ASGSB 1998 Annual Meeting Abstracts

[72]
TEMPERATURE INCREASE MAY MEDIATE VIBRATION STIMULATION OF COLLAGEN GEL CONTRACTION BY RAT TENDON FIBROBLASTS AND BONE FORMING CELLS.   B. Johnson-Wint¹ and M. Cobb². ¹Biological Sciences, Northern Illinois University, DeKalb, ¹Life Sciences, NASA Ames Research Center, ²Lockheed Martin Engineering and Sciences Company, Moffett Field, CA

Collagen Type I is a major load bearing structural component of both bone and tendon, and muscle is attached to bone by tendon. Coordination of muscle strength and the collagen I based structural strength of tendons and bones in response to load is essential for musculoskeletal development and function. We investigated the possibility that muscle vibration influ-ences the collagen I packing and strength of attached tendon and bone.

Foot tendon fibroblasts and metatarsal osteoblasts/osteocytes from young adult rats were grown for 4-6 passages in culture and assayed for their ability to organize collagen I fibers in a contracting collagen gel assay. Cell embedded floating Type I collagen gels were cultured stationary, with vibration or at different temperatures. A vibrating table was used to deliver known vibration frequencies and amplitudes to the cultures. Cell mediated physical remodeling of the collagen fibers in the gel (contraction) was followed by measuring the area of the collagen gel at appropriate time intervals.

Both cell types contracted collagen up to 30% faster than controls over the frequency range 8.5-65 Hz. At 82-97 Hz the difference in contraction rate from controls was minimal. Collagen contraction at 35-45 Hz increased with amplitude from no effect at 0.95 m/s² (0.09 g) to maximum increase over controls at 1.81 m/s² (0.18 g). The temperature of culture medium vibrated at 35-45 Hz increased linearly with amplitude from no change at 0.74 m/s² (0.07 g) to 3 C elevation of temperature at 2.25 m/s² (0.23 g). The direct effect of temperature alone on collagen contraction by these cells was examined over the temperature range of 33 -41 C (37 ±4 C) and was found to increase above and decrease below 37 C. These results demonstrate that tendon fibroblasts and osteoblasts/osteocytes are sensitive to certain frequency/amplitude vibration in their organization of collagen and that part of the vibration effect may be due to elevated temperature.

(Supported by NASA: ¹NASA-ASEE-Stanford Summer Faculty Fellowship Program.)

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