Describing the Stem Cell Potency: The Various Methods of Functional Assessment and In silico Diagnostics

Stem cell and exosome therapies for regenerating damaged myocardium in heart failure

Finding novel treatments for cardiovascular diseases (CVDs) is a hot topic in medicine; cell-based therapies have reported promising news for controlling dangerous complications of heart disease such as myocardial infarction (MI) and heart failure (HF). Various progenitor/stem cells were tested in various in-vivo, in-vitro, and clinical studies for regeneration or repairing the injured tissue in the myocardial to accelerate the healing. Fetal, adult, embryonic, and induced pluripotent stem cells (iPSC) have revealed the proper potency for cardiac tissue repair. As an essential communicator among cells, exosomes with specific contacts (proteins, lncRNAs, and miRNAs) greatly promote cardiac rehabilitation. Interestingly, stem cell-derived exosomes have more efficiency than stem cell transplantation. Therefore, stem cells induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), cardiac stem cells (CDC), and skeletal myoblasts) and their-derived exosomes will probably be considered an alternative therapy for CVDs remedy. In addition, stem cell-derived exosomes have been used in the diagnosis/prognosis of heart diseases. In this review, we explained the advances of stem cells/exosome-based treatment, their beneficial effects, and underlying mechanisms, which will present new insights in the clinical field in the future.

Stem Cells and Acellular Preparations in Bone Regeneration/Fracture Healing: Current Therapies and Future Directions

Bone/fracture healing is a complex process with different steps and four basic tissue layers being affected: cortical bone, periosteum, fascial tissue surrounding the fracture, and bone marrow. Stem cells and their derivatives, including embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, hematopoietic stem cells, skeletal stem cells, and multipotent stem cells, can function to artificially introduce highly regenerative cells into decrepit biological tissues and augment the healing process at the tissue level. Stem cells are molecularly and functionally indistinguishable from standard human tissues. The widespread appeal of stem cell therapy lies in its potential benefits as a therapeutic technology that, if harnessed, can be applied in clinical settings. This review aims to establish the molecular pathophysiology of bone healing and the current stem cell interventions that disrupt or augment the bone healing process and, finally, considers the future direction/therapeutic options related to stem cells and bone healing.

Age-Related Alterations in Mesenchymal Stem Cell Function: Understanding Mechanisms and Seeking Opportunities to Bypass the Cellular Aging

Undoubtedly, mesenchymal stem cells (MSCs) are the most common cell therapy candidates in clinical research and therapy. They not only exert considerable therapeutic effects to alleviate inflammation and promote regeneration, but also show low-immunogenicity properties, which ensure their safety following allogeneic transplantation. Thanks to the necessity of providing a sufficient number of MSCs to achieve clinically efficient outcomes, prolonged in vitro cultivation is indisputable. However, either following long-term in vitro expansion or aging in elderly individuals, MSCs face cellular senescence. Senescent MSCs undergo an impairment in their function and therapeutic capacities and secrete degenerative factors which negatively affect young MSCs. To this end, designing novel investigations to further elucidate cellular senescence and to pave the way toward finding new strategies to reverse senescence is highly demanded. In this review, we will concisely discuss current progress on the detailed mechanisms of MSC senescence and various inflicted changes following aging in MSC. We will also shed light on the examined strategies underlying monitoring and reversing senescence in MSCs to bypass the comprised therapeutic efficacy of the senescent MSCs.

Advances in Genetic Reprogramming: Prospects from Developmental Biology to Regenerative Medicine

The foundations of cell reprogramming were laid by Yamanaka and co-workers, who showed that somatic cells can be reprogrammed into pluripotent cells (induced pluripotency). Since this discovery, the field of regenerative medicine has seen advancements. For example, because they can differentiate into multiple cell types, pluripotent stem cells are considered vital components in regenerative medicine aimed at the functional restoration of damaged tissue. Despite years of research, both replacement and restoration of failed organs/ tissues have remained elusive scientific feats. However, with the inception of cell engineering and nuclear reprogramming, useful solutions have been identified to counter the need for compatible and sustainable organs. By combining the science underlying genetic engineering and nuclear reprogramming with regenerative medicine, scientists have engineered cells to make gene and stem cell therapies applicable and effective. These approaches have enabled the targeting of various pathways to reprogramme cells, i.e., make them behave in beneficial ways in a patient-specific manner. Technological advancements have clearly supported the concept and realization of regenerative medicine. Genetic engineering is used for tissue engineering and nuclear reprogramming and has led to advances in regenerative medicine. Targeted therapies and replacement of traumatized , damaged, or aged organs can be realized through genetic engineering. Furthermore, the success of these therapies has been validated through thousands of clinical trials. Scientists are currently evaluating induced tissue-specific stem cells (iTSCs), which may lead to tumour-free applications of pluripotency induction. In this review, we present state-of-the-art genetic engineering that has been used in regenerative medicine. We also focus on ways that genetic engineering and nuclear reprogramming have transformed regenerative medicine and have become unique therapeutic niches.

Autologous Stem Cell Transplant in Hodgkin's and Non-Hodgkin's Lymphoma, Multiple Myeloma, and AL Amyloidosis

Human body cells are stem cell (SC) derivatives originating from bone marrow. Their special characteristics include their capacity to support the formation and self-repair of the cells. Cancer cells multiply uncontrollably and invade healthy tissues, making stem cell transplants a viable option for cancer patients undergoing high-dose chemotherapy (HDC). When chemotherapy is used at very high doses to eradicate all cancer cells from aggressive tumors, blood-forming cells and leukocytes are either completely or partially destroyed. Autologous stem cell transplantation (ASCT) is necessary for patients in those circumstances. The patients who undergo autologous transplants receive their own stem cells (SCs). The transplanted stem cells first come into contact with the bone marrow and then undergo engraftment, before differentiating into blood cells. ASCT is one of the most significant and innovative strategies for treating diseases. Here we focus on the treatment of Hodgkin's lymphoma, non-Hodgkin's lymphoma, multiple myeloma, and AL amyloidosis, using ASCT. This review provides a comprehensive picture of the effectiveness and the safety of ASCT as a therapeutic approach for these diseases, based on the currently available evidence.

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

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

Mesenchymal stem cell-derived exosomes as new tools for delivery of miRNAs in the treatment of cancer

Although ongoing medical research is working to find a cure for a variety of cancers, it continues to be one of the major causes of death worldwide. Chemotherapy and immunotherapy, as well as surgical intervention and radiation therapy, are critical components of cancer treatment. Most anti-cancer drugs are given systemically and distribute not just to tumor tissues but also to normal tissues, where they may cause side effects. Furthermore, because anti-cancer drugs have a low delivery efficiency, some tumors do not respond to them. As a result, tumor-targeted drug delivery is critical for improving the safety and efficacy of anti-cancer treatment. Exosomes are microscopic extracellular vesicles that cells produce to communicate with one another. MicroRNA (miRNA), long non-coding RNA (lncRNA), small interfering RNA (siRNA), DNA, protein, and lipids are among the therapeutic cargos found in exosomes. Recently, several studies have focused on miRNAs as a potential therapeutic element for the treatment of cancer. Mesenchymal stem cells (MSC) have been known to have angiogenic, anti-apoptotic, anti-inflammatory and immunomodulatory effects. Exosomes derived from MSCs are gaining popularity as a non-cellular alternative to MSC-based therapy, as this method avoids unwanted lineage differentiation. Therefore more research have focused on transferring miRNAs to mesenchymal stem cells (MSC) and targeting miRNA-loaded exosomes to cancer cells. Here, we initially gave an overview of the characteristics and potentials of MSC as well as the use of MSC-derived exosomes in cancer therapy. Finally, we emphasized the utilization of MSC-derived exosomes for miRNA delivery in the treatment of cancer.

Solute Carrier Nucleoside Transporters in Hematopoiesis and Hematological Drug Toxicities: A Perspective

Simple Summary

Anticancer nucleoside analogs are promising treatments that often result in damaging toxicities and therefore ineffective treatment. Mechanisms of this are not well-researched, but cellular nucleoside transport research in mice might provide additional insight given transport’s role in mammalian hematopoiesis. Cellular nucleoside transport is a notable component of mammalian hematopoiesis due to how mutations within it relate to hematological abnormities. This review encompasses nucleoside transporters, focusing on their inherent properties, hematopoietic role, and their interplay in nucleoside drug treatment side effects. We then propose potential mechanisms to explain nucleoside transport involvement in blood disorders. Finally, we point out and advocate for future research areas that would improve therapeutic outcomes for patients taking nucleoside analog therapies.

Abstract

Anticancer nucleoside analogs produce adverse, and at times, dose-limiting hematological toxicities that can compromise treatment efficacy, yet the mechanisms of such toxicities are poorly understood. Recently, cellular nucleoside transport has been implicated in normal blood cell formation with studies from nucleoside transporter-deficient mice providing additional insights into the regulation of mammalian hematopoiesis. Furthermore, several idiopathic human genetic disorders have revealed nucleoside transport as an important component of mammalian hematopoiesis because mutations in individual nucleoside transporter genes are linked to various hematological abnormalities, including anemia. Here, we review recent developments in nucleoside transporters, including their transport characteristics, their role in the regulation of hematopoiesis, and their potential involvement in the occurrence of adverse hematological side effects due to nucleoside drug treatment. Furthermore, we discuss the putative mechanisms by which aberrant nucleoside transport may contribute to hematological abnormalities and identify the knowledge gaps where future research may positively impact treatment outcomes for patients undergoing various nucleoside analog therapies.

Advances in hPSC expansion towards therapeutic entities: A review

For use in regenerative medicine, large‐scale manufacturing of human pluripotent stem cells (hPSCs) under current good manufacturing practice (cGMPs) is required. Much progress has been made since culturing under static two‐dimensional (2D) conditions on feeders, including feeder‐free cultures, conditioned and xeno‐free media, and three‐dimensional (3D) dynamic suspension expansion. With the advent of horizontal‐blade and vertical‐wheel bioreactors, scale‐out for large‐scale production of differentiated hPSCs became possible; control of aggregate size, shear stress, fluid hydrodynamics, batch‐feeding strategies, and other process parameters became a reality. Moving from substantially manipulated processes (i.e., 2D) to more automated ones allows easer compliance to current good manufacturing practices (cGMPs), and thus easier regulatory approval. Here, we review the current advances in the field of hPSC culturing, advantages, and challenges in bioreactor use, and regulatory areas of concern with respect to these advances. Manufacturing trends to reduce risk and streamline large‐scale manufacturing will bring about easier, faster regulatory approval for clinical applications.

Stem cells technology as a platform for generating reproductive system organoids and treatment of infertility-related diseases

In recent years, stem cells have known as a helpful biological tool for the accurate diagnosis, treatment and recognition of diseases. Using stem cells as biomarkers have presented high potential in the early detection of many diseases. Another advancement in stem cell technology includes stem cell derived organoids model that could be a promising platform for diagnosis and modeling different diseases. Furthermore, therapeutic capabilities of stem cell therapy have increased hope in the face of different disability managements. All of these technologies are also widely used in reproductive related diseases especially in today's world that many couples encounter infertility problems. However, with the aid of numerous improvements in the treatment of infertility, over 80% of couples who dreamed of having children could now have children. Due to the fact that infertility has many negative effects on personal and social lives of young couples, many researchers have focused on the treatment of male and female reproductive system abnormalities with different types of stem cells, including embryonic stem cells, bone marrow mesenchymal stem cells (MSCs), and umbilical cord-derived MSCs. Also, design and formation of reproductive system organoids provide a fascinating window into disease modeling, drug screening, personalized therapy, and regeneration medicine. Utilizing these techniques to study, model and treat the infertility-related diseases has drawn attention of many scientists. This review explains different applications of stem cells in generating reproductive system organoids and stem cell-based therapies for male and female infertility related diseases treatment.

Genome Editing and Human Pluripotent Stem Cell Technologies for in vitro Monogenic Diabetes Modeling

Diabetes is a metabolic disease characterized by chronic hyperglycemia. Polygenic diabetes, which encompasses type-1 and type-2 diabetes, is the most prevalent kind of diabetes and is caused by a combination of different genetic and environmental factors, whereas rare phenotype monogenic diabetes is caused by a single gene mutation. Monogenic diabetes includes Neonatal diabetes mellitus and Maturity-onset diabetes of the young. The majority of our current knowledge about the pathogenesis of diabetes stems from studies done on animal models. However, the genetic difference between these creatures and humans makes it difficult to mimic human clinical pathophysiology, limiting their value in modeling key aspects of human disease. Human pluripotent stem cell technologies combined with genome editing techniques have been shown to be better alternatives for creating in vitro models that can provide crucial knowledge about disease etiology. This review paper addresses genome editing and human pluripotent stem cell technologies for in vitro monogenic diabetes modeling.

Cell Therapy: Types, Regulation, and Clinical Benefits

Cell therapy practices date back to the 19th century and continue to expand on investigational and investment grounds. Cell therapy includes stem cell- and non-stem cell-based, unicellular and multicellular therapies, with different immunophenotypic profiles, isolation techniques, mechanisms of action, and regulatory levels. Following the steps of their predecessor cell therapies that have become established or commercialized, investigational and premarket approval-exempt cell therapies continue to provide patients with promising therapeutic benefits in different disease areas. In this review article, we delineate the vast types of cell therapy, including stem cell-based and non-stem cell-based cell therapies, and create the first-in-literature compilation of the different "multicellular" therapies used in clinical settings. Besides providing the nuts and bolts of FDA policies regulating their use, we discuss the benefits of cell therapies reported in 3 therapeutic areas-regenerative medicine, immune diseases, and cancer. Finally, we contemplate the recent attention shift toward combined therapy approaches, highlighting the factors that render multicellular therapies a more attractive option than their unicellular counterparts.

Neonatal Porcine Germ Cells Dedifferentiate and Display Osteogenic and Pluripotency Properties

Gonocytes are progenitors of spermatogonial stem cells in the neonatal testis. We have previously shown that upon culturing, neonatal porcine gonocytes and their colonies express germ cell and pluripotency markers. The objectives of present study were to investigate in vitro trans-differentiation potential of porcine gonocytes and their colonies into cells from three germinal layers, and to assess pluripotency of cultured gonocytes/colonies in vivo. For osteogenic and tri-lineage differentiation, cells were incubated in regular culture media for 14 and 28 days, respectively. Cells were cultured for an additional 14 days for osteogenic differentiation or 7 days for differentiation into derivates of the three germinal layers. Osteogenic differentiation of cells and colonies was verified by Alizarin Red S staining and tri-lineage differentiation was confirmed using immunofluorescence and gene expression analyses. Furthermore, upon implantation into recipient mice, the cultured cells/colonies developed teratomas expressing markers of all three germinal layers. Successful osteogenic differentiation from porcine germ cells has important implications for bone regeneration and matrix formation studies. Hence, gonocytes emerge as a promising source of adult pluripotent stem cells due to the ability to differentiate into all germinal layers without typical biosafety risks associated with viral vectors or ethical implications.

An overview of mesenchymal stem cells and their potential therapeutic benefits in cancer therapy

There has been increased interest in using stem cells for regenerative medicine and cancer therapy in the past decade. Mesenchymal stem cells (MSCs) are among the most studied stem cells due to their unique characteristics, such as self-renewal and developmental potency to differentiate into numerous cell types. MSC use has fewer ethical challenges compared with other types of stem cells. Although a number of studies have reported the beneficial effects of MSC-based therapies in treating various diseases, their contribution to cancer therapy remains controversial. The behaviour of MSCs is determined by the interaction between intrinsic transcriptional genes and extrinsic environmental factors. Numerous studies continue to emerge, as there is no denying the potential of MSCs to treat a wide variety of human afflictions. Therefore, the present review article provided an overview of MSCs and their differences compared with embryonic stem cells, and described the molecular mechanisms involved in maintaining their stemness. In addition, the article examined the therapeutic application of stem cells in the field of cancer. The present article also discussed the current divergent roles of MSCs in cancer therapy and the future potential in this field.

Stem cells' centrosomes: How can organelles identified 130 years ago contribute to the future of regenerative medicine?

At the core of regenerative medicine lies the expectation of repair or replacement of damaged tissues or whole organs. Donor scarcity and transplant rejection are major obstacles, and exactly the obstacles that stem cell-based therapy promises to overcome. These therapies demand a comprehensive understanding of the asymmetric division of stem cells, i.e. their ability to produce cells with identical potency or differentiated cells. It is believed that with better understanding, researchers will be able to direct stem cell differentiation. Here, we describe extraordinary advances in manipulating stem cell fate that show that we need to focus on the centrosome and the centrosome-derived primary cilium. This belief comes from the fact that this organelle is the vehicle that coordinates the asymmetric division of stem cells. This is supported by studies that report the significant role of the centrosome/cilium in orchestrating signaling pathways that dictate stem cell fate. We anticipate that there is sufficient evidence to place this organelle at the center of efforts that will shape the future of regenerative medicine.

Ribosome-Induced Cellular Multipotency, an Emerging Avenue in Cell Fate Reversal

The ribosome, which is present in all three domains of life, plays a well-established, critical role in the translation process by decoding messenger RNA into protein. Ribosomal proteins, in contrast, appear to play non-translational roles in growth, differentiation, and disease. We recently discovered that ribosomes are involved in reverting cellular potency to a multipotent state. Ribosomal incorporation (the uptake of free ribosome by living cells) can direct the fate of both somatic and cancer cells into multipotency, allowing them to switch cell lineage. During this process, both types of cells experienced cell-cycle arrest and cellular stress while remaining multipotent. This review provides a molecular perspective on current insights into ribosome-induced multipotency and sheds light on how a common stress-associated mechanism may be involved. We also discuss the impact of this phenomenon on cancer cell reprogramming and its potential in cancer therapy.

2D biointerfaces to study stem cell-ligand interactions

Stem cells have great potential in the field of tissue engineering and regenerative medicine due to their inherent regenerative capabilities. However, an ongoing challenge within their clinical translation is to elicit or predict the desired stem cell behavior once transplanted. Stem cell behavior and function are regulated by their interaction with biophysical and biochemical signals present in their natural environment (i.e., stem cell niches). To increase our understanding about the interplay between stem cells and their resident microenvironments, biointerfaces have been developed as tools to study how these substrates can affect stem cell behaviors. This article aims to review recent developments on fabricating cell-instructive interfaces to control cell adhesion processes towards directing stem cell behavior. After an introduction on stem cells and their natural environment, static surfaces exhibiting predefined biochemical signals to probe the effect of chemical features on stem cell behaviors are discussed. In the third section, we discuss more complex dynamic platforms able to display biochemical cues with spatiotemporal control using on-off ligand display, reversible ligand display, and ligand mobility. In the last part of the review, we provide the reader with an outlook on future designs of biointerfaces. STATEMENT OF SIGNIFICANCE: Stem cells have great potential as treatments for many degenerative disorders prevalent in our aging societies. However, an ongoing challenge within their clinical translation is to promote stem cell mediated regeneration once they are transplanted in the body. Stem cells reside within our bodies where their behavior and function are regulated by interactions with their natural environment called the stem cell niche. To increase our understanding about the interplay between stem cells and their niche, 2D materials have been developed as tools to study how specific signals can affect stem cell behaviors. This article aims to review recent developments on fabricating cell-instructive interfaces to control cell adhesion processes towards directing stem cell behavior.

Effect of Polymeric Matrix Stiffness on Osteogenic Differentiation of Mesenchymal Stem/Progenitor Cells: Concise Review

Mesenchymal stem/progenitor cells (MSCs) have a multi-differentiation potential into specialized cell types, with remarkable regenerative and therapeutic results. Several factors could trigger the differentiation of MSCs into specific lineages, among them the biophysical and chemical characteristics of the extracellular matrix (ECM), including its stiffness, composition, topography, and mechanical properties. MSCs can sense and assess the stiffness of extracellular substrates through the process of mechanotransduction. Through this process, the extracellular matrix can govern and direct MSCs' lineage commitment through complex intracellular pathways. Hence, various biomimetic natural and synthetic polymeric matrices of tunable stiffness were developed and further investigated to mimic the MSCs' native tissues. Customizing scaffold materials to mimic cells' natural environment is of utmost importance during the process of tissue engineering. This review aims to highlight the regulatory role of matrix stiffness in directing the osteogenic differentiation of MSCs, addressing how MSCs sense and respond to their ECM, in addition to listing different polymeric biomaterials and methods used to alter their stiffness to dictate MSCs' differentiation towards the osteogenic lineage.

Stem Cell-Derived Exosomes Potential Therapeutic Roles in Cardiovascular Diseases

Owing to myocardial abnormalities, cardiac ailments are considered to be the major cause of morbidity and mortality worldwide. According to a recent study, membranous vesicles that are produced naturally, termed as "exosomes", have emerged as the potential candidate in the field of cardiac regenerative medicine. A wide spectrum of stem cells has also been investigated in the treatment of cardiovascular diseases (CVD). Exosomes obtained from the stem cells are found to be cardioprotective and offer great hope in the treatment of CVD. The basic nature of exosomes is to deal with the intracellular delivery of both proteins and nucleic acids. This activity of exosomes helps us to rely on them as the attractive pharmaceutical delivery agents. Most importantly, exosomes derived from microRNAs (miRNAs) hold great promise in assessing the risk of CVD, as they serve as notable biomarkers of the disease. Exosomes are small, less immunogenic, and lack toxicity. These nanovesicles harbor immense potential as a therapeutic entity and would provide fruitful benefits if consequential research were focused on their upbringing and development as a useful diagnostic and therapeutic tool in the field of medicine.

Building Pluripotency Identity in the Early Embryo and Derived Stem Cells

The fusion of two highly differentiated cells, an oocyte with a spermatozoon, gives rise to the zygote, a single totipotent cell, which has the capability to develop into a complete, fully functional organism. Then, as development proceeds, a series of programmed cell divisions occur whereby the arising cells progressively acquire their own cellular and molecular identity, and totipotency narrows until when pluripotency is achieved. The path towards pluripotency involves transcriptome modulation, remodeling of the chromatin epigenetic landscape to which external modulators contribute. Both human and mouse embryos are a source of different types of pluripotent stem cells whose characteristics can be captured and maintained in vitro. The main aim of this review is to address the cellular properties and the molecular signature of the emerging cells during mouse and human early development, highlighting similarities and differences between the two species and between the embryos and their cognate stem cells.

To Better Generate Organoids, What Can We Learn From Teratomas?

The genomic profile of animal models is not completely matched with the genomic profile of humans, and 2D cultures do not represent the cellular heterogeneity and tissue architecture found in tissues of their origin. Derived from 3D culture systems, organoids establish a crucial bridge between 2D cell cultures and in vivo animal models. Organoids have wide and promising applications in developmental research, disease modeling, drug screening, precision therapy, and regenerative medicine. However, current organoids represent only single or partial components of a tissue, which lack blood vessels, native microenvironment, communication with near tissues, and a continuous dorsal-ventral axis within 3D culture systems. Although efforts have been made to solve these problems, unfortunately, there is no ideal method. Teratoma, which has been frequently studied in pathological conditions, was recently discovered as a new in vivo model for developmental studies. In contrast to organoids, teratomas have vascularized 3D structures and regions of complex tissue-like organization. Studies have demonstrated that teratomas can be used to mimic multilineage human development, enrich specific somatic progenitor/stem cells, and even generate brain organoids. These results provide unique opportunities to promote our understanding of the vascularization and maturation of organoids. In this review, we first summarize the basic characteristics, applications, and limitations of both organoids and teratomas and further discuss the possibility that in vivo teratoma systems can be used to promote the vascularization and maturation of organoids within an in vitro 3D culture system.

Patentability challenges associated with emerging pharmaceutical technologies

According to the recent patent filing trends, it has been observed that certain pharmaceutical technologies are more popular than others and are commonly referred to as emerging technologies. The emerging technologies in the pharmaceutical sector include artificial intelligence, big data and certain advanced biological therapies such as personalized medicine and stem cell therapy. These trends have various applications in the medicine and healthcare industry. Since these technologies are relatively new and each of them is very unique in its own way, current patent laws are inadequate to deal with the complex challenges associated with them. A brief analysis of the challenges associated with these emerging technologies and their applications is discussed in this paper.

Stem Cell-Derived Exosomes: a New Strategy of Neurodegenerative Disease Treatment

Short-term symptomatic treatment and dose-dependent side effects of pharmacological treatment for neurodegenerative diseases have forced the medical community to seek an effective treatment for this serious global health threat. Therapeutic potential of stem cell for treatment of neurodegenerative disorders was identified in 1980 when fetal nerve tissue was used to treat Parkinson's disease (PD). Then, extensive studies have been conducted to develop this treatment strategy for neurological disease therapy. Today, stem cells and their secretion are well-known as a therapeutic environment for the treatment of neurodegenerative diseases. This new paradigm has demonstrated special characteristics related to this treatment, including neuroprotective and neurodegeneration, remyelination, reduction of neural inflammation, and recovery of function after induced injury. However, the exact mechanism of stem cells in repairing nerve damage is not yet clear; exosomes derived from them, an important part of their secretion, are introduced as responsible for an important part of such effects. Numerous studies over the past few decades have evaluated the therapeutic potential of exosomes in the treatment of various neurological diseases. In this review, after recalling the features and therapeutic history, we will discuss the latest stem cell-derived exosome-based therapies for these diseases.

Stem cell therapy for heart failure: Medical breakthrough, or dead end?

Heart failure continues to be one of the leading causes of morbidity and mortality worldwide. Myocardial infarction is the primary causative agent of chronic heart failure resulting in cardiomyocyte necrosis and the subsequent formation of fibrotic scar tissue. Current pharmacological and non-pharmacological therapies focus on managing symptoms of heart failure yet remain unable to reverse the underlying pathology. Heart transplantation usually cannot be relied on, as there is a major discrepancy between the availability of donors and recipients. As a result, heart failure carries a poor prognosis and high mortality rate. As the heart lacks significant endogenous regeneration potential, novel therapeutic approaches have incorporated the use of stem cells as a vehicle to treat heart failure as they possess the ability to self-renew and differentiate into multiple cell lineages and tissues. This review will discuss past, present, and future clinical trials, factors that influence stem cell therapy outcomes as well as ethical and safety considerations. Preclinical and clinical studies have shown a wide spectrum of outcomes when applying stem cells to improve cardiac function. This may reflect the infancy of clinical trials and the limited knowledge on the optimal cell type, dosing, route of administration, patient parameters and other important variables that contribute to successful stem cell therapy. Nonetheless, the field of stem cell therapeutics continues to advance at an unprecedented pace. We remain cautiously optimistic that stem cells will play a role in heart failure management in years to come.

Combination of platelet rich plasma and stromal vascular fraction on the level of vascular endothelial growth factor in rat subjects experiencing deep dermal burn injury

Background

The healing process of burns includes coagulation, inflammation, and remodeling. Vascular endothelial growth factor (VEGF) is involved throughout this healing process. Stem cells from the platelet-rich plasma (PRP) with stromal vascular fraction (SVF) can increase concentrations of growth factors, including VEGF. This is expected to accelerate burn healing. The aim of this study was to determine the effect of a combination of PRP and SVF on VEGF levels in a rats model of deep dermal burn wound healing.

Materials and methods

This is an experimental research study in rats using a post-test control group design with 4 groups: A) control, B) Vaseline, C) topical PRP and SVF, and D) PRP and SVF injection. Burn wounds were induced according to the modified Guo method.

Results

In a rats model of deep dermal wound healing, topical Vaseline significantly increased serum VEGF compared to control. Topical application and injection of stem cells also significantly increased serum VEGF compared to control and Vaseline. The VEGF concentration was significantly higher following injection of PRP and SVF, suggesting that the injection route is more effective at increasing VEGF levels compared to the topical application of stem cells.

Conclusion

The combination of PRP and SVF, either by injection or topical application, can increase VEGF levels during the healing process from deep dermal burns.

•

Stem cells can increase concentrations of growth factors.

•

Topical application and injection of stem cells significantly increased serum VEGF compared to control.

•

The VEGF concentration was significantly higher following injection of PRP and SVFs.

•

The injection route of stem cells is more effective at increasing VEGF levels compared to the topical application.

Stem Cell Therapy in the Management of Fracture Non-Union - Evaluating Cellular Mechanisms and Clinical Progress

Bone, as a physiological and anatomical construct, displays remarkable intrinsic healing capacity. The overwhelming majority of fractures will heal satisfactorily, if aligned anatomically, compressed and immobilised appropriately. Of the 10% of fractures that do not heal, even under ideal mechanical and biological conditions, further consideration must be given to augment bone healing. Management strategies for non-union pose a significant clinical challenge to the practicing orthopaedic surgeon. Stem cell therapy is beginning to demonstrate significant potential for augmented bone repair in the context of non-union. This review attempts to contextualise the function of stem cells within this clinical setting, reviewing the relevant cellular mechanisms and clinical applications. From evaluating the literature base, there is a lack of high-quality evidence examining the role of mesenchymal stem cells (MSCs) within this research focus. Appropriately designed randomised controlled trials are required to evaluate this research area further, with a view to guiding future treatment options for the practicing orthopaedic surgeon.

A Review of Recent Advances in 3D Bioprinting With an Eye on Future Regenerative Therapies in Veterinary Medicine

3D bioprinting is a rapidly evolving industry that has been utilized for a variety of biomedical applications. It differs from traditional 3D printing in that it utilizes bioinks comprised of cells and other biomaterials to allow for the generation of complex functional tissues. Bioprinting involves computational modeling, bioink preparation, bioink deposition, and subsequent maturation of printed products; it is an intricate process where bioink composition, bioprinting approach, and bioprinter type must be considered during construct development. This technology has already found success in human studies, where a variety of functional tissues have been generated for both in vitro and in vivo applications. Although the main driving force behind innovation in 3D bioprinting has been utility in human medicine, recent efforts investigating its veterinary application have begun to emerge. To date, 3D bioprinting has been utilized to create bone, cardiovascular, cartilage, corneal and neural constructs in animal species. Furthermore, the use of animal-derived cells and various animal models in human research have provided additional information regarding its capacity for veterinary translation. While these studies have produced some promising results, technological limitations as well as ethical and regulatory challenges have impeded clinical acceptance. This article reviews the current understanding of 3D bioprinting technology and its recent advancements with a focus on recent successes and future translation in veterinary medicine.

Comparative hematopoiesis and signal transduction in model organisms

Hematopoiesis is a continuous phenomenon involving the formation of hematopoietic stem cells (HSCs) giving rise to diverse functional blood cells. This developmental process of hematopoiesis is evolutionarily conserved, yet comparably different in various model organisms. Vertebrate HSCs give rise to all types of mature cells of both the myeloid and the lymphoid lineages sequentially colonizing in different anatomical tissues. Signal transduction in HSCs facilitates their potency and specifies branching of lineages. Understanding the hematopoietic signaling pathways is crucial to gain insights into their deregulation in several blood-related disorders. The focus of the review is on hematopoiesis corresponding to different model organisms and pivotal role of indispensable hematopoietic pathways. We summarize and discuss the fundamentals of blood formation in both invertebrate and vertebrates, examining the requirement of key signaling nexus in hematopoiesis. Knowledge obtained from such comparative studies associated with developmental dynamics of hematopoiesis is beneficial to explore the therapeutic options for hematopoietic diseases.

A Review of Placenta and Umbilical Cord-Derived Stem Cells and the Immunomodulatory Basis of Their Therapeutic Potential in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a devastating lung disorder of preterm infants as a result of an aberrant reparative response following exposures to various antenatal and postnatal insults. Despite sophisticated medical treatment in this modern era, the incidence of BPD remains unabated. The current strategies to prevent and treat BPD have met with limited success. The emergence of stem cell therapy may be a potential breakthrough in mitigating this complex chronic lung disorder. Over the last two decades, the human placenta and umbilical cord have gained increasing attention as a highly potential source of stem cells. Placenta-derived stem cells (PDSCs) and umbilical cord-derived stem cells (UCDSCs) display several advantages such as immune tolerance and are generally devoid of ethical constraints, in addition to their stemness qualities. They possess the characteristics of both embryonic and mesenchymal stromal/stem cells. Recently, there are many preclinical studies investigating the use of these cells as therapeutic agents in neonatal disease models for clinical applications. In this review, we describe the preclinical and clinical studies using PDSCs and UCDSCs as treatment in animal models of BPD. The source of these stem cells, routes of administration, and effects on immunomodulation, inflammation and regeneration in the injured lung are also discussed. Lastly, a brief description summarized the completed and ongoing clinical trials using PDSCs and UCDSCs as therapeutic agents in preventing or treating BPD. Due to the complexity of BPD, the development of a safe and efficient therapeutic agent remains a major challenge to both clinicians and researchers.

Impact of environmental neurotoxic: current methods and usefulness of human stem cells

The development of central nervous system is a highly coordinated and complex process. Any alteration of this process can lead to disturbances in the structure and function of the brain, which can cause deficits in neurological development, resulting in neurodevelopmental disorders, including, for example, autism or attention-deficit hyperactivity disorder. Exposure to certain chemicals during the fetal period and childhood is known to cause developmental neurotoxicity and has serious consequences that persist into adult life. For regulatory purposes, determination of the potential for developmental neurotoxicity is performed according the OECD Guideline 426, in which the test substance is administered to animals during gestation and lactation. However, these animal models are expensive, long-time consuming and may not reflect the physiology in humans; that makes it an unsustainable model to test the large amount of existing chemical products, hence alternative models to the use of animals are needed. One of the most promising methods is based on the use of stem cell technology. Stem cells are undifferentiated cells with the ability to self-renew and differentiate into more specialized cell types. Because of these properties, these cells have gained increased attention as possible therapeutic agents or as disease models. Here, we provide an overview of the current models both animal and cellular, available to study developmental neurotoxicity and review in more detail the usefulness of human stem cells, their properties and how they are becoming an alternative to evaluate and study the mechanisms of action of different environmental toxicants.

Human Pluripotent Stem Cells for Spinal Cord Injury

Spinal cord injury (SCI) as a serious public health issue and neurological insult is one of the most severe cause of long-term disability. To date, a variety of techniques have been widely developed to treat central nervous system injury. Currently, clinical treatments are limited to surgical decompression and pharmacotherapy. Because of their negative effects and inefficiency, novel therapeutic approaches are required in the management of SCI. Improvement and innovation of stem cell-based therapies have a huge potential for biological and future clinical applications. Human pluripotent stem cells (hPSCs) including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are defined by their abilities to divide asymmetrically, self-renew and ultimately differentiate into various cell lineages. There are considerable research efforts to use various types of stem cells, such as ESCs, neural stem cells (NSCs), and mesenchymal stem cells (MSCs) in the treatment of patients with SCI. Moreover, the use of patient-specific iPSCs holds great potential as an unlimited cell source for generating in vivo models of SCI. In this review, we focused on the potential of hPSCs in treating SCI.

Generation of brain organoids from mouse ESCs via teratoma formation

Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs), can differentiate into all cell types in the body; therefore, they are used in the study of development and regenerative medicine. Neural lineage differentiation from PSCs is the initial step to study neurodevelopment and in vitro disease modeling. Brain organoids, which are composed of neural stem cells (NSCs) and differentiated neural lineage cell population, are a powerful in vitro system to mimic the brain tissue. Here, we aimed to establish a new method to generate brain organoids efficiently in a mouse model. We applied the in vivo teratoma formation method as a new approach to generate brain organoids. We induced teratoma formation using Sox1-GFP transgenic ESCs, in which green fluorescence protein (GFP) is expressed under the control of the early NSC marker Sox1. Sox1-GFP-expressing early NSCs were isolated as clumps and further cultured to generate brain organoids. Sox1-GFP ESC-derived brain organoids, composed of multiple layers of distinct cellular components (ventricle, ventricular zone, and cortical layer), were formed within 3 weeks of in vitro culture. We also found that neighboring cells (Sox1-GFP^-) surrounding the Sox1-GFP⁺ clumps are essential for the formation of brain organoids. Thus, in vivo and in vitro conjugated systems-initial commitment in vivo and further specialization in vitro-could be one of the promising platforms for organoid formation that are universally applicable.

Roles of vitamins in stem cells

Stem cells can differentiate to diverse cell types in our body, and they hold great promises in both basic research and clinical therapies. For specific stem cell types, distinctive nutritional and signaling components are required to maintain the proliferation capacity and differentiation potential in cell culture. Various vitamins play essential roles in stem cell culture to modulate cell survival, proliferation and differentiation. Besides their common nutritional functions, specific vitamins are recently shown to modulate signal transduction and epigenetics. In this article, we will first review classical vitamin functions in both somatic and stem cell cultures. We will then focus on how stem cells could be modulated by vitamins beyond their nutritional roles. We believe that a better understanding of vitamin functions will significantly benefit stem cell research, and help realize their potentials in regenerative medicine.

Environmental exposures, stem cells, and cancer

An estimated 70-90% of all cancers are linked to exposure to environmental risk factors. In parallel, the number of stem cells in a tissue has been shown to be a strong predictor of risk of developing cancer in that tissue. Tumors themselves are characterized by an acquisition of "stem cell" characteristics, and a growing body of evidence points to tumors themselves being sustained and propagated by a stem cell-like population. Here, we review our understanding of the interplay between environmental exposures, stem cell biology, and cancer. We provide an overview of the role of stem cells in development, tissue homeostasis, and wound repair. We discuss the pathways and mechanisms governing stem cell plasticity and regulation of the stem cell state, and describe experimental methods for assessment of stem cells. We then review the current understanding of how environmental exposures impact stem cell function relevant to carcinogenesis and cancer prevention, with a focus on environmental and occupational exposures to chemical, physical, and biological hazards. We also highlight key areas for future research in this area, including defining whether the biological basis for cancer disparities is related to effects of complex exposure mixtures on stem cell biology.

Prenatal stem cell therapy for inherited diseases: Past, present, and future treatment strategies

Imagine the profits in quality of life that can be made by treating inherited diseases early in life, maybe even before birth! Immense cost savings can also be made by treating diseases promptly. Hence, prenatal stem cell therapy holds great promise for developing new and early‐stage treatment strategies for several diseases. Successful prenatal stem cell therapy would represent a major step forward in the management of patients with hematological, metabolic, or immunological disorders. However, treatment before birth has several limitations, including ethical issues. In this review, we summarize the past, the present, and the future of prenatal stem cell therapy, which includes an overview of different stem cell types, preclinical studies, and clinical attempts treating various diseases. We also discuss the current challenges and future strategies for prenatal stem cell therapy and also new approaches, which may lead to advancement in the management of patients with severe incurable diseases.

Mitochondrial plasticity in cell fate regulation

Mitochondria are considered highly plastic organelles. This plasticity enables the mitochondria to undergo morphological and functional changes in response to cellular demands. Stem cells also need to remain functionally plastic (i.e. to have the ability to "decide" whether to remain quiescent or to undergo activation upon signaling cues to support tissue function and homeostasis). Mitochondrial plasticity is thought to enable this reshaping of stem cell functions, integrating signaling cues with stem cell outcomes. Indeed, recent evidence highlights the crucial role of maintaining mitochondrial plasticity for stem cell biology. For example, tricarboxylic acid (TCA) cycle metabolites generated and metabolized in the mitochondria serve as cofactors for epigenetic enzymes, thereby coupling mitochondrial metabolism and transcriptional regulation. Another layer of mitochondrial plasticity has emerged, pointing toward mitochondrial dynamics in regulating stem cell fate decisions. Imposing imbalanced mitochondrial dynamics by manipulating the expression levels of the key molecular regulators of this process influences cellular outcomes by changing the nuclear transcriptional program. Moreover, reactive oxygen species have also been shown to play an important role in regulating transcriptional profiles in stem cells. In this review, we focus on recent findings demonstrating that mitochondria are essential regulators of stem cell activation and fate decisions. We also discuss the suggested mechanisms and alternative routes for mitochondria-to-nucleus communications.

Theranostics by testing CFTR modulators in patient-derived materials: The current status and a proposal for subjects with rare CFTR mutations

The last decade has witnessed developments in the CF drug pipeline which are both exciting and unprecedented, bringing with them previously unconsidered challenges. The Task Force group came together to consider these challenges and possible strategies to address them. Over the last 18 months, we have discussed internally and gathered views from a broad range of individuals representing patient organizations, clinical and research teams, the pharmaceutical industry and regulatory agencies. In this and the accompanying article, we discuss two main areas of focus: i) optimising trial design and delivery for speed/efficiency; ii) drug development for patients with rare CFTR mutations. We propose some strategies to tackle the challenges ahead and highlight areas where further thought is needed. We see this as the start of a process rather than the end and hope herewith to engage the wider community in seeking solutions to improved treatments for all patients with CF.