Vibration stimuli and the differentiation of musculoskeletal progenitor cells: Review of results in vitro and in vivo

Table 1 Summary of effects of low magnitude, high frequency vibration on human cells in vitro

Prè et al[100]	Adipose derived MSCs	30 Hz, 45 min/d, 28 d	Increase in col-I and osteonectin expression in vibrated group on day 14, lost by day 21. Increased mineralisation in vibrated group at 21 d, lost by day 28
Kim et al[102]	MSCs (2 donors)	0.3g, 30 Hz for main study. Applied for 10 min/d, 5 d a week for 21 d	Vibration increased ALP activity (days 7, 14 and 21), mRNA (ALP, osteopontin and VEGF) upregulated at day 7. No changes (bone sialoprotein or osteonectin mRNA). In osteogenic media, LMHFV increased the calcium deposition in cultures
Uzer et al[103]	Adipose derived MSCs	30 and 100 Hz, 0.15, 1 and 2g. 30 min per day for 3-14 d	Cell number increased over 3 d for all conditions. Mineralisation at 14 d increased for 100 Hz and 30 Hz (2g). Prevented cytoskeletal remodelling to negate the effects
Zhang et al[104]	Peridontal ligament stem cells	0.3g (10, 20, 30, 40, 50, 60, 90 and 120, 150 and 180 Hz), 20 min/d to 5 d	LMHFV decreased proliferation, ALP activity highest at 30 Hz. Osteocalcin expression was highest at 40, 50, 60, 90 and 120 Hz. Levels of col-I, RUNX-2 and osterix increased at 40 and 50 Hz
Wolchok et al[105]	laryngeal fibroblasts	100 Hz and 3.4g (1 s vibration followed by 2 s pause), 6 h followed by an 18 h rest for 21 d	Enhanced secretion of TGFB-1, fibronectin, collagen, increased construct stiffness. Increased gene expression of range of matrix molecules
Cho et al[106]	Umbilical cord stem cells	10, 20, 30 and 40 Hz, continuous for 5 d	Increased mRNA and protein levels (MAP2, NF-L and NeuroD1). Time dependant increases in O4 and ERK (12 h at 40 Hz)
Choi et al[107]	Adipose derived MSCs	10, 20, 30 and 40 Hz, continuous for 4 d	30 Hz increased astrocyte, oligodendrocyte and neuronal markers, inhibited adipogenesis. Increasing frequency reduced cell proliferation. Time dependant changes in ERK phosphorylation
Edwards and Reilly[101]	hES-MP 002.5 cells	0.3g and 15, 30, 45, 60 Hz, one bout 4 min	Increased ALP activity at 60 Hz 48 h post vibration

LMHFV: Low magnitude, high frequency vibration; VEGF: Vascular endothelial growth factor; ALP: Alkaline phosphatase; ERK: Extracellular regulated protein kinases.