Urine-sample-derived human induced pluripotent stem cells as a model to study PCSK9-mediated autosomal dominant hypercholesterolemia

Challenges of therapeutic applications and regenerative capacities of urine based stem cells in oral, and maxillofacial reconstruction

Urine-derived stem cells (USCs) have gained the attention of researchers in the biomedical field in the past few years . Regarding the several varieties of cells that have been used for this purpose, USCs have demonstrated mesenchymal stem cell-like properties, such as differentiation and immunomodulation. Furthermore, they could be differentiated into several lineages. This is very interesting for regenerative techniques based on cell therapy. This review will embark on describing their separation, and profiling. We will specifically describe the USCs characteristics, in addition to their differentiation potential. Then, we will introduce and explore the primary uses of USCs. These involve thier utilization as a platform to produce stem cells, however, we shall concentrate on the utilization of USCs for therapeutic, and regenerative orofacial applications, providing an in-depth evaluation of this purpose. The final portion will address the limitations and challenges of their implementation in regenerative dentistry.

Human induced pluripotent stem cells-derived liver organoids grown on a Biomimesys® hyaluronic acid-based hydroscaffold as a new model for studying human lipoprotein metabolism

The liver plays a key role in the metabolism of lipoproteins, controlling both production and catabolism. To accelerate the development of new lipid-lowering therapies in humans, it is essential to have a relevant in vitro study model available. The current hepatocyte-like cells (HLCs) models derived from hiPSC can be used to model many genetically driven diseases but require further improvement to better recapitulate the complexity of liver functions. Here, we aimed to improve the maturation of HLCs using a three-dimensional (3D) approach using Biomimesys®, a hyaluronic acid-based hydroscaffold in which hiPSCs may directly form aggregates and differentiate toward a functional liver organoid model. After a 28-day differentiation 3D protocol, we showed that many hepatic genes were upregulated in the 3D model (liver organoids) in comparison with the 2D model (HLCs). Liver organoids, grown on Biomimesys®, exhibited an autonomous cell organization, were composed of different cell types and displayed enhanced cytochromes P450 activities compared to HLCs. Regarding the functional capacities of these organoids, we showed that they were able to accumulate lipids (hepatic steatosis), internalize low-density lipoprotein and secrete apolipoprotein B. Interestingly, we showed for the first time that this model was also able to produce apolipoprotein (a), the apolipoprotein (a) specific of Lp(a). This innovative hiPSC-derived liver organoid model may serve as a relevant model for studying human lipopoprotein metabolism, including Lp(a).

Exploiting urine-derived induced pluripotent stem cells for advancing precision medicine in cell therapy, disease modeling, and drug testing

The field of regenerative medicine has witnessed remarkable advancements with the emergence of induced pluripotent stem cells (iPSCs) derived from a variety of sources. Among these, urine-derived induced pluripotent stem cells (u-iPSCs) have garnered substantial attention due to their non-invasive and patient-friendly acquisition method. This review manuscript delves into the potential and application of u-iPSCs in advancing precision medicine, particularly in the realms of drug testing, disease modeling, and cell therapy. U-iPSCs are generated through the reprogramming of somatic cells found in urine samples, offering a unique and renewable source of patient-specific pluripotent cells. Their utility in drug testing has revolutionized the pharmaceutical industry by providing personalized platforms for drug screening, toxicity assessment, and efficacy evaluation. The availability of u-iPSCs with diverse genetic backgrounds facilitates the development of tailored therapeutic approaches, minimizing adverse effects and optimizing treatment outcomes. Furthermore, u-iPSCs have demonstrated remarkable efficacy in disease modeling, allowing researchers to recapitulate patient-specific pathologies in vitro. This not only enhances our understanding of disease mechanisms but also serves as a valuable tool for drug discovery and development. In addition, u-iPSC-based disease models offer a platform for studying rare and genetically complex diseases, often underserved by traditional research methods. The versatility of u-iPSCs extends to cell therapy applications, where they hold immense promise for regenerative medicine. Their potential to differentiate into various cell types, including neurons, cardiomyocytes, and hepatocytes, enables the development of patient-specific cell replacement therapies. This personalized approach can revolutionize the treatment of degenerative diseases, organ failure, and tissue damage by minimizing immune rejection and optimizing therapeutic outcomes. However, several challenges and considerations, such as standardization of reprogramming protocols, genomic stability, and scalability, must be addressed to fully exploit u-iPSCs' potential in precision medicine. In conclusion, this review underscores the transformative impact of u-iPSCs on advancing precision medicine and highlights the future prospects and challenges in harnessing this innovative technology for improved healthcare outcomes.

Urine-derived stem cells: Promising advancements and applications in regenerative medicine and beyond

Currently, stem cells are a prominent focus of regenerative engineering research. However, due to the limitations of commonly used stem cell sources, their application in therapy is often restricted to the experimental stage and constrained by ethical considerations. In contrast, urine-derived stem cells (USCs) offer promising advantages for clinical trials and applications. The noninvasive nature of the collection process allows for repeated retrieval within a short period, making it a more feasible option. Moreover, studies have shown that USCs have a protective effect on organs, promoting vascular regeneration, inhibiting oxidative stress, and reducing inflammation in various acute and chronic organ dysfunctions. The application of USCs has also been enhanced by advancements in biomaterials technology, enabling better targeting and controlled release capabilities. This review aims to summarize the current state of research on USCs, providing insights for future applications in basic and clinical settings.

Generation of an induced pluripotent stem cell line (ITXi012-A) from a patient with genetically determined high-lipoprotein(a) plasma levels

Elevated circulating lipoprotein(a) (Lp(a)) is a genetically determined risk factor for coronary artery disease and aortic valve stenosis (Tsimikas, 2017). Importantly, the LPA gene, which encodes the apolipoprotein(a) (protein-component of Lp(a)), is missing in most species, and human liver cell-lines do not secrete Lp(a). There is a need for the development of human in vitro models suitable for investigating biological mechanisms involved in Lp(a) metabolism. We here generated and characterized iPSCs from a patient with extremely high Lp(a) plasma levels genetically determined (Coassin et al., 2022). This unique cellular model offers great opportunities and new perspectives for investigations on biological mechanisms involved in Lp(a) metabolism.

Pathological modeling of glycogen storage disease type III with CRISPR/Cas9 edited human pluripotent stem cells

Introduction: Glycogen storage disease type III (GSDIII) is a rare genetic disease caused by mutations in the AGL gene encoding the glycogen debranching enzyme (GDE). The deficiency of this enzyme, involved in cytosolic glycogen degradation, leads to pathological glycogen accumulation in liver, skeletal muscles and heart. Although the disease manifests with hypoglycemia and liver metabolism impairment, the progressive myopathy is the major disease burden in adult GSDIII patients, without any curative treatment currently available. Methods: Here, we combined the self-renewal and differentiation capabilities of human induced pluripotent stem cells (hiPSCs) with cutting edge CRISPR/Cas9 gene editing technology to establish a stable AGL knockout cell line and to explore glycogen metabolism in GSDIII. Results: Following skeletal muscle cells differentiation of the edited and control hiPSC lines, our study reports that the insertion of a frameshift mutation in AGL gene results in the loss of GDE expression and persistent glycogen accumulation under glucose starvation conditions. Phenotypically, we demonstrated that the edited skeletal muscle cells faithfully recapitulate the phenotype of differentiated skeletal muscle cells of hiPSCs derived from a GSDIII patient. We also demonstrated that treatment with recombinant AAV vectors expressing the human GDE cleared the accumulated glycogen. Discussion: This study describes the first skeletal muscle cell model of GSDIII derived from hiPSCs and establishes a platform to study the mechanisms that contribute to muscle impairments in GSDIII and to assess the therapeutic potential of pharmacological inducers of glycogen degradation or gene therapy approaches.

PCSK9: A Multi-Faceted Protein That Is Involved in Cardiovascular Biology

Pro-protein convertase subtilisin/kexin type 9 (PCSK9) is secreted mostly by hepatocytes and to a lesser extent by the intestine, pancreas, kidney, adipose tissue, and vascular cells. PCSK9 has been known to interact with the low-density lipoprotein receptor (LDLR) and chaperones the receptor to its degradation. In this manner, targeting PCSK9 is a novel attractive approach to reduce hyperlipidaemia and the risk for cardiovascular diseases. Recently, it has been recognised that the effects of PCSK9 in relation to cardiovascular complications are not only LDLR related, but that various LDLR-independent pathways and processes are also influenced. In this review, the various LDLR dependent and especially independent effects of PCSK9 on the cardiovascular system are discussed, followed by an overview of related PCSK9-polymorphisms and currently available and future therapeutic approaches to manipulate PCSK9 expression.

Urine-derived induced pluripotent/neural stem cells for modeling neurological diseases

Neurological diseases are mainly modeled using rodents through gene editing, surgery or injury approaches. However, differences between humans and rodents in terms of genetics, neural development, and physiology pose limitations on studying disease pathogenesis in rodent models for neuroscience research. In the past decade, the generation of induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs) by reprogramming somatic cells offers a powerful alternative for modeling neurological diseases and for testing regenerative medicines. Among the different somatic cell types, urine-derived stem cells (USCs) are an ideal cell source for iPSC and iNSC reprogramming, as USCs are highly proliferative, multipotent, epithelial in nature, and easier to reprogram than skin fibroblasts. In addition, the use of USCs represents a simple, low-cost and non-invasive procedure for generating iPSCs/iNSCs. This review describes the cellular and molecular properties of USCs, their differentiation potency, different reprogramming methods for the generation of iPSCs/iNSCs, and their potential applications in modeling neurological diseases.

Urine-derived stem/progenitor cells: A focus on their characterization and potential

Cell therapy, i.e., the use of cells to repair an affected tissue or organ, is at the forefront of regenerative and personalized medicine. Among the multiple cell types that have been used for this purpose [including adult stem cells such as mesenchymal stem cells or pluripotent stem cells], urine-derived stem cells (USCs) have aroused interest in the past years. USCs display classical features of mesenchymal stem cells such as differentiation capacity and immunomodulation. Importantly, they have the main advantage of being isolable from one sample of voided urine with a cheap and unpainful procedure, which is broadly applicable, whereas most adult stem cell types require invasive procedure. Moreover, USCs can be differentiated into renal cell types. This is of high interest for renal cell therapy-based regenerative approaches. This review will firstly describe the isolation and characterization of USCs. We will specifically present USC phenotype, which is not an object of consensus in the literature, as well as detail their differentiation capacity. In the second part of this review, we will present and discuss the main applications of USCs. These include use as a substrate to generate human induced pluripotent stem cells, but we will deeply focus on the use of USCs for cell therapy approaches with a detailed analysis depending on the targeted organ or system. Importantly, we will also focus on the applications that rely on the use of USC-derived products such as microvesicles including exosomes, which is a strategy being increasingly employed. In the last section, we will discuss the remaining barriers and challenges in the field of USC-based regenerative medicine.

Application of CRISPR/Cas9 to human-induced pluripotent stem cells: from gene editing to drug discovery

Human-induced pluripotent stem cells (hiPSCs) and CRISPR/Cas9 gene editing system represent two instruments of basic and translational research, which both allow to acquire deep insight about the molecular bases of many diseases but also to develop pharmacological research.This review is focused to draw up the latest technique of gene editing applied on hiPSCs, exploiting some of the genetic manipulation directed to the discovery of innovative therapeutic strategies. There are many expediencies provided by the use of hiPSCs, which can represent a disease model clinically relevant and predictive, with a great potential if associated to CRISPR/Cas9 technology, a gene editing tool powered by ease and precision never seen before.Here, we describe the possible applications of CRISPR/Cas9 to hiPSCs: from drug development to drug screening and from gene therapy to the induction of the immunological response to specific virus infection, such as HIV and SARS-Cov-2.

Generation of infant- and pediatric-derived urinary induced pluripotent stem cells competent to form kidney organoids

BACKGROUND

Human induced pluripotent stem cells (iPSCs) are a promising tool to investigate pathogenic mechanisms underlying human genetic conditions, such as congenital anomalies of the kidney and urinary tract (CAKUT). Currently, iPSC-based research in pediatrics is limited by the invasiveness of cell collection.

METHODS

Urine cells (UCs) were isolated from pediatric urine specimens, including bag collections, and reprogrammed using episomal vectors into urinary iPSCs (UiPSCs). Following iPSC-quality assessment, human kidney organoids were generated.

RESULTS

UCs were isolated from 71% (12/17) of single, remnant urine samples obtained in an outpatient setting (patients 1 month-17 years, volumes 10-75 ml). Three independent UCs were reprogrammed to UiPSCs with early episome loss, confirmed pluripotency and normal karyotyping. Subsequently, these UiPSCs were successfully differentiated into kidney organoids, closely resembling organoids generated from control fibroblast-derived iPSCs. Importantly, under research conditions with immediate sample processing, UC isolation was successful 100% for target pediatric CAKUT patients and controls (11/11) after at most two urine collections.

CONCLUSIONS

Urine in small volumes or collected in bags is a reliable source for reprogrammable somatic cells that can be utilized to generate kidney organoids. This constitutes an attractive approach for patient-specific iPSC research involving infants and children with wide applicability and a low threshold for participation.

Urine-Derived Stem Cells: Applications in Regenerative and Predictive Medicine

Despite being a biological waste, human urine contains a small population of cells with self-renewal capacity and differentiation potential into several cell types. Being derived from the convoluted tubules of nephron, renal pelvis, ureters, bladder and urethra, urine-derived stem cells (UDSC) have a similar phenotype to mesenchymal stroma cells (MSC) and can be reprogrammed into iPSC (induced pluripotent stem cells). Having simple, safer, low-cost and noninvasive collection procedures, the interest in UDSC has been growing in the last decade. With great potential in regenerative medicine applications, UDSC can also be used as biological models for pharmacology and toxicology tests. This review describes UDSC biological characteristics and differentiation potential and their possible use, including the potential of UDSC-derived iPSC to be used in drug discovery and toxicology, as well as in regenerative medicine. Being a new cellular platform amenable to noninvasive collection for disease stratification and personalized therapy could be a future application for UDSC.

Episomal Induced Pluripotent Stem Cells: Functional and Potential Therapeutic Applications

The term episomal induced pluripotent stem cells (EiPSCs) refers to somatic cells that are reprogrammed into induced pluripotent stem cells (iPSCs) using non-integrative episomal vector methods. This reprogramming process has a better safety profile compared with integrative methods using viruses. There is a current trend toward using episomal plasmid reprogramming to generate iPSCs because of the improved safety profile. Clinical reports of potential human cell sources that have been successfully reprogrammed into EiPSCs are increasing, but no review or summary has been published. The functional applications of EiPSCs and their potential uses in various conditions have been described, and these may be applicable to clinical scenarios. This review summarizes the current direction of EiPSC research and the properties of these cells with the aim of explaining their potential role in clinical applications and functional restoration.

Focal adhesion kinase promotes BMP2-induced osteogenic differentiation of human urinary stem cells via AMPK and Wnt signaling pathways

Human urine-derived stem cells (hUSCs) serve as favorable candidates for bone transplants due to their efficient proliferative and multipotent differentiation abilities, as well as the capacity to secrete a variety of vasoactive agents to facilitate tissue engineering. The present study aimed to explore the role of focal adhesion kinase (FAK) in bone morphogenetic protein 2 (BMP2)-induced osteogenic differentiation of hUSCs and to investigate the underlying mechanism. The degree of osteogenic differentiation and the correlated signals, following BMP2 overexpression and siRNA-mediated silencing of FAK, were determined in vitro. Moreover, hUSCs induced bone formation in a rat model with cranial defects, in vivo. Our findings revealed that alkaline phosphatase production, calcium deposits, osteocalcin and osteopontin expression, and bone formation were upregulated in vitro and in vivo following BMP2-induced osteogenic differentiation, and AMPK and Wnt signaling pathway activation by FAK could effectively regulate BMP2-enhanced osteogenic differentiation of hUSCs. Taken together, these findings indicated that FAK could mediate BMP2-enhanced osteogenic differentiation of hUSCs through activating adenosine 5'-monophosphate-activated protein kinase and Wnt signaling pathways.

Bile-Derived Organoids From Patients With Primary Sclerosing Cholangitis Recapitulate Their Inflammatory Immune Profile

Primary sclerosing cholangitis (PSC) is a heterogeneous and progressive fibroinflammatory cholangiopathy with no known etiology or effective treatment. Studies of PSC are limited due to difficulty in accessing the cholangiocyte, the small percentage of these cells in the liver, instability of in vitro culture systems, and reliance on samples from end-stage disease. Here, we demonstrate that stem cells can be isolated from the bile of PSC patients undergoing endoscopic retrograde cholangiopancreatography earlier in their clinical course and maintained long term in vitro as three-dimensional (3D) organoids that express a biliary genetic phenotype. Additionally, bile-derived organoids (BDOs) can be biobanked and samples obtained longitudinally over the course of the disease. These BDOs express known cholangiocyte markers including gamma glutamyl transferase, cytokeratin 19, epithelial cellular adhesion molecule, cystic fibrosis transmembrane conductance regulator, and anion exchanger 2. RNA sequence analysis identified 39 genes whose expression differed in organoids from PSC patients compared to non-PSC controls, including human leukocyte antigen DM alpha chain and chemokine (C-C motif) ligand 20 (CCL20), immune-related genes previously described in genome-wide association studies of PSC. Incubation of these BDOs with interleukin 17A or tumor necrosis factor alpha led to an immune-reactive phenotype with a significant increase in secretion of proinflammatory mediators, including CCL20, a T-cell chemoattractant. Conclusion: This study demonstrates that bile can be used as a source of biliary-like cells that can be maintained long term in vitro as 3D organoids; these BDOs retain features of cholangiopathies, including the ability to react to inflammatory stimuli by secreting chemokines and propagating an immune-reactive phenotype reflective of the pathogenesis of these diseases; thus, BDOs represent a platform for the study of the pathogenesis and therapy of cholangiopathies, particularly PSC.

Pluripotent stem cell-derived bile canaliculi-forming hepatocytes to study genetic liver diseases involving hepatocyte polarity

BACKGROUND & AIMS

Hepatocyte polarity is essential for the development of bile canaliculi and for safely transporting bile and waste products from the liver. Functional studies of autologous mutated proteins in the context of the polarized hepatocyte have been challenging because of the lack of appropriate cell models. The aims of this study were to obtain a patient-specific hepatocyte model that recapitulated hepatocyte polarity and to employ this model to study endogenous mutant proteins in liver diseases that involve hepatocyte polarity.

METHODS

Urine cell-derived pluripotent stem cells, taken from a patient with a homozygous mutation in ATP7B and a patient with a heterozygous mutation, were differentiated towards hepatocyte-like cells (hiHeps). HiHeps were also derived from a patient with MEDNIK syndrome.

RESULTS

Polarized hiHeps that formed in vivo-like bile canaliculi could be generated from embryonic and patient urine cell-derived pluripotent stem cells. HiHeps recapitulated polarized protein trafficking processes, exemplified by the Cu²⁺-induced redistribution of the copper transporter protein ATP7B to the bile canalicular domain. We demonstrated that, in contrast to the current dogma, the most frequent yet enigmatic Wilson disease-causing ATP7B-H1069Q mutation per se did not preclude trafficking of ATP7B to the trans-Golgi Network. Instead, it prevented its Cu²⁺-induced polarized redistribution to the bile canalicular domain, which could not be reversed by pharmacological folding chaperones. Finally, we demonstrate that hiHeps from a patient with MEDNIK syndrome, suffering from liver copper overload of unclear etiology, showed no defect in the Cu²⁺-induced redistribution of ATP7B to the bile canaliculi.

CONCLUSIONS

Functional cell polarity can be achieved in patient pluripotent stem cell-derived hiHeps, enabling, for the first time, the study of the endogenous mutant proteins, patient-specific pathogenesis and drug responses for diseases where hepatocyte polarity is a key factor.

LAY SUMMARY

This study demonstrates that cells that are isolated from urine can be reprogrammed in a dish towards hepatocytes that display architectural characteristics similar to those seen in the intact liver. The application of this methodology to cells from patients diagnosed with inherited copper metabolism-related liver diseases (that is, Wilson disease and MEDNIK syndrome) revealed unexpected and novel insights into patient mutation-specific disease mechanisms and drug responses.

Urinary Stem Cells as Tools to Study Genetic Disease: Overview of the Literature

Urine specimens represent a novel and non-invasive approach to isolate patient-specific stem cells by easy and low-cost procedures, replacing the traditional sources (muscle/skin biopsy/adipose tissue) obtained with invasive and time-consuming methods. Urine-derived stem cells (USCs) can be used in a broad field of applications, such as regenerative medicine, cell therapy, diagnostic testing, disease modelling and drug screening. USCs are a good source of cells for generating induced pluripotent stem cells (iPSCs) and importantly, they can also be directly converted into specific cell lines. In this review, we show the features of USCs and their use as a promising in vitro model to study genetic diseases.

Pluripotent stem cells: induction and self-renewal

Pluripotent stem cells (PSCs) lie at the heart of modern regenerative medicine due to their properties of unlimited self-renewal in vitro and their ability to differentiate into cell types representative of the three embryonic germ layers-mesoderm, ectoderm and endoderm. The derivation of induced PSCs bypasses ethical concerns associated with the use of human embryonic stem cells and also enables personalized cell-based therapies. To exploit their regenerative potential, it is essential to have a firm understanding of the molecular processes associated with their induction from somatic cells. This understanding serves two purposes: first, to enable efficient, reliable and cost-effective production of excellent quality induced PSCs and, second, to enable the derivation of safe, good manufacturing practice-grade transplantable donor cells. Here, we review the reprogramming process of somatic cells into induced PSCs and associated mechanisms with emphasis on self-renewal, epigenetic control, mitochondrial bioenergetics, sub-states of pluripotency, naive ground state, naive and primed. A meta-analysis identified genes expressed exclusively in the inner cell mass and in the naive but not in the primed pluripotent state. We propose these as additional biomarkers defining naive PSCs.This article is part of the theme issue 'Designer human tissue: coming to a lab near you'.

Patient-Derived Organoids from Human Bile: An In Vitro Method to Study Cholangiopathies

Cholangiopathies, including primary sclerosing cholangitis, are a group of heterogeneous diseases characterized by inflammation and fibrosis of the intrahepatic and extrahepatic bile duct epithelium. Studies, especially of primary sclerosing cholangitis, have been hampered by the difficulty in accessing the cholangiocyte, instability of in vitro culture systems, and reliance on (limited) samples from end-stage disease. Here we describe a novel method of culturing biliary cells from bile of primary sclerosing cholangitis patients undergoing endoscopic retrograde cholangiopancreatography for clinical indications. These 3D organoid cultures demonstrate a biliary phenotype, can be maintained in vitro, and biobanked for future analyses. Given the need for diagnostic and therapeutic endoscopic retrograde cholangiopancreatography throughout the disease in many primary sclerosing cholangitis patients, this method can provide longitudinal studies in individual patients, allowing for a correlation of gene expression with disease status. These organoids can react to inflammatory stimuli, resulting in the secretion of chemo/cytokines indicative of the reactive immune phenotype characteristic of primary sclerosing cholangitis. Therefore, bile-derived organoids provide a model to study the pathogenesis and pharmacotherapeutic treatment of cholangiopathies.

Urine-derived cells provide a readily accessible cell type for feeder-free mRNA reprogramming

Over a decade after their discovery, induced pluripotent stem cells (iPSCs) have become a major biological model. The iPSC technology allows generation of pluripotent stem cells from somatic cells bearing any genomic background. The challenge ahead of us is to translate human iPSCs (hiPSCs) protocols into clinical treatment. To do so, we need to improve the quality of hiPSCs produced. In this study we report the reprogramming of multiple patient urine-derived cell lines with mRNA reprogramming, which, to date, is one of the fastest and most faithful reprogramming method. We show that mRNA reprogramming efficiently generates hiPSCs from urine-derived cells. Moreover, we were able to generate feeder-free bulk hiPSCs lines that did not display genomic abnormalities. Altogether, this reprogramming method will contribute to accelerating the translation of hiPSCs to therapeutic applications.

Generation of Retinal Organoids with Mature Rods and Cones from Urine-Derived Human Induced Pluripotent Stem Cells

Urine cells, a body trash, have been successfully reprogrammed into human induced pluripotent stem cells (U-hiPSCs) which hold a huge promise in regenerative medicine. However, it is unknown whether or to what extent U-hiPSCs can generate retinal cells so far. With a modified retinal differentiation protocol without addition of retinoic acid (RA), our study revealed that U-hiPSCs were able to differentiate towards retinal fates and form 3D retinal organoids containing laminated neural retina with all retinal cell types located in proper layer as in vivo. More importantly, U-hiPSCs generated highly mature photoreceptors with all subtypes, even red/green cone-rich photoreceptors. Our data indicated that a supplement of RA to culture medium was not necessary for maturation and specification of U-hiPSC-derived photoreceptors at least in the niche of retinal organoids. The success of retinal differentiation with U-hiPSCs provides many opportunities in cell therapy, disease modeling, and drug screening, especially in personalized medicine of retinal diseases since urine cells can be noninvasively collected from patients and their relatives.

Stem cell modeling of lipid genetics

PURPOSE OF REVIEW

To summarize recent advances with respect to the use of human pluripotent stem cells to study the genetics of blood lipid traits.

RECENT FINDINGS

Human pluripotent stem cell models have been used to elucidate the mechanisms by which genes contribute to dyslipidemia, to discover new lipid-related DNA variants and genes, and to perform drug screens.

SUMMARY

In addition to enabling a better understanding of the genetic basis of lipid metabolism, human pluripotent stem cells are identifying potential therapeutic targets as well as potential therapies.

Induced Pluripotent Stem Cells for Cardiovascular Disease Modeling and Precision Medicine: A Scientific Statement From the American Heart Association

Induced pluripotent stem cells (iPSCs) offer an unprece-dented opportunity to study human physiology and disease at the cellular level. They also have the potential to be leveraged in the practice of precision medicine, for example, personalized drug testing. This statement comprehensively describes the provenance of iPSC lines, their use for cardiovascular disease modeling, their use for precision medicine, and strategies through which to promote their wider use for biomedical applications. Human iPSCs exhibit properties that render them uniquely qualified as model systems for studying human diseases: they are of human origin, which means they carry human genomes; they are pluripotent, which means that in principle, they can be differentiated into any of the human body's somatic cell types; and they are stem cells, which means they can be expanded from a single cell into millions or even billions of cell progeny. iPSCs offer the opportunity to study cells that are genetically matched to individual patients, and genome-editing tools allow introduction or correction of genetic variants. Initial progress has been made in using iPSCs to better understand cardiomyopathies, rhythm disorders, valvular and vascular disorders, and metabolic risk factors for ischemic heart disease. This promising work is still in its infancy. Similarly, iPSCs are only just starting to be used to identify the optimal medications to be used in patients from whom the cells were derived. This statement is intended to (1) summarize the state of the science with respect to the use of iPSCs for modeling of cardiovascular traits and disorders and for therapeutic screening; (2) identify opportunities and challenges in the use of iPSCs for disease modeling and precision medicine; and (3) outline strategies that will facilitate the use of iPSCs for biomedical applications. This statement is not intended to address the use of stem cells as regenerative therapy, such as transplantation into the body to treat ischemic heart disease or heart failure.

Urine-Derived Stem Cells: The Present and the Future

Stem cell research provides promising strategies in improving healthcare for human beings. As a noninvasively obtained and easy-to-culture cell resource with relatively low expense, urine-derived stem cells have special advantages. They have been extensively studied on its proliferation ability and differentiation potential and were being reprogrammed to model diseases during the last decade. In this review, we intend to summarize the latest progress on the research of urine-derived stem cells for its broad application mainly in regenerative medicine and disease modeling, as well as in what is challenging currently. This minireview will highlight the potential application of urine-derived stem cells and provides possible direction of further research in the future.

Roux-en-Y gastric bypass reduces plasma cholesterol in diet-induced obese mice by affecting trans-intestinal cholesterol excretion and intestinal cholesterol absorption

OBJECTIVE

Bariatric surgery appears as the most efficient therapeutic alternative in morbidly obese patients. In addition to its efficiency to decrease body weight, it also improves metabolic complications associated to morbid obesity, including dyslipidemia. Although the cholesterol-lowering effect varies with the bariatric procedures, the underlying molecular mechanisms remain poorly defined. This study aims to assess the consequence of both restrictive (sleeve gastrectomy; SG) and malabsorptive (Roux-en-Y gastric bypass; RYGB) procedures on cholesterol metabolism in mice.

SUBJECTS

Ten-week-old C57BL6/J males were fed with a high-fat diet for 8-14 weeks before sleeve or RYGB surgery.

RESULTS

SG has a modest and transient effect on plasma cholesterol levels, linked to a reduction in food intake. In contrast, modified RYGB led to a sustained ≈35% reduction in plasma cholesterol concentrations with a drastic increase in fecal cholesterol output. Mechanistically, RYGB exerts a synergystic effect on cholesterol metabolism by inducing the trans-intestinal cholesterol efflux and reducing the intestinal cholesterol absorption.

CONCLUSIONS

In mice, RYGB, but not sleeve, strongly favors plasma cholesterol elimination by concomitantly increasing trans-intestinal cholesterol excretion and by decreasing intestinal cholesterol absorption. Our models open new perspective for deciphering the hypocholesterolemic effects of bariatric procedures.

Generation of Integration-Free Induced Pluripotent Stem Cells from Urine-Derived Cells Isolated from Individuals with Down Syndrome

Down syndrome (DS) is a genetic disorder caused by trisomy 21 (T21). Over the past two decades, the use of mouse models has led to significant advances in the understanding of mechanisms underlying various phenotypic features and comorbidities secondary to T21 and even informed the design of clinical trials aimed at enhancing the cognitive abilities of persons with DS. In spite of its success, this approach has been plagued by all the typical limitations of rodent modeling of human disorders and diseases. Recently, several laboratories have succeeded in producing T21 human induced pluripotent stem cells (T21-iPSCs) from individuals with DS, which is emerging as a promising complementary tool for the study of DS. Here, we describe the method by which we generated 10 T21-iPSC lines from epithelial cells in urine samples, presumably from kidney epithelial origin, using nonintegrating episomal vectors. We also show that these iPSCs maintain chromosomal stability for well over 20 passages and are more sensitive to proteotoxic stress than euploid iPSCs. Furthermore, these iPSC lines can be differentiated into glutamatergic neurons and cardiomyocytes. By culturing urine-derived cells and maximizing the efficiency of episomal vector transfection, we have been able to generate iPSCs noninvasively and effectively from participants with DS in an ongoing clinical trial, and thus address most shortcomings of previously generated T21-iPSC lines. These techniques should extend the application of iPSCs in modeling DS and other neurodevelopmental and neurodegenerative disorders, and may lead to future human cell-based platforms for high-throughput drug screening. Stem Cells Translational Medicine 2017;6:1465-1476.

Generation of Human Liver Chimeric Mice with Hepatocytes from Familial Hypercholesterolemia Induced Pluripotent Stem Cells

Familial hypercholesterolemia (FH) causes elevation of low-density lipoprotein cholesterol (LDL-C) in blood and carries an increased risk of early-onset cardiovascular disease. A caveat for exploration of new therapies for FH is the lack of adequate experimental models. We have created a comprehensive FH stem cell model with differentiated hepatocytes (iHeps) from human induced pluripotent stem cells (iPSCs), including genetically engineered iPSCs, for testing therapies for FH. We used FH iHeps to assess the effect of simvastatin and proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies on LDL-C uptake and cholesterol lowering in vitro. In addition, we engrafted FH iHeps into the liver of Ldlr^-/-/Rag2^-/-/Il2rg^-/- mice, and assessed the effect of these same medications on LDL-C clearance and endothelium-dependent vasodilation in vivo. Our iHep models recapitulate clinical observations of higher potency of PCSK9 antibodies compared with statins for reversing the consequences of FH, demonstrating the utility for preclinical testing of new therapies for FH patients.

Human Induced Pluripotent Stem (hiPS) Cells from Urine Samples: A Non-Integrative and Feeder-Free Reprogramming Strategy

Human induced pluripotent stem (hiPS) cell technology has already revolutionized some aspects of fundamental and applied research such as study of disease mechanisms and pharmacology screening. The first clinical trial using hiPS cell-derived cells began in Japan, only 10 years after the publication of the proof-of concept article. In this exciting context, strategies to generate hiPS cells have evolved quickly, tending towards non-invasive protocols to sample somatic cells combined with "safer" reprogramming strategies. In this unit, we describe a protocol combining both of these advantages to generate hiPS cells with episomal plasmid transfection from urine samples of individuals carrying the desired genotype. Based on previous published works, this simplified protocol requires minimal equipment and reagents, and is suitable both for scientists familiar with the hiPS cells technology and neophytes. HiPS cells displaying classical features of pluripotency and suitable for all desired downstream applications are generated rapidly (<10 weeks) and with high efficiency. © 2017 by John Wiley & Sons, Inc.

Evaluation of Therapeutic Oligonucleotides for Familial Amyloid Polyneuropathy in Patient-Derived Hepatocyte-Like Cells

Familial amyloid polyneuropathy (FAP) is caused by mutations of the transthyretin (TTR) gene, predominantly expressed in the liver. Two compounds that knockdown TTR, comprising a small interfering RNA (siRNA; ALN-TTR-02) and an antisense oligonucleotide (ASO; IONIS-TTRRx), are currently being evaluated in clinical trials. Since primary hepatocytes from FAP patients are rarely available for molecular analysis and commercial tissue culture cells or animal models lack the patient-specific genetic background, this study uses primary cells derived from urine of FAP patients. Urine-derived cells were reprogrammed to induced pluripotent stem cells (iPSCs) with high efficiency. Hepatocyte-like cells (HLCs) showing typical hepatic marker expression were obtained from iPSCs of the FAP patients. TTR mRNA expression of FAP HLCs almost reached levels measured in human hepatocytes. To assess TTR knockdown, siTTR1 and TTR-ASO were introduced to HLCs. A significant downregulation (>80%) of TTR mRNA was induced in the HLCs by both oligonucleotides. TTR protein present in the cell culture supernatant of HLCs was similarly downregulated. Gene expression of other hepatic markers was not affected by the therapeutic oligonucleotides. Our data indicate that urine cells (UCs) after reprogramming and hepatic differentiation represent excellent primary human target cells to assess the efficacy and specificity of novel compounds.

Hepatocyte-like cells derived from induced pluripotent stem cells

The discovery that coordinated expression of a limited number of genes can reprogram differentiated somatic cells to induced pluripotent stem cells (iPSC) has opened novel possibilities for developing cell-based models of diseases and regenerative medicine utilizing cell reprogramming or cell transplantation. Directed differentiation of iPSCs can potentially generate differentiated cells belonging to any germ layer, including cells with hepatocyte-like morphology and function. Such cells, termed iHeps, can be derived by sequential cell signaling using available information on embryological development or by forced expression of hepatocyte-enriched transcription factors. In addition to the translational aspects of iHeps, the experimental findings have provided insights into the mechanisms of cell plasticity that permit one cell type to transition to another. However, iHeps generated by current methods do not fully exhibit all characteristics of mature hepatocytes, highlighting the need for additional research in this area. Here we summarize the current approaches and achievements in this field and discuss some existing hurdles and emerging approaches for improving iPSC differentiation, as well as maintaining such cells in culture for increasing their utility in disease modeling and drug development.

The potential of induced pluripotent stem cell derived hepatocytes

Orthotopic liver transplantation remains the only curative treatment for liver disease. However, the number of patients who die while on the waiting list (15%) has increased in recent years as a result of severe organ shortages; furthermore the incidence of liver disease is increasing worldwide. Clinical trials involving hepatocyte transplantation have provided encouraging results. However, transplanted cell function appears to often decline after several months, necessitating liver transplantation. The precise aetiology of the loss of cell function is not clear, but poor engraftment and immune-mediated loss appear to be important factors. Also, primary human hepatocytes (PHH) are not readily available, de-differentiate, and die rapidly in culture. Hepatocytes are available from other sources, such as tumour-derived human hepatocyte cell lines and immortalised human hepatocyte cell lines or porcine hepatocytes. However, all these cells suffer from various limitations such as reduced or differences in functions or risk of zoonotic infections. Due to their significant potential, one possible inexhaustible source of hepatocytes is through the directed differentiation of human induced pluripotent stem cells (hiPSCs). This review will discuss the potential applications and existing limitations of hiPSC-derived hepatocytes in regenerative medicine, drug screening, in vitro disease modelling and bioartificial livers.

[Human pluripotent stem cells and liver disorders]

The liver is associated with many diseases including metabolic and cholestatic diseases, cirrhosis as well as chronic and acute hepatitis. However, knowledge about the mechanisms involved in the pathophysiology of these diseases remains limited due to the restricted access to liver biopsies and the lack of cellular models derived from patients. The liver is the main organ responsible for the elimination of xenobiotics and thus hepatocytes have a key role in toxicology and pharmacokinetics. The induced pluripotent stem cells generated from patients with monogenic metabolic disorders, for which the corresponding gene is identified, are relevant in vitro models for the study of the mechanisms involved in generation of pathologies and also for drug screening. Towards this aim, robust protocols for generating liver cells, such as hepatocytes and cholangiocytes, are essential. Our study focused on familial hypercholesterolemia disease modeling, as well as on establishing a protocol for generation of functional cholangiocytes from pluripotent stem cells.

Human Urinary Epithelial Cells as a Source of Engraftable Hepatocyte-Like Cells Using Stem Cell Technology

Although several types of somatic cells have been reprogrammed into induced pluripotent stem cells (iPSCs) and then differentiated to hepatocyte-like cells (iHeps), the method for generating such cells from renal tubular epithelial cells shed in human urine and transplanting them into animal livers has not been described systematically. We report reprogramming of human urinary epithelial cells into iPSCs and subsequent hepatic differentiation, followed by a detailed characterization of the newly generated iHeps. The epithelial cells were reprogrammed into iPSCs by delivering the pluripotency factors OCT3/4, SOX2, KLF4, and MYC using methods that do not involve transgene integration, such as nucleofection of episomal (oriP/EBNA-1) plasmids or infection with recombinant Sendai viruses. After characterization of stable iPSC lines, a three-step differentiation toward hepatocytes was performed. The iHeps expressed a large number of hepatocyte-preferred genes, including nuclear receptors that regulate genes involved in cholesterol homeostasis, bile acid transport, and detoxification. MicroRNA profile of the iHeps largely paralleled that of primary human hepatocytes. The iHeps engrafted into the livers of Scid mice transgenic for mutant human SERPINA1 after intrasplenic injection. Thus, urine is a readily available source for generating human iHeps that could be potentially useful for disease modeling, pharmacological development, and regenerative medicine.

New developments in proprotein convertase subtilisin-kexin 9's biology and clinical implications

PURPOSE OF REVIEW

High levels of LDL-cholesterol (LDL-C) are directly associated with devastating cardiovascular complications. Statins downregulate cholesterol synthesis and upregulate hepatic mRNA levels of LDL receptor (LDLR) and proprotein convertase subtilisin-kexin 9 (PCSK9), a validated enhancer of LDLR protein degradation. Herein, we summarize recent discoveries of the biological properties of PCSK9 in both health and disease states.

RECENT FINDINGS

PCSK9 downregulation of the LDLR protein likely explains the observed protective effect of the loss of PCSK9 in reducing lipoprotein(a) and incidence of septic shock. Injectable inhibitory PCSK9 monoclonal antibodies are now prescribed to hypercholesterolemic patients that do not reach target levels of LDL-C with available drugs. PCSK9 also reduces the levels of other receptors, for example, VLDL receptor (VLDLR), ApoER2, CD36, and CD81. The efficacy of the upregulation of LDLR and VLDLR cell surface levels in the absence of PCSK9 is both tissue and sex dependent. As LDLR, CD81, and VLDLR are hepatitis C receptors, PCSK9 may protect against certain viral infections.

SUMMARY

New functions of PCSK9 and other receptor targets are beginning to emerge to explain the observed changes in LDL-C and triglycerides. The effect of PCSK9 loss-of-function on glucose metabolism, factors that regulate the expression of PCSK9, and the roles of PCSK9 in other tissues, for example, intestine, kidney, and brain require further investigations.