The 2020 Facial Transplantation Update: A 15-Year Compendium

Emerging Technologies

In this article, an array of new developments in burn care, from diagnosis to post-burn reconstruction and re-integration, will be discussed. Multidisciplinary advances have allowed the implementation of technologies that provide more accurate assessments of burn depth, improved outcomes when treating full-thickness burns, and enhanced scar tissue management. Incorporating these new treatment modalities into current practice is essential to improving the standard of burn care and developing the next generation of burn wound management methodologies.

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.

First-in-Human Whole-Eye Transplantation: Ensuring an Ethical Approach to Surgical Innovation

As innovations in the field of vascular composite allotransplantation (VCA) progress, whole-eye transplantation (WET) is poised to transition from non-human mammalian models to living human recipients. Present treatment options for vision loss are generally considered suboptimal, and attendant concerns ranging from aesthetics and prosthesis maintenance to social stigma may be mitigated by WET. Potential benefits to WET recipients may also include partial vision restoration, psychosocial benefits related to identity and social integration, improvements in physical comfort and function, and reduced surgical risk associated with a biologic eye compared to a prosthesis. Perioperative and postoperative risks of WET are expected to be comparable to those of facial transplantation (FT), and may be similarly mitigated by immunosuppressive protocols, adequate psychosocial support, and a thorough selection process for both the recipient and donor. To minimize the risks associated with immunosuppressive medications, the first attempts in human recipients will likely be performed in conjunction with a FT. If first-in-human attempts at combined FT-WET prove successful and the biologic eye survives, this opens the door for further advancement in the field of vision restoration by means of a viable surgical option. This analysis integrates recent innovations in WET research with the existing discourse on the ethics of surgical innovation and offers preliminary guidance to VCA programs considering undertaking WET in human recipients.

Immunologic Outcomes in Cross-Sex Solid Organ Transplants: A Systematic Review and Meta-Analysis to Inform Vascularized Composite Allotransplantation

BACKGROUND

Of nearly 90 hand and 50 face transplant recipients, only five have received a cross-sex vascularized composite allotransplantation (CS-VCA). CS-VCA has the potential to expand the donor pool and has been proven anatomically feasible and ethically acceptable in previous studies. However, there is a lack of immunologic data. This study evaluated the immunologic feasibility of CS-VCA through analysis of the solid organ transplant literature, given the paucity of CS-VCA data. The authors hypothesize that rates of acute rejection (AR) and graft survival (GS) in CS versus same-sex (SS) solid organ transplantation are similar.

METHODS

A systematic review and meta-analysis were performed. Studies comparing GS or AR episodes in CS and SS adult kidney (KT) and liver transplant (LT) populations were included. Odds ratios were calculated for overall GS and AR for all SS and CS transplant combinations [male-to-female (MTF), female-to-male, and overall].

RESULTS

A total of 693 articles were initially identified with 25 included in the meta-analysis. No significant difference in GS was noted between SS-KT versus CS-KT [OR, 1.04 (95% CI, 1.00 to 1.07); P = 0.07), SS-KT versus MTF-KT [OR, 0.97 (95% CI, 0.90 to 1.04); P = 0.41), and SS-LT versus MTF-LT [OR, 0.95 (95% CI, 0.91 to 1.00); P = 0.05). No significant difference in AR was noted between SS-KT versus MTF-KT [OR, 0.99 (95% CI, 0.96 to 1.02); P = 0.57), SS-LT versus CS-LT [OR, 0.78 (95% CI, 0.53 to 1.16); P = 0.22], or SS-LT versus female-to-male LT [OR, 1.03 (95% CI, 0.95 to 1.12); P = 0.47]. For the remaining pairings, GS was significantly increased and AR was significantly decreased in the SS transplants.

CONCLUSIONS

Published data suggest immunologic feasibility of CS-KT and CS-LT with the potential for generalization to the VCA population.

CLINICAL RELEVANCE STATEMENT

In theory, CS-VCA could expand the potential donor pool, ultimately leading to decreased wait times for recipients and improve the likelihood of establishing a immunologically favorable donor-recipient match.

Immunosuppressive strategies in face and hand transplantation: a comprehensive systematic review of current therapy regimens and outcomes

Background

Recipients of Vascularized Composite Allotransplants require effective immunosuppressive therapy to prevent graft rejection. This systematic review summarizes the current body of literature on immunosuppressive regimens used in face and hand transplants while summarizing their outcome in terms of rejection, renal failure, and infections.

Methods

A systematic search of electronic databases was conducted to identify relevant studies from 1998 until July 1st, 2023. We included all studies that discussed immunosuppressive strategies in face and hand transplant recipients according to PRISMA.

Results

The standard triple maintenance therapy was mostly adjusted due to nephrotoxicity or high incidence of rejection. The most common alternative treatments utilized were sirolimus (25/91; 27.5%) or everolimus (9/91; 9.9%) following hand- and photophoresis (7/45; 15.6%), sirolimus (5/45; 11.1%) or belatacept (1/45; 2.2%) following face transplantation. Episodes of rejection were reported in 60 (65.9%) of hand- and 33 (73%) of face transplant patients respectively. Graft loss of 12 (13.2%) hand and 4 (8.9%) face transplants was reported. Clinical CMV infection was observed in 6 (6.6%) hand and 7 (15.5%) face transplant recipients.

Conclusions

Based on the herein presented data, facial grafts exhibited a heightened incidence of rejection episodes and CMV infections. Facial mucosa adds complexity to the immunological graft composition highlighting the need of individualized immunosuppressive regimens and further research.

Review of two immunosuppressants: tacrolimus and cyclosporine

Immunosuppressants are vital in organ transplantation including facial transplantation (FT) but are associated with persistent side effects. This review article was prepared to compare the two most used immunosuppressants, cyclosporine and tacrolimus, in terms of mechanism of action, efficacy, and safety and to assess recent trials to mitigate their side effects. PubMed and Google Scholar queries were conducted using combinations of the following search terms: "transplantation immunosuppressant," "cyclosporine," "tacrolimus," "calcineurin inhibitor (CNI)," "efficacy," "safety," "induction therapy," "maintenance therapy," and "conversion therapy." Both immunosuppressants inhibit calcineurin and effectively down-regulate cytokines. Tacrolimus may be more advantageous since it lowers the likelihood of acute rejection, has the ability to reverse allograft rejection following cyclosporine treatment, and has the potential to reinnervate nerves. Meanwhile, graft survival rates seem to be comparable for the CNIs. To avoid nephrotoxicity, various immunosuppressants other than CNIs have been studied. Despite averting nephrotoxicity, these medications show increases in acute rejection or other types of adverse effects compared to CNIs. FT has been a topic of interest for oral and maxillofacial surgeons, and the postoperative usage of immunosuppressants is crucial for the long-term prognosis of FT. As contemporary transplantation regimens incorporate novel medications along with CNIs, further research is required.

Current opinion: advances in machine perfusion and preservation of vascularized composite allografts - will time still matter?

PURPOSE OF REVIEW

A major hurdle hindering more widespread application of reconstructive transplantation is the very limited cold ischemia time (CIT) of vascularized composite allografts (VCAs). In this review, we discuss cutting edge machine perfusion protocols and preservation strategies to overcome this limitation.

RECENT FINDINGS

Several preclinical machine perfusion studies have demonstrated the multifactorial utility of this technology to extend preservation windows, assess graft viability prior to transplantation and salvage damaged tissue, yet there are currently no clinically approved machine perfusion protocols for reconstructive transplantation. Thus, machine perfusion remains an open challenge in VCA due to the complexity of the various tissue types. In addition, multiple other promising avenues to prolong preservation of composite allografts have emerged. These include cryopreservation, high subzero preservation, vitrification and nanowarming. Despite several studies demonstrating extended preservation windows, there are several limitations that must be overcome prior to clinical translation. As both machine perfusion and subzero preservation protocols have rapidly advanced in the past few years, special consideration should be given to their potential complementary utilization.

SUMMARY

Current and emerging machine perfusion and preservation technologies in VCA have great promise to transform the field of reconstructive transplantation, as every extra hour of CIT helps ease the complexities of the peri-transplant workflow. Amongst the many advantages, longer preservation windows may allow for elective procedures, improved matching, establishment of novel immunomodulatory protocols and global transport of grafts, ultimately enabling us the ability to offer this life changing procedure to more patients.

Combined Face and Whole Eye Transplantation: Cadaveric Rehearsals and Feasibility Assessment

Background

In properly selected patients, combined face and whole eye transplantation (FWET) may offer a more optimal aesthetic and potentially functional outcome while avoiding the complications and stigma of enucleation and prosthetics. This study presents the most comprehensive cadaveric assessment for FWET to date, including rehearsal allograft procurement on a brain-dead donor.

Methods

Over a 2-year period, 15 rehearsal dissections were performed on 21 cadavers and one brain-dead donor. After identification of a potential recipient, rehearsals assessed clinical feasibility and enabled operative planning, technical practice, refinement of personalized equipment, and improved communication among team members. Operative techniques are described.

Results

Facial allograft procurement closely followed previously described face transplant techniques. Ophthalmic to superficial temporal (O-ST) vessel anastomosis for globe survival was assessed. Craniectomy allowed for maximal optic nerve and ophthalmic vessel pedicle length. Appropriate pedicle length and vessel caliber for O-ST anastomosis was seen. Research procurement demonstrated collateral blood flow to the orbit and surrounding structures from the external carotid system as well as confirmed the feasibility of timely O-ST anastomosis. Personalized cutting guides enabled highly accurate bony inset.

Conclusions

This study formalizes an approach to FWET, which is feasible for clinical translation in judiciously selected patients. O-ST anastomosis seems to minimize retinal ischemia time and allow perfusion of the combined allograft on a single external carotid pedicle. Although restoration of vision likely remains out of reach, globe survival is possible.

Application possibilities of artificial intelligence in facial vascularized composite allotransplantation-a narrative review

Facial vascularized composite allotransplantation (FVCA) is an emerging field of reconstructive surgery that represents a dogmatic shift in the surgical treatment of patients with severe facial disfigurements. While conventional reconstructive strategies were previously considered the goldstandard for patients with devastating facial trauma, FVCA has demonstrated promising short- and long-term outcomes. Yet, there remain several obstacles that complicate the integration of FVCA procedures into the standard workflow for facial trauma patients. Artificial intelligence (AI) has been shown to provide targeted and resource-effective solutions for persisting clinical challenges in various specialties. However, there is a paucity of studies elucidating the combination of FVCA and AI to overcome such hurdles. Here, we delineate the application possibilities of AI in the field of FVCA and discuss the use of AI technology for FVCA outcome simulation, diagnosis and prediction of rejection episodes, and malignancy screening. This line of research may serve as a fundament for future studies linking these two revolutionary biotechnologies.

Ensuring Racial and Ethnic Inclusivity in Facial Vascularized Composite Allotransplantation

Facial vascularized composite allotransplantation (fVCA) represents a valuable surgical option for reconstruction of the most devastating facial defects. There is a mounting body of evidence suggesting that healthcare disparities exist for a variety of other surgical and nonsurgical procedures. We aimed to investigate the potential existence of racial and ethnic disparities in the field of fVCA.

Methods

A comprehensive literature review was conducted by the authors of this review on PubMed/MEDLINE, and Embase databases from database inception to December 1, 2022 for studies published in the English and French languages. The search terms were (1) "face" OR "facial" AND (2) "transplant" OR "VCA" OR "vascularized composite allotransplantation" OR "vascularized composite allograft" OR "graft."

Results

Upon assessment of the racial and ethnic demographics of the 47 global cases of fVCA between 2005 and 2020, 36 were White, 10 were Asian, and one was Black. Sixteen of the 17 fVCA procedures performed in the United States involved White patients. The other patient self-identified as Black, equaling 6% of all US fVCA recipients.

Conclusion

Our analysis showed that the ethnic and racial distribution of fVCA has not proportionally reflected the racial and ethnic demographics of the general US population, underscoring the risk of such healthcare imbalances. Although large-scale studies are needed before drawing definitive conclusions, leaders in the field should take preventive steps to avoid potential disparities. Further investigations into the factors that facilitate or prohibit access to fVCA referral and surgery will be necessary moving forward.

Psychosocial and bioethical challenges and developments for the future of vascularized composite allotransplantation: A scoping review and viewpoint of recent developments and clinical experiences in the field of vascularized composite allotransplantation

Vascularized Composite Allotransplantation (VCA) has evolved in recent years, encompassing hand, face, uterus, penile, and lower extremity transplantation. Accordingly, without centralized oversight by United States Organ Procurement and Transplantation Network (OPTN) or European Programs, centers have developed their own practices and procedures that likely vary, and accordingly, present different levels of rigor to the evaluation process, internationally. The importance of psychosocial factors in the selection process and treatment course has been widely recognized, and therefore, several approaches have been developed to standardize and guide care of VCA candidates and recipients. We propose to develop an international multidisciplinary platform for the exchange of expertise that includes clinical, patient, and research perspectives. Patient perspectives would derive from peer education and the assessment of patient-reported outcomes. To establish a foundation for such a platform, future research should review and combine current VCA protocols, to develop the ethical framework for a standardized psychosocial evaluation and follow-up of VCA candidates and recipients. This review presents a comprehensive overview of recent results in the field of VCA, developments in structural aspects of VCA, and provides viewpoints driven from clinical experience.

Social support criteria in vascularized composite allotransplantation versus solid organ transplantation: Should the same ethical considerations apply?

The field of vascularized composite allotransplantation (VCA) is evolving, with some procedures poised to transition from highly experimental research toward standard of care. At present, the use of social support as an eligibility criterion for VCA candidacy is at the discretion of individual VCA programs, allowing VCA teams to consider the unique needs of each potential candidate. Yet this flexibility also creates potential for bias during the evaluation process which may disproportionately impact members of certain communities where social configurations may not resemble the model considered "optimal." We examine the extent to which ethical considerations for social support in solid organ transplantation (SOT) may be applied to or adapted for VCA, and the ethically meaningful ways in which VCA procedures differ from SOT. We conclude that VCA programs must retain some flexibility in determining criteria for candidacy at present; however, considerations of equity will become more pressing as VCA procedures evolve toward standard of care, and further empirical evidence will be needed to demonstrate the association between social support and post-operative success. The field of VCA has an opportunity to proactively address considerations of equity and justice and incorporate fair, inclusive practices into this innovative area of transplantation.

Face Transplant: Indications, Outcomes, and Ethical Issues-Where Do We Stand?

Background: The addition of face allotransplantation (FT) to the head and neck reconstructive surgery arsenal has started a true revolution. This study is aimed at providing an extensive analysis of the current practice of composite tissue allotransplantation. Moreover, a thorough description of pre-procedural, intra-operative, and post-procedural settings, indications, contraindications, outcomes, ethical considerations, and future perspectives is provided. Methods: The authors’ experience was supplemented with a literature review performed by using the PubMed, MEDLINE, and Embase databases on 21 February 2022. The search terms used were “face transplantation indications”, “face transplantation complications”, and “face transplantation ethical issues”. Results: The most recent achievements and long-term clinical sequelae of FT are classified and summarized. A large number of records (4435) were identified. Seventy-five articles were assessed for eligibility. Publications without new data and reports with a patient follow-up < 5 years were excluded. Nineteen articles met the criteria for inclusion. Conclusions: The most recent achievements in the field of FT may be combined with cutting-edge regenerative medicine procedures and innovative immunological processing. It is paramount to build strong international networks between the world FT experts in order to achieve higher-level outcomes and reduce the complication rate. Nevertheless, the utmost caution is required in patient selection, clinical assessment, strict follow-up, and rejection management.