Peripheral nerve regeneration in rats using nerve graft in a vein conduit pre-filled with platelet-rich fibrin (PRF)

Treatment of peripheral nerve injury is not always satisfactory. To improve results, specific adjuvant methods have been used, such as platelet-rich fibrin (PRF) and vein conduits. The goal of this study was to assess whether use of PRF and vein conduits after nerve suture improves nerve regeneration as measured by a functional score and histomorphometry analysis. Ten isogenic spontaneously hypertensive rats were randomly assigned to 4 experimental procedures: 1) Sham group (n = 10); 2) Nerve graft (NG) group (n = 10); 3) Nerve graft covered with a vein conduit (NGVC) (n = 10); and 4) Nerve graft covered with a vein conduit pre-filled with PRF (NGVCP) (n = 10). Nerve repair results were evaluated on: sciatic functional index (SFI) at 0, 30, 60 and 90 days; morphometric and morphologic analysis of the distal nerve; and histological analysis of Fluoro-Gold® stained motor neurons in the anterior horn of the spinal cord. Compared to the Sham control group, the NGVC and NGVCP groups exhibited lower SFI on all measures. The NGVC group showed improvement in SFI at day 90, which was significant compared to the NG group. Fiber and axon diameters were comparable in the NGVC and NGVCP groups, which were both significantly lower than in the Sham and NG groups. Significant improvement was expected with PRF, but in fact the release of factors from this substance was not as effective as hoped.

A novel cell-free intrathecal approach with PRP for the treatment of spinal cord multiple sclerosis in cats

Background

Multiple sclerosis (MS) is a progressive autoimmune demyelinating disease of the central nervous system. To date, there is no effective therapy for it. Our study aimed to determine the potential role of platelet-rich plasma (PRP) in the treatment of MS in cats.

Methods

The current study was conducted on 15 adult Persian cats that were divided into three groups: control negative, control positive (ethidium bromide (EB)-treated group), and PRP co-treated group (EB-treated group intrathecally injected with PRP on day 14 post-spinal cord injury). PRP was obtained by centrifuging blood on anticoagulant citrate dextrose and activating it with red and green laser diodes. The Basso–Beattie–Bresnahan (BBB) scores were used to assess the motor function recovery on days 1, 3, 7, 14, 20, and 28 following 14 days from EB injection. Moreover, magnetic resonance imaging (MRI) analysis, histopathological investigations, transmission electron microscopy (TEM) studies, and immunohistochemical analysis were conducted, and the gene expressions of nerve growth factors (NGFs), brain-derived neurotrophic factors (BDNF), and stromal cell-derived factors (SDF) were evaluated.

Results

Our results indicated that PRP had a significant ameliorative effect on the motor function of the hindlimbs as early as day 20 and so on. MRI revealed that the size and intensity of the lesion were significantly reduced in the PRP co-treated group. The histopathological and TEM investigations demonstrated that the PRP co-treated group had a significant improvement in the structure and organization of the white matter, as well as a high remyelination capacity. Furthermore, a significant increase in myelin basic protein and Olig2 immunoreactivity as well as a reduction in Bax and glial fibrillar acidic protein immune markers was observed. NGFs were found to be upregulated by gene expression.

Conclusion

As a result, we concluded that the intrathecal injection of PRP was an effective, safe, and promising method for the treatment of MS.

The Optimal Timing of Platelet-Rich Plasma (PRP) Injection for Nerve Lesion Recovery: A Preliminary Study

Introduction

Without appropriate treatment, nerve injuries may result in permanent loss of function. Platelet-rich plasma (PRP) injection is found to help in nerve regeneration. PRP is a concentrated platelet derived from autologous blood with the potential to release various growth factors (GF) to promote nerve regeneration. This study aims to know the best time for PRP injection to promote nerve regeneration.

Methods

This is an experimental in vivo research using male New Zealand white rabbits in the randomized control group posttest only design. Samples were divided into 5 groups (1 control group and 4 treatment groups). The control group without PRP injection and treated groups injected immediately after nerve injury, 3 days, 7 days, and 14 days afterward. Nerve regeneration was evaluated by the histology specimen sacrificed on day 21. Inflammation cells and endoneurium vacuoles were counted as mean percentage of five nerve fragments in each injured nerve sample specimen.

Result

Inflammation cells and vacuole cells increased significantly when PRP was administered 3 days after injury (group 2) (respectively, 14 ± 6.7 and 56.6 ± 11.6) compared to all treatment groups (p < 0.005) (control group, respectively, 6 ± 2.6 and 15.7 ± 9.5). On the other hand, significantly lower endoneurium vacuoles and inflammation cells were found on "the day 14" sample group (respectively, 5 ± 1.3 and 5.2 ± 1.6) compared to all other groups (p < 0.005).

Conclusion

This study found that the best time for injecting PRP for nerve regeneration is 14 days after injury.

Ultrasound-guided platelet-rich plasma injection and multimodality ultrasound examination of peripheral nerve crush injury

Ultrasound-guided platelet-rich plasma (PRP) injection is able to make up for the limitations of applying a single growth factor. The goal of this study was to investigate the effects of serial ultrasound-guided PRP injections of the appropriate concentration on the treatment of sciatic nerve crush injury, and explore the value of multimodality ultrasound techniques in evaluating the prognosis of crushed peripheral nerve. In vitro, optimal concentration of PRP (from 150%, 250%, 450%, and 650%) was screened due for its maximal effect on proliferation and neurotrophic function of Schwann cells (SCs). In vivo, ninety rabbits were equally and randomly divided into normal control, model, PRP-2.5×, PRP-4.5×, and PRP-6.5× groups. The neurological function and electrophysiological recovery evaluation, and the comparison of the multimodality ultrasound evaluation with the histological results of sciatic nerve crush injury were performed to investigate the regenerative effects of PRP at different concentrations on the sciatic nerve crush injury. Our results showed that the PRP with a 4.5-fold concentration of whole blood platelets could significantly stimulate the proliferation and secretion of SCs and nerve repair. The changes in stiffness and blood perfusion were positively correlated with the collagen area percentage and VEGF expression in the injured nerve, respectively. Thus, serial ultrasound-guided PRP injections at an appropriate concentration accelerates the recovery of axonal function. Multimodality ultrasound techniques provide a clinical reference for prognosis by allowing the stiffness and microcirculation perfusion of crush-injured peripheral nerves to be quantitatively evaluated.

Platelet-rich plasma injection versus surgical and medical treatment of mild-moderate carpal tunnel syndrome

Abstract

Carpal tunnel syndrome (CTS) accounts for approximately 90% of peripheral entrapment neuropathy cases. Treatments of CTS as splinting, corticosteroid injection, and surgery are not 100% effective, and alternative treatments are worth exploring. Surgery indicated in patients with persistent numbness, pain, and motor dysfunction. Empirical evidence indicates that many patients with CTS respond to anti-inflammatory medications. Recently, major attention has been drawn to platelet-rich plasma (PRP) for its possible effects on axon regeneration and neurological recovery.

Objectives

To evaluate the therapeutic efficacy of single ultrasound guided PRP injection of CTS versus surgical procedures and medical treatment in patients with mild-moderate CTS regarding pain relief and function improvement.

Methods

Thirty patients were injected in the carpal tunnel with single ultrasound-guided PRP (1–2 ml) injections; 30 patients went to surgical procedure, and 30 patients received conventional medical treatment and hand support. They were followed by using VAS (visual analogue scale), Boston questionnaire for CTS, and nerve conduction study for clinical improvement.

Results

Both groups of patients who had received PRP injection and who underwent to surgery showed improvements in their scores of evaluation parameters at 6 months post intervention, while the third group that received medical treatment shows insignificant improvement at 6 months post treatment.

Conclusion

PRP can be considered as a safe, less invasive, and long-lasting alternative to surgery and effective with one shot session compared to medical treatment in management of mild-moderate CTS.

Trial registration

Clinical trial.govID: NCT04235426.

Unique protocol ID:1472.

Verification date: January 2020.

Efficacy of platelet-rich plasma injection in mild and moderate carpal tunnel syndrome: randomized control study

Background

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy. Typical symptoms and signs include numbness, tingling, pain, or burning sensation in the digits supplied by the median nerve and/or nocturnal paresthesia. Treatments of CTS range from conservative measures to surgical decompression of the median nerve.

Results

The PRP group showed a statistically significant reduction in the visual analog scale, Boston Carpal Tunnel Syndrome Questionnaire, for the severity and the functional capacity scores, and cross-sectional area of the median nerve compared to those of control group 3 months post-treatment (p < 0.05).

Conclusions

Platelet-rich plasma injection in CTS relieves pain and symptom severity and improves functional status but not significantly improve the electrophysiological parameters.

Platelet-rich Plasma and Mesenchymal Stem Cells Local Infiltration Promote Functional Recovery and Histological Repair of Experimentally Transected Sciatic Nerves in Rats

Introduction

Platelet-rich plasma (PRP) products and mesenchymal stem cells (MSCs) seem to have a significant potential as neurogenic therapeutic modulator systems. This study aimed to investigate such biological blood derivatives that could enhance nerve regeneration when applied locally in the primary repair of peripheral nerve transection of an experimental rat model.

Methods

A total of 42 two-month-old male Wistar rats were divided into three “treatment” groups (control, PRP, and MSCs). All the subjects were operated under anesthesia, and the surgical site was infiltrated with either normal saline, PRP derived from the animal’s peripheral blood, or MSCs derived from the animal’s femoral bone marrow. All three groups were also sub-divided into two sub-groups based on the post-operative administration of Non-steroidal anti-inflammatory drugs (NSAIDs) or not in order to evaluate the effect of NSAIDs on the final outcome. Three months post-surgery, electromyography evaluation of both hind limbs (right operated and left non-operated) was performed. The animals were euthanized, and nerve repair specimens were prepared for histology.

Results

PRP group had a significant effect (p<0.05) on the sciatic nerve repair when compared with the control group, whereas the MSC group had a positive effect but was not statistically significant (p=0.2). The number of counted neural axons at the area distal to the nerve repair site were significantly repetitive (p<0.05) in both the PRP and MSC groups when compared with the control group.

Conclusions

Both PRP and MSCs appear to play an essential role in the enhancement of nerve repair in terms of functionality and histology. MSCs group demonstrated a positive effect, whereas the PRP group showed statistically significant better results.

Can platelet-rich fibrin accelerate neurosensory recovery following sagittal split osteotomy? A double-blind, split-mouth, randomized clinical trial

Neurosensory disturbance (NSD) is common following sagittal split osteotomy (SSO) surgery. The aim of this study was to evaluate the effect of platelet-rich fibrin (PRF) on neurosensory recovery following SSO. This double-blind, split-mouth, randomized clinical trial was performed on patients undergoing bilateral SSO. PRF was applied to one side (selected using computer randomization) after the osteotomy and before fixation. The other side served as the control. The two-point discrimination test and a brush directional stroke test were used to assess NSD at 6 and 12 months postoperative. Self-reported paresthesia was documented using a 10-point visual analogue scale (VAS). Twenty-one patients were included in the study. The results of the two-point discrimination test and the number of subjects who reported a true direction in the brush directional stroke test differed significantly between the treatment and control sides (P=0.001). The recovery of NSD (self-reported paresthesia) was better on the treatment side than on the control side (P=0.001). PRF may enhance the recovery of paresthesia following SSO.

Platelet-rich plasma injections for carpal tunnel syndrome: a systematic and comprehensive review

A series of clinical trials focused on the use of ultrasound-guided platelet-rich plasma (PRP) infusions for the treatment of patients with carpal tunnel syndrome (CTS) were published over the last few years. However, the role of PRP for CTS remains unclear. We performed a systematic review according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Two reviewers independently conducted the search using multiple databases: MEDLINE/PubMed, SCOPUS, Cochrane Database, and Web of Science. These databases were searched using terms "platelet" AND "rich" AND "plasma" AND "carpal" AND "tunnel". To maximize the search, backward chaining of references from retrieved papers was also undertaken. From the initial 19 studies, only five met our eligibility criteria. These articles included one randomized controlled double-blind study, one randomized controlled single-blind study, one randomized controlled non-blind study, one case-control study, and one case report. The vast majority of the included studies supported that PRP infusion improved the clinical condition of the patients and that PRP infusion was beneficial for patients with mild-to-moderate CTS. Therefore, PRP seems to be an interesting alternative for the treatment of mild-to-moderate CTS which, still, has not been thoroughly investigated. However, despite the promising results of the present studies, PRP has to be further tested before we reach to a definite conclusion regarding its therapeutic value.

Platelet rich plasma: Effective treatment for repairing of spinal cord injury in rat

Objective

The aim of the present study was to evaluate the effect of PRP on the repair of spinal cord injury in rat model.

Material and methods

Rats were randomly divided into three groups with six rats in each group. Then, spinal cord injury was performed under general anesthesia using “weight dropping” method. Control group included rats receiving normal saline, group two received PRP 1 week after injury; group three received PRP 24 h after injury. The motor function was assessed weekly using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Anterograde tracing was performed for evaluation of axon regeneration.

Result

Motor recovery was significantly better in the rats treated with PRP 24 h after injury than the control group. In the rats treated with PRP 1 week after injury and rats treated with PRP 24 h after injury, the average numbers of BDA-labeled axons were statistically different from the control group.

Conclusion

Our experimental study demonstrated positive effects of platelet rich plasma on nerve regeneration after spinal cord injury.

Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal mechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma (PRP) therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field. Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and (pre-)clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of injured peripheral nerves around dental implants is discussed.

Six-month efficacy of platelet-rich plasma for carpal tunnel syndrome: A prospective randomized, single-blind controlled trial

Recently, a few small reports with short follow-up period have shown clinical benefits of platelet-rich plasma (PRP) for peripheral neuropathy including one pilot study and one small, non-randomized trial in patients with carpal tunnel syndrome (CTS). Therefore, we conducted a randomized, single-blind, controlled trial to assess the 6-month effect of PRP in patients with CTS. Sixty patients with unilateral mild-to-moderate CTS were randomized into two groups of 30, namely the PRP and control groups. In the PRP group, patients were injected with one dose of 3 mL of PRP using ultrasound guidance and the control group received a night splint through the study period. The primary outcome measure was the visual analog scale (VAS) and secondary outcome measures included the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) score, the cross-sectional area (CSA) of the median nerve (MN), electrophysiological findings of the MN, and finger pinch strength. The evaluation was performed before treatment and at 1, 3, and 6 months post-injection. The PRP group exhibited a significant reduction in the VAS score, BCTQ score, and CSA of MN compared to the those of control group 6 months post-treatment (p < 0.05). Our study demonstrates that PRP is a safe modality that effectively relieves pain and improves disability in the patients with CTS.

Epineurial Window Is More Efficient in Attracting Axons than Simple Coaptation in a Sutureless (Cyanoacrylate-Bound) Model of End-to-Side Nerve Repair in the Rat Upper Limb: Functional and Morphometric Evidences and Review of the Literature

End-to-side nerve coaptation brings regenerating axons from the donor to the recipient nerve. Several techniques have been used to perform coaptation: microsurgical sutures with and without opening a window into the epi(peri)neurial connective tissue; among these, window techniques have been proven more effective in inducing axonal regeneration. The authors developed a sutureless model of end-to-side coaptation in the rat upper limb. In 19 adult Wistar rats, the median and the ulnar nerves of the left arm were approached from the axillary region, the median nerve transected and the proximal stump sutured to the pectoral muscle to prevent regeneration. Animals were then randomly divided in two experimental groups (7 animals each, 5 animals acting as control): Group 1: the distal stump of the transected median nerve was fixed to the ulnar nerve by applying cyanoacrylate solution; Group 2: a small epineurial window was opened into the epineurium of the ulnar nerve, caring to avoid damage to the nerve fibres; the distal stump of the transected median nerve was then fixed to the ulnar nerve by applying cyanoacrylate solution. The grasping test for functional evaluation was repeated every 10-11 weeks starting from week-15, up to the sacrifice (week 36). At week 36, the animals were sacrificed and the regenerated nerves harvested and processed for morphological investigations (high-resolution light microscopy as well as stereological and morphometrical analysis). This study shows that a) cyanoacrylate in end-to-side coaptation produces scarless axon regeneration without toxic effects; b) axonal regeneration and myelination occur even without opening an epineurial window, but c) the window is related to a larger number of regenerating fibres, especially myelinated and mature, and better functional outcomes.

Is Platelet-Rich Plasma a Future Therapy in Pain Management?

Platelet-rich plasma (PRP) has the potential to regenerate tissues and decrease pain through the effects of bioactive molecules and growth factors present in alpha granules. Several PRP preparation systems are available with varying end products, doses of growth factors, and bioactive molecules. This article presents the biology of PRP, the preparation of PRP, and the effects PRP-related growth factors have on tissue healing and repair. Based on available evidence-based literature, the success of PRP therapy depends on the method of preparation and composition of PRP, the patient's medical condition, anatomic location of the injection, and the type of tissue injected.

Platelet-Rich Plasma Promotes Axon Regeneration, Wound Healing, and Pain Reduction: Fact or Fiction

Platelet-rich plasma (PRP) has been tested in vitro, in animal models, and clinically for its efficacy in enhancing the rate of wound healing, reducing pain associated with injuries, and promoting axon regeneration. Although extensive data indicate that PRP-released factors induce these effects, the claims are often weakened because many studies were not rigorous or controlled, the data were limited, and other studies yielded contrary results. Critical to assessing whether PRP is effective are the large number of variables in these studies, including the method of PRP preparation, which influences the composition of PRP; type of application; type of wounds; target tissues; and diverse animal models and clinical studies. All these variables raise the question of whether one can anticipate consistent influences and raise the possibility that most of the results are correct under the circumstances where PRP was tested. This review examines evidence on the potential influences of PRP and whether PRP-released factors could induce the reported influences and concludes that the preponderance of evidence suggests that PRP has the capacity to induce all the claimed influences, although this position cannot be definitively argued. Well-defined and rigorously controlled studies of the potential influences of PRP are required in which PRP is isolated and applied using consistent techniques, protocols, and models. Finally, it is concluded that, because of the purported benefits of PRP administration and the lack of adverse events, further animal and clinical studies should be performed to explore the potential influences of PRP.

Platelet-rich plasma guided injections: clinical application in peripheral neuropathies

Platelet-rich plasma (PRP) is defined as an autologous concentrated preparation of platelets and their associated growth factors in a small volume of plasma. The presence of these growth factors has stimulated the scientific community to search about possible benefits of the use of PRP in tissue regeneration. Provided that previously in vitro and animal research demonstrated that PRP could probably play an important role in the treatment of neural tissue disorders, we aimed to review the current literature, regarding the clinical studies that have been conducted to confirm this hypothesis. More specifically, we have reviewed the literature concerning the clinical application of PRP in peripheral neuropathies and investigated if there is strong evidence to establish the use of PRP in clinical practice as a therapeutic option. In contrast with animal studies, we have been able to identify only few clinical data concerning the use of PRP in peripheral neuropathies. We found five trials matched to our research that yields positive and promising results for the future for the application of PRP for the therapy of disorders of the peripheral nervous system. It is obvious that this interesting field of research gives to the scientists the ability to expand it extensively, in terms of both quality and quantity.

An inside-out vein graft filled with platelet-rich plasma for repair of a short sciatic nerve defect in rats

Platelet-rich plasma containing various growth factors can promote nerve regeneration. An inside-out vein graft can substitute nerve autograft to repair short nerve defects. It is hypothesized that an inside-out vein graft filled with platelet-rich plasma shows better effects in the repair of short sciatic nerve defects. In this study, an inside-out vein autograft filled with platelet-rich plasma was used to bridge a 10 mm-long sciatic nerve defect in rats. The sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better improved than that of rats with a simple inside-out vein autograft. At 6 and 8 weeks, the sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better than that of rats undergoing nerve autografting. Compared with the sciatic nerve repaired with a simple inside-out vein autograft, the number of myelinated axons was higher, axon diameter and myelin sheath were greater in the sciatic nerve repaired with an inside-out vein autograft filled with platelet-rich plasma and they were similar to those in the sciatic nerve repaired with nerve autograft. These findings suggest that an inside-out vein graft filled with platelet-rich plasma can substitute nerve autograft to repair short sciatic nerve defects.

Immediate versus delayed primary nerve repair in the rabbit sciatic nerve

It is well known that peripheral nerve injury should be treated immediately in the clinic, but in some instances, repair can be delayed. This study investigated the effects of immediate versus delayed (3 days after injury) neurorrhaphy on repair of transected sciatic nerve in New Zealand rabbits using stereological, histomorphological and biomechanical methods. At 8 weeks after immediate and delayed neurorrhaphy, axon number and area in the sciatic nerve, myelin sheath and epineurium thickness, Schwann cell morphology, and the mechanical property of nerve fibers did not differ obviously. These results indicate that delayed neurorrhaphy do not produce any deleterious effect on sciatic nerve repair.

Platelet-rich plasma and the elimination of neuropathic pain

Peripheral neuropathic pain typically results from trauma-induced nociceptive neuron hyperexcitability and their spontaneous ectopic activity. This pain persists until the trauma-induced cascade of events runs its full course, which results in complete tissue repair, including the nociceptive neurons recovering their normal biophysical properties, ceasing to be hyperexcitable, and stopping having spontaneous electrical activity. However, if a wound undergoes no, insufficient, or too much inflammation, or if a wound becomes stuck in an inflammatory state, chronic neuropathic pain persists. Although various drugs and techniques provide temporary relief from chronic neuropathic pain, many have serious side effects, are not effective, none promotes the completion of the wound healing process, and none provides permanent pain relief. This paper examines the hypothesis that chronic neuropathic pain can be permanently eliminated by applying platelet-rich plasma to the site at which the pain originates, thereby triggering the complete cascade of events involved in normal wound repair. Many published papers claim that the clinical application of platelet-rich plasma to painful sites, such as muscle injuries and joints, or to the ends of nerves evoking chronic neuropathic pain, a process often referred to as prolotherapy, eliminates pain initiated at such sites. However, there is no published explanation of a possible mechanism/s by which platelet-rich plasma may accomplish this effect. This paper discusses the normal physiological cascade of trauma-induced events that lead to chronic neuropathic pain and its eventual elimination, techniques being studied to reduce or eliminate neuropathic pain, and how the application of platelet-rich plasma may lead to the permanent elimination of neuropathic pain. It concludes that platelet-rich plasma eliminates neuropathic pain primarily by platelet- and stem cell-released factors initiating the complex cascade of wound healing events, starting with the induction of enhanced inflammation and its complete resolution, followed by all the subsequent steps of tissue remodeling, wound repair and axon regeneration that result in the elimination of neuropathic pain, and also by some of these same factors acting directly on neurons to promote axon regeneration thereby eliminating neuropathic pain.

Effect of platelet-rich plasma in nerve regeneration after LASIK

PURPOSE

To investigate the effect of topical eye application of platelet-rich plasma (E-PRP) on the recovery of corneal sensitivity after LASIK and the anatomical recovery of the sub-basal corneal plexus as studied by confocal microscopy.

METHODS

This was a randomized, consecutive, controlled, prospective and masked study on 108 myopic eyes receiving LASIK. The main variables of the study were the increase in corneal sensitivity (Cochet-Bonet aesthesiometer; Luneau, Paris, France) and the aspect of the sub-basal nerve plexus (confocal microscope). Additionally, a biomicroscopic study of the epithelial status of the cornea and a subjective questionnaire were completed. Each eye of each patient was assigned to one of two groups: 54 eyes treated with balanced saline solution and 54 fellow eyes receiving PRP drops for 3 months.

RESULTS

No significant differences were detected when the corneal sensitivity thresholds were compared at any postoperative visit in both groups (P > .05 for all comparisons). Almost identical sub-basal fiber densities were estimated for both groups before LASIK (t test, P = .66). However, the type and severity of staining detected during the slit-lamp examinations at the first and third month postoperatively were significantly less evident in the E-PRP treatment group (Wilcoxon test, P < .05).

CONCLUSIONS

PRP drops have beneficial effects for promoting epithelial status after LASIK but have no positive effect on recovery of corneal sensitivity, probably due to the limited bioavailability of growth factors in corneal stroma when the substance is topically administered.

Application of two different hemostatic procedures during microsurgical median nerve reconstruction in the rat does not hinder axonal regeneration

BACKGROUND

Hemostatic procedures by means of electrical coagulation or application of topical agents are widely used to avoid postoperative bleeding during microsurgical reconstruction of peripheral nerves. It is speculated, however, that extensive hemostasis could provoke significant nerve damage.

OBJECTIVE

To examine the effects of 2 intraoperative hemostatic procedures on peripheral nerve regeneration.

METHODS

In 36 adult rats divided into 3 groups, the median nerve was transected and repaired by end-to-end neurorrhaphy. During surgery, bleeding was treated in groups 2 and 3 by application of either the topical hemostatic agent Floseal or routine bipolar coagulation. The degree of nerve regeneration was assessed in terms of motor function recovery using weekly grasping test evaluation for 3 months, muscle mass recovery of flexor digitorum sublimis, and stereological assessment of myelinated axon regeneration.

RESULTS

Neither of the 2 applied hemostatic methods induced any negative effects on nerve regeneration as defined by grip strength, muscle mass recovery, and morphology of myelinated nerve fibers. In contrast, Floseal-treated animals showed a faster progression of motor function recovery, and animals subjected to bipolar coagulation revealed a higher muscle mass recovery compared with the control group.

CONCLUSION

Controlled application of bipolar coagulation or Floseal does not exert a negative effect on the nerve regeneration outcome in rats. We propose that these methods can be applied safely to patients.

Neurological recovery across a 12-cm-long ulnar nerve gap repaired 3.25 years post trauma: case report

BACKGROUND AND IMPORTANCE

The standard clinical technique for repairing peripheral nerve gaps is the use of autologous sensory nerve grafts. The present study tested whether a collagen tube filled with autologous platelet-rich fibrin could induce sensory and motor recovery across a 12-cm nerve gap repaired 3.25 years post trauma, and reduce or eliminate neuropathic pain.

CLINICAL PRESENTATION

Two years postrepair, good ring and small finger motor function had developed that could generate 1 kg of force, and topographically correct 2-point discrimination and sensitivity to vibration in the small and ring finger and proximal but not distal wrist had developed. The patient's excruciating neuropathic pain was reduced to tolerable, and he avoided the indicated extremity amputation. The 12-cm-long nerve gap was bridged with a collagen tube filled with autologous platelet-rich fibrin.

CONCLUSION

We demonstrate that a conduit filled with platelet-rich fibrin can induce limited, but appropriate, sensory and motor recovery across a 12-cm nerve gap repaired 3.25 years post trauma, without sacrificing a sensory nerve, can reduce existing excruciating neuropathic pain to tolerable, and allow avoidance of an indicated upper-extremity amputation. We believe the technique can be improved to induce more extensive and reliable neurological recovery.

The effect of melatonin and platelet gel on sciatic nerve repair: an electrophysiological and stereological study

Nerve regeneration after surgical reconstruction is far from optimal, and thus effective strategies for improving the outcome of nerve repair are being sought. In this experiment, we verified if postoperative intraperitoneal melatonin (MLT) administration after intraoperative platelet gel application improves peripheral nerve regeneration. In adult male rats, 1-cm long sciatic nerve defects were repaired using four different strategies: autologous nerve graft repair followed by MLT (NM, n = 5), collagen conduit repair followed by MLT (CM, n = 5), platelet gel-enriched collagen conduit repair followed by MLT (CGM, n = 6), and platelet gel-enriched collagen conduit (CG, n = 5) repair followed by no substance administration. Sham operated animals were used as controls (Cont, n = 5). Ninety days after surgery, the nerve regeneration outcome was comparatively assessed by means of electrophysiological and stereological analysis. Electrophysiology revealed no significant differences between the experimental and the sham control groups. Stereological analysis showed no significant differences among the experimental groups regarding axon size and myelin thickness, but the axon number was significantly lower in the CM compared to Cont and NM group. Moreover, there was no significant difference between number of axons in CG and Cont groups, between CGM and CM, and between CM and NM. Although it was observed that platelet gel have a positive effect on nerve regeneration, but a combination of local platelet gel with MLT does not have the same effect on nerve repair.

Platelet-rich plasma: a promising product for treatment of peripheral nerve regeneration after nerve injury

Nerve regeneration includes regrowth of injured axons as well as myelination, restoration of synaptic connections and recovery of physiological functions. Platelet-rich plasma (PRP) is prepared from the patient's own blood and contains growth factors that influence wound healing and used in various surgical fields including oral and maxillofacial surgery. When platelets are activated either ex vivo or in vivo, growth factors and proteins were released from platelets' alpha granules. Recent studies proved that PRP could promote regeneration of injured peripheral nerve. This review focuses on current trials using PRP to promote nerve regeneration and repairment, and proposes potential clinical application of PRP for nerve injury in the future.

Functional and morphological assessment of a standardized crush injury of the rat median nerve

The availability of effective experimental models for investigating nerve regeneration and designing new strategies for promoting this unique repair process is important. The aim of this study was to standardize a rat median nerve crush injury model using a non-serrated clamp exerting a compression force of 17.02 MPa for a duration of 30s. Results showed that functional recovery, evaluated by grasping test, was already detectable at day-12 and progressively increased until day-28 after which animal performance plateaued until the end of testing (day-42), reaching a range of 75-80% of pre-operative values. Morphological analysis on the median nerve segments, distal to the crush lesion, which were withdrawn at the end of the experiment showed that regenerated nerve fibers are significantly more numerous and densely packed; they are also smaller and have a thinner myelin sheath compared to controls. Together, these results provide a baseline characterization of the crush median nerve injury experimental model for its employment in the investigation of nerve regeneration research, especially when a reproducible regeneration process is required, such as for the study of biological mechanisms of peripheral nerve fiber regeneration or development of new therapeutic agents for promoting posttraumatic nerve repair.