• RPM device settings are crucial in providing adequate microgravity simulation • Microgravity and hypoxia can induce similar effects on MG-63 cells • Simulated microgravity changed the expression profile of MG-63 cells • The bone tissue model showed signs of deterioration in simulated microgravity Bone degeneration remains a significant concern for long-term space missions due to microgravity-induced reductions in bone density and imbalances in bone remodeling processes. Discrepancies between spaceflight and ground-based analog studies complicate our understanding of the problem, particularly given the limitations of in vitro models that lack tissue-like environments. Research on osteoblast differentiation –crucial for bone maintenance – has yielded conflicting results, depending on the model and culture conditions. This study aims to establish a simple, scaffold-based bone tissue model using MG-63 cells cultured on poly(L-lactide- co -glycolide) (PLGA) scaffolds under simulated microgravity in random positioning machine (RPM), enabling further investigation into bone deconditioning mechanisms. After 14 days of culture, MG-63 cells exhibited osteogenic differentiation on both control flat glass substrate and PLGA scaffolds, with some variations between them, suggesting different maturation stages. Enclosure conditions in the vials, without contact with CO 2 standard cell culture atmosphere, impaired cell differentiation, suggesting hypoxia-induced effects. Compared to the static standard cell culture counterparts, simulated microgravity tended to cause a decrease in expression of some osteogenic markers, such as runt-related gene 2 (Runx2) and type I collagen, and an increase in others, such as alkaline phosphatase (ALP). The use of scaffolds may modulate the effects of simulated microgravity. This simple bone tissue model shows potential for simulating microgravity-induced bone changes and could support research in Earth-based analog environments if proven in real microgravity.
Szaflarska et al. (Wed,) studied this question.