MicroRNA-regulated viral vectors for gene therapy

Safe and effective gene therapy approaches require targeted tissue-specific transfer of a therapeutic transgene.Besides traditional approaches, such as transcriptional and transductional targeting, micro RNA-dependent posttranscriptional suppression of transgene expression has been emerging as powerful new technology to increase the specificity of vector-mediated transgene expression. Micro RNAs are small non-coding RNAs and often expressed in a tissue-, lineage-, activation- or differentiation-specific pattern. They typically regulate gene expression by binding to imperfectly complementary sequences in the 3' untranslated region(UTR) of the m RNA. To control exogenous transgene expression, tandem repeats of artificial micro RNA target sites are usually incorporated into the 3' UTR of the transgene expression cassette, leading to subsequent degradation of transgene m RNA in cel s expressing the corresponding micro RNA. This targeting strategy, first shown for lentiviral vectors in antigen presenting cells, has now been used for tissue-specific expression of vector-encoded therapeutic transgenes, to reduce immune response against the transgene, to control virus tropism for oncolytic virotherapy, to increase safety of live attenuated virus vaccines and to identify and select cell subsets for pluripotent stem cell therapies, respectively. This review provides an introduction into the technical mechanism underlying micro RNA-regulation, highlights new developments in this field and gives an overview of applications of micro RNA-regulated viral vectors for cardiac, suicide gene cancer and hematopoietic stem cell therapy, as well as for treatment of neurological and eye diseases.

A new can didate vaccine for human brucellosis based on influenza viral vectors:a preliminary investigation for the development of an immunization schedule in a guinea pig model

Background:A new candidate vector vaccine against human brucellosis based on recombinant influenza viral vectors(rIVV)subtypes H5N1 expressing Brucella outer membrane protein(Omp)16,L7/L12,Omp19or Cu-Zn SOD proteins has been developed.This paper presents the results of the study of protection of the vaccine using on guinea pigs,including various options of administering,dose and frequency.Provided data of the novel vaccine candidate will contribute to its further movement into the preclinical stage study.Methods:General states of guinea pigs was assessed based on behavior and dynamics of a guinea pig weight-gain test.The effectiveness of the new anti-brucellosis vector vaccine was determined by studying its protective effect after conjunctival,intranasal and sublingual administration in doses 10^(5) EID50,10^(6) EID_(50) and 10^(7) EID_(50) during prime and boost vaccinations of animals,followed by challenge with a virulent strain of B.melitensis 16 M infection.For sake of comparison,the commercial ft melitensis Rev.1 vaccine was used as a control.The protective properties of vaccines were assessed by quantitation of Brucella colonization in organs and tissues of infected animals and compared to the control groups.Results:It was observed a gradual increase in body weight of guinea pigs after prime and booster immunization with the vacci ne using conjunctival,intra nasal and subli ngual routes of administration,as well as after using various doses of vaccine.The most optimal way of using the vaccine has been established:double intranasal immunization of guinea pigs at a dose of 10^(6) EID50, which provides 80%protection of guinea pigs from B.melitensis 16 M infection(P<0.05),which is comparable to the results of the effectiv en ess of the commercial B.melitensis Rev.1 vacci ne.Conclusions:We developed effective human vaccine candidate against brucellosis and developed its immunization protocol in guinea pig model.We believe that because of these studies,the proposed vaccine has achieved the best level of protection,which in turn provides a basis for its further promotion.

Increasingβ-hexosaminidase A activity using genetically modified mesenchymal stem cells

GM2 gangliosidoses are a group of autosomal-recessive lysosomal storage disorde rs.These diseases result from a deficiency of lysosomal enzymeβ-hexosaminidase A(HexA),which is responsible for GM2 ganglioside degradation.HexA deficiency causes the accumulation of GM2-gangliosides mainly in the nervous system cells,leading to severe progressive neurodegeneration and neuroinflammation.To date,there is no treatment for these diseases.Cell-mediated gene therapy is considered a promising treatment for GM2 gangliosidoses.This study aimed to evaluate the ability of genetically modified mesenchymal stem cells(MSCs-HEXA-HEXB)to restore HexA deficiency in Tay-Sachs disease patient cells,as well as to analyze the functionality and biodistribution of MSCs in vivo.The effectiveness of HexA deficiency cross-correction was shown in mutant MSCs upon intera ction with MSCs-HEXA-HEXB.The results also showed that the MSCs-HEXA-HEXB express the functionally active HexA enzyme,detectable in vivo,and intravenous injection of the cells does not cause an immune response in animals.These data suggest that genetically modified mesenchymal stem cells have the potentials to treat GM2 gangliosidoses.

A Viral Expression Vector from Foxtail mosaic virus to Express Green Fluorescent Protein

[Objective]Foxtail mosaic virus(FoMV)infects gramineous and dicotyledonous plants.In this study,we sought to construct a viral vector based on FoMV to express exogenous proteins in plants.[Method]A recombinant viral expression vector was constructed by inserting the promotor of Potato virus X(PVX)and exogenous gene sequences into the 3’non-coding region of the FoMV coat protein gene.[Results]The plasmid pCB301-FoMV-CP-PVXprom-GFP expressed green fluorescent protein in inoculated Nicotiana benthamiana leaves.[Conclusion]A recombinant viral expression vector was constructed successfully.

The potential of gene therapies for spinal cord injury repair:a systematic review and meta-analysis of pre-clinical studies

Currently,there is no cure for traumatic spinal co rd injury but one therapeutic approach showing promise is gene therapy.In this systematic review and meta-analysis,we aim to assess the efficacy of gene therapies in pre-clinical models of spinal cord injury and the risk of bias.In this metaanalysis,registe red at PROSPERO(Registration ID:CRD42020185008),we identified relevant controlled in vivo studies published in English by searching the PubMed,Web of Science,and Embase databases.No restrictions of the year of publication were applied and the last literature search was conducted on August 3,2020.We then conducted a random-effects meta-analysis using the restricted maximum likelihood estimator.A total of 71 studies met our inclusion crite ria and were included in the systematic review.Our results showed that overall,gene therapies were associated with improvements in locomotor score(standardized mean difference[SMD]:2.07,95%confidence interval[CI]:1.68-2.47,Tau^(2)=2.13,I^(2)=83.6%)and axonal regrowth(SMD:2.78,95%CI:1.92-3.65,Tau^(2)=4.13,I^(2)=85.5%).There was significant asymmetry in the funnel plots of both outcome measures indicating the presence of publication bias.We used a modified CAMARADES(Collaborative Approach to M eta-Analysis and Review of Animal Data in Experimental Studies)checklist to assess the risk of bias,finding that the median score was 4(IQR:3-5).In particula r,reports of allocation concealment and sample size calculations were lacking.In conclusion,gene therapies are showing promise as therapies for spinal co rd injury repair,but there is no consensus on which gene or genes should be targeted.

Viral-mediated gene therapy in pediatric neurological disorders

Background Due to the broad application of next-generation sequencing,the molecular diagnosis of genetic disorders in pediatric neurology is no longer an unachievable goal.However,treatments for neurological genetic disorders in children remain primarily symptomatic.On the other hand,with the continuous evolution of therapeutic viral vectors,gene therapy is becoming a clinical reality.From this perspective,we wrote this review to illustrate the current state regarding viral-mediated gene therapy in childhood neurological disorders.Data sources We searched databases,including PubMed and Google Scholar,using the keywords"adenovirus vector,""lentivirus vector,"and"AAv"for gene therapy,and"immunoreaction induced by gene therapy vectors,""administration routes of gene therapy vectors,"and"gene therapy"with"NCL,""SMA,""DMD,""congenital myopathy,""MPS""leukodystrophy,"or"pediatric metabolic disorders".We also screened the database of ClinicalTrials.gov using the keywords"gene therapy for children"and then filtered the results with the ones aimed at neurological disorders.The time range of the search procedure was from the inception of the databases to the present.Results We presented the characteristics of commonly used viral vectors for gene therapy for pediatric neurological disorders and summarized their merits and drawbacks,the administration routes of each vector,the research progress,and the clinical application status of viral-mediated gene therapy on pediatric neurological disorders.Conclusions Viral-mediated gene therapy is on the brink of broad clinical application.Viral-mediated gene therapy will dramatically change the treatment pattern of childhood neurological disorders,and many children with incurable diseases will meet the dawn of a cure.Nevertheless,the vectors must be optimized for better safety and efficacy.

CRISPR/Cas9 systems:Delivery technologies and biomedical applications

The emergence of the clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)genome-editing system has brought about a significant revolution in the realm of managing human diseases,establishing animal models,and so on.To fully harness the potential of this potent gene-editing tool,ensuring efficient and secure delivery to the target site is paramount.Consequently,developing effective delivery methods for the CRISPR/Cas9 system has become a critical area of research.In this review,we present a comprehensive outline of delivery strategies and discuss their biomedical applications in the CRISPR/Cas9 system.We also provide an indepth analysis of physical,viral vector,and non-viral vector delivery strategies,including plasmid-,mRNA-and protein-based approach.In addition,we illustrate the biomedical applications of the CRISPR/Cas9 system.This review highlights the key factors affecting the delivery process and the current challenges facing the CRISPR/Cas9 system,while also delineating future directions and prospects that could inspire innovative delivery strategies.This review aims to provide new insights and ideas for advancing CRISPR/Cas9-based delivery strategies and to facilitate breakthroughs in biomedical research and therapeutic applications.

Applications and developments of gene therapy drug delivery systems for genetic diseases

Genetic diseases seriously threaten human health and have always been one of the refractory conditions facing humanity.Currently,gene therapy drugs such as siRNA,shRNA,antisense oligonucleotide,CRISPR/Cas9 system,plasmid DNA and miRNA have shown great potential in biomedical applications.To avoid the degradation of gene therapy drugs in the body and effectively deliver them to target tissues,cells and organelles,the development of excellent drug delivery vehicles is of utmost importance.Viral vectors are the most widely used delivery vehicles for gene therapy in vivo and in vitro due to their high transfection efficiency and stable transgene expression.With the development of nanotechnology,novel nanocarriers are gradually replacing viral vectors,emerging superior performance.This review mainly illuminates the current widely used gene therapy drugs,summarizes the viral vectors and non-viral vectors that deliver gene therapy drugs,and sums up the application of gene therapy to treat genetic diseases.Additionally,the challenges and opportunities of the field are discussed from the perspective of developing an effective nano-delivery system.

Small interfering RNAs based therapies for intracerebral hemorrhage: challenges and progress in drug delivery systems

Intracerebral hemorrhage(ICH)is a subtype of stroke associated with higher rates of mortality.Currently,no effective drug treatment is available for ICH.The molecular pathways following ICH are complicated and diverse.Nucleic acid therapeutics such as gene knockdown by small interfering RNAs(siRNAs)have been developed in recent years to modulate ICH’s destructive pathways and mitigate its outcomes.However,siRNAs delivery to the central nervous system is challenging and faces many roadblocks.Existing barriers to systemic delivery of siRNA limit the use of naked siRNA;therefore,siRNA-vectors developed to protect and deliver these therapies into the specific-target areas of the brain,or cell types seem quite promising.Efficient delivery of siRNA via nanoparticles emerged as a viable and effective alternative therapeutic tool for central nervous system-related diseases.This review discusses the obstacles to siRNA delivery,including the advantages and disadvantages of viral and nonviral vectors.Additionally,we provide a comprehensive overview of recent progress in nanotherapeutics areas,primarily focusing on the delivery system of siRNA for ICH treatment.

New therapeutic opportunities for Hepatitis C based on small RNA

Hepatitis C virus （HCV） infection is one of the major causes of chronic liver disease, including cirrhosis and liver cancer and is therefore, the most common indication for liver transplantation. Conventional antiviral drugs such as pegylated interferon-alpha, taken in combination with ribavirin, represent a milestone in the therapy of this disease. However, due to different viral and host factors, clinical success can be achieved only in approximately half of patients, making urgent the requirement of exploiting alternative approaches for HCV therapy. Fortunately, recent advances in the understanding of HCV viral replication and host cell interactions have opened new possibilities for therapeutic intervention. The most recent technologies, such as small interference RNA mediated gene-silencing, antisense oligonucleotides （ASO）, or viral vector based gene delivery systems, have paved the way to develop novel therapeutic modalities for HCV. In this review, we outline the application of these technologies in the context of HCV therapy. In particular, we will focus on the newly defined role of cellular microRNA （miR-222） in viral replication and discuss its potential for HCV molecular therapy.

Room for improvement in the treatment of pancreatic cancer: Novel opportunities from gene targeted therapy

Pancreatic cancer is one of the highest and in fact,unchanged mortality-associated tumor,with an exceptionally low survival rate due to its challenging diagnostic approach.So far,its treatment is based on a combination of approaches(such as surgical resection with or rarely without chemotherapeutic agents),but with finite limits.Thus,looking for additional space to improve pancreatic tumorigenesis therapeutic approach,research has focused on gene therapy with unexpectedly growing horizons not only for the treatment of inoperable pancreatic disease,but also for its early stages.In vivo gene delivery viral vectors,despite few disadvantages(possible immunogenicity,toxicity,mutagenicity,or high cost),could be one of the most efficient cancer gene therapeutic strategies for clinical application due to their superiority compared with other systems(ex vivo delivery strategies).Their dominance consists of simple preparation,easy operation and a wide range of functions.Adenoviruses are one of the most common used vectors,inducing strong immune as well as inflammatory reactions.Oncolytic virotherapy,using the above mentioned in vivo viral vectors,is one of the most promising nonpathogenic,highly-selective cytotoxic anti-cancer therapy using anti-cancer agents with high anti-tumor potency and strong oncolytic effect.There have been a variety of targeted therapeutic and pre-clinical strategies tested for gene therapy in pancreatic cancer such as gene-editing systems(e.g.,clustered regularly interspaced palindromic repeats-Cas9),RNA interference technology(e.g.,microRNAs,short hairpin RNA or small interfering RNA),adoptive immunotherapy and vaccination(e.g.,chimeric antigen receptor T-cell therapy)with encouraging results.

Restoring axonal localization and transport of transmembrane receptors to promote repair within the injured CNS: a critical step in CNS regeneration

Each neuronal subtype is distinct in how it develops,responds to environmental cues,and whether it is capable of mounting a regenerative response following injury.Although the adult central nervous system（CNS） does not regenerate,several experimental interventions have been trialled with successful albeit limited instances of axonal repair.We highlight here some of these approaches including extracellular matrix（ECM） modification,cellular grafting,gene therapy-induced replacement of proteins,as well as application of biomaterials.We also review the recent report demonstrating the failure of axonal localization and transport of growth-promoting receptors within certain classes of mature neurons.More specifically,we discuss an inability of integrin receptors to localize within the axonal compartment of mature motor neurons such as in the corticospinal and rubrospinal tracts,whereas in immature neurons of those pathways and in mature sensory tracts such as in the optic nerve and dorsal column pathways these receptors readily localize within axons.Furthermore we assert that this failure of axonal localization contributes to the intrinsic inability of axonal regeneration.We conclude by highlighting the necessity for both combined therapies as well as a targeted approach specific to both age and neuronal subtype will be required to induce substantial CNS repair.

Inner ear hair cell regeneration A look from the past to the future

Most recent studies on regeneration of inner ear hair cells focus on use of stem cells, gene therapy and neurotrophic factors. Cochlear gene therapy has been successfully used in the treatment of neu- rosensory hearing loss. This suggests that cochlear hair cell regeneration is possible. The objective of this paper is to review research and clinical application of inner near hair cell regeneration.

Clinical applications of the CRISPR/Cas9 genome-editing system: Delivery options and challenges in precision medicine

CRISPR/Cas9 is an effective gene editing tool with broad applications for the pre-vention or treatment of numerous diseases.It depends on CRiSPR(clustered regularly inter-spaced short palindromic repeats)as a bacterial immune system and plays as a gene editing tool.Due to the higher specificity and efficiency of CRISPR/Cas9 compared to other editing ap-proaches,it has been broadly investigated to treat numerous hereditary and acquired ill-nesses,including cancers,hemolytic diseases,immunodeficiency disorders,cardiovascular diseases,visual maladies,neurodegenerative conditions,and a few X-linked disorders.CRISPR/Cas9 system has been used to treat cancers through a variety of approaches,with sta-ble gene editing techniques.Here,the applications and clinical trials of CRisPR/Cas9 in various illnesses are described.Due to its high precision and efficiency,CRISPR/Cas9 strategies may treat gene-related illnesses by deleting,inserting,modifying,or blocking the expression of specific genes.The most challenging barrier to the in vivo use of CRISPR/Cas9 like off-target effects will be discussed.The use of transfection vehicles for CRISPR/Cas9,including viral vectors(such as an Adeno-associated virus(AAV),and the development of non-viral vectors is also considered.

When mRNA meets gene editing

The critical challenge of gene therapy lies in delivering gene editing agents.Compared with DNA,while RNA is less stable and more accessible to degrade,it comes with the benefit of lower off-target effects since permanent insertion is not involved.This review focuses on mRNA-based delivery of gene editing agents,highlighting novel mRNA delivery systems.To provide context,a comparison is made between three main gene editing agents:programmable nucleases,base editors,and prime editors.The potential of Cas\pi and transposons is also discussed in this review.Additionally,a summary of four main barriers to mRNAbased in vivo delivery is provided.Furthermore,this review detailedly introduced different delivery systems,both viral(lentivirus)and non-viral vectors(genome editing via oviductal nucleic acids delivery,lipid nanoparticles,polymer-based nanoparticles,viruslike-particles,extracellular vesicles,and migrasome).Each delivery strategy is assessed by comparing its advantages and disadvantages to offer a comprehensive and objective overview of the delivery system.Moreover,we emphasized the vital role of the protein corona as a critical regulator for nanodelivery.Ultimately,we concluded the challenges of mRNA-based gene editing strategies(RNA stability,targeting,potential immunogenicity,cytotoxicity,heterogeneity,and rational design).The purpose of this review is to guide further research and provide a comprehensive analysis of mRNA-based in vivo delivery of gene editing agents in this promising field.

Gene therapy for hemophilia B mediated by recombinant adeno-associated viral vector with hFIXR338A,a high catalytic activity mutation of human coagulation factor IX

A mutant human factor IX with arginine at 338 residual changed to alanine (hFIXR338A) by site-directed mutagenesis was introduced into AAV vectors, and a recombinant adeno-associ-ated viral vector containing hFIXR338A, prepared by rHSV/AAV hybrid helper virus system, was directly introduced to the hind leg muscle of factor IX knock out mice. The expression and the biological activity of human factor IX mutant, hFIXR338A, and the immune response against it in the treated mice were assayed and detected. The results showed that (i) the high-level expression of human factor IX mutant protein, hFIXR338A, has been detected in rAAV-hFIXR338A treated hemophilia B mice and lasted more than 15 weeks; (ii) the clotting activity of hFIXR338A in plasma is 34.2%± 5.23%, which is remarkably higher than that of (14.27%±3.4%) of wild type hFIX treated mice in the activated partial thromboplastin assay; (iii) immune response against factor IX R338A was absent, with no factor IX mutant protein (hFIXR338A) inhibitors development in the treated mice; and (iv) no local or systemic side-effects and toxicity associated with the gene transfer were found. It demonstrated the potential use of treating hemophilia B by recombinant adeho-associated viral vectors with mutant hFIXR338A gene, an alternative strategy for hemophilia B gene therapy to wild-type human factor IX.

Tailoring minimalist self-assembling peptides for localized viral vector aene deliverv

Viral vector gene delivery is a promising technique for the therapeutic administra- tion of proteins to damaged tissue for the improvement of regeneration outcomes in various disease settings including brain and spinal cord injury, as well as autoimmune diseases. Though promising results have been demonstrated, limitations of viral vectors, including spread of the virus to distant sites, neutralization by the host immune system, and low transduction efficiencies have stimulated the investigation of biomaterials as gene delivery vehicles for improved protein expression at an injury site. Here, we show how N- fluorenylmethyloxycarbonyl （Fmoc） self-assembling peptide （SAP） hydrogels, designed for tissue-specific central nervous system （CNS） applications via incorporation of the laminin peptide sequence isoleucine-lysine-valine-alanine- valine （IKVAV）, are effective as biocompatible, localized viral vector gene delivery vehicles in vivo. Through the addition of a C-terminal lysine （K） residue, we show that increased electrostatic interactions, provided by the additional amine side chain, allow effective immobilization of lentiviral vector particles, thereby limiting their activity exclusively to the site of injection and enabling focal gene delivery in vivo in a tissue-specific manner. When the C-terminal lysine was absent, no difference was observed between the number of transfected cells, the volume of tissue transfected, or the transfection efficiency with and without the Fmoc-SAP. Importantly, immobilization of the virus only affected transfection cell number and volume, with no impact observed on transfection efficiency. This hydrogel allows the sustained and targeted delivery of growth factors post injury. We have established Fmoc-SAPs as a versatile platform for enhanced biomaterial design for a range of tissue engineering applications.

Non-viral and viral delivery systems for CRISPR-Cas9 technology in the biomedical field

The clustered regularly interspaced short palindromic repeats(CRISPR)-associated protein 9(CRISPR-Cas9) system provides a novel genome editing technology that can precisely target a genomic site to disrupt or repair a specific gene. Some CRISPR-Cas9 systems from different bacteria or artificial variants have been discovered or constructed by biologists, and Cas9 nucleases and single guide RNAs(sgRNA) are the major components of the CRISPR-Cas9 system. These Cas9 systems have been extensively applied for identifying therapeutic targets, identifying gene functions, generating animal models, and developing gene therapies.Moreover, CRISPR-Cas9 systems have been used to partially or completely alleviate disease symptoms by mutating or correcting related genes. However, the efficient transfer of CRISPR-Cas9 system into cells and target organs remains a challenge that affects the robust and precise genome editing activity. The current review focuses on delivery systems for Cas9 mRNA, Cas9 protein, or vectors encoding the Cas9 gene and corresponding sgRNA. Non-viral delivery of Cas9 appears to help Cas9 maintain its on-target effect and reduce off-target effects, and viral vectors for sgRNA and donor template can improve the efficacy of genome editing and homology-directed repair. Safe, efficient, and producible delivery systems will promote the application of CRISPR-Cas9 technology in human gene therapy.

Preparation of a recombinant adeno-associated viral vector with a mutation of human factor-Ⅸin large scale and its expression in vitro and in vivo

A series of adeno-associated viral vectors containing a mutation of human factor Ⅸ (hFⅨR338A) with different regulation elements were constructed and used to transduce cell lines. The plasmids and the stable transduction cell clones with high expression level of hFⅨR338A were obtained by selecting and optimizing, and then, the recombinant adeno-associated viral vector with hFⅨR338A was prepared via novel rHSV/AAV hybrid virus packaging system on a large scale, which contained the capsid protein genes. A method for producing rAAV-hFⅨR338A viral stocks on a large scale and higher titer was established, which can be used for industrial purpose. The titer of rAAV-hFⅨR338A was more than 1.25?012 particle/mL, and then, a mammalian cell line, C2C12 and the factor Ⅸ knock-out mice were transfected with the rAAV-hFⅨR338A in vitroand in vivo. The results show that the high-level expression of rAAV-hFⅨR338A was achieved in cell line and hemophilia B mice. It reached at (2551.32±92.14) ng·(106 cells)-1·(24h)-1 in C2C12 cell in vitro and had a peak concentration of 463.28 ng/mL in mice treated with rAAV-hFⅨR338A, which was as high as the expression of rAAV-hFⅨ-wt(2565.76?4.36) ng·(106 cells) -1·(24 h)-1 in C2C12 and453.92 ng/mL in the mice treated with rAAV-hFⅨ-wt) in vitro and in vivo, there is no any difference between two groups, but the clotting activity of hFⅨR338A is about 2.46 times higher than that of hFⅨ-wt. It was first reported that a mutation of human factor Ⅸ was used into gene therapyresearch for hemophilia B, meanwhile, a novel packagingsystem, rAAV/HSV was used for preparation of rAAV-hFⅨR338A on a large scale, which laid the foundation ofindustrial production for applying rAAV viral stocks to gene therapy clinical trial for hemophilia B mediated withrAAV-hFⅨ.

MSC based gene delivery methods and strategies improve the therapeutic efficacy of neurological diseases

Mesenchymal stem cells(MSCs)are promising seed cells for neural regeneration therapy owing to their plasticity and accessibility.They possess several inherent characteristics advantageous for the transplantation-based treatment of neurological disorders,including neural differentiation,immunosuppression,neurotrophy,and safety.However,the therapeutic efficacy of MSCs alone remains unsatisfactory in most cases.To improve some of their abilities,many studies have employed genetic engineering to transfer key genes into MSCs.Both viral and nonviral methods can be used to overexpress therapeutic proteins that complement the inherent properties.However,to date,different modes of gene transfer have specific drawbacks and advantages.In addition,MSCs can be functionalized through targeted gene modification to facilitate neural repair by promoting neural differentiation,enhancing neurotrophic and neuroprotective functions,and increasing survival and homing abilities.The methods of gene transfer and selection of delivered genes still need to be optimized for improved therapeutic and targeting efficacies while minimizing the loss of MSC function.In this review,we focus on gene transport technologies for engineering MSCs and the application of strategies for selecting optimal delivery genes.Further,we describe the prospects and challenges of their application in animal models of different neurological lesions to broaden treatment alternatives for neurological diseases.