["Journal of Cellular Physiology, Volume 241, Issue 5, May 2026. ", "\n\n\n\n\n\nABSTRACT\nThe ontogenic development of hematopoietic stem cells (HSCs) occurs across diverse niches, with HSCs migrating from the aorta‐gonad‐mesonephros (AGM) to the fetal liver and finally residing in the bone marrow after birth, where adult HSCs replenish the hematopoietic system. The HSC niche critically regulates tropism and proliferation via factors secreted by the microenvironment interaction. Here, we hypothesized that HSCs display tropism toward the aggressive cancer stem cell (CSC) niches of triple‐negative breast cancer (TNBC) and MCF‐7 cells breast cancer, which exhibit high relapse rates and are potential targets for cell therapy. Our results demonstrate HSC‐specific tropism toward breast CSCs, leading to interactions that trigger HSC differentiation into CD4+ and CD8+ subpopulations within the cancer microenvironment. Proteomics of migrated HSCs toward TNBC‐CSCs/MCF‐7 cells revealed significant upregulation of IL‐7, Notch, and other proteins involved in T cell activation and migration pathways. Metabolomics of HSC‐conditioned medium (HSC‐CM)‐treated CSCs/MCF‐7 cells further demonstrated that HSC‐CM arrests TNBC‐CSC growth and cell cycle progression by altering the mitochondrial bioenergetics. This study highlights the potential of leveraging both HSCs and HSC‐derived factors for personalized therapies targeting CSCs in TNBC."]