TABLE III.
Summary of studies demonstrating modulation of cell migration through acoustic mechanostimuli.
| Cell | Frequency | Intensity | Exposure time | Summary |
|---|---|---|---|---|
| Immortalized mouse olfactory ensheathing cells (OECs)253 | 20, 60, and 80 Hz | 2.173g | “Long durations” (not specified; 6, 12, and 24 h in prior study) | 60 Hz stimulation produced larger spheroids (70-fold), indicating better migration |
| Human lung fibroblasts (LL24), Mouse fibroblasts (L929)139 | 100 Hz–1.6 kHz | 0.2 W | 5 min | Observation over 4 h showed frequency-dependent improvement in cell migration and migration distance; both cells showed increased migration (approximately 10%) at 100 Hz, although this decreased unsteadily with increasing frequency |
| Mouse fibroblasts (L929)247 | 11.2 kHz | 2, 4 V | 24 h | Vibration in the orthogonal direction to the gap of the scratch in the wound healing assay: twofold increase in migration with 2 V vibration but decrease in vibration at 4 V; vibration parallel to the gap: both 2 and 4 V vibration led to reduced migration rate |
| Bovine aortic smooth muscle cell (SMC)246 | 20 kHz | 1.5 W | 15 s | Observations at 0.2, 2, and 24 h post-exposure incubation showed 2.4-fold decrease in migration after sonication immediately following stimulation; this recovered slowly with post-exposure incubation but still remained at levels below that of untreated cells |
| Odontoblast-like cells (MDPC-23)248 | 45 kHz | 25 mW/cm2 | 30 min | Cell proliferation and rate of wound healing significantly reduced in the presence of cell proliferation inhibitor mitomycin C (MMC), although not fully quelled; no effect on cell migration |
| Mouse calvarial derived osteoblasts (MC3T3-E1)249 | 45 kHz (continuous), 1 MHz (pulsed) | 25 mW/cm2 (45 kHz), 250 mW/cm2 (1 MHz) | 30 min | Both frequencies promoted migration in the presence of MMC (which has no significant effect of migration), although MHz stimulation displayed greater increase |
| Human epidermal keratinocyte cells (HaCaT)252 | 0.5 MHz | 0.3 MPa | 1 min | Migration improved by approximately 50% |
| Immortalized human chondrocytes (C-28/I2)254 | 1 MHz | 30 mW/cm2 | 24, 48, and 72 h | Increased migration rate with or without the presence of cytokines (IL-1b) |
| Mouse calvarial derived osteoblasts (MC3T3-E1), Mouse osteosarcoma cells (LM8), Human osteosarcoma cells (SaOs-2), Human renal cancer cells (786-O), Human prostate cancer cells (PC-3), Human lung cancer cells (A549)255 | 1.5 MHz | 30 mW/cm2 | 20 min/day for 3 days | Migration of MC3T3-E1 increased by 8.7% and 9.4% at 6 and 12 h, respectively, whereas the other cells were unaffected |
| Human periodontal ligament stem cells (PDLSC)256 | 1.5 MHz | 30, 60, and 90 mW/cm2 | 30 min | Migration rate improved after 24 h post-exposure incubation |
| Normal human urothelial cells (NHU)257 | 1.5 MHz | 30 mW/cm2 | 20 min/day for 2 days | No effect on migration |
| Rat bone marrow derived stem cells258 | 3 MHz | 20, 30, 40, and 50 mW/cm2 | 20 min/day for 10 days | Increased migration rate, particularly at 50 mW/cm2 |
| Mouse embryonic fibroblasts (NIH-3T3)230 | 14 MHz | 59.3 mW cm2 | 4–8 h | Migration speed increased by 42% after 4 h post-exposure incubation although significant retraction of cells observed at higher intensities |
| Madin–Darby canine kidney cells (MDCK-II)201 | 100 MHz | 80 mW cm2 | 27 h | Increased migration rate by 135% in addition to a significant increase in the rate of cell growth |
| Human osteosarcoma cells (SaOs-2)240 | 159 MHz | 2–4 mW | 48 h | Migration rate increased as a function of intensity with no preference in direction |