Vascularized Composite Allotransplantation Research Articles

Partial Heterotopic Hindlimb Transplantation Model in Rats.

Vascularized composite allotransplantations (VCA) represent the most advanced reconstruction option for patients without autologous surgical possibilities after a complex tissue defect. Face and hand transplantations have changed disfigured patients' lives, giving them a new aesthetic and functional social organ. Despite promising outcomes, VCA is still underperformed due to life-long immunosuppression comorbidities and infectious complications. The rat is an ideal animal model for in vivo studies investigating immunological pathways and graft rejection mechanisms. Rats are also widely used in novel composite tissue graft preservation techniques, including perfusion and cryopreservation studies. Models used for VCA in rats must be reproducible, reliable, and efficient with low postoperative morbidity and mortality. Heterotopic limb transplantation procedures fulfill these criteria and are easier to perform than orthotopic limb transplants. Mastering rodent microsurgical models requires solid experience in microsurgery and animal care. Herein is reported a reliable and reproducible model of partial heterotopic osteomyocutaneous flap transplantation in rats, the postoperative outcomes, and the means of prevention of potential complications.

In Vivo Activity of Genetically Modified Cells Preseeded in Rat Vascularized Composite Allografts

Transplantation of the hand or face, known as vascularized composite allotransplantation (VCA), has revolutionized reconstructive surgery. Notwithstanding, there are still several areas of improvement to mitigate immune rejection while sparing systemic adverse effects. The goal of this study was to evaluate the engraftment and viability of a genetically modified cell population pre-engrafted into a VCA transplant, to potentially act as a local biosensor to report and modify the graft in vivo. A rat fibroblast cell line genetically modified to secrete Gaussia-Luciferase (gLuc), which served as a constitutive biomarker of cells, was incorporated into a VCA to study the viability of biosensor cells in a syngeneic rat heterotopic partial hindlimb transplantation model. Five perfusions were first performed as engineering runs to have a stable limb perfusion protocol, followed by 3 perfusions to analyze the cell engraftment during machine perfusion, and finally 4 perfusions to study in vivo persistence of the cell biosensors. Blood samples were collected to monitor gLuc secretion during perfusion and postoperatively. A time-dependent increase in gLuc secretion in the limb perfusion outflow during machine perfusion indirectly verified the presence of biosensors within the graft. After the ex vivo perfusion, VCA hindlimbs were analyzed for near infrared fluorescence emission that showed a presence of dyed engineered cells in all areas of the limbs. Postoperatively, gLuc was detectable 4 to 5 days after transplantation (W=16, P=.02857). This study demonstrated that engineered cells could be successfully preimplanted into VCAs-an important step toward development of an in vivo biosensor platform to use in modulating acute VCA outcomes.

The Effects of Tacrolimus on Tissue-Specific, Protein-Level Inflammatory Networks in Vascularized Composite Allotransplantation.

Systems-level insights into inflammatory events after vascularized composite allotransplantation (VCA) are critical to the success of immunomodulatory strategies of these complex procedures. To date, the effects of tacrolimus (TAC) immunosuppression on inflammatory networks in VCA, such as in acute rejection (AR), have not been investigated. We used a systems biology approach to elucidate the effects of tacrolimus on dynamic networks and principal drivers of systemic inflammation in the context of dynamic tissue-specific immune responses following VCA. Lewis (LEW) rat recipients received orthotopic hind limb VCA from fully major histocompatibility complex-mismatched Brown Norway (BN) donors or matched LEW donors. Group 1 (syngeneic controls) received LEW limbs without TAC, and Group 2 (treatment group) received BN limbs with TAC. Time-dependent changes in 27 inflammatory mediators were analyzed in skin, muscle, and peripheral blood using Principal Component Analysis (PCA), Dynamic Bayesian Network (DyBN) inference, and Dynamic Network Analysis (DyNA) to define principal characteristics, central nodes, and putative feedback structures of systemic inflammation. Analyses were repeated on skin + muscle data to construct a “Virtual VCA”, and in skin + muscle + peripheral blood data to construct a “Virtual Animal.” PCA, DyBN, and DyNA results from individual tissues suggested important roles for leptin, VEGF, various chemokines, the NLRP3 inflammasome (IL-1β, IL-18), and IL-6 after TAC treatment. The chemokines MCP-1, MIP-1α; and IP-10 were associated with AR in controls. Statistical analysis suggested that 24/27 inflammatory mediators were altered significantly between control and TAC-treated rats in peripheral blood, skin, and/or muscle over time. “Virtual VCA” and “Virtual Animal” analyses implicated the skin as a key control point of dynamic inflammatory networks, whose connectivity/complexity over time exhibited a U-shaped trajectory and was mirrored in the systemic circulation. Our study defines the effects of TAC on complex spatiotemporal evolution of dynamic inflammation networks in VCA. We also demonstrate the potential utility of computational analyses to elucidate nonlinear, cross-tissue interactions. These approaches may help define precision medicine approaches to better personalize TAC immunosuppression in VCA recipients.

Noninvasive evaluation of intragraft immune responses in upper extremity transplantation.

In vascularized composite allotransplantation (VCA), invasive tissue biopsies remain the gold standard in diagnosing rejection carrying significant morbidity. We aimed to show feasibility of tape-stripping for noninvasive immune monitoring in VCA. Tape-stripping was performed on allografts and native skin of upper extremity transplant recipients. Healthy nontransplanted individuals served as controls. The technique was also used in swine on naïve skin in nontransplanted animals, native skin of treated, transplanted swine, nonrejecting VCAs, and rejecting VCAs. Extracted protein was analyzed for differences in cytokine expression using Luminex technology. Significantly decreased levels of INFγ and IL-1Ra were seen between human allograft samples and native skin. In swine, rejecting grafts had increased IL-1Ra compared to naïve and native skin, decreased levels of GM-CSF compared to native skin, and decreased IL-10 compared to nonrejecting grafts. Unsupervised hierarchical clustering revealed rejecting grafts separated from the nonrejecting (P=0.021). Variable importance in projection scores identified GM-CSF, IL-1Ra, and IL-2 as the most important profiles for group discrimination. Differences in cytokine expression are detectable in human VCA patient native skin and VCA graft skin using a noninvasive tape-stripping method. Swine studies suggest that differences in cytokines between rejecting and nonrejecting grafts are discernable.

Perceived Success in Upper-Extremity Vascularized Composite Allotransplantation: A Qualitative Study

We performed a qualitative study to understand psychosocial factors associated with perceived success of upper-extremity vascularized composite allotransplantation (VCA). We interviewed transplant recipients and their primary caregivers. We recruited 4 upper-extremity VCA recipients and primary caregivers for 3 of them. We conducted semistructured face-to-face interviews using a guide that explored participants' transplantation experiences. Topics included comparison of pretransplant and posttransplant expectations, reflections on factors contributing to the success of the transplant experience, and posttransplant rehabilitation and functioning. We performed a thematic analysis that produced a list of themes, subthemes, and proposed hypotheses explaining how the themes related to the study's guiding questions. Participants described several factors as contributing to the success of the transplant experience, including developing realistic expectations about posttransplant function and lifelong immunosuppression, support from one's community and particularly the primary caregiver, and framing the experience in a positive light. Social, aesthetic, and other values unique to the hands, as opposed to prosthetics, motivated recipients to undergo VCA despite its inherent risk and uncertainties. Despite inherent challenges, undergoing VCA was viewed as worthwhile to regain benefits unique to hands. Participants met the challenges of the transplant process through setting realistic expectations, strong social support, and a positive perspective. Findings from this work may help clinicians and prospective patients to prepare for and set appropriate expectations of VCA.

High-resolution phenotyping of early acute rejection reveals a conserved alloimmune signature

Alloimmune responses in acute rejection are complex, involving multiple interacting cell types and pathways. Deep profiling of these cell types has been limited by technology that lacks the capacity to resolve this high dimensionality. Single-cell mass cytometry is used to characterize the alloimmune response in early acute rejection, measuring 37 parameters simultaneously, across multiple time points in two models: a murine cardiac and vascularized composite allotransplant (VCA). Semi-supervised hierarchical clustering is used to group related cell types defined by combinatorial expression of surface and intracellular proteins, along with markers of effector function and activation. This expression profile is mapped to visualize changes in antigen composition across cell types, revealing phenotypic signatures in alloimmune Tcells, natural killer (NK) cells, and myeloid subsets that are conserved and that firmly distinguish rejecting from non-rejecting grafts. These data provide a comprehensive, high-dimensional profile of cellular rejection after allograft transplantation.

Face transplantation: anesthesia and other organizational considerations.

In 2005, the first facial vascularized composite allotransplant was performed in France. In May 2018, our team at Maisonneuve-Rosemont Hospital, Montreal, Quebec, had the privilege to participate in the first facial transplant in Canada. Interdisciplinary collaboration, coordination, and communication formed the cornerstone of this medical undertaking and, ultimately, its success. This report details the anesthetic and organizational considerations of our experience.

Vascularized composite allotransplants as a mechanistic model for allograft rejection - an experimental study.

Vascularized composite allotransplants (VCAs) seem to have several unique features of clinical and experimental importance, including uniquely definable lymphatic drainage that can be easily accessed at the level of ipsilateral regional node beds. Thus, VCA offers a unique opportunity to assess the relative contribution of peripheral and secondary lymphoid tissue to the process of rejection. We transplanted hind limb grafts from C3H donors to six different groups of C57BL/6 recipients: Spleen+ Map3k14-/- ; Spleen- Map3k14-/- ; Spleen+ Node- Map3k14-/- ; and Spleen- Node- Map3k14-/- . As positive controls, we used Map3k14+/- with or without spleen. Map3k14+/- mice demonstrated an average graft survival of 9.6 and 9.2days for Spleen- and Spleen+ Map3k14+/- , respectively. Rejection in the Map3k14-/- group was considerably delayed (28.4days, P=0.002) in all recipients. The Spleen- Map3k14-/- mice rejected their hind limb allografts in an even more delayed fashion compared to Spleen+ Map3k14-/- (54.4days, P=0.02). Histological analysis of skin showed that acute rejection in both Map3k14+/- mice groups was graded as Banff III or Banff IV. In the Map3k14-/- groups, rejection was graded as Banff III. We demonstrated that in the absence of lymph nodes, grafts reject in a delayed fashion. Also, splenectomy in alymphoplastic mice further extends graft survival, but does not eliminate rejection all together.

The Effect of Narrow-Band Ultraviolet B Irradiation on the Vascularized Composite Allotransplantation Rat Model.

Vascularized composite allotransplantation (VCA) allows functional and esthetic reconstruction for patients with complex anatomical defects. However, acute and chronic graft rejections are significant obstacles to VCA. Ultraviolet light is an oncogenic environmental hazard. However, ultraviolet B (UVB) has an immunomodulation effect. Therefore, this study aims to elucidate the impact of UVB irradiation on the VCA rat model. The rat vascularized bone marrow allotransplantation model was used. A vascularized bone marrow from a Brown Norway rat (RT1Ac) was transplanted into a Lewis rat (RT1Ab). The allograft and surrounding abdominal skin were exposed to narrow-band ultraviolet B (NB-UVB) (311 nm) radiation with an energy of 1350 mJ/cm2 3 times a week until the end of the study period. There were 5 study groups: syngeneic transplantation (group 1), allogeneic transplantation (group 2), allogenic transplantation-NB-UVB (group 3), allogenic transplantation-antilymphocyte serum (ALS)-tacrolimus (group 4), and allogenic transplantation-antilymphocyte serum-tacrolimus-NB-UVB (group 5). Group 5 had decreased graft survival compared with group 4. In the donor cell chimerism analysis, donor cell chimerism decreased significantly after UVB irradiation and was unresponsive to the administered immunosuppressants. After UVB irradiation, the CD8 T-cell ratio was increased, and the regulatory T-cell ratio was decreased. The preliminary data showed that NB-UVB irradiation of the VCA rat model may decrease graft survival. However, further studies are needed to elucidate the possible mechanisms of this phenomenon.

Adipose-derived cellular therapies prolong graft survival in an allogenic hind limb transplantation model

BackgroundThe long-term survival after vascularized composite allotransplantation (VCA) is often limited by systemic rejection as well as the adverse effects of immunosuppressants. The stromal vascular fraction (SVF) can be expanded to produce adipose-derived stem cells (ADSC) which represents a combination of endothelial cells, preadipocytes, immune cells, and ADSC. It has been demonstrated that ADSC possess consistently reliable clinical results. However, literature is scarce regarding SVF in VCA. This study seeks to determine the impact of ex vivo allograft pretreatment in combination with SVF cells in the ability to promote composite tissue allotransplantation immunotolerance.MethodsA rat hind limb allotransplant model was used to investigate the influence of ex vivo pretreatment of SVF and ADSC on VCA survival. Intravascular cell-free saline, ADSC, or SVF was infused into the models with immunosuppressants. The histopathological examination and duration that the allografts went without displaying symptoms of rejection was documented. Peripheral T lymphocytes and Tregs were quantified with flow cytometry while allotissue expressions of CD31 were quantified with immunohistochemical staining (IHC). ELISA was used to detect vascular endothelial growth factor (VEGF)-A as well as anti- and pro-inflammatory cytokines.ResultsWe demonstrated that ex vivo treatment of allografts with SVF or ADSC prolonged allograft survival in contrast to medium control cohorts. There were also enhanced levels of immunomodulatory cytokines and increased VEGF-A and CD31 expression as well as reduced infiltration and proliferation of T lymphocytes along with raised Treg expressions.ConclusionThese studies demonstrated that adipose-derived cellular therapies prolong graft survival in an allogenic hind limb transplantation model and have the potential to establish immunotolerance.

Exosomes from donor-derived adipose mesenchymal stem cells prolong the survival of vascularized composite allografts.

Donor-derived adipose-derived mesenchymal stem cells (ADMSCs) dampen the alloimmune response and exosomes are reported to have biological activity similar to their parent cells. Here, we investigated the roles of exosomes from donor-derived ADMSCs (ADMSC-exo) in vascularized composite allotransplantation (VCA). Brown Norway-to-Lewis rat hindlimb transplantations were intravenously treated with either exosome from donor-derived ADMSCs or phosphate-buffered saline, combined with a short course of immunosuppression. We established that the treatment with ADMSC-exo prolongs the survival time of VCA grafts. Skin and muscle samples from ADMSC-exo-treated animals showed no histological signs of rejection, but samples from controls showed rejection of degree III. Comparing to the control group, a significant increase of donor cell chimerism, Tr1 and Treg, while a decrease of CD4+ T and Th1 cells were observed in the ADMSC-exo-treated group. Our findings imply that ADMSC-exo may be a valuable and safe treatment for extending VCA graft survival.

Immunosuppressive effect of mitomycin C-treated peripheral mononuclear blood cells (MICs) in vascularised composite allotransplantation

Vascularized Composite Allotransplantation (VCA) enables the restoration of complex tissue defects. Since the first successful hand and face transplants were performed, clinical and experimental research has consistently improved immunosuppressive therapies. The incubation of peripheral blood mononuclear cells (PBMCs) with mitomycin C (MMC) results in immunomodulatory cells (MICs). In previous studies, the systemic application of MICs on the day of allogeneic hind limb transplantation led to a significant immunosuppression in rats. The aim of this study is to further investigate the optimal point in time of MIC application in a complex VCA model. In six groups, 60 allogeneic hind limb transplantations were performed. Fully mismatched rats were used as hind limb donors [Lewis (LEW)] and recipients [Brown-Norway (BN)]. Group A received donor-derived MICs seven days preoperatively. Group B received no immunosuppression; group C received untreated PBMCs seven days prior to transplantation. Animals in group D received cell culture media, whereas group E was treated with a standard immunosuppression consisting of tacrolimus and prednisolone. In group F, syngeneic hind limb transplantations (BN→BN) were performed. Transplant rejection was assessed clinically and histologically. Group A showed a significantly earlier onset of allograft rejection after 3.5 ± 0.2 days (p < 0.01) when compared with control groups B, C and D (5.5 ± 0.7, 5.3 ± 0.7 und 5.7 ± 0.5). Groups E and F showedno allograft rejection. This study shows that the time of application determines the immunomodulatory effects of MICs. Whereas the systemic application of MICs on the day of transplantation led to a significant immunosuppression in previous studies, this study demonstrates that preoperative injections of MICs lead to an acceleration of allotransplant rejection. Follow-up studies are necessary to investigate further modifications of application time as well as dose-effect relations and cell characteristics of these potential immunosuppressive cells.

More than skin deep: Mucosal pathology in facial vascularized composite allografts. Commentary on “Pathologies of oral and sinonasal mucosa following facial vascularized composite allotransplantation”

The susceptibility of transplanted mucosa to rejection has been recognized since early in the facial vascularized composite allotransplantation experience (fVCA),1 but the appreciation of mucosal pathologies following face transplantation and the understanding of the pathophysiology and clinical importance of mucosal lesions remain secondary to those of skin.

Pathologies of oral and sinonasal mucosa following facial vascularized composite allotransplantation

Cutaneous changes of facial vascularized composite allotransplants (fVCAs) are extensively described in the literature. Parts of the nose, nasal, and oral cavities are included in most fVCAs. Distinctively, the nose and mouth are lined by mucosa. Little is known about the histopathology and complications of the mucosa involved in fVCA patients. The study constitutes a retrospective cohort study of nine fVCA patients. Medical records were reviewed for information about changes of oral and nasal mucous membranes. Types of mucosal lesions were recorded and analyzed. Uni- and multivariate generalized estimating equation (GEE) models were used to assess the odds of developing mucosal inflammation in the presence of clinico-pathologic variables. A total of 186 clinical encounters with examination of oral and nasal mucous membranes were included. Membranes were devoid of clinical pathology in 101 instances (53% of all clinical assessments). Ulcerations/erosions (27%), edema (18%), and erythema (14%) were the most common lesions. Oral lesions affected the lips (58%), buccal mucosa (38%), and palate (5%). Sinonasal processes predominantly affected nasal vestibules and septae. In univariate analysis, sirolimus, skin rejection, and skin Banff grade were associated with the presence of an acute inflammatory mucosal lesion (p<0.05). In multivariate analysis, skin Banff grade and sirolimus were independent predictors of mucosal inflammation. Pathologies of fVCA mucous membranes are more common than previously reported. Mucosal assessment plays an important role in the pleomorphic allograft rejection process evaluation rather than diagnosis and treatment based on cutaneous pathology. A closer look at the pathophysiology of fVCA mucosal rejection and inflammation is warranted.

Public Perceptions of Cross-Sex Vascularized Composite Allotransplantation

Cross-sex vascularized composite allotransplantation has been performed in cadaveric facial transplantation and clinical extremity transplantation. Understanding the challenge of appropriate donor-recipient matching, this study sought to characterize the public's perception of cross-sex vascularized composite allotransplantation. Participants were surveyed in New York City. Data collected included demographics and willingness to donate vascularized composite allografts (VCAs) of various types. Similar questions were asked in the context of same-sex and cross-sex donation. A total of 101 participants (male: 56.4%; age ≤35 years: 62.4%) were surveyed. The majority expressed willingness to donate to recipients of a different sex (hand: 78.2%, face: 56.4%, penis or uterus: 69.3%, lower limb: 81.2%, abdominal wall: 80.2%, larynx: 81.2%, and solid organs: 85.2%). Among VCAs, willingness to donate facial allografts was significantly different in same-sex versus cross-sex contexts (64.4% vs 56.4%; P = 0.008). Participants were also significantly more likely to donate VCAs to same-sex recipients on behalf of themselves versus loved ones (P < 0.05). There was significantly lower willingness to receive cross-sex versus same-sex facial (P = 0.022) and genital allografts (P = 0.022). Education on the preservation of recipient masculinity or femininity in cross-sex facial transplantation increased participants' willingness to receive a cross-sex face transplant from 56.4% to 71.3% (P = 0.001). This study highlights the urban public's acceptance of VCA donation or reception regardless of sex mismatch. There is increased willingness to receive a cross-sex face transplant after education, highlighting opportunities for future focused interventions to increase public awareness and ultimately the donor pool.

Unraveling the Crucial Roles of FoxP3+ Regulatory T Cells in Vascularized Composite Allograft Tolerance Induction and Maintenance.

The role of regulatory T cells (Treg) in tolerance induction of vascularized composite allotransplantation (VCA) remains unclear. This study was designed to examine characteristics of Treg after VCA and their capacity to rescue allografts from rejection. Osteomyocutaneous allografts were transplanted from Balb/c to C57BL/6 mice. All mice received costimulatory blockade and a short course of rapamycin. To elucidate the role of Treg for tolerance induction, Treg depletion was performed at postoperative day (POD) 0, 30, or 90. To assess capacity of Treg to rescue allografts from rejection, an injection of 2 × 106 Treg isolated from tolerant mice was applied. Eighty percent of VCA recipient mice using costimulatory blockade and rapamycin regimen developed tolerance. The tolerant recipients had a higher ratio of circulating Treg to effector T cells and elevated interleukin-10 at POD 30. A significantly higher rejection rate was observed when Treg were depleted at POD 30. But Treg depletion at POD 90 had no effect on tolerance. Treg from tolerant recipients showed stronger suppressive potential and the ability to rescue allografts from rejection. Furthermore, transplanted Treg-containing skin grafts from tolerant mice delayed rejection elicited by adoptively transferred effector T cells to Rag2-/- mice. Circulating Treg are crucial for inducing VCA tolerance in the early posttransplant phase, and allograft-residing Treg may maintain tolerance. Treg may, therefore, serve as a potential cellular therapeutic to improve VCA outcomes.

Pediatric Upper Extremity Vascularized Composite Allotransplantation—Progress and Future

Since 1998, over 120 upper extremity transplants have been successfully performed around the world; however, the field of vascularized composite allotransplantation (VCA) continues to face various medical challenges and ethical controversies. This article summarizes the worldwide experience with transplantation of vascularized composite upper extremities in children and discusses the unique considerations facing potential pediatric VCA recipients. Three children have successfully received composite upper or lower extremity transplants, of which two involved isografts and one involved allografts. Numerous research and clinical advances relevant to VCA have been made, including patient screening, perioperative rehabilitation, allograft preservation and transportation, enhancement of nerve regeneration, understanding of cortical plasticity, and immunomodulatory strategies. Ethical and psychosocial issues remain at the forefront when evaluating potential pediatric VCA recipients. For ethically and rigorously screened pediatric patients with debilitating upper extremity absence, VCA is a compelling option to restore form and function and has a promising future.

Limitations and limits and of vascularized composite allotransplantations: can we reach the holy grail?

In recent times, vascularized composite allotransplantation (VCA) have been gaining more attention and applications. Currently, VCA are at the highest level of the reconstruction pyramid, and thus the effects expected after them are intended to outweigh what the 'classical' reconstructive surgery can offer us, including even the most advanced microsurgical techniques. Over 40 patients have received a partial or full-face transplant. Others have received penis, uterus, larynx, abdominal wall, and lower extremity transplants. Each type of VCA has its own problems and limitations. However, resolving the limits defined by immunosuppression and improved donor selection would revolutionize all of them. Defining the limits and limitations of given procedures will not only allow for better preparation of transplant teams but will also help in determining the direction of future research.

Current and future regulatory and financial challenges in vascularized composite allotransplantation.

To discuss current and future regulatory and financial issues affecting the field of vascularized composite allotransplantation (VCA). Vascularized composite allografts are regulated by the US Department of Health and Human Services Organ Procurement and Transplantation Network Final Rule (42 CFR part 121) in the United States and Directive 2010/53/EU of the European Parliament and the Council of 7 July 2010 in the European Union (EU). However, in the United States and most of the EU, VCA is not yet paid for by insurance or third-party payers and many centers depend upon grant funding, philanthropic gifts, and/or supplemental hospital/institutional funding strategies to pay for the transplants and postoperative care. In the absence of randomized clinical trial data, which is infeasible for studying VCA outcomes, consensus data sets are needed to document these procedures' value proposition and have them accepted as part of the standard of care. Procedure and immunosuppression protocol variability applied to a small patient cohort necessitates collaborative efforts by field experts to devise creative approaches, such as determining return-on-investment for anatomical subunits, to better understand these transplants' value and impact on patient quality-of-life.

The past the present and the future of face transplantation

Face transplantation represents vascularized composite allotransplantation (VCA) organ and became one of the most rewarding reconstructive options for severely disfigured patients. This review summarizes the past, current and future challenges of face transplantation, based on our experience and literature reports. In 2005, first partial face transplantation was reported by French team. In 2008, we have performed the US first near-total face transplantation. Currently, more than 40 face transplant cases were reported worldwide. Based on the outcomes of our three patients and the literature reports, face transplantation improved aesthetics, function and the quality of life of face transplant patients. However, there are still many challenges encountered including the side effects of immunosuppressive protocols, the psychological and social problems as well as the financial challenges which need to be address in the near future to maintain face transplantation in the armamentarium of reconstructive surgery. Currently, feasibility of face transplantation was confirmed; however, the life-long immunosuppressive protocols bearing serious side effects are still required to prevent face rejection. Thus, for the future of face and other VCA, novel approaches of cell-based therapies or engineered scaffolds should be developed to make face transplantation safer.