Fig. 1.
Low oxygen tension (3%) increases cell proliferation rate in both young and old MPCs. (A) Cell proliferation rate was measured in young and old MPCs under 3 and 21% O2 conditions. Young MPCs are represented by circles: black for 3% O2 and pinstriped for 21% O2. Old MPCs are represented by triangles: white for 3% O2 and gray for 21% O2. The insert in this figure shows the quantization of the cell proliferation rate at the eighth day of the culture. Each point represents the mean±SE of 3 determinations performed in three independent experiments. Statistical significance is marked as follows: ⁎Different from YM 21% O2; p<0.05; #Different from OM 21% O2; p<0.05; &Different from YM 3% O2; p<0.05. (B) High oxygen conditions (21%) decrease MPC differentiation. After 2 weeks at 3% or 21% O2, FBS 10% was replaced for horse serum 2% for 6 days to induce myotube differentiation. Representative photographs were obtained with a Zeiss microscope and a color camera Nikon Ds (magnification 4×); i: YM 3%; ii: YM 21%; iii: OM 3%; iv: OM 21%. n=3.