Distal Stump Research Articles

BDNF gene delivery mediated by neuron-targeted nanoparticles is neuroprotective in peripheral nerve injury.

Neuron-targeted gene delivery is a promising strategy to treat peripheral neuropathies. Here we propose the use of polymeric nanoparticles based on thiolated trimethyl chitosan (TMCSH) to mediate targeted gene delivery to peripheral neurons upon a peripheral and minimally invasive intramuscular administration. Nanoparticles were grafted with the non-toxic carboxylic fragment of the tetanus neurotoxin (HC) to allow neuron targeting and were explored to deliver a plasmid DNA encoding for the brain-derived neurotrophic factor (BDNF) in a peripheral nerve injury model. The TMCSH-HC/BDNF nanoparticle treatment promoted the release and significant expression of BDNF in neural tissues, which resulted in an enhanced functional recovery after injury as compared to control treatments (vehicle and non-targeted nanoparticles), associated with an improvement in key pro-regenerative events, namely, the increased expression of neurofilament and growth-associated protein GAP-43 in the injured nerves. Moreover, the targeted nanoparticle treatment was correlated with a significantly higher density of myelinated axons in the distal stump of injured nerves, as well as with preservation of unmyelinated axon density as compared with controls and a protective role in injury-denervated muscles, preventing them from denervation. These results highlight the potential of TMCSH-HC nanoparticles as non-viral gene carriers to deliver therapeutic genes into the peripheral neurons and thus, pave the way for their use as an effective therapeutic intervention for peripheral neuropathies.

Supinator to ulnar nerve transfer via in situ anterior interosseous nerve bridge to restore intrinsic muscle function in combined proximal median and ulnar nerve injury: a novel cadaveric study

BackgroundIn cases of high ulnar nerve palsy, result of nerve repair in term of intrinsic muscle recovery is unsatisfactory. Distal nerve transfer can diminish the regeneration time and improve the results. But, there was no perfect distal nerve transfer for restoring intrinsic hand function in combined proximal median and ulnar nerve injuries. This cadaveric study aims to evaluate the possibility and feasibility of supinator nerve transfer to motor branch of ulnar nerve (MUN). MethodsTen cadaveric upper limbs dissected to identify the location of the supinator branch, anterior interosseous nerve (AIN), and MUN. The AIN was cut from its origin and transferred to the supinator branches. Also, the AIN was distally cut and transferred to the MUN. After nerve coaptation, surface area, fascicle count, and axon number were determined by histologic methods. ResultsIn all limbs, the proximal and distal stumps of AIN reached the supinator branch and the MUN without tension, respectively. The mean of axon number in the supinator, proximal stump of AIN, distal stump of AIN and MUN branches were 32,426, 45,542, 25,288, and 35,426, respectively. ConclusionsThis study showed that transfer of the supinator branches to the MUN is possible via the in situ AIN bridge. The axon count data showed a favorable match between the supinator branches, AIN, and MUN. Therefore, it is suggested that this technique can be useful for patients with combined high median and ulnar nerve injuries.

Ingenuity Pathway Analysis of Gene Expression Profiles in Distal Nerve Stump following Nerve Injury: Insights into Wallerian Degeneration.

Nerve injury is a common and difficult clinical problem worldwide with a high disability rate. Different from the central nervous system, the peripheral nervous system is able to regenerate after injury. Wallerian degeneration in the distal nerve stump contributes to the construction of a permissible microenvironment for peripheral nerve regeneration. To gain new molecular insights into Wallerian degeneration, this study aimed to identify differentially expressed genes and elucidate significantly involved pathways and cellular functions in the distal nerve stump following nerve injury. Microarray analysis showed that a few genes were differentially expressed at 0.5 and 1 h post nerve injury and later on a relatively larger number of genes were up-regulated or down-regulated. Ingenuity pathway analysis indicated that inflammation and immune response, cytokine signaling, cellular growth and movement, as well as tissue development and function were significantly activated following sciatic nerve injury. Notably, a cellular function highly related to nerve regeneration, which is called Nervous System Development and Function, was continuously activated from 4 days until 4 weeks post injury. Our results may provide further understanding of Wallerian degeneration from a genetic perspective, thus aiding the development of potential therapies for peripheral nerve injury.

A novel therapy to promote axonal fusion in human digital nerves.

Peripheral nerve injury can have a devastating impact on our military and veteran population. Current strategies for peripheral nerve repair include techniques such as nerve tubes, nerve grafts, tissue matrices, and nerve growth guides to enhance the number of regenerating axons. Even with such advanced techniques, it takes months to regain function. In animal models, polyethylene glycol (PEG) therapy has shown to improve both physiologic and behavioral outcomes after nerve transection by fusion of a portion of the proximal axons to the distal axon stumps. The objective of this study was to show the efficacy of PEG fusion in humans and to retrospectively compare PEG fusion to standard nerve repair. Patients with traumatic lacerations involving digital nerves were treated with PEG after standard microsurgical neurorrhaphy. Sensory assessment after injury was performed at 1 week, 2 weeks, 1 month, and 2 months using static two-point discrimination and Semmes-Weinstein monofilament testing. The Medical Research Council Classification (MRCC) for Sensory Recovery Scale was used to evaluate the level of injury. The PEG fusion group was compared to patient-matched controls whose data were retrospectively collected. Four PEG fusions were performed on four nerve transections in two patients. Polyethylene glycol therapy improves functional outcomes and speed of nerve recovery in clinical setting assessed by average MRCC score in week 1 (2.8 vs 1.0, p = 0.03). At 4 weeks, MRCC remained superior in the PEG fusion group (3.8 vs 1.3, p = 0.01). At 8 weeks, there was improvement in both groups with the PEG fusion cohort remaining statistically better (4.0 vs 1.7, p = 0.01). Polyethylene glycol fusion is a novel therapy for peripheral nerve repair with proven effectiveness in animal models. Clinical studies are still in early stages but have had encouraging results. Polyethylene glycol fusion is a potential revolutionary therapy in peripheral nerve repair but needs further investigation. Therapeutic study, level IV.

Giant mucocele of the colon at the distal stump due to low-grade mucinous neoplasia.

We present the first ever report on a colonic mucocele observed at the distal stump of a transverse loop colostomy caused by neoplasia. A 37-year-old female consulted us because of abdominal pain and vomiting caused by cystic lesions in the upper left abdominal quadrant. A preoperative checkup revealed no sign of neoplastic lesions; however, tumor resection was performed because of the symptoms. The tumor was a mucocele of the distal stump of the transverse colon with obstruction interposed between the mucocele and stoma. Pathological diagnosis was low-grade adenoma; however, it appeared like low-grade mucinous neoplasia of the appendix rather than a normal colonic adenoma. The neoplasia existed in the transitional segment between obstruction and dilatation. As this is the first case of colonic mucocele caused by mucinous neoplasia, no definite consensus for diagnosis and treatment exists. With reference to low-grade mucinous neoplasia, we propose that complete surgical resection be performed for diagnosis and a favorable outcome.

The Present and Future for Peripheral Nerve Regeneration.

Peripheral nerve injury can have a potentially devastating impact on a patient's quality of life, resulting in severe disability with substantial social and personal cost. Refined microsurgical techniques, advances in peripheral nerve topography, and a better understanding of the pathophysiology and molecular basis of nerve injury have all led to a decisive leap forward in the field of translational neurophysiology. Nerve repair, nerve grafting, and nerve transfers have improved significantly with consistently better functional outcomes. Direct nerve repair with epineural microsutures is still the surgical treatment of choice when a tension-free coaptation in a well-vascularized bed can be achieved. In the presence of a significant gap (>2-3 cm) between the proximal and distal nerve stumps, primary end-to-end nerve repair often is not possible; in these cases, nerve grafting is the treatment of choice. Indications for nerve transfer include brachial plexus injuries, especially avulsion type, with long distance from target motor end plates, delayed presentation, segmental loss of nerve function, and broad zone of injury with dense scarring. Current experimental research in peripheral nerve regeneration aims to accelerate the process of regeneration using pharmacologic agents, bioengineering of sophisticated nerve conduits, pluripotent stem cells, and gene therapy. Several small molecules, peptides, hormones, neurotoxins, and growth factors have been studied to improve and accelerate nerve repair and regeneration by reducing neuronal death and promoting axonal outgrowth. Targeting specific steps in molecular pathways also allows for purposeful pharmacologic intervention, potentially leading to a better functional recovery after nerve injury. This article summarizes the principles of nerve repair and the current concepts of peripheral nerve regeneration research, as well as future perspectives. [Orthopedics. 2017; 40(1):e141-e156.].

Regeneration patterns influence hindlimb automutilation after sciatic nerve repair using stem cells in rats

IntroductionHindlimb autophagy is common after rat sciatic total axotomy and is considered as a sign of neuropathic pain. We applied adult stem cells in a fibrin conduit in a total sciatic axotomy model to improve nerve regeneration, investigating whether a correlation could be detected between stem cells effects on regeneration and limb autophagy. Material and MethodsAfter sciatic nerve section, a 1-cm sciatic gap was crossed using fibrin conduits. Experimental groups included empty fibrin conduits, fibrin conduits seeded with primary Schwann cells, and fibrin conduits seeded with Schwann cell-like differentiated mesenchymal or adipose-derived stem cells (dMSCs and dASCs). Controls were represented by autografts and by sham rats (tot n=34). At 16 weeks post-implantation, regeneration pattern was analysed on histological sections and related to eventual autophagy. Hindlimbs were evaluated and scored according to autophagy Wall’s scale and X-Rays radiological evaluation. ResultsAll regenerative cell lines significantly improved myelination at the mid conduit level, compared to the empty tubes. However, dMSC could not significantly improve myelination at the distal stump, showing a more chaotic regeneration compared to both other cells groups and controls. Autophagy was correlated to this regeneration patterns, with higher autophagy scores in the empty and dMSC group. ConclusionHindlimb autophagy can be used as index of neuropathic pain due to nerve lesion or on-going immature regeneration. dMSC group was characterized by a less targeted regeneration comparing to dASC and primary Schwann cells, which confirmed their effectiveness in regeneration and potential in future clinical applications.

Olfactory ensheathing glia cell therapy and tubular conduit enhance nerve regeneration after mouse sciatic nerve transection

The regenerative potential of the peripheral nervous system (PNS) is widely known, but functional recovery, particularly in humans, is seldom complete. Therefore, it is necessary to resort to strategies that induce or potentiate the PNS regeneration. Our main objective was to test the effectiveness of Olfactory Ensheathing Cells (OEC) transplantation into a biodegradable conduit as a therapeutic strategy to improve the repair outcome after nerve injury. Sciatic nerve transection was performed in C57BL/6 mice; proximal and distal stumps of the nerve were sutured into the collagen conduit. Two groups were analyzed: DMEM (acellular grafts) and OEC (1×105/2μL). Locomotor function was assessed weekly by Sciatic Function Index (SFI) and Global Mobility Test (GMT). After eight weeks the sciatic nerve was dissected for morphological analysis. Our results showed that the OEC group exhibited many clusters of regenerated nerve fibers, a higher number of myelinated fibers and myelin area compared to DMEM group. The G-ratio analysis of the OEC group showed significantly more fibers on the most suitable sciatic nerve G-ratio index. Motor recovery was accelerated in the OEC group. These data provide evidence that the OEC therapy can improve sciatic nerve functional and morphological recovery and can be potentially translated to the clinical setting.

Development of a decellularization method to produce nerve allografts using less invasive detergents and hyper/hypotonic solutions

Here, we describe a novel method of processing decellularized nerve grafts using osmotic effects of hypotonic and hypertonic solutions and Triton X-100 (a nonionic detergent) and CHAPS (an amphoteric detergent). To evaluate decellularization, the devised method and Hudson's method were compared with respect to remaining cellular components (as assessed by H&E staining and S-100 immunoreactivity) and extracellular matrix structural integrity (as assessed by H&E staining and laminin immunoreactivity) by using rat sciatic nerves. In addition, a 1.5-cm sciatic nerve gap rat model was treated by implanting decellularized nerve grafts prepared using the devised method, Hudson's method, or an autograft to evaluate nerve regeneration. Nerve histomorphometry of distal stumps and wet muscle mass were evaluated at 12 weeks after implantation. The devised method produced outcomes similar to those of Hudson's method in terms of cellular component removal, but the devised method was significantly better in terms of ECM preservation. Histomorphometric study showed that the devised method produced significantly fewer nerve fiber and axonal densities than autografting, but much more than Hudson's method. The wet muscle mass of the devised method was also significantly lower than that of autografting, but much higher than that of Hudson's method. The described process for producing decellularized nerve grafts yielded better outcomes with respect to peripheral nerve regeneration than the established ionic detergent-based methods in a rat model. This study indicates that decellularized nerve grafts produced in this manner show favorable nerve regeneration used for bridging nerve gaps.

Nonconventional Tendon Advance for Injuries in Zones 1 and 2

Objective: Two techniques for reconstruction of tendon flexor injuries in zones 1 and 2 of Verdan in which primary suture cannot take place are presented. These techniques consists in carrying out a zetaplasty of the injured tendon in zone 5 to slide the proximal stump of the original rupture toward the distal stump of the tendon, suture both stump, and then perform the suture of the zetaplasty with the required tension. Another option, in case the end to end suture is unable, is to suture the lengthened tendon to an uninjured superficial flexor tendon. Methods: Thirteen patients with an average of 29 years of age were operated on with these two techniques. Diagnoses included 3 failures in primary suture of profundus flexor tendon, 7 tendon injuries treated 4 weeks after the trauma, and 3 injuries with shortening of the distal stump greater than 3 cm. In 7 cases, zetaplasty was performed with an end to end suture of the same flexor tendon, and in the remaining 6 zetaplasty was carried out with a suture of the proximal stump to an uninjured flexor tendon. Results: Average follow-up was 17.23 months. Assessment with the Strickand’s evaluation system yielded the following results: 8 excellent, 4 good, and 1 poor. Conclusions: The encouraging results in the short term with these techniques of shorter operating time and less surgical requirement motivate further development. A larger number of cases are necessary to obtain more reliable conclusions about their advantages and side effects.

Clinical Study of Sensory Recovery of Artificial Nerve Grafts (Nerbridge®)

Purpose: To examine postoperative sensory recovery of patients who used Nerbridge® for sensory nerves, and the indications. Subjects and methods: We investigated length of the transplanted nerve, postoperative sensory evaluation, and Disabilities of Arm, Shoulder and Hand (DASH) score in patients who underwent surgery at our center and could be followed up for at least 6 months. The participants were 11 patients (8 men and 3 women) with 17 nerves for study whose mean age at the time of injury was 48 years (15-64 years) and mean follow-up period was 14.4 months (6-28 months). We used the Semmes Weinstein (SW) test for postoperative sensory evaluation. Results: Mean length of the transplanted nerve was 17.3 mm (3-41 mm); the sensory evaluation had 8 patients in the blue range, 6 in the purple range, and 3 in the red range; and the mean DASH score was 16.3 points (1.7-37.5 points). The results tended to be unfavorable for patients with severe injuries such as an amputated finger and those with relatively long transplanted nerves. The results of this study indicated that Nerbridge® worked well with digital nerve deficits on the order of 20 mm. Discussion: When the results following artificial nerve transplants were as good as or better than nerve autografts, the donor site was not problematic and the transplantations with artificial nerves were clearly useful. The product would be decomposed and absorbed in vivo in approximately 3 months. Although the product can be used for a maximum length of 50 mm, in a deficit over 30 mm, the regenerating nerve might be metabolized before reaching its distal nerve stump; thus, a nerve autograft would be preferred in that situation.

Chitosan crosslinked flat scaffolds for peripheral nerve regeneration

Chitosan (CS) has been widely used in a variety of biomedical applications, including peripheral nerve repair, due to its excellent biocompatibility, biodegradability, readily availability and antibacterial activity. In this study, CS flat membranes, crosslinked with dibasic sodium phosphate (DSP) alone (CS/DSP) or in association with the γ-glycidoxypropyltrimethoxysilane (CS/GPTMS_DSP), were fabricated with a solvent casting technique. The constituent ratio of crosslinking agents and CS were previously selected to obtain a composite material having both adequate mechanical properties and high biocompatibility.In vitro cytotoxicity tests showed that both CS membranes allowed cell survival and proliferation. Moreover, CS/GPTMS_DSP membranes promoted cell adhesion, induced Schwann cell-like morphology and supported neurite outgrowth from dorsal root ganglia explants.Preliminary in vivo tests carried out on both types of nerve scaffolds (CS/DSP and CS/GPTMS_DSP membranes) demonstrated their potential for: (i) protecting, as a membrane, the site of nerve crush or repair by end-to-end surgery and avoiding post-operative nerve adhesion; (ii) bridging, as a conduit, the two nerve stumps after a severe peripheral nerve lesion with substance loss.A 1 cm gap on rat median nerve was repaired using CS/DSP and CS/GPTMS_DSP conduits to further investigate their ability to induce nerve regeneration in vivo. CS/GPTMS_DSP tubes resulted to be more fragile during suturing and, along a 12 week post-operative lapse of time, they detached from the distal nerve stump. On the contrary CS/DSP conduits promoted nerve fiber regeneration and functional recovery, leading to an outcome comparable to median nerve repaired by autograft.

Dynamic Ultrasonography During Nonoperative Treatment following Achilles Tendon Rupture

Category: Ankle Introduction/Purpose: Many recent studies suggest similar outcome and rerupture rates between operative and nonoperative treatment with accelerated rehabilitation for acute Achilles tendon rupture. Nevertheless, it is very difficult for surgeons who have traditionally been performing surgery for Achilles tendon rupture to adopt nonoperative treatment. Unlike fracture healing, surgeons cannot confirm the amount of tendon healing with plain radiography to begin accelerated rehabilitation. The aim of the present study was to determine visually the amount of Achilles tendon healing with dynamic ultrasonography and therefore aid in surgeons decision-making process during nonoperative treatment following Achilles tendon rupture. Methods: Thirty-one patients with acute Achilles rupture were included in the study. The mean age at the time of rupture was 42 years. There were 32 male and 10 females. Ultrasonographic evaluation was performed at the time of initial diagnosis, and at 2, 3, 5, 7, 10, 13 weeks after injury. Initially the amount of gap with ankle in neutral position was measured, then the amount of tendon healing(continuity) was measured during the follow-up. Results: Initially, the mean gap was 13 mm with ankle neutral, then the mean gap was reduced to 3 mm with maximum ankle plantarflexion. At 3 weeks, proximal stump motion was confirmed with mean gap of less than 2 mm during passive ankle motion from maximum plantarflexion to neutral in all patients, indicating that tendon healing began between the distal and proximal stumps. Yet, there were no definitely visible continuity between the two stumps. At 5 weeks, 30% of entire tendon width showed continuity, 50% at 7 weeks, 70% at 10 weeks, and the entire tendon healed at 13 weeks. Clinically, all patients returned to previous activities of daily living without any complications at the final follow-up. Conclusion: Surgeons beginning to adopt nonoperative treatment for acute Achilles tendon rupture may safely remove the cast or orthosis at three weeks after injury for gradual increase in ankle range of motion and to reduce patient disability.

Electrical muscle stimulation elevates intramuscular BDNF and GDNF mRNA following peripheral nerve injury and repair in rats

Despite advances in surgery, patients with nerve injuries frequently have functional deficits. We previously demonstrated in a rat model that daily electrical muscle stimulation (EMS) following peripheral nerve injury and repair enhances reinnervation, detectable as early as two weeks post-injury. In this study, we explain the enhanced early reinnervation observed with electrical stimulation. In two groups of rats, the tibial nerve was transected and immediately repaired. Gastrocnemius muscles were implanted with intramuscular electrodes for sham or muscle stimulation. Muscles were stimulated daily, eliciting 600 contractions for one hour/day, repeated five days per week. Sixteen days following nerve injury, muscles were assessed for functional reinnervation by motor unit number estimation methods using electromyographic recording. In a separate cohort of rats, surgical and electrical stimulation procedures were identical but muscles and distal nerve stumps were harvested for molecular analysis. We observed that stimulated muscles had significantly higher motor unit number counts. Intramuscular levels of brain-derived and glial cell line-derived neurotrophic factor (BDNF and GDNF) mRNA were significantly upregulated in muscles that underwent daily electrical stimulation compared to those without stimulation. The corresponding levels of trophic factor mRNA within the distal stump were not different from one another, indicating that the intramuscular electrical stimulus does not modulate Schwann cell-derived trophic factor transcription. Stimulation over a three-month period maintained elevated muscle-derived GDNF but not BDNF mRNA. In conclusion, EMS elevates intramuscular trophic factor mRNA levels which may explain how EMS enhances neural regeneration following nerve injury.

DTI metrics can be used as biomarkers to determine the therapeutic effect of stem cells in acute peripheral nerve injury.

To determine the role of diffusion tensor imaging (DTI) metrics as biomarkers for the therapeutic effects of mesenchymal stem cells (MSCs) in acute peripheral nerve injury. Forty-four adult rats received subepineurial microinjection of MSCs (n = 22) or phosphate buffered saline (PBS, n = 22) 1 week after the sciatic nerve trunk crush injury. Sequential fat-suppressed T2-weighted imaging, T2 measurement, DTI and sciatic nerve functional assessment were performed at a 3.0 Tesla MR unit over an 8-week follow-up, with histological assessments performed at regular intervals. The sciatic nerve function index, T2 value, and DTI metrics, including fractional anisotropy (FA), axial diffusivity, radial diffusivity (RD), and mean diffusivity values of the distal stumps of crushed nerves were measured and compared between the two groups. Nerves treated with MSCs showed better functional recovery and exhibited more pronounced nerve regeneration compared with nerves treated with PBS. T2 values in nerves treated with MSCs or PBS showed a similar change pattern (P = 0.174), while FA and RD values in nerves treated with MSCs showed more rapid return (one week earlier) to baseline level than nerves treated with PBS (P = 0.045; 0.035). Nerves treated with MSCs had higher FA and lower RD values than nerves treated with PBS during the period from 2 to 3 weeks after surgery (P ≤ 0.0001, 0.004; P = 0.004, 0.006). FA and RD values derived from DTI might be used as sensitive biomarkers for detecting the therapeutic effect of stem cells in acute peripheral nerve crush injuries. 2 J. Magn. Reson. Imaging 2017;45:855-862.

Can mammalian vision be restored following optic nerve degeneration?

Can mammalian vision be restored following optic nerve degeneration? Damien P Kuffler Institute of Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico Abstract: For most adult vertebrates, glaucoma, trauma, and tumors close to retinal ganglion cells (RGCs) result in their neuron death and no possibility of vision reestablishment. For more distant traumas, RGCs survive, but their axons do not regenerate into the distal nerve stump due to regeneration-inhibiting factors and absence of regeneration-promoting factors. The annual clinical incidence of blindness in the United States is 1:28 (4%) for persons >40 years, with the total number of blind people approaching 1.6 million. Thus, failure of optic nerves to regenerate is a significant problem. However, following transection of the optic nerve of adult amphibians and fish, the RGCs survive and their axons regenerate through the distal optic nerve stump and reestablish appropriate functional retinotopic connections and fully functional vision. This is because they lack factors that inhibit axon regeneration and possess factors that promote regeneration. The axon regeneration in lower vertebrates has led to extensive studies by using them as models in studies that attempt to understand the mechanisms by which axon regeneration is promoted, so that these mechanisms might be applied to higher vertebrates for restoring vision. Although many techniques have been tested, their successes have varied greatly from the recovery of light and dark perceptions to partial restoration of the optomotor response, depth perception, and circadian photoentrainment, thus demonstrating the feasibility of reconstructing central circuitry for vision after optic nerve damage in mature mammals. Thus, further research is required to induce the restoration of vision in higher vertebrates. This paper examines the causes of vision loss and techniques that promote transected optic nerve axons to regenerate and reestablish functional vision, with a focus on approaches that may have clinical applicability. Keywords: vision, RGC, axon regeneration, optic nerve trauma, restoration of vision

Can the Babysitter Procedure Improve Nerve Regeneration and Denervated Muscle Atrophy in the Treatment of Peripheral Nerve Injury?

The authors evaluated the long-term efficacy of the "babysitter" procedure in improving nerve regeneration and denervated muscle atrophy for peripheral nerve repair. Eighty Lewis rats were allocated equally into four groups. The peroneal nerves of all animals were divided. In group A, the peroneal nerve stumps were anchored into adjacent muscles. Rats in group B underwent end-to-end neurorrhaphy. Rats in group C underwent end-to-side neurorrhaphy of the distal peroneal nerve stump to an epineurial window on the tibial nerve. Rats in group D underwent end-to-side neurorrhaphy of the distal stump to the tibial nerve with 40 percent neurectomy. After 8 weeks, end-to-end neurorrhaphy of the peroneal nerve stumps was performed in group A, C, and D during a second-stage procedure. Electrophysiology, myelinated fiber counts, muscle force and weight, and muscle histomorphometry were analyzed at 4, 8, 12, and 24 weeks postoperatively. At 4 weeks, the end-to-end group showed predominant advantages in nerve regeneration and muscle preservation. No differences were observed in the latency delaying rate, tetanic tension, myelinated fiber number, or muscle weight between groups B and D by 24 weeks (p > 0.05). At 24 weeks, the results revealed superior latency delaying rate, myelinated axon regeneration, and size of muscle fibers in group D as compared with group C. Peripheral nerve repair with an initial motor nerve babysitter with 40 percent neurectomy of the donor nerve can achieve high efficacy in functional and structural recovery of the recipient system. Nerve babysitter by motor nerve with an epineural window was less effective.

Total Phallic Reconstruction Using the Radial Artery Based Forearm Free Flap After Traumatic Penile Amputation

IntroductionAlthough genital injuries in civilian centers are rare, the scenario is completely different in the battlefield. If the penile distal stump is not adequate for primary reimplantation or it cannot be found, then delayed penile reconstruction needs to be considered. AimTo report a single-center experience with total phallic reconstruction using radial artery based forearm free flap (RAFFF) after penile traumatic loss. MethodsWe retrospectively reviewed the clinical records of 10 patients who underwent total phallic reconstruction with the use of the RAFFF from September 2001 through August 2015 after traumatic amputation of the penis. Main Outcome MeasuresPatients' baseline features, surgical outcomes, complications, and satisfaction are reported. ResultsThe average age at the time of penile reconstruction was 36 years (range = 27–52 years). The causes of penile loss were self-amputation owing to an acute schizophrenic episode (n = 2), road traffic accident (n = 3), blast injury (n = 3), donkey bite (n = 1), and Fournier gangrene (n = 1). The average time from the trauma to reconstruction with the RAFFF was 7 years (range = 2–15 years). The urethral stump was adequate for primary anastomosis, with phallic neourethra construction in six patients. The remaining patients had complete avulsion of the penis and were voiding though a perineal urethrostomy. In consequence, they required a two-stage urethroplasty. An acute arterial thrombosis of the microsurgical anastomosis occurred in two patients and was managed successfully with immediate exploration. A neourethra stricture and fistula occurred in one patient, which needed revision. All patients who underwent complete urethral reconstruction could void and ejaculate from the tip of the phallus. After a median follow-up of 51 months (range = 1–114 months), all patients were satisfied with the size, cosmetic appearance, and sensation of the phallus. Six patients underwent inflatable penile prosthesis implantation and could engage in penetrative sex. However, revision surgery was needed in three patients (infection, n = 2; mechanical failure, n = 1). ConclusionDespite the high incidence of postoperative complications and the possible need for multiple operations, in expert hands and in large-volume centers, penile reconstruction with the RAFFF after traumatic loss of the penis yields excellent results and allows patients to regain sexual and urinary functions.

Murine supraspinatus tendon injury model to identify the cellular origins of rotator cuff healing

ABSTRACTPurpose of this study: To elucidate the origin of cell populations that contribute to rotator cuff healing, we developed a mouse surgical model where a full-thickness, central detachment is created in the supraspinatus. Materials and methods: Three different inducible Cre transgenic mice with Ai9-tdTomato reporter expression (PRG4-9, αSMA-9, and AGC-9) were used to label different cell populations in the shoulder. The defect was created surgically in the supraspinatus. The mice were injected with tamoxifen at surgery to label the cells and sacrificed at 1, 2, and 5 weeks postoperatively. Frozen sections were fluorescently imaged then stained with Toluidine Blue and re-imaged. Results: Three notable changes were apparent postoperatively. (1) A long thin layer of tissue formed on the bursal side overlying the supraspinatus tendon. (2) The tendon proximal to the defect initially became hypercellular and disorganized. (3) The distal stump at the insertion underwent minimal remodeling. In the uninjured shoulder, tdTomato expression was seen in the tendon midsubstance and paratenon cell on the bursal side in PRG4-9, in paratenon, blood vessels, and periosteum of acromion in SMA-9, and in articular cartilage, unmineralized fibrocartilage of supraspinatus enthesis, and acromioclavicular joint in AGC-9 mice. In the injured PRG4-9 and SMA-9 mice, the healing tissues contained an abundant number of tdTomato+ cells, while minimal contribution of tdTomato+ cells was seen in AGC-9 mice. Conclusions: The study supports the importance of the bursal side of the tendon to rotator cuff healing and PRG4 and αSMA may be markers for these progenitor cells.

ErbB2 blockade with Herceptin (trastuzumab) enhances peripheral nerve regeneration after repair of acute or chronic peripheral nerve injury.

Attenuation of the growth supportive environment within the distal nerve stump after delayed peripheral nerve repair profoundly limits nerve regeneration. Levels of the potent Schwann cell mitogen neuregulin and its receptor ErbB2 decline during this period, but the regenerative impact of this change is not completely understood. Herein, the ErbB2 receptor pathway is inhibited with the selective monoclonal antibody Herceptin (trastuzumab) to determine its significance in regulating acute and chronic regeneration in a rat hindlimb. The common peroneal nerve of Sprague-Dawley rats was transected and repaired immediately or after 4 months of chronic denervation, followed by administration of Herceptin or saline solution. Regenerated motor and sensory neurons were counted using a retrograde tracer 1, 2, or 4, weeks after repair. Distal myelinated axon outgrowth after 4 weeks was quantified using histomorphometry. Immunofluorescent imaging was used to evaluate Schwann cell proliferation and epidermal growth factor receptor (EGFR) activation in the regenerating nerves. Herceptin administration increased the rate of motor and sensory neuron regeneration and the number of proliferating Schwann cells in the distal stump after the first week. Herceptin also increased the number of myelinated axons that regenerated 4 weeks after immediate and delayed repair. Reduced EGFR activation was observed using immunofluorescent imaging. Inhibition of the ErbB2 receptor with Herceptin unexpectedly enhances nerve regeneration after acute and delayed nerve repair. This finding raises the possibility of using targeted molecular therapies to improve outcomes of peripheral nerve injuries. The mechanism may involve a novel inhibitory association between ErbB2 and EGFR. Ann Neurol 2016;80:112-126.