Exosomal miR-673-5p from fibroblasts promotes Schwann cell-mediated peripheral neuron myelination by targeting the TSC2/mTORC1/SREBP2 axis

Magnetic mesoporous silica nanoparticles loaded with peptides for the targeted repair of cavernous nerve injury underlying erectile dysfunction

Erectile dysfunction (ED) is a common male sexual disorder characterized by repeated or persistent difficulty in achieving or maintaining an erection. It can arise from various factors, with cavernous nerve injury (CNI) from radical prostatectomy being a predominant cause of iatrogenic ED, posing significant clinical concerns. The complexity of cavernous tissue damage in CNI-induced ED (CNIED) often results in poor efficacy and resistance to conventional vascular ED treatments. To address CNI-induced ED, this study developed a system of magnetic mesoporous silica nanoparticles (MSNs) loaded with peptides for targeted treatment. Core-shell Fe3O4-coated MSNs were used as drug carriers and loaded with RADA16-I/RAD-RGI peptides (PD) to create a neurotrophic microenvironment to treat peripheral nerve defects. Furthermore, the neuro-targeting peptide HLNILSTLWKYR (PT) was grafted onto MSNs. The in vivo therapeutic effect was evaluated using a rat bilateral cavernous nerve injury (BCNI) model. The results showed that the neuro-targeted Fe3O4@SiO2-PT-PD nanoparticles significantly promoted regeneration of the cavernous nerve and restored erectile function. This promising strategy offers significant clinical potential for treating CNI-induced ED. Nanomedicine technology has the potential to not only improve treatment outcomes but also reduce side effects in healthy cells, paving the way for more accurate targeted repair of cavernous nerve damage.

The phenotypic changes of Schwann cells promote the functional repair of nerve injury

Functional recovery after nerve injury is a significant challenge due to the complex nature of nerve injury repair and the non-regeneration of neurons. Schwann cells (SCs), play a crucial role in the nerve injury repair process because of their high plasticity, secretion, and migration abilities. Upon nerve injury, SCs undergo a phenotypic change and redifferentiate into a repair phenotype, which helps in healing by recruiting phagocytes, removing myelin fragments, promoting axon regeneration, and facilitating myelin formation. However, the repair phenotype can be unstable, limiting the effectiveness of the repair. Recent research has found that transplantation of SCs can be an effective treatment option, therefore, it is essential to comprehend the phenotypic changes of SCs and clarify the related mechanisms to develop the transplantation therapy further.

RNA sequencing of exosomes secreted by fibroblast and Schwann cells elucidates mechanisms underlying peripheral nerve regeneration

JOURNAL/nrgr/04.03/01300535-202408000-00035/figure1/v/2023-12-16T180322Z/r/image-tiff Exosomes exhibit complex biological functions and mediate a variety of biological processes, such as promoting axonal regeneration and functional recovery after injury. Long non-coding RNAs (lncRNAs) have been reported to play a crucial role in axonal regeneration. However, the role of the lncRNA-microRNA-messenger RNA (mRNA)-competitive endogenous RNA (ceRNA) network in exosome-mediated axonal regeneration remains unclear. In this study, we performed RNA transcriptome sequencing analysis to assess mRNA expression patterns in exosomes produced by cultured fibroblasts (FC-EXOs) and Schwann cells (SC-EXOs). Differential gene expression analysis, Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis, and protein-protein interaction network analysis were used to explore the functions and related pathways of RNAs isolated from FC-EXOs and SC-EXOs. We found that the ribosome-related central gene Rps5 was enriched in FC-EXOs and SC-EXOs, which suggests that it may promote axonal regeneration. In addition, using the miRWalk and Starbase prediction databases, we constructed a regulatory network of ceRNAs targeting Rps5, including 27 microRNAs and five lncRNAs. The ceRNA regulatory network, which included Ftx and Miat, revealed that exsosome-derived Rps5 inhibits scar formation and promotes axonal regeneration and functional recovery after nerve injury. Our findings suggest that exosomes derived from fibroblast and Schwann cells could be used to treat injuries of peripheral nervous system.

[MiR-132-3p negatively regulates CAMTA1 to promote Schwann cell proliferation and migration and alleviates I-125 seeds-induced exacerbation of facial nerve injury in rats]

OBJECTIVE

To investigate the regulatory effect of miR-132-3p on calmodulin-binding transcription activator 1 (CAMTA1) and Schwann cell activity in rats with facial nerve injury (FNI) treated with I-125 seeds.

METHODS

Rat Schwann cells were irradiated with I-125 seeds and transfected with miR-132-3p mimic, miR-132-3p inhibitor or sh-CAMTA1. The expressions of S100B and β-tubulin Ⅲ in the cells were detected with immunofluorescence assay, and the expressions of miR-132-3p and CAMTA1 protein were determined using RT-qPCR and Western blotting, respectively. EdU staining and Transwell assay were used to evaluate the changes in cell proliferation and migration ability. In a rat model of FNI, I-125 seeds were implanted into the facial tissues near the facial nerve 2 weeks before modeling, and miR-132-3p mimic was injected subcutaneously in the face after modeling. The pathologies of the facial nerve was assessed by HE, LFB and immunofluorescence staining. The targeting relationship between miR-132-3p and CAMTA1 was verified using StarBase v2.0 database and dual-luciferase reporter assay.

RESULTS

Rat Schwann cells showed high expressions of S100B and β-tubulin Ⅲ. I-125 seeds radiation significantly decreased miR-132-3p expression and repressed proliferation and migration of the cells (P < 0.001). Overexpression of miR-132-3p or CAMTA1 knockdown obviously enhanced proliferation and migration of the Schwann cells, while miR-132-3p knockdown produced the opposite effect. MiR-132-3p negatively regulated CAMTA1 expression. In the rat models of FNI, miR-132-3p injection significantly inhibited CAMTA1 expression and attenuated I-125 seeds-induced exacerbation of FNI.

CONCLUSION

Overexpression of miR-132-3p suppresses CAMTA1 expression and promotes Schwann cell proliferation and migration to alleviate I-125 seeds-induced exacerbation of FNI in rats.

Emerging role of extracellular vesicles and exogenous stimuli in molecular mechanisms of peripheral nerve regeneration

Peripheral nerve injuries lead to significant morbidity and adversely affect quality of life. The peripheral nervous system harbors the unique trait of autonomous regeneration; however, achieving successful regeneration remains uncertain. Research continues to augment and expedite successful peripheral nerve recovery, offering promising strategies for promoting peripheral nerve regeneration (PNR). These include leveraging extracellular vesicle (EV) communication and harnessing cellular activation through electrical and mechanical stimulation. Small extracellular vesicles (sEVs), 30-150 nm in diameter, play a pivotal role in regulating intercellular communication within the regenerative cascade, specifically among nerve cells, Schwann cells, macrophages, and fibroblasts. Furthermore, the utilization of exogenous stimuli, including electrical stimulation (ES), ultrasound stimulation (US), and extracorporeal shock wave therapy (ESWT), offers remarkable advantages in accelerating and augmenting PNR. Moreover, the application of mechanical and electrical stimuli can potentially affect the biogenesis and secretion of sEVs, consequently leading to potential improvements in PNR. In this review article, we comprehensively delve into the intricacies of cell-to-cell communication facilitated by sEVs and the key regulatory signaling pathways governing PNR. Additionally, we investigated the broad-ranging impacts of ES, US, and ESWT on PNR.

Advancing neural regeneration via adaptable hydrogels: Enriched with Mg2+ and silk fibroin to facilitate endogenous cell infiltration and macrophage polarization

Peripheral nerve injury is a complex and challenging medical condition due to the limited ability of nerves to regenerate, resulting in the loss of both sensory and motor function. Hydrogels have emerged as a promising biomaterial for promoting peripheral nerve regeneration, while conventional hydrogels are generally unable to support endogenous cell infiltration due to limited network dynamics, thereby compromising the therapeutic outcomes. Herein, we present a cell adaptable hydrogel containing a tissue-mimetic silk fibroin network and a dynamically crosslinked bisphosphonated-alginate network. The dynamic network of this hydrogel can respond to cell-generated forces to undergo the cell-mediated reorganization, thereby effectively facilitating the rapid infiltration of Schwann cells and macrophages, as well as the ingrowth of axons. We further show that the magnesium ions released from the hydrogel not only promote neurite outgrowth but also regulate the polarization of macrophages in a sequential manner, contributing to the formation of a regenerative microenvironment. Therefore, this hydrogel effectively prevents muscle atrophy and promotes the regeneration and functional recovery of nerve defects of up to 10 mm within 8 weeks. The findings from this study demonstrate that adaptable hydrogels are promising inductive biomaterials for enhancing the therapeutic outcomes of peripheral nerve injury treatments.

LIPUS-SCs-Exo promotes peripheral nerve regeneration in cavernous nerve crush injury-induced ED rats via PI3K/Akt/FoxO signaling pathway

OBJECTIVE

Clinical treatment of erectile dysfunction (ED) caused by cavernous nerve (CN) injury during pelvic surgery is difficult. Low-intensity pulsed ultrasound (LIPUS) can be a potential strategy for neurogenic ED (NED). However, whether Schwann cells (SCs) can respond to LIPUS stimulation signals is unclear. This study aims to elucidate the signal transmission between SCs paracrine exosome (Exo) and neurons stimulated by LIPUS, as well as to analyze the role and potential mechanisms of exosomes in CN repair after injury.

METHODS

The major pelvic ganglion (MPG) neurons and MPG/CN explants were stimulated with LIPUS of different energy intensities to explore the appropriate LIPUS energy intensity. The exosomes were isolated and purified from LIPUS-stimulated SCs (LIPUS-SCs-Exo) and non-stimulated SCs (SCs-Exo). The effects of LIPUS-SCs-Exo on neurite outgrowth, erectile function, and cavernous penis histology were identified in bilateral cavernous nerve crush injury (BCNI)-induced ED rats.

RESULTS

LIPUS-SCs-Exo group can enhance the axon elongation of MPG/CN and MPG neurons compared to SCs-Exo group in vitro. Then, the LIPUS-SCs-Exo group showed a stronger ability to promote the injured CN regeneration and SCs proliferation compared to the SCs-Exo group in vivo. Furthermore, the LIPUS-SCs-Exo group increased the Max intracavernous pressure (ICP)/mean arterial pressure (MAP), lumen to parenchyma and smooth muscle to collagen ratios compared to the SCs-Exo group in vivo. Additionally, high-throughput sequencing combined with bioinformatics analysis revealed the differential expression of 1689 miRNAs between the SCs-Exo group and the LIPUS-SCs-Exo group. After LIPUS-SCs-Exo treatment, the phosphorylated levels of Phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt) and forkhead box O (FoxO) in MPG neurons increased significantly compared to negative control (NC) and SCs-Exo groups.

CONCLUSION

Our study revealed that LIPUS stimulation could regulate the gene of MPG neurons by changing miRNAs derived from SCs-Exo, then activating the PI3K-Akt-FoxO signal pathway to enhance nerve regeneration and restore erectile function. This study had important theoretical and practical significance for improving the NED treatment.

Exosomal noncoding RNA-mediated spatiotemporal regulation of lipid metabolism: Implications in immune evasion and chronic inflammation

The hallmark of chronic inflammatory diseases is immune evasion. Successful immune evasion involves numerous mechanisms to suppress both adaptive and innate immune responses. Either direct contact between cells or paracrine signaling triggers these responses. Exosomes are critical drivers of these interactions and exhibit both immunogenic and immune evasion properties during the development and progression of various chronic inflammatory diseases. Exosomes carry diverse molecular cargo, including lipids, proteins, and RNAs that are crucial for immunomodulation. Moreover, recent studies have revealed that exosomes and their cargo-loaded molecules are extensively involved in lipid remodeling and metabolism during immune surveillance and disease. Many studies have also shown the involvement of lipids in controlling immune cell activities and their crucial upstream functions in regulating inflammasome activation, suggesting that any perturbation in lipid metabolism results in abnormal immune responses. Strikingly, the expanded immunometabolic reprogramming capacities of exosomes and their contents provided insights into the novel mechanisms behind the prophylaxis of inflammatory diseases. By summarizing the tremendous therapeutic potential of exosomes, this review emphasizes the role of exosome-derived noncoding RNAs in regulating immune responses through the modulation of lipid metabolism and their promising therapeutic applications.

Fibroblast exosomal TFAP2C induced by chitosan oligosaccharides promotes peripheral axon regeneration via the miR-132-5p/CAMKK1 axis

Chitosan and its degradation product, oligosaccharides, have been shown to facilitate peripheral nerve regeneration. However, the underlying mechanisms are not well understood. In this study, we analyzed the protein expression profiles in sciatic nerves after injury using proteomics. A group of proteins related to exosome packaging and transport is up-regulated by chitosan oligosaccharides (COS), implying that exosomes are involved in COS-induced peripheral nerve regeneration. In fact, exosomes derived from fibroblasts (f-EXOs) treated with COS significantly promoted axon extension and regeneration. Exosomal protein identification and functional studies, revealed that TFAP2C is a key factor in neurite outgrowth induced by COS-f-EXOs. Furthermore, we showed that TFAP2C targets the pri-miRNA-132 gene and represses miR-132-5p expression in dorsal root ganglion neurons. Camkk1 is a downstream substrate of miR-132-5p that positively affects axon extension. In rats, miR-132-5p antagomir stimulates CAMKK1 expression and improves axon regeneration and functional recovery in sciatic nerves after injury. Our data reveal the mechanism for COS in axon regeneration, that is COS induce fibroblasts to produce TFAP2C-enriched EXOs, which are then transferred into axons to promote axon regeneration via miR-132-5p/CAMKK1. Moreover, these results show a new facet of fibroblasts in axon regeneration in peripheral nerves.

The Exosome-Mediated PI3K/Akt/mTOR Signaling Pathway in Neurological Diseases

As major public health concerns associated with a rapidly growing aging population, neurodegenerative diseases (NDDs) and neurological diseases are important causes of disability and mortality. Neurological diseases affect millions of people worldwide. Recent studies have indicated that apoptosis, inflammation, and oxidative stress are the main players of NDDs and have critical roles in neurodegenerative processes. During the aforementioned inflammatory/apoptotic/oxidative stress procedures, the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway plays a crucial role. Considering the functional and structural aspects of the blood-brain barrier, drug delivery to the central nervous system is relatively challenging. Exosomes are nanoscale membrane-bound carriers that can be secreted by cells and carry several cargoes, including proteins, nucleic acids, lipids, and metabolites. Exosomes significantly take part in the intercellular communications due to their specific features including low immunogenicity, flexibility, and great tissue/cell penetration capabilities. Due to their ability to cross the blood-brain barrier, these nano-sized structures have been introduced as proper vehicles for central nervous system drug delivery by multiple studies. In the present systematic review, we highlight the potential therapeutic effects of exosomes in the context of NDDs and neurological diseases by targeting the PI3K/Akt/mTOR signaling pathway.

Combinational treatments of RNA interference and extracellular vesicles in the spinocerebellar ataxia

Spinocerebellar ataxia (SCA) is an autosomal dominant neurodegenerative disease (ND) with a high mortality rate. Symptomatic treatment is the only clinically adopted treatment. However, it has poor effect and serious complications. Traditional diagnostic methods [such as magnetic resonance imaging (MRI)] have drawbacks. Presently, the superiority of RNA interference (RNAi) and extracellular vesicles (EVs) in improving SCA has attracted extensive attention. Both can serve as the potential biomarkers for the diagnosing and monitoring disease progression. Herein, we analyzed the basis and prospect of therapies for SCA. Meanwhile, we elaborated the development and application of miRNAs, siRNAs, shRNAs, and EVs in the diagnosis and treatment of SCA. We propose the combination of RNAi and EVs to avoid the adverse factors of their respective treatment and maximize the benefits of treatment through the technology of EVs loaded with RNA. Obviously, the combinational therapy of RNAi and EVs may more accurately diagnose and cure SCA.