Transplantation of the abdominal wall

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.

Could Sentinel Skin Transplants Have Some Utility in Solid Organ Transplantation?

Accurate diagnosis of allograft rejection can be hazardous and challenging. A strategy that has emerged from experience with vascularized composite allografts (VCAs) is the use of sentinel skin transplants (SSTs)-portions of donor skin transplanted synchronously to an allograft. Work in nonhuman animal models and experience with VCAs suggest concordance between rejection occurring in the primary allograft and the SST, and that appearance of rejection in the SST may precede rejection in the primary allograft, permitting early therapeutic intervention that may improve outcomes with lower rates of chronic rejection. The encouraging findings reported in VCA transplantation raise the possibility that SST may also be useful in solid organ transplantation. Some evidence is provided by experience with abdominal wall transplantation in some intestinal and multivisceral transplant recipients. Results from those reports raise the possibility that rejection may manifest in the skin component before emergence in the intestinal allograft, providing a "lead time" during which treatment of rejection of the abdominal wall could prevent the emergence of intestinal rejection. It is plausible that these findings may be extrapolated to other solid organ allografts, especially those for which obtaining an accurate diagnosis of acute rejection can be hazardous and challenging, such as the lung or pancreas. However, more data are required to support widespread adoption of this technique.

Intestinal transplantation: a review

PURPOSE OF REVIEW

The purpose of this article is to review the existing literature on the current indications, surgical techniques, immunosuppressive therapy and outcomes following intestinal transplantation (ITx).

RECENT FINDINGS

Over recent years, ITx has become a more common operation with approximately 2500 procedures carried out worldwide by 2014. It is reserved for patients with intestinal failure and who have developed complications of home parenteral nutrition or who have a high risk of dying from their underlying disease. Recent advances such as the improvement in survival rates, not only for isolated small bowel transplants but also following inclusion of a liver graft in combined liver-small bowel transplant, and the utility of citrulline as a noninvasive biomarker to appreciate acute rejection herald an exciting shift in the field of ITx.

SUMMARY

With advancements in immunosuppressive drugs, induction regimens, standardization of surgical techniques and improved postoperative care, survival is increasing. In due course, it will most likely become as good as remaining on home parenteral nutrition and as such could become a viable first-line option.

Current status of intestinal and multivisceral transplantation

Clinical-nutritional autonomy is the ultimate goal of patients with intestinal failure (IF). Traditionally, patients with IF have been relegated to lifelong parenteral nutrition (PN) once surgical and medical rehabilitation attempts at intestinal adaptation have failed. Over the past two decades, however, outcome improvements in intestinal transplantation have added another dimension to the therapeutic armamentarium in the field of gut rehabilitation. This has become possible through relentless efforts in the standardization of surgical techniques, advancements in immunosuppressive therapies and induction protocols and improvement in postoperative patient care. Four types of intestinal transplants include isolated small bowel transplant, liver-small bowel transplant, multivisceral transplant and modified multivisceral transplant. Current guidelines restrict intestinal transplantation to patients who have had significant complications from PN including liver failure and repeated infections. From an experimental stage to the currently established therapeutic modality for patients with advanced IF, outcome improvements have also been possible due to the introduction of tacrolimus in the early 1990s. Studies have shown that intestinal transplant is cost-effective within 1-3 years of graft survival compared with PN. Improved survival and quality of life as well as resumption of an oral diet should enable intestinal transplantation to be an important option for patients with IF in addition to continued rehabilitation. Future research should focus on detecting biomarkers of early rejection, enhanced immunosuppression protocols, improved postoperative care and early referral to transplant centers.

Noteworthy Literature Published in 2016 for Abdominal Organ Transplant Anesthesiologists

More than 400 peer-reviewed publications on the topic of pancreas transplantation, more than 400 on intestine transplantation, and more than 3000 on renal transplantation were published in 2016. This review will highlight the most pertinent literature for anesthesiologists caring for patients undergoing non-liver abdominal organ transplantation. This review is the second part in an annual series to review relevant contributions in the field of abdominal organ transplantation focusing on pancreas, intestine, and renal transplantation. We explore a myriad of topics, including outcomes determined by center size, novel assessment of intestine graft function, the effect of Zika virus on the transplant population, appropriate fluid management for renal transplantation, cardiovascular risk assessment in the transplant population, and several topics pertinent to optimizing patient and graft survival.

Long-Term Outcomes of Intestinal and Multivisceral Transplantation at a Single Center in Argentina

BACKGROUND

Intestinal failure (IF) patients received parenteral nutrition (PN) as the only available therapy until intestinal transplantation (ITx) evolved as an accepted treatment. The aim of this article is to report the long-term outcomes of a series of ITx performed in pediatric and adult patients at a single center 9 years after its creation.

PATIENTS AND METHODS

This is a retrospective analysis of the ITx performed between May 2006 and January 2015. Diagnoses, pre-ITx mean time on PN, indications for ITx, time on the waiting list for types of ITx, mean total ischemia time, and warm ischemia time, time until PN discontinuation, incidence of acute and chronic rejection, and 5-year actuarial patient survival are reported.

RESULTS

A total of 42 patients received ITx; 80% had short gut syndrome (SG); the mean time on PN was 1620 days. The main indication for ITx was lack of central venous access followed by intestinal failure-associated liver disease (IFALD) and catheter-related infectious complications. The mean time on the waiting list was 188 days (standard deviation, ±183 days). ITx were performed in 26 children and 14 adults. In all, 32 procedures were isolated ITx (IITX); 10 were multiorgan Tx (MOT; 3 combined, 7 multivisceral Tx (MVTx), 1 modified MVTx and 2 with kidney); 2 (4.7 %) were retransplantations: 1 IITx, 1 MVTx, and 5 including the right colon. Thirteen patients (31%) received abdominal rectus fascia. All procedures were performed by the same surgical team. Total ischemia time was 7:53 ± 2:04 hours, and warm ischemia time was 40.2 ± 10.5 minutes. The mean length of implanted intestine was 325 ± 63 cm. Bishop-Koop ileostomy was performed in 67% of cases. In all, 16 of 42 Tx required early reoperations. The overall mean follow-up time was 41 ± 35.6 months. The mean time to PN discontinuation after Tx was 68 days (P = .001). The total number of acute cellular rejection (ACR) episodes until the last follow-up was 83; the total number of grafts lost due to ACR was 4; and the total graft lost due to chronic rejection was 3. At the time of writing, the overall 5-year patient survival is 55% (65% for IITx vs 22% for MOT; P = .0001); 60% for pediatric recipients vs 47% for adults (P = NS); 64% when the indication for ITx was SG vs 25% for non-SG (P = .002).

CONCLUSIONS

At this center, candidates with SG, in the absence of IFALD requiring IITx, showed the best long-term outcomes, independent of recipient age. A multidisciplinary approach is mandatory for the care of intestinal failure patients, to sustain a rehabilitation and transplantation program over time.

Is There a Role for Living Donor Intestine Transplants?

The use of living donors with intestinal transplantation is controversial because it may not significantly improve candidate access to organs when intestine-only grafts are needed, and may involve excessive donor risk when combined liver-intestine grafts are required. Although limited data are available for comparison at this time, graft and patient survival rates for intestinal transplantations using living donors are no different than for deceased donor transplantations. Potential benefits that may be provided to the intestine transplant recipient through the use of living donors include better HLA matching, shorter ischemia times, better bowel preparation, and better opportunities for introducing immunomodulatory strategies. Conversely, living intestine donors are at risk for mortality, significant morbidity, financial loss, and psychologic trauma. The long-term outcomes of living intestine donors have not yet been reported. Ultimately, these data are essential before the wider use of living donors can be advocated for intestinal transplantation.

Abdominal wall regenerative medicine for a large defect using tissue engineering: an experimental study

PURPOSE

Treatment for a large abdominal wall defect remains challenging. The aim of this study was to optimize tissue engineering therapy of muscle constructs using a rat model.

METHODS

Experimental abdominal wall defects were created in Wister rats. The animal model was divided into three groups: collagen sponge (CS), hybrid scaffold (HS) and hybrid scaffold containing bone marrow liquid (HSBM). Hybrid scaffolds comprised collagen sponge and poly L-lactide (PLLA) sheets. Abdominal wall defects were covered by three kinds of sheets. Thereafter, the bone marrow liquid was spread onto the sheets. Rats were killed at 4, 8, and 16 weeks. Pathological examinations were performed using hematoxylin-eosin and desmin antibody staining.

RESULTS

The CS group showed abdominal hernia, whereas the HS and HSBM groups did not. Vascular formation was confirmed in all groups. Muscle tissue was recognized at the marginal area of the sheet only in the HSBM group.

CONCLUSION

The HS and HSBM groups show a greater intensity than the CS group. Muscle tissue regeneration is solely recognized in the HSBM group. Our experimental data suggest that the triad of scaffold, cell, and growth factor is fundamental for ideal biomaterials. The HSBM may be useful for reconstruction of abdominal wall defects.

Face transplant: long-term follow-up and results of a prospective open study

BACKGROUND

More than 30 face transplantations have been done worldwide since 2005 but no documented long-term follow-up has been reported in the literature. We aimed to answer remaining question about the long-term risks and benefits of face transplant.

METHODS

In this single-centre, prospective, open study, we assessed 20 patients presenting with facial defects. Ten patients were selected, and, after three were secondarily excluded, seven were transplanted: two with neurofibromatosis 1, one with a burn, and four with self-inflicted facial gunshot injuries. We report the long-term outcomes of six face allotransplant recipients at an average of 6 years (range 3·4-9 years) after the transplantation. All admissions to hospital except for planned revisions and immunosuppressive follow-up therapy were reported as adverse events (safety endpoint). Predefined immunological, metabolic, surgical, and social integration endpoints were collected prospectively. Patients underwent quantitative health-related quality of life assessments through Short Form 36 health questionnaires. This study was registered with ClinicalTrials.gov, number NCT00527280.

FINDINGS

Two of seven patients died: one at 65 days due to transplant destruction with concomitant pseudomonas infection and the second at 3·4 years after transplantation by suicide. The six patients alive at long-term follow-up presented with functional transplants. Safety endpoints were related to infection in the first month, acute rejection from 1 day to 7 years after transplantation, or side-effects of immunosuppressive therapy. Recurrent rejection episodes justified maintenance therapy with high-dose steroids at high levels in all patients at last follow-up, yet none of the patients developed diabetes. Three patients were found to have hypertension with one requiring therapy. All patients had a noticeable reduction in glomerular filtration rate. All recipients and their families accepted their transplant. Improvements in social integration and quality of life were highly variable among the patients and depended on baseline levels and psychiatric comorbidities.

INTERPRETATION

These long-term results show the crucial effect of patients' social support and pre-existing psychiatric conditions on the risk-benefit ratio of facial transplantation. Careful preoperative patient selection and long-term postoperative follow-up programmes under strict institutional review board controls should be used for any future grafts of this type.

FUNDING

Protocole Hospitalier de Recherche Clinique (PHRC) National.

Current state of abdominal wall transplantation

PURPOSE OF REVIEW

Primary closure of the abdominal wall remains one of the early challenges of intestinal transplantation. Our aim is to review the role of abdominal wall transplantation in achieving tension-free closure of the abdomen.

RECENT FINDINGS

In total, 38 full-thickness vascularized abdominal wall transplants, six partial-thickness vascularized and 17 partial-thickness nonvascularized rectus facia grafts have been reported worldwide. Different techniques have been described. The most popular choice seems to be the full-thickness vascularized abdominal wall allograft, where the anastomosis is performed either in a micro- or macrovascular fashion. Temporary 'remote' revascularisation of the allograft has been performed in some cases onto the recipient's forearm vessels when there is a long anticipated cold ischaemia time (>5 h). Preliminary data suggest that the abdominal wall skin rejection might be an early predictor of intestinal rejection. Vascularized and nonvascularized rectus fascia may be effective when there is inadequate healthy muscle/fascia but sufficient skin cover.

SUMMARY

Several centres have already proved the technical and immunologic feasibility of partial or full-thickness abdominal wall transplantation. It is an effective option to achieve primary abdominal closure following intestinal transplantation and in its full-thickness form, it may be useful for monitoring rejection in visceral organs.

Abdominal Wall Transplantation: Skin as a Sentinel Marker for Rejection

Abdominal wall transplantation (AWTX) has revolutionized difficult abdominal closure after intestinal transplantation (ITX). More important, the skin of the transplanted abdominal wall (AW) may serve as an immunological tool for differential diagnosis of bowel dysfunction after transplant. Between August 2008 and October 2014, 29 small bowel transplantations were performed in 28 patients (16 male, 12 female; aged 41 ± 13 years). Two groups were identified: the solid organ transplant (SOT) group (n = 15; 12 ITX and 3 modified multivisceral transplantation [MMVTX]) and the SOT-AWTX group (n = 14; 12 ITX and 2 MMVTX), with the latter including one ITX-AWTX retransplantation. Two doses of alemtuzumab were used for induction (30 mg, 6 and 24 h after reperfusion), and tacrolimus (trough levels 8-12 ng/mL) was used for maintenance immunosuppression. Patient survival was similar in both groups (67% vs. 61%); however, the SOT-AWTX group showed faster posttransplant recovery, better intestinal graft survival (79% vs. 60%), a lower intestinal rejection rate (7% vs. 27%) and a lower rate of misdiagnoses in which viral infection was mistaken and treated as rejection (14% vs. 33%). The skin component of the AW may serve as an immune modulator and sentinel marker for immunological activity in the host. This can be a vital tool for timely prevention of intestinal graft rejection and, more important, avoidance of overimmunosuppression in cases of bowel dysfunction not related to graft rejection.

Scleromatous Changes in an Abdominal Wall Graft: Graft-Versus-Graft Disease, or Chronic Graft Rejection?

Abdominal wall transplants are relatively new procedures that are frequently performed in conjunction with multivisceral transplants. The skin of the abdominal wall transplant is often the first site for graft rejection to manifest itself. Prompt recognition can lead to appropriate treatment before the involvement of the underlying viscera. However, the signs of graft rejection are nonspecific and can overlap with other entities. We present a case of a patient who received a multivisceral and abdominal wall transplant from 2 different donors, who presented with acute and eventually chronic graft rejection of the abdominal wall graft. Serial biopsies performed during the course of her treatment demonstrated progressive sclerotic changes in the dermis. Because these changes were confined to the abdominal wall graft, they could represent either chronic graft rejection or graft-versus-graft disease. To date, graft-versus-graft disease has not been documented in these patients. This case illustrates the possibility that patients with multidonor transplants may be at an increased risk for graft failure secondary to multiple potential etiologies.

Intestinal transplantation

Intestinal transplantation has now emerged as a lifesaving therapeutic option and standard of care for patients with irreversible intestinal failure. Improvement in survival over the years has justified expansion of the indications for intestinal transplantation beyond the original indications approved by Center for Medicare and Medicaid services. Management of patients with intestinal failure is complex and requires a multidisciplinary approach to accurately select candidates who would benefit from rehabilitation versus transplantation. Significant strides have been made in patient and graft survival with several advancements in the perioperative management through timely referral, improved patient selection, refinement in the surgical techniques and better understanding of the immunopathology of intestinal transplantation. The therapeutic efficacy of the procedure is well evident from continuous improvements in functional status, quality of life and cost-effectiveness of the procedure. This current review summarizes various aspects including current practices and evidence based recommendations of intestinal transplantation.

Orthotopic Hind Limb Transplantation in the Mouse

In vivo animal model systems, and in particular mouse models, have evolved into powerful and versatile scientific tools indispensable to basic and translational research in the field of transplantation medicine. A vast array of reagents is available exclusively in this setting, including mono- and polyclonal antibodies for both diagnostic and interventional applications. In addition, a vast number of genotyped, inbred, transgenic, and knock out strains allow detailed investigation of the individual contributions of humoral and cellular components to the complex interplay of an immune response and make the mouse the gold standard for immunological research. Vascularized Composite Allotransplantation (VCA) delineates a novel field of transplantation using allografts to replace "like with like" in patients suffering traumatic or congenital tissue loss. This surgical methodological protocol shows the use of a non-suture cuff technique for super-microvascular anastomosis in an orthotopic mouse hind limb transplantation model. The model specifically allows for comparison between established paradigms in solid organ transplantation with a novel form of transplants consisting of various different tissue components. Uniquely, this model allows for the transplantation of a viable vascularized bone marrow compartment and niche that have the potential to exert a beneficial effect on the balance of immune acceptance and rejection. This technique provides a tool to investigate alloantigen recognition and allograft rejection and acceptance, as well as enables the pursuit of functional nerve regeneration studies to further advance this novel field of transplantation.

Pediatric small bowel transplantation

PURPOSE OF REVIEW

Intestine has become a transplantable organ due to the improvement in immunosuppressive drugs. The early referral to a reference unit is crucial in prognosis. There are still some pending issues like chronic rejection, the knowledge of the role of DSA development or early noninvasive detection of acute rejection.

RECENT FINDINGS

The appearance of tacrolimus and mTOR, and the use of induction therapy have marked a turning point with better graft and patient survival rates. The inclusion of the liver in the graft seems to have a protective effect. Surveillance of opportunistic infections has also contributed to improved results. Infection, post-transplant lymphoproliferative disease, rejection and GVHD have still a major role in survival; however, antibody-mediated rejection has gained increased attention.

SUMMARY

Parenteral nutrition remains the main therapeutic resource in the management of intestinal failure, but intestinal transplant is a therapeutic option when this therapy has failed. Finding the balanced immunosuppression that minimizes risk of rejection while preventing occurrence of complications like post-transplant lymphoproliferative disease or GVHD is an ongoing challenge. The current survival rates of intestinal transplantation are similar to other solid organ transplant.

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.

Eculizumab Salvage Therapy for Antibody-Mediated Rejection in a Desensitization-Resistant Intestinal Re-Transplant Patient

The presence of elevated calculated panel reactive antibody (cPRA) and anti-HLA donor specific antibodies (DSA) are high risk factors for acute antibody-mediated rejection (AAMR) in intestinal transplantation that may lead to graft loss. Eculizumab has been used for the treatment of AAMR in kidney transplantation of sensitized patients that do not respond to other treatment. Here, we report a case where eculizumab was used to treat AAMR in a desensitization-resistant intestinal re-transplant patient. A male patient lost his intestinal graft to AAMR 8.14 years after his primary transplant. He received a second intestinal graft that had to be explanted a month later due to refractory AAMR. The patient remained highly sensitized despite multiple treatments. He received a multivisceral graft and presented with severe AAMR on day 3 posttransplantation. The AAMR was successfully treated with eculizumab. The patient presently maintains an elevated cPRA level above 90% but his DSAs have decreased from 18 000 MFI (mean fluorescent intensity) to below the positive cut-off value of 3000 MFI and remains rejection free with a 2-year follow-up since his multivisceral transplant. Eculizumab offers an alternative to treat AAMR in intestinal transplantation in desensitization-resistant patients.

Initial experience of dual maintenance immunosuppression with steroid withdrawal in vascular composite tissue allotransplantation

Current immunosuppression in VCA is largely based on the experience in solid organ transplantation. It remains unclear if steroids can be reduced safely in VCA recipients. We report on five VCA recipients who were weaned off maintenance steroids after a median of 2 months (mean: 4.8 months, range 2-12 months). Patients were kept subsequently on a low dose, dual maintenance consisting of tacrolimus and mycophenolate mofetil/mycophenloic acid with a mean follow-up of 43.6 months (median = 40 months, range 34-64 months). Early and late acute rejections responded well to temporarily augmented maintenance, topical immunosuppression, and/or steroid bolus treatment. One late steroid-resistant acute rejection required treatment with thymoglobulin. All patients have been gradually weaned off steroids subsequent to the treatment of acute rejections. Low levels of tacrolimus (<5 ng/mL) appeared as a risk for acute rejections. Although further experience and a cautious approach are warranted, dual-steroid free maintenance immunosuppression appears feasible in a series of five VCA recipients.

Spontaneous resolution of acute rejection and tolerance induction with IL-2 fusion protein in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) has emerged as a treatment option for treating nonlife-threatening conditions. Therefore, in order to make VCA a safe reconstruction option, there is a need to minimize immunosuppression, develop tolerance-inducing strategies and elucidate the mechanisms of VCA rejection and tolerance. In this study we explored the effects of hIL-2/Fc (a long-lasting human IL-2 fusion protein), in combination with antilymphocyte serum (ALS) and short-term cyclosporine A (CsA), on graft survival, regulatory T cell (Treg) proliferation and tolerance induction in a rat hind-limb transplant model. We demonstrate that hIL-2/Fc therapy tips the immune balance, increasing Treg proliferation and suppressing effector T cells, and permits VCA tolerance as demonstrated by long-term allograft survival and donor-antigen acceptance. Moreover, we observe two distinct types of acute rejection (AR), progressive and reversible, within hIL-2/Fc plus ALS and CsA treated recipients. Our study shows differential gene expression profiles of FoxP3 versus GzmB, Prf1 or interferon-γ in these two types of AR, with reversible rejection demonstrating higher Treg to Teff gene expression. This correlation of gene expression profile at the first clinical sign of AR with VCA outcomes can provide the basis for further inquiry into the mechanistic aspects of VCA rejection and future drug targets.

The concept of gut rehabilitation and the future of visceral transplantation

In the 1990s, the introduction of visceral transplantation fuelled interest in other innovative therapeutic modalities for gut rehabilitation. Ethanol lock and omega-3 lipid formulations were introduced to reduce the risks associated with total parenteral nutrition (TPN). Autologous surgical reconstruction and bowel lengthening have been increasingly utilized for patients with complex abdominal pathology and short-bowel syndrome. Glucagon-like peptide 2 analogue, along with growth hormone, are available to enhance gut adaptation and achieve nutritional autonomy. Intestinal transplantation continues to be limited to a rescue therapy for patients with TPN failure. Nonetheless, survival outcomes have substantially improved with advances in surgical techniques, immunosuppressive strategies and postoperative management. Furthermore, both nutritional autonomy and quality of life can be restored for more than two decades in most survivors, with social support and inclusion of the liver being favourable predictors of long-term outcome. One of the current challenges is the discovery of biomarkers to diagnose early rejection and further improve liver-free allograft survival. Currently, chronic rejection with persistence of preformed and development of de novo donor-specific antibodies is a major barrier to long-term graft function; this issue might be overcome with innovative immunological and tolerogenic strategies. This Review discusses advances in the field of gut rehabilitation, including intestinal transplantation, and highlights future challenges. With the growing interest in individualized medicine and the value of health care, a novel management algorithm is proposed to optimize patient care through an integrated multidisciplinary team approach.

Delayed dynamic abdominal wall closure following multi-visceral transplantation

INTRODUCTION

Primary closure of the abdominal wall following intestinal transplantation or multivisceral transplantation could become a challenging problem in a significant number of patients.

PRESENTATION OF CASE

A 38-year-old woman with familial adenomatous polyposis (FAP) underwent a multi-visceral transplantation for short gut syndrome. She subsequently developed acute graft rejection that proved resistant to conventional treatment. She was relisted and underwent re-transplantation along with kidney transplantation. Abdominal wall closure could not be achieved because of the large size of the graft and bowel oedema. The wound was initially managed with laparostomy followed by insertion of the delayed dynamic abdominal closure (DDAC) device (Abdominal Retraction Anchor – ABRA^® system). Continuous dynamic traction to the wound edges resulted in gradual approximation and complete closure of the abdominal wound was achieved within 3 weeks.

DISCUSSION

Successful abdominal closure after multivisceral transplantation or isolated intestinal transplantation often requires biological mesh, vascularised flaps or abdominal wall transplantation. DDAC eliminated the need for a prosthetic mesh or skin graft and provided an excellent cosmetic result. Adjustment of the dynamic traction at the bedside minimised the need for multiple returns to the operating theatre. It resulted in a well-healed linear scar without a hernia.

CONCLUSION

Dynamic traction allows delayed closure of laparotomy resulting in strong and cosmetically sound wound healing with native tissue.

A new rat model for orthotopic abdominal wall allotransplantation

Background:

Abdominal wall, one of the most commonly transplanted composite tissues, is less researched and lacking animal models. Its clinical necessities were emphasized in multiple case series to reconstruct large abdominal defects. Previous animal models have only studied components of the abdominal wall transplant. We describe findings from a new model that more likely reflect clinical transplantation.

Methods:

Full-thickness hemiabdominal wall flap was procured from Brown Norway (BN) rats and transplanted to an orthotopic defect on Lewis rats. Three groups were studied: group 1: Lewis to Lewis syngeneic; group 2: BN to Lewis control; and group 3: BN to Lewis with postoperative cyclosporine. Vascular imaging and cross vessel section were performed along with full-thickness abdominal wall. Immune cell profiling with flow cytometry at different time points was studied in all groups.

Results:

Syngeneic group had no rejection. Control group consistently showed rejection around postoperative day 6. With cyclosporine treatment, however, transplant and recipient tissue integration was observed. Flow cytometry revealed that innate immunity is responsible for the initial inflammatory events following abdominal wall engraftment. Adaptive immunity cells, specifically interferon-γ-producing T helper (Th) 1 and interleukin-17-producing Th17 cells, dramatically and positively correlate with rejection progression of abdominal wall transplants.

Conclusions:

Technical, histological, and immunological aspects of a new rat model are described. These results give clues to what occurs in human abdominal wall transplantation. In addition, Th1, a proinflammatory cell, was found to be a potential biomarker for allograft rejection.

Porcine acellular dermal matrix for delayed abdominal wall closure after pediatric liver transplantation

Children are one of the groups with the highest mortality rate on the waiting list for LT. Primary closure of the abdominal wall is often impossible in the pediatric population, due to a size mismatch between a large graft and a small recipient. We present a retrospective cohort study of six pediatric patients, who underwent delayed abdominal wall closure with a biological mesh after LT, and in whom early closure was impossible. A non-cross-linked porcine-derived acellular dermal matrix (Strattice(™) Reconstructive Tissue Matrix; LifeCell Corp, Bridgewater, NJ, USA) was used in all of the cases of the series. After a mean follow-up of 26 months (21-32 months), all patients were asymptomatic, with a functional abdominal wall after physical examination. Non-cross-linked porcine-derived acellular dermal matrix (Strattice(™) ) is a good alternative for delayed abdominal wall closure after pediatric LT. Randomized controlled trials are necessary to determine the best moment and the best technique for abdominal wall closure.

The current state of intestine transplantation: indications, techniques, outcomes and challenges

Intestine transplantation is the least common form of organ transplantation in the United States and often deemed one of the most difficult. Patient and graft survival have historically trailed well behind other organ transplants. Over the past 5-10 years registry reports and single center series have demonstrated improvements to patient survival after intestinal transplantation that now match patient survival for those without life-threatening complications on parenteral nutrition. For various reasons including improvements in medical care of patients with intestinal failure and difficulty accessing transplant care, the actual number of intestine transplants has declined by 25% over the past 6 years. In light of the small numbers of intestine transplants, many physicians and the lay public are often unaware that this is a therapeutic option. The aim of this review is to describe the current indications, outcomes and advances in the field of intestine transplantation and to explore concerns over future access to this important and life-saving therapy.

Engineering muscle constructs for the creation of functional engineered musculoskeletal tissue

Volumetric muscle loss (VML) is a disabling condition in which current clinical procedures are suboptimal. The field of tissue engineering has many promising strategies for the creation of functional skeletal muscle in vitro. However, there are still two key limitations that prevent it from becoming a solution for treating VML. First, engineered muscle tissue must be biocompatible to facilitate muscle tissue regrowth without generating an immune response. Second, engineered muscle constructs must be scaled up to facilitate replacement of clinically relevant volumes of tissue (centimeters in diameter). There are currently no tissue engineering strategies to produce tissue constructs that are both biocompatible and large enough to facilitate clinical repair. However, recent advances in tissue engineering using synthetic scaffolds, native scaffolds, or scaffold-free approaches may lead to a solution for repair of VML injuries.

Vascularized composite allotransplant in the realm of regenerative plastic surgery

Vascularized composite allotransplant (VCA) has led to new treatment options for patients with severe upper extremity and facial injuries. Although VCA can restore form and function, it exposes the patient to the risks associated with lifelong immunosuppression. Hopefully, ongoing advances in regenerative medicine will someday obviate the need for VCA, but until that time, VCA remains an immediate means of reconstructing otherwise unreconstructable defects. We review the outcomes of hand and face transplants, as well as the recent developments in immunosuppression as it relates to the field of VCA.

Stem cell-based organ replacements-airway and lung tissue engineering

Tissue engineering requires the use of cells seeded onto scaffolds, often in conjunction with bioactive molecules, to regenerate or replace tissues. Significant advances have been made in recent years within the fields of stem cell biology and biomaterials, leading to some exciting developments in airway tissue engineering, including the first use of stem cell-based tissue-engineered tracheal replacements in humans. In addition, recent advances within the fields of scaffold biology and decellularization offer the potential to transplant patients without the use of immunosuppression.

Remote revascularization of abdominal wall transplants using the forearm

Primary abdominal wall closure following small bowel transplantation is frequently impossible due to contraction of the abdominal domain. Although abdominal wall transplantation was reported 10 years ago this, technique has not been widely adopted, partly due to its complexity, but largely because of concerns that storing the abdominal allograft until the end of a prolonged intestinal transplant procedure would cause severe ischemia-reperfusion injury. We report six cases of combined small bowel and abdominal wall transplantation where the ischemic time was minimized by remotely revascularizing the abdominal wall on the forearm vessels, synchronous to the intestinal procedure. When the visceral transplant was complete, the abdominal wall was removed from the forearm and revascularized on the abdomen (n = 4), or used to close the abdomen while still vascularized on the forearm (n = 2). Primary abdominal wall closure was achieved in all. Mean cold ischemia was 305 min (300-330 min), and revascularization on the arm was 50 min (30-60 min). Three patients had proven abdominal wall rejection, all treated successfully. Immediate revascularization of the abdominal wall allograft substantially reduces cold ischemia without imposing constraints on the intestinal transplant. Reducing storage time may also have benefits with respect to ischemia-reperfusion-related graft immunogenicity.

Current status of vascularized composite tissue allotransplantation

Vascularized composite tissue allotransplantation (VCA) offers treatment options of complex functional deficiencies that cannot be repaired with conventional reconstructive methods. VCAs consist of blocks of functional units comprising different tissue types such as skin, bone, muscle, nerves, blood vessels, tendons, ligaments and others, and are thus substantially different from the composition of organ transplants. The field of VCA has made fascinating progresses in the recent past. Among other VCAs, numerous successful hand, face and limb transplants have been performed in the world. At the same time, specific questions in regard to innate and adaptive immunity, consequences of ischemia/reperfusion injury, immunosuppression, preservation, and regenerative capacity remain. In spite of this, the field is poised to make significant advances in the near future.

Niche Reconstructive Techniques for Complex Abdominal Wall Reconstruction: A Review

Abdominal wall defects resulting from recurrent hernias, trauma, and radiation necrosis are difficult and challenging to repair given the high rates of recurrence and surgical morbidity. Complex abdominal wall defects often require the transposition of autologous material to bridge the fascial gap. We present a review of niche reconstructive techniques that have been used in complex abdominal wall repair. The specific techniques reviewed include use of delayed and tunneled pedicled tensor fascia lata myofascial flap, de-epithelialized flap closure, free latissimus dorsi myocutaneous flap with or without innervation, and abdominal wall transplant. These niche surgical techniques have great potential to reduce recurrence rates when used in the proper setting for complex abdominal wall reconstruction. More studies are needed to evaluate the relative use of these techniques with the more widely established surgical methods of reconstruction.

Multivisceral (cluster) transplants, their spinoffs, and uterine transplants

In this presentation, we sought to update the information on cluster transplants and their spinoffs. In addition, we explain why we believe that uterine transplantation is a project worth pursuing as an option for women with uterine infertility.

Intestinal transplantation: review of operative techniques

The improvement of outcomes in intestinal transplantation (ITx) over the last two decades has been made possible through standardization in surgical techniques, improvements in immunosuppressive and induction protocols, and post-operative patient care. From a surgical technical point of view, all different types of small bowel containing transplants can be categorized into three main prototypes, including isolated small bowel, liver-small bowel, and multivisceral transplantations. In this review, we describe these three main prototypes and discuss the most important technical modifications of each type, as well as donor and recipient procedures, and highlight the more recent operative technical topics of discussion in the literature.

Vascularized composite allograft tolerance across MHC barriers in a large animal model

Vascularized composite allograft (VCA) transplantation can restore form and function following severe craniofacial injuries, extremity amputations or massive tissue loss. The induction of transplant tolerance would eliminate the need for long-term immunosuppression, realigning the risk-benefit ratio for these life-enhancing procedures. Skin, a critical component of VCA, has consistently presented the most stringent challenge to transplant tolerance. Here, we demonstrate, in a clinically relevant miniature swine model, induction of immunologic tolerance of VCAs across MHC barriers by induction of stable hematopoietic mixed chimerism. Recipient conditioning consisted of T cell depletion with CD3-immunotoxin, and 100 cGy total body irradiation prior to hematopoietic cell transplantation (HCT) and a 45-day course of cyclosporine A. VCA transplantation was performed either simultaneously to induction of mixed chimerism or into established mixed chimeras 85-150 days later. Following withdrawal of immunosuppression both VCAs transplanted into stable chimeras (n=4), and those transplanted at the time of HCT (n=2) accepted all components, including skin, without evidence of rejection to the experimental end point 115-504 days posttransplant. These data demonstrate that tolerance across MHC mismatches can be induced in a clinically relevant VCA model, providing proof of concept for long-term immunosuppression-free survival.

Intestinal transplantation: an unexpected journey. Robert E. Gross Lecture

The development of pediatric intestine transplantation has required continuous refinements in the management of intestinal failure, surgical technique, and perioperative care. The development of better immunosuppressive management (cyclosporine in 1978 and tacrolimus in 1989) and enhancements in our understanding of the relationship between recipient and host immune systems have resulted in better long-term survival. Paralleling this, advancements in the organ procurement techniques and organ preservation solutions have made possible the procurement and transplantation of various types of intestine containing grafts tailored to the needs of the various indications for which intestine transplantation is being performed. With improved outcomes, the indications for intestine transplantation have been better defined in the context of risk benefit for the most important complications of TPN, which include liver disease, life threatening infection, and loss of central venous access. The first survivors of transplantation would also go on to demonstrate the interaction (host-versus-graft and graft-versus-host) between recipient and donor immunocytes (brought with the allograft), which under the cover of immunosuppression allows varying degrees of graft acceptance. The struggle to achieve better transplantation survival outcomes came about with the development of improved strategies to better manage intestinal failure. This has been accomplished largely through the establishment of centers that incorporate a multidisciplinary team approach to medical and surgical care. Intestine transplantation represents a lifesaving therapy for many patients with intestinal failure who have significant complications of their disease. It is hoped that with the minimization of immunosuppression strategies currently used, the long-term survival of these intestine organ transplant recipients will continue improving, together with their rehabilitation and quality-of-life.

A critical analysis of rejection in vascularized composite allotransplantation: clinical, cellular and molecular aspects, current challenges, and novel concepts

Advances in microsurgical techniques and immunomodulatory protocols have contributed to the expansion of vascularized composite allotransplantation (VCA) with very encouraging immunological, functional, and cosmetic results. Rejection remains however a major hurdle that portends serious threats to recipients. Rejection features in VCA have been described in a number of studies, and an international consensus on the classification of rejection was established. Unfortunately, current available diagnostic methods carry many shortcomings that, in certain cases, pose a great diagnostic challenge to physicians especially in borderline rejection cases. In this review, we revisit the features of acute skin rejection in hand and face transplantation at the clinical, cellular, and molecular levels. The multiple challenges in diagnosing rejection and in defining chronic and antibody-mediated rejection in VCA are then presented, and we finish by analyzing current research directions and novel concepts aiming at improving available diagnostic measures.

Use of tissue expansion to facilitate liver and small bowel transplant in young children with contracted abdominal cavities

Liver and small bowel transplant is an established treatment for infants with IFALD. Despite organ reduction techniques, mortality on the waiting list remains high due to shortage of size-matched pediatric donors. Small abdominal cavity volume due to previous intestinal resection poses a significant challenge to achieve abdominal closure post-transplant. Seven children underwent tissue expansion of abdominal skin prior to multiorgan transplant. In total, 17 tissue expanders were placed subcutaneously in seven children. All seven subjects underwent re-exploration to deal with complications: hematoma, extrusion, infection, or port related. Three expanders had to be removed. Four children went on to have successful combined liver and small bowel transplant. Two children died on the waiting list of causes not related to the expander and one child died from sepsis attributed to an infected expander. Tissue expansion can generate skin to facilitate closure of abdomen post-transplant, thus allowing infants with small abdominal volumes to be considered for transplant surgery. Tissue expansion in children with end-stage liver disease and portal hypertension is associated with a very high complication rate and needs to be closely monitored during the expansion process.