The Effects of Growth Hormone on Nerve Regeneration and Alloimmunity in Vascularized Composite Allotransplantation.

BACKGROUND: Poor outcomes in functional recovery following upper extremity transplantation are largely due to denervation-induced muscle atrophy that occurs during the prolonged period of nerve regeneration. Growth hormone (GH) has well-established trophic effects on neurons, myocytes, and Schwann cells and represents a promising therapeutic approach to address this challenge. This study sought to confirm the positive effects of GH treatment on nerve regeneration and functional recovery and to evaluate the effects of GH treatment on the immune response in the setting of vascularized composite allotransplantation. METHODS: Rats underwent orthotopic forelimb transplantation across a full MHC-mismatch and received either porcine-derived growth hormone or no treatment (n=18 per group). Functional recovery was measured using electrically-stimulated grip strength testing. Animals were monitored for clinical and subclinical signs of rejection. RESULTS: Neuromuscular junction reinnervation and grip strength were improved in GH-treated animals (p=0.005; p=0.08). No statistically significant differences were seen in muscle atrophy, degree of myelination, axon diameter, and axon counts between groups. The rates of clinical and histological rejection did not significantly differ among groups. CONCLUSIONS: Our findings alleviate concern for increased risk of transplant rejection during GH therapy and therefore support the translation of growth hormone as a therapeutic method to promote improved functional recovery in upper extremity transplantation.

Building an Academic Transgender Medicine Center of Excellence: The 5-Year Johns Hopkins Experience.

Gender-affirming care for transgender and gender diverse (TGD) individuals is a multidisciplinary endeavor that requires organized efforts of many specialized practitioners. TGD individuals experience many health care barriers, including the scarcity of multidisciplinary teams formed to coordinate and deliver complex care in an efficient and affirming way. The Johns Hopkins Center for Transgender Health was founded in 2017 with the mission of decreasing health disparities and improving the health of the TGD community. The authors present their experience building the center around a service line model in which patients have 1 point of contact, they are tracked throughout the care process, and the multidepartmental practitioners involved in their care are aligned. This model allowed for a patient-centered experience in which all involved disciplines were seamlessly integrated and the patient could navigate easily among them. With the structure and mission in place, the next challenge was to develop an infrastructure for culturally competent care. Through competency training and adjustment of systems-based logistics, measures were put in place to prevent traumatic experiences, such as misgendering, use of culturally inappropriate vocabulary, and use of incorrect names. Partnerships among colleagues in the fields of plastic surgery, urology, gynecology, otolaryngology, anesthesia, psychiatry/mental health, internal medicine, endocrinology, fertility, nursing, social work, speech therapy, and pediatrics/adolescent care were necessary to provide the appropriate breadth of services to care for TGD patients. Since its inception, the center has seen steady and continual growth, with more than 2,800 patients in its first 5 years. By sharing their experience in creating and developing a center of excellence, the authors hope to provide a blueprint for others to expand health care quality and access for TGD individuals.

Cortical reintegration after facial allotransplantation.

Neural plasticity of the brain or its ability to reorganize following injury has likely coincided with the successful clinical correction of severe deformity by facial transplantation since 2005. In this study, we present the cortical reintegration outcomes following syngeneic hemifacial vascularized composite allograft (VCA) in a small animal model. Specifically, changes in the topographic organization and unit response properties of the rodent whisker-barrel somatosensory system were assessed following hemifacial VCA. Clear differences emerged in the barrel-cortex system when comparing naïve and hemiface transplanted animals. Neurons in the somatosensory cortex of transplanted rats had decreased sensitivity albeit increased directional sensitivity compared with naïve rats and evoked responses in transplanted animals were more temporally dispersed. In addition, receptive fields were often topographically mismatched with the indication that the mismatched topography reorganized within adjacent barrel (same row-arc bias following hemifacial transplant). These results suggest subcortical changes in the thalamus and/or brainstem play a role in hemifacial transplantation cortical plasticity and demonstrate the discrete and robust data that can be derived from this clinically relevant small animal VCA model for use in optimizing postsurgical outcomes.NEW & NOTEWORTHY Robust rodent hemifacial transplant model was used to record functional changes in somatosensory cortex after transplantation. Neurons in the somatosensory cortex of face transplant recipients had decreased sensitivity to stimulation of whiskers with increased directional sensitivity vs. naive rats. Transplant recipient cortical unit response was more dispersed in temporary vs. naive rats. Despite histological similarities to naive cortices, transplant recipient cortices had a mix of topographically appropriate and inappropriate whiskered at barrel cortex relationships.

The Efficacy of Schwann-Like Differentiated Muscle-Derived Stem Cells in Treating Rodent Upper Extremity Peripheral Nerve Injury.

BACKGROUND: There is a pressing need to identify alternative mesenchymal stem cell sources for Schwann cell cellular replacement therapy, to improve peripheral nerve regeneration. This study assessed the efficacy of Schwann cell-like cells (induced muscle-derived stem cells) differentiated from muscle-derived stem cells (MDSCs) in augmenting nerve regeneration and improving muscle function after nerve trauma. METHODS: The Schwann cell-like nature of induced MDSCs was characterized in vitro using immunofluorescence, flow cytometry, microarray, and reverse-transcription polymerase chain reaction. In vivo, four groups (n = 5 per group) of rats with median nerve injuries were examined: group 1 animals were treated with intraneural phosphate-buffered saline after cold and crush axonotmesis (negative control); group 2 animals were no-injury controls; group 3 animals were treated with intraneural green fluorescent protein-positive MDSCs; and group 4 animals were treated with green fluorescent protein-positive induced MDSCs. All animals underwent weekly upper extremity functional testing. Rats were euthanized 5 weeks after treatment. The median nerve and extrinsic finger flexors were harvested for nerve histomorphometry, myelination, muscle weight, and atrophy analyses. RESULTS: In vitro, induced MDSCs recapitulated native Schwann cell gene expression patterns and up-regulated pathways involved in neuronal growth/signaling. In vivo, green fluorescent protein-positive induced MDSCs remained stably transformed 5 weeks after injection. Induced MDSC therapy decreased muscle atrophy after median nerve injury (p = 0.0143). Induced MDSC- and MDSC-treated animals demonstrated greater functional muscle recovery when compared to untreated controls (hand grip after induced MDSC treatment: group 1, 0.91 N; group 4, 3.38 N); p < 0.0001) at 5 weeks after treatment. This may demonstrate the potential beneficial effects of MDSC therapy, regardless of differentiation stage. CONCLUSION: Both MDSCs and induced MDSCs decrease denervation muscle atrophy and improve subsequent functional outcomes after upper extremity nerve trauma in rodents.

Reinventing Yourself Virtually: Fifth Annual Society of Asian Academic Surgeons Virtual Conference.

Virtual forms of communication have been integrated into academic surgery now more than ever. The COVID-19 pandemic accelerated its implementation in an effort to support social-distancing. Academic surgery is now learning valuable lessons from early experiences to optimally integrate this communication mode. The Society of Asian Academic Surgeons convened an expert panel during the society's fifth annual meeting that explores these lessons. Realms of virtual communication including meetings, networking, surgery department administration, social media, application processes, and advice for early or mid-career academic surgeons are explored. Virtual conferences pose a new challenge by removing the in-person component that is evident to be integral to networking, collaboration, and all aspects of academic socialization. Strategies such as creating virtual chat rooms, mentor-mentee virtual introductions, and deliberate interactions can enhance the experience. Virtual administrative meetings require special attention to preparation and strategies to insure engagement. Social media can be a valuable tool to integrate into academic careers but special attention needs to be made to utilize it deliberately and not to shy away from our individuality. The interview process can be enhanced when made virtual to give opportunities to those typically disadvantaged in the usual, in-person process.

The intragraft vascularized bone marrow component plays a critical role in tolerance induction after reconstructive transplantation.

The role of the vascularized bone marrow component as a continuous source of donor-derived hematopoietic stem cells that facilitate tolerance induction of vascularized composite allografts is not completely understood. In this study, vascularized composite tissue allograft transplantation outcomes between recipients receiving either conventional bone marrow transplantation (CBMT) or vascularized bone marrow (VBM) transplantation from Balb/c (H2d) to C57BL/6 (H2b) mice were compared. Either high- or low-dose CBMT (1.5 × 108 or 3 × 107 bone marrow cells, respectively) was applied. In addition, recipients were treated with costimulation blockade (1 mg anti-CD154 and 0.5 mg CTLA4Ig on postoperative days 0 and 2, respectively) and short-term rapamycin (3 mg/kg/day for the first posttransplant week and then every other day for another 3 weeks). Similar to high-dose conventional bone marrow transplantation, 5/6 animals in the vascularized bone marrow group demonstrated long-term allograft survival (>120 days). In contrast, significantly shorter median survival was noted in the low-dose CBMT group (~64 days). Consistently high chimerism levels were observed in the VBM transplantation group. Notably, low levels of circulating CD4+ and CD8+ T cells and a higher ratio of Treg to Teff cells were maintained in VBM transplantation and high-dose CBMT recipients (>30 days) but not in low-dose VBM transplant recipients. Donor-specific hyporesponsiveness was shown in tolerant recipients in vitro. Removal of the vascularized bone marrow component after secondary donor-specific skin transplantation did not affect either primary allograft or secondary skin graft survival.

Vascularized composite allotransplantation combined with costimulation blockade induces mixed chimerism and reveals intrinsic tolerogenic potential.

Vascularized composite allotransplantation (VCA) has become a valid therapeutic option to restore form and function after devastating tissue loss. However, the need for high-dose multidrug immunosuppression to maintain allograft survival is still hampering more widespread application of VCA. In this study, we investigated the immunoregulatory potential of costimulation blockade (CoB; CTLA4-Ig and anti-CD154 mAb) combined with nonmyeoablative total body irradiation (TBI) to promote allograft survival of VCA in a fully MHC-mismatched mouse model of orthotopic hind limb transplantation. Compared with untreated controls (median survival time [MST] 8 days) and CTLA4-Ig treatment alone (MST 17 days), CoB treatment increased graft survival (MST 82 days), and the addition of nonmyeloablative TBI led to indefinite graft survival (MST > 210 days). Our analysis suggests that VCA-derived BM induced mixed chimerism in animals treated with CoB and TBI + CoB, promoting gradual deletion of alloreactive T cells as the underlying mechanism of long-term allograft survival. Acceptance of donor-matched secondary skin grafts, decreased ex vivo T cell responsiveness, and increased graft-infiltrating Tregs further indicated donor-specific tolerance induced by TBI + CoB. In summary, our data suggest that vascularized BM-containing VCAs are immunologically favorable grafts promoting chimerism induction and long-term allograft survival in the context of CoB.

Clinical Characteristics of 90 Macrodactyly Cases.

PURPOSE: Macrodactyly is a rare, nonhereditary congenital deformity. Digital enlargement in macrodactyly involves all tissue types and presents alone or as part of a congenital deformity syndromes. Macrodactyly treatment largely depends on surgeons' experience and knowledge. Because there is a paucity of large cohort studies of macrodactyly in the literature, our goal was to retrospectively analyze macrodactyly cases in order to define a better system for diagnosis, classification, and prognosis. METHODS: Medical records of 90 Chinese macrodactyly patients, including demographic characteristics, clinical presentations, anatomical distributions, x-rays, pathological findings, and treatments, were reviewed. Genetic analyses of 12 patients were also reviewed. RESULTS: Disease incidence was similar across sex and geographical regions. Multiple-digit involvement was 2.6 times more frequent than single-digit involvement. The index finger, middle finger, and thumb were most commonly involved. Two digits were affected more often than 3, with the affected digits adjacent in most cases. The affected digit was in the median nerve innervation distribution in 79% of cases and was accompanied by enlargement and fat infiltration of the median nerve. Seven cases had syndactyly. Ten of the 12 cases subjected to PIK3CA mutation analysis were positive. CONCLUSIONS: Macrodactyly represents a heterogeneous group of conditions, without significant sex or geographical predilection, which is usually present at birth. A high PIK3CA mutation-positive rate in affected tissues suggests a similar cellular mechanism for overgrowth in patients with various clinical presentations. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

Trauma-induced Rejection in Vascularized Composite Allotransplantation.

: Vascularized composite allotransplantation (VCA) is a relatively new field in reconstructive medicine. Likely a result of the unique tissue composition of these allografts-including skin and often a bone marrow component-the immunology and rejection patterns do not always mimic those of the well-studied solid organ transplantations. While the number and type of VCAs performed is rapidly expanding, there is still much to be discovered and understood in the field. With more patients, new findings and patterns emerge and add to our understanding of VCA. Here, we present a case report of an upper extremity transplant recipient with trauma-induced rejection.

Characterization of Clinical and Histological Rejection of Male Genital Tissues Using a Novel Microsurgical Rat Penile Transplantation Model.

BACKGROUND: Penis transplantation represents an exciting new avenue for restoration of male urogenitalia. However, little is known about the specific immunological features of penile transplants, limiting their application in complex urogenital reconstruction. To properly study this emerging form of transplantation, adequate preclinical models are a necessity. The purpose of this study is to establish a clinical and histological rejection classification of urogenital tissue transplants using a new rat heterotopic penile transplant model that includes preputial skin. METHODS: Syngeneic and allogeneic heterotopic penile transplantations were performed on Lewis and Brown Norway rats using a new model designed by our group. Grafts were clinically and histologically monitored at postoperative days (POD) 3-30. RESULTS: Six syngeneic and 25 allogeneic transplants were performed. All syngeneic and tacrolimus-treated grafts survived until endpoint. Allogeneic graft rejection is shown to follow a 4-stage clinical progression with all untreated allografts developing epidermal sloughing at POD7 and full rejecting between POD14 and POD16. Histological samples were used to develop a specific 4-grade rejection classification analogous to the 2007 Banff Criteria for skin-containing allografts. CONCLUSIONS: Graft skin and urethral lining tissue are first rejection targets followed by tunica albuginea and corpora cavernosa in a distal to proximal pattern. We established a robust and reproducible murine model to study the immunobiology of male genital tissue in the context of transplantation and developed a novel 4-grade clinical and histological rejection scale based on graft skin and urethral lining as the main targets of rejection.

Poly(ε-Caprolactone) Nanofiber Wrap Improves Nerve Regeneration and Functional Outcomes after Delayed Nerve Repair.

BACKGROUND: The purpose of this study was to assess the efficacy of biodegradable, electrospun poly(ε-caprolactone) nanofiber nerve conduits in improving nerve regeneration. METHODS: The authors used a rat forelimb chronic denervation model to assess the effects of poly(ε-caprolactone) conduits on improving nerve regeneration and upper extremity function. Three groups of rats were examined: (1) negative-control animals (n = 5), which underwent 8 weeks of median nerve chronic denervation injury followed by repair with no conduit; (2) experimental animals (n = 5), which underwent 8 weeks of median nerve chronic denervation followed by repair and poly(ε-caprolactone) nerve conduit wrapping of the nerve coaptation site; and (3) positive-control animals (n = 5), which were naive controls. All animals underwent compound muscle action potential and functional testing. At 14 weeks after repair, the median nerve and flexor muscles were harvested for histologic analysis. RESULTS: Histomorphometric analysis of regenerating median nerves demonstrated augmented axonal regeneration in experimental versus negative control animals (total axon count, 1769 ± 672 versus 1072 ± 123.80; p = 0.0468). With regard to functional recovery, experimental and negative-control animals (1.67 ± 0.04 versus 0.97 ± 0.39; p = 0.036) had regained 34.9 percent and 25.4 percent, respectively, of baseline hand grip strength at 14 weeks after repair. Lastly, less collagen deposition at the nerve coaptation site of experimental animals was found when compared to control animals (p < 0.05). CONCLUSION: Biodegradable, poly(ε-caprolactone) nanofiber nerve conduits can improve nerve regeneration and subsequent physiologic extremity function in the setting of delayed nerve repair by decreasing the scar burden at nerve coaptation sites.

Glial Cell Line-Derived Neurotrophic Factor and Chondroitinase Promote Axonal Regeneration in a Chronic Denervation Animal Model.

Functional recovery following nerve injury declines when target re-innervation is delayed. Currently, no intervention exists to improve outcomes after prolonged denervation. We explored the neuroregenerative effects of glial cell line-derived neurotrophic factor (GDNF) and chondroitinase (CDN) in a chronic denervation animal model. A fibrin-based sustained delivery method for growth factors was optimized in vitro and in vivo, and then tested in our animal model. GDNF, CDN, and GDNF+CDN were injected into the denervated stump at the time of nerve repair. Histomorphometry and retrograde labeling were used to assess axonal regeneration. The mechanisms promoting such regeneration were explored with immunofluorescence. Five weeks after repair, the GDNF+CDN group had the highest number and maturity of axons. GDNF was noted to preferentially promote axonal maturity, whereas CDN predominantly increased the number of axons. GDNF favored motor neuron regeneration, and upregulated Ki67 in Schwann cells. CDN did not favor motor versus sensory regeneration and was noted to cleave inhibitory endoneurial proteoglycans. Early measures of nerve regeneration after delayed repair are improved by activating Schwann cells and breaking down the inhibitory proteoglycans in the distal nerve segment, suggesting a role for GDNF+CDN to be translated for human nerve repairs.

Prosthetic Rehabilitation and Vascularized Composite Allotransplantation following Upper Limb Loss.

BACKGROUND: Upper limb loss is a devastating condition with dramatic physical, psychological, financial, and social consequences. Improvements in the fields of prosthetics and vascularized composite allotransplantation have opened exciting new frontiers for treatment and rehabilitation following upper limb loss. Each modality offers a unique set of advantages and limitations with regard to the restoration of hand function following amputation. METHODS: Presented in this article is a discussion outlining the complex considerations and decisions encountered when determining patient appropriateness for either prosthetic rehabilitation or vascularized composite allotransplantation following upper limb loss. In this review, the authors examine how psychosocial factors, nature of injury, rehabilitation course, functional outcomes, and risks and benefits may affect overall patient selection for either rehabilitative approach. RESULTS: This review summarizes the current state of the literature. Advancements in both prosthetic and biological strategies demonstrate promise with regard to facilitating rehabilitation following upper limb loss. However, there remains a dearth of research directly comparing outcomes in prosthetic rehabilitation to that following upper extremity transplantation. CONCLUSIONS: Few studies have performed a direct comparison between patients undergoing vascularized composite allotransplantation and those undergoing prosthetic rehabilitation. Upper extremity transplantation and prosthetic reconstruction should not be viewed as competing options, but rather as two treatment modalities with different risk-to-benefit profiles and indications.

Growth Hormone Improves Nerve Regeneration, Muscle Re-innervation, and Functional Outcomes After Chronic Denervation Injury.

This study investigates the efficacy of systemic growth hormone (GH) therapy in ameliorating the deleterious effects of chronic denervation (CD) injury on nerve regeneration and resulting motor function. Using a forelimb CD model, 4 groups of Lewis rats were examined (n = 8 per group): Group-1 (negative control) 8 weeks of median nerve CD followed by ulnar-to-median nerve transfer; Group-2 (experimental) 8 weeks of median nerve CD followed by ulnar-to-median nerve transfer and highly purified lyophilized pituitary porcine GH treatment (0.6 mg/day); Group-3 (positive control) immediate ulnar-to-median nerve transfer without CD; Group-4 (baseline) naïve controls. All animals underwent weekly grip strength testing and were sacrificed 14 weeks following nerve transfer for histomorphometric analysis of median nerve regeneration, flexor digitorum superficialis atrophy, and neuromuscular junction reinnervation. In comparison to untreated controls, GH-treated animals demonstrated enhanced median nerve regeneration as measured by axon density (p < 0.005), axon diameter (p < 0.0001), and myelin thickness (p < 0.0001); improved muscle re-innervation (27.9% vs 38.0% NMJs re-innervated; p < 0.02); reduced muscle atrophy (1146 ± 93.19 µm2 vs 865.2 ± 48.33 µm2; p < 0.02); and greater recovery of motor function (grip strength: p < 0.001). These findings support the hypothesis that GH-therapy enhances axonal regeneration and maintains chronically-denervated muscle to thereby promote motor re-innervation and functional recovery.

Emerging Ethical Challenges Raised by the Evolution of Vascularized Composite Allotransplantation.

BACKGROUND: Despite early skepticism, the field of vascularized composite allotransplantation (VCA) has demonstrated feasibility. The ethics of VCA have moved past doubts about the morality of attempting such transplants to how to conduct them ethically. METHODS: Leaders of each program performing and/or evaluating VCA in the United States were invited to participate in a working group to assess the state and future of VCA ethics and policy. Four meetings were held over the course of 1 year to describe key challenges and potential solutions. RESULTS: Working group participants concluded that VCA holds great promise as treatment for patients with particular injuries or deficits, but the field faces unique challenges to adoption as standard of care, which can only be overcome by data sharing and standardization of evaluation and outcome metrics. CONCLUSIONS: Adequate attention must be given to concerns including managing the uniquely intense physician-patient relationship, ethical patient selection, ensuring patients have adequate representation, informing and earning the trust of the public for donation, standardizing metrics for success, and fostering an environment of data sharing. These steps are critical to transitioning VCA from research to standard of care and to its insurance coverage inclusion.

Muscle-derived stem cells: important players in peripheral nerve repair.

INTRODUCTION: Stem cell therapy for peripheral nerve repair is a rapidly evolving field in regenerative medicine. Although most studies to date have investigated stem cells originating from bone marrow or adipose, skeletal muscle has recently been recognized as an abundant and easily accessible source of stem cells. Muscle-derived stem cells (MDSCs) are a diverse population of multipotent cells with pronounced antioxidant and regenerative capacity. Areas covered: The current literature on the various roles MDSCs serve within the micro- and macro-environment of nerve injury. Furthermore, the exciting new research that is establishing MDSC-cellular therapy as an important therapeutic modality to improve peripheral nerve regeneration. Expert opinion: MDSCs are a promising therapeutic agent for the repair of peripheral nerves; MDSCs not only undergo gliogenesis and angiogenesis, but they also orchestrate larger pro-regenerative host responses. However, the isolation, transformation, and in-vivo behavior of MDSCs require further evaluation prior to clinical application.

The suppression effect of dendritic cells maturation by adipose-derived stem cells through TGF-ß1 related pathway.

BACKGROUND: Our previous studies demonstrated that adipose-derived stem cells (ASCs) could modulate regulatory T cells (Treg) and prolong hind-limb allotransplant survival in vitro and in vivo. Dendritic cells (DCs) play a pivotal role in innate and adaptive immunity. The aim of this study is to investigate the underlying mechanism of ASCs in modulating DC maturation. MATERIALS AND METHODS: ASCs were isolated from rodent adipose tissue, DCs were derived from the bone marrow, and CD4+ T cells were purified from splenocytes. DCs were co-cultured with ASCs to evaluate the suppressive effects of ASCs. CD4+ T-cells were co-cultured with DCs pre-treated with or without ASCs. The cell surface markers of DCs were analyzed by flow cytometry. T-cell proliferation was analyzed by the BrdU proliferation test. Tolerogenic cytokines and indoleamine 2,3-dioxygenase (IDO) expressions after different treatments were detected by quantitative real-time PCR, Western blotting, and ELISA analysis. RESULT: ASCs suppressed DC maturation as evidenced by low expressions of CD80, CD86, and MHC-II. Also, ASC-treated mature DCs showed higher levels of TGF-ß1, IL-10, and IDO expressions, as compared to that in matured DCs (mDCs) alone. ASC-treated mDCs co-cultured with CD4+ T cells revealed a significant higher percentage of Treg than mDC without treatment. The IDO level in ASC-treated mDCs and Treg induction effects were blocked by the ASCs pre-treated with TGF-ß1 siRNAs, but not IL-10 siRNAs. CONCLUSION: ASC-modulated DC maturation correlated with TGF-ß1 secretion, IDO expression, and Treg induction. ASCs could be used as a potential immunomodulatory strategy for clinical application in allotransplantation.

From Auto- to Allotransplantation: Immunomodulatory Protocol for Hand and Arm Transplantation.

AIM: To achieve a favorable risk-benefit balance for hand transplantation, an immunomodulatory protocol was developed in the laboratory and translated to clinical application. METHODS: Following donor bone marrow infusion into transplant recipients, hand and arm allografts have been maintained on low-dose tacrolimus monotherapy. RESULTS: Good-to-excellent functional recovery has been achieved in patients compliant with medication and therapy, thus restoring autonomous and productive lives. CONCLUSION: The risk-benefit balance can be tilted in favor of the hand transplant recipients by using an immunomodulatory protocol with minimum immunosuppression.