Effects of 32 Days Aboard the ISS on Quadricep Tendon Nanomechanics (Quadricep femoris tendon, RR-1 and Atomic Force Microscopy)

While the adaptations of tendon to internal stimuli have been extensively researched, the impact of environmental factors (such as microgravity) on its structure and function at the nanoscopic scale (i.e., fibril level) remains largely unexplored. The purpose of this study was to determine the effects of 32 days (d) aboard the International Space Station (ISS) on murine tendon collagen fibril morphology and nanomechanics (Young’s Modulus, YM).

Quadriceps tendon samples from 16wk old female C57BL/6J mice aboard NASA Rodent Research-1 underwent chemical processing and mechanical isolation. Subsequently, collagen fibrils (n equals 38) were studied via atomic force microscopy (AFM, JPK NanoWizard 4a) to compare the morphology (diameter, height) and nanomechanics (average YM) between spaceflight (SF) and ground control (GC) mouse tendon samples. The qp-BioAC-CB1 cantilever (spring constant: 0.3 N/m, tip radius: 10µm) was used under quantitative imaging mode (Qi) for all force and morphological measurements.