• Jan A Plock, Jonas T Schnider, Riccardo Schweizer, Wensheng Zhang, Wakako Tsuji, Matthias Waldner, Mario G Solari, Kacey G Marra, J Peter Rubin, and Vijay S Gorantla.
• 1 Department of Plastic Surgery, University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA. 2 McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA. 3 Department of Plastic Surgery and Hand Surgery, University Hospital Zurich (USZ), Zurich, Switzerland. 4 Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA.
• Transplantation. 2017 Jan 1; 101 (1): e1-e11.

BackgroundCellular therapies for immunomodulation in vascularized composite allotransplantation (VCA) have gained importance due to their potential for minimization of immunosuppression. Adipose-derived (AD) mesenchymal stem cells (MSCs) especially have shown encouraging potential. We investigated the influence of timing and frequency of AD-MSC treatment on immunologic and graft survival as well as graft vasculopathy outcomes after VCA.MethodsLewis rats received full-mismatched Brown Norway rat hindlimb transplants. Recipient animals were assigned to groups receiving donor-derived AD-MSCs (10 cells/animal) either on postoperative day (POD) 1, POD 4, or repeatedly on POD 4, 8, and 15, and compared to untreated controls.ResultsAlthough AD-MSC administration on POD 1 or POD 4, 8, and 15 resulted in 50% long-term graft acceptance, recipients treated on POD 4, and controls rejected before POD 50. All treated animals revealed peripheral blood chimerism (4 weeks), most pronounced after repetitive cell administration (12.92% vs 5.03% [POD 1] vs 6.31% [POD 4]; P < 0.05; all P < 0.01 vs control 1.45%). Chimerism was associated with the generation of regulatory T cells (CD4CD25FoxP3). In vitro mixed lymphocyte reactions revealed modulation of the recipient immune response after AD-MSC treatment. Graft arteries at end point revealed significant differences of arterial intimal thickness between rejecting and AD-MSC-treated animals (P < 0.01).ConclusionsTaken together, our results point to the potential for repetitive AD-MSC administration in improving outcomes after VCA. Future studies are warranted into optimization of the dosing and frequency of AD-MSC therapy, either alone or used in, combination with other cell therapies (such as hematopoietic stem cells or bone marrow-derived MSC or dendritic cells) for optimization of appropriate conditioning or maintenance regimens.

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