Distal End Of Nerve Research Articles

Quantitative mass spectrometry analysis of the injured proximal and distal human digital nerve ends.

Proteomic analysis of injured human peripheral nerves, particularly focusing on events occurring in the proximal and distal nerve ends, remains relatively underexplored. This study aimed to investigate the molecular patterns underlying a digital nerve injury, focusing on differences in protein expression between the proximal and distal nerve ends. A total of 26 human injured digital nerve samples (24 men; 2 women; median age 47 [30-66] years), harvested during primary nerve repair within 48 h post-injury from proximal and distal nerve ends, were analyzed using mass spectrometry. A total of 3,914 proteins were identified, with 127 proteins showing significant differences in abundance between the proximal and the distal nerve ends. The downregulation of proteins in the distal nerve end was associated with synaptic transmission, autophagy, neurotransmitter regulation, cell adhesion and migration. Conversely, proteins upregulated in the distal nerve end were implicated in cellular stress response, neuromuscular junction stability and muscle contraction, neuronal excitability and neurotransmitter release, synaptic vesicle recycling and axon guidance and angiogenesis. Investigation of proteins, with functional annotations analysis, in proximal and the distal ends of human injured digital nerves, revealed dynamic cellular responses aimed at promoting tissue degeneration and restoration, while suppressing non-essential processes.

Vascular read-out for TRP channel functionality on distal peripheral nerve endings in healthy men

BackgroundQuantification of the vasodilation after topical application of capsaicin or cinnamaldehyde is often implemented to indirectly assess Transient Receptor Potential (TRP) Vanilloid 1 (TRPV1) or Ankyrin 1 (TRPA1) functionality respectively. This method has been well-established on the human forearm. However, to enable TRP functionality assessments in distal peripheral neuropathy, the vascular response upon TRP activation on dorsal finger skin was characterized. MethodsTwo doses of cinnamaldehyde (3 % and 10 % v/v) and capsaicin (300 μg and 1000 μg) were topically applied (20 μL) on the skin of the mid three proximal phalanges in 17 healthy men. The dose-response, and inter-hand and inter-period reproducibility of the dermal blood flow (DBF) increase was assessed using Laser Speckle Contrast Imaging (LSCI) during 60 min post-application. Linear mixed models explored dose-driven differences, whereas the intra-class correlation coefficient (ICC) estimated the reproducibility of the vascular response. ResultsBoth doses of cinnamaldehyde and capsaicin induced a robust, dose-dependent increase in DBF. The vascular response to cinnamaldehyde 10 % on finger skin, expressed as area under the curve, correlated well over time (ICC = 0.66) and excellently between hands (ICC = 0.87). Similarly, the response to capsaicin 1000 μg correlated moderately over time (ICC = 0.50) and well between hands (ICC = 0.73). ConclusionThe vascular response upon topical cinnamaldehyde and capsaicin application on finger skin is an alternative approach for measurements on forearm skin. Thereby, it is a promising vascular read-out to investigate the pathophysiology, and TRP involvement in particular, of specific peripheral neuropathic pain syndromes.

Skin biopsy reveals generalized small fibre neuropathy in hypermobile Ehlers-Danlos syndromes.

Ehlers-Danlos syndromes are hereditary disorders of connective tissue that are characterized by joint hypermobility, skin hyperextensibility and tissue fragility. The most common subtype is the hypermobile type. In addition to symptoms of small fibre neuropathy (SFN) due to damage to the small peripheral nerve fibres, with degeneration of the distal nerve endings, autonomic disorders such as postural tachycardia syndrome (PoTS) are frequently reported features in patients with hypermobile Ehlers-Danlos syndrome (hEDS). To date, the underlying pathophysiological mechanisms are still not completely understood. To better understand pathophysiological mechanisms of small fiber neuropathy and autonomic neuropathy in hypermobile Ehlers-Danlos Syndromes. We prospectively investigated 31 patients with hEDS compared to 31 healthy controls by using skin biopsy, quantitative sensory testing, tilt-table testing, the painDetect, Small Fibre Neuropathy Screening List and the COMPASS-31 (Composite Autonomic Symptom Score 31) questionnaire. Nineteen (61%) patients with hEDS were diagnosed with SFN, and 10 (32%) fulfilled the criteria for PoTS. Patients with hEDS had significantly higher heart rates than controls. According to quantitative sensory testing, these patients had generalized thermal and tactile hypesthesia. Skin biopsy revealed significantly reduced intraepithelial nerve fibre density proximally (thigh) and distally (lower leg) in patients compared to controls. This was consistent with various complaints of pain and sensory disturbances in both the proximal and distal body regions. These results confirm histologically proven SFN as a common feature in patients with hEDS, revealing a generalized distribution of nerve fibre loss. Regarding the frequently reported autonomic and neuropathic dysfunctions, the findings support SFN as an important, but not the only, underlying pathomechanism.

Neuroinflammation and сhemotherapy-induced peripheral neuropathy

Neurotoxicity is one of the common side effects of anticancer chemotherapy. This pathology has a detectability of 38–90%. In some cases, it causes not only a significant decrease of life quality but also decrease of dose of cytostatics. Therefore, the tasks of early diagnosis, prevention and treatment of neurotoxicity are very relevant. Sensors underlying detection, especially neuroinflammation processes, are needed to develop an effective therapy for chemotherapy-induced neurotoxicity. The purpose of this topic is to study the results of chemotherapy studies on changes in the activity of proinflammatory cytokines. In this regard, the study of behavioral societies in neuropathic pain in animal models is of great importance. It was revealed that various manifestations of inflammation of pro-inflammatory cytokines, chemokines, damage to the dorsal ganglion or distal nerve endings are increasingly being detected. Detection of chemically induced peripheral neuropathy using animal models is necessary for in-depth identification of the cause-and-effect mechanisms of its development and selection of new, more effective methods of treatment.

A Photosealed Cap Prevents Disorganized Axonal Regeneration and Neuroma following Nerve Transection in Rats

Background:Neuroma is a common sequela of traumatic peripheral nerve injury that can result in pain and decreased quality of life for patients. Neuromas result from axonal outgrowth in an attempt to reestablish continuity with the disrupted distal nerve end. Photosealing is a light-activated technique whereby tissues can be securely isolated in a strong and secure manner. This study investigated whether photosealing of autologous vein and crosslinked human amniotic membrane (xHAM) to cap the proximal stump of transected sciatic nerve would prevent disorganized axonal regeneration and neuroma in a rat model.Methods:The right sciatic nerve of Lewis rats (n = 27, 300–350 g) was transected 1 cm proximal to the trifurcation. Animals were randomized to one of three groups (n = 9): no further intervention (Group 1), photosealing with xHAM (Group 2), or photosealing with vein (Group 3). After 60 days, rats were euthanized and their right hindlimbs were re-explored for evidence of disorganized axonal regeneration and/or bulbous neuroma.Results:All untreated control animals were found to have protruding nerve fibers, often invading the adjacent muscle, and 33% of these control animals exhibited a bulbous neuroma. Photosealing with xHAM successfully capped 100% of nerves, with no observable axonal outgrowth. Photosealing with vein prevented axonal outgrowth in eight of nine nerves. No bulbous neuroma was found in any photosealed nerves.Conclusion:Nerve capping with photosealed xHAM or autologous vein can prevent axonal outgrowth in transected nerves, therefore decreasing the likelihood of symptomatic neuroma formation following nerve transection injury or surgical intervention.

Fabrication of a 3D Printed PCL Nerve Guide: In Vitro and In Vivo Testing.

Nerve guides are medical devices designed to guide proximal and distal ends of injured peripheral nerves in order to assist regeneration of the damaged nerves. A 3D-printed polycaprolactone (PCL) nerve guide using an aligned gelatin-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) electrospun mat, seeded with PC12 and Schwann cells (SCs) is produced. During characterization with microCT and SEM porosity (55%), pore sizes (675± 40µm), and fiber diameters (382± 25µm) are determined. Electrospun fibers have degree of alignment of 7°, indicating high potential for guidance. On Day 14, PC12 cells migrated from proximal to distal end of nerve guide when SCs are seeded on the guide. After 28 days, over 95% of PC12 are alive and aligned. PC12 cells express early differentiation marker beta-tubulin 10 times more than late marker NeuN. In a 10mm rat sciatic nerve injury, functional recovery evaluated by using static sciatic index (SSI) is observed in mat-free guides and guides containing mat and SCs. Nerve conduction velocities are also improved in these groups. Histological stainings showed tissue growth around nerve guides with highest new tissue organization being observed with mat and cell-free guides. These suggest 3D-printed PCL nerve guides have significant potential for treatment of peripheral nerve injuries.

Reverse engineering of an anatomically equivalent nerve conduit.

Reconstruction of peripheral nervous tissue remains challenging in critical-sized defects due to the lack of Büngner bands from the proximal to the distal nerve ends. Conventional nerve guides fail to bridge the large-sized defect owing to the formation of a thin fibrin cable. Hence, in the present study, an attempt was made to reverse engineer the intricate epi-, peri- and endo-neurial tissues using Fused Deposition Modeling based 3D printing. Bovine serum albumin protein nanoflowers (NF) exhibiting Viburnum opulus 'Roseum' morphology were ingrained into 3D printed constructs without affecting its secondary structure to enhance the axonal guidance from proximal to distal ends of denuded nerve ends. Scanning electron micrographs confirmed the uniform distribution of protein NF in 3D printed constructs. The PC-12 cells cultured on protein ingrained 3D printed scaffolds demonstrated cytocompatibility, improved cell adhesion and extended neuronal projections with significantly higher intensities of NF-200 and tubulin expressions. Further suture-free fixation designed in the current 3D printed construct aids facile implantation of printed conduits to the transected nerve ends. Hence the protein ingrained 3D printed construct would be a promising substitute to treat longer peripheral nerve defects as its structural equivalence of endo- and perineurial organization along with the ingrained protein NF promote the neuronal extension towards the distal ends by minimizing axonal dispersion.

Long Acellular Nerve Allografts Cap Transected Nerve to Arrest Axon Regeneration and Alter Upstream Gene Expression in a Rat Neuroma Model.

Treatments to manage painful neuroma are needed. An operative strategy that isolates and controls chaotic axonal growth could prevent neuroma. Using long acellular nerve allograft to "cap" damaged nerve could control axonal regeneration and, in turn, regulate upstream gene expression patterns. Rat sciatic nerve was transected, and the distal nerve end was reversed and ligated to generate a model end-neuroma. Three groups were used to assess their effects immediately following this nerve injury: no treatment (control), traction neurectomy, or 5-cm acellular nerve allograft cap attached to the proximal nerve. Regeneration of axons from the injured nerve was assessed over 5 months and paired with concurrent measurements of gene expression from upstream affected dorsal root ganglia. Both control and traction neurectomy groups demonstrated uncontrolled axon regeneration revealed using Thy1-GFP rat axon imaging and histomorphometric measures of regenerated axons within the most terminal region of regenerated tissue. The acellular nerve allograft group arrested axons within the acellular nerve allograft, where no axons reached the most terminal region even after 5 months. At 5 months, gene expression associated with regeneration and pain sensitization, including Bdnf, cfos, and Gal, was decreased within dorsal root ganglia obtained from the acellular nerve allograft group compared to control or traction neurectomy group dorsal root ganglia. Long acellular nerve allografts to cap a severed nerve arrested axon regeneration within the acellular nerve allograft. This growth arrest corresponded with changes in regenerative and pain-related genes upstream. Acellular nerve allografts may be useful for surgical intervention of neuroma.

Disrupted Trigeminal Ganglion Development in a Mouse Model of Familial Dysautonomia

Neurons in the trigeminal ganglion (TG) relay somatosensory information from the face and oral cavity to the central nervous system. Arising from the differentiation of both neural crest cell and ectodermal placode cell precursors during embryogenesis, neurons in the TG ultimately encode one sensory modality (i.e., touch, pain, temperature). TG neuron identity is discernable by particular molecular markers, including the mutually exclusive expression of the neurotrophin receptors TrkA, TrkB, or TrkC, which are required for long-term neuronal function and survival. While little is known about the mechanisms that establish and maintain distinct neuronal subpopulations in the TG, disease studies offer some insight. Familial Dysautonomia (FD) is a hereditary neuropathy caused by a mutation in Elongator complex protein 1 (ELP1), which leads to reduced ELP1 protein levels in sensory and autonomic neurons. FD patients have clinical deficits that point to abnormal TG function, including impaired sensation of facial pain and temperature. Moreover, FD patients have smaller trigeminal nerves compared to healthy controls, in the absence of overt degeneration. Given these findings, we hypothesize that ELP1 is necessary for the development and survival of TG sensory neurons. Our initial results uncovered cytoplasmic Elp1 expression in both placode cell- and neural crest cell-derived neurons of the developing mouse TG starting from embryonic day (E)10.5. Using a conditional knockout mouse model in which Elp1 is deleted from Wnt1-positive neural crest cells and derivatives, including sensory neurons, we next examined the effect of Elp1 loss on TG development. Our preliminary data reveal Elp1 depletion from neural crest cells leads to abnormal TG morphology and fewer trigeminal nerve branches as early as embryonic day (E)11, a phenotype that persists throughout development and suggests defects in both neural crest- and placode cell-derived neurons in the TG. TrkA-expressing neurons, which typically function in pain perception, are especially vulnerable to Elp1 loss during this period of TG formation. By E12.5, we observe decreased TrkA expression in distal trigeminal nerve endings and fewer TrkA-positive neuron cell bodies in the TG. Analyses from TUNEL staining reveal increased cell death in the TG at E12.5, suggesting TrkA-expressing neurons, progenitor cells, and/or supporting cells may undergo aberrant apoptosis in Elp1 conditional knockout TG. Together, our results confirm a role for Elp1 in the development and survival of TG sensory neurons. These findings help explain the loss of facial sensation in FD and may guide future therapeutic interventions to increase quality of life for FD patients.

The ataxic neuropathies.

Ataxia is a frequent symptom in neurological cases with many causes. Sensory ataxia (due to involvement of the proprioceptive pathways) is observed in conditions affecting the central nervous system (spinal cord disorder) and the peripheral nervous system (peripheral neuropathy). The latter correspond to what we refer to as 'ataxic neuropathies'. Ataxic neuropathies represent a wide and heterogeneous spectrum of disorders that may affect dorsal root nerves, dorsal root ganglia, nerve trunks, distal nerve endings or all of them together. The identification of a predominant sensory ataxia in a case of peripheral neuropathy should raise the possibility of some specific etiologies. We propose here to present the main causes of ataxic neuropathies, which are identified with diagnostic workflows that are dictated by the topography of the likely sites of lesions in the proprioceptive pathway together with the timing of their occurrence (acute, subacute, or chronic).

Treatment of Neuroma-induced Chronic Pain and Management of Nerve Defects with Processed Nerve Allografts.

Background:Symptomatic neuromas can cause significant chronic pain and negatively impact quality of life. Symptoms often persist despite narcotics and nonoperative interventions, which are largely ineffective. With the opioid crisis, treatments for chronic pain that limit narcotics are needed. Traditional surgical options may result in neuroma recurrence. Autograft reconstruction often results in donor-site morbidity. Processed nerve allografts facilitate axonal growth, nerve regeneration, and eliminate donor-site morbidity.Methods:A literature review was performed to identify studies in which chronic neuroma pain was treated with excision and processed nerve allograft reconstruction. PubMed was queried, and data from the studies were grouped into treatment effective and ineffective groups. Statistical analyses were performed on these groups, and further subgroup analysis was performed on overall change of preoperative and postoperative pain scores using a paired t test.Results:Seven studies fulfilled inclusion criteria yielding 42 patients. Greater than 90% of patients had improvement of pain postoperatively. The preoperative and postoperative pain scores could be determined for 40 patients. The mean preoperative score was 7.9, and the mean postoperative score was 3.54. These results were statistically significant using a paired t test with a P value of <0.001.Conclusions:Chronic pain resulting from symptomatic neuromas can be treated with neuroma excision and nerve stump reconstruction with processed nerve allograft. This obviates autograft-associated donor-site morbidity and provides a platform to potentially restore sensation to the involved nerve whenever a distal nerve end is available. Addressing the root cause is an important paradigm shift for treating symptomatic neuromas.

Investigation of axonal regeneration of Triturus ivanbureschi by using physiological and proteomic strategies

Peripheral nerve injuries are frequently observed and successful treatment depends mainly on the injury type, location of the damage, and the elapsed time prior to treatment. The regenerative capacity is limited only to the embryonic period in many mammalian tissues, but urodele amphibians do not lose this feature during adulthood. The main purpose of this study is to define the recovery period after serious sciatic nerve damage of a urodele amphibian, Triturus ivanbureschi. Experimental transection damage was performed on the sciatic nerves of T. ivanbureschi specimens. The recovery period of sciatic nerves were investigated by walking track analysis, electrophysiological recordings, and bottom-up proteomic strategies at different time points during a 35-day period. A total of 34 proteins were identified related to the nerve regeneration process. This study showed that the expression levels of certain proteins differ between distal and proximal nerve endings during the regeneration period. In distal nerve stumps, transport proteins, growth factors, signal, and regulatory molecules are highly expressed, whereas in proximal nerve stumps, neurite elongation proteins, and cytoskeletal proteins are highly expressed.

(215) Differential Expression of Axonal Transport Related Genes and Pathways in Paclitaxel-Induced Peripheral Neuropathy in Breast Cancer Survivors

Taxol is a common chemotherapy (CTX) drug that is associated with the development of neuropathy. Paclitaxel-induced peripheral neuropathy (PIPN) is the dose limiting toxicity of this CTX drug. Paclitaxel exerts its therapeutic effect by binding to β-tubulin, which interferes with microtubule dynamics and results in microtubule stabilization, mitotic arrest, and apoptosis of cancer cells. However, microtubules are critical for axonal function and for the transport of essential organelles to distal nerve endings. Disruption of axonal transport (AT) can lead to axonal degeneration and neuropathy. The purpose of this pilot study was to evaluate for differential expression (DE) and perturbations in AT related genes and pathways between breast cancer (BC) survivors who did (n=25) and did not (n=25) develop PIPN. Gene expression in peripheral blood was assayed using RNA-seq. BC survivors with PIPN were significantly older; more likely to be unemployed; reported lower alcohol use; had a higher BMI and a poorer functional status; and had a higher number of lower extremity sites with loss of light touch, cold, and pain sensations, and higher vibration thresholds. No between group differences were found in the cumulative dose of paclitaxel received or in the percentage of patients who had a dose reduction or delay due to PIPN. Three candidate paclitaxel metabolizing genes were DE (i.e., TUBB4B, TUBB2A, RFX2) and two pathways associated with AT were significantly perturbed (i.e., axon guidance, regulation of actin cytoskeleton). This study is the first to provide molecular evidence that a number of axonal transport mechanisms identified in preclinical models of various types of neuropathic pain including chemotherapy-induced peripheral neuropathy are found in breast cancer survivors with persistent PIPN and suggest genes for validation and as potential therapeutic targets.

A Mechanistic Understanding of Axon Degeneration in Chemotherapy-Induced Peripheral Neuropathy.

Chemotherapeutic agents cause many short and long term toxic side effects to peripheral nervous system (PNS) that drastically alter quality of life. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and enduring disorder caused by several anti-neoplastic agents. CIPN typically presents with neuropathic pain, numbness of distal extremities, and/or oversensitivity to thermal or mechanical stimuli. This adverse side effect often requires a reduction in chemotherapy dosage or even discontinuation of treatment. Currently there are no effective treatment options for CIPN. While the underlying mechanisms for CIPN are not understood, current data identify a “dying back” axon degeneration of distal nerve endings as the major pathology in this disorder. Therefore, mechanistic understanding of axon degeneration will provide insights into the pathway and molecular players responsible for CIPN. Here, we review recent findings that expand our understanding of the pathogenesis of CIPN and discuss pathways that may be shared with the axonal degeneration that occurs during developmental axon pruning and during injury-induced Wallerian degeneration. These mechanistic insights provide new avenues for development of therapies to prevent or treat CIPN.

Assessment of Functional Outcomes of Distal Nerve Transfers in Brachial Plexus and Peripheral Nerve Injuries Using Histomorphometric Parameters As Prognostic Indicators

Introduction In brachial plexus and peripheral nerve injuries, distal nerve transfers provide an early return of function with minimal donor nerve-related morbidity. In the present study, various histomorphometric parameters have been evaluated to prognosticate the surgical outcomes of distal nerve transfers. Materials and Methods Thirty patients with brachial plexus and peripheral nerve injuries were treated by distal nerve transfers. Prior to the nerve transfer approximately 0.5 cm segment from the distal end of donor nerve and proximal end of recipient nerve were sectioned and evaluated for histomorphometry. Relevant histopathological parameters were used to predict the functional outcomes. Results Donor nerve specimens showing good axonal counts had better functional gains. A lack of fibrosis in the suprascapular and spinal accessory nerves resulted in better shoulder functions with majority of patients having upper brachial plexus injury restoring more than 150 degree of active shoulder abduction and abduction strength of at least M4, which was in contrast to patients displaying fibrosis. Inflammation was present in the donor and recipient nerves in majority of cases, though its correlation with functional gains was not as significant as the number of axons and amount of fibrosis. Presence of demyelination and vasculitis had little bearing in the ultimate functional outcomes. Conclusions This study revealed that the histomorphometric factors have an important role in predicting the functional outcomes in nerve transfers. An understanding of the histomorphometric status of the donor and recipient nerves can form a basis for early prediction of functional outcomes.

Contralateral C7 Transfer via Both Vascularized Ulnar Nerve and Medial Antebrachial Cutaneous Nerve With the Ulnar Artery Anastomosed to the Arteria transversa Colli to Repair Brachial Plexus Avulsion

Background: Contralateral C7 nerve transfer to the median nerve has been used in an attempt to restore finger flexion in patients with total brachial plexus avulsion injury. However, the results have not been satisfactory mainly because of the requirement to use a long bridging nerve graft, which causes an extended nerve regeneration process and irreversible muscle atrophy. A new procedure involving contralateral C7 nerve transfer via both vascularized ulnar nerve and medial antebrachial cutaneous nerve with the ulnar artery anastomosed to the arteria transversa colli is presented here. Methods: It was performed in 25 patients with total brachial plexus avulsion injury. Contralateral C7 nerve root was coapted to the distal end of the ipsilateral vascularized ulnar nerve and medial antebrachial cutaneous nerve with the ulnar artery is anastomosed to the arteria transversa colli. The ulnar nerve was secured to the median nerve, and medial antebrachial cutaneous nerve was used to repair musculocutaneous nerve. Electromyography and ultrasonography were used to evaluate the early recovery. Recovery of finger, wrist, and elbow flexion was evaluated with the use of the modified British Medical Research Council muscle grading system. Results: Electromyography showed the early recovery by 3 months postoperatively, and smooth blood flow at the anastomotic stoma can be seen through ultrasound. The mean follow-up period (and standard deviation) was 20 ± 6 months. Motor function with a grade of M3+ or greater was attained in 60% of the patients for elbow flexion, 64% of the patients for finger flexion, 53% of the patients for thumb flexion, and 72% of the patients for wrist flexion. Conclusions: Contralateral C7 nerve transfer via both vascularized ulnar nerve and medial antebrachial cutaneous nerve with the ulnar artery anastomosed to the arteria transversa colli speeds up the nerve regeneration in patients with total brachial plexus avulsion injury and improve the utilization of contralateral C7 fiber. There was satisfactory recovery of finger flexion and wrist flexion in this series.

The microenvironment and cell behavior

Event Abstract Back to Event The microenvironment and cell behavior Vasif Hasirci1 1 Middle East Technical University, Biological Sciences, Türkiye Extracellular matrix and its organization are very critical for the function and viability of the tissues. Tissues are organized in a variety of complex forms and the current approach in design for biomaterials and tissue engineering takes this into account in order to understand the cell and material interactions and also to produce successful products. The nerves are organized in the form of fiber bundles and most of the current treatments of severed peripheral and central nervous system elements aim to provide a form of guiding element[1]. This could be a simple empty tube into which severed proximal and the distal nerve ends are introduced in order to support aligning and healing (Fig 1A). Another tissue consisting of highly aligned elements is the muscle[2]. An example of repair attempt to damaged muscle tissue after a heart attack is to employ a muscle patch with stem cells aligned on electrospun polymeric fibers prepared in the form of a mesh, a mat or a bundle (Fig 1B). When a systematic attempt is made to determine the factors that make a surface attractive or repulsive for cells, planned creation of surfaces highly decorated with topographical and chemical/biological features using micro- and nanotechnology methods. Topographical features such as micro and nano-sized posts/pillars and wells are designed for increasing attachment on the surface and also for forcing conformational changes in the cell and in their nuclei. Physical patterns might convince cells to adhere preferentially on certain regions or constrain them in voids or gaps much smaller than their normal sizes (Figs 1C , 1D)[3],[4]. There are also chemical and biological patterning approaches that are used to create adhesive and repulsive regions or islands and posts with tips modified with cell adhesive molecules such as fibronectin or cell repulsive molecules such as PEG. The results of these intense activities find application in other fields such as biosensors. Thus the design of the microenvironment of the cells is becoming a very important area in the field of biomaterials and tissue engineering and the newly evolving techniques contribute significantly to the advances made in these fields. Figure 1. Various extracellular surfaces designed and used in guidance of various tissues. A) Nerve guide[1], B) Cardiac patch[2], C) Selective attachment of cells on micropillared surfaces[3], D) Micropatterned surface with cells arranging their cytoskeleton to fit the pillar dimensions for bone tissue studies[4]. BIOMATEN for the Ministry of Development funds; METU Grants

Contralateral Hyperalgesia from Injection of Endothelin-1 into the Ipsilateral Paw Requires Efferent Conduction into the Contralateral Paw.

Contralateral hyperalgesia, occurring after unilateral injury, is usually explained by central sensitization in spinal cord and brain. We previously reported that injection of endothelin-1 (ET-1) into one rat hindpaw induces prolonged mechanical and chemical sensitization of the contralateral hindpaw. Here, we examined the role of contralateral efferent activity in this process. ET-1 (2 nmol, 10 μL) was injected subcutaneously into the plantar surface of right (ipsilateral) hindpaw (ILP), and the thermal response latency and mechanical threshold for nocifensive withdrawal were determined by the use of, respectively, plantar radiant heating and von Frey filaments, for both ILP and contralateral hindpaws (CLP). Either paw was anesthetized for 60 minutes by direct injection of bupivacaine (0.25%, 40 μL), 30 minutes before ET-1. Alternatively, the contralateral sciatic nerve was blocked for 6 to 12 hours by percutaneous injection of bupivacaine-releasing microspheres 30 minutes before injection of ET-1. Systemic actions of these bupivacaine formulations were simulated by subcutaneous injection at the nuchal midline. After the injection of ET-1, the mechanical threshold of both ILP and CLP decreased by 2 hours, appeared to be lowest around 24 hours, and recovered through 48 hours to preinjection baseline at 72 hours. These hypersensitive responses were suppressed by bupivacaine injected into the ipsilateral paw before ET-1. Injection of the CLP by bupivacaine also suppressed the hypersensitivity of the CLP at all test times, and that of the ILP, except at 2 hours when it increased the sensitivity. This same pattern of change occurred when the contralateral sciatic nerve was blocked by bupivacaine-releasing microspheres. The systemic actions of these bupivacaine formulations were much smaller and only reached significance at 24 hours post-ET-1. Thermal hypersensitivity after ET-1 injection also occurred in both ILP and CLP and showed the same pattern in response to the 2 contralateral anesthetic procedures. These results show that efferent transmission through the contralateral innervation into the paw is necessary for contralateral sensitization by ET-1, suggesting that the release of substances by distal nerve endings is involved. The release of substances in the periphery is essential for contralateral sensitization by ET-1 and may also contribute to secondary hyperalgesia, occurring at loci distant from the primary injury, that occurs after surgery or nerve damage.

Improved neurological outcome by intramuscular injection of human amniotic fluid derived stem cells in a muscle denervation model.

PurposeThe skeletal muscle develops various degrees of atrophy and metabolic dysfunction following nerve injury. Neurotrophic factors are essential for muscle regeneration. Human amniotic fluid derived stem cells (AFS) have the potential to secrete various neurotrophic factors necessary for nerve regeneration. In the present study, we assess the outcome of neurological function by intramuscular injection of AFS in a muscle denervation and nerve anastomosis model.Materials and MethodsSeventy two Sprague-Dawley rats weighing 200–250 gm were enrolled in this study. Muscle denervation model was conducted by transverse resection of a sciatic nerve with the proximal end sutured into the gluteal muscle. The nerve anastomosis model was performed by transverse resection of the sciatic nerve followed by four stitches reconnection. These animals were allocated to three groups: control, electrical muscle stimulation, and AFS groups.ResultsNT-3 (Neurotrophin 3), BDNF (Brain derived neurotrophic factor), CNTF (Ciliary neurotrophic factor), and GDNF (Glia cell line derived neurotrophic factor) were highly expressed in AFS cells and supernatant of culture medium. Intra-muscular injection of AFS exerted significant expression of several neurotrophic factors over the distal end of nerve and denervated muscle. AFS caused high expression of Bcl-2 in denervated muscle with a reciprocal decrease of Bad and Bax. AFS preserved the muscle morphology with high expression of desmin and acetylcholine receptors. Up to two months, AFS produced significant improvement in electrophysiological study and neurological functions such as SFI (sciatic nerve function index) and Catwalk gait analysis. There was also significant preservation of the number of anterior horn cells and increased nerve myelination as well as muscle morphology.ConclusionIntramuscular injection of AFS can protect muscle apoptosis and likely does so through the secretion of various neurotrophic factors. This protection furthermore improves the nerve regeneration in a long term nerve anastomosis model.

Comparison of three methods on bilateral proper digital nerve injuries for repairing severed fingers

Objective To compare the clinical efficacy of the nerve bow （digital nerve and cutaneous antebrachii later-als） with end-to-side neuroanastomosis and traditional end-to-end neuroanastomosis for repairing bilateral proper digital nerve inju-ries while replanting injured fingers. Methods A total of 57 patients with bilateral proper digital nerve injuries from March 2009 to September 2012 were retrospectively analyzed. The patients were divided into three groups according to different treatments：19 patients underwent nerve graft bow end-to-side neuroanastomosis. During operation, a cutaneous antebrachii laterals nerve was freed and obtained from the homolateral forearm, which were sutured with bilateral distal digital nerve end to end, then nerve bow was formed. The bilateral proximal ends of digital nerve were sutured end-to-side bow, respectively. 22 patients underwent digital nerve bow end-to-side neuroanastomosis. During operation, bilateral distal ends and proximal ends were sutured respectively;con-sequently, the distal and proximal nerve bows were formed. A cutaneous antebrachii laterals nerve was obtained from the homolat-eral forearm, then divided equally to 2 parts which were used to bridge the 2 nerve digital nerve bow end-to-side neuroanastomosis bows. 16 patients underwent nerve graft with end-to-end neuroanastomosis. The sensation of finger plup, two point discrimination and motion of joints were evaluated. Results All patients achieved primary healing of wound after operation, with 57 fingers re-covered uneventfully. In nerve graft bow end-to-side neuroanastomosis group, 18 patients were followed up for 3-15 months;the average result of sensation measurement was S3＋;the average result of two point discrimination was 5.1±0.8 mm. In digital nerve bow end-to-side neuroanastomosis group, 19 patients were followed up for 4-15 months;the average result of sensation measure-ment was S3; the average result of two point discrimination was 6.3 ± 0.9 mm. In nerve graft with end-to-end neuroanastomosis group, 12 patients were followed up for 3-14 months;the average result of sensation measurement was S2, the average result of two point discrimination was 7.2±1.4 mm. According to total active motion scales, there had no difference in results of motion of joints in the 3 groups. Conclusion The nerve bow end-to-side neuroanastomosis is valuable method for repairing bilateral proper digi-tal nerve injuries at the same time, which can restore sensation of fingers. Key words: Anastomosis; Surgical Fingers Reconstructive surgical procedures Trauma; nervous system