Conditions Of Electrical Stimulation Research Articles

Mutual oligosynaptic inhibition of group Ia afferents between the anterior and posterior parts of the deltoid in humans.

The anterior (DA) and posterior parts of the deltoid (DP) show alternating contraction during shoulder flexion and extension movements. It is expected that an inhibitory spinal reflex between the DA and DP exists. In this study, spinal reflexes between the DA and DP were examined in healthy human subjects using post-stimulus time histogram (PSTH) and electromyogram averaging (EMG-A). Electrical conditioning stimulation was delivered to the axillary nerve branch that innervates the DA (DA nerve) and DP (DP nerve) with the intensity below the motor threshold. In the PSTH study, the stimulation to the DA and DP nerves inhibited (decrease in the firing probability) 31 of 54 DA motor units and 31 of 51 DP motor units. The inhibition was not provoked by cutaneous stimulation. The central synaptic delay of the inhibition between the DA and DP nerves was 1.5 ± 0.5ms and 1.4 ± 0.4ms (mean ± SD) longer than those of the homonymous facilitation of the DA and DP, respectively. In the EMG-A study, conditioning stimulation to the DA and DP nerves inhibited the rectified and averaged EMG of the DP and DA, respectively. The inhibition diminished with tonic vibration stimulation to the DA and DP and recovered 20-30min after vibration removal. These findings suggest that oligo(di or tri)-synaptic inhibition mediated by group Ia afferents between the DA and DP exists in humans.

Reciprocal inhibition of the thigh muscles in humans: A study using transcutaneous spinal cord stimulation.

Evaluating reciprocal inhibition of the thigh muscles is important to investigate the neural circuits of locomotor behaviors. However, measurements of reciprocal inhibition of thigh muscles using spinal reflex, such as H-reflex, have never been systematically established owing to methodological limitations. The present study aimed to clarify the existence of reciprocal inhibition in the thigh muscles using transcutaneous spinal cord stimulation (tSCS). Twenty able-bodied male individuals were enrolled. We evoked spinal reflex from the biceps femoris muscle (BF) by tSCS on the lumber posterior root. We examined whether the tSCS-evoked BF reflex was reciprocally inhibited by the following conditionings: (1) single-pulse electrical stimulation on the femoral nerve innervating the rectus femoris muscle (RF) at various inter-stimulus intervals in the resting condition; (2) voluntary contraction of the RF; and (3) vibration stimulus on the RF. The BF reflex was significantly inhibited when the conditioning electrical stimulation was delivered at 10 and 20 ms prior to tSCS, during voluntary contraction of the RF, and during vibration on the RF. These data suggested a piece of evidence of the existence of reciprocal inhibition from the RF to the BF muscle in humans and highlighted the utility of methods for evaluating reciprocal inhibition of the thigh muscles using tSCS.

Progress of electrical stimulation to promote peripheral nerve regeneration

This study reviews the latest progress on the research of electrical stimulation（ES） in peripheral nerve regeneration, summarizes the parameters in preclinical experiments and discusses the effect on nerve regeneration. A detailed description is given in the study of conditioning electrical stimulation and nerve conduit scaffolding technology combined with ES, which have been hotly researched in recent years.

Silver electroceutical technology to treat sarcopenia

While the world is rapidly transforming into a superaging society, pharmaceutical approaches to treat sarcopenia have hitherto not been successful due to their insufficient efficacy and failure to specifically target skeletal muscle cells (skMCs). Although electrical stimulation (ES) is emerging as an alternative intervention, its efficacy toward treating sarcopenia remains unexplored. In this study, we demonstrate a silver electroceutical technology with the potential to treat sarcopenia. First, we developed a high-throughput ES screening platform that can simultaneously stimulate 15 independent conditions, while utilizing only a small number of human-derived primary aged/young skMCs (hAskMC/hYskMC). The in vitro screening showed that specific ES conditions induced hypertrophy and rejuvenation in hAskMCs, and the optimal ES frequency in hAskMCs was different from that in hYskMCs. When applied to aged mice in vivo, specific ES conditions improved the prevalence and thickness of Type IIA fibers, along with biomechanical attributes, toward a younger skMC phenotype. This study is expected to pave the way toward an electroceutical treatment for sarcopenia with minimal side effects and help realize personalized bioelectronic medicine.

The Effect of Electrical-Stimulation-Induced Emotion on Time Perception: A Time-Reproduction Task.

Duration cognition refers to an individual's cognition for the duration of a given stimulus. Previous studies have explored the effect of emotions on duration perception; however, the results remain controversial. To explore the characteristics of college students' time perception under electrical stimulation, this study used a time-reproduction task and a within-subject design with electrical-stimulation conditions and target duration as independent variables. Additionally, this study used the average temporal reproduction and the reproduction coefficient of variation as dependent variables; the subjective arousal degree, value, and electrical activity under electric stimulation were recorded simultaneously. The results indicated a significant main effect of electrical stimulation. Compared to non-electrical stimulation, the average temporal reproduction of participants under electrical stimulation was significantly shorter. Additionally, the interaction between electrical stimulation and target duration was significant. Furthermore, with the increase in the target duration, the shortening degree of the average temporal reproduction under the electrical stimulation increased significantly. Additionally, the participants' subjective arousal with electrical stimulation was higher than that without an electrical shock, and the valence with electrical stimulation was lower than that without electrical stimulation. These results suggest that the emotions induced by electrical stimulation increase the internal-clock speed, which leads to the relative overestimation of time perception.

Implantable Electroceutical Approach Improves Myelination by Restoring Membrane Integrity in a Mouse Model of Peripheral Demyelinating Neuropathy.

Although many efforts are undertaken to treat peripheral demyelinating neuropathies based on biochemical interventions, unfortunately, there is no approved treatment yet. Furthermore, previous studies have not shown improvement of the myelin membrane at the biomolecular level. Here, an electroceutical treatment is introduced as a biophysical intervention to treat Charcot-Marie-Tooth (CMT) disease-the most prevalent peripheral demyelinating neuropathy worldwide-using a mouse model. The specific electrical stimulation (ES) condition (50mV mm-1 , 20Hz, 1h) for optimal myelination is found via an in vitro ES screening system, and its promyelinating effect is validated with ex vivo dorsal root ganglion model. Biomolecular investigation via time-of-flight secondary ion mass spectrometry shows that ES ameliorates distribution abnormalities of peripheral myelin protein 22 and cholesterol in the myelin membrane, revealing the restoration of myelin membrane integrity. ES intervention in vivo via flexible implantable electrodes shows not only gradual rehabilitation of mouse behavioral phenotypes (balance and endurance), but also restored myelin thickness, compactness, and membrane integrity. This study demonstrates, for the first time, that an electroceutical approach with the optimal ES condition has the potential to treat CMT disease and restore impaired myelin membrane integrity, shifting the paradigm toward practical interventions for peripheral demyelinating neuropathies.

Monosynaptic facilitation of flexor digitorum superficialis motoneurons mediated by Group Ia afferents from the extensor carpi radialis in humans.

Wrist position is known to affect the grip strength. We focused on the spinal reflex arc, which would support the movement, and investigated the effects of low-threshold afferents from the extensor carpi radialis (ECR) on the excitability of the flexor digitorum superficialis (FDS) motoneurons using the post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods. Electrical conditioning stimulation of an intensity below the motor threshold was applied to the radial nerve branch innervating the ECR. In the PSTH study, changes in the firing probability of single motor units after electrical conditioning stimulation were investigated in seven subjects. An early and significant peak (increase in the firing probability: facilitation) was recorded for 36/60 FDS motor units. The remaining 24 motor units did not show any effects. Weak mechanical conditioning stimulation of the ECR muscle belly induced a similar peak. The central latency of the facilitation was equivalent to that of the homonymous monosynaptic facilitation. In the EMG-A study, changes in the rectified and averaged electromyograms of FDS induced by conditioning stimulation were examined in 12 subjects. An early and significant peak (facilitation) was induced by both electrical and mechanical conditioning stimulations. The facilitation decreased after withdrawal of the vibration to the ECR muscle belly. The facilitation was never induced by cutaneous nerve stimulation in the PSTH and EMG-A studies. These findings suggest that Group Ia afferents from the ECR increase the excitability of FDS motoneurons through a monosynaptic path in the spinal cord. These reflex arcs likely facilitate hand grasping movements.

Monosynaptic facilitation of motoneurons innervating intrinsic hand muscles mediated by group Ia afferents from the extensor carpi radialis in humans

The projection pattern of low‐threshold afferents from the extensor carpi radialis (ECR) to motoneurons supplying intrinsic hand muscles was investigated using the post‐stimulus time‐histogram (PSTH) and electromyogram‐averaging (EMG‐A) methods. Electrical conditioning stimulation was applied to the radial nerve branch innervating the ECR. In the PSTH study, changes in the firing probability of single motor units following the stimulation were examined. An early and significant peak (facilitation) was induced in the motoneurons innervating the muscles, but the facilitation was induced infrequently. The central latency of the facilitation was equivalent to that of homonymous facilitation through monosynaptic path in the spinal cord. In the EMG‐A study, changes in the rectified and averaged electromyograms following the conditioning stimulation were examined. An early and significant peak (facilitation) was also induced. The facilitation disappeared after withdrawal of the vibration to the ECR muscle belly. Cutaneous nerve stimulation overlaying ECR never induced such facilitation in the PSTH and EMG‐A studies. These findings suggest that monosynaptic facilitation mediated by group Ia afferents of ECR to the motoneurons supplying intrinsic hand muscles exists in humans, but the connection seems to be weak. This weakness might allow manipulatory movements of the hand.

Recovering the regenerative potential in chronically injured nerves by using conditioning electrical stimulation.

Chronically injured nerves pose a significant clinical challenge despite surgical management. There is no clinically feasible perioperative technique to upregulate a proregenerative environment in a chronic nerve injury. Conditioning electrical stimulation (CES) significantly improves sensorimotor recovery following acute nerve injury to the tibial and common fibular nerves. The authors' objective was to determine if CES could foster a proregenerative environment following chronically injured nerve reconstruction. The tibial nerve of 60 Sprague Dawley rats was cut, and the proximal ends were inserted into the hamstring muscles to prevent spontaneous reinnervation. Eleven weeks postinjury, these chronically injured animals were randomized, and half were treated with CES proximal to the tibial nerve cut site. Three days later, 24 animals were killed to evaluate the effects of CES on the expression of regeneration-associated genes at the cell body (n = 18) and Schwann cell proliferation (n = 6). In the remaining animals, the tibial nerve defect was reconstructed using a 10-mm isograft. Length of nerve regeneration was assessed 3 weeks postgrafting (n = 16), and functional recovery was evaluated weekly between 7 and 19 weeks of regeneration (n = 20). Three weeks after nerve isograft surgery, tibial nerves treated with CES prior to grafting had a significantly longer length of nerve regeneration (p < 0.01). Von Frey analysis identified improved sensory recovery among animals treated with CES (p < 0.01). Motor reinnervation, assessed by kinetics, kinematics, and skilled motor tasks, showed significant recovery (p < 0.05 to p < 0.001). These findings were supported by immunohistochemical quantification of motor endplate reinnervation (p < 0.05). Mechanisms to support the role of CES in reinvigorating the regenerative response were assessed, and it was demonstrated that CES increased the proliferation of Schwann cells in chronically injured nerves (p < 0.05). Furthermore, CES upregulated regeneration-associated gene expression to increase growth-associated protein-43 (GAP-43), phosphorylated cAMP response element binding protein (pCREB) at the neuronal cell bodies, and upregulated glial fibrillary acidic protein expression in the surrounding satellite glial cells (p < 0.05 to p < 0.001). Regeneration following chronic axotomy is impaired due to downregulation of the proregenerative environment generated following nerve injury. CES delivered to a chronically injured nerve influences the cell body and the nerve to re-upregulate an environment that accelerates axon regeneration, resulting in significant improvements in sensory and motor functional recovery. Percutaneous CES may be a preoperative strategy to significantly improve outcomes for patients undergoing delayed nerve reconstruction.

Monosynaptic facilitation mediated by group Ia afferents from deltoid to biceps brachii motoneurons in humans.

Effects of low-threshold afferents from the anterior (DA), middle (DM) and posterior parts of the deltoid (DP) on the excitability of biceps brachii (BB) motoneurons in humans were studied. We evaluated the effects on individual motor units and motoneuron pool using a post-stimulus time-histogram (PSTH) and an electromyogram-averaging (EMG-A) methods, respectively, in 11 healthy human subjects. Electrical conditioning stimulation was delivered to the axillary nerve branch innervating DA (DA nerve), DM (DM nerve) and DP (DP nerve) with the intensity below the motor threshold. In the PSTH study, stimulation to the DA, DM and DP nerves produced a significant peak (facilitation) in 26/40 (65%), 28/47 (59%) and 0/32 (0%) of BB motor units, respectively. Since the central latency of the facilitation from the DA and DM nerves was 0.1 ± 0.3 and 0.1 ± 0.2ms (mean ± S.D.) longer than that of the homonymous monosynaptic Ia facilitation of BB, respectively, the facilitation thus being compatible with monosynaptic path. In the EMG-A study, stimulation to the DA and DM nerves produced a significant peak (facilitation) for the BB motoneuron pool in all the subjects, whereas stimulation to the DP nerve produced no effect on BB. The facilitation diminished by vibration stimulation, and the suppression lasted for 30-40min after removal of the vibration. Therefore, group Ia afferents should be responsible for the facilitation. These findings suggest that monosynaptic facilitation mediated by group Ia afferents from the DA and DM nerves to BB motoneurons exists in humans.

An electroceutical approach enhances myelination via upregulation of lipid biosynthesis in the dorsal root ganglion

As the myelin sheath is crucial for neuronal saltatory conduction, loss of myelin in the peripheral nervous system (PNS) leads to demyelinating neuropathies causing muscular atrophy, numbness, foot deformities and paralysis. Unfortunately, few interventions are available for such neuropathies, because previous pharmaceuticals have shown severe side effects and failed in clinical trials. Therefore, exploring new strategies to enhance PNS myelination is critical to provide solution for such intractable diseases. This study aimed to investigate the effectiveness of electrical stimulation (ES) to enhance myelination in the mouse dorsal root ganglion (DRG)—an ex vivo model of the PNS. Mouse embryonic DRGs were extracted at E13 and seeded onto Matrigel-coated surfaces. After sufficient growth and differentiation, screening was carried out by applying ES in the 1–100 Hz range at the beginning of the myelination process. DRG myelination was evaluated via immunostaining at the intermediate (19 days in vitro (DIV)) and mature (30 DIV) stages. Further biochemical analyses were carried out by utilizing ribonucleic acid sequencing, quantitative polymerase chain reaction and biochemical assays at both intermediate and mature myelination stages. Imaging of DRG myelin lipids was carried out via time-of-flight secondary ion mass spectrometry (ToF-SIMS). With screening ES conditions, optimal condition was identified at 20 Hz, which enhanced the percentage of myelinated neurons and average myelin length not only at intermediate (129% and 61%) but also at mature (72% and 17%) myelination stages. Further biochemical analyses elucidated that ES promoted lipid biosynthesis in the DRG. ToF-SIMS imaging showed higher abundance of the structural lipids, cholesterol and sphingomyelin, in the myelin membrane. Therefore, promotion of lipid biosynthesis and higher abundance of myelin lipids led to ES-mediated myelination enhancement. Given that myelin lipid deficiency is culpable for most demyelinating PNS neuropathies, the results might pave a new way to treat such diseases via electroceuticals.

PPIA and YWHAZ Constitute a Stable Pair of Reference Genes during Electrical Stimulation in Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are multipotent adult stem cells with great potential in regenerative medicine. One method for stimulating proliferation and differentiation of MSCs is via electrical stimulation (ES). A valuable approach for evaluating the response of MSCs to ES is to assess changes in gene expression, relative to one or more reference genes. In a survey of 25 publications that used ES on cells, 70% selected GAPDH as the reference gene. We conducted a study to assess the suitability of six potential reference genes on an immortalized human MSC line following direct current ES at seeding densities of 5000 and 10,000 cells/cm2. We employed three methods to validate the most stable reference genes from qRT-PCR data. Our findings show that GAPDH and ACTB exhibit reduced stability when seeded at 5000 cell/cm2. In contrast, we found that the most stable genes across both plating densities and stimulation regimes were PPIA and YWHAZ. Thus, in ES gene expression studies in MSCs, we support the use of PPIA and YWHAZ as an optimal reference gene pair, and discourage the use of ACTB and GAPDH at lower seeding densities. However, it is strongly recommended that similar verification studies are carried out based on cell type and different ES conditions.

The Number or Type of Stimuli Used for Somatosensory Stimulation Affected the Modulation of Corticospinal Excitability.

Motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) a few milliseconds after this cortical activity following electrical stimulation (ES) result in an inhibition comparable to that by TMS alone; this is called short-latency afferent inhibition (SAI). Cortical activity is observed after mechanical tactile stimulation (MS) and is affected by the number of stimuli by ES. We determined the effects of somatosensory stimulus methods and multiple conditioning stimuli on SAI in 19 participants. In experiment 1, the interstimulus intervals between the conditioning stimulation and TMS were 25, 27 and 29 ms for ES and 28, 30 and 32 ms for MS. In experiment 2, we used 1, 2, 3 and 4 conditioning stimulations of ES and MS. The interstimulus interval between the ES or MS and TMS was 27 or 30 ms, respectively. In experiment 1, MEPs were significantly decreased in both the ES and MS conditions. In experiment 2, MEPs after ES were significantly decreased in all conditions. Conversely, MEPs after MS were significantly decreased after one stimulus and increased after four stimulations, indicating the SAI according to the number of stimuli. Therefore, the somatosensory stimulus methods and multiple conditioning stimuli affected the SAI.

전기 자극을 이용한 CD271 양성 중간엽줄기세포의 연골세포 분화능

Mesenchymal stem cells (MSCs) exhibit self-renewing capacity and multi-lineage differentiation potential. CD271 has been identified as a marker of the most homogeneous MSCs subset. In this study, we separated CD271 positive MSCs (CD271-MSCs) from canine adipose tissue-derived MSCs (AD-MSCs) using immunomagnetic selection method. Both CD271-MSCs and AD-MSCs showed similar morphology and expressed common immunophenotypic markers (CD34, CD44, and CD45). However, CD271-MSCs and AD-MSCs exhibited difference in chondrogenic differentiation potential. Specifically, CD271-MSCs exhibited increased expression levels of chondrocyte specific markers, collagen type II alpha 1 (COL2A1) and Aggrecan compared to AD-MSCs. Also, electrical stimulation (ES)-treated CD271-MSCs have a greater capacity for expressing heat shock protein 70 (HSP70), COL2A1, and Aggrecan compared to control without exogenous differentiation condition. This study might contribute to the differentiation potential of homogenous MSCs into cartilage cells by specific ES condition in the absence of exogenous differentiation agents.

Effects of trunk muscle activation on trunk stability, arm power, blood pressure and performance in wheelchair rugby players with a spinal cord injury

Objective: In wheelchair rugby (WR) athletes with tetraplegia, wheelchair performance may be impaired due to (partial) loss of innervation of upper extremity and trunk muscles, and low blood pressure (BP). The objective was to assess the effects of electrical stimulation (ES)-induced co-contraction of trunk muscles on trunk stability, arm force/power, BP, and WR performance. Design: Cross-sectional study. Setting: Rehabilitation research laboratory and WR court. Participants: Eleven WR athletes with tetraplegia. Interventions: ES was applied to the rectus abdominis, obliquus externus abdominis and erector spinae muscles. For every test, the ES condition was compared to the non-ES condition. Outcome measures: Stability was assessed with reaching tasks, arm force/power with an isokinetic test on a dynamometer, BP during an ES protocol and WR skill performance with the USA Wheelchair Rugby Skill Assessment. Results: Overall reaching distance (ES 14.6 ± 7.5 cm, non-ES 13.4 ± 8.2 cm), and BP showed a significant increase with ES. Arm force (ES 154 ± 106 N, non-ES 148 ± 102 N) and power (ES 37 ± 26 W, non-ES 36 ± 25 W), and WR skills were not significantly improved. Conclusion: ES-induced trunk muscle activation positively affects trunk stability and BP, but not arm force/power. No effects were found in WR skill performance, probably due to abdominal strapping. More research is needed to assess different ES (training) protocols and longitudinal effects.

Is Low-Frequency Electrical Stimulation a Tool for Recovery after a Water Rescue? A Cross-Over Study with Lifeguards.

This study aimed to evaluate the degree to which transcutaneous electrical stimulation (ES) enhanced recovery following a simulated water rescue. Twenty-six lifeguards participated in this study. The rescue consisted of swimming 100 m with fins and rescue-tube: 50 m swim approach and 50 m tow-in a simulated victim. Blood lactate clearance, rated perceived effort (RPE), and muscle contractile properties were evaluated at baseline, after the water rescue, and after ES or passive-recovery control condition (PR) protocol. Tensiomiography, RPE, and blood lactate basal levels indicated equivalence between both groups. There was no change in tensiomiography from pre to post-recovery and no difference between recovery protocols. Overall-RPE, legs-RPE and arms-RPE after ES (mean ± SD; 2.7 ± 1.53, 2.65 ± 1.66, and 2.30 ± 1.84, respectively) were moderately lower than after PR (3.57 ± 2.4, 3.71 ± 2.43, and 3.29 ± 1.79, respectively) (p = 0.016, p = 0.010, p = 0.028, respectively). There was a significantly lower blood lactate level after recovery in ES than in PR (mean ± SD; 4.77 ± 1.86 mmol·L−1 vs. 6.27 ± 3.69 mmol·L−1; p = 0.045). Low-frequency ES immediately after a water rescue is an effective recovery strategy to clear out blood lactate concentration.

Conditioning Electrical Stimulation Accelerates Regeneration in Nerve Transfers.

Compared to the upper limb, lower limb distal nerve transfer (DNT) outcomes are poor, likely due to the longer length of regeneration required. DNT surgery to treat foot drop entails rerouting a tibial nerve branch to the denervated common fibular nerve stump to reinnervate the tibialis anterior muscle for ankle dorsiflexion. Conditioning electrical stimulation (CES) prior to nerve repair surgery accelerates nerve regeneration and promotes sensorimotor recovery. We hypothesize that CES prior to DNT will promote nerve regeneration to restore ankle dorsiflexion. One week following common fibular nerve crush, CES was delivered to the tibial nerve in half the animals, and at 2 weeks, all animals received a DNT. To investigate the effects of CES on nerve regeneration, a series of kinetic, kinematic, skilled locomotion, electrophysiologic, and immunohistochemical outcomes were assessed. The effects of CES on the nerve were investigated. CES-treated animals had significantly accelerated nerve regeneration (p < 0.001), increased walking speed, and improved skilled locomotion. The injured limb had greater vertical peak forces, with improved duty factor, near-complete recovery of braking, propulsive forces, and dorsiflexion (p < 0.01). Reinnervation of the tibialis anterior muscle was confirmed with nerve conduction studies and immunohistochemical analysis of the neuromuscular junction. Immunohistochemistry demonstrated that CES does not induce Wallerian degeneration, nor does it cause macrophage infiltration of the distal tibial nerve. Tibial nerve CES prior to DNT significantly improved functional recovery of the common fibular nerve and its muscle targets without inducing injury to the donor nerve. ANN NEUROL 2020;88:363-374.

Chondrogenic potential of animal adult stem cells through electrical stimulation

Background & Aim Mesenchymal stem cells (MSCs) represent an appealing alternative cell source for cartilage repair. There are studies that induce differentiation into cartilage cells by treating the growth factors in MSCs or altering the properties of MSCs by genetic modification. Electrical stimulation (ES) is known to guide the development and regeneration of many tissues. Use of low-frequency ES for therapeutic purposes has been increasing during the last decades. In this study, we exposed equine adipose tissue-derived MSCs (eAD-MSCs) to ES and assessed changes in the chondrogenic differentiation potential. Methods, Results & Conclusion The cells obtained from equine adipose tissue attached to culture plates and expanded in vitro. Flow cytometric analysis at third passage indicated that the cells were strongly positive for CD44, CD90, and CD105, but negative for CD13, CD34, and CD45. ES was applied to eAD-MSCs cultured under condition of high-density micro-mass under ES of 10 V/cm, with duration of 10 ms and a frequency of 2.0 Hz for three days. We compared chondrogenic differentiation potential of non-ES and ES condition. Expression levels of chondrogenic potential-related markers were examined by quantitative real-time RT-PCR. Articular cartilage is divided into a hyaline cartilage layer and a fibrous cartilage layer. Osteoarthritis (OA) is a disease caused by the natural degeneration of cartilage layer. From the beginning, OA of the middle stage leads to damage of the hyaline cartilage, and damage of the fibrous cartilage at the last stage. We observed the differentiation potential of eAD-MSCs into chondrocytes by specific ES in absence of exogenous growth factors. Gene expression of chondrogenic markers such as type II collagen (COL2A1), Aggrecan, and Sox9 was analyzed at 3 days of ES. Based on the mechanism that chondrocyte formation in articular cavity starts from the aggregation of cells, we observed the differentiation potential of eAD-MSCs into chondrocytes by specific ES in absence of exogenous growth factors. Therefore, this study might contribute to the differentiation of stem cells into cartilage cells by inducing pre-chondrogenic condensation under specific ES.

Noninvasive Electrical Stimulation Improves Photoreceptor Survival and Retinal Function in Mice with Inherited Photoreceptor Degeneration.

PurposeNeurons carry electrical signals and communicate via electrical activities. The therapeutic potential of electrical stimulation (ES) for the nervous system, including the retina, through improvement of cell survival and function has been noted. Here we investigated the neuroprotective and regenerative potential of ES in a mouse model of inherited retinal degeneration.MethodsRhodopsin-deficient (Rho−/−) mice received one or two sessions of transpalpebral ES or sham treatments for 7 consecutive days. Intraperitoneal injection of 5-ethynyl-2′-deoxyuridine was used to label proliferating cells. Weekly electroretinograms were performed to monitor retinal function. Retinal morphology, photoreceptor survival, and regeneration were evaluated in vivo using immunohistochemistry and genetic fate-mapping techniques. Müller cell (MC) cultures were employed to further define the optimal conditions of ES application.ResultsNoninvasive transpalpebral ES in Rho−/− mice improved photoreceptor survival and electroretinography function in vivo. ES also triggered residential retinal progenitor-like cells such as MCs to reenter the cell cycle, possibly producing new photoreceptors, as shown by immunohistochemistry and genetic fate-mapping techniques. ES directly stimulated cell proliferation and the expression of progenitor cell markers in MC cultures, at least partially through bFGF signaling.ConclusionsOur study showed that transpalpebral ES improved photoreceptor survival and retinal function and induced the proliferation, probably photoreceptor regeneration, of MCs; this occurs via stimulation of the bFGF pathways. These results suggest the exciting possibility of applying noninvasive ES as a versatile tool for preventing photoreceptor loss and mobilizing endogenous progenitors for reversing vision loss in patients with photoreceptor degeneration.

Abstract 12: Strategies To Optimize Functional Recovery In Distal Nerve Transfers For Common Fibular Nerve Injuries

Purpose: Footdrop secondary to injury of the common fibular nerve has significant implications on patient function and quality of life. Outcomes following distal nerve transfers (DNT) for restoration of common fibular nerve function are unsatisfactory and often unpredictable. A perioperative technique to improve regeneration and reinnervation of end-targets is therefore of significant clinical interest. We investigated the effects of conditioning electrical stimulation (CES) and daily exercise therapy on regeneration and functional recovery in a rodent model of a DNT. Methods: Sprague Dawley rats were equally divided into a) CES, b) training, c) CES + training, and d) DNT. One week prior to DNT, animals randomized to a CES-cohort received one hour of intermittent electrical stimulation. In keeping with current clinical practice, DNT was performed by identifying the branch of the tibial nerve supplying the lateral gastrocnemius muscle, which was transected and coapted to the distal stump of the denervated common fibular nerve. Post-operatively, animals randomized to a training cohort had one-hour of treadmill training daily for 1 month at 10m/min. Length of axonal extension was quantified after two weeks of regeneration, and motor reinnervation was evaluated weekly by gait analysis of kinetic and kinematic outcomes and skilled locomotion testing. Results: Animals treated with CES prior to DNT had significantly greater regeneration and functional recovery. Two weeks postoperative, the length of axon extension in CES-treated nerves was, significantly longer than in non-conditioned control DNTs (p<0.001). By 8 weeks of regeneration, animals treated with CES+training had significantly higher foot placement scores on the horizontal ladder test (4.3 + 0.3) than DNT-controls (2.6 + 0.2, p<0.001)Animals treated with CES+training had the earliest return of dorsiflexion. By 12 weeks of regeneration, animals treated with CES+training (12.6 ± 2.8o) or with CES (11.2 ± 3.5o), had significantly greater recovery of dorsiflexion when compared to those animals trained only (3.9 ± 2.5o, p<0.001) or DNT controls (no dorsiflexion, p<0.001). Restoration to a more symmetrical gait pattern was significantly improved (p<0.001) among CES+training treated animals; with increased weight bearing (vertical peak forces 0.7 ± 0.03) and increased contact time of the affected limb (duty factor= contralateral - ipsilateral contact time; 0.039 ± 0.007) compared to the other groups (p<0.001). By week 12 of regeneration, CES treated animals exhibited a recovery to symmetry with increased vertical peak forces injured limb (0.65 + 0.02) and reduced differences between limb duty factors (0.046 + 0.05) compared to all other cohorts (p<0.05). Conclusion: Preoperative CES with and without exercise enhances functional recovery with improved dorsiflexion and accelerated restoration of normal gait following DNT for reinnervating common fibular nerve targets. As electrical stimulation has already been proven to be safe in a human patient population, and given that DNTs are performed electively and thus preoperative intervention is possible, delivery of CES in the footdrop patient population may significantly improve the efficacy and reliability in patients undergoing a distal nerve transfer.