Extracellular matrix mechanical cues (dys)regulate metabolic redox homeostasis due to impaired autophagic flux.

Background: Extracellular matrix (ECM) stiffness is increasingly recognized as a critical regulator of cellular behaviour, governing processes such as proliferation, differentiation, and metabolism. Neurodegenerative diseases are characterized by mitochondrial dysfunction, oxidative stress, impaired autophagy, and progressive softening of the brain tissue, yet research into how mechanical cues influence cellular metabolism in this context remains scarce.

Materials and methods: In this study, we evaluated the long-term effects of brain-compliant, soft ECM on mitochondrial bioenergetics, redox balance, and autophagic capacity in human neuroblastoma (SH-SY5Y) and mouse hippocampal (HT22) cell lines, as well as primary mouse neurons.

Results: We observed that prolonged exposure to soft ECM does not impact cell proliferative capacity of neuronal cells but results in mitochondrial bioenergetic dysfunction, redox imbalance, and disrupted autophagic flux. These findings were consistently validated across both human and mouse neuronal cells. Our data indicate a decreased maximal autophagic capacity in cells exposed to long-term soft ECM, potentially due to an imbalance in autophagosome formation and degradation, as demonstrated by decreased LC3 II levels following chloroquine-induced autophagic flux inhibition. This impairment in autophagy was coupled with increased cellular oxidative stress, further indicating metabolic alterations.

Conclusions: These findings emphasize the critical role of ECM stiffness in regulating neuronal cell metabolism and suggest that prolonged exposure to soft ECM may mimic key aspects of neurodegenerative disease pathology, thereby enhancing the physiological relevance of in vitro models. This study underscores the necessity for further research into ECM mechanics as a contributing factor in neurodegenerative disease progression and as a potential target for therapeutic strategies.