TABLE II.
Summary of studies demonstrating modulation of cell proliferation through acoustic mechanostimuli.
| Cell | Frequency | Intensity | Exposure time | Summary |
|---|---|---|---|---|
| Fibroblasts232 | 45 kHz | 15 and 50 mW/cm2 | 5 min | 30% and 43% increase in DNA content within 18 h of post-exposure incubation, as an indicator of the increase in cell proliferation |
| Osteoblasts232 | 45 kHz | 5 and 30 mW/cm2 | 5 min | 32% and 35% increase in DNA content within 18 h of post-exposure incubation, as an indicator of the increase in cell proliferation |
| Human amnion-derived mesenchymal stem cells (hAD-MSC)94 | 250 kHz | 30 mW/cm2 | 30 min/day for a day | Increase in DNA content, as an indicator of increased cell proliferation |
| Mouse myoblasts (C2C12)228 | 0.5, 1, 3, 5 MHz | 250–1000 mW/cm2 | 24 h | Improved proliferation |
| Bovine aortic endothelial cells229 | 0.5, 1, 3.5, and 5 MHz | 1.2 W/cm2 | 5, 15, and 30 min/day for 3 days | Improved proliferation was detected within 24 h of post-exposure incubation although the proliferation rate was dependent on intensity |
| Human cardiac microvascular endothelial cells (hcMEC)227 | 0.51, 0.994, and 4.36 MHz | 3, 25, 50, and 600 W/cm2 | 10 min (low intensity), 20 min (high intensity) | Enhanced proliferation at all frequencies irrespective of intensity |
| Fibroblasts232 | 1 MHz | 0.7 and 1.0 W/cm2 | 5 min | 47% and 37% increase in DNA content within 18 h of post-exposure incubation, as an indicator of the increase in cell proliferation |
| Osteoblasts232 | 1 MHz | 0.7 and 1.0 W/cm2 | 5 min | 34% and 52% increase in DNA content within 18 h of post-exposure incubation, as an indicator of the increase in cell proliferation |
| Rat Schwann cells234 | 1 MHz | 27.25 W/cm2 | 10 min/day for 5 days | Improved proliferation |
| Rat pheochromocytoma cells (PC-12)235 | 1.48 MHz | 0.1 MPa | 5, 10, 20, and 30 min/day for 3 days | 138%–166% increase in proliferation |
| Human nucleus pulposus cells (HNPSV-1)236 | 1.5 MHz | 7.5, 15, 30, 60, and 120 mW/cm2 | 20 min/day for 5 or 12 days | Improved cell proliferation |
| Human bone marrow derived mesenchymal stem cells (hBMD-MSC)233 | 1.5 MHz | 30, 40, 50, 60, and 80 mW/cm2 | 5–20 min/day for 4 days | Increase in proliferation with 50 and 60 mW/cm2 with at least 5 min incubation per day |
| Mouse myoblasts (C2C12)237 | 1.5 MHz | 30 mW/cm2 | 20 min/day for 8 days | Increased proliferation rate and cell number |
| Primary skin fibroblasts168 | 1.5 MHz | 30 mW/cm2 | 6–11 min/day for 7 days | Improved proliferation with 11 min stimulation |
| Rabbit knee synovial membrane cells (HIG-82)238 | 3 MHz | 30 mW/cm2 | 15 min | No effect on cell proliferation |
| Mouse neuroblastoma cells (Neuro2A), Human colon adenocarcinoma cells (HT29)227 | 0.51, 0.994, and 4.36 MHz | 3, 25, 50, and 600 W/cm2 | 10 min (low intensity), 20 min (high intensity) | Positive response to 4.36 MHz, 600 W/cm2 but decreased proliferation at 50 W/cm2; in both cell lines, the proliferation rate decreased after 120 h |
| Madin–Darby canine kidney epithelial cells (MDCK)227 | 0.51, 0.994, and 4.36 MHz | 3, 25, and 50 W/cm2 | 10 min (low intensity), 20 min (high intensity) | Unresponsive to 4.36 MHz, 50 W/cm2 but improved proliferation rate at 4.36 MHz, 25 W/cm2; highest proliferation rate at 3 W/cm2 |
| Human mesenchymal stem cells (hMSC)184 | 5 MHz | 20 mW/cm2 | 5 min/day for 14 days | Increase in proliferation |
| Human monocytes cell line (U-937)239 | 48.8 MHz | 467 mW | 48 h | 36% increase in cell proliferation |
| Madin–Darby canine kidney cells (MDCK-II), Human osteosarcoma sarcoma osteogenic cells (SaOs-2), human embryonic kidney cells (T-REx-293), Human monocytic tumor cells (U-937)201 | 100 MHz | 80 mW/cm2 | 5 min–27 h | Increase in cell proliferation |
| Human osteosarcoma cells (SaOs-2)240 | 159 MHz | 300 mW/cm2 | 5 h | Increase in proliferation |