Electrical field–induced hASC osteogenic response is affected by siRNA knockdown of primary cilia proteins. A–C) Fluorescence images of EFS-stimulated hASCs after negative control siRNA (A), PKD1 siRNA (B), and IFT siRNA knockdown (C). White arrows indicate the immunostained primary cilia observed under fluorescent microscope. D, E) Expression of osteogenic gene markers, Runx2 (D) and BMP-2 (E), in hASCs after knockdown and 4 h of electrical stimulation. hASC-seeded IDEs were stimulated with 1 V/cm electric field at 1 Hz for 4 h/d in ODM culture. RNA was extracted and analyzed at the end of electrical stimulation. mRNA expressions were normalized to negative control siRNA transfected nonstimulated samples. After siRNA knockdown, electrical field–enhanced osteogenic response was significantly diminished. F) Calcium accretion after siRNA knockdown and 7 d of electrical stimulation. Error bars = sem, Student’s t test compared stimulated samples with nonstimulated control samples at each treatments. *P < 0.05.