Donor Recipient Chimeric Cells Induce Chimerism and Extend Survival of Vascularized Composite Allografts

Abstract

This study evaluated the efficacy of donor recipient chimeric cell (DRCC) therapy created by fusion of donor and recipient derived bone marrow cells (BMC) in chimerism and tolerance induction in a rat vascularized composite allograft (VCA) model. Twenty-four VCA (groin flaps) from MHC-mismatched ACI (RT1a) donors were transplanted to Lewis (RT1l) recipients. Rats were randomly divided into (n = 6/group): Group 1—untreated controls, Groups 2—7-day immunosuppression controls, Group 3—DRCC, and Group 4—DRCC with 7-day anti-αβTCR monoclonal antibody and cyclosporine A protocol. DRCC created by polyethylene glycol-mediated fusion of ACI and Lewis BMC were cultured and transplanted (2–4 × 106) to VCA recipients via intraosseous delivery route. Flow cytometry assessed peripheral blood chimerism while fluorescent microscopy and PCR tested the presence of DRCC in the recipient’s blood, bone marrow (BM), and lymphoid organs at the study endpoint (VCA rejection). No complications were observed after DRCC intraosseous delivery. Group 4 presented the longest average VCA survival (79.3 ± 30.9 days) followed by Group 2 (53.3 ± 13.6 days), Group 3 (18 ± 7.5 days), and Group 1 (8.5 ± 1 days). The highest chimerism level was detected in Group 4 (57.9 ± 6.2%) at day 7 post-transplant. The chimerism declined at day 21 post-transplant and remained at 10% level during the entire follow-up period. Single dose of DRCC therapy induced long-term multilineage chimerism and extended VCA survival. DRCC introduces a novel concept of customized donor-recipient cell-based therapy supporting solid organ and VCA transplants.

Creation of human hematopoietic chimeric cell (HHCC) line as a novel strategy for tolerance induction in transplantation

“…In addition, the increased expression of the pro-tolerogenic cytokine IL-10 and negligible expression of the proinflammatory Th1 cytokine (TNF-α) further confirmed immunomodulatory properties and tolerogenic potential of the created HHCC cell line. These findings are in line with our previous experimental studies confirming the tolerogenic effect of chimeric cells used to support different VCA transplants without immunosuppression protocol ( 13 , 15 ).…”

“…To address these limitations, for the past 20 years, our Laboratory has developed novel protocols for induction of tolerance via establishment of donor specific chimerism tested in different experimental models of VCA, including limb allograft transplant carrying vascularized BM component ( 8 - 15 ). Based on this experience confirming a crucial role of the vascularized BM component of donor origin in induction of donor specific chimerism, we have created DRCC via PEG-mediated fusion of BM cells derived from two unrelated donors ( 13 ). The tolerogenic potential of DRCC was confirmed in vivo by prolonged VCA survival and induction of mixed chimerism ( 13 ).…”

“…Based on this experience confirming a crucial role of the vascularized BM component of donor origin in induction of donor specific chimerism, we have created DRCC via PEG-mediated fusion of BM cells derived from two unrelated donors ( 13 ). The tolerogenic potential of DRCC was confirmed in vivo by prolonged VCA survival and induction of mixed chimerism ( 13 ). Thus, in the search of new, clinically applicable alternative approaches to BMT, we have created a new generation of human donor-derived chimeric cells (DCC) via ex vivo cell mediated fusion of BM-derived CD34 + cells and/or MSCs from two unrelated human donors.…”

“…Thus, there is an urgent need to develop new, cell-based therapies, which will extend allograft survival without the need for harmful conditioning protocols or life-long immunosuppression. New stem cell strategies are based on the tailored, customized approaches to address the individual patient needs and to change the current paradigm To address these limitations, for the past 20 years, our Laboratory has developed novel protocols for induction of tolerance via establishment of donor specific chimerism tested in different experimental models of VCA, including limb allograft transplant carrying vascularized BM component (8)(9)(10)(11)(12)(13)(14)(15). Based on this experience confirming a crucial role of the vascularized BM component of donor origin in induction of donor specific chimerism, we have created DRCC via PEG-mediated fusion of BM cells derived from two unrelated donors (13).…”

“…Our laboratory has over 20 years of research experience in chimerism induction and application of BM-based cell therapies in different VCA models (8)(9)(10)(11)(12)(13)(14)(15). These pioneering studies on tolerance induction in VCA encouraged us to create the donor-recipient chimeric cells (DRCC) via ex vivo, polyethylene glycol (PEG)-mediated fusion.…”