Human Bone Marrow Stem Cell pH Modulation

hBMSCs were purchased from Lonza (Walkersville, MD, USA) and cultured in alpha-Modified Eagle Medium (Invitrogen, Carlsbad, CA, USA) containing 15% fetal bovine serum (FBS, Invitrogen), 100 mM L-ascorbic acid 2-phosphate (Wako Pure Chemical Industries, Osaka, Japan), 1% penicillin and streptomycin (Sigma), and 1% L-glutamine (Invitrogen). Media were titrated to pH 7.4, pH 6.8, or pH 6.4 by adding 20 mM HEPES and 1 M HCl, as described previously [10 (link),16 (link)]. Media were retitrated after incubation for 24 h, before using in the experiments. Cells were then cultured under different pH conditions for 48 h, before analysis of the stem cell characteristics and functions.