Immunology of vascularized composite allotransplantation: a primer for hand surgeons

From replantation to transplantation: The evolution of orthoplastic extremity reconstruction

For more than six decades, the use of the operating microscope for extremity surgery has led to remarkable advances in the management of orthopedic trauma, tumors, infections, and congenital differences. The microsurgical reconstructive ladder ascends from basic microsurgical procedures such as a digital artery or nerve repair to more complex procedures such as autologous tissue transplantation. Functional muscle transfers, toe-to-hand transfers, and recently vascularized composite allotransplantation are the highest rungs on this ladder that help restore extremity function. The development of the orthoplastic approach over the last three decades simultaneously integrates the principles and practices of both orthopedic surgery and plastic surgery for optimal care and salvage of extremities. Clinical, anatomic, and basic science research in reconstructive microsurgery has resulted in significant improvements in extremity salvage, reconstruction, and restoration.

Hand allotransplantation: operating room set-up and team coordination

Vascularized composite allotransplantion requires careful planning and precise execution. The Director of the Hand Transplant Program must coordinate many personnel including nurses, anesthesiologists, transplant coordinators, surgeons, support staff, and hospital administrators. The operation is performed only after surgical rehearsal has reinforced the specialized role of each of these team members and the workflow of equipment and personnel has been optimized.

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.

Hand disease in scleroderma: a clinical correlate for chronic hand transplant rejection

Abstract

Chronic rejection remains a potential long-term consequence of hand composite tissue allotransplantation (CTA). Scleroderma has already been proposed as a model for chronic facial allograft rejection based on potential parallels of observed progression of disease and pathophysiology course. This study proposes a similar model for how chronic rejection may manifest itself in the context of hand CTA through the functional and psychological assessment of patients with scleroderma, should it occur.

Methods

100 consecutive patients with a clinical diagnosis of scleroderma were recruited into the study. Subjective assessment of static hand disfigurement was carried out through the use of standardised digital photographs. Hand function was assessed through the measurement of active range of motion (AROM) and using the activities of daily living (ADL) and Disabilities of the Arm, Shoulder & Hand (DASH) questionnaire. Psychological and quality of life evaluation comprised the Hospital Anxiety Depression Scale (HADS) and the SF36 health survey.

Results

Examination of standardised digital photographs of subjects revealed a variety of hand changes characteristic of scleroderma, ranging from mild to moderate through to severe. Objective assessment of hand disfigurement did not correlate with duration of disease, nor psychological distress. However, individuals with worsening disfigurement demonstrated poorer AROM. Longitudinally no deterioration in terms of function was seen over time in terms of the DASH and ADL results. Nevertheless deterioration of function did have a significant impact on quality of life. Overall HADS showed 22% of individuals as suffering from clinical levels of anxiety and 10% from clinical depression.

Conclusion

Chronic rejection has not yet occurred in any of the hand transplants performed to date. Scleroderma results in a spectrum of chronic functional and psychological disability that provides a model for the potential outcome of chronic hand allograft rejection. Findings from this study provide insight into the impact of this progressive disease for patients and contribute to the information and consent process for patients considering hand composite tissue transplantation.

Mesenchymal stem cells as immunomodulators in a vascularized composite allotransplantation

Vascularized composite allotransplantations (VCAs) are not routinely performed for tissue reconstruction because of the potentially harmful adverse effects associated with lifelong administration of immunosuppressive agents. Researchers have been eagerly seeking alternative methods that circumvent the long-term use of immunosuppressants. Mesenchymal stem cells (MSCs) show promise as an immunomodulatory therapeutic agent and are currently being tested in preclinical and clinical settings as therapies for autoimmune disorders or transplant rejection. The mechanisms by which MSCs modulate the immune response are still under thorough investigation, but these most likely involve expression of local factors influencing T-cell regulation, modulation of cytokine expression (e.g., IL-10, TGF-β, TNF-α, INF-γ, etc.), and interactions with dendritic or antigen presenting cells. In this paper, we summarize the current understanding of immunomodulation achieved by MSC therapies and introduce a possible outline for future clinical applications in VCA.