Histomorphometric and electron microscopic analyses of tibial epiphyseal plates from Cosmos 1887 rats

Abstract

Previous studies have shown that the changes seen in the bones of growing rats exposed to microgravity are due in part to changes that occur in the growth plate during spaceflight. In this study, growth plates of rats flown aboard Cosmos 1887 (12.5-day flight plus 53.5-h recovery at 1 g) were analyzed using light and electron microscopy and computerized planimetry. The proliferative zone of flight animals was found to be significantly (P less than or equal to 0.01) larger than that of controls, while the reserve and hypertrophic/calcification zones were significantly reduced. Flight animals also had more cells per column in the proliferative zone than did controls and less in the hypertrophic/calcification region. The total number of cells, however, was significantly greater in flight animals. No difference was found in perimeter or in shape factor, but area was significantly less in flight animals. Electron microscopy showed that collagen fibrils in flight animals were wider than in controls. Since the time required for a cell to cycle through the growth plate is 2-3 days at 1 g, the results reported here represent both the effects of exposure to microgravity and the initial stages of recovery from that exposure.

Tissue engineering of cartilage in space

“…4 A and B), but the average collagen fiber diameter was similar in the two groups (22 Ϯ 2 nm) and comparable to that previously reported for developing articular cartilage (23). Randomly oriented collagen in Mir samples would be consistent with previous reports that microgravity disrupts fibrillogenesis (24,25).…”

Integrating with integrins.

“…Examples include the effects of gravity on bone (Carter et al, 1989;Duke et al, 1990), tension on muscle (Vandenburgh et al, 1991), and hemodynamic forces on blood vessels (Davies and Tripathi, 1993 (Ingber, 1991). This conversion of mechanical force into a chemical signal requires a transducer that fulfills two basic criteria: 1) it must physically interconnect with the cytoskeleton to sense stresses and strains, and 2) it must regulate biochemical signaling events.…”

Effects of fluid-induced shear stress on articular cartilage regeneration under simulated aspects of microgravity

“…Collagen fibrils were determined to be wider than ground based controls while proteoglycans were found to be larger and more numerous (Duke et al, 1990). No significant alteration in the extracellular matrix organization was detected in rats aboard…”

“…"pure lg conditions", M0). Unfortunately, to compare this finding with tissue cellularity of spaceflown animal experiments is difficult since in vivo studies have not provided consistent results (Duke et al, 1985;Duke et al, 1990;Montufar-Solis et al, 1992). Articular cartilage regenerated aboard space station MIR for 4 months had similar cell viability and cell numbers as that grown on Earth (Freed et al, 1997b).…”

“…Additionally, while specific results have been inconsistent, in vivo studies reveal abnormalities of proteoglycan patterns, sizes, and distributions in the growth plates of spaceflown rats (Duke et al, 1985;Duke et al, 1990).…”