Exosome-mediated hematopoietic rejuvenation in a humanized mouse model indicate potential for cancer immunotherapy

Aging is associated with increased morbidity and high economic costs due to a burdened healthcare system and decreased workforce. Parabiotic animal models indicated that secretome from young cells can restore aged tissue functions. We used a heterochronic co-culture system with young and aged mobilized peripheral blood (MPB) or umbilical cord blood (UCB) and showed hematopoietic restoration, independent of allogeneic difference. Bidirectional communication between the aged and young cells influenced the miRNA cargo of exosomes, resulting in partial reprograming of the aged cells. The restored cells enhanced hematopoiesis (e.g., increased lymphoid:myeloid ratio) in immunodeficient mice bearing autologous aged hematopoietic system. Four exosomal miRNAs targeting PAX and PPMIF were partly responsible for the hematopoietic rejuvenation. Notably, increased natural killer (NK) cells within the restored cells eliminated dormant breast cancer cells in vivo . The findings could be developed as preventive measure and treatment for sustained immune/hematopoietic competence with potential for immunotherapy.