FIG. 5.
Expression of PTH/PTHrP receptor (PTH1R), Indian hedgehog (IHH), MMP13, and alkaline phosphatase (ALP) enzyme activity. Pellets received chondrogenic medium alone (ctrl) or were additionally stimulated with 2.5 nM PTHrP(1–34) either constantly (PTHrP const.) or intermittently (PTHrP pulse). (A–D) RNA was extracted from MSC pellets and mRNA levels were determined using quantitative real-time PCR as described for Figure 3. (A) Time course analysis of PTH1R expression. (B) Correlation of PTH1R mRNA expression levels of samples of the PTHrP pulse group with the stimulation of COL2A1 mRNA levels of the pulse group relative to COL2A1 mRNA levels of the control group (COL2A1 pulse group – COL2A1 control group, ΔCOL2A1). Shown are the single values of four independent experiments grouped by the indicated time points (n=16). r2=0.902, P<0.01, Pearson's correlation. (C, D) IHH (B) and MMP13 (C) expression at day 42. (E) ALP enzyme activity was measured in culture supernatants conditioned for 2 days each. (A, C–E) Values are given as the mean±SD of 10 (IHH and ALP) or 4 (MMP13 and PTH1R) independent experiments. *P≤0.05, **P≤0.01 versus control, Wilcoxon test. MMP13, matrix metalloproteinase.