Background: Cell-based therapies represent a new promising strategy for tolerance induction in transplantation. One of the methods for immune response modulation in solid organ and vascularized composite allograft (VCA) recipients is donor bone marrow (BM) transplantation. We propose a new cellular therapy based on application of the ex vivo created donor-recipient chimeric cells as an alternative approach to BM-based therapies in support of solid organ and VCA transplantation. The aim of this study was to evaluate the tolerogenic potential of bone marrow-derived human hematopoietic chimeric cells (HHCCs) in vitro and assess their survival, migratory pathways and engraftment in vivo.

Methods: Thirty-eight ex vivo fusions were performed to create HHCCs. Briefly, CD34+ cells from two bone marrow (BM) donors were stained separately with PKH26 and PKH67 dyes and fused with polyethylene glycol. Double PKH26 and PKH67 stained cells were sorted and subjected to PCR-rSSOP, MLR assay and real-time PCR. HHCCs (1-2[times]10⁶) were injected intravenously or intraosseously to the nude rat recipients and their presence in peripheral blood (PB), BM, and lymphoid organs was detected by anti-human HLA-ABC staining and evaluated by confocal microscopy (CM) and flow cytometry (FC).

Results: HHCC creation was confirmed by FC and CM. PCR-rSSOP results showed that HHCCs share HLA class I and II specific for both fusion donors. HHCCs have tolerogenic potential as they express pro-tolerogenic cytokines (IL-10 and TGF-β) and decrease immune system response. In vivo studies indicated that HHCCs were present in PB of the nude rat recipients up to 42 days after their intraosseous and intravenous injection. Additionally, they also migrated from the injected to the contralateral bone and to the lymphoid organs (lymph nodes, spleen, liver). The number of HHCCs in the nude rat peripheral blood and bone marrow was higher after intraosseous cell delivery (0.58% and 6.58%, respectively) when compared to intravenous HHCC delivery (0.11% and 1.8%, respectively).

Conclusions: In vitro and in vivo studies confirmed the tolerogenic potential, engraftment and long-term survival of HHCCs. Application of HHCCs as a supportive therapy represents a novel approach for tolerance induction in transplant surgery.

CITATION INFORMATION: Siemionow M, Bryndza Tfaily E, Szilagyi E, Cwykiel J, Uygur S, Czerwinski M. Tolerogenic Potential, Migratory Pathways, Engraftment and Long-Term Survival of Human Hematopoietic Chimeric Cells – A Novel Strategy to Induce Tolerance in Transplantation. Am J Transplant. 2017;17 (suppl 3).

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