The Effect of Autologous Fat Graft with Different Surgical Repair Methods on Nerve Regeneration in a Rat Sciatic Nerve Defect Model:

Electrospun PCL Nerve Wrap Coated with Graphene Oxide Supports Axonal Growth in a Rat Sciatic Nerve Injury Model

Background/Objectives: Peripheral nerve injuries (PNIs) are a debilitating problem, resulting in diminished quality of life due to the continued presence of both chronic and acute pain. The current standard of practice for the repair of PNIs larger than 10 mm is the use of autologous nerve grafts. Autologous nerve grafts have limitations that often result in outcomes that are not sufficient to remove motor and sensory impairments. Bio-mimetic nanocomposite scaffolds combined with mesenchymal stem cells (MSCs) represent a promising approach for PNIs. In this study, we investigated the potential of an electrospun wrap of polycaprolactone (PCL) + graphene oxide (GO), with and without xenogeneic human adipose tissue-derived MSCs (hADMSCs) to use as a platform for neural tissue engineering. Methods: We evaluated, in vitro and in vivo, the potential of the nerve wrap in providing support for axonal growth. To establish the rat sciatic nerve defect model, a 10 mm long limiting defect was created in the rat sciatic nerve of 18 Lewis rats. Rats treated with the nanocomposites were compared with autograft-treated defects. Gait, histological, and muscle analyses were performed after sacrifice at 12 weeks post-surgery. Results: Our findings demonstrate that hADMSCs had the potential to transdifferentiate into neural lineage and that the nanocomposite successfully delivered hADMSCs to the injury site. Histologically, we show that the PCL + GO nanocomposite with hADMSCs is comparable to the autologous nerve graft, to support and guide axonal growth. Conclusions: The novel PCL + GO nerve wrap and hADMSCs used in this study provide a foundation on which to build upon and generate future strategies for PNI repair.

Biohacking Nerve Repair: Novel Biomaterials, Local Drug Delivery, Electrical Stimulation, and Allografts to Aid Surgical Repair

The regenerative capacity of the peripheral nervous system is limited, and peripheral nerve injuries often result in incomplete healing and poor outcomes even after repair. Transection injuries that induce a nerve gap necessitate microsurgical intervention; however, even the current gold standard of repair, autologous nerve graft, frequently results in poor functional recovery. Several interventions have been developed to augment the surgical repair of peripheral nerves, and the application of functional biomaterials, local delivery of bioactive substances, electrical stimulation, and allografts are among the most promising approaches to enhance innate healing across a nerve gap. Biocompatible polymers with optimized degradation rates, topographic features, and other functions provided by their composition have been incorporated into novel nerve conduits (NCs). Many of these allow for the delivery of drugs, neurotrophic factors, and whole cells locally to nerve repair sites, mitigating adverse effects that limit their systemic use. The electrical stimulation of repaired nerves in the perioperative period has shown benefits to healing and recovery in human trials, and novel biomaterials to enhance these effects show promise in preclinical models. The use of acellular nerve allografts (ANAs) circumvents the morbidity of donor nerve harvest necessitated by the use of autografts, and improvements in tissue-processing techniques may allow for more readily available and cost-effective options. Each of these interventions aid in neural regeneration after repair when applied independently, and their differing forms, benefits, and methods of application present ample opportunity for synergistic effects when applied in combination.

The Effects of Adipose-Derived Mesenchymal Stem Cells and Adipose-Derived Mesenchymal Stem Cell-Originating Exosomes on Nerve Allograft Regeneration: An Experimental Study in Rats

INTRODUCTION

Nerve regeneration has been the subject of many studies because of its complex mechanism and functional outcome. Mesenchymal stem cells and exosomes are promising factors in regeneration in many areas. Reconstruction of nerve defects is a controversial issue, and nerve allografts are promising alternatives with many advantages. In this study, it is aimed to evaluate the nerve regeneration in cellularized and decellularized nerve allografts and whether it is possible to accelerate this process with adipose-derived mesenchymal stem cells (ad MSC) or ad MSC-originating exosomes.

METHOD

This study was performed with 36 Lewis and 18 Brown Norway isogenic male rats aged 10 to 12 weeks and weighing 300 to 350 g. The Lewis rats were divided into 6 groups. Nerve allografts at a length of 12 mm that were obtained from the Brown Norway rats' proximal portion of both sciatic nerve branching points were coapted as cellularized in group A and decellularized in group B to the sciatic nerve defects of the Lewis rats. Group A received oral tacrolimus (0.2 mg/kg) for 30 days. Perineural saline (A1-B1), ad MSC (A2-B2), or ad MSC-originating exosomes (A3-B3) were applied to these groups. Walking track analysis, pinch-prick test and electromyelography were applied at the 8th and 16th weeks following surgery. Nerves were examined histopathologically at the 16th week.

RESULTS

Between cellularized groups, better results were shown in A3 about axon-myelin regeneration/organization (P = 0.001), endoneural connective tissue (P = 0.005), and inflammation (P = 0.004). Better results were shown in the B2 and B3 groups electromyelographicaly about latency period (P = 0.033) and action potential (P = 0.008) at late period, and histomorphologicaly at vascularization (P = 0.012).

DISCUSSION

It is argued that regeneration is accelerated with decellularization of nerve allografts by removing the chondroidin sulfate proteoglycans. The positive effects of stem cells are derived by exosomes without the cell-related disadvantages. In this study, better results were obtained by decellularization and perineural application of ad MSC and/or ad MSC exosome.

The Combined Use of Curcumin and Platelet-Rich Plasma Enhances Axonal Regeneration in Acute Nerve Injuries: An Experimental Study in a Rat Model

Introduction  The aim of this study was to determine if the combined use of curcumin and platelet-rich plasma (PRP) improves the axonal regeneration process in acutely repaired nerve injuries. Materials and Methods  The right sciatic nerves of 32 Holtzman albino rats were transected and immediately repaired. Four treatments were randomly allocated: (1) nerve repair only; (2) nerve repair + local PRP; (3) nerve repair + intraperitoneal curcumin; and (4) nerve repair + local PRP + intraperitoneal curcumin. Clinical (estimation of sciatic functional index) and electrophysiological outcomes were assessed 4 and 12 weeks after surgery, and histologic evaluations performed 12 weeks after surgery. Results  Group IV (PRP + curcumin) resulted in significantly better outcomes across all the evaluation parameters, compared with the other three groups ( p  < 0.05). Additionally, when used as single adjuvants, both the curcumin (group III) and PRP (group II) groups showed significant improvement over the control group ( p  < 0.05). No significant differences were found between PRP and curcumin when used as sole adjuvants. Conclusion  The combined administration of curcumin + PRP as adjuvants to nerve repair could enhance axonal regeneration in terms of clinical, electrophysiological, and histological parameters in a rat model of acute sciatic nerve injury.

Autologous Fat Grafting in the Upper Extremity: Defining New Indications

Autologous fat grafting is a commonly used technique in plastic surgery that can also be applied broadly in hand surgery. We present a case series to demonstrate the diverse indications for fat grafting in hand surgery.

Methods

We retrospectively reviewed cases of fat grafting in the upper extremity in 2020. Cases representing a unique application of fat grafting were identified. Patient data, including demographics, diagnoses, preoperative and postoperative assessments, complications, patient satisfaction, and surgical operative reports, were recorded.

Results

Five patients representing distinct indications for autologous fat grafting in the upper extremity were identified. Indications included hand rejuvenation (20.0%), burn/scar management (20.0%), tenolysis (20.0%), revision nerve decompression (20.0%), and carpometacarpal joint arthritis (20.0%). Average patient age was 60.4 years (range, 42-71). Average volume of fat injected was 15.2 ml (range, 1-37 ml). No major complications were noted (0.0%). All patients expressed satisfaction with their overall result with good functional outcomes (100%).

Conclusions

Autologous fat grafting can be applied broadly in hand surgery. Indications for fat grafting in hand surgery include hand rejuvenation, burn/scar management, tenolysis, revision nerve decompression, and thumb carpometacarpal arthritis. Hand surgeons can easily incorporate fat grafting into their daily practice. Current literature supports fat grafting as a viable technique in hand surgery with lower-level studies.

Role of stem cells-based in facial nerve reanimation: A meta-analysis of histological and neurophysiological outcomes

BACKGROUND

Treatments involving stem cell (SC) usage represent novel and potentially interesting alternatives in facial nerve reanimation. Current literature includes the use of SC in animal model studies to promote graft survival by enhancing nerve fiber growth, spreading, myelinization, in addition to limiting fibrotic degeneration after surgery. However, the effectiveness of the clinical use of SC in facial nerve reanimation has not been clarified yet.

AIM

To investigate the histological, neurophysiological, and functional outcomes in facial reanimation using SC, compared to autograft.

METHODS

Our study is a systematic review of the literature, consistently conducted according to the preferred reporting items for systematic reviews and meta-analyses statement guidelines. The review question was: In facial nerve reanimation on rats, has the use of stem cells revealed as effective when compared to autograft, in terms of histological, neurophysiological, and functional outcomes? Random-effect meta-analysis was conducted on histological and neurophysiological data from the included comparative studies.

RESULTS

After screening 148 manuscript, five papers were included in our study. 43 subjects were included in the SC group, while 40 in the autograft group. The meta-analysis showed no significative differences between the two groups in terms of myelin thickness [CI: -0.10 (-0.20, 0.00); I² = 29%; P = 0.06], nerve fibers diameter [CI: 0.72 (-0.93, 3.36); I² = 72%; P = 0.6], compound muscle action potential amplitude [CI: 1.59 (0.59, 3.77); I² = 89%; P = 0.15] and latency [CI: 0.66 (-1.01, 2.32); I² = 67%; P = 0.44]. The mean axonal diameter was higher in the autograft group [CI: 0.94 (0.60, 1.27); I² = 0%; P ≤ 0.001].

CONCLUSION

The role of stem cells in facial reanimation is still relatively poorly studied, in animal models, and available results should not discourage their use in future studies on human subjects.

Adipose Tissue Uses in Peripheral Nerve Surgery

Currently, many different techniques exist for the surgical repair of peripheral nerves. The degree of injury dictates the repair and, depending on the defect or injury of the peripheral nerve, plastic surgeons can perform nerve repairs, grafts, and transfers. All the previously listed techniques are routinely performed in human patients, but a novel addition to these peripheral nerve surgeries involves concomitant fat grafting to the repair site at the time of surgery. Fat grafting provides adipose-derived stem cells to the injury site. Though fat grafting is performed as an adjunct to some peripheral nerve surgeries, there is no clear evidence as to which procedures have improved outcomes resultant from concomitant fat grafting. This review explores the evidence presented in various animal studies regarding outcomes of fat grafting at the time of various types of peripheral nerve surgery.

Autologous fat grafting for nerve regeneration and neuropathic pain: current state from bench-to-bedside

Despite recent advances in microsurgical techniques, functional recovery following peripheral nerve injury remains slow and inadequate. Poor peripheral nerve regeneration not only leaves patients with significant impairments, but also commonly leads to the development of debilitating neuropathic pain. Recent research has demonstrated the potential therapeutic benefits of adipose-derived stem cells, to enhance nerve regeneration. However, clinical translation remains limited due to the current regulatory burdens of the US FDA. A reliable and immediately translatable alternative is autologous fat grafting, where native adipose-derived stem cells present in the transferred tissue can potentially act upon regenerating axons. This review presents the scope of adipose tissue-based therapies to enhance outcomes following peripheral nerve injury, specifically focusing on their role in regeneration and ameliorating neuropathic pain.

An update on the management of nerve gaps

No abstract required

Successful Immediate Staged Breast Reconstruction with Intermediary Autologous Lipotransfer in Irradiated Patients

As indications for radiotherapy in mastectomized patients grow, the need for greater reconstructive options is critical. Preliminary research suggests an ameliorating impact of lipotransfer on irradiated patients with expander-to-implant reconstruction. Herein, we present our technique using lipotransfer during the expansion stage to facilitate implant placement.

Neuroregenerative effects of polyethylene glycol and FK-506 in a rat model of sciatic nerve injury

The recently introduced polyethylene glycol (PEG) treatment restores axonal continuity after nerve injury, leading to rapid recovery of nerve function. The impact of PEG therapy on neuroregeneration has not yet been compared with any intervention with an established proneuroregenerative potential. FK-506 is an immunosuppressive agent with documented proneuroregenerative potential in nerve injury models. The aim of this study was to compare the effects of PEG therapy and preinjury FK-506 administration in rats with sciatic nerve transection injury. Four groups of male Sprague Dawley rats (seven per group) underwent sciatic nerve transection with primary repair. Group A received placebo injections, group B placebo injections and PEG treatment, group C FK-506 injections, and group D both FK-506 injections and PEG treatment. Clinical outcomes were assessed by the skin prick test and Sciatic Functional Index (SFI). Regenerated nerves underwent histomorphometric analysis. The histomorphometric analysis demonstrated that compared with the controls, nerve specimens from all treated groups showed signs of enhanced neuroregeneration (higher mean axonal area) (p < 0.001). The histomorphometric parameters for group D (PEG + FK-506), mean axonal area (p < 0.001) and axonal count (p > 0.05), were significantly better than those in the other study groups. The Form factor was closest to its optimal values in group B (p < 0.0001). At the end of the study, mean skin prick test scores in all treated groups were significantly higher than those in controls (p > 0.05). During the first postoperative week, PEG-treated rats (groups B and D) presented with higher values of the SFI than animals from groups A and C, but the difference was not statistically significant. Combined therapy with PEG and FK-506 seems to produce better neuroregeneration outcomes than a simple suture-based repair complemented with either PEG or FK-506 treatment.

State-of-the-Art Techniques in Treating Peripheral Nerve Injury

BACKGROUND

Peripheral nerve injuries remain a major clinical concern, as they often lead to chronic disability and significant health care expenditures. Despite advancements in microsurgical techniques to enhance nerve repair, biological approaches are needed to augment nerve regeneration and improve functional outcomes after injury.

METHODS

Presented herein is a review of the current literature on state-of-the-art techniques to enhance functional recovery for patients with nerve injury. Four categories are considered: (1) electroceuticals, (2) nerve guidance conduits, (3) fat grafting, and (4) optogenetics. Significant study results are highlighted, focusing on histologic and functional outcome measures.

RESULTS

This review documents the current state of the literature. Advancements in neuronal stimulation, tissue engineering, and cell-based therapies demonstrate promise with regard to augmenting nerve regeneration and appropriate rehabilitation.

CONCLUSIONS

The future of treating peripheral nerve injury will include multimodality use of electroconductive conduits, fat grafting, neuronal stimulation, and optogenetics. Further clinical investigation is needed to confirm the efficacy of these technologies on peripheral nerve recovery in humans, and how best to implement this treatment for a diverse population of nerve-injured patients.

Preliminary results with non-centrifuged autologous fat graft and percutaneous aponeurotomy for treating Dupuytren's disease

The aim of this study was to describe our experience with treating Dupuytren's disease using needle aponeurotomy and non-centrifuged autologous fat grafting. The study included 17 patients (18 hands). Patients were treated with needle aponeurotomy and non-centrifuged autologous fat graft under general anesthesia. The fat grafts were injected into the surgical area so as to stay in contact with the operated site. An extension splint was used for 1 week postoperatively and the patients received hand therapy for 3 weeks. Before the treatment, the contracture in the proximal interphalangeal and metacarpophalangeal joints was a mean of 45.06 ± 13.44 degrees and 36.56 ± 13.09 degrees, respectively. It was 1.61 ± 1.65 and -0.56 ± 3.78 degrees at 3 months, respectively. The difference between these measurements was statistically significant. The mean follow-up period was 12 months. The results were satisfactory and no complications were observed during the follow-up period. Based on the results of the study, percutaneous aponeurotomy with non-centrifuged autologous fat grafting was found to have significantly beneficial effects in the treatment of Dupuytren's disease.

Nerve regeneration techniques respecting the special characteristics of the inferior alveolar nerve

PURPOSE

The aim of this study was to examine the in situ regeneration of the inferior alveolar nerve (IAN) in its bony channel, using autologous tissue in combination with a recombinant human nerve growth factor (rhNGF).

MATERIALS AND METHODS

A total of 20 New Zealand rabbits were randomly divided into five groups. Following dissection of the IAN, the animals underwent reconstruction either with muscle tissue (groups 1 and 2) or with fat tissue (groups 3 and 4). In group 5 (control), the dissected nerve was resected and reconstructed by placement of the reversed autologous segment. After 2 and 4 weeks, 1 mL rhNGF was locally injected in groups 1 and 3. Nerve function was monitored by measuring the jaw-opening reflex using electromyography for a period of 24 weeks.

RESULTS

Regeneration of the nerve was achieved in all groups, but preoperative threshold values were not achieved. Comparing the experimental groups to the control, there was a significant difference in favor of the autologous nerve reconstruction. Differences between the experimental groups remained statistically not significant.

CONCLUSION

Regeneration of the IAN with autologous tissue is possible, but without achieving preoperative thresholds. Additional injection of a growth factor seems to improve the speed of regeneration for fat and muscle grafts.