Chan, K. Ming

AbstractBackgroundThe aim of this study was to investigate the combined effect of mesenchymal stem cells (MSC) and local delivery of tacrolimus (FK506) on nerve regeneration when applied to nerve autografts and decellularized allografts.MethodsA three‐dimensional in vitro compartmented cell culture system consisting of a neonatal dorsal root ganglion adjacent to a nerve graft was used to evaluate the regenerating neurites into the peripheral nerve scaffold. Nerve autografts and allografts were treated with (i) undifferentiated MSCs, (ii) FK506 (100 ng/mL) or (iii) both (N = 9/group). After 48 hours, neurite extension was measured to quantify nerve regeneration and stem cell viability was evaluated.ResultsStem cell viability was confirmed in all MSC‐treated grafts. Neurite extension was superior in autografts treated with FK506, and MSCs and FK506 combined (p < 0.001 and p = 0.0001, respectively), and autografts treated with MSCs (p = 0.12) were comparable to untreated autografts. In allografts, FK506 treatment and combined treatment were superior to controls (p < 0.001 and p = 0.0001, respectively), and treatment with MSCs (p = 0.09) was comparable to controls. All autograft groups were superior compared to their respective allograft treatment group (p < 0.05) in neurite extension.ConclusionsAlone, either MSC or FK506 treatment improved neurite outgrowth, and combined they further enhanced neurite extension in both autografts and allografts.

AbstractThe application of scaffold‐based stem cell transplantation to enhance peripheral nerve regeneration has great potential. Recently, the neuroregenerative potential of tacrolimus (a U.S. Food and Drug Administration‐approved immunosuppressant) has been explored. In this study, a fibrin gel‐based drug delivery system for sustained and localized tacrolimus release was combined with rat adipose‐derived mesenchymal stem cells (MSC) to investigate cell viability in vitro. Tacrolimus was encapsulated in poly(lactic‐co‐glycolic) acid (PLGA) microspheres and suspended in fibrin hydrogel, using concentrations of 0.01 and 100 ng/ml. Drug release over time was measured. MSCs were cultured in drug‐released media collected at various days to mimic systemic exposure. MSCs were combined with (i) hydrogel only, (ii) empty PLGA microspheres in the hydrogel, (iii) 0.01, and (iv) 100 ng/ml of tacrolimus PLGA microspheres in the hydrogel. Stem cell presence and viability were evaluated. A sustained release of 100 ng/ml tacrolimus microspheres was observed for up to 35 days. Stem cell presence was confirmed and cell viability was observed up to 7 days, with no significant differences between groups. This study suggests that combined delivery of 100 ng/ml tacrolimus and MSCs in fibrin hydrogel does not result in cytotoxic effects and could be used to enhance peripheral nerve regeneration.

ABSTRACTIntroduction: Numerous methods for motor unit number estimation (MUNE) have been developed. The objective of this article is to summarize and compare the major methods and the available data regarding their reproducibility, validity, application, refinement, and utility.Methods: Using specified search criteria, a systematic review of the literature was performed. Reproducibility, normative data, application to specific diseases and conditions, technical refinements, and practicality were compiled into a comprehensive database and analyzed.Results: The most commonly reported MUNE methods are the incremental, multiple‐point stimulation, spike‐triggered averaging, and statistical methods. All have established normative data sets and high reproducibility. MUNE provides quantitative assessments of motor neuron loss and has been applied successfully to the study of many clinical conditions, including amyotrophic lateral sclerosis and normal aging.Conclusions: MUNE is an important research technique in human subjects, providing important data regarding motor unit populations and motor unit loss over time.Muscle Nerve50: 884–893, 2014