A Broad Overview and Review of CRISPR-Cas Technology and Stem Cells

A bioinformatic approach to identify confirmed and probable CRISPR-Cas systems in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex genomes

Introduction

The Acinetobacter calcoaceticus-Acinetobacter baumannii complex, or Acb complex, consists of six species: Acinetobacter baumannii, Acinetobacter calcoaceticus, Acinetobacter nosocomialis, Acinetobacter pittii, Acinetobacter seifertii, and Acinetobacter lactucae. A. baumannii is the most clinically significant of these species and is frequently related to healthcare-associated infections (HCAIs). Clustered regularly interspaced short palindromic repeat (CRISPR) arrays and associated genes (cas) constitute bacterial adaptive immune systems and function as variable genetic elements. This study aimed to conduct a genomic analysis of Acb complex genomes available in databases to describe and characterize CRISPR systems and cas genes.

Methods

Acb complex genomes available in the NCBI and BV-BRC databases, the identification and characterization of CRISPR-Cas systems were performed using CRISPRCasFinder, CRISPRminer, and CRISPRDetect. Sequence types (STs) were determined using the Oxford scheme and ribosomal multilocus sequence typing (rMLST). Prophages were identified using PHASTER and Prophage Hunter.

Results

A total of 293 genomes representing six Acb species exhibited CRISPR-related sequences. These genomes originate from various sources, including clinical specimens, animals, medical devices, and environmental samples. Sequence typing identified 145 ribosomal multilocus sequence types (rSTs). CRISPR-Cas systems were confirmed in 26.3% of the genomes, classified as subtypes I-Fa, I-Fb and I-Fv. Probable CRISPR arrays and cas genes associated with CRISPR-Cas subtypes III-A, I-B, and III-B were also detected. Some of the CRISPR-Cas systems are associated with genomic regions related to Cap4 proteins, and toxin-antitoxin systems. Moreover, prophage sequences were prevalent in 68.9% of the genomes. Analysis revealed a connection between these prophages and CRISPR-Cas systems, indicating an ongoing arms race between the bacteria and their bacteriophages. Furthermore, proteins associated with anti-CRISPR systems, such as AcrF11 and AcrF7, were identified in the A. baumannii and A. pittii genomes.

Discussion

This study elucidates CRISPR-Cas systems and defense mechanisms within the Acb complex, highlighting their diverse distribution and interactions with prophages and other genetic elements. This study also provides valuable insights into the evolution and adaptation of these microorganisms in various environments and clinical settings.

Liver-directed gene therapy for inherited metabolic diseases

Gene therapy clinical trials are rapidly expanding for inherited metabolic liver diseases whilst two gene therapy products have now been approved for liver based monogenic disorders. Liver-directed gene therapy has recently become an option for treatment of haemophilias and is likely to become one of the favoured therapeutic strategies for inherited metabolic liver diseases in the near future. In this review, we present the different gene therapy vectors and strategies for liver-targeting, including gene editing. We highlight the current development of viral and nonviral gene therapy for a number of inherited metabolic liver diseases including urea cycle defects, organic acidaemias, Crigler-Najjar disease, Wilson disease, glycogen storage disease Type Ia, phenylketonuria and maple syrup urine disease. We describe the main limitations and open questions for further gene therapy development: immunogenicity, inflammatory response, genotoxicity, gene therapy administration in a fibrotic liver. The follow-up of a constantly growing number of gene therapy treated patients allows better understanding of its benefits and limitations and provides strategies to design safer and more efficacious treatments. Undoubtedly, liver-targeting gene therapy offers a promising avenue for innovative therapies with an unprecedented potential to address the unmet needs of patients suffering from inherited metabolic diseases.

The Potential of CRISPR/Cas Technology to Enhance Crop Performance on Adverse Soil Conditions

Worldwide food security is under threat in the actual scenery of global climate change because the major staple food crops are not adapted to hostile climatic and soil conditions. Significant efforts have been performed to maintain the actual yield of crops, using traditional breeding and innovative molecular techniques to assist them. However, additional strategies are necessary to achieve the future food demand. Clustered regularly interspaced short palindromic repeat/CRISPR-associated protein (CRISPR/Cas) technology, as well as its variants, have emerged as alternatives to transgenic plant breeding. This novelty has helped to accelerate the necessary modifications in major crops to confront the impact of abiotic stress on agriculture systems. This review summarizes the current advances in CRISPR/Cas applications in crops to deal with the main hostile soil conditions, such as drought, flooding and waterlogging, salinity, heavy metals, and nutrient deficiencies. In addition, the potential of extremophytes as a reservoir of new molecular mechanisms for abiotic stress tolerance, as well as their orthologue identification and edition in crops, is shown. Moreover, the future challenges and prospects related to CRISPR/Cas technology issues, legal regulations, and customer acceptance will be discussed.

Bilirubin-Induced Neurological Damage: Current and Emerging iPSC-Derived Brain Organoid Models

Bilirubin-induced neurological damage (BIND) has been a subject of studies for decades, yet the molecular mechanisms at the core of this damage remain largely unknown. Throughout the years, many in vivo chronic bilirubin encephalopathy models, such as the Gunn rat and transgenic mice, have further elucidated the molecular basis of bilirubin neurotoxicity as well as the correlations between high levels of unconjugated bilirubin (UCB) and brain damage. Regardless of being invaluable, these models cannot accurately recapitulate the human brain and liver system; therefore, establishing a physiologically recapitulating in vitro model has become a prerequisite to unveil the breadth of complexities that accompany the detrimental effects of UCB on the liver and developing human brain. Stem-cell-derived 3D brain organoid models offer a promising platform as they bear more resemblance to the human brain system compared to existing models. This review provides an explicit picture of the current state of the art, advancements, and challenges faced by the various models as well as the possibilities of using stem-cell-derived 3D organoids as an efficient tool to be included in research, drug screening, and therapeutic strategies for future clinical applications.

Onasemnogene abeparvovec for the treatment of spinal muscular atrophy

INTRODUCTION

Gene therapy for spinal muscular atrophy (SMA) represents a significant milestone in the treatment of neurologic diseases. SMA is a neurodegenerative disease that results in motor neuron loss because of mutations of the survival motor neuron 1 gene, which directs survival motor neuron (SMN) protein production. Onasemnogene abeparvovec, a one-time gene replacement therapy, delivers a functional transgene to restore SMN protein expression. Onasemnogene abeparvovec has demonstrated improved survival and motor milestone achievements for presymptomatic infants and patients with SMA type 1.

AREAS COVERED

This expert review describes the current state of gene therapy for SMA, reviews the mechanism of and clinical experience with onasemnogene abeparvovec, explains future efforts to expand applications of gene therapy for SMA, and provides context for developing gene therapy for other conditions.

EXPERT OPINION

Onasemnogene abeparvovec has demonstrated efficacy in clinical trials and, because of this, is a valuable treatment option for patients with symptomatic infantile SMA and those identified by newborn screening. Gene therapy is still in its infancy, and challenges and uncertainties associated with transgene delivery must be addressed. With ongoing development of vector technology, more specific tissue tropism, reduced "off-target" effects, and an enhanced safety profile will continue to evolve.

Coronavirus Disease 2019 (COVID-19) Diagnostic Tools: A Focus on Detection Technologies and Limitations

The ongoing coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a severe threat to human health and the global economy and has resulted in overwhelming stress on health care systems worldwide. Despite the global health catastrophe, especially in the number of infections and fatalities, the COVID-19 pandemic has also revolutionized research and discovery with remarkable success in diagnostics, treatments, and vaccine development. The use of many diagnostic methods has helped establish public health guidelines to mitigate the spread of COVID-19. However, limited information has been shared about these methods, and there is a need for the scientific community to learn about these technologies, in addition to their sensitivity, specificity, and limitations. This review article is focused on providing insights into the major methods used for SARS-CoV-2 detection. We describe in detail the core principle of each method, including molecular and serological approaches, along with reported claims about the rates of false negatives and false positives, the types of specimens needed, and the level of technology and the time required to perform each test. Although this study will not rank or prioritize these methods, the information will help in the development of guidelines and diagnostic protocols in clinical settings and reference laboratories.

Microfluidics in Biotechnology: Quo Vadis

The emerging technique of microfluidics offers new approaches for precisely controlling fluidic conditions on a small scale, while simultaneously facilitating data collection in both high-throughput and quantitative manners. As such, the so-called lab-on-a-chip (LOC) systems have the potential to revolutionize the field of biotechnology. But what needs to happen in order to truly integrate them into routine biotechnological applications? In this chapter, some of the most promising applications of microfluidic technology within the field of biotechnology are surveyed, and a few strategies for overcoming current challenges posed by microfluidic LOC systems are examined. In addition, we also discuss the intensifying trend (across all biotechnology fields) of using point-of-use applications which is being facilitated by new technological achievements.

Emulating Human Tissues and Organs: A Bioprinting Perspective Toward Personalized Medicine

The lack of in vitro tissue and organ models capable of mimicking human physiology severely hinders the development and clinical translation of therapies and drugs with higher in vivo efficacy. Bioprinting allow us to fill this gap and generate 3D tissue analogues with complex functional and structural organization through the precise spatial positioning of multiple materials and cells. In this review, we report the latest developments in terms of bioprinting technologies for the manufacturing of cellular constructs with particular emphasis on material extrusion, jetting, and vat photopolymerization. We then describe the different base polymers employed in the formulation of bioinks for bioprinting and examine the strategies used to tailor their properties according to both processability and tissue maturation requirements. By relating function to organization in human development, we examine the potential of pluripotent stem cells in the context of bioprinting toward a new generation of tissue models for personalized medicine. We also highlight the most relevant attempts to engineer artificial models for the study of human organogenesis, disease, and drug screening. Finally, we discuss the most pressing challenges, opportunities, and future prospects in the field of bioprinting for tissue engineering (TE) and regenerative medicine (RM).

The effects of CRISPR-Cas9 knockout of the TGF-β1 gene on antler cartilage cells in vitro

BACKGROUND

Deer antler is the only mammalian organ that can be completely regenerated every year. Its periodic regeneration is regulated by multiple factors, including transforming growth factor β (TGF-β). This widely distributed multi-functional growth factor can control the proliferation and differentiation of many types of cell, and it may play a crucial regulatory role in antler regeneration. This study explored the role of TGF-β1 during the rapid growth of sika deer antler.

METHODS

Three CRISPR-Cas9 knockout vectors targeting the TGF-β1 gene of sika deer were constructed and packaged with a lentiviral system. The expression level of TGF-β1 protein in the knockout cell line was determined using western blot, the proliferation and migration of cartilage cells in vitro were respectively determined using EdU and the cell scratch test, and the expression levels of TGF-β pathway-related genes were determined using a PCR array.

RESULTS

Of the three gRNAs designed, pBOBI-gRNA2 had the best knockout effect. Knockout of TGF-β1 gene inhibits the proliferation of cartilage cells and enhances their migration in vitro. TGF-β signaling pathway-related genes undergo significant changes, so we speculate that when the TGF-β pathway is blocked, the BMP signaling pathway mediated by BMP4 may play a key role.

CONCLUSIONS

TGF-β1 is a newly identified regulatory factor of rapid growth in sika deer antler.

Are we ready for genome editing in human embryos for clinical purposes?

Perhaps the two most significant pioneering biomedical discoveries with immediate clinical implications during the past forty years have been the advent of assisted reproductive technologies (ART) and the genetics revolution. ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection and preimplantation genetic testing, has resulted in the birth of more than 8 million children, and the pioneer of IVF, Professor Bob Edwards, was awarded the 2010 Nobel Prize. The genetics revolution has resulted in our genomes being sequenced and many of the molecular mechanisms understood, and technologies for genomic editing have been developed. With the combination of nearly routine ART protocols for healthy conceptions together with almost error-free, inexpensive and simple methods for genetic modification, the question "Are we ready for genome editing in human embryos for clinical purposes?" was debated at the 5th congress on controversies in preconception, preimplantation and Prenatal Genetic Diagnosis, in collaboration with the Ovarian Club Meeting, in November 2018 in Paris. The co-authors each presented scientific, medical and bioethical backgrounds, and the debate was chaired by Professor Alan Handyside. In this paper, we consider whether genome editing is safe and ethical. We conclude that we are currently not ready for genome editing to be used in human embryos for clinical purposes, and we call for a global debate to determine if and when this technology could be used in ART. ‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬.

The ethics of genome editing in non-human animals: a systematic review of reasons reported in the academic literature

In recent years, new genome editing technologies have emerged that can edit the genome of non-human animals with progressively increasing efficiency. Despite ongoing academic debate about the ethical implications of these technologies, no comprehensive overview of this debate exists. To address this gap in the literature, we conducted a systematic review of the reasons reported in the academic literature for and against the development and use of genome editing technologies in animals. Most included articles were written by academics from the biomedical or animal sciences. The reported reasons related to seven themes: human health, efficiency, risks and uncertainty, animal welfare, animal dignity, environmental considerations and public acceptability. Our findings illuminate several key considerations about the academic debate, including a low disciplinary diversity in the contributing academics, a scarcity of systematic comparisons of potential consequences of using these technologies, an underrepresentation of animal interests, and a disjunction between the public and academic debate on this topic. As such, this article can be considered a call for a broad range of academics to get increasingly involved in the discussion about genome editing, to incorporate animal interests and systematic comparisons, and to further discuss the aims and methods of public involvement. This article is part of a discussion meeting issue 'The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems'.

Organs to Cells and Cells to Organoids: The Evolution of in vitro Central Nervous System Modelling

With 100 billion neurons and 100 trillion synapses, the human brain is not just the most complex organ in the human body, but has also been described as "the most complex thing in the universe." The limited availability of human living brain tissue for the study of neurogenesis, neural processes and neurological disorders has resulted in more than a century-long strive from researchers worldwide to model the central nervous system (CNS) and dissect both its striking physiology and enigmatic pathophysiology. The invaluable knowledge gained with the use of animal models and post mortem human tissue remains limited to cross-species similarities and structural features, respectively. The advent of human induced pluripotent stem cell (hiPSC) and 3-D organoid technologies has revolutionised the approach to the study of human brain and CNS in vitro, presenting great potential for disease modelling and translational adoption in drug screening and regenerative medicine, also contributing beneficially to clinical research. We have surveyed more than 100 years of research in CNS modelling and provide in this review an historical excursus of its evolution, from early neural tissue explants and organotypic cultures, to 2-D patient-derived cell monolayers, to the latest development of 3-D cerebral organoids. We have generated a comprehensive summary of CNS modelling techniques and approaches, protocol refinements throughout the course of decades and developments in the study of specific neuropathologies. Current limitations and caveats such as clonal variation, developmental stage, validation of pluripotency and chromosomal stability, functional assessment, reproducibility, accuracy and scalability of these models are also discussed.

Pluripotent Stem Cells for Retinal Tissue Engineering: Current Status and Future Prospects

The retina is a very fine and layered neural tissue, which vitally depends on the preservation of cells, structure, connectivity and vasculature to maintain vision. There is an urgent need to find technical and biological solutions to major challenges associated with functional replacement of retinal cells. The major unmet challenges include generating sufficient numbers of specific cell types, achieving functional integration of transplanted cells, especially photoreceptors, and surgical delivery of retinal cells or tissue without triggering immune responses, inflammation and/or remodeling. The advances of regenerative medicine enabled generation of three-dimensional tissues (organoids), partially recreating the anatomical structure, biological complexity and physiology of several tissues, which are important targets for stem cell replacement therapies. Derivation of retinal tissue in a dish creates new opportunities for cell replacement therapies of blindness and addresses the need to preserve retinal architecture to restore vision. Retinal cell therapies aimed at preserving and improving vision have achieved many improvements in the past ten years. Retinal organoid technologies provide a number of solutions to technical and biological challenges associated with functional replacement of retinal cells to achieve long-term vision restoration. Our review summarizes the progress in cell therapies of retina, with focus on human pluripotent stem cell-derived retinal tissue, and critically evaluates the potential of retinal organoid approaches to solve a major unmet clinical need—retinal repair and vision restoration in conditions caused by retinal degeneration and traumatic ocular injuries. We also analyze obstacles in commercialization of retinal organoid technology for clinical application.

Chimeric Antigen Receptor T Cells: Extending Translation from Liquid to Solid Tumors

Successful translation of chimeric antigen receptor (CAR) T cells designed to target and eradicate CD19+ lymphomas has emboldened scientists and physicians worldwide to explore the possibility of applying CAR T-cell technology to other tumor entities, including solid tumors. Next-generation strategies such as fourth-generation CARs (CAR T cells redirected for universal cytokine killing, also known as TRUCKs) designed to deliver immunomodulatory cytokines to the tumor microenvironment, dual CAR designs to improve tumor control, inclusion of suicide genes as safety switches, and precision genome editing are currently being investigated. One major ongoing goal is to determine how best to generate CAR T cells that modulate the tumor microenvironment, overcome tumor survival mechanisms, and thus allow broader applicability as universal allogeneic T-cell therapeutics. Development of state-of-the-art and beyond viral vector systems to deliver designer CARs coupled with targeted genome editing is expected to generate more effective off-the-shelf CAR T cells with activity against a greater number of cancer types and importantly solid tumors.

Recent Advances in the Genetics of Schizophrenia

The last decade brought tremendous progress in the field of schizophrenia genetics. As a result of extensive collaborations and multiple technological advances, we now recognize many types of genetic variants that increase the risk. These include large copy number variants, rare coding inherited and de novο variants, and over 100 loci harboring common risk variants. While the type and contribution to the risk vary among genetic variants, there is concordance in the functions of genes they implicate, such as those whose RNA binds the fragile X-related protein FMRP and members of the activity-regulated cytoskeletal complex involved in learning and memory. Gene expression studies add important information on the biology of the disease and recapitulate the same functional gene groups. Studies of alternative phenotypes help us widen our understanding of the genetic architecture of mental function and dysfunction, how diseases overlap not only with each other but also with non-disease phenotypes. The challenge is to apply this new knowledge to prevention and treatment and help patients. The data generated so far and emerging technologies, including new methods in cell engineering, offer significant promise that in the next decade we will unlock the translational potential of these significant discoveries.

Inducible CRISPR genome editing platform in naive human embryonic stem cells reveals JARID2 function in self-renewal

To easily edit the genome of naïve human embryonic stem cells (hESC), we introduced a dual cassette encoding an inducible Cas9 into the AAVS1 site of naïve hESC (iCas9). The iCas9 line retained karyotypic stability, expression of pluripotency markers, differentiation potential, and stability in 5iLA and EPS pluripotency conditions. The iCas9 line induced efficient homology-directed repair (HDR) and non-homologous end joining (NHEJ) based mutations through CRISPR-Cas9 system. We utilized the iCas9 line to study the epigenetic regulator, PRC2 in early human pluripotency. The PRC2 requirement distinguishes between early pluripotency stages, however, what regulates PRC2 activity in these stages is not understood. We show reduced H3K27me3 and pluripotency markers in JARID2 2iL-I-F hESC mutants, indicating JARID2 requirement in maintenance of hESC 2iL-I-F state. These data suggest that JARID2 regulates PRC2 in 2iL-I-F state and the lack of PRC2 function in 5iLA state may be due to lack of sufficient JARID2 protein.

Can Human Pluripotent Stem Cell-Derived Cardiomyocytes Advance Understanding of Muscular Dystrophies?

Muscular dystrophies (MDs) are clinically and molecularly a highly heterogeneous group of single-gene disorders that primarily affect striated muscles. Cardiac disease is present in several MDs where it is an important contributor to morbidity and mortality. Careful monitoring of cardiac issues is necessary but current management of cardiac involvement does not effectively protect from disease progression and cardiac failure. There is a critical need to gain new knowledge on the diverse molecular underpinnings of cardiac disease in MDs in order to guide cardiac treatment development and assist in reaching a clearer consensus on cardiac disease management in the clinic. Animal models are available for the majority of MDs and have been invaluable tools in probing disease mechanisms and in pre-clinical screens. However, there are recognized genetic, physiological, and structural differences between human and animal hearts that impact disease progression, manifestation, and response to pharmacological interventions. Therefore, there is a need to develop parallel human systems to model cardiac disease in MDs. This review discusses the current status of cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSC) to model cardiac disease, with a focus on Duchenne muscular dystrophy (DMD) and myotonic dystrophy (DM1). We seek to provide a balanced view of opportunities and limitations offered by this system in elucidating disease mechanisms pertinent to human cardiac physiology and as a platform for treatment development or refinement.

3D bioprinting using stem cells

Recent advances have allowed for three-dimensional (3D) printing technologies to be applied to biocompatible materials, cells and supporting components, creating a field of 3D bioprinting that holds great promise for artificial organ printing and regenerative medicine. At the same time, stem cells, such as human induced pluripotent stem cells, have driven a paradigm shift in tissue regeneration and the modeling of human disease, and represent an unlimited cell source for tissue regeneration and the study of human disease. The ability to reprogram patient-specific cells holds the promise of an enhanced understanding of disease mechanisms and phenotypic variability. 3D bioprinting has been successfully performed using multiple stem cell types of different lineages and potency. The type of 3D bioprinting employed ranged from microextrusion bioprinting, inkjet bioprinting, laser-assisted bioprinting, to newer technologies such as scaffold-free spheroid-based bioprinting. This review discusses the current advances, applications, limitations and future of 3D bioprinting using stem cells, by organ systems.

Mechanism of human somatic reprogramming to iPS cell

Somatic reprogramming to induced pluripotent stem cells (iPSC) was realized in the year 2006 in mice, and in 2007 in humans, by transiently forced expression of a combination of exogenous transcription factors. Human and mouse iPSCs are distinctly reprogrammed into a 'primed' and a 'naïve' state, respectively. In the last decade, puzzle pieces of somatic reprogramming have been collected with difficulty. Collectively, dissecting reprogramming events and identification of the hallmark of sequentially activated/silenced genes have revealed mouse somatic reprogramming in fragments, but there is a long way to go toward understanding the molecular mechanisms of human somatic reprogramming, even with developing technologies. Recently, an established human intermediately reprogrammed stem cell (iRSC) line, which has paused reprogramming at the endogenous OCT4-negative/exogenous transgene-positive pre-MET (mesenchymal-to-epithelial-transition) stage can resume reprogramming into endogenous OCT4-positive iPSCs only by change of culture conditions. Genome-editing-mediated visualization of endogenous OCT4 activity with GFP in living iRSCs demonstrates the timing of OCT4 activation and entry to MET in the reprogramming toward iPSCs. Applications of genome-editing technology to pluripotent stem cells will reshape our approaches for exploring molecular mechanisms.

Hepatitis C virus-induced innate immune responses in human iPS cell-derived hepatocyte-like cells

Hepatitis C virus (HCV) infection is a major cause of liver-related morbidity and mortality. In order to develop effective remedies for hepatitis C, it is important to understand the HCV infection profile and host-HCV interaction. HCV-induced innate immune responses play a crucial role in spontaneous HCV clearance; however, HCV-induced innate immune responses have not been fully evaluated in hepatocytes, partly because there are few in vitro models of HCV-induced innate immunity. Recently, human induced pluripotent stem (iPS) cells have received much attention as an in vitro model of infection with various pathogens, including HCV. We previously established highly functional hepatocyte-like cells differentiated from human iPS cells (iPS-HLCs). Here, we examined the potential of iPS-HLCs as an in vitro HCV infection model, especially for evaluation of the relationship between HCV infection levels and HCV-induced innate immunity. Significant expressions of type I and III interferons (IFNs) and IFN-stimulated genes (ISGs) were induced following transfection with HCV genomic replicon RNA in iPS-HLCs. Following inoculation with the HCV JFH-1 strain in iPS-HLCs, peaks of HCV genome replication and HCV protein expression were observed on day 2, and then both the HCV genome and protein levels gradually declined, while the mRNA levels of type III IFNs and ISGs peaked at day 2 following inoculation. These results suggest that the HCV genome efficiently replicates in iPS-HLCs, resulting in HCV genome-induced up-regulation of IFNs and ISGs, and thereafter, HCV genome-induced up-regulation of IFNs and ISGs mediates a reduction in the HCV genome and protein levels in iPS-HLCs.

Genome Editing and Muscle Stem Cells as a Therapeutic Tool for Muscular Dystrophies

Purpose of Review

Muscular dystrophies are a group of severe degenerative disorders characterized by muscle fiber degeneration and death. Therapies designed to restore muscle homeostasis and to replace dying fibers are being experimented, but none of those in clinical trials are suitable to permanently address individual gene mutation. The purpose of this review is to discuss genome editing tools such as CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated), which enable direct sequence alteration and could potentially be adopted to correct the genetic defect leading to muscle impairment.

Recent Findings

Recent findings show that advances in gene therapy, when combined with traditional viral vector-based approaches, are bringing the field of regenerative medicine closer to precision-based medicine.

Summary

The use of such programmable nucleases is proving beneficial for the creation of more accurate in vitro and in vivo disease models. Several gene and cell-therapy studies have been performed on satellite cells, the primary skeletal muscle stem cells involved in muscle regeneration. However, these have mainly been based on artificial replacement or augmentation of the missing protein. Satellite cells are a particularly appealing target to address these innovative technologies for the treatment of muscular dystrophies.

Regulation of Stem Cell Properties of Müller Glia by JAK/STAT and MAPK Signaling in the Mammalian Retina

In humans and other mammals, the neural retina does not spontaneously regenerate, and damage to the retina that kills retinal neurons results in permanent blindness. In contrast to embryonic stem cells, induced pluripotent stem cells, and embryonic/fetal retinal stem cells, Müller glia offer an intrinsic cellular source for regenerative strategies in the retina. Müller glia are radial glial cells within the retina that maintain retinal homeostasis, buffer ion flux associated with phototransduction, and form the blood/retinal barrier within the retina proper. In injured or degenerating retinas, Müller glia contribute to gliotic responses and scar formation but also show regenerative capabilities that vary across species. In the mammalian retina, regenerative responses achieved to date remain insufficient for potential clinical applications. Activation of JAK/STAT and MAPK signaling by CNTF, EGF, and FGFs can promote proliferation and modulate the glial/neurogenic switch. However, to achieve clinical relevance, additional intrinsic and extrinsic factors that restrict or promote regenerative responses of Müller glia in the mammalian retina must be identified. This review focuses on Müller glia and Müller glial-derived stem cells in the retina and phylogenetic differences among model vertebrate species and highlights some of the current progress towards understanding the cellular mechanisms regulating their regenerative response.

Prospects of Pluripotent and Adult Stem Cells for Rare Diseases

Rare diseases are highly diverse and complex regarding molecular underpinning and clinical manifestation and afflict millions of patients worldwide. The lack of appropriate model systems with face and construct validity and the limited availability of live tissues and cells from patients has largely hampered the understanding of underlying disease mechanisms. As a consequence, there are no adequate treatment options available for the vast majority of rare diseases. Over the last decade, remarkable progress in pluripotent and adult stem cell biology and the advent of powerful genomic technologies opened up exciting new avenues for the investigation, diagnosis, and personalized therapy of intractable human diseases. Utilizing the entire range of available stem cell types will continue to cross-fertilize different research areas and leverage the investigation of rare diseases based on evidence-based medicine. Standardized cell engineering and manufacturing from inexhaustible stem cell sources should lay the foundation for next-generation drug discovery and cell therapies that are broadly applicable in regenerative medicine. In this chapter we discuss how patient- and disease-specific iPS cells as well as adult stem cells are changing the pace of biomedical research and the translational landscape.

Recent Advances in the Molecular Genetics of Familial Hypertrophic Cardiomyopathy in South Asian Descendants

The South Asian population, numbered at 1.8 billion, is estimated to comprise around 20% of the global population and 1% of the American population, and has one of the highest rates of cardiovascular disease. While South Asians show increased classical risk factors for developing heart failure, the role of population-specific genetic risk factors has not yet been examined for this group. Hypertrophic cardiomyopathy (HCM) is one of the major cardiac genetic disorders among South Asians, leading to contractile dysfunction, heart failure, and sudden cardiac death. This disease displays autosomal dominant inheritance, and it is associated with a large number of variants in both sarcomeric and non-sarcomeric proteins. The South Asians, a population with large ethnic diversity, potentially carries region-specific polymorphisms. There is high variability in disease penetrance and phenotypic expression of variants associated with HCM. Thus, extensive studies are required to decipher pathogenicity and the physiological mechanisms of these variants, as well as the contribution of modifier genes and environmental factors to disease phenotypes. Conducting genotype-phenotype correlation studies will lead to improved understanding of HCM and, consequently, improved treatment options for this high-risk population. The objective of this review is to report the history of cardiovascular disease and HCM in South Asians, present previously published pathogenic variants, and introduce current efforts to study HCM using induced pluripotent stem cell-derived cardiomyocytes, next-generation sequencing, and gene editing technologies. The authors ultimately hope that this review will stimulate further research, drive novel discoveries, and contribute to the development of personalized medicine with the aim of expanding therapeutic strategies for HCM.