Current state of abdominal wall transplantation. Curr Opin Organ Transplant. 2017;21:159-164. [PMID: 26967839 DOI: 10.1097/mot.0000000000000276]

A local drug delivery system prolongs graft survival by dampening T cell infiltration and neutrophil extracellular trap formation in vascularized composite allografts

Introduction

The standard treatment for preventing rejection in vascularized composite allotransplantation (VCA) currently relies on systemic immunosuppression, which exposes the host to well-known side effects. Locally administered immunosuppression strategies have shown promising results to bypass this hurdle. Nevertheless, their progress has been slow, partially attributed to a limited understanding of the essential mechanisms underlying graft rejection. Recent discoveries highlight the crucial involvement of innate immune components, such as neutrophil extracellular traps (NETs), in organ transplantation. Here we aimed to prolong graft survival through a tacrolimus-based drug delivery system and to understand the role of NETs in VCA graft rejection.

Methods

To prevent off-target toxicity and promote graft survival, we tested a locally administered tacrolimus-loaded on-demand drug delivery system (TGMS-TAC) in a multiple MHC-mismatched porcine VCA model. Off-target toxicity was assessed in tissue and blood. Graft rejection was evaluated macroscopically while the complement system, T cells, neutrophils and NETs were analyzed in graft tissues by immunofluorescence and/or western blot. Plasmatic levels of inflammatory cytokines were measured using a Luminex magnetic-bead porcine panel, and NETs were measured in plasma and tissue using DNA-MPO ELISA. Lastly, to evaluate the effect of tacrolimus on NET formation, NETs were induced in-vitro in porcine and human peripheral neutrophils following incubation with tacrolimus.

Results

Repeated intra-graft administrations of TGMS-TAC minimized systemic toxicity and prolonged graft survival. Nevertheless, signs of rejection were observed at endpoint. Systemically, there were no increases in cytokine levels, complement anaphylatoxins, T-cell subpopulations, or neutrophils during rejection. Yet, tissue analysis showed local infiltration of T cells and neutrophils, together with neutrophil extracellular traps (NETs) in rejected grafts. Interestingly, intra-graft administration of tacrolimus contributed to a reduction in both T-cellular infiltration and NETs. In fact, in-vitro NETosis assessment showed a 62-84% reduction in NETs after stimulated neutrophils were treated with tacrolimus.

Conclusion

Our data indicate that the proposed local delivery of immunosuppression avoids off-target toxicity while prolonging graft survival in a multiple MHC-mismatch VCA model. Furthermore, NETs are found to play a role in graft rejection and could therefore be a potential innovative therapeutic target.

Acute Rejection Rates in Vascularized Composite Allografts: A Systematic Review of Case Reports

INTRODUCTION

Vascularized Composite Allografts (VCA) are usually performed in a full major histocompatibility complex mismatch setting, with a risk of acute rejection depending on factors such as the type of immunosuppression therapy and the quality of graft preservation. In this systematic review, we present the different immunosuppression protocols used in VCA and point out relationships between acute rejection rates and possible factors that might influence it.

METHODS

This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We systematically searched Medline (PubMed), Embase, and The Cochrane Library between November 2022 and February 2023, using following Mesh Terms: Transplant, Transplantation, Hand, Face, Uterus, Penis, Abdominal Wall, Larynx, and Composite Tissue Allografts. All VCA case reports and reviews describing multiple case reports were included.

RESULTS

We discovered 211 VCA cases reported. The preferred treatment was a combination of antithymocyte globulins, mycophenolate mofetil (MMF), tacrolimus, and steroids; and a combination of MMF, tacrolimus, and steroids for induction and maintenance treatment, respectively. Burn patients showed a higher acute rejection rate (P = 0.073) and were administered higher MMF doses (P = 0.020).

CONCLUSIONS

In contrast to previous statements, the field of VCA is not rapidly evolving, as it has encountered challenges in addressing immune-related concerns. This is highlighted by the absence of a standardized immunosuppression regimen. Consequently, more substantial data are required to draw more conclusive results regarding the immunogenicity of VCAs and the potential superiority of one immunosuppressive treatment over another. Future efforts should be made to report the VCA surgeries comprehensively, and muti-institutional long-term prospective follow-up studies should be performed to compare the number of acute rejections with influencing factors.

[Indications and results of intestinal transplantation for short bowel syndrome after mesenteric ischemia]

BACKGROUND

Intestinal transplantation (ITx) is the only causal treatment for complicated chronic intestinal failure after mesenteric ischemia and impending failure of parenteral supplementation. Isolated or combined ITx with the inclusion of the intestine is associated with demanding immunological, perioperative and infection associated challenges.

AIM

The characterization of chronic intestinal failure, the indications, transplant survival, transplantation techniques and success rates.

MATERIAL AND METHODS

Collection, summary and critical appraisal of international guidelines, the guidelines of the German Medical Chamber, and the international literature.

RESULTS

The first successful ITx were performed in 1987 and 1988 at the University of Kiel Germany and the University of Pittsburgh, USA. The number of ITx rose continuously but in phases from the end of the 1990s to over 200 per year but has currently decreased to 100-150 per year due to optimized intestinal rehabilitation. While the 1‑year and 3‑year transplant survival rates were 30% and 20% before 1991, they increased in phases up to 60% and 50%, respectively, after 1995 and have now achieved almost 80% and 70%, respectively.

CONCLUSION

The substantial improvement in the results of ITx can be partly explained by progress in operative techniques, intensive care medicine and a better understanding of mucosal immunity; however, optimized strategies in immunosuppression as well as prevention of infectious diseases and malignancies have also made decisive contributions.

Innovative surgical techniques in the intestine and multivisceral transplant

PURPOSE OF REVIEW

This timely review delves into the evolution of multivisceral transplantation (MVT) over the past six decades underscoring how advancements in surgical techniques and immunosuppression have driven transformation, to provide insight into the historical development of MVT, shedding light on its journey from experimentation to a valuable clinical approach.

RECENT FINDINGS

The review presents contemporary enhancements in surgical methods within the context of intestinal transplantation. The versatility of MVT is emphasized, accommodating diverse organ combinations and techniques. Both isolated intestinal transplantation (IIT) and MVT have seen expanded indications, driven by improved parenteral nutrition, transplantation outcomes, and surgical innovations. Surgical techniques are tailored based on graft type, with various approaches for isolated transplantation. Preservation strategies and ostomy techniques are also covered, along with graft assessment advancements involving donor-specific antibodies.

SUMMARY

This review's findings underscore the remarkable evolution of MVT from experimental origins to a comprehensive clinical practice. The progress in surgical techniques and immunosuppression has broadened the spectrum of patients who can benefit from intestinal transplant, including both IIT and MVT. The expansion of indications offers hope to patients with complex gastrointestinal disorders. The detection of donor-specific antibodies in graft assessment advances diagnostic accuracy, ultimately improving patient outcomes.

Pediatric intestine and multivisceral transplant

PURPOSE OF REVIEW

Intestinal and multivisceral transplantation (ITx, MVTx) is the cornerstone in treatment of irreversible intestinal failure (IF) and complications related to parenteral nutrition. This review aims to highlight the unique aspects of the subject in pediatrics.

RECENT FINDINGS

Etiology of intestinal failure (IF) in children shares some similarity with adults but several unique considerations when being evaluated for transplantation will be discussed. Owing to significant advancement in IF management and home parenteral nutrition (PN), indication criteria for pediatric transplantation continues to be updated. Outcomes have continued to improve with current long-term patient and graft survival in multicenter registry reports reported at 66.1% and 48.8% at 5 years, respectively. Pediatric specific surgical challenges such abdominal closure, post transplantation outcomes, and quality of life are discussed in this review.

SUMMARY

ITx and MVTx remain lifesaving treatment for many children with IF. However long-term graft function is still a major challenge.

First Report With Medium-term Follow-up of Intestinal Transplantation for Advanced and Recurrent Nonresectable Pseudomyxoma Peritonei

OBJECTIVE

To report our experience with the combination of radical surgical excision and intestinal transplantation in patients with recurrent pseudomyxoma peritonei (PMP) not amenable to further cytoreductive surgery (CRS).

BACKGROUND

CRS and heated intraoperative peritoneal chemotherapy are effective treatments for many patients with PMP. In patients with extensive small bowel involvement or nonresectable recurrence, disease progression results in small bowel obstruction, nutritional failure, and fistulation, with resulting abdominal wall failure.

METHODS

Between 2013 and 2022, patients with PMP who had a nutritional failure and were not suitable for further CRS underwent radical debulking and intestinal transplantation at our centre.

RESULTS

Fifteen patients underwent radical exenteration of affected intra-abdominal organs and transplantation adapted according to the individual case. Eight patients had isolated small bowel transplantation and 7 patients underwent modified multivisceral transplantation. In addition, in 7 patients with significant abdominal wall tumor involvement, a full-thickness vascularized abdominal wall transplant was performed. Two of the 15 patients died within 90 days due to surgically related complications. Actuarial 1-year and 5-year patient survivals were 79% and 55%, respectively. The majority of the patients had significant improvement in quality of life after transplantation. Progression/recurrence of disease was detected in 91% of patients followed up for more than 6 months.

CONCLUSION

Intestinal/multivisceral transplantation enables a more radical approach to the management of PMP than can be achieved with conventional surgical methods and is suitable for patients for whom there is no conventional surgical option. This complex surgical intervention requires the combined skills of both peritoneal malignancy and transplant teams.

Surgical Science and the Evolution of Critical Care Medicine

Surgical science has driven innovation and inquiry across adult and pediatric disciplines that provide critical care regardless of location. Surgically originated but broadly applicable knowledge has been globally shared within the pages Critical Care Medicine over the last 50 years.

Vacuum assisted closure for defects of the abdominal wall after intestinal transplantation

Background

Isolated intestinal transplantation (IT) is indicated in cases of intestinal failure (IF) in the absence of severe liver dysfunction. Short bowel syndrome (SBS) is the most frequent IF etiology, and due to the absence or considerable reduction of intestinal loops in the abdominal cavity in these patients, there is atrophy and muscle retraction of the abdominal wall, leading to loss of the abdominal domain and elasticity and preventing the primary closure of the abdominal wall. This study aimed to describe a technique for the closure of the abdominal wall after IT without using prostheses.

Methods

Four patients underwent IT with the impossibility of primary closure of the abdominal wall. We describe a novel technique, associating a series of vacuum-assisted closure dressings, components separation, and relaxation incisions.

Results

All patients presented a successful closure of the abdominal wall with the described technique, with no complications related to the abdominal wall.

Conclusion

The technique proved to be safe, effective, and reproducible as an option for abdominal wall closure after IT. Employing this technique in a greater number of cases is necessary to confirm these results.

Regenerative medicine technologies applied to transplant medicine.an update

Regenerative medicine (RM) is changing how we think and practice transplant medicine. In regenerative medicine, the aim is to develop and employ methods to regenerate, restore or replace damaged/diseased tissues or organs. Regenerative medicine investigates using tools such as novel technologies or techniques, extracellular vesicles, cell-based therapies, and tissue-engineered constructs to design effective patient-specific treatments. This review illustrates current advancements in regenerative medicine that may pertain to transplant medicine. We highlight progress made and various tools designed and employed specifically for each tissue or organ, such as the kidney, heart, liver, lung, vasculature, gastrointestinal tract, and pancreas. By combing both fields of transplant and regenerative medicine, we can harbor a successful collaboration that would be beneficial and efficacious for the repair and design of de novo engineered whole organs for transplantations.

New technique for abdominal wall procurement. Initial experience

Difficulty in obtaining adequate abdominal wall closure due to loss of the abdominal domain is a frequent complication of multivisceral, isolated intestinal transplantation and in some cases of liver transplantation. Various methods for primary closure have been proposed, including the use of synthetic and biological meshes, as well as full-thickness abdominal wall and non-vascularized rectus fascia grafts. We describe a novel technique for abdominal wall procurement in which the graft is perfused synchronously with the abdominal organs and can be transplanted as a full-thickness wall or as a non-vascularized rectus fascia graft. We performed six transplants of non-vascularized rectus fascia in three intestinal transplants, one multivisceral transplant, and two liver transplants. The size of the covered abdominal wall defects ranged from 17 cm × 7 cm to 25 cm × 20 cm. Only one patient developed graft infection secondary to enterocutaneous fistula requiring surgical correction and removal of the fascia graft. This patient, as well as two other patients, died due to sepsis. Our procurement technique allows removal of the rectus fascia graft to cover the abdominal wall defect, providing a feasible solution for treatment of abdominal wall defects in recipients after abdominal organ transplantation.

Using Radiographic Domain for Evaluating Indications in Abdominal Wall Transplantation

BACKGROUND

There is currently no description of abdominal domain changes in small bowel transplantation population or consensus of criteria regarding which patients are at high risk for immediate postoperative abdominal wall complications or would benefit from abdominal wall vascularized composite allotransplantation.

METHODS

A retrospective chart review was performed on 14 adult patients receiving intestinal or multivisceral transplantation. Preoperative and postoperative computed tomography scans were reviewed, and multiple variables were collected regarding abdominal domain and volume and analyzed comparing postoperative changes and abdominal wall complications.

RESULTS

Patients after intestinal or multivisceral transplantation had a mean reduction in overall intraperitoneal volume in the immediate postoperative period from 9031 cm3 to 7846 cm3 (P = 0.314). This intraperitoneal volume was further reduced to an average of 6261 cm3 upon radiographic evaluation greater than 1 year postoperatively (P = 0.024). Patients with preexisting abdominal wound (P = 0.002), radiation, or presence of ostomy (P = 0.047) were significantly associated with postoperative abdominal wall complications. No preoperative radiographic findings had a significant association with postoperative abdominal wall complications.

CONCLUSIONS

Computed tomography imaging demonstrates that intestinal and multivisceral transplant patients have significant reduction in intraperitoneal volume and domain after transplantation in the acute and delayed postoperative setting. Preoperative radiographic abdominal domain was not able to predict patients with postoperative abdominal wall complications. Patients with abdominal wounds, ostomies, and preoperative radiation therapy were associated with acute postoperative abdominal complications and may be considered for need of reconstructive techniques including abdominal wall transplantation.

Allotransplantation of donor rectus fascia for abdominal wall closure in transplant patients: A systematic review

BACKGROUND

Abdominal wall closure after intestinal, multivisceral or liver transplantation can be a major challenge. Different surgical techniques have been described to close complex abdominal wall defects, but results remain variable. Two promising transplant techniques have been developed using either non-vascularized or vascularized donor rectus fascia. This systematic review aimed to evaluate the feasibility, safety, and effectiveness of the two techniques.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Human studies published between January 2000 and April 2020 were included. Methodological quality appraisal was done using an adapted 10-item standardized checklist.

RESULTS

The search resulted in 9 articles including 74 patients. Both techniques proved to be feasible and had similar results. After non-vascularized rectus fascia allotransplantation, there was a slightly higher rate of surgical site infections in the earlier reports. Overall, there were few complications, no fascial graft related rejections or deaths. The included articles scored low on quality appraisal, mostly due to the small number of cases and scarcely reported outcome parameters.

CONCLUSIONS

This systematic literature review reports two emerging new techniques for complex abdominal wall closure in transplant patients, with promising results. Standardized data collection in a prospective manner could give us more detailed information about short- and long-term outcomes. Preclinical animal studies are necessary for a thorough investigation of the mechanisms of graft integration, the risk of hernia development and the alloimmune response against the graft.

Long-Term Outcomes of Abdominal Wall Reconstruction with Expanded Polytetrafluoroethylene Mesh in Pediatric Liver Transplantation

Background: Large-for-size syndrome caused by organ size mismatch increases the risk of abdominal compartment syndrome. Massive transfusion and portal vein clamping during liver transplantation may cause abdominal compartment syndrome (ACS) related to mesenteric congestion. In general pediatric surgery—such as correcting gastroschisis—abdominal wall reconstruction for the reparation of defects using expanded polytetrafluoroethylene is an established method. The purpose of this study is to describe the ePTFE-Gore-Tex closure method in patients with or at a high risk of ACS among pediatric liver transplant patients and to investigate the long-term prognosis and outcomes. Methods: From March 1988 to March 2018, 253 pediatric liver transplantation were performed in Seoul National University Hospital. We retrospectively reviewed the cases that underwent abdominal wall reconstruction with ePTFE during liver transplantation. Results: A total of 15 cases underwent abdominal closure with ePTFE-GoreTex graft. We usually used a 2 mm × 10 cm × 15 cm sized Gore-Tex graft for extending the abdominal cavity. The median follow up was 59.5 (17–128.7) months and there were no cases of ACS after transplantation. There were no infectious complications related to ePTFE implantation. The patient and graft survival rate during the study period was 93.3% (14/15). Conclusions: Abdominal wall reconstruction using ePTFE is feasible and could be an alternative option for patients with a high risk of ACS.

Biomarker and surrogate development in vascularised composite allograft transplantation: Current progress and future challenges

Vascularised composite allograft (VCA) transplantation is now a feasible reconstructive option for patients who have suffered significant soft tissue injuries. However, despite numerous technical advances in the field over two decades, a number of challenges remain, not least the management of transplant rejection. Part of the difficulty faced by clinicians is the early recognition and prevention of acute rejection episodes. Whilst this is potentially easier in VCAs than solid organ transplants, due to their visible skin component, at present the only validated method for the diagnosis of acute rejection is histological examination of a tissue biopsy. The aim of this review article is to provide an evidence-based overview of progress in the field of VCA biomarker discovery, including immune cell subsets, immune cell effector pathways, and circulating markers of allograft damage, and to discuss future challenges in the field.

Abdominal Wall Transplantation: Indications and Outcomes

Purpose of Review

This article aims to review published outcomes associated with full-thickness vascularized abdominal wall transplantation, with particular emphasis on advances in the field in the last 3 years.

Recent Findings

Forty-six full-thickness vascularized abdominal wall transplants have been performed in 44 patients worldwide. Approximately 35% of abdominal wall transplant recipients will experience at least one episode of acute rejection in the first year after transplant, compared with rejection rates of 87.8% and 72.7% for hand and face transplant respectively. Recent evidence suggests that combining a skin containing abdominal wall transplant with an intestinal transplant does not appear to increase sensitization or de novo donor-specific antibody formation.

Summary

Published data suggests that abdominal wall transplantation is an effective safe solution to achieve primary closure of the abdomen after intestinal or multivisceral transplant. However, better data is needed to confirm observations made and to determine long-term outcomes, requiring standardized data collection and reporting and collaboration between the small number of active transplant centres around the world.

Vascularised composite allotransplantation in solid organ transplant recipients: A systematic review

INTRODUCTION

A solid organ transplant (SOT) recipient, already taking immunosuppression, may represent the ideal candidate for vascularised composite allograft transplantation (VCA). However, concerns have been raised about the potential risk of SOT loss or the need for increased immunosuppression to sustain the VCA. This systematic review examines all published cases of SOT recipients who have received a VCA to establish associated morbidity and immunosuppression requirements.

METHODS

A systematic review was performed in accordance with the PRISMA guidelines. The PubMed, MEDLINE and EMBASE databases were searched for original articles published between January 1997 and May 2019. Only articles relating to patients who had received both a VCA and SOT with a reported follow up of greater than six months were included.

RESULTS

Fifteen articles were identified, including data from 39 VCAs in 37 patients. There was no increase in the number of SOT rejection episodes, complications such as post-transplant lymphoproliferative disorder or graft versus host disease, de novo donor specific HLA antibodies or short-term risks to the recipient when compared with SOT in isolation. One child required a sustained increase in their baseline immunosuppression following bilateral hand transplantation.

CONCLUSIONS

In this small heterogeneous cohort, the addition of a VCA to a SOT does not appear to increase the short-term risks to the SOT or the patient with comparable results to SOT in isolation. However, data are often poorly reported and longer-term follow up and uniform reporting of outcomes would be beneficial to more accurately assess the safety profile of combining VCA with SOT.

A Comparison of Immunosuppression Regimens in Hand, Face, and Kidney Transplantation

BACKGROUND

Authors have speculated that vascularized composite allotransplantation (VCA) recipients may require greater maintenance immunosuppression than solid organ transplant (SOT) recipients due to the higher antigenicity of skin. However, detailed comparisons of VCA and SOT immunosuppression regimens have been limited.

METHODS

Hand and face VCA recipient immunosuppression data were collected through a systematic literature review. Kidney recipient data were obtained through a retrospective chart review of the authors' institution. Prednisone and mycophenolate mofetil (MMF) doses were compared between VCA and kidney recipients at predefined follow-up intervals (<1, 1-5, and >5 y). Tacrolimus target trough levels (TTTL) were compared at follow-up intervals of 1-5 and >5 y, and stratified into our institution's kidney transplant risk-based target ranges (4-6 ng/mL, 6-8 ng/mL) or higher (>8 ng/mL).

RESULTS

Immunosuppression data were available for 57 VCA and 98 kidney recipients. There were no significant differences in prednisone doses between groups at all follow-up intervals. VCA recipient mean MMF dose was significantly greater at <1-y (1.71 ± 0.58 versus 1.16 ± 0.55 gm/d; P = 0.01). For VCA recipients, there was a significant difference (P = 0.02) in TTTL distribution over the three predefined therapeutic ranges (4-6 ng/mL, 6-8 ng/mL, and >8 ng/mL) between 1 and 5 y (24.0%, 20.0%, 56.0%, respectively) and >5 y (28.6%, 42.9%, 28.6%).

CONCLUSIONS

At longer follow-up, VCA and kidney recipients receive comparable MMF/prednisone doses, and most VCA recipients are treated with TTTL similar to kidney recipients. Further research may improve our understanding of VCA's complex risk/benefit ratio, and enhance informed consent.

Synchronous Abdominal Wall and Small-bowel Transplantation: A 1-year Follow-up

Abdominal wall-vascularized composite allotransplantation (AW-VCA) has evolved as a technically feasible but challenging option in the rare event of abdominal wall reconstruction in patients whose abdomen cannot be closed by applying conventional methods. The authors conducted the first synchronous child-to-adult recipient AW-VCA using an arteriovenous loop technique. This article presents a 1-year follow-up of the patient's postoperative course. Frequent skin biopsies were performed in accordance with Duke Institutional Review Board protocol, with 3 episodes of rejection treated with high-dose steroids and Thymoglobulin (Genzyme Corp, Cambridge, Mass.). The patient developed an opportunistic fungal brain abscess secondary to immunosuppression, which led to temporary upper extremity weakness. Future considerations for AW-VCA include a modified surgical technique involving utilization of donor vein graft for arteriovenous loop formation. In addition, reduction in postoperative biopsy schedule and changes in immunosuppression regimen may lead to improved outcomes and prevent unnecessary high-dose immunosuppression.

The histocompatibility and immunogenetics of hand transplantation

This short review will be concerned with the literature that has developed connected with the immunogenetic and tissue compatibility aspects of hand transplantation and will also draw on connected work in the more general area of vascularized composite allotransplantation (VCA) which includes face, abdominal wall uterus and larynx.

Indications of Intestinal Transplantation

"The intestinal transplantation is reserved for patients with life-threatening complications of permanent intestinal failure or underlying gastrointestinal disease. The choice of the allograft for a particular patient depends on several factors and the presence of concurrent organ failure, and availability of the donor organs, and specialized care. Combined liver and intestinal transplant allows for patients who have parenteral nutrition-associated liver disease a possibility of improved quality of life and nutrition as well as survival. Intestinal transplantation has made giant strides over the past few decades to the present era where current graft survivals are comparable with other solid organ transplants."

The difficult abdominal closure after paediatric intestinal transplantation: Use of abdominal rectus muscle fascia and literature review

Primary abdominal wall closure after intestinal and multivisceral transplantation may not be possible because of loss of abdominal domain and/or graft size/abdominal cavity mismatch. Traditional closure techniques for the open abdomen may not be valid in these circumstances because of severe scarring of the abdominal wall from multiple previous surgeries in this particular group of patients. We present our initial experience with the use of non-vascularized abdominal rectus muscle fascia in two patients who underwent deceased donation and living-related combined liver and small bowel transplantation, respectively, and who could not be closed primarily. The donor fascia was attached to the recipient fascia in both patients. In either case, there was not enough skin cover for closure, the wound was left open, and a negative pressure dressing was applied. In both cases, over a period of 6 months after placement of the non-vascularized abdominal rectus muscle fascia, the wound contracted, granulation tissue gradually covered the wound, and healing occurred, giving an intact abdominal wall. The abdominal rectus muscle fascia from a deceased donor can be used in a definite procedure for closure of the abdominal wall either at the time of transplant or later when a suitable rectus muscle fascia graft becomes available.

Small bowel and abdominal wall transplantation: A novel technique for synchronous revascularization

Abdominal wall transplantation (AWT) was introduced in 1999 in the context of reconstruction of complex abdominal wall defects in conjunction with visceral organ transplantation. As of recently, 38 cases of total AWT have been performed worldwide, about half of which were performed in the United States. While AWT is technically feasible, one of the major challenges presenting to the reconstructive surgeon is time to revascularization of the donor abdominal wall (AW), given the immediate proximity of the visceral organ and AWT. The authors report a novel AW revascularization technique during a synchronous small bowel and AWT in a 37-year-old man.

Current Status of Vascularized Composite Allotransplantation

The field of vascularized composite allotransplantation (VCA) has moved from a highly experimental procedure to, at least for some patients, one of the best treatment alternatives for catastrophic tissue loss or dysfunction. Although the worldwide experience is still limited, progress has been made in translation to the clinic, and hand transplantation was recently designated standard of care and is now covered in full by the British Health System. This progress is tempered by the long-term challenges of systemic immunosuppression, and the rapidly evolving indications for VCA such as urogenital transplantation. This update will cover the state of and recent changes in the field, and an update of the Louisville VCA program as our initial recipient, the first person to receive a hand transplant in the United States celebrates the 20th anniversary of his transplant. The achievements and complications encountered over the last two decades will be reviewed. In addition, potential directions for research and collaboration as well as practical issues of how third party payers and funding are affecting growth of the field are presented.

Graft vasculopathy of vascularized composite allografts in humans: a literature review and retrospective study

Mechanisms of chronic rejection of vascularized composite allografts (VCA) remain poorly understood and likely present along a spectrum of highly varied clinicopathological findings. Across both animal and human VCA however, graft vasculopathy (GV) has been the most consistent pathological finding resulting clinically in irreversible allograft dysfunction and eventual loss. A literature review of all reported clinical VCA cases with documented GV up to December 2018 was thus performed to elucidate the possible mechanisms involved. Relevant data extracted include C4d deposition, donor-specific antibody (DSA) formation, extent of human leukocyte antigen (HLA) mismatch, pretransplant panel reactive antibody levels, induction and maintenance immunosuppression used, the number of preceding acute rejection episodes, and time to histological confirmation of GV. Approximately 6% (13 of 205) of all VCA patients reported to date developed GV at a mean of 6 years post-transplantation. 46% of these patients have either lost or had their VCAs removed. Neither C4d nor DSA alone was predictive of GV development; however, when both are present, VCA loss appears inevitable due to progressive GV. Of utmost concern, GV in VCA does not appear to be abrogated by currently available immunosuppressive treatment and is essentially irreversible by the time of diagnosis with allograft loss a likely eventuality.

Abdominal wall transplantation in organ transplantation: Our experience

Abdominal wall transplantation has been consolidated as an alternative to primary abdominal wall closure in intestinal and multiple organ transplant recipients. Given that it is feasible to obtain the visceral graft and the abdominal wall graft from the same donor, abdominal wall transplantation could offer satisfactory outcomes and be easily coordinated. Non-vascularized fascia is one of the alternatives for abdominal wall closure in transplantation. We report two cases of non-vascularized fascia transplantation in intestinal and multivisceral transplants, respectively. Both donors were young (23 and 18 years old). Both recipients had endured multiple previous surgeries, and no surgical alternatives for primary wall repair could be offered. In both cases, a complete abdominal wall flap was retrieved from the donor, however, due to the characteristics of the recipient's abdominal wall defect, only non-vascularized fascia was used after removing skin and subcutaneous cellular tissue from the graft. Abdominal wall transplantation is an option to consider for abdominal wall closure in patients with multiple previous surgeries and no alternatives for primary wall repair.

Extrapolating novel techniques utilised in solid organ transplantation to the microsurgical and vascularised composite allograft arena

Ischemia reperfusion injury (IRI) is characterised initially by restriction of oxygenated blood flow to an organ bed, resulting in tissue hypoxia and ischaemic injury, followed by further 'reperfusion' injury upon restoration of perfusion, with an influx of oxygen, inflammatory cells and generation of free radicals. The culmination is a complex interplay between cellular and biochemical processes involved in inflammation and coagulation, exhibited as the 'no re-flow' phenomenon. Under ideal circumstances, autologous free tissue transfer is performed with short ischemic times. However, there are certain clinical scenarios where the ischaemic period can be prolonged due to technical and non-technical factors. IRI is inevitable and can be possibly more pronounced in such cases. In these cases, there may be a role for plastic surgeons to adopt some of the anti-ischaemia reperfusion injury (IRI) practices used in solid organ transplantation (SOT). Knowledge of the current trends in SOT IRI reduction should be discussed by plastic surgeons to assess whether certain facets can be extrapolated into the plastic and reconstructive armamentarium. These can be applicable to more challenging microsurgical cases, including composite free tissue transfer. Three important aspects are discussed further in this editorial: (1) cold flushing, (2) machine perfusion and pharmacological manipulation. Ongoing research will need to study the impact these potential interventions will have on the acute complications but also in which subset of patients they would be most beneficial. This area is novel and exciting but cautious implementation is advised with careful scrutiny of future data.

Abdominal Wall Transplant Surgery

The evolution and success of intestinal and multi-visceral transplantation over the past 20 years have raised the issue of difficult or even impossible abdominal closure, a topic rarely encountered in other fields of transplantation. Different techniques have been proposed to address this topic. The choice depends on the transplant team's expertise and/or the availability of a plastic surgery service. Abdominal wall transplant is a type of composite tissue allograft that can be utilized to reconstitute the abdominal domains of patients who undergo intestinal transplant, and the results are encouraging. It is an effective option to achieve primary abdominal closure after intestinal transplant. In its full-thickness form, it may be useful for monitoring rejection or viability of visceral organs. Our aim is to review the role of abdominal wall transplant in achieving tension-free closure of the abdomen.

Abdominal wall allotransplantation

Allotransplantation of vascularized composite tissue is a new field of transplantation surgery. One application of this technique is abdominal wall transplantation used as a supplementary procedure to the transplantation of visceral organs in patients with abdominal compartment deficits. As abdominal wall closure problems are experienced in around 30-40% of such patients, peer reviewed conclusions on the viability of various options, are important for an informed choice of possible procedures. This review focuses on the abdominal wall allotransplantion procedure. Our search provided 35 appropriate references which we used to support our findings as follows: abdominal wall transplantation was performed in 33 patients at seven centres. Of these, 30 had a full thickness abdominal wall transplanted from the same donor, 3 from a second donor. Three had visceral organ transplants and in addition, the posterior sheet of the rectus muscle fascia. In summary, our findings were that abdominal wall allotransplantation does not jeopardize the outcome of visceral organs transplantation. There is no higher risk of complications or rejection of the visceral organs. There have been no fatalities as a direct result of complications due to abdominal wall transplantation. Finally, the transplanted abdominal wall may provide an early warning of rejection before diagnostic tests on the bowel are symptomatic.

Innovations in reconstructive microsurgery: Reconstructive transplantation

In the past 20 years, reconstructive transplantation (RT) has emerged as a viable reconstructive option for carefully selected patients. More than 100 upper extremity and 40 face transplants have been performed worldwide to date. Concomitantly, the portfolio of reconstructive transplantation has been extended by additional procedures such as lower extremities, abdominal wall, neck, uterus, genitourinary, and pediatric transplants. In the present review article, we aim to summarize the current state of knowledge about this exciting field.

Squid Ring Teeth-coated Mesh Improves Abdominal Wall Repair

Background

Hernia repair is a common surgical procedure with polypropylene (PP) mesh being the standard material for correction because of its durability. However, complications such as seroma and pain are common, and repair failures still approach 15% secondary to poor tissue integration. In an effort to enhance mesh integration, we evaluated the applicability of a squid ring teeth (SRT) protein coating for soft-tissue repair in an abdominal wall defect model. SRT is a biologically derived high-strength protein with strong mechanical properties. We assessed tissue integration, strength, and biocompatibility of a SRT-coated PP mesh in a first-time pilot animal study.

Methods

PP mesh was coated with SRT (SRT-PP) and tested for mechanical strength against uncoated PP mesh. Cell proliferation and adhesion studies were performed in vitro using a 3T3 cell line. Rats underwent either PP (n = 3) or SRT-PP (n = 6) bridge mesh implantation in an anterior abdominal wall defect model. Repair was assessed clinically and radiographically, with integration evaluated by histology and mechanical testing at 60 days.

Results

Cell proliferation was enhanced on SRT-PP mesh. This was corroborated in vivo by abdominal wall histology, dramatically diminished craniocaudal mesh contraction, improved strength testing, and higher tissue failure strain. There was no increase in seroma or visceral adhesion formation. No foreign body reactions were noted on liver histology.

Conclusions

SRT applied as a coating appears to augment mesh-tissue integration and improve abdominal wall stability following bridged repair. Further studies in larger animals will determine its applicability for hernia repair in patients.

The abdominal wall transplant as a sentinel skin graft

PURPOSE OF REVIEW

Abdominal wall transplantation is a technique used to achieve abdominal closure after intestinal and multivisceral transplantation. This review focuses on whether there are additional benefits for the skin component as an immune-monitoring tool.

RECENT FINDINGS

The largest series of abdominal wall transplants has recently been published. Alongside the physiological advantage gained in abdominal closure, the authors describe the immunological insight that the skin component can provide and how this contributes to the management of patients. The skin appears to develop a rash with early rejection, which facilitates early systemic treatment before significant visceral rejection occurs. It can also help in cases in which there is diagnostic doubt regarding the cause of bowel dysfunction such as in instances of intestinal infection. Despite the additional immunological burden of donor tissue, there appears to be no requirement for increased immunosuppressive therapy.

SUMMARY

The technical and immunological feasibility of abdominal wall transplantation has now been demonstrated by several centres. Skin transplanted as part of the abdominal wall or as a separate vascularized sentinel skin flap may aid in the diagnosis of rejection. This has the potential to improve graft survival and reduce immunosuppressive morbidity.

Role of “reduced-size” liver/bowel grafts in the “abdominal wall transplantation” era

The evolution of multi-visceral and isolated intestinal transplant techniques over the last 3 decades has highlighted the technical challenges related to the closure of the abdomen at the end of the procedure. Two key factors that contribute to this challenge include: (1) Volume/edema of donor graft; and (2) loss of abdominal domain in the recipient. Not being able to close the abdominal wall leads to a variety of complications and morbidity that range from complex ventral hernias to bowel perforation. At the end of the 90’s this challenge was overcome by graft reduction during the donor operation or bench table procedure (especially reducing liver and small intestine), as well as techniques to increase the volume of abdominal cavity by pre-operative expansion devices. Recent reports from a few groups have demonstrated the ability of transplanting a full-thickness, vascularized abdominal wall from the same donor. Thus, a spectrum of techniques have co-evolved with multi-visceral and intestinal transplantation, ranging from graft reduction to enlarging the volume of the abdominal cavity. None of these techniques are free from complications, however in large-volume centers the combinations of both (graft reduction and abdominal widening, sometimes used in the same patient) could decrease the adverse events related to recipient’s closure, allowing a faster recovery. The quest for a solution to this unique challenge has led to the proposal and implementation of innovative solutions to enlarge the abdominal cavity.

Technology and vascularized composite allotransplantation (VCA)-lessons learned from the first bilateral pediatric hand transplant

The reconstructive principle of replacing "like with like" is best met with vascularized composite allotransplantation in which the components of an existing defect are "matched" to the greatest extent possible in a single stage restoration. Hand transplantation is a labor-intensive and time-intensive process and can be conceptualized into distinct phases that include (1) patient selection and preoperative preparation, (2) technical execution of the procedure, and (3) postoperative rehabilitation and follow-up. The advent of technological innovations, such as 3D printing technology, novel implant technology, as well as innovative imaging technology, such as functional magnetic resonance imaging have the potential of favorably affecting all phases of this process, thus contributing to improved outcomes. The use of these technologies in the world's first case of bilateral hand transplantation in a pediatric patient is discussed.