Kulesh D A, Anderson L H, Wilson B, Otis E J, Elgin D M, Barker M J, Mehm W J, Kearney G P
Division of Altitude and Hyperbaric Physiology, Armed Forces Institute of Pathology, Washington, District of Columbia 20306.
J Cell Biochem. 1994 Aug;55(4):530-44. doi: 10.1002/jcb.240550412.
Myoblast cell cultures have been widely employed in conventional (1g) studies of biological processes because characteristics of intact muscle can be readily observed in these cultured cells. We decided to investigate the effects of spaceflight on muscle by utilizing a well characterized myoblast cell line (L8 rat myoblasts) as cultured in the recently designed Space Tissue Loss Flight Module "A" (STL-A). The STL-A is a "state of the art," compact, fully contained, automated cell culture apparatus which replaces a single mid-deck locker on the Space Shuttle. The L8 cells were successfully flown in the STL-A on the Space Shuttle STS-45 mission. Upon return to earth, reculturing of these spaceflown L8 cells (L8SF) resulted in their unexpected failure to fuse and differentiate into myotubes. This inability of the L8SF cells to fuse was found to be a permanent phenotypic alteration. Scanning electron microscopic examination of L8SF cells growing at 1g on fibronectin-coated polypropylene fibers exhibited a strikingly different morphology as compared to control cells. In addition to their failure to fuse into myotubes, L8SF cells also piled up on top of each other. When assayed in fusion-promoting soft agar, L8SF cells gave rise to substantially more and larger colonies than did either preflight (L8AT) or ground control (L8GC) cells. All data to this point indicate that flying L8 rat myoblasts on the Space Shuttle for a duration of 7-10 d at subconfluent densities results in several permanent phenotypic alterations in these cells.
成肌细胞培养物已广泛应用于生物过程的传统（1g）研究中，因为在这些培养细胞中可以很容易地观察到完整肌肉的特征。我们决定通过利用一种特性明确的成肌细胞系（L8大鼠成肌细胞）来研究太空飞行对肌肉的影响，该细胞系在最近设计的太空组织损失飞行模块“A”（STL-A）中进行培养。STL-A是一种“先进的”、紧凑的、完全封闭的自动化细胞培养装置，它取代了航天飞机上的一个中层舱储物柜。L8细胞在航天飞机STS-45任务中成功搭载于STL-A中飞行。返回地球后，对这些太空飞行后的L8细胞（L8SF）进行重新培养，结果发现它们意外地无法融合并分化为肌管。L8SF细胞无法融合被发现是一种永久性的表型改变。与对照细胞相比，在纤连蛋白包被的聚丙烯纤维上以1g条件生长的L8SF细胞的扫描电子显微镜检查显示出明显不同的形态。除了无法融合为肌管外，L8SF细胞还相互堆积。当在促进融合的软琼脂中进行检测时，L8SF细胞产生的菌落比飞行前（L8AT）或地面对照（L8GC）细胞产生的菌落大得多且数量多得多。到目前为止的所有数据表明，在航天飞机上以亚汇合密度将L8大鼠成肌细胞飞行7-10天会导致这些细胞出现几种永久性的表型改变。
