Rejuvenation of mesenchymal stem cells by human peripheral blood lymphocytes: A dual-mechanism for targeting senescent cell clearance and promoting cell proliferation in a coculture system

Background : In the in-vitro expansion of mesenchymal stem cells (MSCs), replicative or stress-induced senescence poses a significant challenge, leading to the loss of their cellular properties and therapeutic functions. Currently, there is a lack of efficient strategies to address this issue. Methods : Here we presented a novel approach to combat cellular senescence and promote cell proliferation by coculturing human MSCs with human peripheral blood lymphocytes (PBLs). After the treatment of PBL with MSCs from the tenth passage (P10), the secretion profile of PBLs was assessed by RNA sequencing. RNA-seq and iTRAQ quantitative proteomics-seq analyses were used to determine the transcriptomic and proteomic changes, respectively. Results : In a heterogeneous population of MSCs comprising both aged and nonaged cells, PBL effector cells, rather than their cytokines, exhibited a dual role. They selectively induced apoptosis in aged cells by facilitating p53 SUMOylation and activating the p53-dependent mitochondrial pathway, while simultaneously safeguarding younger cells against senescence and promoting cell proliferation by activating Serpinb2/NF-κB signaling. This resulted in a decrease in aged MSCs and an enrichment of rejuvenated MSCs. This process effectively reversed the senescence phenotype, leading to the remodeling of stemness characteristics and the enhancement of functionality within the MSC population.Furthermore, MSCs rejuvenated by PBLs presented an enhanced therapeutic efficacy and a favorable safety profile. Conclusion : PBLs rejuvenate MSCs by promptly removing aged cells and enhancing the stemness and proliferative capacity of nonaged cells. This work provides an ideal method for obtaining substantial MSCs while meeting the quality requirements for stem cell therapy.