Exploring the neuroregenerative potential of tacrolimus

Introduction: The clinical use of tacrolimus is characterized by many side effects which include neurotoxicity. In contrast, tacrolimus has also shown to have neuroregenerative properties. On a molecular level, the mechanisms of action could provide us more insight into understanding the neurobiological effects. The aim of this article is to review current evidence regarding the use of tacrolimus in peripheral nerve injuries. Areas covered: Available data on tacrolimus’ indications were summarized and molecular mechanisms were elucidated to possibly understand the conflicting neurotoxic and neuroregenerative effects. The potential clinical applications of tacrolimus, as immunosuppressant and enhancer of nerve regeneration in peripheral nerve injuries, are discussed. Finally, concepts of delivery are explored. Expert opinion: It is unclear what the exact neurobiological effects of tacrolimus are. Besides its known calcineurin inhibiting properties, the mechanism of action of tacrolimus is mediated by its binding to FK506-binding protein-52, resulting in a bimodal dose response. Experimental models found that tacrolimus administration is preferred up to three days prior to or within 10 days post-nerve reconstruction. Moreover, the indication for the use of tacrolimus has been expanding to fields of dermatology, ophthalmology, orthopedic surgery and rheumatology to improve outcomes after various indications.