Induced pluripotent stem cells and their potential for basic and clinical sciences

Stem cell therapy for regenerating periodontal bony defects: A narrative review

Periodontal bony defects pose a significant challenge in periodontology, necessitating advanced regenerative approaches to restore the lost structures. Stem cell-based therapies have emerged as a promising solution due to their ability to differentiate into various cells, modulating the regenerative microenvironment. This narrative review explores the potential of stem cells derived from multiple sources in treating periodontal bony defects. Additionally, we examine evidence from both animal and human studies, highlighting advancements, clinical outcomes, and limitations. By investigating these findings, this article provides a comprehensive overview of the advantages of stem cell-based therapies compared to other regenerative techniques in addressing periodontal bony defects and discusses the limitations of their translation into routine clinical practice.

Stem Cells as a Novel Source for Regenerative Medicinal Applications in Alzheimer's Disease: An Update

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by loss of the neurons, excessive accumulation of misfolded Aβ and Tau proteins, and degeneration of neural synapses, primarily occurring in the neocortex and the hippocampus regions of the brain. AD Progression is marked by cognitive deterioration, memory decline, disorientation, and loss of problem-solving skills, as well as language. Due to limited comprehension of the factors contributing to AD and its severity due to neuronal loss, even today, the medications approved by the U.S. Food and Drug Administration (FDA) are not precisely efficient and curative. Stem cells possess great potential in aiding AD due to their self-renewal, proliferation, and differentiation properties. Stem cell therapy can aid by replacing the lost neurons, enhancing neurogenesis, and providing an enriched environment to the pre-existing neural cells. Stem cell therapy has provided us with promising results in regard to the animal AD models, and even pre-clinical studies have shown rather positive results. Cell replacement therapies are potential curative means to treat AD, and there are a number of undergoing human clinical trials to make Stem Cell therapy accessible for AD patients. In this review, we aim to discuss the AD pathophysiology and varied stem cell types and their application.

Dynamic three dimensional environment for efficient and large scale generation of smooth muscle cells from hiPSCs

BACKGROUND

Chronic ischemic limb disease often leads to amputation, which remains a significant clinical problem. Smooth-muscle cells (SMCs) are crucially involved in the development and progression of many cardiovascular diseases, but studies with primary human SMCs have been limited by a lack of availability. Here, we evaluated the efficiency of two novel protocols for differentiating human induced-pluripotent stem cells (hiPSCs) into SMCs and assessed their potency for the treatment of ischemic limb disease.

METHODS

hiPSCs were differentiated into SMCs via a conventional two-dimensional (2D) protocol that was conducted entirely with cell monolayers, or via two protocols that consisted of an initial five-day three-dimensional (3D) spheroid phase followed by a six-day 2D monolayer phase (3D + 2D differentiation). The 3D phases were conducted in shaker flasks on an orbital shaker (the 3D + 2D shaker protocol) or in a PBS bioreactor (the 3D + 2D bioreactor protocol). Differentiation efficiency was evaluated via the expression of SMC markers (smooth-muscle actin [SMA], smooth muscle protein 22 [SM22], and Calponin-1), and the biological activity of the differentiated hiPSC-SMCs was evaluated via in-vitro assessments of migration (scratch assay), contraction in response to the treatment with a prostaglandin H2 analog (U46619), and tube formation on Geltrex, as well as in-vivo measurements of perfusion (fluorescence angiography) and vessel density in the limbs of mice that were treated with hiPSC-SMCs after experimentally induced hind-limb ischemia (HLI).

RESULTS

Both 3D + 2D protocols yielded > 5.6 × 107 hiPSC-SMCs/differentiation, which was ~ nine-fold more than that produced via 2D differentiation, and flow cytometry analyses confirmed that > 98% of the 3D + 2D-differentiated hiPSC-SMCs expressed SMA, > 81% expressed SM22, and > 89% expressed Calponin-1. hiPSC-SMCs obtained via the 3D + 2D shaker protocol also displayed typical SMC-like migratory, contraction, and tube-formation activity in-vitro and significantly improved measurements of perfusion, vessel density, and SMA-positive arterial density in the ischemic limb of mouse HLI model.

CONCLUSIONS

Our dynamic 3D + 2D protocols produced an exceptionally high yield of hiPSC-SMCs. Transplantation of these hiPSC-SMCs results in significantly improved recovery of ischemic limb after ischemic injury in mice.

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

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

Osteosarcoma: A comprehensive review of model systems and experimental therapies

Osteosarcoma (OSA) is a highly malignant bone tumor for which more than 50% of patients have or will develop metastatic disease, resulting in an abysmal 5-year survival rate of <29%. Despite the advances in science and medicine, the etiology of OSA remains unclear. Similarly, the standard of care (surgery and chemotherapy) has changed little in the past 5 decades. This stagnation in treatment options is in part due to inadequate preclinical models for OSA; many of these models are oversimplified and do not account for the complexities of patient disease. Further, current treatments are harsh and invasive (e.g. high dose chemotherapy and potential limb removal) leading to a reduction in a patient's quality of life (e.g. hearing loss, infertility, neuropathy), highlighting a need for developing more effective treatment strategies. Many experimental therapies have been tested in the preclinical and preclinical setting, with varying degrees of success. In this review, we will focus on pediatric and adolescent OSA, highlighting current animal models and experimental therapies.

Cardiac Tissue Engineering: A Journey from Scaffold Fabrication to In Vitro Characterization

Cardiac tissue engineering has been rapidly evolving with diverse applications, ranging from the repair of fibrotic tissue caused by "adverse remodeling," to the replacement of specific segments of heart tissue, and ultimately to the creation of a whole heart. The repair or replacement of cardiac tissue often involves the development of tissue scaffolds or constructs and the subsequent assessment of their performance and functionality. For this, the design and/or selection of biomaterials, and cell types, scaffold fabrication, and in vitro characterizations are the first starting points, yet critical, to ensure success in subsequent implantation in vivo. This highlights the importance of scaffold fabrication and in vitro experiments/characterization with protocols for cardiac tissue engineering. Yet, a comprehensive and critical review of these has not been established and documented. As inspired, herein, the latest development and advances in scaffold fabrication and in vitro characterization for cardiac tissue engineering are critically reviewed, with focus on biomaterials, cell types, additive manufacturing techniques for scaffold fabrication, and common in vitro characterization techniques or methods. This article would be of benefit to the ones who are working on cardiac tissue engineering by providing insights into the scaffold fabrication and in vitro investigations.

Generation of induced pluripotent stem cells from the Asian bats

Preservation of native Korean bats is crucial for maintaining ecological balance, as they play a vital role in insect control, pollination, and seed dispersal within their ecosystems. The present study details the establishment of bat induced pluripotent stem cells (BatiPSCs) from two Asian and Korean bats (Hypsugo alaschanicus and Pipistrellus abramus) using the Sendai Reprogramming Kit. Colonies of BatiPSCs, exhibiting distinctive features, were manually selected and expanded following successful transfection. Characterization of BatiPSCs revealed the expression of pluripotency markers, such as Octamer-binding transcription factor 4 (Oct4), SRY (sex-determining region Y)-box 2 and Nanog, with notably increased Oct4 levels and reduced Myc proto-oncogene expression compared with those noted in other induced pluripotent stem cell sources. BatiPSCs displayed positive staining for alkaline phosphatase and demonstrated the ability to form embryoid bodies, while also inducing teratomas in non-immune nude mice. Additionally, green fluorescent protein (GFP)-expressing BatiPSCs were generated and used for chimeric mouse production, with slight GFP signals detected in the neck region of the resulting mouse foetuses. These findings demonstrate the successful generation and characterization of BatiPSCs, emphasizing their potential applications in chimeric animal models, and the protection of endangered bat species.

An induced pluripotent stem cell-based approach for hair follicle development and regeneration

Because hair loss is a common concern for many individuals, potential regenerative therapies of hair follicles have been extensively researched. Induced pluripotent stem cells (iPSCs) are a promising avenue for hair follicle regeneration. This review explores current iPSC-based approaches and highlights their potential applications and challenges in hair restoration. The principles of iPSC technology, iPSC differentiation into hair follicle precursor cells, and potential clinical implications for hair follicle regeneration are also discussed. This overview of iPSCs and their applications aims to contribute to our understanding of their role in hair restoration and potential future therapeutic applications.

Advancements in tissue engineering for articular cartilage regeneration

Articular cartilage injury is a prevalent clinical condition resulting from trauma, tumors, infection, osteoarthritis, and other factors. The intrinsic lack of blood vessels, nerves, and lymphatic vessels within cartilage tissue severely limits its self-regenerative capacity after injury. Current treatment options, such as conservative drug therapy and joint replacement, have inherent limitations. Achieving perfect regeneration and repair of articular cartilage remains an ongoing challenge in the field of regenerative medicine. Tissue engineering has emerged as a key focus in articular cartilage injury research, aiming to utilize cultured and expanded tissue cells combined with suitable scaffold materials to create viable, functional tissues. This review article encompasses the latest advancements in seed cells, scaffolds, and cytokines. Additionally, the role of stimulatory factors including cytokines and growth factors, genetic engineering techniques, biophysical stimulation, and bioreactor systems, as well as the role of scaffolding materials including natural scaffolds, synthetic scaffolds, and nanostructured scaffolds in the regeneration of cartilage tissues are discussed. Finally, we also outline the signaling pathways involved in cartilage regeneration. Our review provides valuable insights for scholars to address the complex problem of cartilage regeneration and repair.

Pulmonary fibrosis: Is stem cell therapy the way forward?

Pulmonary fibrosis, a chronic and fatal lung disease affecting millions of people worldwide, is characterized by the scarring of lung tissue, thereby impairing oxygen exchange between the lungs and blood. The etiology of pulmonary fibrosis is multifactorial, involving environmental exposures, comorbidities, and genetic mutations. Current pharmacological treatments can only slow the disease progression, and lung transplantation is limited by donor availability and complications. Stem cell therapy has emerged as a potential alternative treatment for pulmonary fibrosis, in which stem cells modulate the inflammatory response, differentiate into lung epithelial cells, secrete growth factors and extracellular matrix components, and enhance vascularization and tissue regeneration. Various sources of stem cells, such as endogenous lung stem cells, embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells, have been investigated in animal models and human trials. Various delivery routes, such as intravenous injection, intratracheal instillation, and inhalation, have been tested for safety and efficacy. However, several challenges and limitations remain to be overcome, such as high costs, ethical issues, immunological compatibility, cell survival and homing, and long-term outcomes. Further research is needed to optimize the protocols and parameters in stem cell therapy for pulmonary fibrosis, and to evaluate the clinical benefits and risks for patients.

Advancements in Periodontal Regeneration: A Comprehensive Review of Stem Cell Therapy

Periodontal disease, characterized by inflammation and infection of the supporting structures of teeth, presents a significant challenge in dentistry and public health. Current treatment modalities, while effective to some extent, have limitations in achieving comprehensive periodontal tissue regeneration. This comprehensive review explores the potential of stem cell therapy in advancing the field of periodontal regeneration. Stem cells, including mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs), hold promise due to their immunomodulatory effects, differentiation potential into periodontal tissues, and paracrine actions. Preclinical studies using various animal models have revealed encouraging outcomes, though standardization and long-term assessment remain challenges. Clinical trials and case studies demonstrate the safety and efficacy of stem cell therapy in real-world applications, especially in personalized regenerative medicine. Patient selection criteria, ethical considerations, and standardized treatment protocols are vital for successful clinical implementation. Stem cell therapy is poised to revolutionize periodontal regeneration, offering more effective, patient-tailored treatments while addressing the systemic health implications of periodontal disease. This transformative approach holds the potential to significantly impact clinical practice and improve the overall well-being of individuals affected by this prevalent oral health concern. Responsible regulatory compliance and a focus on ethical considerations will be essential as stem cell therapy evolves in periodontal regeneration.

Regeneration of the Retina Using Pluripotent Stem Cells: A Comprehensive Review

Retinitis pigmentosa and age-related macular degeneration are the most frequent causes of irreversible visual impairment in the world. Existing therapeutic methods could be more effective, underscoring the necessity of new treatments. Reconstructing the retinal photoreceptors through the transplantation of human pluripotent stem cells, representing an attractive approach for restoring vision, has gained momentum. This paper gives an exhaustive account of what has been known in this field, the discoveries made, and the recent progress. This review paper outlines the retina's organisation, cell types, the pathophysiology of retinal injury/degeneration, and the reasoning behind using pluripotent stem cells in retinal regeneration. This article investigates differentiation strategies, molecular components that dictate cell type specification, and the recreation of retinal development in vitro, genetically engineering and manipulating epigenetic marks using various techniques for driving specific cell fates and improving therapy efficacy. Subretinal injection methods, cell encapsulation techniques, scaffold-based approaches, cell sheet transplantation, and their impact on integrating implanted cells into a functional retina are thoroughly reviewed. Using bioengineering approaches, biomaterials and growth factors form a favourable micro-ambience for grafted cells. Issues around safety and efficacy (tumorigenicity, immunological rejection, and long-term integration/functionality) are explored. Moreover, the paper emphasises the significance of rigorous characterisation, immunomodulatory strategies, and clinical and pre-clinical studies to ensure the safety and effectiveness of retinal regeneration therapy. Future perspectives and challenges are presented, looking at fine-tuning differentiation strategies, improving functional integration and regulatory aspects, and using co-therapy and supportive treatments.

Understanding the genetic mechanisms and cognitive impairments in Down syndrome: towards a holistic approach

The most common genetic cause of intellectual disability is Down syndrome (DS), trisomy 21. It commonly results from three copies of human chromosome 21 (HC21). There are no mutations or deletions involved in DS. Instead, the phenotype is caused by altered transcription of the genes on HC21. These transcriptional variations are responsible for a myriad of symptoms affecting every organ system. A very debilitating aspect of DS is intellectual disability (ID). Although tremendous advances have been made to try and understand the underlying mechanisms of ID, there is a lack of a unified, holistic view to defining the cause and managing the cognitive impairments. In this literature review, we discuss the mechanisms of neuronal over-inhibition, abnormal morphology, and other genetic factors in contributing to the development of ID in DS patients and to gain a holistic understanding of ID in DS patients. We also highlight potential therapeutic approaches to improve the quality of life of DS patients.

Stem Cell-Based Modeling Protocol for Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative disorder, which is mainly characterized by unintended or uncontrollable body movements. Pathophysiologically, disturbances in the neurotransmission system of the brain like dopaminergic system and synaptic dysfunction are classified as top-rated causes of the onset of Parkinson's disease, which symptoms can be different according to the involvement of neurotransmission system type and the effect of the disease on the motor and non-motor systems. Although some pharmacological and non-pharmacological approaches have been applied to control and slow down the progression of the disease, a definitive cure has not yet been discovered. One of the factors involved in this issue is the lack of appropriate laboratory models to investigate the pathological mechanisms involved in the disease as well as various aspects of candidate drugs, which ultimately leads to the failure of drug discovery and development pipelines. To deal with these challenges, the application of stem cells, especially cellular reprogramming of somatic cells to human pluripotent stem cells, also known as induced pluripotent stem cells, has been able to promise a new chapter in the modeling of Parkinson's disease. Induced pluripotent stem cells have the stemness capability; therefore, they can differentiate into any type of cell such as nerve cells. Also, since these cells are obtained from the reprogramming of somatic cells in the patient's body, they maintain the patient's genetic content, which can play an important role in increasing the quality of disease modeling and the validity of the results of laboratory studies. Therefore, the procedure for modeling induced pluripotent stem cells for Parkinson's disease is explained in this chapter.

Immunomodulatory effects of the induced pluripotent stem cells through expressing IGF-related factors and IL-10 in vitro

BACKGROUND

Induced Pluripotent Stem Cells (IPSCs) represent an innovative strategy for addressing challenging diseases, including various rheumatologic conditions. Aside from their regenerative capacities, some studies have shown the potential of these cells in the modulation of inflammatory responses. The underlying mechanisms by which they exert their effects have yet to be fully comprehended. Therefore, we aimed to explore the gene expression linked to the IGF pathway as well as IL-10 and TGF-β, which are known to exert immunomodulatory effects.

METHODS

A C57/Bl6 pregnant mouse was used for obtaining mouse embryonic fibroblasts (MEFs), then the IPSCs were induced using lentiviral vectors expressing the pluripotency genes (OCT4, SOX2, KLF1, and c-MYC). Cells were cultured for 72 h in DMEM high glucose plus leukemia inhibitory factor; Evaluating the gene expression was conducted using specific primers for Igf1, Igf2, Igfbp3, Igfbp4, Irs1, Il-10, and Tgf-β genes, as well as SYBR green qPCR master mix. The data were analyzed using the 2-ΔΔCT method and were compared by employing the t test; the results were plotted using GraphPad PRISM software. MEFs were utilized as controls.

RESULTS

Gene expression analyses revealed that Igf-1, Igf-bp3, Igf-bp4, and Il-10 were significantly overexpressed (p ≤ .01), while Igf-2 and Tgf-b genes were significantly downregulated in the lysates from IPSCs in comparison with the control MEFs. The Irs1 gene expression was not altered significantly.

CONCLUSION

IPSCs are potentially capable of modulating inflammatory responses through the expression of various anti-inflammatory mediators from the IGF signaling, as well as IL-10. This discovery uncovers a previously unknown dimension of IPSCs' therapeutic effects, potentially leading to more advanced in vivo research and subsequent clinical trials.

Potential of Nano-Engineered Stem Cells in the Treatment of Multiple Sclerosis: A Comprehensive Review

Multiple sclerosis (MS) is a chronic and degrading autoimmune disorder mainly targeting the central nervous system, leading to progressive neurodegeneration, demyelination, and axonal damage. Current treatment options for MS are limited in efficacy, generally linked to adverse side effects, and do not offer a cure. Stem cell therapies have emerged as a promising therapeutic strategy for MS, potentially promoting remyelination, exerting immunomodulatory effects and protecting against neurodegeneration. Therefore, this review article focussed on the potential of nano-engineering in stem cells as a therapeutic approach for MS, focusing on the synergistic effects of combining stem cell biology with nanotechnology to stimulate the proliferation of oligodendrocytes (OLs) from neural stem cells and OL precursor cells, by manipulating neural signalling pathways-PDGF, BMP, Wnt, Notch and their essential genes such as Sox, bHLH, Nkx. Here we discuss the pathophysiology of MS, the use of various types of stem cells in MS treatment and their mechanisms of action. In the context of nanotechnology, we present an overview of its applications in the medical and research field and discuss different methods and materials used to nano-engineer stem cells, including surface modification, biomaterials and scaffolds, and nanoparticle-based delivery systems. We further elaborate on nano-engineered stem cell techniques, such as nano script, nano-exosome hybrid, nano-topography and their potentials in MS. The article also highlights enhanced homing, engraftment, and survival of nano-engineered stem cells, targeted and controlled release of therapeutic agents, and immunomodulatory and tissue repair effects with their challenges and limitations. This visual illustration depicts the process of utilizing nano-engineering in stem cells and exosomes for the purpose of delivering more accurate and improved treatments for Multiple Sclerosis (MS). This approach targets specifically the creation of oligodendrocytes, the breakdown of which is the primary pathological factor in MS.

Cell-based Therapies for Corneal and Retinal Disorders

Maintenance of the visual function is the desired outcome of ophthalmologic therapies. The shortcomings of the current treatment options, like partial recovery, post-operation failure, rigorous post-operative care, complications, etc., which are usually encountered with the conventional treatment options has warranted newer treatment options that may eliminate the root cause of diseases and minimize the side effects. Cell therapies, a class of regenerative medicines, have emerged as cutting-edge treatment option. The corneal and retinal dystrophies during the ocular disorders are the major cause of blindness, worldwide. Corneal disorders are mainly categorized mainly into corneal epithelial, stromal, and endothelial disorders. On the other hand, glaucoma, retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy, Stargardt Disease, choroideremia, Leber congenital amaurosis are then major retinal degenerative disorders. In this manuscript, we have presented a detailed overview of the development of cell-based therapies, using embryonic stem cells, bone marrow stem cells, mesenchymal stem cells, dental pulp stem cells, induced pluripotent stem cells, limbal stem cells, corneal epithelial, stromal and endothelial, embryonic stem cell-derived differentiated cells (like retinal pigment epithelium or RPE), neural progenitor cells, photoreceptor precursors, and bone marrow-derived hematopoietic stem/progenitor cells etc. The manuscript highlights their efficiency, drawbacks and the strategies that have been explored to regain visual function in the preclinical and clinical state associated with them which can be considered for their potential application in the development of treatment.

Harnessing the Therapeutic Potential of Stem Cells in the Management of Chronic Obstructive Pulmonary Disease: A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is a prevalent and debilitating respiratory condition with limited treatment options. Stem cell therapy has emerged as a promising approach for COPD management due to its regenerative and immunomodulatory properties. This review article aims to comprehensively explore the therapeutic potential of stem cells in COPD management. The introduction provides background on COPD, highlighting its impact on health and the need for novel therapies. The different types of stem cells relevant to COPD, including embryonic stem cells, adult stem cells, and induced pluripotent stem cells, are described along with their properties and characteristics. The pathogenesis of COPD is discussed, emphasizing the key mechanisms involved in disease development and progression. Subsequently, the role of stem cells in tissue repair, regeneration, and immunomodulation is examined, highlighting their ability to address specific pathological processes in COPD. Mechanisms of action, such as paracrine signaling, immunomodulation, anti-inflammatory effects, and tissue regeneration, are explored. The interaction between stem cells and the host environment, which promotes lung repair, is also discussed. Challenges in stem cell therapy for COPD, including optimal cell sources, delivery methods, safety, and efficacy, are identified. Regulatory considerations and the importance of standardization are emphasized. Potential strategies for optimizing the therapeutic potential of stem cells in COPD management, such as combination therapies and preconditioning techniques, are outlined. Emerging trends and future directions are highlighted, including advanced cell engineering and patient-specific induced pluripotent stem cells. In conclusion, stem cell therapy holds significant promise for COPD management, addressing the limitations of current treatments. Continued research and development are necessary to overcome challenges, optimize therapies, and realize stem cells' full potential in improving the lives of patients with COPD.

An update on stem cell and stem cell-derived extracellular vesicle-based therapy in the management of Alzheimer's disease

Globally, neurological diseases pose a major burden to healthcare professionals in terms of the management and prevention of the disorder. Among neurological diseases, Alzheimer's disease (AD) accounts for 50%-70% of dementia and is the fifth leading cause of mortality worldwide. AD is a progressive, degenerative neurological disease, with the loss of neurons and synapses in the cerebral cortex and subcortical regions. The management of AD remains a debate among physicians as no standard and specific "disease-modifying" modality is available. The concept of 'Regenerative Medicine' is aimed at regenerating the degenerated neural tissues to reverse the pathology in AD. Genetically modified engineered stem cells modify the course of AD after transplantation into the brain. Extracellular vesicles (EVs) are an emerging new approach in cell communication that involves the transfer of cellular materials from parental cells to recipient cells, resulting in changes at the molecular and signaling levels in the recipient cells. EVs are a type of vesicle that can be transported between cells. Many have proposed that EVs produced from mesenchymal stem cells (MSCs) may have therapeutic promise in the treatment of AD. The biology of AD, as well as the potential applications of stem cells and their derived EVs-based therapy, were explored in this paper.

Biomimetic Strategies for Peripheral Nerve Injury Repair: An Exploration of Microarchitecture and Cellularization

Injuries to the nervous system present formidable challenges to scientists, clinicians, and patients. While regeneration within the central nervous system is minimal, peripheral nerves can regenerate, albeit with limitations. The regenerative mechanisms of the peripheral nervous system thus provide fertile ground for clinical and scientific advancement, and opportunities to learn fundamental lessons regarding nerve behavior in the context of regeneration, particularly the relationship of axons to their support cells and the extracellular matrix environment. However, few current interventions adequately address peripheral nerve injuries. This article aims to elucidate areas in which progress might be made toward developing better interventions, particularly using synthetic nerve grafts. The article first provides a thorough review of peripheral nerve anatomy, physiology, and the regenerative mechanisms that occur in response to injury. This is followed by a discussion of currently available interventions for peripheral nerve injuries. Promising biomaterial fabrication techniques which aim to recapitulate nerve architecture, along with approaches to enhancing these biomaterial scaffolds with growth factors and cellular components, are then described. The final section elucidates specific considerations when developing nerve grafts, including utilizing induced pluripotent stem cells, Schwann cells, nerve growth factors, and multilayered structures that mimic the architectures of the natural nerve.

Conditioned Medium - Is it an Undervalued Lab Waste with the Potential for Osteoarthritis Management?

BACKGROUND

The approaches currently used in osteoarthritis (OA) are mainly short-term solutions with unsatisfactory outcomes. Cell-based therapies are still controversial (in terms of the sources of cells and the results) and require strict culture protocol, quality control, and may have side-effects. A distinct population of stromal cells has an interesting secretome composition that is underrated and commonly ends up as biological waste. Their unique properties could be used to improve the existing techniques due to protective and anti-ageing properties.

SCOPE OF REVIEW

In this review, we seek to outline the advantages of the use of conditioned media (CM) and exosomes, which render them superior to other cell-based methods, and to summarise current information on the composition of CM and their effect on chondrocytes.

MAJOR CONCLUSIONS

CM are obtainable from a variety of mesenchymal stromal cell (MSC) sources, such as adipose tissue, bone marrow and umbilical cord, which is significant to their composition. The components present in CMs include proteins, cytokines, growth factors, chemokines, lipids and ncRNA with a variety of functions. In most in vitro and in vivo studies CM from MSCs had a beneficial effect in enhance processes associated with chondrocyte OA pathomechanism.

GENERAL SIGNIFICANCE

This review summarises the information available in the literature on the function of components most commonly detected in MSC-conditioned media, as well as the effect of CM on OA chondrocytes in in vitro culture. It also highlights the need to standardise protocols for obtaining CM, and to conduct clinical trials to transfer the effects obtained in vitro to human subjects.

Induced pluripotent stem cells: Generation methods and a new perspective in COVID-19 research

Induced pluripotent stem cells (iPSCs) exhibit an unlimited ability to self-renew and produce various differentiated cell types, thereby creating high hopes for both scientists and patients as a great tool for basic research as well as for regenerative medicine purposes. The availability and safety of iPSCs for therapeutic purposes require safe and highly efficient methods for production of these cells. Different methods have been used to produce iPSCs, each of which has advantages and disadvantages. Studying these methods would be very helpful in developing an easy, safe, and efficient method for the generation of iPSCs. Since iPSCs can be generated from somatic cells, they can be considered as valuable cellular resources available for important research needs and various therapeutic purposes. Coronavirus disease 2019 (COVID-19) is a disease that has endangered numerous human lives worldwide and currently has no definitive cure. Therefore, researchers have been rigorously studying and examining all aspects of COVID-19 and potential treatment modalities and various drugs in order to enable the treatment, control, and prevention of COVID-19. iPSCs have become one of the most attractive and promising tools in this field by providing the ability to study COVID-19 and the effectiveness of drugs on this disease outside the human body. In this study, we discuss the different methods of generation of iPSCs as well as their respective advantages and disadvantages. We also present recent applications of iPSCs in the study and treatment of COVID-19.

Forthcoming complications in recovered COVID-19 patients with COPD and asthma; possible therapeutic opportunities

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been growing swiftly worldwide. Patients with background chronic pulmonary inflammations such as asthma or chronic obstructive pulmonary diseases (COPD) are likely to be infected with this virus. Of note, there is an argument that COVID-19 can remain with serious complications like fibrosis or other pathological changes in the pulmonary tissue of patients with chronic diseases. Along with conventional medications, regenerative medicine, and cell-based therapy could be alternative approaches to compensate for organ loss or restore injured sites using different stem cell types. Owing to unique differentiation capacity and paracrine activity, these cells can accelerate the healing procedure. In this review article, we have tried to scrutinize different reports related to the harmful effects of SARS-CoV-2 on patients with asthma and COPD, as well as the possible therapeutic effects of stem cells in the alleviation of post-COVID-19 complications. Video abstract.

The Role of Amino Acids in Endothelial Biology and Function

The vascular endothelium acts as an important component of the vascular system. It is a barrier between the blood and vessel wall. It plays an important role in regulating blood vessel tone, permeability, angiogenesis, and platelet functions. Several studies have shown that amino acids (AA) are key regulators in maintaining vascular homeostasis by modulating endothelial cell (EC) proliferation, migration, survival, and function. This review summarizes the metabolic and signaling pathways of AAs in ECs and discusses the importance of AA homeostasis in the functioning of ECs and vascular homeostasis. It also discusses the challenges in understanding the role of AA in the development of cardiovascular pathophysiology and possible directions for future research.

The epigenetic-metabolic interplay in gliomagenesis

Although tumourigenesis occurs due to genetic mutations, the role of epigenetic dysregulations in cancer is also well established. Epigenetic dysregulations in cancer may occur as a result of mutations in genes encoding histone/DNA-modifying enzymes and chromatin remodellers or mutations in histone protein itself. It is also true that misregulated gene expression without genetic mutations in these factors could also support tumour initiation and progression. Interestingly, metabolic rewiring has emerged as a hallmark of cancer due to gene mutations in specific metabolic enzymes or dietary/environmental factors. Recent studies report an intricate cross-talk between epigenetic and metabolic reprogramming in cancer. This review discusses the role of epigenetic and metabolic dysregulations and their cross-talk in tumourigenesis with a special focus on gliomagenesis. We also discuss the role of recently developed human embryonic stem cells/induced pluripotent stem cells-derived organoid models of gliomas and how these models are proving instrumental in uncovering human-specific cellular and molecular complexities of gliomagenesis.

Hierarchically Structured Polystyrene-Based Surfaces Amplifying Fluorescence Signals: Cytocompatibility with Human Induced Pluripotent Stem Cell

An innovative multi-step phase separation process was used to prepare tissue culture for the polystyrene-based, hierarchically structured substrates, which mimicked in vivo microenvironment and architecture. Macro- (pore area from 3000 to 18,000 µm²; roughness (Ra) 7.2 ± 0.1 µm) and meso- (pore area from 50 to 300 µm²; Ra 1.1 ± 0.1 µm) structured substrates covered with micro-pores (area around 3 µm²) were prepared and characterised. Both types of substrate were suitable for human-induced pluripotent stem cell (hiPSC) cultivation and were found to be beneficial for the induction of cardiomyogenesis in hiPSC. This was confirmed both by the number of promoted proliferated cells and the expressions of specific markers (Nkx2.5, MYH6, MYL2, and MYL7). Moreover, the substrates amplified the fluorescence signal when Ca²⁺ flow was monitored. This property, together with cytocompatibility, make this material especially suitable for in vitro studies of cell/material interactions within tissue-mimicking environments.

Stem Cells as a Model of Study of SARS-CoV-2 and COVID-19: A Systematic Review of the Literature

BACKGROUND

The SARS-CoV-2 virus is the cause of the latest pandemic of the 21st century; it is responsible for the development of COVID-19. Within the multiple study models for both the biology and the treatment of SARS-CoV-2, the use of stem cells has been proposed because of their ability to increase the immune response and to repair tissue. Therefore, the objective of this review is to evaluate the role of stem cells against SARS-CoV-2 and COVID-19 in order to identify their potential as a study model and as a possible therapeutic source against tissue damage caused by this virus. Therefore, the following research question was established: What is the role of stem cells in the study of SARS-CoV-2 and the treatment of COVID-19?

MATERIALS AND METHODS

A search was carried out in the electronic databases of PUBMED, Scopus, and ScienceDirect. The following keywords were used: "SARS-CoV-2," "COVID-19," and "STEM CELL," plus independent search strategies with the Boolean operators "OR" and "AND." The identified reports were those whose main objective was the study of stem cells in relation to SARS-CoV-2 or COVID-19. For the development of this study, the following inclusion criteria were taken into account: studies whose main objective was the study of stem cells in relation to SARS-CoV-2 or COVID-19 and clinical case studies, case reports, clinical trials, pilot studies, in vitro, or in vivo studies. For assessment of the risk of bias for in vitro studies, the SciRAP tool was used. The data collected for each type of study, clinical or in vitro, were analyzed with descriptive statistics using the SPSS V.22 program.

RESULTS

Of the total of studies included (n = 39), 22 corresponded to in vitro investigations and 17 to human studies (clinical cases (n = 9), case series (n = 2), pilot clinical trials (n = 5), clinical trials (n = 1)). In vitro studies that induced pluripotent stem cells were the most used (n = 12), and in clinical studies, the umbilical stem cells derived were the most reported (n = 11). The mean age of the study subjects was 58.3 years. After the application of stem cell therapy, the follow-up period was 8 days minimum and 90 days maximum. Discussion. The mechanism by which the virus enters the cell is through protein "S," located on the surface of the membrane, by recognizing the ACE2 receptor located on the target cell. The evidence that the expression of ACE2 and TMPRSS2 in stem cells indicates that stem cells from bone marrow and amniotic fluid have very little expression. This shows that stem cell has a low risk of infection with SARS-CoV-2.

CONCLUSION

The use of stem cells is a highly relevant therapeutic option. It has been shown in both in vitro studies and clinical trials that it counteracts the excessive secretion of cytokines. There are even more studies that focus on long-term follow-up; thus, the potential for major side effects can be analyzed more clearly. Finally, the ethical use of stem cells from fetal or infant origin needs to be regulated. The study was registered in PROSPERO (no. CRD42021229038). The limitations of the study were because of the methodology employed, the sample was not very large, and the follow-up period of the clinical studies was relatively short.

Pluripotent and Multipotent Stem Cells and Current Therapeutic Applications: Review

There is numerous evidence for the presence of stem cells, which is important for the treatment of a wide variety of disease conditions. Stem cells have a great therapeutic effect on different degenerative diseases through the development of specialized cells. Embryonic stem (ES) cells are derived from preimplantation embryos, which have a natural karyotype. This cell has the capacity of proliferation indefinitely and undifferentiated. Stem cells are very crucial for the treatment of different chronic and degenerative diseases. For instance, stem cell clinical trials have been done for ischemic heart disease. Also, the olfactory cells for spinal cord lesions and human fetal pancreatic cells for diabetes mellitus are the other clinical importance of stem cell therapy. Extracellular matrix (ECM) and other environmental factors influence the fate and activity of stem cells.

Ion channels and pain in Fabry disease

Fabry disease (FD) is a progressive, X-linked inherited disorder of glycosphingolipid metabolism due to deficient or absent lysosomal α-galactosidase A (α-Gal A) activity which results in progressive accumulation of globotriaosylceramide (Gb3) and related metabolites. One prominent feature of Fabry disease is neuropathic pain. Accumulation of Gb3 has been documented in dorsal root ganglia (DRG) as well as other neurons, and has lately been associated with the mechanism of pain though the pathophysiology is still unclear. Small fiber (SF) neuropathy in FD differs from other entities in several aspects related to the perception of pain, alteration of fibers as well as drug therapies used in the practice with patients, with therapies far from satisfying. In order to develop better treatments, more information on the underlying mechanisms of pain is needed. Research in neuropathy has gained momentum from the development of preclinical models where different aspects of pain can be modelled and further analyzed. This review aims at describing the different in vitro and FD animal models that have been used so far, as well as some of the insights gained from their use. We focus especially in recent findings associated with ion channel alterations -that apart from the vascular alterations-, could provide targets for improved therapies in pain.

A2E-associated cell death and inflammation in retinal pigmented epithelial cells from human induced pluripotent stem cells

Accumulation of lipofuscin in the retinal pigmented epithelium (RPE) is observed in retinal degenerative diseases including Stargardt disease and age-related macular degeneration. Bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E) is a major component of lipofuscin. A2E has been implicated in RPE atrophy and retinal inflammation; however, mice with A2E accumulation display only a mild retinal phenotype. In the current study, human iPSC-RPE (hiPSC-RPE) cells were generated from healthy individuals to examine effects of A2E in human RPE cells. hiPSC-RPE cells displayed RPE-specific features, which include expression of RPE-specific genes, tight junction formation and ability to carry out phagocytosis. hiPSC-RPE cells demonstrated cell death and increased VEGF-A production in a time-dependent manner when they were cocultured with 10 μM of A2E. PCR array analyses revealed upregulation of 26 and 12 pro-inflammatory cytokines upon A2E and H₂O₂ exposure respectively, indicating that A2E and H₂O₂ can cause inflammation in human retinas. Notably, identified gene profiles were different between A2E- and H₂O₂-treated hiPSC-RPE cells. A2E caused inflammatory changes observed in retinal degenerative diseases more closely as compared to H₂O₂. Collectively, these data obtained with hiPSC-RPE cells provide evidence that A2E plays an important role in pathogenesis of retinal degenerative diseases in humans.

Advances in the Use of Stem Cells in Veterinary Medicine: From Basic Research to Clinical Practice

Today, several veterinary diseases may be treated with the administration of stem cells. This is possible because these cells present a high therapeutic potential and may be injected as autologous or allogenic, freshly isolated, or previously cultured. The literature supports that the process is safe and brings considerable benefits to animal health. Knowledge about how adult stem cells modulate the molecular signals to activate cell homing has also been increasingly determined, evidencing the mechanisms which enable cells to repair and regenerate injured tissues. Preclinical studies were designed for many animal models and they have contributed to the translation to the human clinic. This review shows the most commonly used stem cell types, with emphasis on mesenchymal stem cells and their mechanistic potential to repair, as well as the experimental protocols, studied diseases, and species with the highest amount of studies and applications. The relationship between stem cell protocols utilized on clinics, molecular mechanisms, and the physiological responses may offer subsidies to new studies and therefore improve the therapeutic outcome for both humans and animals.

Generation of functional podocytes from human induced pluripotent stem cells

Generating human podocytes in vitro could offer a unique opportunity to study human diseases. Here, we describe a simple and efficient protocol for obtaining functional podocytes in vitro from human induced pluripotent stem cells. Cells were exposed to a three-step protocol, which induced their differentiation into intermediate mesoderm, then into nephron progenitors and, finally, into mature podocytes. After differentiation, cells expressed the main podocyte markers, such as synaptopodin, WT1, α-Actinin-4, P-cadherin and nephrin at the protein and mRNA level, and showed the low proliferation rate typical of mature podocytes. Exposure to Angiotensin II significantly decreased the expression of podocyte genes and cells underwent cytoskeleton rearrangement. Cells were able to internalize albumin and self-assembled into chimeric 3D structures in combination with dissociated embryonic mouse kidney cells. Overall, these findings demonstrate the establishment of a robust protocol that, mimicking developmental stages, makes it possible to derive functional podocytes in vitro.

•

Human iPSC differentiation into podocytes recapitulates kidney developmental stages.

•

The differentiation protocol is reproducible and highly efficient.

•

The generated podocytes reflect primary cell behaviour and are functional.

TBX3 Knockdown Decreases Reprogramming Efficiency of Human Cells

TBX3 is a member of the T-box transcription factor family and is involved in the core pluripotency network. Despite this role in the pluripotency network, its contribution to the reprogramming process during the generation of human induced pluripotent stem cells remains elusive. In this respect, we performed reprogramming experiments applying TBX3 knockdown in human fibroblasts and keratinocytes. Knockdown of TBX3 in both somatic cell types decreased the reprogramming efficiencies in comparison to control cells but with unchanged reprogramming kinetics. The resulting iPSCs were indistinguishable from control cells and displayed a normal in vitro differentiation capacity by generating cells of all three germ layers comparable to the controls.

Wild-type macrophages reverse disease in heme oxygenase 1-deficient mice

Loss-of-function mutation in the heme oxygenase 1 (Hmox1) gene causes a rare and lethal disease in children, characterized by severe anemia and intravascular hemolysis, with damage to endothelia and kidneys. Previously, we found that macrophages engaged in recycling of red cells were depleted from the tissues of Hmox1(-/-) mice, which resulted in intravascular hemolysis and severe damage to the endothelial system, kidneys, and other organs. Here, we report that subablative bone marrow transplantation (BMT) has a curative effect for disease in Hmox1(-/-) animals as a result of restoration of heme recycling by repopulation of the tissues with wild-type macrophages. Although engraftment was transient, BMT reversed anemia, normalized blood chemistries and iron metabolism parameters, and prevented renal damage. The largest proportion of donor-derived cells was observed in the livers of transplanted animals. These cells, identified as Kupffer cells with high levels of Hmox1 expression, persisted months after transient engraftment of the donor bone marrow and were responsible for the full restoration of heme-recycling ability in Hmox1(-/-) mice and reversing Hmox1-deficient phenotype. Our findings suggest that BMT or the development of specific cell therapies to repopulate patients' tissues with wild-type or reengineered macrophages represent promising approaches for HMOX1 deficiency treatment in humans.

Tissue engineering approaches to cell-based type 1 diabetes therapy

Type 1 diabetes mellitus is an autoimmune disease resulting from the destruction of insulin-producing pancreatic β-cells. Cell-based therapies, involving the transplantation of functional β-cells into diabetic patients, have been explored as a potential long-term treatment for this condition; however, success is limited. A tissue engineering approach of culturing insulin-producing cells with extracellular matrix (ECM) molecules in three-dimensional (3D) constructs has the potential to enhance the efficacy of cell-based therapies for diabetes. When cultured in 3D environments, insulin-producing cells are often more viable and secrete more insulin than those in two dimensions. The addition of ECM molecules to the culture environments, depending on the specific type of molecule, can further enhance the viability and insulin secretion. This review addresses the different cell sources that can be utilized as β-cell replacements, the essential ECM molecules for the survival of these cells, and the 3D culture techniques that have been used to benefit cell function.

Human and murine very small embryonic-like cells represent multipotent tissue progenitors, in vitro and in vivo

The purpose of this study was to determine the lineage progression of human and murine very small embryonic-like (HuVSEL or MuVSEL) cells in vitro and in vivo. In vitro, HuVSEL and MuVSEL cells differentiated into cells of all three embryonic germ layers. HuVSEL cells produced robust mineralized tissue of human origin compared with controls in calvarial defects. Immunohistochemistry demonstrated that the HuVSEL cells gave rise to neurons, adipocytes, chondrocytes, and osteoblasts within the calvarial defects. MuVSEL cells were also able to differentiate into similar lineages. First round serial transplants of MuVSEL cells into irradiated osseous sites demonstrated that ∼60% of the cells maintained their VSEL cell phenotype while other cells differentiated into multiple tissues at 3 months. Secondary transplants did not identify donor VSEL cells, suggesting limited self renewal but did demonstrate VSEL cell derivatives in situ for up to 1 year. At no point were teratomas identified. These studies show that VSEL cells produce multiple cellular structures in vivo and in vitro and lay the foundation for future cell-based regenerative therapies for osseous, neural, and connective tissue disorders.

Generation of human induced pluripotent stem cells using epigenetic regulators reveals a germ cell-like identity in partially reprogrammed colonies

Previous studies have shown that induced pluripotent stem cells (iPSCs) can be derived from fibroblasts by ectopic expression of four transcription factors, OCT4, SOX2, KLF4 and c-MYC using various methods. More recent studies have focused on identifying alternative approaches and factors that can be used to increase reprogramming efficiency of fibroblasts to pluripotency. Here, we use nucleofection, morpholino technologies and novel epigenetic factors, which were chosen based on their expression profile in human embryos, fibroblasts and undifferentiated/differentiated human embryonic stem cells (hESCs) and conventionally generated iPSCs, to reprogram human fibroblasts into iPSCs. By over expressing DNMT3B, AURKB, PRMT5 and/or silencing SETD7 in human fibroblasts with and without NANOG, hTERT and/or SV40 overexpression, we observed the formation of colonies resembling iPSCs that were positive for certain pluripotency markers, but exhibited minimal proliferation. More importantly, we also demonstrate that these partially-reprogrammed colonies express high levels of early to mid germ cell-specific genes regardless of the transfection approach, which suggests conversion to a germ cell-like identity is associated with early reprogramming. These findings may provide an additional means to evaluate human germ cell differentiation in vitro, particularly in the context of pluripotent stem cell-derived germ cell development, and contribute to our understanding of the epigenetic requirements of the reprogramming process.

Promising perspectives towards regrowing a human arm

Despite the great enthusiasm about tissue engineering during the 1980s and the many significant basic observations made since then, the clinical application of tissue-engineered products has been limited. However, the prospect of creating new human tissues and organs is still exciting and continues to be a significant challenge for scientists and clinicians. A human arm is an extremely complicated biological construction. Considering regrowing a human arm requires asking about the current state-of-the-art of tissue engineering and the real capabilities that it may offer within a realistic time horizon. This work briefly addresses the state-of-the-art in the fields of cells and scaffolds that have high regenerative potential. Additional tools that are required to reconstruct more complex parts of the body, such as a human arm, seem achievable with the already available more sophisticated culture systems including three-dimensional organization, dynamic conditions and co-cultures. Finally, we present results on cell differentiation and cell and tissue maturation in culture when cells are exposed to mechanical forces. We postulate that in the foreseeable future even such complicated structures such as a human arm will be regrown in full in vitro under the conditions of a mechanically controlled co-culture system.

The tumourigenicity of iPS cells and their differentiated derivates

Induced pluripotent stem cell (iPSC) provides a promising seeding cell for regenerative medicine. However, iPSC has the potential to form teratomas after transplantation. Therefore, it is necessary to evaluate the tumorigenic risks of iPSC and all its differentiated derivates prior to use in a clinical setting. Here, murine iPSCs were transduced with dual reporter gene consisting of monomeric red fluorescent protein (mRFP) and firefly luciferase (Fluc). Undifferentiated iPSCs, iPSC derivates from induced differentiation (iPSC-derivates), iPSC-derivated cardiomyocyte (iPSC-CMs) were subcutaneously injected into the back of nude mice. Non-invasive bioluminescence imaging (BLI) was longitudinally performed at day 1, 7, 14 and 28 after transplantation to track the survival and proliferation of transplanted cells. At day 28, mice were killed and grafts were explanted to detect teratoma formation. The results demonstrated that transplanted iPSCs, iPSC-derivates and iPSC-CMs survived in receipts. Both iPSCs and iPSC-derivates proliferated dramatically after transplantation, while only slight increase in BLI signals was observed in iPSC-CM transplanted mice. At day 28, teratomas were detected in both iPSCs and iPSC-derivates transplanted mice, but not in iPSC-CM transplanted ones. In vitro study showed the long-term existence of pluripotent cells during iPSC differentiation. Furthermore, when these cells were passaged in feeder layers as undifferentiated iPSCs, they would recover iPSC-like colonies, indicating the cause for differentiated iPSC's tumourigenicity. Our study indicates that exclusion of tumorigenic cells by screening in addition to lineage-specific differentiation is necessary prior to therapeutic use of iPSCs.