During spaceflight, many astronauts experience moderate to severe lumbar pain, which
might originate from intervertebral disc (IVD) swelling triggered by the lack of
compressive loads in microgravity. IVD swelling alters nutrition diffusion in the largely
avascular IVD, thereby affecting cell activity. However, to date, it is still unclear how
unloading due to microgravity affects IVD multiphysics and consequent protein turnover.
To shed light on this topic, a multiscale approach was used. Finite ...
During spaceflight, many astronauts experience moderate to severe lumbar pain, which
might originate from intervertebral disc (IVD) swelling triggered by the lack of
compressive loads in microgravity. IVD swelling alters nutrition diffusion in the largely
avascular IVD, thereby affecting cell activity. However, to date, it is still unclear how
unloading due to microgravity affects IVD multiphysics and consequent protein turnover.
To shed light on this topic, a multiscale approach was used. Finite Element (FE)
simulations with an L4-L5 mechanotransport IVD model simulated mechanically coupled
nutrient diffusion in a normal gravitational environment and during five days and six
months of space flight. Mechanotransport simulations provided local changes in pressure
and nutrient concentrations within the IVD. Such information was subsequently used to
feed an Agent-Based (AB) model that simulated a 1mm3
volume of 4000 cells in the
central tissue of the IVD: the Nucleus Pulposus. The AB model allowed to assess the cell
activity regarding tissue structural protein and protease mRNA expressions.
Results suggest that astronaut’s IVD reach a stable prolonged swelling phase early on in
the adaptation process to space, which leads to a series of biomechanical reactions that
indicate signs of disc degeneration.
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