FGF-2–induced proliferation of normal and Hurler MAPCs. Normal or Hurler MAPCs were cultured for 24 hours in absence or presence of a range of concentrations of FGF-2. The numbers of cells present in each well were determined as detailed in “Materials and methods.” Cell numbers are expressed as a ratio (number of cell in wells supplemented with FGF-2–number of cells in absence of FGF-2). (A) Proliferation of normal and Hurler MAPCs in the absence or presence of the indicated concentrations of FGF-2. In separate wells in the same experiments, normal MAPCs were cultured in presence of 50% CM from Hurler MAPCs. n = 4 to 6 independent experiments with replicates. Comparison between normal MAPCs and the other conditions: ^*P < .01, ¶P < .005, §P < .002, ^**P < .001. (B) Proliferation of heparitinase I– and III–treated normal MAPCs, in the absence or presence of 50% CM from normal or Hurler MAPCs, was examined as in panel A. n = 3 independent experiments with replicates. Comparison between proliferation seen in presence of normal versus Hurler CM: §§P < .05, ¶P < .005, §P < .002. (C) Proliferation of heparitinase I– and III–treated Hurler MAPCs, in the absence or presence of 50% CM from normal or Hurler MAPCs, was examined as in panel A. n = 3 independent experiments with replicates. Comparison between proliferation seen in presence of normal versus Hurler CM: §§P < .05, ^*P < .01, §P < .002, ^**P < .001.