W. P. Andrew Lee

Composite tissue vasculopathy and degeneration following multiple episodes of acute rejection in reconstructive transplantation.

Transplant vasculopathy has not been systematically investigated in composite tissue allotransplantation (CTA). The impact of multiple acute rejections (ARs) on long‐term graft outcomes in reconstructive transplantation remains unknown. This study in a rat hind‐limb allotransplantation model systematically analyzes vasculopathy and tissue‐specific pathological changes secondary to multiple AR episodes. LEW rats were transplanted with BN rat hind limbs and treated as follows: Group 1 (Iso): isografts. Group 2 (CsA): Cyclosporine (CsA) qd; Group 3 (mult AR): CsA and dexamethasone only when AR was observed. No AR was observed in Groups 1 and 2. Multiple AR were observed in Group 3, and each episode was completely reversed (clinically) with pulsed CsA + dexamethasone treatment. Group 3 animals demonstrated significant vascular lesions along with skin and muscle atrophy, upregulation of profibrotic gene expression and fibrosis when compared to Groups 1 and 2. In addition, allograft bone was sclerotic, weak and prone to malunion and nonunion. Interestingly, vasculopathy was a late finding, whereas muscle atrophy with macrophage infiltration was seen early, after only a few AR episodes. Taken together, multiple AR episodes lead to vasculopathy and tissue‐specific pathology in CTA. This is the first evidence of ‘composite tissue vasculopathy and degeneration (CTVD)’ in CTA.

Daily topical tacrolimus therapy prevents skin rejection in a rodent hind limb allograft model.

Background: Skin is the most immunogenic component of a composite tissue allograft. Topical immunotherapy is an attractive therapeutic modality with which to provide local immunosuppression, with minimal systemic toxicity. The present study was performed to investigate the potential of topical tacrolimus to prolong survival of the skin component of a composite tissue allograft. Methods: Wistar Furth–to-Lewis rat orthotopic hind limb transplants were performed. Group I consisted of rats treated with topical tacrolimus; group II, antilymphocyte serum plus 21 days cyclosporine; and group III, antilymphocyte serum plus 21 days of cyclosporine plus topical tacrolimus. In group IV, tacrolimus levels in blood, skin, and muscle were measured in an autograft control group. Results: All animals in group I (n = 8) developed grade III clinical rejection by postoperative day 9. In group II (n = 9), the median onset of grade III rejection was postoperative day 40 (range, postoperative days 34 to 44). In group III (n = 6), two animals developed focal grade III rejection on postoperative days 35 and 56. The remaining four animals reached the 100-day endpoint without grade III rejection. In group IV, tacrolimus levels were low or undetectable in blood, whereas skin levels were 100-fold higher than underlying muscle. Conclusions: Topical tacrolimus therapy has the potential to prevent skin rejection in a composite tissue allograft. Preoperative depletion of T cells with antilymphocyte serum, along with a short course of systemic immunosuppression, prevents acute rejection, whereas topical tacrolimus inhibits immune cell function in the skin. Concentrations of tacrolimus are substantially higher in skin compared with underlying muscle and peripheral blood. Topical immunotherapy could reduce the morbidity associated with systemic immunosuppression in clinical composite tissue allografts.

A Model for Functional Recovery and Cortical Reintegration after Hemifacial Composite Tissue Allotransplantation

Background: The ability to achieve optimal functional recovery is important in both face and hand transplantation. The purpose of this study was to develop a functional rat hemifacial transplant model optimal for studying both functional outcome and cortical reintegration in composite tissue allotransplantation. Methods: Five syngeneic transplants with motor and sensory nerve appositions (group 1) and five syngeneic transplants without nerve appositions (group 2) were performed. Five allogeneic transplants were performed with motor and sensory nerve appositions (group 3). Lewis (RT1l) rats were used for syngeneic transplants and Brown-Norway (RT1n) donors and Lewis (RT1l) recipients were used for allogeneic transplants. Allografts received cyclosporine A monotherapy. Functional recovery was assessed by recordings of nerve conduction velocity and cortical neural activity evoked by facial nerve and sensory (tactile) stimuli, respectively. Results: All animals in groups 1 and 3 showed evidence of motor function return on nerve conduction testing, whereas animals in group 2, which did not have nerve appositions, did not show electrical activity on electromyographic analysis (p < 0.001). All animals in groups 1 and 3 showed evidence of reafferentation on recording from the somatosensory cortex after whisker stimulation. Animals in group 2 did not show a cortical response on stimulation of the whiskers (p < 0.001). Conclusion: The authors have established a hemiface transplant model in the rat that has several modalities for the comprehensive study of motor and sensory recovery and cortical reintegration after composite tissue allotransplantation.

Functional outcomes following multiple acute rejections in experimental vascularized composite allotransplantation

Background: Vascularized composite allotransplantation has become a clinical reality. Patients undergoing vascularized composite allotransplantation have modest functional return. Most patients have had multiple acute rejections. The effect of multiple acute rejections influencing functional outcomes is unknown. This study systematically analyzes the effects of multiple acute rejections on functional outcome. Methods: Rat functional orthotopic hind-limb transplants were performed from Brown-Norway to Lewis rats. Group 1 consisted of isografts. In group 2, daily cyclosporine was administered to prevent acute rejection. In group 3, recipients did not receive regular immunosuppression but received only pulsed cyclosporine and dexamethasone to rescue acute rejection. The study endpoint was 90 days. Muscle and sciatic nerve biopsy specimens were taken for histologic analyses. Hind-limb function was assessed using sciatic nerve axon density, nerve conduction velocity, and muscle force generated by the gastrocnemius muscle. Novel video kinematics was used to analyze gait. Results: By the endpoint, group 3 animals had 17 ± 5.1 acute rejections. Muscle biopsy showed significant atrophy and fibrosis in group 3 compared with groups 1 and 2. Withdrawal to pin prick was evident by days 31 ± 1.2, 30 ± 2.3, and 31 ± 3.7 in groups 1, 2, and 3, respectively. At the endpoint, there was no significant difference in the axon density or nerve conduction velocity among the three groups, but muscle force generated was significantly less in group 3. Gait was abnormal in group 3 animals compared with other groups. Conclusions: In this study, multiple acute rejections induced muscle atrophy and fibrosis and consequent decreased function. This emphasizes the importance of preventing acute rejection to achieve optimum function following vascularized composite allotransplantation.

Transplantation of composite tissue allografts

Transplantation of composite tissue allografts / , Transplantation of composite tissue allografts / , کتابخانه دیجیتال جندی شاپور اهواز

Lower Extremity Allotransplantation: Are We Ready for Prime Time?

With the success of upper extremity and face transplantation, the field of vascularized composite allotransplantation (VCA) is preparing to expand into other reconstructive areas of the body. Lower extremity allotransplantation has the potential to offer patients improved function over current prosthetics, reduce phantom limb pain, and reduce prosthetic associated complications. However, these benefits must be weighed against the obstacles of slow-paced nerve regeneration, difficult perioperative management, and lifelong immunosuppression. Four cases of lower extremity transplantation have been performed with increasingly high-risk operations, marked by deaths of the last 2 recipients. As lower extremity allotransplantation proceeds, selecting the appropriate candidates to optimize outcomes is critical. We propose a classification system of lower extremity allotransplantation based on the extent of preservation of recipient muscular innervation and detail a practical next recipient. If a safe and thoughtful approach is taken, we believe lower extremity allotransplantation can achieve similarly positive results to those seen in hand and face allotransplantation.

Reconstructive Transplantation for Penile Restoration

Male genitourinary trauma often results in devastating physical and psychological sequellae. Traditional options for autologous reconstruction do not fully restore form and function and are prone to significant complications involving urinary strictures and fistulae as well as prosthesis extrusion; we believe that reconstructive transplantation may provide improved outcomes for select patients. Thus far, penile allotransplantation has been performed twice with mixed results. Prior to more widespread implementation, carefully attention must be directed toward minimizing the benefits and minimizing the risks associated with this procedure. There are also a number of ethical considerations unique to penile transplantation that must be considered. In this article, we review the potential risks, benefits and ethical considerations pertaining to penile transplantation and discuss approaches to optimize outcomes.

Technical Approach to Penile Transplantation

Penile transplantation may provide improved outcomes as compared to autogenous phalloplastic reconstruction. The optimal approach to vascularizing penile allografts is unknown. In penile replantation typically only the dorsal arteries are repaired, but utilizing the cavernosal and external pudendal arteries may improve erectile function and shaft skin perfusion, respectively. The authors sought to demonstrate the technical feasibility of utilizing the dorsal, cavernosal, and external pudendal vessels for penile transplantation and to assess differences in their perfusion territories.

Inhibition of JAK/STAT Signaling Synergizes with CTLA4-Ig to Promote Transplant Survival

Murine T cell activation was assessed through a CFSE proliferation assay. Activation in an inflamed environment was simulated through addition of supernatant (MATSup) from maturing dendritic cells. Jak inhibition was exerted with the inhibitor Tofacitinib (Tofa). Differential expression of DC maturation markers in response to LPS C/¡ Tofa was analyzed by flow cytometry. In vivo synergism between Tofa and CTLA4-Ig was tested in B6 to BALB/c heart and skin graft models.

Post Transplantation High-dose Cyclophosphamide (PTCy) to Promote Immune Tolerance After Reconstructive Transplantation

The life-long use of immunosuppressants and their associated toxicities remains one of the primary obstacles that curtail the wider use of VCAs for reconstruction. In this study we therefore investigated if the combination of bone marrow transplantation and high dose cyclophosphamide induces a state of long term allograft acceptance in the setting of full thickness skin transplantation and orthotopic hind limb transplantation in a mouse model.