Objective To investigate the effect of hydrostatic pressure and insulin-like growth factor 1 (IGF-1) on the expression of filamentous actin (F-actin) of temporomandibular joint disc cells in goats, and to analyze the F-actin changes of temporomandibular joint disc cells in vitro under hydrostatic pressure and IGF-1 stimulation. Methods The bilateral temporomandibular joint discs were harvested from 4 1-month-old goats, and temporomandibular joint disc cells were isolated with collagenase. Immunohistochemical staining for collagen type I and collagen type II was performed for identification. The cells at passages 2-3 were used; the experiment was divided into 4 groups according to different interventions: the cells were cultivated with complete medium in group A as control; the cells were intervened by hydrostatic pressure (0.2 MPa and 1 Hz for 3 hours) in group B, by complete medium containing IGF-1 (10 ng/mL) in group C, and by a combination of hydrostatic pressure (0.2 MPa and 1 Hz for 3 hours) and complete medium containing IGF-1 (10 ng/mL) in group D. The changes of F-actin at 24 and 72 hours after cultivation were observed by immunofluorescence staining. The cell fluorescence intensity was measured. Results The cultivated cells were identified to be temporomandibular joint disc cells by morphological observation and immunohistochemical staining. At 24 hours, fluorescence intensity of groups A and C was b and clear, with normal morphology of temporomandibular joint disc cells; F-actin arranged in disorder in group B, and F-actin was thinner with arrangement disorder in group D. At 72 hours, the F-actin arranged regularly in groups A and C; however, some F-actin became blurry with irregular arrangement, breakage, and pseudopodia in group B; and F-actin was thinner and ruptured formed in group D. With time passing, the fluorescence intensity of F-actin in groups A, B, and D had an increasing trend, showing significant differences between 24 hours and 72 hours (P lt; 0.05); but there was no significant difference between 24 and 72 hours in group C (t=0.284, P=0.781). At 24 hours, fluorescence intensity of F-actin was highest in group C and was lowest in group B, showing significant difference when compared with groups A and D (P lt; 0.05). At 72 hours, fluorescence intensity in groups B and D was significantly lower than that in groups A and C (P lt; 0.05), but there was no significant difference between groups B and D, and between groups A and C (P gt; 0.05). Conclusion Hydrostatic pressure may cause the F-actin breakage and rearrangement of temporomandibular joint disc cells, and IGF-1 can up-regulate the F-actin expression. Such effects may be correlated with the biological behavior of the temporomandibular joint disc cells.
Objective To review the recent research progress of the bioreactor biophysical factors in cartilage tissue engineering. Methods The related literature concerning the biophysical factors of bioreactor in cartilage tissue engineering was reviewed, analyzed, and summarized. Results Oxygen concentration, hydrostatic pressure, compressive force, and shear load in the bioreactor system have no unified standard parameters. Hydrostatic pressure and shear load have been in controversy, which restricts the application of bioreactors. Conclusion The biophysical factors of broreactor in cartilage tissue engineering have to be studied deeply.
Objective To explore the effect of hydrostatic pressure on intracellular free calcium concentration ([Ca2+]i) and the gene expression of transient receptor potential vanilloid (TRPV) in cultured human bladder smooth muscle cells (hb-SMCs), and to prel iminarily probe into the possible molecular mechanism of hb-SMCs prol iferation stimulated by hydrostatic pressure. Methods The passage 6-7 hb-SMCs were loaded with Ca2+ indicator Fluo-3/AM. When the hb-SMCs were under 0 cm H2O (1 cm H2O=0.098 kPa) (group A) or 200 cm H2O hydrostatic pressure for 30 minutes (group B) and then removing the 200 cm H2O hydrostatic pressure (group C), the [Ca2+]i was measured respectively by inverted laser anningconfocal microscope. When the hb-SMCs were given the 200 cm H2O hydrostatic pressure for 0 hour, 2 hours, 6 hours, 2 hours, and 24 hours, the mRNA expressions of TRPV1, TRPV2, and TRPV4 were detected by RT-PCR technique. Results The [Ca2+]i of group A, group B, and group C were (100.808 ± 1.724), (122.008 ± 1.575), and (99.918 ± 0.887) U, respectively; group B was significantly higher than groups A and C (P lt; 0.001). The [Ca2+]i of group C decreased to the base l ine level of group A after removing the pressure (t=0.919, P=0.394). The TRPV1, TRPV2, and TRPV4 genes expressed in hb-SMCs under 200 cm H2O hydrostatic pressure at 0 hour, 2 hours, 6 hours, 12 hours, and 24 hours, but the expressions had no obvious changes with time. There was no significant difference in the expressions of TRPV1, TRPV2, and TRPV4 among 3 groups (P gt; 0.05). Conclusion The [Ca2+]i of hb-SMCs increases significantly under high hydrostatic pressure. As possible genes in stretch-activated cation channel, the TRPV1, TRPV2, and TRPV4 express in hb-SMCs under 200 cm H2O hydrostatic pressure. It is possible that the mechanical pressure regulates the [Ca2+]i of hb-SMCs by opening the stretch-activated cation channel rather than up-regulating its expression.