Heat shock preconditioning potentiates the therapeutic efficacy of mesenchymal stem cells for traumatic brain injury.

Traumatic brain injury (TBI) is a serious disease characterized by a high incidence in young people and can lead to significant neurological impairment. Deterioration in cognitive function following TBI is often underpinned by a sustained neuroinflammatory state, which impairs the integrity of the blood-brain barrier (BBB) and accelerates neuronal loss. Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic approach for TBI because of their regenerative and immunomodulatory properties. Here, we identified heat shock (HS) pretreatment as an effective method to potentiate the therapeutic function of umbilical cord-derived MSCs for TBI. HS preconditioning modulated MSC biological properties, including upregulation of immunomodulatory genes and enhanced expression of heat shock protein 70 (Hsp70) and matrix metalloproteinase-2 (MMP2). Functionally, HS significantly improved migratory potential of MSCs in vitro and enhanced their homing efficiency to the injury site in vivo. In a TBI mouse model, the administration of HS-pretreated MSCs (HS-MSCs) improved cognitive outcome, protected against BBB infiltration and alleviated neuroinflammatory responses. In vitro, HS-MSCs exhibited enhanced immunomodulatory effects on microglia, including reduced expression of proinflammatory mediators and a shift toward an anti-inflammatory phenotype. Additionally, HS-MSC treatment was associated with decreased expression of key components of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway. Collectively, these findings suggest that HS preconditioning may enhance the therapeutic potential of MSCs in TBI, potentially through modulation of neuroinflammatory processes.