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Topic: Peripheral Nerve Repair and Regeneration

Nerve regeneration in vascularized

composite allotransplantation: current

strategies and future directions

Anirudh Arun, Nicholas B. Abt, Sami Tuffaha, Gerald Brandacher, Angelo A. Leto Barone
Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Address for correspondence: Dr. Angelo A. Leto Barone, Department of Plastic and Reconstructive Surgery, Johns Hopkins University School
of Medicine, Baltimore, MD 21287, USA. E-mail: aletobarone@jhmi.edu

ABSTRACT
Vascularized composite allotransplantation (VCA) has emerged as a viable treatment option for limb
and face reconstruction of severe tissue defects. Functional recovery after VCA requires not only
effective immunosuppression, but also consideration of peripheral nerve regeneration to facilitate
motor and sensory reinnervation of donor tissue. At the time of transplantation, the donor and
recipient nerves are typically coapted in an end-to-end fashion. Following transplantation, there are
no therapies available to enhance nerve regeneration and graft reinnervation, and functional outcomes
are dependent on the recipients’ innate regenerative capacities. Functional outcomes to date have been
promising, but there is still much room for improvement, studies have demonstrated reliable return of
protective sensation (pain, thermal, gross tactile), while discriminative sensation and motor function
show more inconsistent results. In order to maximize the benefit afforded to the by VCA, we must
develop consistent and reliable procedures and therapies to ensure effective nerve regeneration and
functional outcomes. New technologies, such as nerve guidance conduits and fibrin glues, and the use
of stem cells to facilitate nerve regeneration remain untested in VCA but are proving worthwhile in
the context of peripheral nerve repair. VCA presents a unique set of challenges with regards to surgical
techniques, postoperative regimen, and health of donor tissue. In this review, we discuss current
challenges underlying achievement of nerve regeneration in VCA and discuss novel technologies and
approaches to translate nerve regeneration into functional restoration.

Key words:
Adipose-derived stem cells, allograft, fibrin glue, nerve regeneration, tacrolimus, vascularized
composite allotransplantation

INTRODUCTION the transplanted tissue, whereas SOT generally involves
one or a few organs and associated cell types, VCA
The field of vascularized composite allotransplantation (VCA) tissues are composed of skin, vascular structures, nerves,
has rapidly developed over the past few decades, propelled muscles, bone, and connective tissue. The enhanced
[1]
by major advancements in surgical technique and immunogenicity of such composite tissues proved to be
posttransplant immunosuppression. VCA differs from a major roadblock in the success of these transplants in
solid organ transplantation (SOT) in the composition of the long‑term, but the development and use of multiple
immunosuppressive drugs, such as tacrolimus (FK506),
Access this article online have significantly reduced incidence of rejection. VCA can
[2]
Quick Response Code: currently be performed in various body regions, including,
Website:
www.parjournal.net but not limited to, the hand, the proximal upper extremity,
and the face. [1]

DOI: A major challenge of VCA over SOT is that reperfusion
10.4103/2347-9264.158853 of tissues is not sufficient to restore function, instead,
functional recovery in VCA is dependent on the recipient’s

226 Plast Aesthet Res || Vol 2 || Issue 4 || Jul 15, 2015