Cell cultures were maintained in the cell culture module (CCM) at 37 degrees Celsius , the permissive temperature for SV40 large T-antigen in the FOB cell line. Fractions of culture media were collected on days 1, 4, 8, and 12 from both flight and ground cultures, and were analyzed for glucose content to measure glucose metabolism. At the appropriate time following recovery of the spacecraft, RNA was isolated from the FOB cultures and quantitated by UV spectrophotometry for Northern or RNase protection assays. Osteonectin, alkaline phosphates, and type I collagen were quantified with Northern Analysis. Cytosine gene expression was measured by RNase protection assay. The levels of carboxyterminal propertied of type I pro collagen (PCP) were measured by radioimmunoassay in order to evaluate matrix production rates. Prostaglandin E2 (PGE2) levels were measured by enzyme immunoassay. The morphology of the cell cultures was also examined using electron microscopy.

Results:

Both flight and ground controls utilized glucose at a steady and nearly identical rate. High levels of collagen accumulation were detected in flight and ground cultures from flight day 4 increasing steadily to day 12 and stabilizing after day 12, suggesting a decrease in the rate of collagen synthesis, or increase in collagen breakdown occurring between day 12 and landing. The rates of collagen accumulation in flight and control cells were indistinguishable, consistent with similar rates of collagenous matrix production. No significant difference in PGE2 levels were detected between flight and ground cultures. The steady state level of osteonectin mRNA decreased dramatically, while alkaline phosphatase and collagen mRNA decreased slight from baseline. There was a trend toward lower levels of osteonectin (p<.06) and collagen (p<.09) mRNA in flight cultures. The level of TGF-beta2 (~30%) and TGF-beta1 mRNA (~20) decreased slight in flight cells compared to ground controls. Scanning electron microscopy demonstrated no qualitative morphological differences between flight and ground controls.