# Vascularised Composite Allotransplantation: Emerging Applications in Reconstructive Surgery and Solid Organ Transplantation

## TL;DR

Vascularised composite allotransplantation is a growing field in reconstructive and transplant surgery, offering new solutions for complex tissue and organ replacement.

## Contribution

This review highlights the expanding clinical applications and emerging innovations in vascularised composite allotransplantation.

## Key findings

- Abdominal wall transplantation has introduced the sentinel skin flap concept for monitoring organ rejection.
- Acute rejection affects up to 89% of VCA recipients, with significant complications from immunosuppression.
- Machine perfusion and immunomodulation strategies show promise in improving graft outcomes and reducing immunosuppression burden.

## Abstract

Vascularised composite allotransplantation (VCA) has an evolving role in the reconstruction of complex functional and aesthetic deficits non-amenable to autologous or implant-based reconstructive modalities. International applications of VCA span upper extremity, face, abdominal wall, uterus, and penile transplantation, with more than 300 procedures performed worldwide. Among these, abdominal wall transplantation has uniquely contributed to the development of the sentinel skin flap (SSF) concept, in which solid organ transplant patients undergo simultaneous transplantation of a solid organ and a donor-derived vascularised skin flap, with the skin component of the SSF being trialled internationally as a means of monitoring for rejection within the solid organ allograft. Despite growing clinical success, VCA continues to face substantial barriers to wider adoption. Acute rejection remains highly prevalent, affecting up to 89% of recipients, with significant morbidity linked to intensive systemic immunosuppression. Challenges are further amplified by the unique immunological heterogeneity of composite grafts, ethical concerns surrounding identity-linked tissues, and the lack of standardised outcomes reporting across VCA subtypes. Advances in machine perfusion technologies and emerging cellular and biomaterial-based immunomodulation strategies show promise in reducing immunosuppression burden and improving graft longevity. This review outlines the current state of VCA, including clinical applications, outcomes, and mechanistic insights from pre-clinical studies, while highlighting key ethical considerations and evolving regulatory frameworks. Future progress will depend on standardised reporting systems, improved donor–recipient matching, better understanding of ischemia–reperfusion injury, and the development of next-generation immunosuppressive/immuno-modulatory therapies. Collectively, these innovations position VCA as a rapidly advancing field with significant potential to redefine reconstructive and transplant surgery.