In the National Aeronautics and Space Administration’s (NASA’s) biomedical and countermeasure research budget in FY 1999, about $1.7 million was allocated for grants in the NRA program for studies of bone physiology. An additional $959,000 for bone research was funded through the National Space Biomedical Research Institute (NSBRI) (see Table 3.1). More than a dozen projects in the bone program are being conducted or have been completed recently in laboratories at the Ames Research Center (ARC) and Johnson Space Center (JSC), in four university-based laboratories funded through NSBRI, and in several other university laboratories through extramural grants. Studies range in scope from fundamental cellular biology of bone cells, to biomechanics, to the use of modern technology to assess bone status, to intervention research that could be incorporated into countermeasure programs.

Studies at NASA centers and within NSBRI are aimed at understanding the skeletal response to mechanical loading and its deprivation and the development of countermeasures to ameliorate space-flight-related bone loss. The more basic of these projects are carried out at ARC and NSBRI, whereas interventional research is done at ARC, JSC, and NSBRI. A few service functions of the bone program related to NASA missions are handled exclusively at JSC.

Basic Research

Several basic research initiatives are under way. A system has been developed to study the effects of well-standardized, quantifiable loads applied to cultured bone cells. A program has been initiated to evaluate the histomorphometric and other characteristics of bone loss in hindlimb-unloaded rats. In addition, the assessment of a clinical trial of a combined intervention with exercise loading and a potent bisphosphonate should provide complementarity to ongoing bed rest studies in humans.

Basic programs located at ARC constitute a major component of the overall bone program that should provide valuable information bearing directly on problems identified in the Strategy report as being of high priority. These programs include studies of musculoskeletal biomechanics as well as of fundamental bone cell biology. Current projects in bone biology involve the use of contemporary molecular biological techniques to assess the effects of mechanical loads on osteoblastic cells of varying maturity and phenotype. Recently initiated studies involve the application of mechanical loads with complete control and characterization of cycle number, rate, peak intensity, and rate of strain, in order to document changes in osteoblast regulatory genes and gene products.

In accord with Strategy report recommendations, one of the NSBRI programs explores the effects of a variety of pharmacologic agonists known to interact with the estradiol, vitamin D, or calcium-sensing receptors on mature bone cells and their precursors. Another addresses the effects of unloading on bone

TABLE 3.1 Summary of FY 1999 Funding for Bone Physiology







Total ($ thousands)

No. of Projects

Total ($ thousands)

No. of Projects

Molecular and cellular















aThis number may include projects that were still active but were no longer receiving funding in 1999.

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