AAHS ASPN ASRM - 2013 Annual Meeting - American Association ...

Role of Graft-Derived Dendritic Cells in Skin Allograft Acceptance in Hemifacial Allograft Transplant Model
Institution where the work was prepared: The Cleveland Clinic Foundation, Cleveland, OH, USA
Aleksandra Klimczak, PhD; Galip Agaoglu; Sakir Unal; Maria Siemionow; The Cleveland Clinic Foundation
Introduction:
Clinical application of composite tissue allograft transplants opened discussion on the restoration of facial deformities by allotransplantation. We have formerly
achieved operational tolerance in fully MHC mismatched rat hemifacial allotransplantation model under low dose of cyclosporine-A (CsA) monotherapy without
side effect. The potential of graft-derived dendritic cells (DC) contribution to chimerism induction and allograft survival was tested in hemiface transplants,
across MHC barrier, under CsA monotherapy.
Methods:
Twenty four hemiface transplantations were performed in 4 groups (6 rats each). Allograft rejection controls included transplantation between semi-allogenic
LBN(RT1l+n) (Group 1) and fully-allogenic ACI(RT1a) (Group 2) donors without treatment. In allograft treatment groups, recipients of LBN grafts (Group 3)
and ACI grafts (Group 4) were treated with CsA monotherapy at dose of 16 mg/kg/day, tapered to 2 mg/kg/day and maintained at this level thereafter.
Evaluations were scheduled at different time-point (7, 28, 63, 100 days) for the lymphoid organs and blood harvesting. Flow cytometry monitored donor-specific
chimerism (MHC class-I RT1n and RT1a antigens). Immunofluorescence evaluated migratory potential of donor cells from face graft to lymphoid organs.
Mechanism of allograft acceptance was assessed by the presence of donor dendritic cells (DDC) and apoptotic cells (TUNEL technique) within lymphoid organs
of recipients.
Results:
All face transplants under CsA monotherapy from LBN and ACI donors displayed presence of passenger leukocytes within lymphoid organs of recipients. At day
7 post-transplant DDC and donor leukocytes were detected within spleen and lymph nodes of face recipients. During follow-up, the number of donor-origin
DC significantly increased within spleen but only single cells were present within lymph nodes. DDC were not detected within thymus. Donor-specific chimerism
was present in the peripheral blood of recipients at day 100 post-transplant: for LBN recipients 1.4% CD4/RT1n, 0.5% CD8/RT1n and 2.6% CD45RA/RT1n;
for ACI recipients 16.8% CD4/RT1a, 3.7% CD8/RT1a Apoptotic cells were detected in the lymphoid organs of recipients as early as day 7 and during entire
follow-up period (100 days) and reflected anergy of T-cells.
Conclusions:
CsA monotherapy promoted T-cell tolerogenicity of DDC in hemifacial allograft transplants due to stabilized functionally immature status of dendritic cells.
Migration and localization of graft-derived DDC into lymphoid organs of recipients confirmed immunomodulatory function of DDC in skin allograft acceptance
in hemifacial allograft model. Anergy of T cells, demonstrated by the presence of apoptotic cells within lymphoid organs of face recipients, contributed
to long-term hemifacial skin allograft survival.
Functional Study of Motor and Sensory Recover of Facial Allotransplantation. Experimental Study in Rats
Institution where the work was prepared: Clinica Aston, Valencia, Spain
Pedro C. Cavadas, MD, PhD; Luis Landin; Clinica Aston
Background:
Facial transplantation has raised enormous interest recently. Although there are animal models and two recent clinical cases, the functional recovery of a face
allotransplantation has not been demonstrated so far. The authors studied the motor and sensory recovery of a hemifacial allotransplantation in the rat model.
Material and Methods:
20 Wistar-Lewis RT1 rats were divided into 2 groups. In group A (10 rats) a hemifacial transplantation from Long-Evans rats was performed without nerve
repairs. In group B (10 rats) the hemifacial transplantation was performed from Long-Evans rats, with surgical repair of the infraorbitary branch of the trigeminal
nerve and the bucolabial, upper marginal mandibular and zygomaticoorbitary branches of the facial nerve. Monotherapy with tracrolimus (8 mg/Kg/day,
tapering down to 2 mg/Kg/day at 4 weeks and thereafter) was administered to both groups. Due to the 50% perioperative mortality, approximately twice as
many rats were operated on in both groups to obtain 10 survivors. At 6 weeks electroneurography and electromyography were obtained. Sensory recover was
assessed by the withdrawal reaction to whisker pull.
Results:
There was 50% perioperative mortality. Nerve conduction studies in the facial nerve showed no conduction in group A, and a somewhat delayed nerve action
potential in group B. Electromyography showed complete denervation of the mystacial muscles in group A, and a rich motor activity in group B. Withdrawal
reaction was absent in animals from the group A, whereas in group B the reaction was brisk.
Conclusions:
Motor and sensory recover has been demonstrated in hemifacial allotransplantation through major histocompatibility barrier under monotherapy immunesupression.
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