high proliferative capacity, A3, was greatly reduced following culture expansion from 30 PDs, to 62 PDs and 75 PDs; apparent by a reduction in alizarin red staining and the loss of osteogenic marker Runx2, osteocalcin (OCN) and osteopontin (OPN) expression (right panel).  (B) Loss of A3 osteogenic differentiation potential was concomitant with the increased presence of enlarged intracellular lipid vesicles (Oil Red O staining) and the increased expression of early and late adipogenic markers, PPARγ and lipoprotein lipase (LPL, right panel).  No staining was observed in control cultures in the absence of osteogenic or adipogenic media.  Scale bars = 100 µm.