Targeting BRD4 to reshape the inflammatory microenvironment of senescent bone marrow mesenchymal stem cells for improved hematopoietic stem cell transplantation reconstitution

Abstract Aims Chemotherapy-induced senescence of bone marrow mesenchymal stem cells (BMSCs) and concomitant hypersecretion of inflammatory factors are key factors driving hematopoietic microenvironment imbalance and impairing post-transplantation hematopoietic stem cell (HSC) reconstitution. This study aims to elucidate the regulatory mechanism of inflammatory factor expression in senescent BMSCs and explore a microenvironment-remodeling strategy via BRD4-targeted intervention. Methods We established an in vitro cell model for the induction of BMSCs' senescence by DNA-damaging drugs. Explore the mechanism through molecular intervention using siRNA, inhibitors, or senolytic drugs. And phenotypic analysis was conducted using qPCR, ELISA, and SA-β-gal staining methods. Functional validation was conducted through in vitro co-culture of senescent BMSCs with HSCs, followed by HSC colony-forming assays Results BRD4 knockdown significantly suppressed inflammatory factor transcription in senescent BMSCs . This phenomenon was recapitulated pharmacologically using the BRD4 inhibitor JQ1, which demonstrated dose-dependent suppression of senescence-associated secretory phenotype (SASP) factors. Crucially, dual-pathway intervention combining senolytic agents (dasatinib + quercetin, D+Q) with JQ1 exhibited synergistic efficacy, reducing SASP secretion more substantially than either monotherapy. Functional validation revealed that this combinatorial approach restored hematopoietic support capacity, with treated senescent BMSCs enhancing colony-forming units of co-cultured HSCs compared to untreated controls. Conclusion Our findings establish BRD4 as a critical regulator of chemotherapy-induced BMSC senescence and inflammatory factor expression. We further demonstrate that a novel dual-pathway strategy combining senescent cell clearance (via dasatinib + quercetin) with BRD4 inhibition synergistically restores the inflammatory hematopoietic microenvironment. This approach offers a promising therapeutic solution for improving post-transplantation HSC reconstitution, with BRD4-targeted interventions demonstrating significant potential for clinical translation.