Fig. 3

Mean changes in the relative expression of chondrogenic and hypertrophic marker genes ± standard deviation as measured by RT-qPCR in mesenchymal progenitor cells at the end of the chondrogenic differentiation period. Mesenchymal stromal cells (MSCs) derived from bone marrow of five different patients were incubated with chondrogenic differentiation medium containing 500 ng/ml and 1000 ng/ml of the mutant R57A, 500 ng/ml and 1000 ng/ml of growth and differentiation factor 5 (GDF-5) or transforming growth factor beta (TGF-β)1 for 21 days for 21 days. Untreated cultures treated with standard cell culture medium were maintained as negative controls. The mean changes in the relative expression of the chondrogenic (a) marker genes—collagen type II (Collagen II) and sex-determining region Y-type high-mobility-group-box (SOX) 9—as well as the hypertrophic (b) marker genes—collagen type X (Collagen X) and alkaline phosphatase (ALP)—are pictured, respectively. Error bars represent the range of changes in the mean expression of specific marker genes in differentiated cell cultures from which the standard deviations were calculated. Elongation factor 1α (EEF1α) was used as the housekeeping gene and for internal controls. Primer details are illustrated in Table 1. Asterixis (*) represent significant differences (P < 0.05) compared to negative control samples at this particular time. The respective group of pictured bars refer to MSCs treated as controls, with R57A 500 ng/ml, with R57A 1000 ng/ml, with GDF-5 500 ng/ml, with GDF-5 1000 ng/ml and TGF-ß1 10 ng/ml (from left to right). RT-PCR was performed using BMSCs derived from five different donors (n = 5) and each experiment was performed in triplicate or quadruplicate (n = 3 to 4). d, days; GDF-5, growth and differentiation factor 5; TGF-ß, transforming growth factor beta