Placenta-Expanded Stromal Cell Therapy in a Rodent Model of Simulated Weightlessness.

Area of Science:

• Spaceflight physiology
• Regenerative medicine
• Immunology

Background:

• Long-duration spaceflight presents significant health risks to astronauts.
• Limited medical intervention capabilities during missions necessitate reliable therapeutics.
• Human placenta-derived stromal cells (PLX-PAD) are being explored as a potential therapeutic option.

Purpose of the Study:

• To evaluate the therapeutic efficacy of PLX-PAD in mitigating spaceflight-induced physiological decrements.
• To assess the impact of PLX-PAD on immune function, central nervous system changes, and musculoskeletal health during simulated weightlessness.

Main Methods:

• Adult female mice were subjected to hindlimb unloading (HU) for 30 days to simulate weightlessness.
• PLX-PAD treatment was administered near the onset of HU.
• Evaluated outcomes included thymic atrophy, immune cell percentages, cytokine expression in the hippocampus, and bone and muscle structure.

Main Results:

• PLX-PAD treatment was well-tolerated and partially mitigated HU-induced thymic atrophy and altered neutrophil percentages.
• PLX-PAD did not rescue HU-induced changes in lymphocytes, monocytes, NK cells, T-cells, or splenic atrophy.
• Partial mitigation of HU effects on hippocampal cytokine expression was observed, but bone and muscle remained unprotected.

Conclusions:

• PLX-PAD demonstrates therapeutic potential for specific physiological deficits encountered during simulated spaceflight, particularly immune and CNS effects.
• The distinct responses of immune/CNS versus bone/muscle suggest different regulatory mechanisms for these tissues.
• Comprehensive protection against spaceflight's deleterious effects will likely require a combination of therapeutic strategies.