HIV‐1 p55‐gag protein induces senescence of human bone marrow mesenchymal stem cells and reduces their capacity to support expansion of hematopoietic stem cells in vitro

Patients with human immunodeficiency virus-1 (HIV-1) infection often present with hematopoietic failure. As the important hematopoietic support cells in the bone marrow (BM), the bone marrow mesenchymal stem cells (BMSCs) can be impacted by HIV proteins that are released by infected cells within BM. In this study, we tested whether HIV protein p55-gag could induce senescence of BMSCs and reduce their capacity to support expansion of hematopoietic stem cells in vitro. BMSCs were chronically treated with p55-gag (BMSCgag) for up to 20 days, and their proliferative activity and senescence makers were compared to nontreated cells (BMSCcon). Then, we analyzed the .hematopoietic support function of BMSCcon and BMSCgag by determining cellular proliferation, colony-forming ability and primitive hematopoietic populations of hematopoietic progenitors grown on the BMSCs. In addition, we compared the gene expression patterns for supporting hematopoiesis of BMSCcon and BMSCgag. The results show that when compared to BMSCcon, BMSCgag reduced their proliferative activity and underwent senescence. The ability of BMSCgag to support the expansion of committed hematopoietic progenitors from umbilical cord blood-derived CD34+cells may be impaired, while the expression of genes associated with maintaining and enhancing hematopoiesis appeared to be decreased in treated BMSCs compared to control BMSCs. In conclusion, senescence induced by p55-gag resulted in decreased .hematopoietic support function of BMSCs through reducing a series of hematopoietic cytokine expression.