Whole-Cell Recording of hBMSCs

For whole-cell recordings, pipettes are filled with internal solution containing the following components: 145 mM KCl, 5 mM H-Hepes, 10 mM EGTA, 5 mM adenosine triphosphate–Na, and 5 mM guanosine triphosphate–K. The internal solution was adjusted to pH 7.4 by KOH solution. External solution contains the following components: 150 mM NaCl, 5 mM NaH₂PO₄, 10 mM H-Hepes, and 10 mM d-glucose, adjusted to pH 7.4 with NaOH solution. Recording electrode’s resistance is 3 to 5 megohms pulled with a micropipette puller. The membrane voltages are recorded with a computer-controlled amplifier (HEKA, Harvard Bioscience, Inc.) in the current-clamp mode. The hBMSCs are seeded on Si films for ~2 hours and illuminated by an 808-nm laser with adjustable power intensity, frequency, and duration controlled by a function generator.