Journal of Blood & Lymph

Since regenerative therapy with stem cells is believed to exert an effect based on their proliferation and differentiation potential, anything that would cause the loss of these capacities, such as irradiation, may negate the anticipated effect. In this study, X-irradiated (XR) mononuclear cells were prepared from umbilical cord blood. Even though hematopoietic stem/progenitor cell activity was diminished in the XR cells, the regenerative activity was surprisingly conserved and aided recovery from experimental stroke in mice. Here, we provide evidence indicating the possible therapeutic mechanisms by which damaged cerebrovascular endothelial cells may be rescued by low-molecular-weight metabolites supplied by injected XR cells via gap junctions as energy sources to improve blood flow in the infarcted area. Thus, XR cells may exhibit tissue repair capabilities through the activation of endothelial cells, rather than via cell-autonomous effects.