Muscle-targeted hydrodynamic gene introduction of insulin-like growth factor-1 using polyplex nanomicelle to treat peripheral nerve injury

Electrospun PCL Nerve Conduit Filled with GelMA Gel for CNTF and IGF-1 Delivery in Promoting Sciatic Nerve Regeneration in Rat

Neural tissue engineering is an essential strategy to repair long-segment peripheral nerve defects. Modification of the nerve conduit is an effective way to improve the local microenvironment of the injury site and facilitate nerve regeneration. However, the concurrent release of multiple growth cues that regulate the activity of Schwann cells and neurons remains a challenge. The present study involved the fabrication of a composite hydrogel, specifically methacrylate-anhydride gelatin-ciliary neurotrophic factor/insulin-like growth factor-1 (GelMA-CNTF/IGF-1), with the aim of providing a sustained release of CNTF and IGF-1. The GelMA-CNTF/IGF-1 hydrogels exhibited a swelling rate of 10.2% following a 24 h incubation in vitro. In vitro, GelMA hydrogels demonstrated a high degree of efficiency in the sustained release of CNTF and IGF-1 proteins, with a release rate of 85.9% for CNTF and 90.9% for IGF-1 shown at day 28. In addition, the GelMA-CNTF/IGF-1 composite hydrogel promoted the proliferation of Schwann cells and the production of nerve growth factor (NGF), connective tissue growth factor (CTGF), fibronectin, and laminin and also considerably promoted the axonal growth of neurons. Furthermore, GelMA-CNTF/IGF-1 hydrogels were loaded into PCL electrospun nerve conduits to repair 15 mm sciatic nerve defects in rats. In vivo studies indicated that PCL-GelMA-CNTF/IGF-1 could efficiently accelerate the regeneration of the rat sciatic nerve, promote the formation of the myelin sheath of new axons, promote the electrophysiological function of regenerated nerves, and eventually improve the recovery of motor function in rats. Overall, the PCL-GelMA-CNTF/IGF-1 scaffold presents an attractive new approach for generating an optimal therapeutic alternative for peripheral nerve restoration.

Comprehensive Evaluation of Lipid Nanoparticles and Polyplex Nanomicelles for Muscle-Targeted mRNA Delivery

The growing significance of messenger RNA (mRNA) therapeutics in diverse medical applications, such as cancer, infectious diseases, and genetic disorders, highlighted the need for efficient and safe delivery systems. Lipid nanoparticles (LNPs) have shown great promise for mRNA delivery, but challenges such as toxicity and immunogenicity still remain to be addressed. In this study, we aimed to compare the performance of polyplex nanomicelles, our original cationic polymer-based carrier, and LNPs in various aspects, including delivery efficiency, organ toxicity, muscle damage, immune reaction, and pain. Our results showed that nanomicelles (PEG-PAsp(DET)) and LNPs (SM-102) exhibited distinct characteristics, with the former demonstrating relatively sustained protein production and reduced inflammation, making them suitable for therapeutic purposes. On the other hand, LNPs displayed desirable properties for vaccines, such as rapid mRNA expression and potent immune response. Taken together, these results suggest the different potentials of nanomicelles and LNPs, supporting further optimization of mRNA delivery systems tailored for specific purposes.

Hydrodynamic Delivery: Characteristics, Applications, and Technological Advances

The principle of hydrodynamic delivery was initially used to develop a method for the delivery of plasmids into mouse hepatocytes through tail vein injection and has been expanded for use in the delivery of various biologically active materials to cells in various organs in a variety of animal species through systemic or local injection, resulting in significant advances in new applications and technological development. The development of regional hydrodynamic delivery directly supports successful gene delivery in large animals, including humans. This review summarizes the fundamentals of hydrodynamic delivery and the progress that has been made in its application. Recent progress in this field offers tantalizing prospects for the development of a new generation of technologies for broader application of hydrodynamic delivery.

Review of Drug Therapy for Peripheral Facial Nerve Regeneration That Can Be Used in Actual Clinical Practice

Although facial nerve palsy is not a life-threatening disease, facial asymmetry affects interpersonal relationships, causes psychological stress, and devastates human life. The treatment and rehabilitation of facial paralysis has many socio-economic costs. Therefore, in cases of facial paralysis, it is necessary to identify the cause and provide the best treatment. However, until now, complete recovery has been difficult regardless of the treatment used in cases of complete paralysis of unknown cause and cutting injury of the facial nerve due to disease or accident. Therefore, this article aims to contribute to the future treatment of facial paralysis by reviewing studies on drugs that aid in nerve regeneration after peripheral nerve damage.

Regenerative Endodontic Procedures for the Treatment of Necrotic Mature Teeth: A Preliminary Randomised Clinical Trial

AIM

This preliminary randomised, prospective, controlled trial aimed to compare the clinical and radiographic outcomes of two regenerative endodontic procedures (REPs), revitalisation and a platelet-rich fibrin (PRF)-based technique, in the treatment of mature permanent teeth with necrotic pulps.

METHODOLOGY

The trial has been reported according to the Preferred Reporting Items for Randomised Trials in Endodontics 2020 guidelines. The study protocol was registered at the clinical trial registry (ClinicalTrials.gov) with identifier number NCT04158232. Twenty patients with mature necrotic anterior teeth with large periapical lesions were randomly allocated into two groups (n=10): group I, treated with revitalisation with the blood clot (BC) technique, and Group II, treated with a PRF-based technique. The follow-up was for 12 months. Periradicular healing was assessed using standardised radiographs taken at baseline, and at 6 and 12 months after treatment. An electric pulp tester was used to assess whether pulp sensibility had been regained during the follow-up period. Statistical analysis was conducted using Mann-Whitney test and Wilcoxon test for non-parametric data. For parametric data, repeated measures analysis of variance was used. The significance level was set at P≤0.05.

RESULTS

There was a significant increase in periradicular healing in both groups at 6 and 12 months, compared to that at baseline, with no significant difference between the studied groups after 12 months (P=0.143). There was a significant difference between the tooth sensibility readings at baseline, 6-month, and 12-month follow-up timepoints (P<0.001).

CONCLUSIONS

The findings of this preliminary trial indicate the potential for using REPs, such as revitalisation or PRF-based techniques, as treatment options for mature teeth with necrotic pulps. A higher level of evidence obtained through adequately powered clinical trials and longer follow-up periods are required to conclusively validate the different outcomes of REPs.

A Genomic Approach to Delineating the Occurrence of Scoliosis in Arthrogryposis Multiplex Congenita

Arthrogryposis multiplex congenita (AMC) describes a group of conditions characterized by the presence of non-progressive congenital contractures in multiple body areas. Scoliosis, defined as a coronal plane spine curvature of ≥10 degrees as measured radiographically, has been reported to occur in approximately 20% of children with AMC. To identify genes that are associated with both scoliosis as a clinical outcome and AMC, we first queried the DECIPHER database for copy number variations (CNVs). Upon query, we identified only two patients with both AMC and scoliosis (AMC-SC). The first patient contained CNVs in three genes (FBN2, MGF10, and PITX1), while the second case had a CNV in ZC4H2. Looking into small variants, using a combination of Human Phenotype Ontogeny and literature searching, 908 genes linked with scoliosis and 444 genes linked with AMC were identified. From these lists, 227 genes were associated with AMC-SC. Ingenuity Pathway Analysis (IPA) was performed on the final gene list to gain insight into the functional interactions of genes and various categories. To summarize, this group of genes encompasses a diverse group of cellular functions including transcription regulation, transmembrane receptor, growth factor, and ion channels. These results provide a focal point for further research using genomics and animal models to facilitate the identification of prognostic factors and therapeutic targets for AMC.

Insulin-Like Growth Factor-1: A Promising Therapeutic Target for Peripheral Nerve Injury

Patients who sustain peripheral nerve injuries (PNIs) are often left with debilitating sensory and motor loss. Presently, there is a lack of clinically available therapeutics that can be given as an adjunct to surgical repair to enhance the regenerative process. Insulin-like growth factor-1 (IGF-1) represents a promising therapeutic target to meet this need, given its well-described trophic and anti-apoptotic effects on neurons, Schwann cells (SCs), and myocytes. Here, we review the literature regarding the therapeutic potential of IGF-1 in PNI. We appraised the literature for the various approaches of IGF-1 administration with the aim of identifying which are the most promising in offering a pathway toward clinical application. We also sought to determine the optimal reported dosage ranges for the various delivery approaches that have been investigated.

Intraneural IFG-1 in Cryopreserved Nerve Isografts Increase Neural Regeneration and Functional Recovery in the Rat Sciatic Nerve

BACKGROUND

Insulin-like growth factor 1 (IGF-1) was found to stimulate Schwann cell mitosis. Exogenous IGF-1 may improve nerve regeneration after cryopreservation.

OBJECTIVE

To evaulate the effect of intraneural administration of IGF-1 in cryopreserved nerve isografts.

METHODS

Eighteen millimeter grafts were used for bridging an 18-mm defect in the rat sciatic nerve. A total of 57 rats were randomly divided into three groups: (1) autograft (Group 1); (2) cryopreserved isograft (Group 2); (3) cryopreserved isograft with intraneural IGF-1 administration (Group 3). 12 weeks after surgery, functional recovery (Sciatic functional index [SFI], Swing speed [SS], nerve conduction velocity [NCV], amplitude of compound motor action potentials [CMAP], and gastrocnemius muscle index [GMI]) and nerve regeneration (myelin sheath area, total fiber counts, fiber density, and fiber width) were all evaluated.

RESULTS

The intraneural injection of IGF-1 significantly improved SFI and SS at weeks 10 and 12. There were no statistical differences between Groups 1 and 3 in any of the SFI or SS evaluations. CMAP and NCV in Group 1 were significantly higher than in Groups 2 and 3, and Group 3 had significantly higher CMAP and NCV compared to Group 2. No significant differences were found in fiber width. The number of nerve fibers, percentage of myelinated fibers, fiber density, and GMI was significantly higher in Group 1 compared to Group 2, but no significant differences were found between Groups 1 and 3.

CONCLUSION

The results show that intraneural injection of IGF-1 in an 18 mm cryopreserved isograft improve axonal regeneration and functional recovery.

Screening of NogoA/NTR-related differential genes in rat sciatic nerve injury signal pathway

AIM

To screen the differential genes in NogoA/NTR-related pathways that associate with sciatic nerve injury.

RESULTS

There was no difference in the expression of NogoA, NTR and Ntrk2. Differential genes existed in 11 differential pathways that include NogoA, NTR and Ntrk2. Pathways closely related to sciatic nerve injury are MAPK, endophagocytosis, apoptosis, neurotrophin signaling and inflammatory mediators. NTRK1, FASLG, LDLR ADRB1 and HTR2A in model rats were downregulated compared with control rats, IL1R1, CSF1R, BCL2L1 and HRH1 in model rats were upregulated compared with control rats.

CONCLUSION

MAPK, endophagocytic, apoptotic, neurotrophic factor and inflammatory mediators of ductal mediators may be involved in the sciatic nerve injury in rats. The differentially expressed genes in these pathways may play important roles in sciatic nerve injury.

Preparation of Messenger RNA Nanomicelles via Non-Cytotoxic PEG-Polyamine Nanocomplex for Intracerebroventicular Delivery: A Proof-of-Concept Study in Mouse Models

The specific delivery of messenger RNA (mRNA) is an excellent alternative to plasmid DNA, due to the latter’s potential risk for random integration into the host genome. In this study, we propose the use of specially tailored polyplex nanomicelles for the intravenous delivery of mRNA into the brain of mice. In brief, along the backbone of a polyaspartamide polymer that is terminated with a 42k Polyethylene glycol chain (PEG), aminoethylene-repeating groups (two, three, and four units, respectively) were conjugated to side-chains to promote electrostatic interactions with mRNA. This structural configuration would ultimately condense into a polyplex nanomicelle ranging between 24 and 34 nm, as was confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) while the chemistry of the synthesis was validated through NMR analysis. Subsequently, we hypothesized an important correlation pertaining to the role of hydrogen bonding between the interaction of polyamine and mRNA in due course. As a proof of concept, we encapsulated the luciferase (Luc2) mRNA as a reporter gene through in vitro transcription (IVT) and subsequently infused the polyplex nanomicelles into mouse brains via an intracerebroventricular (ICV) injection to bypass the blood–brain barriers (BBB). Data revealed that PEGylated polyplex nanomicelles possessing four repeating units of aminoethylene groups had exhibited the best Luc2 mRNA delivery efficiency with no significant immune response registered.

Gene therapy for the mitochondrial genome: Purging mutations, pacifying ailments

In the recent years, the reported cases of mitochondrial disorders have reached a colossal number. These disorders spawn a sundry of pathological conditions, which lead to pernicious symptoms and even fatality. Due to the unpredictable etiologies, mitochondrial diseases are putatively referred to as "mystondria" (mysterious diseases of mitochondria). Although present-day research has greatly improved our understanding of mitochondrial disorders, effective therapeutic interventions are still at the precursory stage. The conundrum becomes further complicated because these pathologies might occur due to either mitochondrial DNA (mtDNA) mutations or due to mutations in the nuclear DNA (nDNA), or both. While correcting nDNA mutations by using gene therapy (replacement of defective genes by delivering wild-type (WT) ones into the host cell, or silencing a dominant mutant allele that is pathogenic) has emerged as a promising strategy to address some mitochondrial diseases, the complications in correcting the defects of mtDNA in order to renovate mitochondrial functions have remained a steep challenge. In this review, we focus specifically on the selective gene therapy strategies that have demonstrated prospects in targeting the pathological mutations in the mitochondrial genome, thereby treating mitochondrial ailments.

Translational Advances of Hydrofection by Hydrodynamic Injection

Hydrodynamic gene delivery has proven to be a safe and efficient procedure for gene transfer, able to mediate, in murine model, therapeutic levels of proteins encoded by the transfected gene. In different disease models and targeting distinct organs, it has been demonstrated to revert the pathologic symptoms and signs. The therapeutic potential of hydrofection led different groups to work on the clinical translation of the procedure. In order to prevent the hemodynamic side effects derived from the rapid injection of a large volume, the conditions had to be moderated to make them compatible with its use in mid-size animal models such as rat, hamster and rabbit and large animals as dog, pig and primates. Despite the different approaches performed to adapt the conditions of gene delivery, the results obtained in any of these mid-size and large animals have been poorer than those obtained in murine model. Among these different strategies to reduce the volume employed, the most effective one has been to exclude the vasculature of the target organ and inject the solution directly. This procedure has permitted, by catheterization and surgical procedures in large animals, achieving protein expression levels in tissue close to those achieved in gold standard models. These promising results and the possibility of employing these strategies to transfer gene constructs able to edit genes, such as CRISPR, have renewed the clinical interest of this procedure of gene transfer. In order to translate the hydrodynamic gene delivery to human use, it is demanding the standardization of the procedure conditions and the molecular parameters of evaluation in order to be able to compare the results and establish a homogeneous manner of expressing the data obtained, as ‘classic’ drugs.

Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal mechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma (PRP) therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field. Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and (pre-)clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of injured peripheral nerves around dental implants is discussed.

Effects of Treatment of Treadmill Combined with Electro-Acupuncture on Tibia Bone Mass and Substance PExpression of Rabbits with Sciatic Nerve Injury

The peripheral nervous system may play an important role in normal bone maintenance and remodeling. Substance P (SP) is a neuropeptide associated with bone loss and formation that may mediate the effects of the nervous system. The purpose of this study is to determine if treadmill running combined with electro-acupuncture at Jiaji acupoints (Jiaji-EA) affects tibial bone mass and SP expression in rabbits with sciatic nerve injury. Twenty-four juvenile male New Zealand white rabbits were randomly assigned to one of 4 groups: sham injury control (sham), sciatic never crush control (SNCr), treadmill running (treadmill), and Jiaji-EA combined with treadmill running (ET group). The SNCr, treadmill, and ET groups all had an induced sciatic never crush injury of approximately 2mm. Control groups received no intervention; the treadmill and ET groups were trained by treadmill; the ET group also received Jiaji-EA. After the 4 weeks of treatment, toe-spreading index (TSI), BMD, bone strength, and SP expression in the tibia were significantly lower in the nerve injury groups (SNCr, treadmill, and ET) compared to the sham groups (p<0.05). Treatment (treadmill and ET groups) increased all measures compared to the SNCr group (p<0.05). Further, TSI, BMD, bone strength, and SP expression in the ET group were higher than the treadmill group (p<0.05). Our results indicate that treadmill therapy combined with electro-acupuncture at Jiaji acupoints prevents bone loss in rabbit tibias after sciatic nerve injury. This may occur in two ways: indirectly in association with axon regeneration and directly via loading on the bone mediated through increased SP expression. This study provides important evidence for the clinical treatment of bone loss after peripheral nerve injury.

A block copolymer containing PEG and histamine-like segments: well-defined functions for gene delivery

PEG-b-PAMPImB with well-defined functions, including high colloidal stability, effective DNA condensation and buffering capacity, self-assembles with pDNA for lower toxicity and higher efficient gene transfection.

Messenger RNA-based therapeutics for the treatment of apoptosis-associated diseases

Gene therapy is a promising approach for treating diseases that are closely associated with excessive apoptosis, because the gene can effectively and sustainably introduce anti-apoptotic factors into cells. However, DNA delivery poses the risk of random genomic integration, leading to overexpression of the delivered gene and cancer development. Messenger RNA (mRNA) can evade integration events in target cells. We examined the use of mRNA-based therapeutics for introducing anti-apoptotic factors by using a mouse model of fulminant hepatitis. For introducing mRNA into the liver, a synthesised polymer-based carrier of polyplex nanomicelles was used for hydrodynamic intravenous injection. Using GFP as a reporter, we demonstrate that mRNA delivery induced efficient protein expression in almost 100% of liver cells, while plasmid DNA (pDNA) delivery provided a smaller percentage of GFP-positive cells. Analyses using Cy5-labelled mRNA and pDNA revealed that efficient expression by mRNA was attributed to a simple intracellular mechanism, without the need for nuclear entry. Consistent with this observation, Bcl-2 mRNA was more effective on reducing apoptosis in the liver of mice with fulminant hepatitis than Bcl-2 pDNA. Therefore, mRNA-based therapeutics combined with an effective delivery system such as polyplex nanomicelles is a promising treatment for intractable diseases associated with excessive apoptosis.

The effects of different tensile parameters for the neurodynamic mobilization technique on tricipital muscle wet weight and MuRf-1 expression in rabbits with sciatic nerve injury

Background

After peripheral nerve injury, muscles without innervation begin to undergo atrophy. Research has suggested that MuRf-1 may play a role in muscle atrophy. The neurodynamic mobilization technique (NMT) is a manual therapy method used to elongate a nerve along its long axis, resulting in improved blood flow to the nerve. However, the nerve can be damaged if elongated too much. The purpose of this study is to observe the effect of NMT on muscle wet weight and MuRf-1 expression in rabbits with sciatic nerve injury.

Methods

Six adult rabbits were measured to determine the relationship between the joint angle of the lower limb and percent of sciatic nerve elongation to define the tensile parameters of NMT; Thirty adult rabbits were randomly assigned into a sham, model, NMT-A, NMT-B, or NMT-C groups. Four weeks post-treatment, the wet mass of the tricipital muscles and MuRf-1 expression were observed.

Results

The wet mass of the tricipital muscles in the NMT-B group was significantly greater than the NMT-A, NMT-C, and model groups. In addition, MuRf-1 expression was significantly reduced in the NMT-B group compared with the NMT-A, NMT-C, and model groups.

Conclusions

Elongating the nerve by NMT of 9% in rabbits decreased MuRf-1 expression and decelerated muscle atrophy in the subjects with sciatic nerve injury.

Peripheral nerve regeneration: experimental strategies and future perspectives

Peripheral nerve injuries represent a substantial clinical problem with insufficient or unsatisfactory treatment options. This review summarises all the events occurring after nerve damage at the level of the cell body, the site of injury and the target organ. Various experimental strategies to improve neuronal survival, axonal regeneration and target reinnervation are described including pharmacological approaches and cell-based therapies. Given the complexity of nerve regeneration, further studies are needed to address the biology of nerve injury, to improve the interaction with implantable scaffolds, and to implement cell-based therapies in nerve tissue engineering.