Genetically modified non-human primate models for research on neurodegenerative diseases

Neurodegenerative diseases(NDs)are a group of debilitating neurological disorders that primarily affect elderly populations and include Alzheimer's disease(AD),Parkinson's disease(PD),Huntington's disease(HD),and amyotrophic lateral sclerosis(ALS).Currently,there are no therapies available that can delay,stop,or reverse the pathological progression of NDs in clinical settings.As the population ages,NDs are imposing a huge burden on public health systems and affected families.Animal models are important tools for preclinical investigations to understand disease pathogenesis and test potential treatments.While numerous rodent models of NDs have been developed to enhance our understanding of disease mechanisms,the limited success of translating findings from animal models to clinical practice suggests that there is still a need to bridge this translation gap.Old World nonhuman primates(NHPs),such as rhesus,cynomolgus,and vervet monkeys,are phylogenetically,physiologically,biochemically,and behaviorally most relevant to humans.This is particularly evident in the similarity of the structure and function of their central nervous systems,rendering such species uniquely valuable for neuroscience research.Recently,the development of several genetically modified NHP models of NDs has successfully recapitulated key pathologies and revealed novel mechanisms.This review focuses on the efficacy of NHPs in modeling NDs and the novel pathological insights gained,as well as the challenges associated with the generation of such models and the complexities involved in their subsequent analysis.

Adenovirus-mediated human brain-derived neurotrophic factor gene-modified bone marrow mesenchymal stem cell transplantation for spinal cord injury

Rat bone marrow mesenchymal stem cells expressing brain-derived neurotrophic factor were successfully obtained using a gene transfection method, then intravenously transplanted into rats with spinal cord injury. At 1,3, and 5 weeks after transplantation, the expression of brain-derived neurotrophic factor and neurofilament-200 was upregulated in the injured spinal cord, spinal cord injury was alleviated, and Basso-Beattie-Bresnahan scores of hindlimb motor function were significantly increased. This evidence suggested that intravenous transplantation of adenovirus- mediated brain-derived neurotrophic factor gene-modified rat bone marrow mesenchymal stem cells could play a dual role, simultaneously providing neural stem cells and neurotrophic factors.

Regulating the fate of stem cells for regenerating the intervertebral disc degeneration

Lower back pain is a leading cause of disability and is one of the reasons for the substantial socioeconomic burden.The etiology of intervertebral disc(IVD)degeneration is complicated,and its mechanism is still not completely understood.Factors such as aging,systemic inflammation,biochemical mediators,toxic environmental factors,physical injuries,and genetic factors are involved in the progression of its pathophysiology.Currently,no therapy for restoring degenerated IVD is available except pain management,reduced physical activities,and surgical intervention.Therefore,it is imperative to establish regenerative medicine-based approaches to heal and repair the injured disc,repopulate the cell types to retain water content,synthesize extracellular matrix,and strengthen the disc to restore normal spine flexion.Cellular therapy has gained attention for IVD management as an alternative therapeutic option.In this review,we present an overview of the anatomical and molecular structure and the surrounding pathophysiology of the IVD.Modern therapeutic approaches,including proteins and growth factors,cellular and gene therapy,and cell fate regulators are reviewed.Similarly,small molecules that modulate the fate of stem cells for their differentiation into chondrocytes and notochordal cell types are highlighted.

In vitro study of micro-dystrophin gene-modified mesenchymal stem cells

BACKGROUND： Studies have shown that the transplantation of mesenchymal stem cells （MSCs） improves dystrophin expression in muscle cell membrane of mdx mice and plays a role in ameliorating sport injuries to the myocyte. In addition, dystrophin gene plasmid injection exhibits therapeutic effect in mdx mice. However, these two methods exhibit shortcomings, such as low rate of post-transplantation expression. Therefore, the present study determined the combinatorial effects of these two methods. OBJECTIVE： To transfect and observe effects of pSL139 plasmid carrying the micro-dystrophin gene into MSCs, as well as in vitro micro-dystrophin gene expression in transfected MSCs. DESIGN, TIME AND SETTING： A comparative, molecular biology study was performed at the Laboratory of Tissue Engineering, West China Medical Center, Sichuan University from March 2007 to February 2008. MATERIALS： The pSL139 plasmid was cloned and provided by the Department of Neurology, Washington University, USA. Lipofectamine 2000 was purchased from Invitrogen, USA. Mouse anti-human dystrophin N-based terminal monoclonal antibody was purchased from Chemicon, USA. METHODS： Differential velocity adherent technique and density gradient centrifugation were combined to separate and culture MSCs from C57/BL10 mice. The cells were induced to trans-differentiate into osteoblasts. Subsequently, the Lipofectamine 2000 method was used to mediate transfection of plasmid pSL139 into third generation MSCs. MAIN OUTCOME MEASURES： Semi-quantitative reverse transcription polymerase-chain reaction and immunofluorescence were respectively employed to detect micro-dystrophin mRNA and protein expressions in MSCs. RESULTS： At 48 hours after MSC transfection with plasmid pSL139, a 379-kb target band was observed by agarose gel electrophoresis. Immunofluorescence revealed micro-dystrophin expression up to 45%-55%. CONCLUSION： Micro-dystrophin mRNA and protein were highly expressed in pSL139-transfected MSCs, which provided a method for efficient expression of dystrophin.

Chronic wounds:pathological characteristics and their stem cell-based therapies

Chronic wounds are characterized by prolonged healing processes and poor prognoses,which have substantially impacted human health and daily life.Traditional treatment strategies have various limitations and drawbacks.Therefore,fully effective therapeutic approaches remain urgently needed.Stem cell(SC)-based therapies have drawn significant attention for their abilities of immunomodulation and pro-regeneration.It has been demon-strated that stem cells(SCs)can improve angiogenesis,collagen deposition,and hair rejuvenation,thus facilitating wound healing.In addition,attempts were performed to facilitate the cell survival,function,retention,and en-graftment of the delivered SCs.In this review,we first introduce the pathological process involved in chronic wound healing.Following that,the mechanism of SCs in promoting chronic wound repair is discussed in detail.Then,we highlight recent SC-based therapies for chronic wound repair developments.Finally,we present our views on the remaining challenges and future trends of SC-based therapies for chronic wound treatment.

Application of CRISPR/Cas9 in plant biology

The CRISPR/Cas(clustered regularly interspaced short palindromic repeats/CRISPRassociated proteins) system was first identified in bacteria and archaea and can degrade exogenous substrates. It was developed as a gene editing technology in 2013. Over the subsequent years, it has received extensive attention owing to its easy manipulation, high efficiency, and wide application in gene mutation and transcriptional regulation in mammals and plants. The process of CRISPR/Cas is optimized constantly and its application has also expanded dramatically. Therefore, CRISPR/Cas is considered a revolutionary technology in plant biology. Here, we introduce the mechanism of the type II CRISPR/Cas called CRISPR/Cas9, update its recent advances in various applications in plants, and discuss its future prospects to provide an argument for its use in the study of medicinal plants.

TALENs:Customizable Molecular DNA Scissors for Genome Engineering of Plants

Precise genome modification with engineered nucleases is a powerful tool for studying basic biology and applied biotechnology. Transcription activator-like effector nucleases（TALENs）,consisting of an engineered specific（TALE） DNA binding domain and a Fok I cleavage domain,are newly developed versatile reagents for genome engineering in different organisms.Because of the simplicity of the DNA recognition code and their modular assembly,TALENs can act as customizable molecular DNA scissors inducing double-strand breaks（DSBs） at given genomic location.Thus,they provide a valuable approach to targeted genome modifications such as mutations, insertions,replacements or chromosome rearrangements.In this article,we review the development of TALENs,and summarize the principles and tools for TALEN-mediated gene targeting in plant cells,as well as current and potential strategies for use in plant research and crop improvement.