Table 2.
Tensile strain (osteogenic differentiation)
| Authors | Tensile Strain | Pattern | Cell Type | Outcome |
|---|---|---|---|---|
| Huang et al.90 | 3%, 0.1 Hz for 1, 3 or 5 days | Cyclic | hMSCs | Reduced proliferation. Increased FAK phosphorylation. Reorientation of cytoskeleton. Increased cbfa1 (P < 0.05), ALP (P < 0.05) and mineralized matrix deposition (P < 0.05). Fibronectin and laminin coatings enhanced differentiation. |
| Ward et al.96 | 3%–5%, 0.5 Hz, 2 h·d−1, 28 days | Intermittent | hMSCs | Increased BSP2, OCN, Osterix and mineral deposition. |
| Jagodzinski et al.88 | 2% or 8%, 2 h per 3 times a day, 3 days. 1, 4 and 7 days | Cyclic | hMSCs |
2%: increased OCN at 4 days, decreased by Day 7. 8%: increased ALP (P < 0.04), OCN (P < 0.01) and cbfa1 (P < 0.03). Overall effect augmented at 8% stretch. |
| Haasper et al.234 | 2% or 8%, 1 Hz. 3 times daily for 2 h over 3 days | Cyclic | hMSCs | Increased FosB, RUNX2 (P < 0.05). Col-I expression increased with length of treatment (P < 0.05). Greater response at 8%. |
| Shi et al.235 | 3%, 6% or 9%, 0.5 Hz for 1, 3, 7 and 10 days | Uniaxial, cyclic, sinusoidal | hMSCs | Decreased ALP (P < 0.05). Largest decrease in 3% group. Decreased RUNX2 and OPN (P < 0.05) gene expression but not protein level. Col-I decreased by Day 7. |
| Zhang et al.236 | 10%, 1 Hz for 96 h | Continuous sinusoidal | Rat BMSCs | Reduced proliferation. Increased RUNX2, ALP, Col I and OCN (all P < 0.05). |
| Sumanasinghe et al.91 | 0, 10% or 12%, 1 Hz, 4 h·d−1, 7 or 14 days. Cultured in 3D collagen matrices | Uniaxial, cyclic | hMSCs | BMP-2 expression increased at 10% and 12% at 7 and 14 days (P < 0.05). Increased BMP-2 in 12% group at 14 days only (P < 0.05). |
| Koike et al.95 | 0.8%, 5%, 10%, 15%, 24 and 48 h at 1 Hz | Equibiaxial | ST-2 murine MSC cell line | Proliferation increased at 5%, 10% and 15% (P < 0.05). ALP and RUNX2 increased at 0.8% and 5% (P < 0.05) but decreased at 10% and 15% (P < 0.001). Cbfa1/RUNX2 increased at lower magnitudes (0.8% and 5%) and decreased at the higher 15% elongation (P < 0.05). OCN decreased at 5%, 10% and 15%. Overall, osteoblastic differentiation increased at low magnitudes. |
| Wu et al.237 | 0, 3%, 8%, 13% and 18%, 0.5 Hz for 8 h·d−1 for 3 days | Cyclic | Murine MSCs | 8% strain optimal. Increased ALP and matrix mineralization (P < 0.01). Increased BMP-2, RUNX2 (P < 0.01). |
| Qi et al.89 | 2 000 με for 40 mins | Cyclic | Rat MSCs | Increased ALP and cbfa1 (P < 0.05) |
Studies are presented in increasing order of strain and according to cell type
hMSCs human mesenchymal stem cells, Col-1 collagen-1, OCN osteocalcin, ALP alkaline phosphatase, RUNX 2 runt-related transcription Factor 2, cbfa1 core binding factor alpha 1, FAK focal adhesion kinase, OPN osteopontin, cpm cycles per minute, TGF-β transforming growth factor-1, BGH3 TGF-β1-induced protein ig-h3, BMP2 bone morphogenetic protein-2