Induce Nerve Regeneration Research Articles

Bioactive MgO/MgCO3/Polycaprolactone Multi-gradient Fibers Facilitate Peripheral Nerve Regeneration by Regulating Schwann Cell Function and Activating Wingless/Integrase-1 Signaling

AbstractPeripheral nerve defects present complex orthopedic challenges with limited efficacy of clinical interventions. The inadequate proliferation and dysfunction of Schwann cells within the nerve scaffold impede the effectiveness of nerve repair. Our previous studies suggested the effectiveness of a magnesium-encapsulated bioactive hydrogel in repairing nerve defects. However, its rapid release of magnesium ions limited its efficacy to long-term nerve regeneration, and its molecular mechanism remains unclear. This study utilized electrospinning technology to fabricate a MgO/MgCO3/polycaprolactone (PCL) multi-gradient nanofiber membrane for peripheral nerve regeneration. Our findings indicated that by carefully adjusting the concentration or proportion of rapidly degradable MgO and slowly degradable MgCO3, as well as the number of electrospun layers, the multi-gradient scaffold effectively sustained the release of Mg2+ over a period of 6 weeks. Additionally, this study provided insight into the mechanism of Mg2+-induced nerve regeneration and confirmed that Mg2+ effectively promoted Schwann cell proliferation, migration, and transition to a repair phenotype. By employing transcriptome sequencing technology, the study identified the Wingless/integrase-1 (Wnt) signaling pathway as a crucial mechanism influencing Schwann cell function during nerve regeneration. After implantation in 10 mm critically sized nerve defects in rats, the MgO/MgCO3/PCL multi-gradient nanofiber combined with a 3D-engineered PCL nerve conduit showed enhanced axonal regeneration, remyelination, and reinnervation of muscle tissue 12 weeks post-surgery. In conclusion, this study successfully developed an innovative multi-gradient long-acting MgO/MgCO3/PCL nanofiber with a tunable Mg2+ release property, which underscored the molecular mechanism of magnesium-encapsulated biomaterials in treating nervous system diseases and established a robust theoretical foundation for future clinical translation. Graphical abstract

Reprogramming metabolic microenvironment for nerve regeneration via waterborne polylactic acid-polyurethane copolymer scaffolds

Cell metabolism, as the key driver of inflammation, revascularization and even subsequent tissue regeneration, is controlled by and also conversely influenced by signal transduction. Incorporation of cell metabolism into tissue engineering research holds immense potential for in-situ treatment repair and further understanding of the host-biomaterial cues in body response. In this study, an anti-inflammatory waterborne polyurethane scaffold incorporated with poly-l-lactic acid (PLLA) block was served to repair nerve injuries (LAx-WPU). Lactate was released through the degradation of LAx-WPU scaffolds, and the content increased with the addition of PLLA block over the degradation times. Thenceforth, the production of adenosine triphosphate (ATP) in primary neurons and neuronal axon growth were achieved by taking up lactate through monocarboxylate transporters (MCT2) for energy metabolism under glucose-free environment treated with LAx-WPU degradation solution. After LAx-WPU was implanted to repair brain nerve defects in rats, filamentous neurons elongation, rapid vascularization, and nerve tissue regeneration were realized up to 28 days with the positive expression of microtubule-associated protein (MAP2), β-tubulin (Tuj1), and platelet endothelial cell adhesion molecule (CD31) in the scaffolds. Results highlighted that the LAx-WPU scaffolds up-regulated not only the ATP-ADP-AMP purine metabolism compounds to mainly bridge neuroactive ligand-receptor interaction genes, cAMP pathway genes, and calcium pathway genes for neurocytes but also the ATP-GMP purine metabolism to angiogenesis in Gene Ontology (GO) analysis. Further analysis in reverse showed axonal regeneration is restrained by the inhibition of MCT2, proving LAx-WPU promoted nerve repair depended on lactate for energy. Therefore, LAx-WPU scaffolds construct an expected way to modulate the metabolic microenvironment for inducing nerve regeneration by intrinsic biomaterial metabolism cues without any bioactive factors.

Pulsed electromagnetic field-assisted reduced graphene oxide composite 3D printed nerve scaffold promotes sciatic nerve regeneration in rats

Peripheral nerve injuries can lead to sensory or motor deficits that have a serious impact on a patient’s mental health and quality of life. Nevertheless, it remains a major clinical challenge to develop functional nerve conduits as an alternative to autologous grafts. We applied reduced graphene oxide (rGO) as a bioactive conductive material to impart electrophysiological properties to a 3D printed scaffold and the application of a pulsed magnetic field to excite the formation of microcurrents and induce nerve regeneration. In vitro studies showed that the nerve scaffold and the pulsed magnetic field made no effect on cell survival, increased S-100β protein expression, enhanced cell adhesion, and increased the expression level of nerve regeneration-related mRNAs. In vivo experiments suggested that the protocol was effective in promoting nerve regeneration, resulting in functional recovery of sciatic nerves in rats, when they were damaged close to that of the autologous nerve graft, and increased expression of S-100β, NF200, and GAP43. These results indicate that rGO composite nerve scaffolds combined with pulsed magnetic field stimulation have great potential for peripheral nerve rehabilitation.

Oxidation-treated carbon nanotube yarns accelerate neurite outgrowth and induce axonal regeneration in peripheral nerve defect

Carbon nanotubes (CNTs) have the potential to promote peripheral nerve regeneration, although with limited capacity and foreign body reaction. This study investigated whether CNTs hydrophilized by oxidation can improve peripheral nerve regeneration and reduce foreign body reactions and inflammation. Three different artificial nerve conduit models were created using CNTs treated with ozone (O group), strong acid (SA group), and untreated (P group). They were implanted into a rat sciatic nerve defect model and evaluated after 8 and 16 weeks. At 16 weeks, the SA group showed significant recovery in functional and electrophysiological evaluations compared with the others. At 8 weeks, histological examination revealed a significant increase in the density of regenerated neurofilament and decreased foreign body giant cells in the SA group compared with the others. Oxidation-treated CNTs improved biocompatibility, induced nerve regeneration, and inhibited foreign-body reactions.

Silicone rubber sealed channel induced self-healing of large bone defects: Where is the limit of self-healing of bone?

BackgroundLarge defects of long tubular bones due to severe trauma, bone tumor resection, or osteomyelitis debridement are challenging in orthopedics. Bone non-union and other complications often lead to serious consequences. At present, autologous bone graft is still the gold standard for the treatment of large bone defects. However, autologous bone graft sources are limited. Silicon rubber (SR) materials are widely used in biomedical fields, due to their safety and biocompatibility, and even shown to induce nerve regeneration. Materials and methodsWe extracted rat bone marrow mesenchymal stem cells (BMMSCs) in vitro and verified the biocompatibility of silicone rubber through cell experiments. Then we designed a rabbit radius critical sized bone defect model to verify the effect of silicone rubber sealed channel inducing bone repair in vivo. ResultsSR sealed channel could prevent the fibrous tissue from entering the fracture end and forming bone nonunion, thereby inducing self-healing of long tubular bone through endochondral osteogenesis. The hematoma tissue formed in the early stage was rich in osteogenesis and angiogenesis related proteins, and gradually turned into vascularization and endochondral osteogenesis, and finally realized bone regeneration. ConclusionsIn summary, our study proved that SR sealed channel could prevent the fibrous tissue from entering the fracture end and induce self-healing of long tubular bone through endochondral osteogenesis. In this process, the sealed environment provided by the SR channel was key, and this might indicate that the limit of self-healing of bone exceeded the previously thought. The translational potential of this articleThis study investigated a new concept to induce the self-healing of large bone defects. It could avoid trauma caused by autologous bone extraction and possible rejection reactions caused by bone graft materials. Further research based on this study, including the innovation of induction materials, might invent a new type of bone inducing production, which could bring convenience to patients. We believed that this study had significant meaning for the treatment of large bone defects in clinical practice.

Enhancement of neural regeneration as a therapeutic strategy for Alzheimer's disease (Review).

Alzheimer's disease (AD), the most common cause of dementia worldwide, has gradually become a global health concern for society and individuals with the process of global ageing. Although extensive research has been carried out on AD, the etiology and pathological mechanism of the disease are still unclear, and there is no specific drug to cure or delay AD progression. The exploration of enhancing nerve regeneration in AD has gradually attracted increasing attention. In the current review, the existing therapeutic strategies were summarized to induce nerve regeneration which can increase the number of neurons, and improve the survival of neurons, the plasticity of synapses and synaptic activity. The strategies include increasing neurotrophic expression (such as brain-derived neurotrophic factor and nerve growth factor), inhibiting acetylcholinesterase (such as donepezil, tacrine, rivastigmine and galanthamine), elevating histone deacetylase levels (such as RGFP-966, Tasquinimod, CM-414 and 44B), stimulating the brain by physiotherapy (such as near-infrared light, repetitive transcranial magnetic stimulation, and transcranial direct current stimulation) and transplanting exogenous neural stem cells. However, further evaluations need to be performed to determine the optimal treatment. The present study reviews recent interventions for enhancing adult neurogenesis and attempts to elucidate their mechanisms of action, which may provide a theoretical basis for inducing nerve regeneration to fight against AD.

Modified black phosphorus quantum dots promotes spinal cord injury repair by targeting the AKT signaling pathway

Spinal cord injury (SCI) is a serious refractory disease of the central nervous system (CNS), which mostly caused by high-energy trauma. Existing interventions such as hormone shock and surgery are insufficient options, which relate to the secondary inflammation and neuronal dysfunction. Hydrogel with neuron-protective behaviors attracts tremendous attention, and black phosphorus quantum dots (BPQDs) encapsulating with Epigallocatechin-3-gallate (EGCG) hydrogels (E@BP) is designed for inflammatory modulation and SCI treatment in this study. E@BP displays good stability, biocompatibility and safety profiles. E@BP incubation alleviates lipopolysaccharide (LPS)-induced inflammation of primary neurons and enhances neuronal regeneration in vitro. Furthermore, E@BP reconstructs structural versus functional integrity of spinal cord tracts, which promotes recovery of motor neuron function in SCI rats after transplantation. Importantly, E@BP restarts the cell cycle and induces nerve regeneration. Moreover, E@BP diminishes local inflammation of SCI tissues, characterized by reducing accumulation of astrocyte, microglia, macrophages, and oligodendrocytes. Indeed, a common underlying mechanism of E@BP regulating neural regenerative and inflammatory responses is to promote the phosphorylation of key proteins related to AKT signaling pathway. Together, E@BP probably repairs SCI by reducing inflammation and promoting neuronal regeneration via the AKT signaling pathway.

Necroptosis plays a crucial role in the exacerbation of retinal injury after blunt ocular trauma.

Retinal injury after blunt ocular trauma may directly affect prognosis and lead to vision loss. To investigate the pathological changes and molecular mechanisms involved in retinal injury after blunt ocular trauma, we established a weight drop injury model of blunt ocular trauma in male Beagle dogs. Hematoxylin-eosin staining, immunofluorescence staining, western blotting, and TUNEL assays were performed to investigate retinal injury within 14 days after blunt ocular trauma. Compared with the control group, the thicknesses of the inner and outer nuclear layers, as well as the number of retinal ganglion cells, gradually decreased within 14 days after injury. The number of bipolar cells in the inner nuclear layer began to decrease 1 day after injury, while the numbers of cholinergic and amacrine cells in the inner nuclear layer did not decrease until 7 days after injury. Moreover, retinal cell necroptosis increased with time after injury; it progressed from the ganglion cell layer to the outer nuclear layer. Visual electrophysiological findings indicated that visual impairment began on the first day after injury and worsened over time. Additionally, blunt ocular trauma induced nerve regeneration and Müller glial hyperplasia; it also resulted in the recruitment of microglia to the retina and polarization of those microglia to the M1 phenotype. These findings suggest that necroptosis plays an important role in exacerbating retinal injury after blunt ocular trauma via gliosis and neuroinflammation. Such a role has important implications for the development of therapeutic strategies.

Nerve Regeneration Effect of a Composite Bioactive Carboxymethyl Chitosan-Based Nerve Conduit with a Radial Texture.

Chitosan (CTS) has been used as a nerve guidance conduit (NGC) material for bridging peripheral nerve defects due to its biocompatible, biodegradable, and non-toxic properties. However, the nerve regeneration effect of chitosan alone is restricted due to its inadequate biological activity. Herein, a composite, bioactive chitosan based nerve conduit, consisting of outer warp-knitted tube scaffold made from medical-grade chitosan fiber, and inner porous cross linked carboxymethyl chitosan (C-CM-CTS) sponge with radial texture was developed. The inner wall of the scaffold was coated with C-CM-CTS solution. CM-CTS provided favorable bioactivities in the composite chitosan-based nerve conduit. An in vitro study of CM-CTS revealed its satisfying biocompatibility with fibroblast and its inhibition of oxidative damage to Schwann cells. As the internal filler of the NGC, the lyophilized sponge of C-CM-CTS showed a longitudinal guidance effect for nerve reconstruction. After 10 mm defect in rat sciatic nerve was bridged with the composite bioactive chitosan-based nerve conduit, the nerve conduit was able to effectively promote axonal regeneration and played a positive role in inducing nerve regeneration and functional recovery. In addition to the functional advantages, which are equal to those of an autograft; the technology for the preparation of this conduit can be put into mass production.

A Bioactive and Photoresponsive Platform for Wireless Electrical Stimulation to Promote Neurogenesis.

Delivering electrical signals to neural cells and tissue has attracted increasing attention in the treatment of nerve injuries. Unlike traditional wired electrical stimulation, wireless and remote light stimulation provides less invasive and longer-lasting interfaces, holding great promise in the treatment of nerve injuries and neurodegenerative diseases, as well as human-computer interaction. Additionally, a bioactive matrix that bridges the injured gap and induces nerve regeneration is essential for injured nerve repair. However, it is still challenging to construct a 3D biomimetic cell niche with optoelectrical responsiveness. Herein, a bioactive platform for remote and wireless optoelectrical stimulation is established by incorporating hydrophilic poly(3-hexylthiophene) nanoparticles (P3HT NPs) into a biomimetic hydrogel matrix. Moreover, the hydrogel matrix is modified by varying the composition and/or the crosslinking degree to meet the needs of different application scenarios. When exposed to pulsed green light, P3HT NPs in hydrogels convert light signals into electrical signals, resulting in the generation of tens of picoampere photocurrent, which is proved to promote the growth of cortical neurons that covered by hydrogels and the neuronal differentiation of bone marrow mesenchymal stem cells (BMSCs) encapsulated in hydrogels. This work is of great significance for the design of next-generation neural electrodes and scaffolds.

Filtrated bone marrow-derived stem cell lysate may improve erectile function through nerve regeneration in a rat model of cavernous nerve injury

ABSTRACT Introduction Oral phosphodiesterase-5 (PDE5) inhibitors and intracavernous injection of prostaglandin E1 (PGE1) are common therapies for erectile dysfunction (ED) following radical prostatectomy (RP). However, these treatments are not always effective, and the development of a novel and effective therapy for ED following RP is required. Recently, mesenchymal stem cell (MSC) transplantation was shown to induce nerve regeneration and improves erectile function in a rat model of bilateral cavernous nerve injury (BCNI), a routinely used animal model of RP. Thus, MSCs are expected to be a novel therapy for ED following RP. However, the known risks of stem cell therapy include induction of embolization and immunoreactions. To avert these problems, we explored the suitability of using filtrated stem cell lysate, which contains secreted factors but does not contain MSCs. Objective In this study, we investigated the effects of filtrated bone marrow-derived stem cells lysate (BSCL) on erectile function in a rat model of BCNI. We also investigated the neuroregenerative effects of BSCL using the major pelvic ganglia (MPG) of rats. Methods Bone marrow-derived stem cells were obtained from Wistar/ST rats. After culturing two or three passages, these cells were collected and diluted with phosphate buffered saline (PBS). We obtained BSCL by freeze fracturing and filtrating them. Two experiments were performed. Experiment I: Eight-week-old male Wistar/ST rats were divided into three groups: Sham+PBS (n=8), BCNI+PBS (n=8), and BCNI+BSCL (n=8). Rats in the Sham+PBS group underwent sham surgery as a control. Rats in the BCNI+PBS group underwent complete BCNI surgery. After both surgeries, PBS was injected into the corpus cavernosum. Rats in the BCNI+BSCL group also underwent BCNI surgery, but after surgery, BSCL was injected into the corpus cavernosum. After 4 weeks, erectile function was evaluated by measuring intracavernosal pressure (ICP)/mean arterial pressure (MAP) under stimulation of the cavernous nerve. Experiment II: the MPG were dissected from ten-week-old male Wistar/ST rats. The MPG were placed on Matrigel and incubated with PBS (n=4), BSCL (n=4), or vascular endothelial growth factor (VEGF) (n=4), which was used as a positive control. After 48 h, neurite outgrowth was measured using a z-stack microscope. Results ICP/MAP in the BCNI+PBS group was significantly lower than that in the Sham+PBS group (P<0.05), and ICP/MAP in the BCNI+BSCL group was significantly higher than that in the BCNI+PBS group (P<0.05). MPG treated with BSCL and VEGF had longer neurite outgrowth than those treated with PBS. Conclusions BSCL treatment improved erectile function in the BCNI rat model of RP. BSCL also exhibited neuroregenerative effects on rat MPG. This suggests that BSCL may regenerate a crushed cavernous nerve, which results in improved erectile function. Our findings suggest that BSCL may be a new approach for post-RP ED. Further study should be conducted to identify the active factors in BSCL. Disclosure Work supported by industry: no.

Liraglutide Treatment Does Not Induce Changes in the Peripapillary Retinal Nerve Fiber Layer Thickness in Patients with Diabetic Retinopathy.

Purpose: Liraglutide treatment has shown promising anti-inflammatory and nerve regenerative results in preclinical and clinical trials. We sought to assess if liraglutide treatment would induce nerve regeneration through its anti-inflammatory and neurotrophic mechanisms by increasing peripapillary retinal nerve fiber layer (RNFL) thickness in individuals with long-term type 1 diabetes. Methods: Secondary analyses were performed on a prospective, double-blinded, randomized, placebo-controlled trial on adults with type 1 diabetes, distal symmetric polyneuropathy (DSPN), and confirmed diabetic retinopathy, who were randomized 1:1 to either 26 weeks placebo or liraglutide treatment. The primary endpoint was a change in peripapillary RNFL thickness between treatments, assessed by optical coherence tomography. Results: Thirty-seven participants were included in the secondary analysis. No differences in mean peripapillary RNFL thickness (overall ΔMean RNFL thickness; liraglutide -1 (±8) μm (-1%) vs. placebo -1 (±5) μm (-1%), P = 0.78, n = 37) or any of the quadrants. Peripapillary RNFL thicknesses were shown between treatments in either nonproliferative (ΔMean RNFL thickness; liraglutide -1 (±5) μm (-1%) vs. placebo 0 (±4) μm (0%), P = 0.80, N = 26) or proliferative diabetic retinopathy subgroup (ΔMean RNFL thickness; liraglutide -2 (±14) μm (-3%) vs. placebo -1 (±6) μm (-2%), P = 0.88, N = 11). Conclusions: In this study, 26 weeks of liraglutide treatment did not induce measurable changes in the assessed optic nerve thickness. Thus, this methodology does not support the induction of substantial nerve regeneration in this cohort with established retinopathy and DSPN. The trial was approved by the Danish Health and Medicines Authority. Informed consent was obtained from all participants. TODINELI study: EUDRA CT: 2013-004375-12, Ethics Ref: N-20130077 Clinical trial registration number: clinicaltrials.gov NCT02138045.

Sensory Reinnervation With Subcutaneously Embedded Innervated Flaps: An Experimental Study in Rats.

In breast reconstruction, both aesthetic outcomes and sensory function are important for postoperative quality of life. Innervated flaps are useful in reconstruction after conventional mastectomy (CM), which leaves a large portion of the skin paddle exposed on the body surface. However, whether they are also useful in skin-sparing mastectomy (SSM) and nipple-sparing mastectomy (NSM) remains unclear. This study aimed to examine the usefulness of innervated flaps in restoring sensation after SSM and NSM using a rat model. Dorsal cutaneous nerves of rats were entirely eliminated except for the medial branch of the dorsal cutaneous nerve of thoracic segment 13, resulting in an innervated field surrounded by a denervated field. The innervated field was elevated as an innervated island flap and then subcutaneously embedded, with the skin paddle deepithelialized entirely (NSM group, n = 5) or except at the center (SSM group, n = 6). In the control model (CM group, n = 5), the flap was sutured back into its original position. Postoperative changes in the mechanonociceptive field were evaluated using the cutaneous trunci muscle reflex test. Immunohistochemical evaluation of regenerated nerves in the new mechanonociceptive field was performed at postoperative week 12. In the SSM and CM groups, the mechanonociceptive field expanded around the skin paddle. In the NSM group, a new mechanonociceptive field appeared at postoperative week 4 and expanded thereafter. Areas of the mechanonociceptive field at postoperative week 12 did not differ significantly between the SSM and NSM groups, but were significantly smaller compared with the CM group and comparable to original flap areas. Histologically, S100- and PGP9.5-positive nerve fibers were observed in the dermis of the new mechanonociceptive field and subcutaneous flap tissue. Subcutaneously embedded innervated island flaps induced nerve regeneration and sensory reinnervation of the denervated skin, suggesting that innervated flaps may also be useful in reconstruction post-SSM/NSM.

Electrospinning Multilayered Scaffolds Loaded with Melatonin and Fe3O4 Magnetic Nanoparticles for Peripheral Nerve Regeneration

AbstractPeripheral nerve injury is a common clinical problem bringing heavy burden to patients, due to its high incidence and unsatisfactory treatment. Nerve guidance conduit (NGC) is a promising scaffold for peripheral nerve repair, and bioactive agents are applied for great functional recovery. Melatonin (MLT) and Fe3O4 magnetic nanoparticles (Fe3O4‐MNPs) are proven to inhibit oxidative stress, inflammation, and induce nerve regeneration. Herein, a multilayered composite NGC loaded with MLT and Fe3O4‐MNPs is designed for sequential and sustainable drug release, creating an appropriate microenvironment for nerve regeneration. The composite scaffold shows sufficient mechanical strength and biocompatibility in vitro, and evidently promotes morphological, functional, and electrophysiological recovery of regenerated sciatic nerves in vivo. This work proves that the multilayered conduits show great prospect in the long‐term nerve defects treatment due to easy manufacture and desired efficacy.

Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse–Associated Cavernous Nerve Regeneration

BackgroundNeurogenic erectile dysfunction (ED) is often refractory to treatment because of insufficient functional nerve recovery after injury or insult. Noninvasive mechano-biological intervention, such as microenergy acoustic pulse (MAP), low-intensity pulsed ultrasound, and low-intensity extracorporeal shockwave treatment, is an optimal approach to stimulate nerve regeneration. AimTo establish a new model in vitro to simulate nerve injury in neurogenic ED and to explore the mechanisms of MAP in vitro. MethodsSprague-Dawley rats were used to isolate Schwann cells (SCs), major pelvic ganglion (MPG), and cavernous nerve with MPG (CN/MPG). SCs were then treated with MAP (0.033 mJ/mm2, 1 Hz, 100 pulses), and SC exosomes were isolated. The MPG and CN/MPG were treated with MAP (0.033 mJ/mm2, 1 Hz) at different dosages (25, 50, 100, 200, or 300 pulses) or exosomes derived from MAP-treated SCs in vitro. OutcomesNeurite growth from the MPG fragments and CN was photographed and measured. Expression of neurotropic factors (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) was checked. ResultsNeurite outgrowth from MPG and CN/MPG was enhanced by MAP in a dosage response manner, peaking at 100 pulses. MAP promoted SC proliferation, neurotropic factor (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) expression, and exosome secretion. SC-derived exosomes significantly enhanced neurite outgrowth from MPG in vitro. Clinical ImplicationsMAP may have utility in the treatment of neurogenic ED by SC-derived exosomes. Strength & LimitationsWe confirmed that MAP enhances penile nerve regeneration through exsomes. Limitations of this study include that our study did not explore the exact mechanisms of how MAP increases SC exosome secretion nor whether MAP modulates the content of exosomes. ConclusionThis study revealed that neurite outgrowth from MPG was enhanced by MAP and by SC-derived exosomes which were isolated after MAP treatment. Our findings indicate that one mechanism by which MAP induces nerve regeneration is by stimulation of SCs to secrete exosomes.Peng D, Reed-Maldonado AB, Zhou F, et al. Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse–Associated Cavernous Nerve Regeneration. J Sex Med 2020;17:1618–1628.

HP-1-4 Filtrated Bone Marrow-Derived Mesenchymal Stem Cell Lysate Improves Erectile Function in a Rat Model of Cavernous Nerve Injury

Oral phosphodiesterase-5 (PDE5) inhibitors and intracavernous injection of prostaglandin E1 (PGE1) are treatments of choice for post radical prostatectomy (RP) erectile dysfunction (ED). However, these treatments are not necessarily effective and the development of a novel and effective therapy for post RP ED is required. Recently, it was reported that mesenchymal stem cell (MSC) transplantation induces nerve regeneration and improves erectile function in a rat model of bilateral cavernous nerve injury (BCNI). However, unexpected differentiation of the transplanted stem cells is still an issue with this approach. To avert this problem, we explored the suitability of filtrated stem cell lysate (FSCL), which contains secreted factors but does not contain MSCs. In this study, we investigated the effects of FSCL on erectile function in a rat model of BCNI. Eight-week-old male Wistar/ST rats underwent BCNI or sham surgery. After surgery, filtrated adipose-derived stem cell lysate (FADSCL) or filtrated bone marrow-derived stem cell lysate (FBMSCL) was injected into the corpus cavernosum. After 4 weeks, erectile function was evaluated by measuring intracavernosal pressure/mean arterial pressure under stimulation of the cavernous nerve. Proteomic analysis was performed to identify effective factors in FSCL.

Muscarinic Toxin 7 Signals Via Ca2+/Calmodulin-Dependent Protein Kinase Kinase \u03b2 to Augment Mitochondrial Function and Prevent Neurodegeneration

Mitochondrial dysfunction is implicated in a variety of neurodegenerative diseases of the nervous system. Peroxisome proliferator–activated receptor-γ coactivator-1α (PGC-1α) is a regulator of mitochondrial function in multiple cell types. In sensory neurons, AMP-activated protein kinase (AMPK) augments PGC-1α activity and this pathway is depressed in diabetes leading to mitochondrial dysfunction and neurodegeneration. Antimuscarinic drugs targeting the muscarinic acetylcholine type 1 receptor (M1R) prevent/reverse neurodegeneration by inducing nerve regeneration in rodent models of diabetes and chemotherapy-induced peripheral neuropathy (CIPN). Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) is an upstream regulator of AMPK activity. We hypothesized that antimuscarinic drugs modulate CaMKKβ to enhance activity of AMPK, and PGC-1α, increase mitochondrial function and thus protect from neurodegeneration. We used the specific M1R antagonist muscarinic toxin 7 (MT7) to manipulate muscarinic signaling in the dorsal root ganglia (DRG) neurons of normal rats or rats with streptozotocin-induced diabetes. DRG neurons treated with MT7 (100 nM) or a selective muscarinic antagonist, pirenzepine (1 μM), for 24 h showed increased neurite outgrowth that was blocked by the CaMKK inhibitor STO-609 (1 μM) or short hairpin RNA to CaMKKβ. MT7 enhanced AMPK phosphorylation which was blocked by STO-609 (1 μM). PGC-1α reporter activity was augmented up to 2-fold (p < 0.05) by MT7 and blocked by STO-609. Mitochondrial maximal respiration and spare respiratory capacity were elevated after 3 h of exposure to MT7 (p < 0.05). Diabetes and CIPN induced a significant (p < 0.05) decrease in corneal nerve density which was corrected by topical delivery of MT7. We reveal a novel M1R-modulated, CaMKKβ-dependent pathway in neurons that represents a therapeutic target to enhance nerve repair in two of the most common forms of peripheral neuropathy.

Mesenchymal stem cell therapy assisted by nanotechnology: a possible combinational treatment for brain tumor and central nerve regeneration.

Mesenchymal stem cells (MSCs) intrinsically possess unique features that not only help in their migration towards the tumor-rich environment but they also secrete versatile types of secretomes to induce nerve regeneration and analgesic effects at inflammatory sites. As a matter of course, engineering MSCs to enhance their intrinsic abilities is growing in interest in the oncology and regenerative field. However, the concern of possible tumorigenesis of genetically modified MSCs prompted the development of non-viral transfected MSCs armed with nanotechnology for more effective cancer and regenerative treatment. Despite the fact that a large number of successful studies have expanded our current knowledge in tumor-specific targeting, targeting damaged brain site remains enigmatic due to the presence of a blood–brain barrier (BBB). A BBB is a barrier that separates blood from brain, but MSCs with intrinsic features of transmigration across the BBB can efficiently deliver desired drugs to target sites. Importantly, MSCs, when mediated by nanoparticles, can further enhance tumor tropism and can regenerate the damaged neurons in the central nervous system through the promotion of axon growth. This review highlights the homing and nerve regenerative abilities of MSCs in order to provide a better understanding of potential cell therapeutic applications of non-genetically engineered MSCs with the aid of nanotechnology.

3D printing of nerve conduits with nanoparticle-encapsulated RGFP966

Nerve conduits have great promise for bridging peripheral nerve defects that always cause disability. Currently, the clinically used nerve conduits are limited in promoting nerve regeneration, leading to the unsatisfied nerve repair efficiency. In this study, we show a 3D-printed nerve conduit with drug release for promoting nerve regeneration. This nerve conduit with designed structures as well as directional fiber-aligned inner surface is rapidly customized by a digital light processing (DLP) based continuous 3D-printing process. Meanwhile, this conduit containing polymeric nanoparticles that can sustained release RGFP966 to promote the remyelination of Schwann cells by activating PI3K–AKT–ERK signal pathway. Moreover, this nerve conduit is degradable and biocompatible. After implantation, this conduit can efficiently bridge a 10-mm rat sciatic nerve defect, which is comparable to the autograft in inducing nerve regeneration and functional recovery. This work suggests that the 3D-printed hydrogel nerve conduits with local release of RGFP966 could efficiently repair the injured nerves, which could inspire the development of future functional nerve conduits.

The Role of Vascular Endothelial Growth Factor in Diabetic Polyneuropathy

Diabetic polyneuropathy (DPN) is the most common microvascular complication in diabetes mellitus (DM). The nerve fibers injury was caused by the interaction between metabolic and vascular factor. Prolonged hyperglycemia will induce several mechanisms, such as sorbitol pathway, hypoxia, oxidative stress, and increased of advanced glycation end products (AGE). Those mechanisms will trigger the production of vascular endothelial growth factor (VEGF). The production of VEGF in neovascularization was followed by the changes in microvascular structure that were marked by the enhancement of arteriol basal membrane, vein distention, arteriovenous shunting, intimal hyperplasia and hypertrophy, and endothelial fenestration. The VEGF production was a response to the hyperglycemia that was considered related to endotheliopathy and increased vascular permeability. Therefore, VEGF was acknowledged to contribute to hypoxia and acts as a potential proinflammatory substance. Nevertheless, VEGF also was considered to have a neuroprotective activity by its capability to trigger remyelination and neurogenesis. Based on this evidence, VEGF was assumed to have 2 different roles (dual effect) which are first by acting in the pathogenesis of DPN by induced hypoxia, increased vascular permeability, and caused inflammation, and second acts as a protective agent by induced nerve regeneration. This review is aimed to describe the proposed role of VEGF in the pathogenesis of DPN as well as some genetic studies regarding VEGF gene and its association with DPN.