Induced pluripotent stem cells (iPSCs): molecular mechanisms of induction and applications

Human induced pluripotent stem cell-derived therapies for regeneration after central nervous system injury

In recent years, the progression of stem cell therapies has shown great promise in advancing the nascent field of regenerative medicine. Considering the non-regenerative nature of the mature central nervous system, the concept that "blank" cells could be reprogrammed and functionally integrated into host neural networks remained intriguing. Previous work has also demonstrated the ability of such cells to stimulate intrinsic growth programs in post-mitotic cells, such as neurons. While embryonic stem cells demonstrated great potential in treating central nervous system pathologies, ethical and technical concerns remained. These barriers, along with the clear necessity for this type of treatment, ultimately prompted the advent of induced pluripotent stem cells. The advantage of pluripotent cells in central nervous system regeneration is multifaceted, permitting differentiation into neural stem cells, neural progenitor cells, glia, and various neuronal subpopulations. The precise spatiotemporal application of extrinsic growth factors in vitro, in addition to microenvironmental signaling in vivo, influences the efficiency of this directed differentiation. While the pluri- or multipotency of these cells is appealing, it also poses the risk of unregulated differentiation and teratoma formation. Cells of the neuroectodermal lineage, such as neuronal subpopulations and glia, have been explored with varying degrees of success. Although the risk of cancer or teratoma formation is greatly reduced, each subpopulation varies in effectiveness and is influenced by a myriad of factors, such as the timing of the transplant, pathology type, and the ratio of accompanying progenitor cells. Furthermore, successful transplantation requires innovative approaches to develop delivery vectors that can mitigate cell death and support integration. Lastly, host immune responses to allogeneic grafts must be thoroughly characterized and further developed to reduce the need for immunosuppression. Translation to a clinical setting will involve careful consideration when assessing both physiologic and functional outcomes. This review will highlight both successes and challenges faced when using human induced pluripotent stem cell-derived cell transplantation therapies to promote endogenous regeneration.

The paradigm shifts of periodontal regeneration strategy: From reparative manipulation to developmental engineering

Ideal periodontal regeneration requires the integration of alveolar bone, periodontal ligament, and cementum, along with Sharpey's fibers for occlusal force resistance. However, physiological regeneration remains rare due to its intricate structure, making clinical regeneration a challenge. Periodontal ligament stem cells (PDLSCs), first isolated in 2004, hold the key to multi-directional differentiation into cementoblasts, fibroblasts, and osteoblasts. While traditional therapies like guided tissue regeneration (GTR) aim to activate PDLSCs, clinical outcomes are inconsistent, suggesting the need for additional strategies to enhance PDLSCs' functions. Advancements in molecular biotechnology have introduced the use of recombinant growth factors for tissue regeneration. However, maintaining their efficacy requires high doses, posing cost and safety issues. Multi-layered scaffolds combined with cell sheet technology offer new insights, but face production, ethical, and survival challenges. Immune regulation plays a crucial role in PDLSC-mediated regeneration. The concept of "coagulo-immunomodulation" has emerged, emphasizing the coupling of blood coagulation and immune responses for periodontal regeneration. Despite its potential, the clinical translation of immune-based strategies remains elusive. The "developmental engineering" approach, which mimics developmental events using embryonic-stage cells and microenvironments, shows promise. Our research group has made initial strides, indicating its potential as a viable solution for periodontal complex regeneration. However, further clinical trials and considerations are needed for successful clinical application. This review aims to summarize the strategic transitions in the development of periodontal regenerative materials and to propose prospective avenues for future development.

Distinct anticancer properties of exosomes from induced mesenchymal stem cells vs. bone marrow-derived stem cells in MCF7 and A549 models

Mesenchymal stem cells (MSCs) have significant potential in regenerative medicine due to their multipotency, however, they face clinical challenges such as limited expansion and heterogeneity. Induced pluripotent stem cell-derived MSCs (iMSCs) are promising alternatives. The present study compared the effects of exosomes from bone marrow stromal MSCs (BMSCs) and iMSCs on A549 and MCF7 cancer cells to explore the unique properties of iMSCs. Proliferation assays revealed that both exosome types inhibited MCF7 and A549 cell proliferation at 24 h (P≤0.0001 for both) compared with the control, with BMSC-exosomes (Exos) exerting a more significant effect on MCF7 cells (P≤0.01). After 48 h, the significant effects of the BMSC-Exos were no longer observed on either cell line, whereas the iMSC-Exos continued to suppress A549 cell proliferation (P≤0.001 compared with the control; P≤0.01 compared with BMSC-Exos), indicating a longer-lasting effect. An investigation of senescence-associated β-galactosidase (SA-βGal) activity revealed no significant effect on senescence induction in MCF7 cells treated with either type of exosomes. By contrast, compared with the control treatment, the treatment of A549 cells with exosomes resulted in a significant increase in the number of senescent cells (P≤0.0001). While the apoptosis assay performed by flow cytometry revealed no significant effect on apoptosis, this increase in senescence aligned with the decreased proliferation observed in A549 cells, indicating that the antitumor effect of the exosomes on A549 cells was mediated partially through the induction of senescence. Wound healing assays revealed that BMSC-Exos significantly increased the migration of MCF7 cells at 20 h (P≤0.01). However, this effect was reversed at 47 h (P≤0.05), indicating a time-dependent effect of BMSC-Exos. In A549 cells, no significant difference in migration was observed after treatment with either exosome preparation. These findings highlight the distinct effects of iMSC- and BMSC-derived exosomes on cancer cells, emphasizing the need for further investigations into their therapeutic potential and underlying mechanisms.

A new dawn: Vitalising translational oncology research in Africa with the help of advanced cell culture models

The advent of in vitro models such as induced pluripotent stem cells (iPSC) and patient derived (disease) organoids is supporting the development of population and patient specific model systems reflecting human physiology and disease. However, there remains a significant underrepresentation of non-European, especially African model systems. The development of such models should be enthusiastically embraced by Sub-Saharan African countries (SSAC) and middle-income countries (LIMC) to direct their own research focused on the improvement of health of their own populations at a sustainable cost within their respective funding environments. Great care needs to be taken to develop national frameworks to direct, sustainably fund and support such efforts in a way that maximises the output of such models for the investment required. Here, we highlight how advanced culture models can play a role in vitalising local healthcare research by focusing on locally relevant health care questions using appropriate cell culture models. We also provide a potential national platform example that could maximise such output at the lowest cost. This framework presents an opportunity for SSAC and LMIC to base their healthcare research on locally relevant models to ensure that developed health care initiatives and interventions are best suited for the populations they serve and thus represent a reset in global health care research at large.

Microfluidic and Computational Tools for Neurodegeneration Studies

Understanding the molecular, cellular, and physiological components of neurodegenerative diseases (NDs) is paramount for developing accurate diagnostics and efficacious therapies. However, the complexity of ND pathology and the limitations associated with conventional analytical methods undermine research. Fortunately, microfluidic technology can facilitate discoveries through improved biomarker quantification, brain organoid culture, and small animal model manipulation. Because this technology can increase experimental throughput and the number of metrics that can be studied in concert, it demands more sophisticated computational tools to process and analyze results. Advanced analytical algorithms and machine learning platforms can address this challenge in data generated from microfluidic systems, but they can also be used outside of devices to discern patterns in genomic, proteomic, anatomical, and cognitive data sets. We discuss these approaches and their potential to expedite research discoveries and improve clinical outcomes through ND characterization, diagnosis, and treatment platforms.

Mammalian Blastema: Possibility and Potentials

Regeneration is a process that restores the structure and function of injured tissues or organs. Regenerative capacities vary significantly across species, with amphibians and fish demonstrating a high regenerative capacity even after severe injuries. This capacity is largely attributed to the formation of a blastema, a mass of multipotent cells reprogrammed from differentiated cells at the injury site. In contrast, mammals exhibit limited regenerative capacities, with blastema- like cells forming only in specific contexts, such as antler or digit tip regeneration. An interesting aspect of blastema formation in highly regenerative organisms is the temporary expression of pluripotency factors as known as the Yamanaka factors (YFs), which is a key requirement for reprogramming somatic cells into induced pluripotent stem cells (iPSCs). While iPSCs hold pros and cons, direct or partial reprogramming with YF has been proposed as a safer alternative. Since blastema formation and partial reprogramming are similar in terms of YF expressions, we found blastema-like cells in mammalian reprogramming with YF. This review outlines the characteristics of blastema across various organisms, emphasizing interspecies differences. We also explore studies on partial reprogramming and the possibility of inducing blastema-like cells via the temporary expression of YF in mammals.

Generation of Neural Organoids and Their Application in Disease Modeling and Regenerative Medicine

The complexity and precision of the human nervous system have posed significant challenges for researchers seeking suitable models to elucidate refractory neural disorders. Traditional approaches, including monolayer cell cultures and animal models, often fail to replicate the intricacies of human neural tissue. The advent of organoid technology derived from stem cells has addressed many of these limitations, providing highly representative platforms for studying the structure and function of the human embryonic brain and spinal cord. Researchers have induced neural organoids with regional characteristics by mimicking morphogen gradients in neural development. Recent advancements have demonstrated the utility of neural organoids in disease modeling, offering insights into the pathophysiology of various neural disorders, as well as in the field of neural regeneration. Developmental defects in neural organoids due to the lack of microglia or vascular systems are addressed. In addition to induction methods, microfluidics is used to simulate the dynamic physiological environment; bio-manufacturing technologies are employed to regulate physical signaling and shape the structure of complex organs. These technologies further expand the construction strategies and application scope of neural organoids. With the emergence of new material paradigms and advances in AI, new possibilities in the realm of neural organoids are witnessed.

Engineering the Future of Regenerative Medicines in Gut Health with Stem Cell-Derived Intestinal Organoids

The advent of intestinal organoids, three-dimensional structures derived from stem cells, has significantly advanced the field of biology by providing robust in vitro models that closely mimic the architecture and functionality of the human intestine. These organoids, generated from induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), or adult stem cells, possess remarkable capabilities for self-renewal, differentiation into diverse intestinal cell types, and functional recapitulation of physiological processes, including nutrient absorption, epithelial barrier integrity, and host-microbe interactions. The utility of intestinal organoids has been extensively demonstrated in disease modeling, drug screening, and personalized medicine. Notable examples include iPSC-derived organoids, which have been effectively employed to model enteric infections, and ESC-derived organoids, which have provided critical insights into fetal intestinal development. Patient-derived organoids have emerged as powerful tools for investigating personalized therapeutics and regenerative interventions for conditions such as inflammatory bowel disease (IBD), cystic fibrosis, and colorectal cancer. Preclinical studies involving transplantation of human intestinal organoids into murine models have shown promising outcomes, including functional integration, epithelial restoration, and immune system interactions. Despite these advancements, several challenges persist, particularly in achieving reproducibility, scalability, and maturation of organoids, which hinder their widespread clinical translation. Addressing these limitations requires the establishment of standardized protocols for organoid generation, culture, storage, and analysis to ensure reproducibility and comparability of findings across studies. Nevertheless, intestinal organoids hold immense promise for transforming our understanding of gastrointestinal pathophysiology, enhancing drug development pipelines, and advancing personalized medicine. By bridging the gap between preclinical research and clinical applications, these organoids represent a paradigm shift in the exploration of novel therapeutic strategies and the investigation of gut-associated diseases.

Induction of feline fetal fibroblasts into pluripotent stem cells using cat-derived reprogramming factors

There are few studies on the establishment of induced pluripotent stem cells (iPSCs) in cats. Although induction using heterologous reprogramming factors delivered via viral vectors has been reported, its safety and reprogramming efficiency still require improvement. In addition, the reprogramming mechanism needs further elucidation. In this study, we constructed a series of expression vectors for cat-derived reprogramming transcription factors based on the piggyBac transposon system and transfected various factor combinations into cat fetal fibroblasts (CFFs) under different electroporation conditions to generate cat iPSCs (ciPSCs). Additionally, the specific roles of these factors in reprogramming were investigated. The results showed that under the optimized electroporation conditions (DMEM/F12 buffer, 300 V, 10 ms pulse duration, 2 pulses, 25 μg plasmid DNA, and 4 mm cuvette), the survival rate and transfection efficiency of CFFs reached 64 % and 67.8 %, respectively. Based on this condition, a seven-factor combination (cOSKM + pNL + SV40 Large T) was confirmed as a better inducer for establishing ciPSCs. The obtained ciPSCs exhibit good pluripotency and passaging stability. They express stemness-related genes and proteins, and can form embryoid bodies (EBs) capable of differentiating into all three germ layers. OCT4 (O), SOX2 (S), KLF4 (K), and c-MYC (M) play important cooperative and synergistic roles in the mesenchymal-to-epithelial transition (MET) during the initial stages of reprogramming, while the supplement of NANOG (N) and LIN28 (L) can further promote MET and is important for successful reprogramming. It lays a foundation for the further breeding of cloned and genetically modified cats, and provides a tool for studying embryonic developmental diseases, screening drugs, and applying to tissue regeneration.

The Role of Oligodendrocytes in Neurodegenerative Diseases: Unwrapping the Layers

Neurodegenerative diseases (NDs), including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis/motor neuron disease, and multiple sclerosis, are characterized by progressive loss of neuronal structure and function, leading to severe cognitive, motor, and behavioral impairments. They pose a significant and growing challenge due to their rising prevalence and impact on global health systems. The societal and emotional toll on patients, caregivers, and healthcare infrastructures is considerable. While significant progress has been made in elucidating the pathological hallmarks of these disorders, the underlying cellular and molecular mechanisms remain incompletely understood. Increasing evidence implicates oligodendrocytes and their progenitors-oligodendrocyte progenitor cells (OPCs)-in the pathogenesis of several NDs, beyond their traditionally recognized role in demyelinating conditions such as MS. Oligodendrocytes are essential for axonal myelination, metabolic support, and neural circuit modulation in the central nervous system. Disruptions in oligodendrocyte function and myelin integrity-manifesting as demyelination, hypomyelination, or dysmyelination-have been associated with disease progression in various neurodegenerative contexts. This review consolidates recent findings on the role of OPCs in NDs, explores the concept of myelin plasticity, and discusses therapeutic strategies targeting oligodendrocyte dysfunction. By highlighting emerging research in oligodendrocyte biology, this review aims to provide a short overview of its relevance to neurodegenerative disease progression and potential therapeutic advances.

In silico modelling of multi-electrode arrays for enhancing cardiac drug testing on hiPSC-CM heterogeneous tissues

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) offer a transformative platform for in vitro and in silico testing of patient-specific drugs, enabling detailed study of cardiac electrophysiology. By integrating standard experimental techniques with extracellular potential measurements from multi-electrode arrays (MEAs), researchers can capture key tissue-level electrophysiological properties, such as action potential dynamics and conduction characteristics. This study presents an innovative computational framework that combines an MEA-based electrophysiological model with phenotype-specific hiPSC-CM ionic models, enabling accurate in silico predictions of drug responses. We tested four drug compounds and ion channel blockers using this model and compared these predictions against experimental MEA data, establishing the model's robustness and reliability. Additionally, we examined how tissue heterogeneity in hiPSC-CMs affects conduction velocity, providing insights into how cellular variations can influence drug efficacy and tissue-level electrical behaviour. Our model was further tested through simulations of Brugada syndrome, successfully replicating pathological electrophysiological patterns observed in adult cardiac tissues. These findings highlight the potential of hiPSC-CM MEA-based in silico modelling for advancing drug screening processes, which have the potential to refine disease-specific therapy development, and improve patient outcomes in complex cardiac conditions. KEY POINTS: Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) offer a transformative platform for in vitro and in silico testing of patient-specific drugs, enabling detailed study of cardiac electrophysiology. Development of an innovative computational framework that combines a multi-electrode array (MEA)-based electrophysiological model with phenotype-specific hiPSC-CM ionic models. Drug testing of four compounds and ion channel blockers using this hiPSC-CM MEA model and comparison against experimental MEA data, establishing the model's robustness and reliability. Study of the effect of tissue heterogeneity in hiPSC-CMs on conduction velocity, providing insights into how cellular variations can influence drug efficacy and tissue-level electrical behaviour. Brugada syndrome simulation through the hiPSC-CM MEA model, successfully replicating pathological electrophysiological patterns observed in adult cardiac tissues.

Tracing mitochondrial marks of neuronal aging in iPSCs-derived neurons and directly converted neurons

This study aims to determine if neurons derived from induced pluripotent stem cells (iPSCsNs) and directly converted neurons (iNs) from the same source cells exhibit changes in mitochondrial properties related to aging. This research addresses the uncertainty around whether aged iPSCsNs retain aging-associated mitochondrial impairments upon transitioning through pluripotency while direct conversion maintains these impairments. We observe that both aged models exhibit characteristics of aging, such as decreased ATP, mitochondrial membrane potential, respiration, NAD+/NADH ratio, and increased radicals and mitochondrial mass. In addition, both neuronal models show a fragmented mitochondrial network. However, aged iPSCsNs do not exhibit a metabolic shift towards glycolysis, unlike aged iNs. Furthermore, mRNA expression differed significantly between aged iPSCsNs and aged iNs. The study concludes that aged iPSCsNs may differ in transcriptomics and the aging-associated glycolytic shift but can be a valuable tool for studying specific feature of mitochondrial neuronal aging in vitro alongside aged iNs.

Targeting Muscle Regeneration with Small Extracellular Vesicles from Adipose Tissue-Derived Stem Cells-A Review

Extracellular vesicles (EVs) are membrane-bound structures released by cells carrying diverse biomolecules involved in intercellular communication. Small EVs are abundant in body fluids, playing a key role in cell signaling. Their natural occurrence and therapeutic potential, especially in the context of muscular disorders, make them a significant area of research. Sarcopenia, characterized by progressive muscle fiber loss, represents a pathological state in which EVs could offer therapeutic benefits, reducing morbidity and mortality. Recent studies have proposed an interplay between adipose tissue (AT) and skeletal muscle regarding sarcopenia pathology. AT dysregulation, as seen in obesity, contributes to skeletal muscle loss in a multifactorial way. While AT-derived stem cell (ATDSC) small EVs have been implicated in musculoskeletal homeostasis, their precise action in muscle regeneration remains incompletely understood. In this context, ATDSC-derived small EVs can stimulate skeletal muscle regeneration through improved proliferation and migration of muscle cells, enhancement of muscular perfusion, improvement of tendon and nerve regeneration, stimulation of angiogenesis, and promotion of myogenic differentiation. However, they can also increase skeletal muscle loss. Notably, this is the first comprehensive review to systematically examine the role of ATDSC-derived small EVs in sarcopenia.

Repair mechanisms of the central nervous system: From axon sprouting to remyelination

The central nervous system (CNS), comprising the brain, spinal cord, and optic nerve, has limited regenerative capacity, posing significant challenges in treating neurological disorders. Recent advances in neuroscience and neurotherapeutics have introduced promising strategies to stimulate CNS repair, particularly in the context of neurodegenerative diseases such as multiple sclerosis. This review explores the complex interplay between inflammation, demyelination, and remyelination possibilities. Glial cells, including oligodendrocyte precursors, oligodendrocytes, astrocytes and microglia play dual roles in injury response, with reactive gliosis promoting repair but also potentially inhibiting recovery through glial scar formation. There is also an emphasis on axonal regeneration, axonal sprouting and stem cell therapies. We highlight the role of neuroplasticity in recovery post-injury and the limited regenerative potential of axons in the CNS due to inhibitory factors such as myelin-associated inhibitors. Moreover, neurotrophic factors support neuronal survival and axonal growth, while stem cell-based approaches offer promise for replacing lost neurons and glial cells. However, challenges such as stem cell survival, integration, and risk of tumor formation remain. Furthermore, we examine the role of neurogenesis in CNS repair and the remodeling of the extracellular matrix, which can facilitate regeneration. Through these diverse mechanisms, ongoing research aims to overcome the intrinsic and extrinsic barriers to CNS repair and advance therapeutic strategies for neurological diseases.

A comprehensive analysis of induced pluripotent stem cell (iPSC) production and applications

The ability to reprogram mature, differentiated cells into induced pluripotent stem cells (iPSCs) using exogenous pluripotency factors opened up unprecedented opportunities for their application in biomedicine. iPSCs are already successfully used in cell and regenerative therapy, as various drug discovery platforms and for in vitro disease modeling. However, even though already 20 years have passed since their discovery, the production of iPSC-based therapies is still associated with a number of hurdles due to low reprogramming efficiency, the complexity of accurate characterization of the resulting colonies, and the concerns associated with the safety of this approach. However, significant progress in many areas of molecular biology facilitated the production, characterization, and thorough assessment of the safety profile of iPSCs. The number of iPSC-based studies has been steadily increasing in recent years, leading to the accumulation of significant knowledge in this area. In this review, we aimed to provide a comprehensive analysis of methods used for reprogramming and subsequent characterization of iPSCs, discussed barriers towards achieving these goals, and various approaches to improve the efficiency of reprogramming of different cell populations. In addition, we focused on the analysis of iPSC application in preclinical and clinical studies. The accumulated breadth of data helps to draw conclusions about the future of this technology in biomedicine.

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.

Human stromal cell-based protocol to generate astrocytes: a straightforward in vitro predictive strategy in neurotoxicology

The inherent adaptability of human mesenchymal stromal cells (hMSCs) to differentiate into neural lineages provides a valuable resource for investigating potential neurotoxicity in humans. By harnessing the ability of hMSCs to transform into astrocytes, we can evaluate the effects of various agents on these vital cells. Our protocol employs hMSCs sourced from umbilical cord tissue, ensuring a readily available supply of high-quality cells. The hMSC-to-neural workflow encompasses six essential steps: hMSC culture, followed by the generation of embryoid bodies (EBs) from these cells on specialized surfaces. Next, EBs and cells are expanded in a growth-promoting medium, directing them toward neural lineages. Subsequent differentiation into immature astrocytes is achieved through the use of specific factors. The process continues with the maturation of EBs/cells into astrocyte-like cells (hALCs) under optimized conditions, culminating in the final development of hALCs in a specialized medium. This methodology yields cells that display astrocyte morphology and express characteristic markers such as GFAP and S100β. The protocol is efficient, requiring roughly 6 weeks to generate hALCs from primary hMSCs without genetic manipulation. The application of hMSCs in evaluating cell damage triggered by neurotoxicants like MeHg and MGO underscores their potential as a valuable component within a more extensive battery of neurotoxicity tests.

Cell Therapy and the Skin: Great Potential but in Need of Optimization

Cell therapy is rapidly growing owing to its therapeutic potential for diseases with currently poor outcomes. Cell therapy encompasses both nonengineered and engineered cells and possesses unique abilities such as sense-and-respond functions and long-term engraftment for persistent curative potential. Cell therapy capabilities have expanded to address a wide spectrum of diseases, and our review is focused on dermatological applications. The use of fibroblasts and keratinocytes as cell therapy has shown promise in skin disorders such as epidermolysis bullosa. Future efforts include testing the ability of fibroblasts to reprogram nonvolar to volar skin to reduce stump dermatoses in patients with limb loss using prosthetics.

Chemical-based epigenetic reprogramming to advance pluripotency and totipotency

Reprogramming technology, breaking the inherent limitations of cellular identity and turning somatic cells into pluripotent cells with more developmental potential, holds great promise for cell therapy and regenerative medicine. Compared with traditional methods based on overexpressing transcription factors, chemical reprogramming with small molecules exhibits substantial advantages in safety and convenience, thus being the leading edge. Over the past decade, a notable focus has been reshaping cellular pluripotency and totipotency using pure small-molecule systems. Here, we provide a concise Review comparing the chemical approaches that have emerged to date and discussing the epigenetic regulatory mechanisms involved in chemical reprogramming. This Review highlights the remarkable potential of small-molecule potions to reformulate cell fate through epigenetic reprogramming and newly discovered actions. We aim to offer insights into chemically controlled cell manipulation and key challenges and future application prospects of chemical reprogramming.

Induced Pluripotent Stem Cells-Based Regenerative Therapies in Treating Human Aging-Related Functional Decline and Diseases

A significant increase in life expectancy worldwide has resulted in a growing aging population, accompanied by a rise in aging-related diseases that pose substantial societal, economic, and medical challenges. This trend has prompted extensive efforts within many scientific and medical communities to develop and enhance therapies aimed at delaying aging processes, mitigating aging-related functional decline, and addressing aging-associated diseases to extend health span. Research in aging biology has focused on unraveling various biochemical and genetic pathways contributing to aging-related changes, including genomic instability, telomere shortening, and cellular senescence. The advent of induced pluripotent stem cells (iPSCs), derived through reprogramming human somatic cells, has revolutionized disease modeling and understanding in humans by addressing the limitations of conventional animal models and primary human cells. iPSCs offer significant advantages over other pluripotent stem cells, such as embryonic stem cells, as they can be obtained without the need for embryo destruction and are not restricted by the availability of healthy donors or patients. These attributes position iPSC technology as a promising avenue for modeling and deciphering mechanisms that underlie aging and associated diseases, as well as for studying drug effects. Moreover, iPSCs exhibit remarkable versatility in differentiating into diverse cell types, making them a promising tool for personalized regenerative therapies aimed at replacing aged or damaged cells with healthy, functional equivalents. This review explores the breadth of research in iPSC-based regenerative therapies and their potential applications in addressing a spectrum of aging-related conditions.

Establishment of a Human iPSC Line from Mucolipidosis Type II That Expresses the Key Markers of the Disease

Mucolipidosis type II (ML II) is a rare and fatal disease of acid hydrolase trafficking. It is caused by pathogenic variants in the GNPTAB gene, leading to the absence of GlcNAc-1-phosphotransferase activity, an enzyme that catalyzes the first step in the formation of the mannose 6-phosphate (M6P) tag, essential for the trafficking of most lysosomal hydrolases. Without M6P, these do not reach the lysosome, which accumulates undegraded substrates. The lack of samples and adequate disease models limits the investigation into the pathophysiological mechanisms of the disease and potential therapies. Here, we report the generation and characterization of an ML II induced pluripotent stem cell (iPSC) line carrying the most frequent ML II pathogenic variant [NM_024312.5(GNPTAB):c.3503_3504del (p.Leu1168fs)]. Skin fibroblasts were successfully reprogrammed into iPSCs that express pluripotency markers, maintain a normal karyotype, and can differentiate into the three germ layers. Furthermore, ML II iPSCs showed a phenotype comparable to that of the somatic cells that originated them in terms of key ML II hallmarks: lower enzymatic activity of M6P-dependent hydrolases inside the cells but higher in conditioned media, and no differences in an M6P-independent hydrolase and accumulation of free cholesterol. Thus, ML II iPSCs constitute a novel model for ML II disease, with the inherent iPSC potential to become a valuable model for future studies on the pathogenic mechanisms and testing potential therapeutic approaches.

Clinical characteristics and induced pluripotent stem cells (iPSCs) disease model of Harel-Yoon syndrome caused by compound heterozygous ATAD3A variants

ATPase family AAA-domain-containing protein 3 A (ATAD3A) is enriched on the mitochondrial membrane and is essential to the maintenance of mitochondrial structure and function. Variants of the ATAD3A gene can lead to Harel-Yoon syndrome (HAYOS), a developmental defect in neurological, cardiovascular, and other systems. This study aims to develop induced pluripotent stem cells (iPSCs) from the somatic cells of a patient (ZJUCHYLi001-A) and a negative control (ZJUCHYLi002-A) as effective tools for further investigations into the etiology of ATAD3A variant-related disease. We described and analyzed the clinical manifestations of the proband and her family members. Somatic cells from the proband and a negative control were collected and reprogrammed into iPSCs. Furthermore, we measured the ATAD3A expression levels in the iPSCs to confirm the validity of these cell lines. The proband and her elder sister were both critically ill and harbored compound heterozygous ATAD3A variants (F459S/T498 Nfs* 13). Their parents were carriers of these variants without any clinical manifestations. Both variants are located on the ATPase domain of the ATAD3A protein. Cell lines ZJUCHYLi001-A and ZJUCHYLi002-A presented typical features of pluripotent stem cells. The ATAD3A expression levels of ZJUCHYLi001-A were significantly reduced compared with ZJUCHYLi002-A. This study generated iPSCs from a patient with compound heterozygous variants of ATAD3A and a negative control as valuable tools for clarifying the molecular mechanisms underlying ATAD3A variant-related diseases.

Current Development of iPSC-Based Modeling in Neurodegenerative Diseases

Over the past two decades, significant advancements have been made in the induced pluripotent stem cell (iPSC) technology. These developments have enabled the broader application of iPSCs in neuroscience, improved our understanding of disease pathogenesis, and advanced the investigation of therapeutic targets and methods. Specifically, optimizations in reprogramming protocols, coupled with improved neuronal differentiation and maturation techniques, have greatly facilitated the generation of iPSC-derived neural cells. The integration of the cerebral organoid technology and CRISPR/Cas9 genome editing has further propelled the application of iPSCs in neurodegenerative diseases to a new stage. Patient-derived or CRISPR-edited cerebral neurons and organoids now serve as ideal disease models, contributing to our understanding of disease pathophysiology and identifying novel therapeutic targets and candidates. In this review, we examine the development of iPSC-based models in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease.

Development of regenerative therapies targeting fibrotic endometrium in intrauterine adhesion or thin endometrium to restore uterine function

Intrauterine adhesions (IUA) and thin endometrium (TE) represent significant challenges in human reproduction. The condition arises frequently from damage to the endometrial basal layer, leading to fibrous tissue replacing the functional endometrium and impairing the uterus's ability to accept embryo implantation. Conventional treatments, mainly including hysteroscopic adhesiolysis and estrogen therapies, have shown limited success, particularly in severe cases. Regenerative medicine, with its focus on stem cell-based therapies and biomaterials, offers a promising avenue for restoring endometrial function and structure. This review synthesizes the current landscape of endometrial regeneration, focusing on the therapeutic potential of stem cells, the supportive role of biomaterials, and the importance of understanding molecular mechanisms to develop effective strategies for reconstruction of endometrial functional and fertility restoration.

Induced Pluripotent Stem Cells in Congenital Long QT Syndrome: Research Progress and Clinical Applications

Congenital long QT syndrome (LQTS) is a potentially life-threatening hereditary arrhythmia characterized by a prolonged QT interval on electrocardiogram (ECG) due to delayed ventricular repolarization. This condition predisposes individuals to severe arrhythmic events, including ventricular tachycardia and sudden cardiac death. Traditional approaches to LQTS research and treatment are limited by an incomplete understanding of its gene-specific pathophysiology, variable clinical presentation, and the challenges associated with developing effective, personalized therapies. Recent advances in human induced pluripotent stem cell (iPSC) technology have opened new avenues for elucidating LQTS mechanisms and testing therapeutic strategies. By generating cardiomyocytes from patient-specific iPSCs (iPSC-CMs), it is now possible to recreate the patient's genetic context and study LQTS in a controlled environment. This comprehensive review describes how iPSC technology deepens our understanding of LQTS and accelerates the development of tailored treatments, as well as ongoing challenges such as incomplete cell maturation and cellular heterogeneity.

Isogenic induced pluripotent stem cell line ICGi036-A-1 from a patient with familial hypercholesterolaemia, derived by correcting a pathogenic variant of the gene LDLR c.530C>T

Familial hypercholesterolaemia is a common monogenic disorder characterized by high plasma cholesterol levels leading to chronic cardiovascular disease with high risk and often early manifestation due to atherosclerotic lesions of the blood vessels. The atherosclerotic lesions in familial hypercholesterolaemia are mainly caused by pathogenic variants of the low-density lipoprotein receptor (LDLR) gene, which plays an important role in cholesterol metabolism. Normally, cholesterol-laden low-density lipoproteins bind to the LDLR receptor on the surface of liver cells to be removed from the bloodstream by internalisation with hepatocytes. In familial hypercholesterolaemia, the function of the receptor is impaired and the uptake of low-density lipoproteins is significantly reduced. As a result, cholesterol accumulates in the subendothelial space on the inner wall of blood vessels, triggering atherogenesis, the formation of atherosclerotic plaques. At present, there are no effective and universal approaches to the diagnosis and treatment of familial hypercholesterolaemia. A relevant approach to study the molecular genetic mechanisms of the disease and to obtain systems for screening chemical compounds as potential drugs is the generation of cellular models based on patient-specific induced pluripotent stem cells. The aim of our work was to derive an isogenic genetically modified induced pluripotent stem cell line by correcting the pathogenic allelic variant c.530C of the LDLR gene in the original iPSC previously obtained from a compound heterozygote patient with familial hypercholesterolaemia. The resulting isogenic iPSC line differs from the original by only one corrected nucleotide substitution, allowing us to study the direct effect of this pathogenic genetic variant on physiological changes in relevant differentiated cells. CRISPR/Cas-mediated base editing was used to correct the single nucleotide substitution. The resulting genetically modified iPSC line has pluripotency traits, a normal karyotype, a set of short tandem repeats identical to that in the original line and can be used to obtain differentiated derivatives necessary for the elaboration of relevant cell models.

The novel combination of small-molecule inhibitors increases the survival and colony formation capacity of human induced pluripotent stem cells after single-cell dissociation

ObjectivesHuman induced pluripotent stem cells (hiPSCs) hold significant promise in regenerative medicine and drug discovery. However, single-cell dissociation, essential for genetic modification and clonal selection, often reduces hiPSC viability and colony formation. While various methods, including small molecules and feeder cells, have been developed to address this, their outcomes remain inconsistent. This study aims to develop more efficient methods to enhance hiPSC survival post-dissociation using a novel combination of well-characterized small-molecule inhibitors.MethodsHuman induced pluripotent stem cells were pretreated with Rho-associated protein kinase inhibitor (Y27632), SMC4 (PD0325901 + CHIR99021 + thiazovivin + SB431542), or SiM5 (PD0325901 + CHIR99021 + Thiazovivin + SB431542 + Pifithrin-α) for 1 h before subjected to single-cell dissociation by accutase. The dissociated single hiPSCs were then cultured in NutriStem or StemFlex medium supplemented with Y27632, SMC4, or SiM5. Cell viability, pluripotency marker expression, colony formation capacity, and karyotype were then compared between various treatments. The effect of SiM5 treatment on hiPSCs survival and colony formation capacity was also tested under hypoxic conditions and after fluorescence-activated cell sorting.ResultsThe results show that SiM5 treatment significantly increases hiPSCs survival by approximately 2.5 and 25 times compared to those treated with SMC4 and Y27632, respectively. These results were consistently observed across different cell lines and culture media. Furthermore, SiM5 treatment also increased hiPSCs survival and proliferation after single-cell dissociation under hypoxic conditions. The withdrawal of SiM5 after treatment only temporarily hinders hiPSCs cell cycle progression, without impairing their subsequent expansion. Fluorescence-activated cell sorting analysis revealed that SiM5 does not affect the pluripotency of hiPSCs following treatment. Additionally, it was found that SiM5 has no effect on the colony-forming ability or chromosomal stability of hiPSCs.ConclusionSiM5 treatment significantly improves hiPSCs survival and colony formation after single-cell dissociation across various conditions. This approach could enhance the efficiency of genetic manipulation and single-cell cloning, advancing hiPSCs applications in research and clinical settings.

3D Bioprinted Coaxial Testis Model Using Human Induced Pluripotent Stem Cells:A Step Toward Bicompartmental Cytoarchitecture and Functionalization

Fertility preservation following pediatric cancer therapy programs has become a major avenue of infertility research. In vitro spermatogenesis (IVS) aims to generate sperm from banked prepubertal testicular tissues in a lab setting using specialized culture conditions. While successful using rodent tissues, progress with human tissues is limited by the scarcity of human prepubertal testicular tissues for research. This study posits that human induced pluripotent stem cells (hiPSCs) can model human prepubertal testicular tissue to facilitate the development of human IVS conditions. Testicular cells derived from hiPSCs are characterized for phenotype markers and profiled transcriptionally. HiPSC-derived testicular cells are bioprinted into core-shell constructs representative of testis cytoarchitecture and found to capture functional aspects of prepubertal testicular tissues within 7 days under xeno-free conditions. Moreover, hiPSC-derived Sertoli cells illustrate the capacity to mature under pubertal-like conditions. The utility of the model is tested by comparing 2 methods of supplementing retinoic acid (RA), the vitamin responsible for inducing spermatogenesis. The model reveals a significant gain in activity under microsphere-released RA compared to RA medium supplementation, indicating that the fragility of free RA in vitro may be a contributing factor to the molecular dysfunction observed in human IVS studies to date.

Cell reprogramming: methods, mechanisms and applications

Cell reprogramming represents a powerful approach to achieve the conversion cells of one type into cells of another type of interest, which has substantially changed the landscape in the field of developmental biology, regenerative medicine, disease modeling, drug discovery and cancer immunotherapy. Cell reprogramming is a complex and ordered process that involves the coordination of transcriptional, epigenetic, translational and metabolic changes. Over the past two decades, a range of questions regarding the facilitators/barriers, the trajectories, and the mechanisms of cell reprogramming have been extensively investigated. This review summarizes the recent advances in cell reprogramming mediated by transcription factors or chemical molecules, followed by elaborating on the important roles of biophysical cues in cell reprogramming. Additionally, this review will detail our current understanding of the mechanisms that govern cell reprogramming, including the involvement of the recently discovered biomolecular condensates. Finally, the review discusses the broad applications and future directions of cell reprogramming in developmental biology, disease modeling, drug development, regenerative/rejuvenation therapy, and cancer immunotherapy.

Bone Defect Treatment in Regenerative Medicine: Exploring Natural and Synthetic Bone Substitutes

In recent years, the management of bone defects in regenerative medicine and orthopedic surgery has been the subject of extensive research efforts. The complexity of fractures and bone loss arising from trauma, degenerative conditions, or congenital disorders necessitates innovative therapeutic strategies to promote effective healing. Although bone tissue exhibits an intrinsic regenerative capacity, extensive fractures and critical-sized defects can severely compromise this process, often requiring bone grafts or substitutes. Tissue engineering approaches within regenerative medicine have introduced novel possibilities for addressing nonunions and challenging bone defects refractory to conventional treatment methods. Key components in this field include stem cells, bioactive growth factors, and biocompatible scaffolds, with a strong focus on advancements in bone substitute materials. Both natural and synthetic substitutes present distinct characteristics and applications. Natural grafts-comprising autologous, allogeneic, and xenogeneic materials-offer biological advantages, while synthetic alternatives, including biodegradable and non-biodegradable biomaterials, provide structural versatility and reduced immunogenicity. This review provides a comprehensive analysis of the diverse bone grafting alternatives utilized in orthopedic surgery, emphasizing recent advancements and persistent challenges. By exploring both natural and synthetic bone substitutes, this work offers an in-depth examination of cutting-edge solutions, fostering further research and innovation in the treatment of complex bone defects.

Pluripotent Stem Cells: Recent Advances and Emerging Trends

The field of induced pluripotent stem cells (iPSCs) continues to evolve, offering unprecedented potential for regenerative medicine, disease modeling, and therapeutic applications [...].

5-Aza combined with VPA reprograms human T lineage acute leukemia Jurkat cells into B-cell-like cells by epigenetic activation of PAX5

Epigenetic regulation plays an important role in cell fate reprogramming. Here, we found that inhibitors of epigenetic modifiers, including VPA, TSA, and 5-Aza-2'-deoxycytidine, can induce phenotypic transformation from Jurkat cells into B-cell-like cells. When Jurkat cells were treated with 5-Aza combined with VPA, B cell and stem cell marker expression was observed. These gene expression pattern changes were most remarkable in the optimized B cell induction conditions provided by the cocultured and genetically modified murine bone marrow OP9 cells. In such conditions, Jurkat cells were endowed with the ability to secrete B cell cytokines, and B lymphocyte-related genes and pathways were activated. In studying the mechanism underlying Jurkat cell reprogramming by 5-Aza and VPA, we found that PAX5, the key transcription factor regulating B cell development, was significantly upregulated. Treatment with 5-Aza and VPA inhibited the methylation of CpG islands and upregulated the acetylated H3K9 modification in the PAX5 promoter region, respectively, thus epigenetically activating the expression of PAX5 and promoting the reprogramming of Jurkat cells. Similar reprogramming results were also observed in primary CD4+T cells following treatment with 5-Aza and VPA. Our results provide a de novo paradigm for the reprogramming of T cells through epigenetic modifications.

Hydrogen Peroxide-Releasing Hydrogel-Mediated Cellular Senescence Model for Aging Research

Cellular senescence, a process that induces irreversible cell cycle arrest in response to diverse stressors, is a primary contributor to aging and age-related diseases. Currently, exposure to hydrogen peroxide is a widely used technique for establishing in vitro cellular senescence models; however, this traditional method is inconsistent, laborious, and ineffective in vivo. To overcome these limitations, we have developed a hydrogen peroxide-releasing hydrogel that can readily and controllably induce senescence in conventional 2-dimensional cell cultures as well as advanced 3-dimensional microphysiological systems. Notably, we have established 2 platforms using our hydrogen peroxide-releasing hydrogel for investigating senolytics, which is a promising innovation in anti-geronic therapy. Conclusively, our advanced model presents a highly promising tool that offers a simple, versatile, convenient, effective, and highly adaptable technique for inducing cellular senescence. This innovation not only lays a crucial foundation for future research on aging but also markedly accelerates the development of novel therapeutic strategies targeting age-related diseases.

Efficient Differentiation of hiPSCs into hMSC-like Cells under Chemically Defined Conditions on Temperature-Sensitive Micropatterned Surfaces

The fairness of long-term self-renewal and robust cell proliferation limits the applications of human mesenchymal stem cells (hMSCs) in regenerative medicine. Inducing hMSCs from human-induced pluripotent stem cells (hiPSCs), which have the advantages of autogenous and no cell number issues, is highly valuable. However, current induction methods using FBS-containing mesenchymal culture medium have problems, including immunogenicity, microbial contamination, and low efficiency. To solve these problems, we propose a chemically defined induction protocol incorporating transforming growth factor-beta 1 and retinoic acid (RA) additives in serum-free E6 medium for the suspension induction of embryoid bodies in hiPSCs. Additionally, microgroove-patterned polydimethylsiloxane surfaces coated with temperature-sensitive N-isopropylacrylamide (PNIPAAm) were prepared for efficient harvesting and purification of induced hiPSC-derived hMSCs (hiPSC-MSCs). The results showed that both supplementation with RA and patterned microgrooves with a width of 20 μm could accelerate the induction of hiPSC-MSCs, realizing the promising scalable production of homogeneous cells. This study successfully established a chemically defined induction protocol and utilized patterned surfaces to obtain clinically applicable hiPSC-MSCs, which show great promise in tissue engineering, gene therapy, and cell transplantation.

Stem cell mechanoadaptation. II. Microtubule stabilization and substrate compliance effects on cytoskeletal remodeling

Stem cells adapt to their local mechanical environment by rearranging their cytoskeleton, which underpins the evolution of their shape and fate as well as the emergence of tissue structure and function. Here, in the second part of a two-part experimental series, we aimed to elucidate spatiotemporal cytoskeletal remodeling and resulting changes in morphology and mechanical properties of cells and their nuclei. Akin to mechanical testing of the most basic living and adapting unit of life, i.e., the cell, in situ in model tissue templates, we probed native and microtubule-stabilized (via Paclitaxel, PAX, exposure) stem cells' cytoskeletal adaptation capacity on substrates of increasing compliance (exerting local tension on cells) and with increased target seeding densities (exerting local compression on cells). On 10 and 100 kPa gels, cells seeded at 5000 cells/cm2 and cells proliferated to 15 000 cells/cm2 exhibited bulk moduli that nearly matched those of their respective substrates; hence, they exhibited a greater increase in Young's Modulus after microtubule stabilization than cells cultured on glass. Culture on compliant substrates also reduced microtubule-stabilized cells' F-actin, and microtubule concentration increases compared to cells seeded on glass. On gels, F-actin alignment decreased as more randomly oriented, short actin crosslinks were observed, representing emergent adaptation to the compliant substrate, mediated through myosin II contractility. We conclude that stem cell adaptation to compliant substrates facilitates the accommodation of larger loads from the PAX-stabilized polymerizing microtubule, which, in turn, exerts a larger effect in determining cells' capacity to stiffen and remodel the cytoskeleton. Taken as a whole, these studies establish correlations between cytoskeleton and physical and mechanical parameters of stem cells. Hence, the studies progress our understanding of the dynamic cytoskeleton as well as shape changes in cells and their nuclei, culminating in emergent tissue development and healing.

Functional regeneration strategies of hair follicles: advances and challenges

Hair follicles are essential appendages of human skin that function in protection, sensation, thermoregulation and social interactions. The multicellular components, particularly the dermal papilla, matrix and bulge housing stem cells, enable cyclic hair growth postnatally. However, miniaturization and loss of hair follicles can occur in the context of ageing, trauma and various alopecia-related diseases. Conventional treatments involve the redistribution of existing follicles, which may not be viable in patients lacking follicular resources. Recent progress in the comprehension of morphogenesis and the development of biomaterials has significantly advanced follicle reconstruction, incorporating organ germ assembling, stem cell induction and bioprinting techniques. Despite these advancements, fully restoring hair follicles remains challenging due to the complexities of replicating embryonic signals and sustaining growth cycles. Identifying suitable cell sources for clinical applications also presents a hurdle. Here, we retrospect the progress made in the field of hair follicle regeneration, aiming to offer an exhaustive analysis on the benefits and limitations of these methods, and to foster the development of innovative solutions.

20 years of ROBO3-related horizontal gaze palsy with progressive scoliosis: a mini-review

ROBO3 is a member of the Roundabout (ROBO) gene family of evolutionarily conserved guidance receptors, which plays crucial roles in axon crossing of the CNS midline. In 2004, pathogenic variants in ROBO3 were first linked to Horizontal Gaze Palsy with Progressive Scoliosis type 1 [HGPPS1 (OMIM # 607313)], an autosomal recessive disorder that is characterized by failure of the corticospinal and somatosensory axon tracts to decussate in the medulla. Hitherto, over 60 ROBO3 pathogenic (or likely pathogenic) variants associated with HGPPS1 have been described in almost 100 patients. With the 20-year milestone, this minireview underscores the growing opportunities to improve the current understanding of the spectrum of HGPPS1 phenotype and ROBO3 genotypes. The increasing need for translational studies that can pave the way for improved clinical management of ROBO3-related disorders is also highlighted.

Development and evaluation of siRNA-mediated gene silencing strategies for ADO2 therapy utilizing iPSCs model and DMPC-SPIONs delivery system

BACKGROUND

Autosomal dominant osteodystrophy type II (ADO2) is an inherited disease characterized by an abnormal increase in bone mineral density, and CLCN7 (R286W) is its most common causative mutation. The aim of this study was to explore the new idea of siRNA technology applied to the in vitro treatment of ADO2.

METHODS

Urinary-derived cells from ADO2 patients were collected to establish induced pluripotent stem cells (iPSCs) model. The siRNA targeting CLCN7 (R286W) mutant mRNA was designed. the cytotoxicity of the delivery vector DMPC-SPIONs was comprehensively evaluated by CCK-8 assay, flow cytometry and scratch assay. Finally, qPCR was utilized to verify the post-transcriptional silencing effect of siRNAs.

RESULTS

We found that DMPC-SPIONs had low cytotoxicity and were able to effectively deliver siRNAs into ADO2-iPSCs. qPCR confirmed that siRNA-DMPC-SPIONs were able to significantly reduce the expression level of mutant CLCN7 (66%), while there was no significant effect on the expression of wild-type CLCN7.

CONCLUSIONS

This study developed a gene silencing strategy based on siRNAs and DMPC-SPIONs, which provides a potential new approach for the treatment of ADO2 and demonstrates the potential application of siRNA technology in the treatment of autosomal dominant genetic diseases.

INNOVATIVE STATEMENTS

In this study, we used the established ADO2-iPSCs using patient's urine-derived cells to explore the safety and efficacy of siRNA technology based on the principle of RNA interference for ADO2 treatment for the first time. In addition, we chose DMPC-SPIONs as the delivery vehicle for siRNA, which cleverly exploits the advantages of nanoparticles such as superparamagnetism, low cytotoxicity, and good bio-histocompatibility.

Organoid models: applications and research advances in colorectal cancer

This review summarizes the applications and research progress of organoid models in colorectal cancer research. First, the high incidence and mortality rates of colorectal cancer are introduced, emphasizing the importance of organoids as a research model. Second, this review provides a detailed introduction to the concept, biological properties, and applications of organoids, including their strengths in mimicking the structural and functional aspects of organs. This article further analyzes the applications of adult stem cell-derived and pluripotent stem cell-derived organoids in colorectal cancer research and discusses advancements in organoids for basic research, drug research and development, personalized treatment evaluation and prediction, and regenerative medicine. Finally, this review summarizes the prospects for applying organoid technology in colorectal cancer research, emphasizing its significant value in improving patient survival rates. In conclusion, this review systematically explains the applications of organoids in colorectal cancer research, highlighting their tremendous potential and promising prospects in basic research, drug research and development, personalized treatment evaluation and prediction, and regenerative medicine.

Glial Cell Reprogramming in Ischemic Stroke: A Review of Recent Advancements and Translational Challenges

Ischemic stroke, the second leading cause of death worldwide and the leading cause of long-term disabilities, presents a significant global health challenge, particularly in aging populations where the risk and severity of cerebrovascular events are significantly increased. The aftermath of stroke involves neuronal loss in the infarct core and reactive astrocyte proliferation, disrupting the neurovascular unit, especially in aged brains. Restoring the balance between neurons and non-neuronal cells within the perilesional area is crucial for post-stroke recovery. The aged post-stroke brain mounts a fulminant proliferative astroglial response, leading to gliotic scarring that prevents neural regeneration. While countless therapeutic techniques have been attempted for decades with limited success, alternative strategies aim to transform inhibitory gliotic tissue into an environment conducive to neuronal regeneration and axonal growth through genetic conversion of astrocytes into neurons. This concept gained momentum following discoveries that in vivo direct lineage reprogramming in the adult mammalian brain is a feasible strategy for reprogramming non-neuronal cells into neurons, circumventing the need for cell transplantation. Recent advancements in glial cell reprogramming, including transcription factor-based methods with factors like NeuroD1, Ascl1, and Neurogenin2, as well as small molecule-induced reprogramming and chemical induction, show promise in converting glial cells into functional neurons. These approaches leverage the brain's intrinsic plasticity for neuronal replacement and circuit restoration. However, applying these genetic conversion therapies in the aged, post-stroke brain faces significant challenges, such as the hostile inflammatory environment and compromised regenerative capacity. There is a critical need for safe and efficient delivery methods, including viral and non-viral vectors, to ensure targeted and sustained expression of reprogramming factors. Moreover, addressing the translational gap between preclinical successes and clinical applications is essential, emphasizing the necessity for robust stroke models that replicate human pathophysiology. Ethical considerations and biosafety concerns are critically evaluated, particularly regarding the long-term effects and potential risks of genetic reprogramming. By integrating recent research findings, this comprehensive review provides an in-depth understanding of the current landscape and future prospects of genetic conversion therapy for ischemic stroke rehabilitation, highlighting the potential to enhance personalized stroke management and regenerative strategies through innovative approaches.

Targeting Drug Delivery System to Skeletal Muscles: A Comprehensive Review of Different Approaches

The skeletal muscle is one of the largest organs in the body and is responsible for the mechanical activity required for posture, movement and breathing. The effects of current pharmaceutical therapies for skeletal muscle diseases are far from satisfactory; approximately 24% of Duchenne muscular dystrophy (DMD) trials have been terminated because of unsatisfactory outcomes. The lack of a skeletal muscle-targeting strategy is a major reason for these unsuccessful trials, contributing to low efficiency and severe side effects. The development of targeting strategies for skeletal muscle-specific drug delivery has shown the potential for increasing drug concentrations in the skeletal muscle, minimising off-target effects, and thereby improving the therapeutic effects of drugs. Over the past few decades, novel methods for specifically delivering cargo to skeletal muscles have been developed. In this review, we categorise targeting methods into four types: peptides, antibodies, small molecules and aptamers. Most research has focused on peptide and antibody ligands, and there are several well-established drugs in this category; however, drawbacks such as protease degradation and immunogenicity limit their use. Aptamers and small molecules have low immunogenicity and are simple to chemically produce. However, small molecule ligands generally exhibit lower affinity because of their small size and high mobility. Aptamers are promising ligands for skeletal muscle-targeting delivery systems. Additionally, if the active site of the cargo is located inside the cell, an internalisation pathway becomes necessary. The order of internalisation ligands and targeting ligands in the complex is a crucial factor, because an inappropriate order could lead to much lower targeting and internalisation efficiencies. Moreover, ligand density also merits consideration, as increasing the density of the targeting ligands may result in steric hindrance, which could impact the accessibility of the receptor and cause enlargement of the targeted ligands. More efforts are required to optimise drug delivery systems that specifically recognise skeletal muscle, with the aim of enhancing quality of life and promoting patient well-being.

Model Organoids: Integrated Frameworks for the Next Frontier of Healthcare Advancements

The morphogenetic events leading to tissue formation can be recapitulated using organoids, which allows studying new diseases and modelling personalized medicines. In this review, culture systems comparable to human organs are presented, these organoids are created from pluripotent stem cells or adult stem cells. The efficient and reproducible models of human tissues are discussed for biobanking, precision medicine and basic research. Mechanisms used by these model systems with an overview of models from human cells are also covered. As human physiology is different from animals, culture conditions and tissue limits often become challenging. Organoids offer novel approaches for such cases with rapid screening, transplantation studies and in immunotherapy. Discrepancies with large datasets can be handled with an integrated framework of artificial intelligence or AI and machine learning. An attempt has been made to show the improved effectiveness, simplified iterations, along with image analysis that are possible from this synergy. AI-assisted organoids have the potential to transform healthcare by improving disease understanding and accelerating clinical decision-making through personalized and precision medicine.

Liver organoids: Current advances and future applications for hepatology

The creation of self-organizing liver organoids represents a significant, although modest, step toward addressing the ongoing organ shortage crisis in allogeneic liver transplantation. However, researchers have recognized that achieving a fully functional whole liver remains a distant goal, and the original ambition of organoid-based liver generation has been temporarily put on hold. Instead, liver organoids have revolutionized the field of hepatology, extending their influence into various domains of precision and molecular medicine. These 3D cultures, capable of replicating key features of human liver function and pathology, have opened new avenues for human-relevant disease modeling, CRISPR gene editing, and high-throughput drug screening that animal models cannot accomplish. Moreover, advancements in creating more complex systems have led to the development of multicellular assembloids, dynamic organoid-on-chip systems, and 3D bioprinting technologies. These innovations enable detailed modeling of liver microenvironments and complex tissue interactions. Progress in regenerative medicine and transplantation applications continues to evolve and strives to overcome the obstacles of biocompatibility and tumorigenecity. In this review, we examine the current state of liver organoid research by offering insights into where the field currently stands, and the pivotal developments that are shaping its future.

Two- and Three-Dimensional In Vitro Models of Parkinson's and Alzheimer's Diseases: State-of-the-Art and Applications

In vitro models play a pivotal role in advancing our understanding of neurodegenerative diseases (NDs) such as Parkinson's and Alzheimer's disease (PD and AD). Traditionally, 2D cell cultures have been instrumental in elucidating the cellular mechanisms underlying these diseases. Cultured cells derived from patients or animal models provide valuable insights into the pathological processes at the cellular level. However, they often lack the native tissue environment complexity, limiting their ability to fully recapitulate their features. In contrast, 3D models offer a more physiologically relevant platform by mimicking the 3D brain tissue architecture. These models can incorporate multiple cell types, including neurons, astrocytes, and microglia, creating a microenvironment that closely resembles the brain's complexity. Bioengineering approaches allow researchers to better replicate cell-cell interactions, neuronal connectivity, and disease-related phenotypes. Both 2D and 3D models have their advantages and limitations. While 2D cultures provide simplicity and scalability for high-throughput screening and basic processes, 3D models offer enhanced physiological relevance and better replicate disease phenotypes. Integrating findings from both model systems can provide a better understanding of NDs, ultimately aiding in the development of novel therapeutic strategies. Here, we review existing 2D and 3D in vitro models for the study of PD and AD.

Deciphering the physiopathology of neurodevelopmental disorders using brain organoids

Neurodevelopmental disorders (NDD) encompass a range of conditions marked by abnormal brain development in conjunction with impaired cognitive, emotional and behavioural functions. Transgenic animal models, mainly rodents, traditionally served as key tools for deciphering the molecular mechanisms driving NDD physiopathology and significantly contributed to the development of pharmacological interventions aimed at treating these disorders. However, the efficacy of these treatments in humans has proven to be limited, due in part to the intrinsic constraint of animal models to recapitulate the complex development and structure of the human brain but also to the phenotypic heterogeneity found between affected individuals. Significant advancements in the field of induced pluripotent stem cells (iPSCs) offer a promising avenue for overcoming these challenges. Indeed, the development of advanced differentiation protocols for generating iPSC-derived brain organoids gives an unprecedented opportunity to explore human neurodevelopment. This review provides an overview of how 3D brain organoids have been used to investigate various NDD (i.e. Fragile X syndrome, Rett syndrome, Angelman syndrome, microlissencephaly, Prader-Willi syndrome, Timothy syndrome, tuberous sclerosis syndrome) and elucidate their pathophysiology. We also discuss the benefits and limitations of employing such innovative 3D models compared to animal models and 2D cell culture systems in the realm of personalized medicine.

Global Knowledge Map and Emerging Research Trends in Induced Pluripotent Stem Cells and Hereditary Diseases: A CiteSpace-based Visualization and Analysis

The rise of induced pluripotent stem cells (iPSCs) technology has ushered in a landmark shift in the study of hereditary diseases. However, there is a scarcity of reports that offer a comprehensive and objective overview of the current state of research at the intersection of iPSCs and hereditary diseases. Therefore, this study endeavors to categorize and synthesize the publications in this field over the past decade through bibliometric methods and visual knowledge mapping, aiming to visually analyze their research focus and clinical trends. The English language literature on iPSCs and hereditary diseases, published from 2014 to 2023 in the Web of Science Core Collection (WoSCC), was examined. The CiteSpace (version 6.3.R1) software was utilized to visualize and analyze country/region, institution, scholar, co-cited authors, and co-cited journals. Additionally, the co-occurrence, clustering, and bursting of co-cited references were displayed. Analysis of 347 articles that met the inclusion criteria revealed a steady increase in the number of published articles and citation frequency in the field over the past decade. With regard to the countries/regions, institutions, scholars, and journals where the articles were published, the highest numbers were found in the USA, the University of California System, Suren M. Zakian, and Stem Cell Research, respectively. The current research is focused on the construction of disease models, both before and after correction, as well as drug target testing for single-gene hereditary diseases. Chromosome transplantation genomic therapy for hereditary diseases with abnormal chromosome structures may emerge as a future research hotspot in this field.

Forty Years of the Use of Cells for Cartilage Regeneration: The Research Side

Background: The treatment of articular cartilage damage has always represented a problem of considerable practical interest for orthopedics. Over the years, many surgical techniques have been proposed to induce the growth of repairing tissue and limit degeneration. In 1994, the turning point occurred: implanted autologous cells paved the way for a new treatment option based more on regeneration than repair. Objectives: This review aims to outline biological and clinical advances, from the use of mature adult chondrocytes to cell-derived products, going through progenitor cells derived from bone marrow or adipose tissue and their concentrates for articular cartilage repair. Moreover, it highlights the relevance of gene therapy as a valuable tool for successfully implementing current regenerative treatments, and overcoming the limitations of the local delivery of growth factors. Conclusions: Finally, this review concludes with an outlook on the importance of understanding the role and mechanisms of action of the different cell compounds with a view to implementing personalized treatments.

Bridging the Gap: Endothelial Dysfunction and the Role of iPSC-Derived Endothelial Cells in Disease Modeling

Endothelial cells (ECs) are crucial for vascular health, regulating blood flow, nutrient exchange, and modulating immune responses and inflammation. The impairment of these processes causes the endothelial dysfunction (ED) characterized by oxidative stress, inflammation, vascular permeability, and extracellular matrix remodeling. While primary ECs have been widely used to study ED in vitro, their limitations-such as short lifespan and donor variability-pose challenges. In this context, induced iECs derived from induced pluripotent stem cells offer an innovative solution, providing an unlimited source of ECs to explore disease-specific features of ED. Recent advancements in 3D models and microfluidic systems have enhanced the physiological relevance of iEC-based models by better mimicking the vascular microenvironment. These innovations bridge the gap between understanding ED mechanisms and drug developing and screening to prevent or treat ED. This review highlights the current state of iEC technology as a model to study ED in vascular and non-vascular disorders, including diabetes, cardiovascular, and neurodegenerative diseases.

Somatic piRNA and PIWI-mediated post-transcriptional gene regulation in stem cells and disease

PIWI-interacting RNAs (piRNAs) are small non-coding RNAs that bind to the PIWI subclass of the Argonaute protein family and are essential for maintaining germline integrity. Initially discovered in Drosophila, PIWI proteins safeguard piRNAs, forming ribonucleoprotein (RNP) complexes, crucial for regulating gene expression and genome stability, by suppressing transposable elements (TEs). Recent insights revealed that piRNAs and PIWI proteins, known for their roles in germline maintenance, significantly influence mRNA stability, translation and retrotransposon silencing in both stem cells and bodily tissues. In the current review, we explore the multifaceted roles of piRNAs and PIWI proteins in numerous biological contexts, emphasizing their involvement in stem cell maintenance, differentiation, and the development of human diseases. Additionally, we discussed the up-and-coming animal models, beyond the classical fruit fly and earthworm systems, for studying piRNA-PIWIs in self-renewal and cell differentiation. Further, our review offers new insights and discusses the emerging roles of piRNA-dependent and independent functions of PIWI proteins in the soma, especially the mRNA regulation at the post-transcriptional level, governing stem cell characteristics, tumor development, and cardiovascular and neurodegenerative diseases.

In Vitro Models of Cardiovascular Disease: Embryoid Bodies, Organoids and Everything in Between

Cardiovascular disease comprises a group of disorders affecting or originating within tissues and organs of the cardiovascular system; most, if not all, will eventually result in cardiomyocyte dysfunction or death, negatively impacting cardiac function. Effective models of cardiac disease are thus important for understanding crucial aspects of disease progression, while recent advancements in stem cell biology have allowed for the use of stem cell populations to derive such models. These include three-dimensional (3D) models such as stem cell-based models of embryos (SCME) as well as organoids, many of which are frequently derived from embryoid bodies (EB). Not only can they recapitulate 3D form and function, but the developmental programs governing the self-organization of cell populations into more complex tissues as well. Many different organoids and SCME constructs have been generated in recent years to recreate cardiac tissue and the complex developmental programs that give rise to its cellular composition and unique tissue morphology. It is thus the purpose of this narrative literature review to describe and summarize many of the recently derived cardiac organoid models as well as their use for the recapitulation of genetic and acquired disease. Owing to the cellular composition of the models examined, this review will focus on disease and tissue injury associated with embryonic/fetal tissues.