Excessive formation of type 1 diabetes-derived NETs impairs osteogenic differentiation of BMSCs through ERK1/2 hyperactivation and TSPAN11 downregulation

Bone regeneration is impaired in type 1 diabetes mellitus (T1D), but the underlying mechanisms remain incompletely understood. Neutrophil extracellular traps (NETs) are implicated in diabetic complications, yet their effects on bone marrow mesenchymal stem cell (BMSCs) osteogenesis are unclear. Single-cell RNA sequencing was used to characterize BMSCs alterations in healthy and T1D mice. NETs accumulation and its contribution to extraction-socket healing were evaluated using Pad4 −/− mice. In vitro, healthy-derived NETs (H-NETs) and T1D-derived NETs (D-NETs) were compared for their effects on BMSCs osteogenesis, proliferation, apoptosis, oxidative stress, and signaling. TSPAN11 function was examined by knockdown and overexpression. T1D was associated with fewer osteogenic-prone and more adipogenic-prone BMSCs subpopulations and reduced osteogenic gene expression. Diabetic extraction sockets showed excessive NETs accumulation, whereas PAD4 deficiency reduced NETs formation and partially improved bone regeneration. Compared with H-NETs, D-NETs more strongly impaired osteogenesis and proliferative activity, increased apoptosis and oxidative stress, and induced greater ERK1/2 activation. D-NETs also downregulated TSPAN11; TSPAN11 depletion impaired osteogenesis, whereas its overexpression alleviated D-NETs-induced inhibition. D-NETs contribute to impaired bone regeneration under T1D conditions by exerting enhanced detrimental effects on BMSCs function. Persistent ERK1/2 activation and TSPAN11 downregulation both contribute to D-NETs-induced osteogenic impairment. Targeting excessive NETs formation and its downstream effects on BMSCs may provide a potential strategy for improving bone healing in T1D.