ASGSB 1998 Annual Meeting Abstracts

[79]
EXPERIMENTAL DESIGN AND PRELIMINARY RESULTS OF A STUDY OF BONE CELLS SUBJECTED TO HYPERGRAVITY.  W.J. Landis, M.A. Kacena*, and K.J. Hodgens. Department of Orthopedic Surgery, Children’s Hospital and Harvard Medical School, Boston, MA 02115 and *Department of Aerospace Engineering, University of Colorado/Bioserve Space Technologies, Boulder, CO 80309

To support a more complete understanding of the potential effects of hypergravity on bone growth and development, a set of experiments has been designed utilizing calvarial osteoblasts obtained from normal 17-day old embryonic chicks and subjected to high gravitational (G) forces at the Hypergravity Facility for Cell Culture (HyFaCC) at NASA/Ames Research Center, Moffett Field, CA. Cellmax Quad modules (Cellco, Inc., Germantown, MD) containing 4 bioreactor cartridges, each inoculated with 7x10⁶ cells growing in DME supplemented with 10% FBS, 12.5 µg/ml ascorbate and 10 mM -glycerophosphate, were placed in an incubator (37 C, 5% CO₂) mounted at the end of a 9 ft centrifuge arm at the HyFaCC. Cartridges were exposed for 2 wks to either 3.3 G or 4.0 G on centrifugation with sampling and medium changes occurring (~1 hr duration) every 2 days. A Quad module prepared and treated identically was maintained at normal gravity (1.0 G) as a control. Centrifuged and control cells are being analyzed in terms of their metabolism of glucose and lactate; type I collagen, osteocalcin, and osteopontin gene expression; and cellular and extracellular matrix ultrastructure.

Results from the first cartridges examined indicated that, over the 2 wk experimental period, glucose levels of control cells decreased from ~90 to ~20 mg/dL and lactate levels increased from ~1.8 to ~8.0 mmol/L (n=3 cartridges); centrifuged cells followed the same trends for both glucose and lactate as those in controls, but measurements were more variable (total of n=6). Scanning electron microscopy showed numerous cells and extensive development of matrix in centrifuged (4.0 G) samples, qualitatively comparable to the cells and matrix observed in controls. These initial data do not yet permit unequivocal conclusions regarding possible effects of hypergravity on osteoblasts and more comprehensive analyses are continuing in this study.

This work was supported by NASA grant NAG5-4377.

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