Vascularized composite allotransplantation in children: what we can learn from solid organ transplantation

Facial Transplantation

Facial transplantation represents a unique surgical solution for challenging facial injury patterns in which conservative reconstructive techniques fail to provide a satisfactory functional and aesthetic result. With advances in the field of vascularized composite allotransplantation over the past 15 years, more than 40 of these procedures have been performed worldwide with two recent reports of facial re-transplantation. In this article we discuss the multidisciplinary approach that is required for successful transplantation as well as the surgical techniques used and postoperative management. With ongoing research, recent technological innovation, and increased efforts to promote greater generalizability and transparency in this field, patients with these complex injuries will continue to see improvements in their treatment options, and thus quality of life.

The current outcomes and future challenges in pediatric vascularized composite allotransplantation

PURPOSE OF REVIEW

We review the outcomes and future challenges associated with pediatric vascularized composite allotransplantation, including follow-up data from our bilateral pediatric hand-forearm transplantation.

RECENT FINDINGS

In 2015, the first heterologous pediatric upper extremity hand-forearm transplant was performed at the Children's Hospital of Philadelphia, and in 2019, the first pediatric neck reconstructive transplantation was performed in Poland. The 5-year follow-up of the pediatric upper extremity recipient demonstrates similar growth rates bilaterally, an increase in bone age parallel to chronologic age, and perhaps similar overall growth to nontransplant norms. The pediatric upper extremity recipient continues to make gains in functional independence. He excels academically and participates in various extracurricular activities. Future challenges unique to the pediatric population include ethical issues of informed consent, psychosocial implications, limited donor pool, posttransplant compliance issues, and greater life expectancy and therefore time to inherit the many complications of immunosuppression.

SUMMARY

Currently, we recommend pediatric vascularized composite allotransplantation (VCA) for bilateral upper extremity amputees, preferably on immunosuppression already, and those patients who would have the most potential gain not available through standard reconstructive techniques while being able to comply with postoperative immunosuppression protocols, surveillance, rehabilitation, and follow-up.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The landscape of vascularized composite allograft donation in the United States

PURPOSE OF REVIEW

Vascularized composite allograft (VCA) donation and transplantation has now demonstrated feasibility and impact to the lives of patients suffering from devastating and traumatic injury. This review summarizes the current landscape of VCA donation in the United States.

RECENT FINDINGS

VCA donations are nonlife-saving allografts, for nonlife-saving transplants - and therefore, conservative donor selection focused on the optimization of donors for the lowest risk to transplant recipients is paramount. VCA donors in the United States are a demographically and clinically diverse group that largely reflects the characteristics of the VCA candidates waiting for transplants. Public opinion about VCA donation is generally supportive, but has lower support for VCA transplants than for solid organ transplants.

SUMMARY

As an emerging area of transplantation, VCA donation is evolving in the United States with growing interest by the public, and those suffering from catastrophic injury for which reconstructive transplantation may offer excellent outcomes and a high quality of life.