Human Nerve Research Articles

Application of Human Epineural Conduit Supported with Human Mesenchymal Stem Cells as a Novel Therapy for Enhancement of Nerve Gap Regeneration

Various therapeutic methods have been suggested to enhance nerve regeneration. In this study, we propose a novel approach for enhancement of nerve gap regeneration by applying human epineural conduit (hEC) supported with human mesenchymal stem cells (hMSC), as an alternative to autograft repair. Restoration of 20 mm sciatic nerve defect with hEC created from human sciatic nerve supported with hMSC was tested in 4 experimental groups (n = 6 each) in the athymic nude rat model (Crl:NIH-Foxn1rnu): 1 - No repair control, 2 - Autograft control, 3 - Matched diameter hEC filled with 1 mL saline, 4 - Matched diameter hEC supported with 3 × 106 hMSC. Assessments included: functional tests: toe-spread and pinprick, regeneration assessment by immunofluorescence staining: HLA-1, HLA-DR, NGF, GFAP, Laminin B, S-100, VEGF, vWF and PKH26 labeling; histomorphometric analysis of myelin thickness, axonal density, fiber diameter and myelinated nerve fibers percentage; Gastrocnemius Muscle Index (GMI) and muscle fiber area ratio. Best sensory and motor function recovery, as well as GMI and muscle fiber area ratio, were observed in the autograft group, and were comparable to the hEC with hMSC group (p = 0.038). Significant improvements of myelin thickness (p = 0.003), fiber diameter (p = 0.0296), and percentage of myelinated fibers (p < 0.0001) were detected in hEC group supported with hMSC compared to hEC with saline controls. At 12-weeks after nerve gap repair, hEC combined with hMSC revealed increased expression of neurotrophic and proangiogenic factors, which corresponded with improvement of function comparable with the autograft control. Application of our novel hEC supported with hMSC provides a potential alternative to the autograft nerve repair.Graphical

Phase 1b Randomized Controlled Study of Short Course Topical Recombinant Human Nerve Growth Factor (rhNGF) for Neuroenhancement in Glaucoma: Safety, Tolerability, and Efficacy Measure Outcomes

No approved therapies directly target retinal ganglion cells (RGCs) for neuroprotection or neuroenhancement in glaucoma. Recombinant human nerve growth factor (rhNGF) has been shown to promote RGC survival and function in animal models of optic neuropathy. Here we evaluate the safety, tolerability, and efficacy of short-term, high-dose rhNGF eye drops versus placebo in a cohort of glaucoma patients. This was a prospective, phase 1b, single-center, randomized, double-masked, vehicle-controlled, parallel-group study. This study was designed to assess safety and tolerability as well as short-term neuroenhancement of structure and function (clinicaltrials.gov NCT02855450). A total of 60 open-angle glaucoma patients were randomized 40:20 to receive either 180 μg/mL rhNGF or vehicle control eye drops in both eyes, 3 times daily for 8 weeks, with a 24-week post-treatment follow-up. One eye was officially selected as the study eye, although both eyes were studied and dosed. Primary endpoints were safety, as assessed by adverse events, and tolerability, as assessed by patient-reported outcomes. Secondary outcome measures included best corrected visual acuity (BCVA), Humphrey visual field, electroretinograpy (ERG), and optical coherence tomography (OCT) of retinal nerve fiber layer (RNFL) thickness at baseline, after 8 weeks of treatment, and at 4 and 24 weeks after treatment (12 and 32 weeks total). Of the 60 randomized patients, 23 were female (38%) and the average age was 66.1 years. Through week 32, there were no treatment-related serious adverse events, including no unexpectedly severe progression of optic neuropathy, no adverse events affecting ocular function or pressure, and no drug-related systemic toxicity. Topical high-dose rhNGF was tolerated well, with a low level of symptom burden mainly eliciting periocular ache (in 52% of treated group and 5% of placebo group) and only 3 patients (7.5%) discontinuing treatment because of discomfort, of whom 1 patient (2.5%) prematurely withdrew from the study. There were no statistically significant differences in global indices of Humphrey visual field and no meaningful differences in total, quadrant, or clock-hour mean RNFL thickness between the groups, although both of these function and structure measures showed nonsignificant trends toward significance in favor of rhNGF. Real-world participant data was used to generate an estimate of cohort size needed to power subsequent studies. Use of rhNGF is safe and tolerable in a topical 180-μg/mL formulation. Although no statistically significant short-term neuroenhancement was detected in this trial, given the strong effects of NGF in preclinical models and the trends detected in this study, analysis for efficacy in a neuroprotection trial is warranted. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Comparative study of decellularization techniques to obtain natural extracellular matrix scaffolds of human peripheral-nerve allografts.

We hypothesize that adding sonication cycles to the process of decellularization of cadaveric human peripheral nerves will increase the removal of cell debris and myelin sheath, increasing their utility as allografts. Our aim of this study was to develop a decellularization protocol that allows the removal of cells and myelin sheath without detrimental effects on nerve architecture. Segments of ulnar and median nerves from human donors, isolated both before and after cardiac arrest, were subjected to two methods of decellularization: two-detergent-based (M1) and the same method with sonication added (M2). We evaluated the histology of unprocessed and decellularized nerves (n = 24 per group) for general morphology, presence of cell nuclei, nuclear remnants, collagen fibers, and myelin. We performed immunohistochemistry to verify the removal of Schwann cells associated with histomorphometry. We used scanning electron microscopy (EM) to evaluate the ultrastructure of both native and decellularized nerves. The efficacy of decellularization was assessed by analysis of genomic DNA. Histology confirmed that both decellularization protocols were adequate and maintained natural nerve architecture. Scanning EM showed that 3D ultrastructural architecture also was maintained. Histomorphometric parameters showed a more complete removal of the myelin with the M2 protocol than with M1 (p = 0.009). Fiber diameter and density were not modified by decellularization methods. Sonication can be a complementary method to decellularization of peripheral nerve allografts with sonication increasing the effectiveness of detergent-based protocols for the removal of unwanted cellular components from peripheral nerve allografts.

Role of NaV 1.7 in action potential conduction along human bronchial vagal afferent C-fibres.

The purpose of this study was to determine the role of NaV 1.7 in action potential conduction in C-fibres in the bronchial branches of the human vagus nerve. Bronchial branches of the vagus nerve were dissected from human donor tissue. The C-wave of the electrically evoked compound action potential was quantified in the absence and presence of increasing concentrations of the selective NaV 1.7 blocking drugs, PF-05089771 and ST-2262, as well as the NaV 1.1, 1.2, and 1.3 blocking drug ICA121-431. The efficacy and potency of these inhibitors were compared to the standard NaV 1 blocker, tetrodotoxin. We then compared the relative potencies of the NaV 1 blockers in inhibiting the C-wave of the compound action potential, with their ability to inhibit parasympathetic cholinergic contraction of human isolated bronchi, a response previously shown to be strictly dependent on NaV 1.7 channels. The selective NaV 1.7 blockers inhibited the C-wave of the compound action potential with potencies similar to that observed in the NaV 1.7 bronchial contractions assay. Using rt-PCR, we noted that NaV 1.7 mRNA was strongly expressed and transported down the vagus nerve bundles. NaV 1.7 blockers can prevent action potential conduction in the majority of vagal C-fibres arising from human bronchi. Blockers of NaV 1.7 channels may therefore have value in inhibiting the responses to excessive airway C-fibre activation in inflammatory airway disease, responses that include coughing as well as reflex bronchoconstriction and secretions.

A Novel Alaska Pollock Gelatin Sealant Shows Higher Bonding Strength and Nerve Regeneration Comparable to That of Fibrin Sealant in a Cadaveric Model and a Rat Model

A novel biocompatible sealant composed of Alaska pollock-derived gelatin (ApGltn) has recently shown good burst strength and biocompatibility in a porcine aorta. The purpose of this study was to investigate the bonding strength and biocompatibility of the ApGltn sealant in transected digital nerves of fresh frozen cadavers and in the sciatic nerves of a rat model. Eighty human digital nerves of fresh frozen cadavers were transected for biomechanical traction testing. They were treated with four surgical interventions: (1) suture plus ApGltn sealant; (2) suture; (3) ApGltn sealant; and (4) fibrin sealant. Forty-three sciatic nerves of male Wistar rats were used for functional and histopathologic evaluation. They were treated with six surgical interventions: (1) suture plus ApGltn sealant; (2) suture; (3) ApGltn sealant; (4) fibrin sealant; (5) resection with a 5-mm gap (10 rats per group); and (6) sham operation (three rats). Macroscopic confirmation, muscle weight measurement, and histopathologic findings including G-ratio were examined 8 weeks after the procedure. The maximum failure load of the ApGltn sealant was significantly higher than that of a fibrin sealant (0.22 ± 0.05 N versus 0.06 ± 0.04 N). The maximum failure load of the ApGltn sealant was significantly lower that of suture plus ApGltn sealant (1.37 N) and suture (1.27 N). Functional evaluation and histologic examination showed that sciatic nerves repaired with ApGltn sealant showed similar nerve recovery compared to repair with the suture and fibrin sealant. The ApGltn sealant showed higher bonding strength and equal effect of nerve regeneration when compared with the fibrin sealant.

Origin, branching pattern, foraminal and intraspinal distribution of the human lumbar sinuvertebral nerves

BACKGROUND CONTEXTThe lumbar sinuvertebral nerve (SVN) innervates the outer posterior intervertebral disc (IVD); it is thought to mediate discogenic low-back pain (LBP). Controversy, however, exists on its origins at higher (L1–L2) versus lower (L3–L5) lumbar levels. Additionally, lack of knowledge regarding its foraminal and intraspinal branching patterns and extensions may lead to iatrogenic damage. PURPOSETo systematically describe the origins of the L2 and L5 SVNs, their morphological variation in the intervertebral foramen (IVF) and intraspinal distribution. STUDY DESIGNDissection-based study of 20 SVNs with histological confirmation in five embalmed human cadavers. METHODSThe origin, branching pattern and distribution of the L2 and L5 SVNs was investigated bilaterally in five human cadavers using dorsal and anterolateral dissection approaches. Parameters studied included somatic and/or autonomic SVN root contributions, foraminal SVN morphology and course, diameter, branching point, intraspinal distribution and IVD innervation pattern. Nerve tissue was confirmed by immunostaining for neurofilament and S100 proteins. RESULTSThe SVN and its origins was identified in all except one IVF at L2 and in all foramina at L5. At L2, the SVN arose in nearly 90% of sides from both somatic and autonomic roots and at L5 in 40% of sides. The remaining SVNs were formed by purely autonomic roots. The SVN arose from significantly more roots at L2 than L5 (3.1 ± 0.3 vs. 1.9 ± 0.3, respectively; p=.022). Four different SVN morphologies could be discerned in the L2 IVF: single filament (22%), multiple (parallel or diverging) filament (33%), immediate splitting (22%) and plexiform (22%) types, whereas the L5 SVN consisted of single (90%) and multiple (10%) filament types. SVN filaments were significantly thicker at L2 than L5 (0.48 ± 0.06 mm vs. 0.33 ± 0.02 mm, respectively; p=.043). Ascending SVN filaments coursed roughly parallel to the exiting spinal nerve root trajectory at L2 and L5. Branching of the SVN into ascending and descending branches occurred mostly intraspinal both at L2 and L5. Spinal canal distribution was also similar for L2 and L5 SVNs. Lumbar posterior IVDs were innervated by the descending branch of the parent SVN and ascending branch of the subjacent SVN. CONCLUSIONSThe SVN at L2 originates from both somatic and autonomic roots in 90% of cases and at L5 in 40% of cases. The remaining SVNs are purely autonomic. In the IVF, the L2 SVN is morphologically heterogeneous, but generally consists of numerous filaments, whereas at L5 90% contains a single SVN filament. The L2 SVN is formed by more roots and is thicker than the L5 SVN. Intraspinal SVN distribution is confined to its level of origin; lumbar posterior IVDs are innervated by corresponding and subjacent SVNs (ie, two spinal levels). CLINICAL SIGNIFICANCEOur findings indicate that L5 discogenic LBP may be mediated both segmentally and nonsegmentally in 40% of cases and nonsegmentally in 60% of cases. Failure of lower lumbar discogenic pain treatment may be the result of only interrupting the nonsegmental pathway, but not the segmental one as well. Relating SVN anatomy to microsurgical spinal approaches may prevent iatrogenic damage to the SVN and the formation of postsurgical back pain.

Live Imaging of Primary Neurons in Long-Term Cryopreserved Human Nerve Tissue.

Tissue cryopreservation provides a convenient solution for tackling one of the major problems in neuroscience research, namely, the scarce availability of human nerve tissues, especially if needed alive. While brain tissue can be used only postmortem, live nerve tissue can reasonably well be harvested from the periphery. A valuable source of primary neurons is the intestine, which compared with brain has the advantage to be safely accessible via endoscopy. The nerve tissue innervating the intestine (the enteric nervous system; ENS) can be sampled with regular endoscopic biopsy forceps and remains viable for multiple physiological and immunohistochemical tests, as previously demonstrated. Here, we present a method to preserve, over longer periods of time, human primary neurons contained in these biopsies. The use of a cryoprotective agent and the application of controlled cooling revealed to be crucial to properly store the nerve tissue and to enable functional measurements after thawing. These primary neurons were evaluated for functionality (live imaging) and morphology (histology) up to one year after cryopreservation. Calcium (Ca2+) imaging indicated that human primary neurons remained viable and responded to selective stimulations (serotonergic and nicotinic agonists) after cryopreservation. Additionally, immunohistochemistry performed with specific neuronal markers showed that nerve structure and neuronal morphology were retained, with no signs of cellular damage. In this study, we demonstrate that the human ENS is a realistic source of primary neurons, which can be successfully preserved over long times and as such can be exploited both for gastrointestinal-specific as well as for general neuroscience research.

Editors' Note: Guillain-Barré Syndrome in the Placebo and Active Arms of a COVID-19 Vaccine Clinical Trial

In “Guillain-Barré Syndrome in the Placebo and Active Arms of a COVID-19 Vaccine Clinical Trial,” Márquez Loza et al. presented a patient who developed the Guillain-Barré syndrome (GBS) after being vaccinated in a COVID-19 vaccine clinical trial and highlighted the fact that this should not be considered a postvaccination complication, given that, by chance alone, 900–2,200 people can be expected to develop GBS within 6 weeks of a 1-dose vaccine and 1,500–3,700 people can be expected to develop GBS within 10 weeks of a 2-dose vaccine. Willer comments that although vaccines can increase the risk of GBS because of antibody production, they can also decrease the risk of GBS because of infection prevention. On behalf of the authors, Amato agrees that vaccines can reduce the risk of postinfection GBS in general but notes that a large epidemiologic cohort study found no causal relationship between COVID-19 and GBS and no evidence of molecular mimicry between any SARS-CoV-2 proteins and axonal or myelin proteins in human nerves. Amato recommends performance of large-scale epidemiologic studies and meta-analyses to better understand the relationship between COVID-19 vaccination and GBS. In “Guillain-Barré Syndrome in the Placebo and Active Arms of a COVID-19 Vaccine Clinical Trial,” Márquez Loza et al. presented a patient who developed the Guillain-Barré syndrome (GBS) after being vaccinated in a COVID-19 vaccine clinical trial and highlighted the fact that this should not be considered a postvaccination complication, given that, by chance alone, 900–2,200 people can be expected to develop GBS within 6 weeks of a 1-dose vaccine and 1,500–3,700 people can be expected to develop GBS within 10 weeks of a 2-dose vaccine. Willer comments that although vaccines can increase the risk of GBS because of antibody production, they can also decrease the risk of GBS because of infection prevention. On behalf of the authors, Amato agrees that vaccines can reduce the risk of postinfection GBS in general but notes that a large epidemiologic cohort study found no causal relationship between COVID-19 and GBS and no evidence of molecular mimicry between any SARS-CoV-2 proteins and axonal or myelin proteins in human nerves. Amato recommends performance of large-scale epidemiologic studies and meta-analyses to better understand the relationship between COVID-19 vaccination and GBS.

Author Response: Guillain-Barré Syndrome in the Placebo and Active Arms of a COVID-19 Vaccine Clinical Trial.

We thank Dr. Willer for his interest in our case report.1 We agree that vaccines can reduce the risk of Guillain-Barré syndrome (GBS) by reducing infection, but this generally assumes that the specific infection that the vaccine targets also increases the risk of GBS.2 However, as mentioned in our article, a large epidemiological-cohort study from Great Britain found no evidence for causality between COVID-19 and GBS.3 A complicating factor is the reduced incidence of GBS during the pandemic that may be attributed to social distancing, wearing masks, and better hygiene. Nonetheless, GBS and COVID-19 incidences vary between regions and do not correlate with one another. These authors also found no evidence of molecular mimicry between any SARS-CoV-2 proteins and human nerve axonal or myelin proteins that might implicate molecular mimicry. Furthermore, not all vaccines cause GBS. Standard epidemiologic methods were used to identify the rare risk of GBS with other vaccines—such as H1N1—and will be needed to ascertain if there is a risk present for the different available COVID-19 vaccinations.

Amyloid-Beta Peptides and Activated Astroglia Impairs Proliferation of Nerve Growth Factor Releasing Cells In Vitro: Implication for Encapsulated Cell Biodelivery-Mediated AD Therapy

Alzheimer’s disease (AD) treatment is constrained due to the inability of peripherally administered therapeutic molecules to cross the blood–brain barrier. Encapsulated cell biodelivery (ECB) devices, a tissue-targeted approach for local drug release, was previously optimized for human mature nerve growth factor (hmNGF) delivery in AD patients but was found to have reduced hmNGF release over time. To understand the reason behind reduced ECB efficacy, we exposed hmNGF-releasing cells (NGC0211) in vitro to human cerebrospinal fluid (CSF) obtained from Subjective Cognitive Impairment (SCI), Lewy Body Dementia (LBD), and AD patients. Subsequently, we exposed NGC0211 cells directly to AD-related factors like amyloid-β peptides (Aβ40/42) or activated astrocyte-conditioned medium (Aβ40/42/IL-1β/TNFα-treated) and evaluated biochemical stress markers, cell death indicators, cell proliferation marker (Ki67), and hmNGF release. We found that all patients’ CSF significantly reduced hmNGF release from NGC0211 cells in vitro. Aβ40/42, inflammatory molecules, and activated astrocytes significantly affected NGC0211 cell proliferation without altering hmNGF release or other parameters important for essential functions of the NGC0211 cells. Long-term constant cell proliferation within the ECB device is critically important to maintain a steady cell population needed for stable mNGF release. These data show hampered proliferation of NGC0211 cells, which may lead to a decline of the NGC0211 cell population in ECBs, thereby reducing hmNGF release. Our study highlights the need for future studies to strengthen ECB-mediated long-term drug delivery approaches.

Electrophysiological Responses in the Human S3 Nerve During Sacral Neuromodulation for Fecal Incontinence.

Intra-operative electrode placement for sacral neuromodulation (SNM) relies on visual observation of motor contractions alone, lacking complete information on neural activation from stimulation. This study aimed to determine whether electrophysiological responses can be recorded directly from the S3 sacral nerve during therapeutic SNM in patients with fecal incontinence, and to characterize such responses in order to better understand the mechanism of action (MOA) and whether stimulation is subject to changes in posture. Eleven patients undergoing SNM were prospectively recruited. A bespoke stimulating and recording system was connected (both intraoperatively and postoperatively) to externalized SNM leads, and electrophysiological responses to monopolar current sweeps on each electrode were recorded and analyzed. The nature and thresholds of muscle contractions (intraoperatively) and patient-reported stimulation perception were recorded. We identified both neural responses (evoked compound action potentials) as well as myoelectric responses (far-field potentials from muscle activation). We identified large myelinated fibers (conduction velocity: 36–60 m/s) in 5/11 patients, correlating with patient-reported stimulation perception, and smaller myelinated fibers (conduction velocity <15 m/s) in 4/11 patients (not associated with any sensation). Myoelectric responses (observed in 7/11 patients) were attributed to pelvic floor and/or anal sphincter contraction. Responses varied with changes in posture. We present the first direct electrophysiological responses recorded from the S3 nerve during ongoing SNM in humans, showing both neural and myoelectric responses. These recordings highlight heterogeneity of neural and myoelectric responses (relevant to understanding MOA of SNM) and confirm that electrode lead position can change with posture.

Median amplitude and frequency analysis of sensory nerve responses to intraepidermal stimulation

BackgroundIn clinical practice, small myelinated sensory fibers conveying pain and other sensations, Aδ-fibers, cannot be examined with available nerve conduction study techniques. New methodEquipment available in clinical neurophysiology laboratories is used to record from human sensory nerves multiple averaged responses to non-painful stimulation of intraepidermal nerves. Ten averaged responses are analyzed in all possible pair combinations with an algorithm applied to a 0.45 ms period of amplitude and frequency (power spectrum). The median of the algorithms is compared to control data to identify potentials generated as response to intraepidermal stimulation. ResultsMedian analysis of the algorithm applied to amplitude and frequency of multiple record pairs identifies potentials with conduction velocities of Aδ-fibers. The analysis of frequency (power spectrum) adds data to the analysis of amplitude. Median analysis of multiple record pairs yields more data than analysis of one pair of alternate averages with the same algorithms. Comparison with existing method(s)At present, analysis of one pair of alternate average records with an algorithm is the only method to identify Aδ-fiber generated potentials. Median analysis of the same algorithm applied to the amplitude of multiple record pairs increases the number of Aδ-fiber generated potentials identified. Neither median analysis of amplitude nor frequency of multiple records pairs has ever been used for conduction studies of nerve fibers, including Aδ-fibers. ConclusionsStimulation, recording and data analysis methods used in this study can be applied in the clinical EMG laboratory to identify the conduction velocities of Aδ-fibers in human sensory nerves.

Analysis of Brain MRI Images Using Improved CornerNet Approach.

The brain tumor is a deadly disease that is caused by the abnormal growth of brain cells, which affects the human blood cells and nerves. Timely and precise detection of brain tumors is an important task to avoid complex and painful treatment procedures, as it can assist doctors in surgical planning. Manual brain tumor detection is a time-consuming activity and highly dependent on the availability of area experts. Therefore, it is a need of the hour to design accurate automated systems for the detection and classification of various types of brain tumors. However, the exact localization and categorization of brain tumors is a challenging job due to extensive variations in their size, position, and structure. To deal with the challenges, we have presented a novel approach, namely, DenseNet-41-based CornerNet framework. The proposed solution comprises three steps. Initially, we develop annotations to locate the exact region of interest. In the second step, a custom CornerNet with DenseNet-41 as a base network is introduced to extract the deep features from the suspected samples. In the last step, the one-stage detector CornerNet is employed to locate and classify several brain tumors. To evaluate the proposed method, we have utilized two databases, namely, the Figshare and Brain MRI datasets, and attained an average accuracy of 98.8% and 98.5%, respectively. Both qualitative and quantitative analysis show that our approach is more proficient and consistent with detecting and classifying various types of brain tumors than other latest techniques.

Modeling Traumatic Brain Injury in Human Cerebral Organoids.

Traumatic brain injury (TBI) is a head injury that disrupts the normal brain structure and function. TBI has been extensively studied using various in vitro and in vivo models. Most of the studies have been done with rodent models, which may respond differently to TBI than human nerve cells. Taking advantage of the recent development of cerebral organoids (COs) derived from human induced pluripotent stem cells (iPSCs), which resemble the architecture of specific human brain regions, here, we adapted the controlled cortical impact (CCI) model to induce TBI in human COs as a novel in vitro platform. To adapt the CCI procedure into COs, we have developed a phantom brain matrix, matching the mechanical characteristics of the brain, altogether with an empty mouse skull as a platform to allow the use of the stereotactic CCI equipment on COs. After the CCI procedure, COs were histologically prepared to evaluate neurons and astrocyte populations using the microtubule-associated protein 2 (MAP2) and the glial fibrillary acidic protein (GFAP). Moreover, a marker of metabolic response, the neuron-specific enolase (NSE), and cellular death using cleaved caspase 3 were also analyzed. Our results show that human COs recapitulate the primary pathological changes of TBI, including metabolic alterations related to neuronal damage, neuronal loss, and astrogliosis. This novel approach using human COs to model TBI in vitro holds great potential and opens new alternatives for understanding brain abnormalities produced by TBI, and for the development and testing of new therapeutic approaches.

GUILLAIN BARRÉ SYNDROME POST SARS-COV-2 INFECTION: A CASE REPORT

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Guillain Barre Syndrome (GBS) is a syndrome usually consisting of paralyzing illness following an infectious process. SARS-COV-2 virus has well documented complications including pneumonia, ARDS, nephropathy, and thrombosis. Neurologic sequelae of GBS, as described in our case are much less common (1). CASE PRESENTATION: An 85-year-old African American male with recent COVID-19 infection, who presented to the emergency department with bilateral lower extremity weakness and bilateral upper extremity tingling for 24 hours. Vital signs were stable on admission. Physical exam revealed quadriparesis and sensory loss, areflexia of L4 and S1 and no saddle anesthesia. MRI brain and cervical spine revealed no signs of myelitis. Due to concern for COVID-19 post viral syndrome in the setting of new, rapidly progressing neurological symptoms, IVIG therapy was initiated. An EMG study was performed and was consistent with length dependent sensory and motor polyneuropathy, with mixed demyelinating and axonal features. Furthermore, there was minimal to absent recruitment of most muscles, consistent with high severity of disease. Patient's condition continued to worsen. He was intubated and placed on mechanical ventilatory support. While on mechanical ventilation, plasma exchange (PLEX) was initiated with subsequent improvement of his symptoms. Eventually, he was transferred to acute inpatient rehab to continue recovery. DISCUSSION: The most common peripheral nervous system manifestations of COVID-19 usually involve anosmia and chemosensory dysfunction (2). Case reports have shown an association between COVID-19 and GBS. It remains unclear whether humoral molecular mimicry, as seen in C. Jejuni, is also the driving mechanism behind the pathogenesis of GBS in SARS-CoV-2 (3). Reports have highlighted that no known SARS-CoV-2 epitopes have been found to be homologically similar to human peripheral nerve tissue and therefore unable to support immune driven, previously widely described molecular mechanisms of GBS (4). However, this lack of clear genetic similarity does not exclude immune mediated response as it's possible that immunogenic proteins could be modified post-translationally or have non-linear antibody epitopes driving such response (5). In addition, although there has been no evidence of SARS-CoV-2 detection in CSF (6), a small sample size of CSF studies from COVID 19 patients likely points towards overall inflammation caused by virus leading to immune cascade and possible infiltration of immune cells locally leading to CNS injury (7). CONCLUSIONS: Clinicians treating COVID-19 viral syndromes should be aware of the association between COVID-19 and GBS, especially when caring for patients with rapidly progressing neurologic disease. Further work needs to be done to broaden the understanding of pathogenesis of GBS in such cases. REFERENCE #1: Montalvan V, Lee J, Bueso T et al. Neurological manifestations of COVID-19 and other coronavirus infections: A systematic review. Clinical Neurology and Neurosurgery 194. REFERENCE #2: Lechner M, Chandrasekharan D, Jumani K, Liu et al. Anosmia as a presenting symptom of SARS-CoV-2 infection in healthcare workers - A systematic review of the literature, case series, and recommendations for clinical assessment and management. Rhinology. 2020 Aug 1;58(4):394-399. REFERENCE #3: Loshaj-Shala A, Regazzoni L, Daci A, Orioli M, Brezovska K, Panovska AP, et al. Guillain Barre syndrome (GBS): new insights in the molecular mimicry between C. Jejuni and human peripheral nerve (HPN) proteins. J Neuroimmunology 2015;289: 168–76. DISCLOSURES: No relevant relationships by Mateusz Gorecki, source=Web Response no disclosure on file for Dean Kalam;No relevant relationships by Ahamed Khalyfa, source=Web Response

Technical light-field setup for 3D imaging of the human nerve head validated with an eye model

Abstract With the new technology of 3D light field (LF) imaging, fundus photography can be expanded to provide depth information. This increases the diagnostic possibilities and additionally improves image quality by digitally refocusing. To provide depth information in the human optic nerve head such as in glaucoma diagnostics, a mydriatic fundus camera was upgraded with an LF imager. The aim of the study presented here was the validation of the technical setup and resulting depth estimations with an appropriate eye model. The technical setup consisted of a mydriatic fundus camera (FF450, Carl Zeiss Meditec AG, Jena, Germany) and an LF imager (R12, Raytrix GmbH, Kiel, Germany). The field of view was set to 30°. The eye model (24.65 mm total length) consisted of a two-lens optical system and interchangeable fundus models with papilla excavations from 0.2 to 1 mm in steps of 0.2 mm. They were coated with red acrylic lacquer and vessels were drawn with a thin brush. 15 images were taken for each papilla depth illuminated with green light (wavelength 520 nm ± 20 nm). Papilla depth was measured from the papilla ground to the surrounding flat region. All 15 measurements for each papilla depth were averaged and compared to the printed depth. It was possible to perform 3D fundus imaging in an eye model by means of a novel LF-based optical setup. All LF images could be digitally refocused subsequently. Depth estimation in the eye model was successfully performed over a 30° field of view. The measured virtual depth and the printed model papilla depth is linear correlated. The presented LF setup allowed high-quality 3D one-shot imaging and depth estimation of the optic nerve head in an eye model.

Comparative Study on the Deep Learning Algorithms

Abstract: Deep Learning methods have paved the way for elevating the future technology that is capable of changing the world. In modern times, size of data is increasing with the level of application. Deep learning enables the huge dataset to process the highly optimized algorithms with high accuracy as well as within low time. The network architecture of deep learning works similar to human brain nerves. The network accepts the input dataset and convert the data into matrix form that passed through multiple layers in which, each layer upgrade the data to deliver the prediction or classification at the end. Researchers explored the numerous deep learning models that portrayed an inspiration for developers and benefitted in the field of voice recognition, language translation, image categorization, stock market prediction etc. The concern behind the model is to effectively resolve the numerous tasks which need to distributed representation and human intelligence. The highly advanced processors like CPU and GPU has too enhanced the deep learning application through fast matrix calculations and image processing. We will take the sample of wind dataset and used it for comparing the different Deep Neural Network (DNN) artificial algorithm. Keywords: Analysis, comparison, deep learning, training, prediction.

Human Peripheral Nerve-Derived Pluripotent Cells Can Be Stimulated by In Vitro Bone Morphogenetic Protein-2.

We have recently identified a population of cells within the peripheral nerves of adult rodent animals (mice and rats) that can respond to Bone Morphogenetic Protein-2 (BMP-2) exposure or physical injury to rapidly proliferate. More importantly, these cells exhibited embryonic differentiation potentials that could be induced into osteoblastic and endothelial cells in vitro. The current study examined human nerve specimens to compare and characterize the cells after BMP-2 stimulation. Fresh pieces of human nerve tissue were minced and treated with either BMP-2 (750 ng/mL) or a PBS vehicle for 12 h at 37 °C, before being digested in 0.2% collagenase and 0.05% trypsin-EDTA. Isolated cells were cultured in a restrictive stem cell medium. Significantly more cells were obtained from the nerve pieces with the BMP-2 treatment in comparison with the PBS vehicle controls. Cell colonies started to form at Day 3. Expressions of the four transcription factors, namely, Klf4, c-Myc, Sox2, and Oct4, were confirmed at both the transcriptional and translational levels. The cells can be maintained in the stem cell culture medium for at least 6 weeks without changing their morphology. When the cells were transferred to a fibroblast growth medium, dispersed spindle-shaped motile cells were noted and became fibroblast activated protein-α (FAP) positive with immunocytochemistry staining. The data suggest that human peripheral nerve tissue also contains a population of cells that can respond to BMP-2 and express Klf4, Sox2, cMyc, and Oct4—the four transcription factors driving cell pluripotency. These cells are able to differentiate into FAP-positive fibroblasts. In summary, in human peripheral nerves also reside a population of quiescent cells with pluripotency potential that may be the same cells as rodent nerve-derived adult stem (NEDAPS) cells. It is proposed that these cells are possibly at the core of a previously unknown natural mechanism for healing an injury.

The terminal segment of the human phrenic nerve as a novel implantation site for diaphragm pacing electrodes: Anatomical and clinical description

BackgroundDiaphragm pacing allows certain ventilator-dependent patients to achieve weaning from mechanical ventilation. The reference method consists in implanting intrathoracic contact electrodes around the phrenic nerve during video-assisted thoracic surgery, which involves time-consuming phrenic nerve dissection with a risk of nerve damage. Identifying a phrenic segment suitable for dissection-free implantation of electrodes would constitute progress. Study designThis study characterizes a free terminal phrenic segment never fully described before. We conducted a cadaver study (n = 14) and a clinical observational study during thoracic procedures (n = 54). ResultsA free terminal phrenic segment was observed on both sides in 100% of cases, "jumping" from the pericardium to the diaphragm and measuring 60 mm [95% confidence interval; 48–63] and 72.5 mm [65–82] (right left, respectively; p = 0.0038; cadaver study). This segment rolled up on itself at end-expiration and became unravelled and elongated with diaphragm descent (clinical study). Three categories of fat pads were defined (type 1: pericardiophrenic bundle free of surrounding fat; type 2: single fatty fringe leaving the phrenic nerve visible until diaphragmatic entry; type 3: multiple fatty fringes masking the site of penetration of the phrenic nerve) that depended on body mass index (p = 0.001, clinical study). Hematoxylin-eosin and toluidine blue staining (cadaver study) showed that all of the phrenic fibers in the distal, pre-branching part of the terminal segment were contained within a single epineurium containing a variable number of fascicles (right: 1 [95%CI 0.65–4.01]; left 5 [3.37–7.63]; p = 0.03). ConclusionDiaphragm pacing through periphrenic electrodes positioned on the terminal phrenic segment should be tested.

"Off-the-Shelf" Nerve Matrix Preservation.

Background: Decellularized human nerves overcome the limitations of the current treatments for large peripheral nerve injuries. However, the use of decellularized nerves requires an "off-the-shelf" availability for useful and actual clinical application. In this study, we addressed the preservation of the native and decellularized human nerve matrix in an integrative approach for tissue scaffold production. Materials and Methods: For native nerve matrix preservation analysis, we used histological examination and immunofluorescence to examine the structure, biomechanical assays to evaluate the tensile strength and Young's modulus, and analyzed the extracellular matrix (ECM) composition using enzyme-linked immunosorbent assay (ELISA) and biochemical assays for laminin, collagen and sulfated glycosaminoglycans (sGAG). After decellularization, nuclear remnants and DNA content were evaluated using 4',6-diamidino-2-phenylindole (DAPI) staining and the picogreen quantification assay, as well as immunofluorescence or ELISA for cell rests (S100 protein and myelin staining) evaluation. Decellularized cryopreserved scaffolds were assayed for biomechanics, ECM composition, and structural maintenance. Cytotoxicity assays were performed to evaluate the biocompatibility of the nerve matrix extracts after cryopreservation. Results: We compared different strategies for native nerve storage and found that preservation up to 7 days at 4°C in Roswell Park Memorial Institute medium maintained biomechanical properties, such as Young's modulus and tensile strength, along with the structure and ECM composition, regarding laminin, collagen, and sGAG. After a successful decellularization process, that eliminated cell remnants, nerve scaffolds were frozen in an "in house" formulated cryoprotectant, using an automatic controlled rate freezer. Nerve structure, ECM composition, and biomechanical properties were maintained before and after the freezing process in comparison with native nerves. The extracts of the nerve scaffolds after thawing were not cytotoxic and the freezing process sustained good viability in 3T3 cells (graphical abstract). Conclusion: Since our approach facilitates transport, storage, and provide a ready-to-use alternative, it could be used in a clinical application for the treatment of long-gap peripheral nerve injuries in regenerative medicine.