Growth arrest-specific 6 rejuvenates senescent HUCMSCs through upregulating Nrf2 for diabetic wound therapy

Diabetic foot ulcers, ranked as the most severe complications of diabetes, frequently demonstrate a limited response to conventional treatment modalities. Mesenchymal stem cells (MSCs) constitute a prospective regenerative strategy for diabetic wound healing. However, MSCs expanded ex vivo exhibit vulnerability to proliferative aging, thus limiting translational utility. Growth arrest-specific 6 (GAS6) is known to play multiple roles in various cell and tissue repair processes. This research delineates GAS6's impact on MSCs senescence and associated intracellular signaling pathways, while assessing its ability to augment aged MSCs regenerative capacity in diabetic wound healing. GAS6 significantly improved the aging phenotype of MSCs, while siGAS6 led to the aging of MSCs. GAS6 regulated the degradation of Keap1 through the p62-dependent autophagy pathway, thereby promoting the nuclear entry of Nrf2 to exert an anti-aging effect. Meanwhile, it was verified that GAS6 regulated Keap1 and Nrf2 by activating the PI3K/Akt pathway, thus delaying the aging of MSCs. The angiogenic capacity of aging MSCs-derived conditioned medium (MSCs-CM) was improved by GAS6 through the upregulation of Nrf2, which was verified at both cellular and animal levels. GAS6 promoted the accumulation of p62 by activating the PI3K/Akt signaling pathway. p62 bound to Keap1, promoted the degradation of Keap1, and competitively inhibited Keap1's binding to Nrf2, thereby reducing the ubiquitination and degradation of Nrf2. Ultimately, Nrf2 accumulated in the cell and translocated to the nucleus, where it bound to antioxidant genes and exerted an effect of delaying the senescence of MSCs. Additionally, GAS6 improved the angiogenic capacity of aging MSCs-CM by upregulating Nrf2.