Gerald Brandacher

Reconstruction of Large Abdominal Wall Defects Using Neurotized Vascular Composite Allografts.

Background: Abdominal wall vascularized composite allotransplantation is the second most common form of vascularized composite allotransplantation. Sensory and functional recovery are expected in other forms but have never been demonstrated in abdominal wall vascularized composite allotransplantation. The authors hypothesize that coaptation of two thoracolumbar nerves will result in reinnervation of the alloflap and maintenance of the muscle component. Methods: Adult, male, 10-week-old Brown Norway and Lewis rats were used for experiments. The rat donor’s common iliac vessels were anastomosed to the recipient’s femoral vessels. Intercostal nerves T10/L1 were coapted. Four groups (n = 5 per group) were included for study: group 1, Lewis, intercostal nerves cut, not repaired; group 2, Lewis intercostal nerves cut, T10/L1 repaired; group 3, allogeneic Brown Norway–to-Lewis abdominal wall vascularized composite allotransplantation, T10/L1 repaired; and group 4, syngeneic Lewis-to-Lewis abdominal wall vascularized composite allotransplantation, T10/L1 repaired. Animals were killed on postoperative day 60. Nerve regeneration was assessed using muscle weight analysis, myofibril cross-sectional area, nerve histomorphometry, and neuromuscular junction percentage reinnervation. Results: Groups 2, 3, and 4 maintained a significantly greater percentage of postharvest weight compared with group 1 (p < 0.05). Group 1 had significantly decreased myofibril cross-sectional area compared with controls (p < 0.05). There was no significant difference in myofibril cross-sectional area in groups 2 through 4 compared with controls (p > 0.05). Group 1 had significantly decreased percentage reinnervation of the alloflap compared with controls (p < 0.05). There was no significant difference when comparing group 2 through 4 with internal, contralateral controls (p > 0.05). Conclusion: In a murine model for abdominal wall vascularized composite allotransplantation, coaptation of T10/L1 will allow for reinnervation of the alloflap and maintenance of the muscle component.

Abstract 9: selectively permeable nanofiber constructs to prevent inflammatory scarring and enhance nerve regeneration in peripheral nerve injury.

ConClusion: Endothelial cell-stromal interactions, mediated by SDF-1, play a pivotal role in maintaining ASC niche transcriptional homeostasis and preserving the functional capacity of ASCs. In the absence of SDF-1, ASCs are shunted towards adipogenesis, with reduced proliferative and proangiogenic capacity, impacting their physiological role within the adipose niche environment and their therapeutic potential in treating ischemia. The dysfunction of ASCs in diabetes may be related to downregulation of SDF-1 and subsequent disruption of the physiological cytokine milieu. Further investigation of the role of SDF-1 in ASC homeostasis and function, particularly in the context of diabetes, is ongoing to inform the development of autologous cell based therapies for diabetic wound healing. 9 Selectively Permeable nanofiber constructs to Prevent inflammatory Scarring and enhance nerve regeneration in Peripheral nerve injury

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.

Abstract 121: INVESTIGATING THE IMMUNOREGULATORY PROPERTIES OF ADIPOSE-DERIVED STEM CELLS IN AN IN VITRO MOUSE MODEL OF RECONSTRUCTIVE TRANSPLANTATION

Methods: Plastic-adherent ASCs isolated from C57B6 and Balb/c mice were cultured in high-glucose Dulbecco Modiuf0de ed Eagle Medium, 10% FBS, and 1% penicillin-streptomycin and used at passages 2-5. Flow cytometry was performed to identify surface markers consistent with the ASC phenotype. CFSE-stained C57B6 splenocytes were cultured in a 1:1 ratio with mitomycin-treated Balb/c splenocytes (allogeneic stimulation) or with mitomycin-treated, non-CFSE-stained C57B6 splenocytes (control). Stimulated and control wells were cultured with varying doses of ASCs from C57B6 and Balb/c origin. Samples were harvested at day 4, incubated with anti-mouse CD3 antibody, and analyzed for proliferation via uf0df ow cytometry.

Abstract 117: CUTANEOUS LYMPHATIC RECONSTITUTION OCCURS DURING THE ACUTE INFLAMMATORY PHASE IN A RAT ORTHOTOPIC HIND LIMB TRANSPLANTATION MODEL

Background: Vascularized composite allotransplantation (VCA) has become a prominent reconstructive option for patients suffering major tissue loss. Wider application is limited by the need for chronic immunosuppression. Recent data suggest that the cutaneous lymphatic system plays an important role in mediating allograft rejection. However, little is known about lymphatic reconstitution in VCA. The purpose of this study was to describe cutaneous lymphatic reconstitution in rat orthotopic hind-limb transplants using near-infrared (NIR) lymphography.

34A: TITRATION OF BONE MARROW CELL INFUSION IN A PRECLINICAL MODEL OF COMPOSITE TISSUE ALLOTRANSPLANTATION

Introduction: Composite tissue allotransplantation (CTA) has become a clinical reality with excellent functional results and most encouraging short and intermediate outcomes. However, recipients still require lifelong multi-drug immunosuppression to prevent graft rejection. While ensuring graft survival these regimens carry a high risk for serious side effects. Current research therefore focuses on developing strategies to minimize or avoid immunosuppression for such nonlife saving procedures. In this regard we have developed a preclinical model of heterotopic hindlimb transplantation in Yucatan miniature swine using recipient conditioning, donor bone marrow infusion, and monotherapy immunosuppression. Our current study aims to determine the optimal dose of bone marrow cells to be infused to establish stable mixed chimerism.