Human umbilical MSC-derived exosomes improve intracerebral hemorrhage recovery via SIRT1-driven suppression of NF-κB/NOS2 signaling: coordinating microglial homeostasis and neuroprotection

Abstract Intracerebral hemorrhage (ICH) remains a devastating neurological disorder with high mortality, driven primarily by uncontrolled neuroinflammation and secondary brain injury. Here, we show that human umbilical mesenchymal stem cell-derived exosomes (hUMSC-Exos) robustly promote functional recovery in a murine ICH model by reprogramming microglial biology and mitigating neuronal damage, via a mechanism dependent on the NAD⁺-dependent deacetylase SIRT1. Intranasal delivery of hUMSC-Exos enabled efficient uptake by perihematomal microglia, astrocytes, and neurons, reducing neuronal apoptosis and improving both sensorimotor and cognitive outcomes. Microglia-specific transcriptomic profiling revealed that hUMSC-Exos suppressed ICH-induced proinflammatory gene networks, particularly those governed by NF-κB/NOS2 signaling, while attenuating pathological microglial proliferation. Mechanistically, hUMSC-Exos upregulated SIRT1, which repressed NF-κB nuclear translocation and subsequent NOS2 expression. Pharmacological inhibition of SIRT1 with EX527 abrogated key beneficial effects of hUMSC-Exos: it reversed the suppression of microglial proliferation, restored neuronal apoptosis to ICH levels, and eliminated improvements in locomotor activity, anxiety-like behavior, and spatial learning/memory—assessed via open field and Morris water maze tests. Conversely, NOS2 blockade recapitulated the neuroprotective actions of hUMSC-Exos. Beyond anti-inflammatory effects, hUMSC-Exos promoted transcriptional programs linked to tissue remodeling and vascular regeneration, underscoring their dual role in mitigating injury and enhancing repair. Collectively, our study identifies a SIRT1-dependent axis through which stem cell-derived exosomes orchestrate microglial homeostasis and neuronal survival after ICH, establishing exosome-based therapy as a promising cell-free strategy for acute brain injury with translational potential.