*Purpose: Solid organ transplantation is the therapy of choice for many patients with end-stage organ failure, but recipients must remain on lifelong immune suppression, leaving them susceptible to infections and cancer. The study of transplant tolerance to prolong graft survival in the absence of immunosuppression has been restricted to recipients of living donor allografts, yet deceased donors significantly outnumber living donors. In this study, we investigated the potential to obtain a reliable source of hematopoietic stem cells (HSCs) via mobilization into the peripheral blood for apheresis collection, towards the goal of enabling clinical trials of tolerance following deceased donor transplantation. Mobilization of HSCs from the bone marrow to the peripheral blood could allow PB-HSCs to be obtained from deceased donors, and be used to induce tolerance in the kidney recipient; however, a major concern is the well-known concomitant mobilization of immune cells into the liver. As 95% of transplanted livers are obtained from an already limited pool of deceased donors, the field cannot afford any further reduction in available organs.

*Methods: We mobilized HSCs to the peripheral blood using a protocol of two doses of GCSF and one dose of Plerixafor followed by collection of mobilized cells via apheresis in three deceased donors. Physiologic, laboratory and radiographic parameters were monitored throughout the procedure. Longitudinal biopsies were obtained to assess the potential for ectopic mobilization into the liver.

*Results: Physiologic, laboratory and radiographic parameters remained stable throughout the procedure. The use of both agents led to successful mobilization of peripheral blood CD34+ cells, sufficient for most transplant tolerance protocols. Increased immune cell trafficking into the liver was not observed, and apheresis of mobilized cells resulted in a uniform decrease in all liver leukocyte subsets.

*Conclusions: HSCs can be mobilized and collected from the peripheral blood of brain-dead donors. This new approach may facilitate dissemination of immune tolerance trials beyond living donor kidney transplantation to deceased donor transplantation, without sacrificing the liver’s transplantability. As most transplant procedures are from deceased donors, recipients of other solid organs as well as vascularized composite allografts would therefore become candidates for immune tolerance trials.

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