CRISPR/Cas system: An emerging technology in stem cell research

Tissue Engineering and Regenerative Medicine: Perspectives and Challenges

From the pioneering days of cell therapy to the achievement of bioprinting organs, tissue engineering, and regenerative medicine have seen tremendous technological advancements, offering solutions for restoring damaged tissues and organs. However, only a few products and technologies have received United States Food and Drug Administration approval. This review highlights significant progress in cell therapy, extracellular vesicle-based therapy, and tissue engineering. Hematopoietic stem cell transplantation is a powerful tool for treating many diseases, especially hematological malignancies. Mesenchymal stem cells have been extensively studied. The discovery of induced pluripotent stem cells has revolutionized disease modeling and regenerative applications, paving the way for personalized medicine. Gene therapy represents an innovative approach to the treatment of genetic disorders. Additionally, extracellular vesicle-based therapies have emerged as rising stars, offering promising solutions in diagnostics, cell-free therapeutics, drug delivery, and targeted therapy. Advances in tissue engineering enable complex tissue constructs, further transforming the field. Despite these advancements, many technical, ethical, and regulatory challenges remain. This review addresses the current bottlenecks, emphasizing novel technologies and interdisciplinary research to overcome these hurdles. Standardizing practices and conducting clinical trials will balance innovation and regulation, improving patient outcomes and quality of life.

Bringing ophthalmology into the scientific world: Novel nanoparticle-based strategies for ocular drug delivery

The distinctive benefits and drawbacks of various drug delivery strategies to supply corneal tissue improvement for sense organs have been the attention of studies worldwide in recent decades. Static and dynamic barriers of ocular tissue prevent foreign chemicals from entering and inhibit the active absorption of therapeutic medicines. The distribution of different medications to ocular tissue is one of the most appealing and demanding tasks for investigators in pharmacology, biomaterials, and ophthalmology, and it is critical for cornea wound healing due to the controlled release rate and increased drug bioavailability. It should be mentioned that the transport of various types of medications into the different sections of the eye, particularly the cornea, is exceedingly challenging because of its distinctive structure and various barriers throughout the eye. Nanoparticles are being studied to improve medicine delivery strategies for ocular disease. Repetitive corneal drug delivery using biodegradable nanocarriers allows a medicine to remain in different parts of the cornea for extended periods of time and thus improve administration route effectiveness. In this review, we discussed eye anatomy, ocular delivery barriers, as well as the emphasis on the biodegradable nanomaterials ranging from organic nanostructures, such as nanomicelles, polymers, liposomes, niosomes, nanowafers, nanoemulsions, nanosuspensions, nanocrystals, cubosomes, olaminosomes, hybridized NPs, dendrimers, bilosomes, solid lipid NPs, nanostructured lipid carriers, and nanofiber to organic nanomaterials like silver, gold, and mesoporous silica nanoparticles. In addition, we describe the nanotechnology-based ophthalmic medications that are presently on the market or in clinical studies. Finally, drawing on current trends and therapeutic approaches, we discuss the challenges that innovative optical drug delivery systems confront and propose future research routes. We hope that this review will serve as a source of motivation and inspiration for developing innovative ophthalmic formulations.

Human pluripotent stem cell (hPSC)-derived models for autism spectrum disorder drug discovery

INTRODUCTION

Autism spectrum disorder (ASD) is a prevalent and complex neurodevelopmental disorder (NDD) with genetic and environmental origins. Currently, there are no effective pharmacological treatments targeting core ASD features. This leads to unmet medical needs of individuals with ASD and requires relevant human disease models recapitulating genetic and clinical heterogeneity to better understand underlying mechanisms and identify potential pharmacological therapies. Recent advancements in stem cell technology have enabled the generation of human pluripotent stem cell (hPSC)-derived two-dimensional (2D) and three-dimensional (3D) neural models, which serve as powerful tools for ASD modeling and drug discovery.

AREAS COVERED

This article reviews the applications of hPSC-derived 2D and 3D neural models in studying various forms of ASD using pharmacological perturbation and drug screenings, highlighting the potential use of these models to develop novel pharmacological treatment strategies for ASD.

EXPERT OPINION

hPSC-derived models recapitulate early human brain development spatiotemporally and have allowed patient-specific mechanistic investigation and therapeutic development using advanced molecular technologies, which will contribute to precision medicine for ASD therapy. Improvements are still required in hPSC-based models to further enhance their physiological relevance, clinical translation, and scalability for ASD drug discovery.

Standardization and consensus in the development and application of bone organoids

Organoids, self-organized structures derived from stem cells cultured in a specific three-dimensional (3D) in vitro microenvironment, have emerged as innovative platforms that closely mimic in vivo cellular behavior, tissue architecture, and organ function. Bone organoids, a frontier in organoid research, can replicate the complex structures and functional characteristics of bone tissue. Recent advancements have led to the successful development of bone organoids, including models of callus, woven bone, cartilage, trabecular bone, and bone marrow. These organoids are widely utilized in establishing bone-related disease models, bone injury repair, and drug screening. However, significant discrepancies remain between current bone organoids and human skeletal tissues in terms of morphology and functionality, limiting their ability to accurately model human bone physiology and pathology. To address these challenges and promote standardization in the construction, evaluation, and application of bone organoids, we have convened experts and research teams with substantial expertise in the field. By integrating existing research findings, this consortium aims to establish a consensus to guide future research and application of bone organoids.

Stem Cell Therapy for the Treatment of Amyotrophic Lateral Sclerosis: Comparison of the Efficacy of Mesenchymal Stem Cells, Neural Stem Cells, and Induced Pluripotent Stem Cells

BACKGROUND/OBJECTIVES

Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, is a debilitating, incurable neurodegenerative disorder characterised by motor neuron death in the spinal cord, brainstem, and motor cortex. With an incidence rate of about 4.42 cases per 100,000 people annually, ALS severely impacts motor function and quality of life, causing progressive muscle atrophy, spasticity, paralysis, and eventually death. The cause of ALS is largely unknown, with 90% of cases being sporadic and 10% familial. Current research targets molecular mechanisms of inflammation, excitotoxicity, aggregation-prone proteins, and proteinopathy.

METHODS

This review evaluates the efficacy of three stem cell types in ALS treatment: mesenchymal stem cells (MSCs), neural stem cells (NSCs), and induced pluripotent stem cells (iPSCs).

RESULTS

MSCs, derived from various tissues, show neuroprotective and regenerative qualities, with clinical trials suggesting potential benefits but limited by small sample sizes and non-randomised designs. NSCs, isolated from the fetal spinal cord or brain, demonstrate promise in animal models but face functional integration and ethical challenges. iPSCs, created by reprogramming patient-specific somatic cells, offer a novel approach by potentially replacing or supporting neurons. iPSC therapy addresses ethical issues related to embryonic stem cells but encounters challenges regarding genotoxicity and epigenetic irregularities, somatic cell sources, privacy concerns, the need for extensive clinical trials, and high reprogramming costs.

CONCLUSIONS

This research is significant for advancing ALS treatment beyond symptomatic relief and modest survival extensions to actively modifying disease progression and improving patient outcomes. Successful stem cell therapies could lead to new ALS treatments, slowing motor function loss and reducing symptom severity.

Revolutionizing medicine: recent developments and future prospects in stem-cell therapy

Stem-cell therapy is a revolutionary frontier in modern medicine, offering enormous capacity to transform the treatment landscape of numerous debilitating illnesses and injuries. This review examines the revolutionary frontier of treatments utilizing stem cells, highlighting the distinctive abilities of stem cells to undergo regeneration and specialized cell differentiation into a wide variety of phenotypes. This paper aims to guide researchers, physicians, and stakeholders through the intricate terrain of stem-cell therapy, examining the processes, applications, and challenges inherent in utilizing stem cells across diverse medical disciplines. The historical journey from foundational contributions in the late 19th and early 20th centuries to recent breakthroughs, including ESC isolation and iPSC discovery, has set the stage for monumental leaps in medical science. Stem cells' regenerative potential spans embryonic, adult, induced pluripotent, and perinatal stages, offering unprecedented therapeutic opportunities in cancer, neurodegenerative disorders, cardiovascular ailments, spinal cord injuries, diabetes, and tissue damage. However, difficulties, such as immunological rejection, tumorigenesis, and precise manipulation of stem-cell behavior, necessitate comprehensive exploration and innovative solutions. This manuscript summarizes recent biotechnological advancements, critical trial evaluations, and emerging technologies, providing a nuanced understanding of the triumphs, difficulties, and future trajectories in stem cell-based regenerative medicine. Future directions, including precision medicine integration, immune modulation strategies, advancements in gene-editing technologies, and bioengineering synergy, offer a roadmap in stem cell treatment. The focus on stem-cell therapy's potential highlights its significant influence on contemporary medicine and points to a future in which individualized regenerative therapies will alleviate various medical disorders.

Optimizing CRISPR/Cas9 precision: Mitigating off-target effects for safe integration with photodynamic and stem cell therapies in cancer treatment

CRISPR/Cas9 precision genome editing has revolutionized cancer treatment by introducing specific alterations to the cancer genome. But the therapeutic potential of CRISPR/Cas9 is limited by off-target effects, which can cause undesired changes to genomic regions and create major safety concerns. The primary emphasis lies in their implications within the realm of cancer photodynamic therapy (PDT), where precision is paramount. PDT is a promising cancer treatment method; nevertheless, its effectiveness is severely limited and readily leads to recurrence due to the therapeutic resistance of cancer stem cells (CSCs). With a focus on targeted genome editing into cancer cells during PDT and stem cell treatment (SCT), the review aims to further the ongoing search for safer and more accurate CRISPR/Cas9-mediated methods. At the core of this exploration are recent advancements and novel techniques that offer promise in mitigating the risks associated with off-target effects. With a focus on cancer PDT and SCT, this review critically assesses the landscape of off-target effects in CRISPR/Cas9 applications, offering a comprehensive knowledge of their nature and prevalence. A key component of the review is the assessment of cutting-edge delivery methods, such as technologies based on nanoparticles (NPs), to optimize the distribution of CRISPR components. Additionally, the study delves into the intricacies of guide RNA design, focusing on advancements that bolster specificity and minimize off-target effects, crucial elements in ensuring the precision required for effective cancer PDT and SCT. By synthesizing insights from various methodologies, including the exploration of innovative genome editing tools and leveraging robust validation methods and bioinformatics tools, the review aspires to chart a course towards more reliable and precise CRISPR-Cas9 applications in cancer PDT and SCT. For safe PDT and SCT integration in cancer therapy, CRISPR/Cas9 precision optimization is essential. Utilizing sophisticated molecular and computational techniques to address off-target effects is crucial to realizing the therapeutic promise of these technologies, which will ultimately lead to the development of individualized and successful cancer treatment strategies. Our long-term goals are to improve precision genome editing for more potent cancer therapy approaches by refining the way CRISPR/Cas9 is integrated with photodynamic and stem cell therapies.

Regenerative rehabilitation: a novel multidisciplinary field to maximize patient outcomes

Regenerative rehabilitation is a novel and rapidly developing multidisciplinary field that converges regenerative medicine and rehabilitation science, aiming to maximize the functions of disabled patients and their independence. While regenerative medicine provides state-of-the-art technologies that shed light on difficult-to-treated diseases, regenerative rehabilitation offers rehabilitation interventions to improve the positive effects of regenerative medicine. However, regenerative scientists and rehabilitation professionals focus on their aspects without enough exposure to advances in each other's field. This disconnect has impeded the development of this field. Therefore, this review first introduces cutting-edge technologies such as stem cell technology, tissue engineering, biomaterial science, gene editing, and computer sciences that promote the progress pace of regenerative medicine, followed by a summary of preclinical studies and examples of clinical investigations that integrate rehabilitative methodologies into regenerative medicine. Then, challenges in this field are discussed, and possible solutions are provided for future directions. We aim to provide a platform for regenerative and rehabilitative professionals and clinicians in other areas to better understand the progress of regenerative rehabilitation, thus contributing to the clinical translation and management of innovative and reliable therapies.

Pancreatic stellate cells support human pancreatic β-cell viability in vitro and enhance survival of immunoisolated human islets exposed to cytokines

Pancreatic islet transplantation is proposed as a cure for type 1 diabetes mellitus (T1D). Despite its success in optimal regulation of glucose levels, limitations in longevity of islet grafts still require innovative solutions. Inflammatory stress post-transplantation and loss of extracellular matrix attribute to the limited β-cell survival. Pancreatic stellate cells (PSCs), identified as pancreatic-specific stromal cells, have the potential to play a crucial role in preserving islet survival. Our study aimed to determine the effects of PSCs co-cultured with human CM β-cells and human islets under inflammatory stress induced by a cytokine cocktail of IFN-γ, TNF-α and IL-1β. Transwell culture inserts were utilized to assess the paracrine impact of PSCs on β-cells, alongside co-cultures enabling direct interaction between PSCs and human islets. We found that co-culturing PSCs with human CM β-cells and human cadaveric islets had rescuing effects on cytokine-induced stress. Effects were different under normoglycemic and hyperglycemic conditions. PSCs were associated with upregulation of β-cell mitochondrial activity and suppression of inflammatory gene expression. The rescuing effects exist both in indirect and direct co-culture methods. Furthermore, we tested whether PSCs have rescuing effects on human islets in conventional alginate-based microcapsules and in composite microcapsules composed of alginate-pectin collagen type IV, laminin sequence RGD, Nec-1, and amino acid. PSCs partially prevented cytokine-induced stress in both systems, but beneficial effects were stronger in composite capsules. Our findings show novel effects of PSCs on islet health. Islets and PSCs coculturing or co-transplantation might mitigate the inflammation stress and improve islet transplantation outcomes.

Current strategies using 3D organoids to establish in vitro maternal-embryonic interaction

IMPORTANCE

The creation of robust maternal-embryonic interactions and implantation models is important for comprehending the early stages of embryonic development and reproductive disorders. Traditional two-dimensional (2D) cell culture systems often fail to accurately mimic the highly complex in vivo conditions. The employment of three-dimensional (3D) organoids has emerged as a promising strategy to overcome these limitations in recent years. The advancements in the field of organoid technology have opened new avenues for studying the physiology and diseases affecting female reproductive tract.

OBSERVATIONS

This review summarizes the current strategies and advancements in the field of 3D organoids to establish maternal-embryonic interaction and implantation models for use in research and personalized medicine in assisted reproductive technology. The concepts of endometrial organoids, menstrual blood flow organoids, placental trophoblast organoids, stem cell-derived blastoids, and in vitro-generated embryo models are discussed in detail. We show the incorportaion of organoid systems and microfluidic technology to enhance tissue performance and precise management of the cellular surroundings.

CONCLUSIONS AND RELEVANCE

This review provides insights into the future direction of modeling maternal-embryonic interaction research and its combination with other powerful technologies to interfere with this dialogue either by promoting or hindering it for improving fertility or methods for contraception, respectively. The merging of organoid systems with microfluidics facilitates the creation of sophisticated and functional organoid models, enhancing insights into organ development, disease mechanisms, and personalized medical investigations.

dCas9 Tells Tales: Probing Gene Function and Transcription Regulation in Cancer

Clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing is evolving into an essential tool in the field of biological and medical research. Notably, the development of catalytically deactivated Cas9 (dCas9) enzyme has substantially broadened its traditional boundaries in gene editing or perturbation. The conjugation of dCas9 with various molecular effectors allows precise control over transcriptional processes, epigenetic modifications, visualization of chromosomal dynamics, and several other applications. This expanded repertoire of CRISPR-Cas9 applications has emerged as an invaluable molecular tool kit that empowers researchers to comprehensively interrogate and gain insights into health and diseases. This review delves into the advancements in Cas9 protein engineering, specifically on the generation of various dCas9 tools that have significantly enhanced the CRISPR-based technology capability and versatility. We subsequently discuss the multifaceted applications of dCas9, especially in interrogating the regulation and function of genes that involve in supporting cancer pathogenesis. In addition, we also delineate the designing and utilization of dCas9-based tools as well as highlighting its current constraints and transformative potentials in cancer research.

Engineering a CRISPRoff Platform to Modulate Expression of Myeloid Cell Leukemia (MCL-1) in Committed Oligodendrocyte Neural Precursor Cells

In vitro differentiation of human pluripotent stem cell (hPSC) model systems has furthered our understanding of human development. Techniques used to elucidate gene function during early development have encountered technical challenges, especially when targeting embryonic lethal genes. The introduction of CRISPRoff by Nuñez and collaborators provides an opportunity to heritably silence genes during long-term differentiation. We modified CRISPRoff and sgRNA Sleeping Beauty transposon vectors that depend on tetracycline-controlled transcriptional activation to silence the expression of embryonic lethal genes at different stages of differentiation in a stable manner. We provide instructions on how to generate sgRNA transposon vectors that can be used in combination with our CRISPRoff transposon vector and a stable hPSC line. We validate the use of this tool by silencing MCL-1, an anti-apoptotic protein, which results in pre-implantation embryonic lethality in mice; this protein is necessary for oligodendrocyte and hematopoietic stem cell development and is required for the in vitro survival of hPSCs. In this protocol, we use an adapted version of the differentiation protocol published by Douvaras and Fossati (2015) to generate oligodendrocyte lineage cells from human embryonic stem cells (hESCs). After introduction of the CRISPRoff and sgRNAs transposon vectors in hESCs, we silence MCL-1 in committed oligodendrocyte neural precursor cells and describe methods to measure its expression. With the methods described here, users can design sgRNA transposon vectors targeting MCL-1 or other essential genes of interest to study human oligodendrocyte development or other differentiation protocols that use hPSC model systems. Key features • Generation of an inducible CRISPRoff Sleeping Beauty transposon system. • Experiments performed in vitro for generation of inducible CRISPRoff pluripotent stem cell line amenable to oligodendrocyte differentiation. • Strategy to downregulate an essential gene at different stages of oligodendrocyte development.

Induced Pluripotent Stem Cells in the Era of Precise Genome Editing

Genome editing has enhanced our ability to understand the role of genetics in a number of diseases by facilitating the development of more precise cellular and animal models to study pathophysiological processes. These advances have shown extraordinary promise in a multitude of areas, from basic research to applied bioengineering and biomedical research. Induced pluripotent stem cells (iPSCs) are known for their high replicative capacity and are excellent targets for genetic manipulation as they can be clonally expanded from a single cell without compromising their pluripotency. Clustered, regularly interspaced short palindromic repeats (CRISPR) and CRISPR/Cas RNA-guided nucleases have rapidly become the method of choice for gene editing due to their high specificity, simplicity, low cost, and versatility. Coupling the cellular versatility of iPSCs differentiation with CRISPR/Cas9-mediated genome editing technology can be an effective experimental technique for providing new insights into the therapeutic use of this technology. However, before using these techniques for gene therapy, their therapeutic safety and efficacy following models need to be assessed. In this review, we cover the remarkable progress that has been made in the use of genome editing tools in iPSCs, their applications in disease research and gene therapy as well as the hurdles that remain in the actual implementation of CRISPR/Cas systems.

An Insight into the Prospects and Drawbacks of Stem Cell Therapy for Spinal Cord Injuries: Ongoing Trials and Future Directions

Spinal cord injury (SCI) is a devastating neurological disorder that has a substantial detrimental impact on a person's quality of life. The estimated global incidence of SCI is 40 to 80 cases per million people and around 90% of cases are traumatic. Various etiologies can be recognized for SCI, and post-traumatic SCI represents the most common of these. Patients worldwide with SCI suffer from a persistent loss of motor and sensory function, which affects every aspect of their personal and social lives. Given the lack of effective treatments, many efforts have been made to seek a cure for this condition. In recent years, thanks to their ability to regenerate tissue and repair lost or damaged cells, much attention has been directed toward the use of stem cells (embryonic, induced pluripotent, mesenchymal, hematopoietic), aimed at restoring the functional integrity of the damaged spinal cord and improving a functional recovery including sensory and motor function. In this paper, we offer an overview of the benefits and drawbacks of stem cell therapy for SCI based on clinical evidence. This report also addresses the characteristics of various stem cell treatments, as well as the field's likely future. Each cell type targets specific pathological characteristics associated with SCI and demonstrates therapeutic effects via cell replacement, nutritional support, scaffolds, and immunomodulation pathways. SCI accompanied by complex pathological processes cannot be resolved by single treatment measures. Stem cells are associated with the adjustment of the expression of neurotrophic factors that help to achieve better nutrition to damaged tissue. Single-cell treatments have been shown in some studies to provide very minor benefits for SCI in multiple preclinical studies and a growing number of clinical trials. However, SCI damage is complex, and many studies are increasingly recognizing a combination approach such as physical therapy, electrical stimulation, or medication therapy to treatment.

Biomaterials-mediated CRISPR/Cas9 delivery: recent challenges and opportunities in gene therapy

The use of biomaterials in delivering CRISPR/Cas9 for gene therapy in infectious diseases holds tremendous potential. This innovative approach combines the advantages of CRISPR/Cas9 with the protective properties of biomaterials, enabling accurate and efficient gene editing while enhancing safety. Biomaterials play a vital role in shielding CRISPR/Cas9 components, such as lipid nanoparticles or viral vectors, from immunological processes and degradation, extending their effectiveness. By utilizing the flexibility of biomaterials, tailored systems can be designed to address specific genetic diseases, paving the way for personalized therapeutics. Furthermore, this delivery method offers promising avenues in combating viral illnesses by precisely modifying pathogen genomes, and reducing their pathogenicity. Biomaterials facilitate site-specific gene modifications, ensuring effective delivery to infected cells while minimizing off-target effects. However, challenges remain, including optimizing delivery efficiency, reducing off-target effects, ensuring long-term safety, and establishing scalable production techniques. Thorough research, pre-clinical investigations, and rigorous safety evaluations are imperative for successful translation from the laboratory to clinical applications. In this review, we discussed how CRISPR/Cas9 delivery using biomaterials revolutionizes gene therapy and infectious disease treatment, offering precise and safe editing capabilities with the potential to significantly improve human health and quality of life.

RNA-Dependent RNA Targeting by CRISPR-Cas Systems: Characterizations and Applications

Genome editing technologies that are currently available and described have a fundamental impact on the development of molecular biology and medicine, industrial and agricultural biotechnology and other fields. However, genome editing based on detection and manipulation of the targeted RNA is a promising alternative to control the gene expression at the spatiotemporal transcriptomic level without complete elimination. The innovative CRISPR-Cas RNA-targeting systems changed the conception of biosensing systems and also allowed the RNA effectors to be used in various applications; for example, genomic editing, effective virus diagnostic tools, biomarkers, transcription regulations. In this review, we discussed the current state-of-the-art of specific CRISPR-Cas systems known to bind and cleave RNA substrates and summarized potential applications of the versatile RNA-targeting systems.

Research and Therapeutic Approaches in Stem Cell Genome Editing by CRISPR Toolkit

The most widely used genome editing toolkit is CRISPR (clustered regularly interspaced short palindromic repeats). It provides the possibility of replacing and modifying DNA and RNA nucleotides. Furthermore, with advancements in biological technology, inhibition and activation of the transcription of specific gene(s) has become possible. Bioinformatics tools that target the evolution of CRISPR-associated protein 9 (Cas9) turn this protein into a vehicle that is specific for a DNA or RNA region with single guide RNA (sgRNA). This toolkit could be used by researchers to investigate the function of stem cell gene(s). Here, in this review article, we cover recent developments and applications of this technique in stem cells for research and clinical purposes and discuss different CRISPR/Cas technologies for knock-out, knock-in, activation, or inhibition of gene expression. Additionally, a comparison of several deliveries and off-target detecting strategies is discussed.

Induced pluripotent stem cells from domesticated ruminants and their potential for enhancing livestock production

Ruminant livestock, including cattle, sheep, goat, and buffalo, are essential for global food security and serve valuable roles in sustainable agricultural systems. With the limited availability of embryonic stem cells (ESCs) from these species, ruminant induced pluripotent stem cells (iPSCs) and iPSC-like cells provide a valuable research tool for agricultural, veterinary, biomedical, and pharmaceutical applications, as well as for the prospect of translation to human medicine. iPSCs are generated by reprogramming of adult or fetal cells to an ESC-like state by ectopic expression of defined transcription factors. Despite the slow pace the field has evolved in livestock species compared to mice and humans, significant progress has been made over the past 15 years in using different cell sources and reprogramming protocols to generate iPSCs/iPSC-like cells from ruminants. This mini review summarizes the current literature related to the derivation of iPSCs/iPSC-like cells from domesticated ruminants with a focus on reprogramming protocols, characterization, associated limitations, and potential applications in ruminant basic science research and production.

Iron Oxide Nanoparticles in Mesenchymal Stem Cell Detection and Therapy

Mesenchymal stem cells (MSCs) exhibit regenerative and reparative properties. However, most MSC-related studies remain to be translated for regular clinical usage, partly due to challenges in pre-transplantation cell labelling and post-transplantation cell tracking. Amidst this, there are growing concerns over the toxicity of commonly used gadolinium-based contrast agents that mediate in-vivo cell detection via MRI. This urges to search for equally effective but less toxic alternatives that would facilitate and enhance MSC detection post-administration and provide therapeutic benefits in-vivo. MSCs labelled with iron oxide nanoparticles (IONPs) have shown promising results in-vitro and in-vivo. Thus, it would be useful to revisit these studies before inventing new labelling approaches. Aiming to inform regenerative medicine and augment clinical applications of IONP-labelled MSCs, this review collates and critically evaluates the utility of IONPs in enhancing MSC detection and therapeutics. It explains the rationale, principle, and advantages of labelling MSCs with IONPs, and describes IONP-induced intracellular alterations and consequent cellular manifestations. By exemplifying clinical pathologies, it examines contextual in-vitro, animal, and clinical studies that used IONP-labelled bone marrow-, umbilical cord-, adipose tissue- and dental pulp-derived MSCs. It compiles and discusses studies involving MSC-labelling of IONPs in combinations with carbohydrates (Venofer, ferumoxytol, dextran, glucosamine), non-carbohydrate polymers [poly(L-lysine), poly(lactide-co-glycolide), poly(L-lactide), polydopamine], elements (ruthenium, selenium, gold, zinc), compounds/stains (silica, polyethylene glycol, fluorophore, rhodamine B, DAPI, Prussian blue), DNA, Fibroblast growth Factor-2 and the drug doxorubicin. Furthermore, IONP-labelling of MSC exosomes is reviewed. Also, limitations of IONP-labelling are addressed and methods of tackling those challenges are suggested.

Therapeutic Strategies for Mutant SPAST-Based Hereditary Spastic Paraplegia

Mutations of the SPAST gene that encodes the microtubule-severing enzyme called spastin are the chief cause of Hereditary Spastic Paraplegia. Growing evidence indicates that pathogenic mutations functionally compromise the spastin protein and endow it with toxic gain-of-function properties. With each of these two factors potentially relevant to disease etiology, the present article discusses possible therapeutic strategies that may ameliorate symptoms in patients suffering from SPAST-based Hereditary Spastic Paraplegia, which is usually termed SPG4-HSP.

Modelling Mitochondrial Disease in Human Pluripotent Stem Cells: What Have We Learned?

Mitochondrial diseases disrupt cellular energy production and are among the most complex group of inherited genetic disorders. Affecting approximately 1 in 5000 live births, they are both clinically and genetically heterogeneous, and can be highly tissue specific, but most often affect cell types with high energy demands in the brain, heart, and kidneys. There are currently no clinically validated treatment options available, despite several agents showing therapeutic promise. However, modelling these disorders is challenging as many non-human models of mitochondrial disease do not completely recapitulate human phenotypes for known disease genes. Additionally, access to disease-relevant cell or tissue types from patients is often limited. To overcome these difficulties, many groups have turned to human pluripotent stem cells (hPSCs) to model mitochondrial disease for both nuclear-DNA (nDNA) and mitochondrial-DNA (mtDNA) contexts. Leveraging the capacity of hPSCs to differentiate into clinically relevant cell types, these models permit both detailed investigation of cellular pathomechanisms and validation of promising treatment options. Here we catalogue hPSC models of mitochondrial disease that have been generated to date, summarise approaches and key outcomes of phenotypic profiling using these models, and discuss key criteria to guide future investigations using hPSC models of mitochondrial disease.

CRISPR/Cas9 in epigenetics studies of health and disease

Epigenetics is the heritable phenotypic changes without altering the genotype. Epigenetic processes are such as histone methylation, acetylation, ubiquitination, sumoylation, phosphorylation, ADP ribosylation, DNA methylation and non-coding RNAs interactions associated with structural changes in chromatin. The change of structure is either open chromatin for "active" state or closed chromatin for "inactive" state, that regulates important biological phenomenon like chromatin condensation, gene expression, DNA repair, cellular development, differentiation and homeostasis, etc. However, dysregulation of epigenetic patterns causes diseases like cancer, diabetes, neurological disorder, infectious diseases, autoimmunity etc. Besides, the most important clinical uses of Epigenetics studies are i. identification of disease biomarkers and ii. development of their therapeutics. Epigenetic therapies include epi-drugs, combinatorial therapy, nanocarriers, plant-derived products that are being used for changing the epigenetic pattern to reverse gene expression. However, the developed epi- drugs cause off-target gene and transposable elements activation; promote mutagenesis and carcinogenesis in normal cells, are the major hurdles regarding their clinical use. Therefore, advanced epigenetic therapeutics are required to develop target-specific epigenetic modifications to reverse gene expression pattern. CRISPR-Cas9 (Clustered Regularly Interspaced Palindrome Repeats-associated protein 9) system-mediated gene activation mechanism paves new methods of target-specific epigenetic therapeutics to cure diseases. In this chapter, we discuss how CRISPR/Cas9 and dCas9 have recently been engineered for epigenome editing. Different strategies have been discussed used for epigenome editing based on their efficacy and complexity. Last but not least we have discussed the limitations, different uses of CRISPR/Cas9 and dCas9 in the area of genetic engineering.

A Review of Current Strategies Towards the Elimination of Latent HIV-1 and Subsequent HIV-1 Cure

Background

During the past 35 years, highly effective ART has saved the lives of millions of people worldwide by suppressing viruses to undetectable levels. However, this does not translate to the absence of viruses in the body as HIV persists in latent reservoirs. Indeed, rebounded HIV has been recently observed in the Mississippi and California infants previously thought to have been cured. Hence, much remains to be learned about HIV latency, and the search for the best strategy to eliminate the reservoir is the direction current research is taking. A systems-level approach that fully recapitulates the dynamics and complexity of HIV-1 latency In vivo and is applicable in human therapy is prudent for HIV eradication to be more feasible.

Objectives

The main barriers preventing the cure of HIV with antiretroviral therapy have been identified, progress has been made in the understanding of the therapeutic targets to which potentially eradicating drugs could be directed, integrative strategies have been proposed, and clinical trials with various alternatives are underway. The aim of this review is to provide an update on the main advances in HIV eradication, with particular emphasis on the obstacles and the different strategies proposed. The core challenges of each strategy are highlighted and the most promising strategy and new research avenues in HIV eradication strategies are proposed.

Methods

A systematic literature search of all English-language articles published between 2015 and 2019, was conducted using MEDLINE (PubMed) and Google scholar. Where available, medical subject headings (MeSH) were used as search terms and included: HIV, HIV latency, HIV reservoir, latency reactivation, and HIV cure. Additional search terms consisted of suppression, persistence, establishment, generation, and formation. A total of 250 articles were found using the above search terms. Out of these, 89 relevant articles related to HIV-1 latency establishment and eradication strategies were collected and reviewed, with no limitation of study design. Additional studies (commonly referenced and/or older and more recent articles of significance) were selected from bibliographies and references listed in the primary resources.

Results

In general, when exploring the literature, there are four main strategies heavily researched that provide promising strategies to the elimination of latent HIV: Haematopoietic Stem-Cell Transplantation, Shock and Kill Strategy, Gene-specific transcriptional activation using RNA-guided CRISPR-Cas9 system, and Block and Lock strategy. Most of the studies of these strategies are applicable in vitro, leaving many questions about the extent to which, or if any, these strategies are applicable to complex picture In vivo. However, the success of these strategies at least shows, in part, that HIV-1 can be cured, though some strategies are too invasive and expensive to become a standard of care for all HIV-infected patients.

Conclusion

Recent advances hold promise for the ultimate cure of HIV infection. A systems-level approach that fully recapitulates the dynamics and complexity of HIV-1 latency In vivo and applicable in human therapy is prudent for HIV eradication to be more feasible. Future studies aimed at achieving a prolonged HIV remission state are more likely to be successful if they focus on a combination strategy, including the block and kill, and stem cell approaches. These strategies propose a functional cure with minimal toxicity for patients. It is believed that the cure of HIV infection will be attained in the short term if a strategy based on purging the reservoirs is complemented with an aggressive HAART strategy.

Evaluation of multiple gene targeting in porcine embryos by the CRISPR/Cas9 system using electroporation

The CRISPR/Cas9 system now allows for unprecedented possibilities of genome editing. However, there are some limitations, including achieving efficient one-step multiple genome targeting to save costs, time, and ensure high quality. In the present study, we investigated the efficiency of one-step multiple gene modification by electroporation in porcine zygotes using pooled guide RNAs (gRNAs) targeting CMAH, GHR, GGTA1, and PDX1. We first selected the best-performing gRNA from three different designs for each gene based on the effect on embryo development and mutation efficiency. The three gRNAs showed equivalent effects on the rates of blastocyst formation in each targeted gene; however, gRNAs CMAH #2, GHR #3, GGTA1 #3, and PDX1 #3 showed the highest biallelic mutation rate, although the total mutation rate of PDX1 #3 was significantly lower than that of PDX1 #1. Therefore, CMAH #2, GHR #3, GGTA1 #3, and PDX1 #1 were used as a mixture in electroporation to further clarify whether multiple genes can be targeted simultaneously. Individual sequencing of 43 blastocysts at the target sites of each gene showed mutations in one and two target genes in twenty-four (55.8%) and nine (20.9%) blastocysts, respectively. No mutation was detected in any target gene in ten (23.3%) blastocysts and no blastocysts had a mutation in three or more target genes. These results indicate that electroporation could effectively deliver multiple gRNAs and Cas9 protein into porcine zygotes to target multiple genes in a one-step process. However, the technique requires further development to increase the success rate of multiple gene modification.

RNA-Targeting CRISPR-Cas Systems and Their Applications

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-associated (Cas) systems have revolutionized modern molecular biology. Numerous types of these systems have been discovered to date. Many CRISPR-Cas systems have been used as a backbone for the development of potent research tools, with Cas9 being the most widespread. While most of the utilized systems are DNA-targeting, recently more and more attention is being gained by those that target RNA. Their ability to specifically recognize a given RNA sequence in an easily programmable way makes them ideal candidates for developing new research tools. In this review we summarize current knowledge on CRISPR-Cas systems which have been shown to target RNA molecules, that is type III (Csm/Cmr), type VI (Cas13), and type II (Cas9). We also present a list of available technologies based on these systems.