Clinical potentials of human pluripotent stem cells

Recent progress in the identification and in vitro culture of skin organoids

An organoid is a cell-based structure that shows organ-specific properties and shares a similar spatial organization as the corresponding organ. Organoids possess powerful capability to reproduce the key functions of the associated organ structures, and their similarity to the organs makes them physiologically relevant systems. The primary challenge associated with the development of skin organoids is the complexity of the human skin architecture, which encompasses the epidermis and the dermis as well as accessory structures, including hair follicles, sweat glands, and sebaceous glands, that perform various functions such as thermoregulation. The ultimate objectives of developing skin organoids are to regenerate the complete skin structure in vitro and reconstruct the skin in vivo. Consequently, safety, reliability, and the fidelity of the tissue interfaces are key considerations in this process. For this purpose, the present article reviews the most recent advances in this field, focusing on the cell sources, culture methods, culture conditions, and biomarkers for identifying the structure and function of skin organoids developed in vitro or in vivo. The subsequent sections summarize the recent applications of skin organoids in related disease diagnosis and treatments, and discuss the future prospects of these organoids in terms of clinical applications. This review of skin organoids can provide an important foundation for studies on human skin development, disease modeling, and reconstructive surgery, with broad utility for promising future opportunities in both biomedical research and clinical practice.

Bioengineering strategies for regeneration of skin integrity: A literature review

Objective

The skin is a complex organ that includes various stem cell populations. Current approaches for non-healing skin defects are sometimes inadequate and many attempts have been made to regenerate skin integrity. The aim of this review is to bridge the gap between basic research and clinical application of skin integrity regeneration.

Methods

A literature search was carried out in PubMed using combinations of the keywords "skin integrity", "tissue-engineered skin", "bioengineered skin", and "skin regeneration". Articles published from 1968 to 2023 reporting evidence from in vivo and in vitro skin regeneration experiments were included.

Results

These articles showed that stem cells can be differentiated into normal skin cells, including keratinocytes, and are a significant source of skin organoids, which are useful for investigating skin biology; and that emerging direct reprogramming methods have great potential to regenerate skin from the wounded skin surface.

Conclusion

Recent advances in skin regeneration will facilitate further advancement of both basic and clinical research in skin biology.

Stem cell therapy: A promising therapeutic approach for skeletal muscle atrophy

Skeletal muscle atrophy results from disruptions in the growth and metabolism of striated muscle, leading to a reduction or loss of muscle fibers. This condition not only significantly impacts patients’ quality of life but also imposes substantial socioeconomic burdens. The complex molecular mechanisms driving skeletal muscle atrophy contribute to the absence of effective treatment options. Recent advances in stem cell therapy have positioned it as a promising approach for addressing this condition. This article reviews the molecular mechanisms of muscle atrophy and outlines current therapeutic strategies, focusing on mesenchymal stem cells, induced pluripotent stem cells, and their derivatives. Additionally, the challenges these stem cells face in clinical applications are discussed. A deeper understanding of the regenerative potential of various stem cells could pave the way for breakthroughs in the prevention and treatment of muscle atrophy.

A Systematic Review and Meta-Analysis of Stem Cell Therapies for Pain in Diabetic Neuropathy, Osteoarthritis, and Spinal Cord Injuries

PURPOSE OF REVIEW

The use of stem cell therapy is a rapidly evolving and progressing frontier of science that has been used to treat illnesses such as malignancies, immunodeficiencies, and metabolic syndromes. This review aims to give an overview of the use of stem cell therapy in the treatment of pain caused by diabetic neuropathy, osteoarthritis, and other spinal cord pathologies.

RECENT FINDINGS

Pain is defined as a generalized or localized feeling of distress related to a physical or emotional stimulus and can be caused by a multitude of pathologies. The field of pain management has explored many strategies such as gene therapies, neuromodulation, platelet-rich plasma, and numerous pharmacotherapies. The approach to the delivery of these strategies has varied, with the method of stem cell therapy delivery being the focus of this present investigation. In addition, we combined several different studies to analyze the effects of stem cell therapies and improvement in pain scores quantified by the visual analog scale (VAS). The overall results showed a mean difference of -2.58, suggesting that the stem cell treatment group had a lower VAS score at 6 months compared to the control group. The use of different types of stem cells, such as pluripotent and mesenchymal stem cells, play a critical role in the care of cases suffering from pain. Effective delivery methods are evolving and can transform treatment options in the future, for which large cohort studies are warranted.

Artificial Gametes and Human Reproduction in the 21st Century: An Ethical Analysis

Artificial gametes, derived from stem cells, have the potential to enable in vitro fertilization of embryos. Currently, artificial gametes are only being generated in laboratory animals; however, considerable efforts are underway to develop artificial gametes using human cell sources. These artificial gametes are being proposed as a means to address infertility through assisted reproductive technologies. Nonetheless, the availability of artificial gametes obtained from adult organisms can potentially expand the possibilities of reproduction. Various groups, such as same-sex couples, post-menopausal women, and deceased donors, could potentially utilize artificial gametes to conceive genetically related offspring. The advent of artificial gametes raises significant bioethical questions. Should all these reproductive scenarios be accepted? How can we delineate the range of future reproductive choices? A normative bioethical framework may be necessary to establish a consensus regarding the use of human artificial gametes. This review aims to present the current state of research on the biological roadmap for generating artificial gametes, while also summarizing proposed approaches to establish a normative framework that delineates ethically acceptable paths for reproduction.

Generation of induced pluripotent stem cells from an individual with early onset and severe hypertrophic cardiomyopathy linked to MYBPC3: c.772G > A mutation

Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in the MYPBC3 gene, which encodes the cardiac myosin-binding protein C (cMyBP-C). Most pathogenic variants in MYPBC3 are either nonsense mutations or result in frameshifts, suggesting that the primary disease mechanism involves reduced functional cMyBP-C protein levels within sarcomeres. However, a subset of MYPBC3 variants are missense mutations, and the molecular mechanisms underlying their pathogenicity remain elusive. Upon in vitro differentiation into cardiomyocytes, induced pluripotent stem cells (iPSCs) derived from HCM patients represent a valuable resource for disease modeling. In this study, we generated two iPSC lines from peripheral blood mononuclear cells (PBMCs) of a female with early onset and severe HCM linked to the MYBPC3: c.772G > A variant. Although this variant was initially classified as a missense mutation, recent studies indicate that it interferes with splicing and results in a frameshift. The generated iPSC lines exhibit a normal karyotype and display hallmark characteristics of pluripotency, including the ability to undergo trilineage differentiation. These novel iPSCs expand the existing repertoire of MYPBC3-mutated cell lines, broadening the spectrum of resources for exploring how diverse mutations induce HCM. They additionally offer a platform to study potential secondary genetic elements contributing to the pronounced disease severity observed in this individual.

Evaluating the pro-survival potential of apoptotic bodies derived from 2D- and 3D- cultured adipose stem cells in ischaemic flaps

In the realm of large-area trauma flap transplantation, averting ischaemic necrosis emerges as a pivotal concern. Several key mechanisms, including the promotion of angiogenesis, the inhibition of oxidative stress, the suppression of cell death, and the mitigation of inflammation, are crucial for enhancing skin flap survival. Apoptotic bodies (ABs), arising from cell apoptosis, have recently emerged as significant contributors to these functions. This study engineered three-dimensional (3D)-ABs using tissue-like mouse adipose-derived stem cells (mADSCs) cultured in a 3D environment to compare their superior biological effects against 2D-ABs in bolstering skin flap survival. The findings reveal that 3D-ABs (85.74 ± 4.51) % outperform 2D-ABs (76.48 ± 5.04) % in enhancing the survival rate of ischaemic skin flaps (60.45 ± 8.95) % (all p < 0.05). Mechanistically, they stimulated angiogenesis, mitigated oxidative stress, suppressed apoptosis, and facilitated the transition of macrophages from M1 to M2 polarization (all p < 0.05). A comparative analysis of microRNA (miRNA) profiles in 3D- and 2D-ABs identified several specific miRNAs (miR-423-5p-up, miR30b-5p-down, etc.) with pertinent roles. In summary, ABs derived from mADSCs cultured in a 3D spheroid-like arrangement exhibit heightened biological activity compared to those from 2D-cultured mADSCs and are more effective in promoting ischaemic skin flap survival. These effects are attributed to their influence on specific miRNAs.

Comparative transcriptomic and phenotypic analysis of induced pluripotent stem cell hepatocyte-like cells and primary human hepatocytes

Primary human hepatocytes (PHHs) are used extensively for in vitro liver cultures to study hepatic functions. However, limited availability and invasive retrieval prevent their widespread use. Induced pluripotent stem cells exhibit significant potential since they can be obtained non-invasively and differentiated into hepatic lineages, such as hepatocyte-like cells (iHLCs). However, there are concerns about their fetal phenotypic characteristics and their hepatic functions compared to PHHs in culture. Therefore, we performed an RNA-sequencing (RNA-seq) analysis to understand pathways that are either up- or downregulated in each cell type. Analysis of the RNA-seq data showed an upregulation in the bile secretion pathway where genes such as AQP9 and UGT1A1 were higher expressed in PHHs compared to iHLCs by 455- and 15-fold, respectively. Upon immunostaining, bile canaliculi were shown to be present in PHHs. The TCA cycle in PHHs was upregulated compared to iHLCs. Cellular analysis showed a 2-2.5-fold increase in normalized urea production in PHHs compared to iHLCs. In addition, drug metabolism pathways, including cytochrome P450 (CYP450) and UDP-glucuronosyltransferase enzymes, were upregulated in PHHs compared to iHLCs. Of note, CYP2E1 gene expression was significantly higher (21,810-fold) in PHHs. Acetaminophen and ethanol were administered to PHH and iHLC cultures to investigate differences in biotransformation. CYP450 activity of baseline and toxicant-treated samples was significantly higher in PHHs compared to iHLCs. Our analysis revealed that iHLCs have substantial differences from PHHs in critical hepatic functions. These results have highlighted the differences in gene expression and hepatic functions between PHHs and iHLCs to motivate future investigation.

The Material World of 3D-Bioprinted and Microfluidic-Chip Models of Human Liver Fibrosis

Biomaterials are extensively used to mimic cell-matrix interactions, which are essential for cell growth, function, and differentiation. This is particularly relevant when developing in vitro disease models of organs rich in extracellular matrix, like the liver. Liver disease involves a chronic wound-healing response with formation of scar tissue known as fibrosis. At early stages, liver disease can be reverted, but as disease progresses, reversion is no longer possible, and there is no cure. Research for new therapies is hampered by the lack of adequate models that replicate the mechanical properties and biochemical stimuli present in the fibrotic liver. Fibrosis is associated with changes in the composition of the extracellular matrix that directly influence cell behavior. Biomaterials could play an essential role in better emulating the disease microenvironment. In this paper, the recent and cutting-edge biomaterials used for creating in vitro models of human liver fibrosis are revised, in combination with cells, bioprinting, and/or microfluidics. These technologies have been instrumental to replicate the intricate structure of the unhealthy tissue and promote medium perfusion that improves cell growth and function, respectively. A comprehensive analysis of the impact of material hints and cell-material interactions in a tridimensional context is provided.

The role of c-Jun for beating cardiomycyte formation in prepared embryonic body

BACKGROUND

Morbidity and mortality associated with cardiovascular diseases, such as myocardial infarction, stem from the inability of terminally differentiated cardiomyocytes to regenerate, and thus repair the damaged myocardial tissue structure. The molecular biological mechanisms behind the lack of regenerative capacity for those cardiomyocytes remains to be fully elucidated. Recent studies have shown that c-Jun serves as a cell cycle regulator for somatic cell fates, playing a key role in multiple molecular pathways, including the inhibition of cellular reprogramming, promoting angiogenesis, and aggravation of cardiac hypertrophy, but its role in cardiac development is largely unknown. This study aims to delineate the role of c-Jun in promoting early-stage cardiac differentiation.

METHODS

The c-Jun gene in mouse embryonic stem cells (mESCs) was knocked out with CRISPR-Cas9, and the hanging drop method used to prepare the resulting embryoid bodies. Cardiac differentiation was evaluated up to 9 days after c-Jun knockout (ko) via immunofluorescence, flow cytometric, and qPCR analyses.

RESULTS

Compared to the wild-type control group, obvious beating was observed among the c-Jun-ko mESCs after 6 days, which was also associated with significant increases in myocardial marker expression. Additionally, markers associated with mesoderm and endoderm cell layer development, essential for further differentiation of ESCs into cardiomyocytes, were also up-regulated in the c-Jun-ko cell group.

CONCLUSIONS

Knocking out c-Jun directs ESCs toward a meso-endodermal cell lineage fate, in turn leading to generation of beating myocardial cells. Thus, c-Jun plays an important role in regulating early cardiac cell development.

Stem cell therapy for hepatocellular carcinoma and end-stage liver disease

Hepatocellular carcinoma (HCC) is a major health problem worldwide, especially for patients who are suffering from end-stage liver disease (ESLD). The ESLD is considered a great challenge for clinicians due to the limited chance for liver transplantation, which is the only curative treatment for those patients. Stem cell-based therapy as a part of regenerative medicine represents a promising application for ESLD patients. Many clinical trials were performed to assess the utility of bone marrow-derived stem cells as a potential therapy for patients with liver diseases. The aim of the present study is to present and review the various types of stem cell-based therapy, including the mesenchymal stem cells (MSCs), BM-derived mononuclear cells (BM-MNCs), CD34 + hematopoietic stem cells (HSCs), induced pluripotent stem cells (iPSCs), and cancer stem cells.Though this type of therapy achieved promising results for the treatment of ESLD, however still there is a confounding data regarding its clinical application. A large body of evidence is highly required to evaluate the stem cell-based therapy after long-term follow-up, with respect to the incidence of toxicity, immunogenicity, and tumorigenesis that developed in many patients.

Generation of an induced pluripotent stem cell line from a patient with epileptic encephalopathy caused by the CYFIP2 R87C variant

Induced pluripotent stem cells (iPSCs) opened the possibility to use patient cells as a model for several diseases. iPSCs can be reprogrammed from somatic cells collected in a non-invasive way, and then differentiated into any other cell type, while maintaining the donor´s genetic background. CYFIP2 variants were associated with the onset of an early form of epileptic encephalopathy. Studies with patients showed that the R87C variant seems to be one of the variants that causes more severe disease, however, to date there are no studies with a human cell model that allows investigation of the neuronal phenotype of the R87C variant. Here, we generated an iPSC line from a patient with epileptic encephalopathy caused by the CYFIP2 R87C variant. We obtained iPSC clones by reprogramming urinary progenitor cells from a female patient. The generated iPSC line presented a pluripotent stem cell morphology, normal karyotype, expressed pluripotency markers and could be differentiated into the three germ layers. In further studies, this cell line could be used as model for epileptic encephalopathy disease and drug screening studies.

The pseudoenzyme ADPRHL1 affects cardiac function by regulating the ROCK pathway

BACKGROUND

Pseudoenzymes, catalytically deficient variants of active enzymes, have a wide range of regulatory functions. ADP-ribosylhydrolase-like 1 (ADPRHL1), a pseudoenzyme belonging to a small group of ADP-ribosylhydrolase enzymes that lacks the amino acid residues necessary for catalytic activity, may have a significant role in heart development based on accumulating evidence. However, the specific function of ADPRHL1 in this process has not been elucidated. To investigate the role of ADPRHL1 in the heart, we generated the first in vitro human embryonic stem cell model with an ADPRHL1 knockout.

METHOD

Using the CRISPR/Cas9 system, we generated ADPRHL1 knockout in the human embryonic stem cell (hESC) H9 line. The cells were differentiated into cardiomyocytes using a chemically defined and xeno-free method. We employed confocal laser microscopy to detect calcium transients and microelectrode array (MEA) to assess the electrophysiological activity of ADPRHL1 deficiency cardiomyocytes. Additionally, we investigated the cellular mechanism of ADPRHL1 by Bulk RNA sequencing and western blot.

RESULTS

The results indicate that the absence of ADPRHL1 in cardiomyocytes led to adhered abnormally, as well as perturbations in calcium transients and electrophysiological activity. We also revealed that disruption of focal adhesion formation in these cardiomyocytes was due to an excessive upregulation of the ROCK-myosin II pathway. Notably, inhibition of ROCK and myosin II effectively restores focal adhesions in ADPRHL1-deficient cardiomyocytes and improved electrical conduction and calcium activity.

CONCLUSIONS

Our findings demonstrate that ADPRHL1 plays a critical role in maintaining the proper function of cardiomyocytes by regulating the ROCK-myosin II pathway, suggesting that it may serve as a potential drug target for the treatment of ADPRHL1-related diseases.

APE1 promotes embryonic stem cell proliferation and teratoma formation by regulating GDNF/GFRα1 axis

The teratomas formation has severely hindered the application of embryonic stem cells (ESCs) in clinical trials. Apurinic/apyrimidinic endonuclease 1 (APE1) is strongly involved in the development of tumors and differentiation process of stem cells. However, the role of APE1 in teratomas remains unknown. The expression of APE1 was examined in mouse ESCs (mESCs) by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot. The role and mechanism of APE1 in the proliferation, pluripotency and differentiation of E14 cells were determined by cell counting, flow cytometry and western blot assays. Besides, the role of APE1 in teratomas was also probed in xenografted mice. The expression of APE1 was upregulated in mESCs with differentiation. Knockdown of APE1 reduced the cell numbers, induced the arrest of the G2/M phase, and decreased the expression of cell cycle-related proteins in E14 cells. Besides, loss- and gain-of-function assays revealed that APE1 enhanced the levels of proteins involved in pluripotency, reduced the protein expression of ectoderm markers, and increased the protein levels of endoderm markers in E14 cells. Mechanically, inhibition of APE1 downregulated the expression of GDNF and GFRα1 in E14 cells. GDNF reversed the role of APE1 in the proliferation, pluripotency and embryogenesis of E14 cells. Moreover, suppression of APE1 reduced the teratoma volume and the relative protein expression of endoderm markers, but increased the relative protein expression of ectoderm markers in xenografted mice. Collectively, knockdown of APE1 attenuated proliferation, pluripotency and embryogenesis of mESCs via GDNF/GFRα1 axis.

Human iPSC-Derived 3D Hepatic Organoids in a Miniaturized Dynamic Culture System

The process of identifying and approving a new drug is a time-consuming and expensive procedure. One of the biggest issues to overcome is the risk of hepatotoxicity, which is one of the main reasons for drug withdrawal from the market. While animal models are the gold standard in preclinical drug testing, the translation of results into therapeutic intervention is often ambiguous due to interspecies differences in hepatic metabolism. The discovery of human induced pluripotent stem cells (hiPSCs) and their derivatives has opened new possibilities for drug testing. We used mesenchymal stem cells and hepatocytes both derived from hiPSCs, together with endothelial cells, to miniaturize the process of generating hepatic organoids. These organoids were then cultivated in vitro using both static and dynamic cultures. Additionally, we tested spheroids solely composed by induced hepatocytes. By miniaturizing the system, we demonstrated the possibility of maintaining the organoids, but not the spheroids, in culture for up to 1 week. This timeframe may be sufficient to carry out a hypothetical pharmacological test or screening. In conclusion, we propose that the hiPSC-derived liver organoid model could complement or, in the near future, replace the pharmacological and toxicological tests conducted on animals.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

Cellular rejuvenation: molecular mechanisms and potential therapeutic interventions for diseases

The ageing process is a systemic decline from cellular dysfunction to organ degeneration, with more predisposition to deteriorated disorders. Rejuvenation refers to giving aged cells or organisms more youthful characteristics through various techniques, such as cellular reprogramming and epigenetic regulation. The great leaps in cellular rejuvenation prove that ageing is not a one-way street, and many rejuvenative interventions have emerged to delay and even reverse the ageing process. Defining the mechanism by which roadblocks and signaling inputs influence complex ageing programs is essential for understanding and developing rejuvenative strategies. Here, we discuss the intrinsic and extrinsic factors that counteract cell rejuvenation, and the targeted cells and core mechanisms involved in this process. Then, we critically summarize the latest advances in state-of-art strategies of cellular rejuvenation. Various rejuvenation methods also provide insights for treating specific ageing-related diseases, including cellular reprogramming, the removal of senescence cells (SCs) and suppression of senescence-associated secretory phenotype (SASP), metabolic manipulation, stem cells-associated therapy, dietary restriction, immune rejuvenation and heterochronic transplantation, etc. The potential applications of rejuvenation therapy also extend to cancer treatment. Finally, we analyze in detail the therapeutic opportunities and challenges of rejuvenation technology. Deciphering rejuvenation interventions will provide further insights into anti-ageing and ageing-related disease treatment in clinical settings.

Plausible Role of Stem Cell Types for Treating and Understanding the Pathophysiology of Depression

Major Depressive Disorder (MDD), colloquially known as depression, is a debilitating condition affecting an estimated 3.8% of the population globally, of which 5.0% are adults and 5.7% are above the age of 60. MDD is differentiated from common mood changes and short-lived emotional responses due to subtle alterations in gray and white matter, including the frontal lobe, hippocampus, temporal lobe, thalamus, striatum, and amygdala. It can be detrimental to a person’s overall health if it occurs with moderate or severe intensity. It can render a person suffering terribly to perform inadequately in their personal, professional, and social lives. Depression, at its peak, can lead to suicidal thoughts and ideation. Antidepressants manage clinical depression and function by modulating the serotonin, norepinephrine, and dopamine neurotransmitter levels in the brain. Patients with MDD positively respond to antidepressants, but 10–30% do not recuperate or have a partial response accompanied by poor life quality, suicidal ideation, self-injurious behavior, and an increased relapse rate. Recent research shows that mesenchymal stem cells and iPSCs may be responsible for lowering depression by producing more neurons with increased cortical connections. This narrative review discusses the plausible functions of various stem cell types in treating and understanding depression pathophysiology.

Modeling of Respiratory Diseases Evolving with Fibrosis from Organoids Derived from Human Pluripotent Stem Cells

Respiratory disease is one of the leading causes of morbidity and mortality worldwide. There is no cure for most diseases, which are treated symptomatically. Hence, new strategies are required to deepen the understanding of the disease and development of therapeutic strategies. The advent of stem cell and organoid technology has enabled the development of human pluripotent stem cell lines and adequate differentiation protocols for developing both airways and lung organoids in different formats. These novel human-pluripotent-stem-cell-derived organoids have enabled relatively accurate disease modeling. Idiopathic pulmonary fibrosis is a fatal and debilitating disease that exhibits prototypical fibrotic features that may be, to some extent, extrapolated to other conditions. Thus, respiratory diseases such as cystic fibrosis, chronic obstructive pulmonary disease, or the one caused by SARS-CoV-2 may reflect some fibrotic aspects reminiscent of those present in idiopathic pulmonary fibrosis. Modeling of fibrosis of the airways and the lung is a real challenge due to the large number of epithelial cells involved and interaction with other cell types of mesenchymal origin. This review will focus on the status of respiratory disease modeling from human-pluripotent-stem-cell-derived organoids, which are being used to model several representative respiratory diseases, such as idiopathic pulmonary fibrosis, cystic fibrosis, chronic obstructive pulmonary disease, and COVID-19.

Pharmacological and Nutraceutical Activation of Rejuvenation, Geroprotection and Cytoprotection: Proofs of Concept

Aging is a process associated with life [...].

The impact of low intensity ultrasound on cells: Underlying mechanisms and current status

Low intensity ultrasound (LIUS) has been adopted for a variety of therapeutic purposes because of its bioeffects such as thermal, mechanical, and cavitation effects. The mechanism of impact and cellular responses of LIUS in cellular regulations have been revealed, which helps to understand the role of LIUS in tumor treatment, stem cell therapy, and nervous system regulation. The review summarizes the bioeffects of LIUS at the cellular level and its related mechanisms, detailing the corresponding theoretical basis and latest research in the study of LIUS in the regulation of cells. In the future, the design of specific LIUS-mediated treatment strategies may benefit from promising investigations which is hoped to provide encouraging therapeutic data.

1H NMR Metabolite Monitoring during the Differentiation of Human Induced Pluripotent Stem Cells Provides New Insights into the Molecular Events That Regulate Embryonic Chondrogenesis

The integration of cell metabolism with signalling pathways, transcription factor networks and epigenetic mediators is critical in coordinating molecular and cellular events during embryogenesis. Induced pluripotent stem cells (IPSCs) are an established model for embryogenesis, germ layer specification and cell lineage differentiation, advancing the study of human embryonic development and the translation of innovations in drug discovery, disease modelling and cell-based therapies. The metabolic regulation of IPSC pluripotency is mediated by balancing glycolysis and oxidative phosphorylation, but there is a paucity of data regarding the influence of individual metabolite changes during cell lineage differentiation. We used ¹H NMR metabolite fingerprinting and footprinting to monitor metabolite levels as IPSCs are directed in a three-stage protocol through primitive streak/mesendoderm, mesoderm and chondrogenic populations. Metabolite changes were associated with central metabolism, with aerobic glycolysis predominant in IPSC, elevated oxidative phosphorylation during differentiation and fatty acid oxidation and ketone body use in chondrogenic cells. Metabolites were also implicated in the epigenetic regulation of pluripotency, cell signalling and biosynthetic pathways. Our results show that ¹H NMR metabolomics is an effective tool for monitoring metabolite changes during the differentiation of pluripotent cells with implications on optimising media and environmental parameters for the study of embryogenesis and translational applications.

Induced Pluripotent Stem Cell-Derived Corneal Cells: Current Status and Application

Deficiency and dysfunction of corneal cells leads to the blindness observed in corneal diseases such as limbal stem cell deficiency (LSCD) and bullous keratopathy. Regenerative cell therapies and engineered corneal tissue are promising treatments for these diseases [1]. However, these treatments are not yet clinically feasible due to inadequate cell sources. The discovery of induced pluripotent stem cells (iPSCs) by Shinya Yamanaka has provided a multitude of opportunities in research because iPSCs can be generated from somatic cells, thus providing an autologous and unlimited source for corneal cells. Compared to other stem cell sources such as mesenchymal and embryonic, iPSCs have advantages in differentiation potential and ethical concerns, respectively. Efforts have been made to use iPSCs to model corneal disorders and diseases, drug testing [2], and regenerative medicine [1]. Autologous treatments based on iPSCs can be exorbitantly expensive and time-consuming, but development of stem cell banks with human leukocyte antigen (HLA)- homozygous cell lines can provide cost- and time-efficient allogeneic alternatives. In this review, we discuss the early development of the cornea because protocols differentiating iPSCs toward corneal lineages rely heavily upon recapitulating this development. Differentiation of iPSCs toward corneal cell phenotypes have been analyzed with an emphasis on feeder-free, xeno-free, and well-defined protocols, which have clinical relevance. The application, challenges, and potential of iPSCs in corneal research are also discussed with a focus on hurdles that prevent clinical translation.

Cancer Risk and Mutational Patterns Following Organ Transplantation

The rapid development of medical technology and widespread application of immunosuppressive drugs have improved the success rate of organ transplantation significantly. However, the use of immunosuppressive agents increases the frequency of malignancy greatly. With the prospect of “precision medicine” for tumors and development of next-generation sequencing technology, more attention has been paid to the application of high-throughput sequencing technology in clinical oncology research, which is mainly applied to the early diagnosis of tumors and analysis of tumor-related genes. All generations of cancers carry somatic mutations, meanwhile, significant differences were observed in mutational signatures across tumors. Systematic sequencing of cancer genomes from patients after organ transplantation can reveal DNA damage and repair processes in exposed cancer cells and their precursors. In this review, we summarize the application of high-throughput sequencing and organoids in the field of organ transplantation, the mutational patterns of cancer genomes, and propose a new research strategy for understanding the mechanism of cancer following organ transplantation.

Investigating Cutaneous Squamous Cell Carcinoma in vitro and in vivo: Novel 3D Tools and Animal Models

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin reconstructs and organoids. Although 3D models demonstrate high potential to enhance the overall knowledge in cancer research, they lack systemic components which may be solved only by using animal models. Zebrafish is emerging as an alternative xenotransplant model in cancer research, offering a high-throughput approach for drug screening and real-time in vivo imaging to study cell invasion. Moreover, several categories of mouse models were developed for pre-clinical purpose, including xeno- and syngeneic transplantation models, autochthonous models of chemically or UV-induced skin squamous carcinogenesis, and genetically engineered mouse models (GEMMs) of cSCC. These models have been instrumental in examining the molecular mechanisms of cSCC and drug response in an in vivo setting. The present review proposes an overview of in vitro, particularly 3D, and in vivo models and their application in cutaneous SCC research.

Cocktail Formula and Application Prospects for Oral and Maxillofacial Organoids

Oral and maxillofacial organoids (OMOs), tiny tissues and organs derived from stem cells cultured through 3-d cell culture models, can fully summarize the cell tissue structure, physiological functions and biological characteristics of the source tissues in the body. OMOs are applied in areas such as disease modelling, developmental and regenerative medicine, drug screening, personalized treatment, etc. Although the construction of organoids in various parts of the oral and maxillofacial (OM) region has achieved considerable success, the existing cocktail formulae (construction strategies) are not widely applicable for tissues of various sources due to factors including the heterogeneity of the source tissues and the dependence on laboratory technology. Most of their formulae are based on growth factor niches containing expensive recombinant proteins with their efficiency remaining to be improved. In view of this, the cocktail formulae of various parts of the OM organs are reviewed with further discussion of the application and prospects for those OMOs to find some affordable cocktail formula with strong operability and high repeatability for various maxillofacial organs. The results may help improve the efficiency of organoid construction in the laboratory and accelerate the pace of the clinical use of organoid technology.

Schwann Cells Promote Myogenic Differentiation of Myoblasts and Adipogenic Mesenchymal Stromal Cells on Poly-ɛ-Caprolactone-Collagen I-Nanofibers

For the purpose of skeletal muscle tissue engineering, different cell types have been investigated regarding their myogenic differentiation potential, including co-cultured myoblasts and adipogenic mesenchymal stromal cells (Mb/ADSC). As neural cells enhance synaptic junction formation, the aim of this study was to co-culture Schwann cells (SCs) with Mb/ADSC on biocompatible electrospun aligned poly-ε-polycaprolacton (PCL)-collagen I-nanofibers. It was hypothesized that SCs, as part of the peripheral nervous system, promote the myogenic differentiation of Mb/ADSC co-cultures. Mb/ADSC were compared to Mb/ADSC/SC regarding their capacity for myogenic differentiation via immunofluorescent staining and gene expression of myogenic markers. Mb/ADSC/SC showed more myotubes after 28 days of differentiation (p ≤ 0.05). After 28 days of differentiation on electrospun aligned PCL-collagen I-nanofibers, gene expression of myosin heavy chains (MYH2) and myogenin (MYOG) was upregulated in Mb/ADSC/SC compared to Mb/ADSC (p ≤ 0.01 and p ≤ 0.05, respectively). Immunofluorescent staining for MHC showed highly aligned multinucleated cells as possible myotube formation in Mb/ADSC/SC. In conclusion, SCs promote myogenic differentiation of Mb/ADSC. The co-culture of primary Mb/ADSC/SC on PCL-collagen I-nanofibers serves as a physiological model for skeletal muscle tissue engineering, applicable to future clinical applications.

Human iPSC-Derived Renal Cells Change Their Immunogenic Properties during Maturation: Implications for Regenerative Therapies

The success of human induced pluripotent stem cell (hiPSC)-based therapy critically depends on understanding and controlling the immunological effects of the hiPSC-derived transplant. While hiPSC-derived cells used for cell therapy are often immature with post-grafting maturation, immunological properties may change, with adverse effects on graft tolerance and control. In the present study, the allogeneic and autologous cellular immunity of hiPSC-derived progenitor and terminally differentiated cells were investigated in vitro. In contrast to allogeneic primary cells, hiPSC-derived early renal progenitors and mature renal epithelial cells are both tolerated not only by autologous but also by allogeneic T cells. These immune-privileged properties result from active immunomodulation and low immune visibility, which decrease during the process of cell maturation. However, autologous and allogeneic natural killer (NK) cell responses are not suppressed by hiPSC-derived renal cells and effectively change NK cell activation status. These findings clearly show a dynamic stage-specific dependency of autologous and allogeneic T and NK cell responses, with consequences for effective cell therapies. The study suggests that hiPSC-derived early progenitors may provide advantageous immune-suppressive properties when applied in cell therapy. The data furthermore indicate a need to suppress NK cell activation in allogeneic as well as autologous settings.

Anti-fibrotic effect of adipose-derived stem cells on fibrotic scars

BACKGROUND

Sustained injury, through radiotherapy, burns or surgical trauma, can result in fibrosis, displaying an excessive deposition of extracellular matrix (ECM), persisting inflammatory reaction, and reduced vascularization. The increasing recognition of fibrosis as a cause for disease and mortality, and increasing use of radiotherapy causing fibrosis, stresses the importance of a decent anti-fibrotic treatment.

AIM

To obtain an in-depth understanding of the complex mechanisms underlying fibrosis, and more specifically, the potential mechanisms-of-action of adipose-derived stomal cells (ADSCs) in realizing their anti-fibrotic effect.

METHODS

A systematic review of the literature using PubMed, Embase and Web of Science was performed by two independent reviewers.

RESULTS

The injection of fat grafts into fibrotic tissue, releases ADSC into the environment. ADSCs’ capacity to directly differentiate into key cell types (e.g., ECs, fibroblasts), as well as to secrete multiple paracrine factors (e.g., hepatocyte growth factor, basis fibroblast growth factor, IL-10), allows them to alter different mechanisms underlying fibrosis in a combined approach. ADSCs favor ECM degradation by impacting the fibroblast-to-myofibroblast differentiation, favoring matrix metalloproteinases over tissue inhibitors of metalloproteinases, positively influencing collagen organization, and inhibiting the pro-fibrotic effects of transforming growth factor-β1. Furthermore, they impact elements of both the innate and adaptive immune response system, and stimulate angiogenesis on the site of injury (through secretion of pro-angiogenic cytokines like stromal cell-derived factor-1 and vascular endothelial growth factor).

CONCLUSION

This review shows that understanding the complex interactions of ECM accumulation, immune response and vascularization, is vital to fibrosis treatments’ effectiveness like fat grafting. It details how ADSCs intelligently steer this complex system in an anti-fibrotic or pro-angiogenic direction, without falling into extreme dilation or stimulation of a single aspect. Detailing this combined approach, has brought fat grafting one step closer to unlocking its full potential as a non-anecdotal treatment for fibrosis.

The Role of Endoplasmic Reticulum and Mitochondria in Maintaining Redox Status and Glycolytic Metabolism in Pluripotent Stem Cells

Pluripotent stem cells (PSCs), including embryonic stem cells and induced pluripotent stem cells (iPSCs), can be applicable for regenerative medicine. They strangely rely on glycolysis metabolism akin to aerobic glycolysis in cancer cells. Upon differentiation, PSCs undergo a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS). The metabolic shift depends on organelles maturation, transcriptome modification, and metabolic switching. Besides, metabolism-driven chromatin regulation is necessary for cell survival, self-renewal, proliferation, senescence, and differentiation. In this respect, mitochondria may serve as key organelle to adapt environmental changes with metabolic intermediates which are necessary for maintaining PSCs identity. The endoplasmic reticulum (ER) is another organelle whose role in cellular identity remains under-explored. The purpose of our article is to highlight the recent progress on these two organelles' role in maintaining PSCs redox status focusing on metabolism. Topics include redox status, metabolism regulation, mitochondrial dynamics, and ER stress in PSCs. They relate to the maintenance of stem cell properties and subsequent differentiation of stem cells into specific cell types.

Generation of Skin Organoids: Potential Opportunities and Challenges

Although several types of human skin substitutes are currently available, they usually do not include important skin appendages such as hair follicles and sweat glands, or various skin-related cells, such as dermal adipocytes and sensory neurons. This highlights the need to improve the in vitro human skin generation model for use as a tool for investigating skin diseases and as a source of cells or tissues for skin regeneration. Skin organoids are generated from stem cells and are expected to possess the complexity and function of natural skin. Here, we summarize the current literatures relating to the "niches" of the local skin stem cell microenvironment and the formation of skin organoids, and then discuss the opportunities and challenges associated with multifunctional skin organoids.

Critical Analysis of cGMP Large-Scale Expansion Process in Bioreactors of Human Induced Pluripotent Stem Cells in the Framework of Quality by Design

Human induced pluripotent stem cells (hiPSCs) are manufactured as advanced therapy medicinal products for tissue replacement applications. With this aim, the feasibility of hiPSC large-scale expansion in existing bioreactor systems under current good manufacturing practices (cGMP) has been tested. Yet, these attempts have lacked a paradigm shift in culture settings and technologies tailored to hiPSCs, which jeopardizes their clinical translation. The best approach for industrial scale-up of high-quality hiPSCs is to design their manufacturing process by following quality-by-design (QbD) principles: a scientific, risk-based framework for process design based on relating product and process attributes to product quality. In this review, we analyzed the hiPSC expansion manufacturing process implementing the QbD approach in the use of bioreactors, stressing the decisive role played by the cell quantity, quality and costs, drawing key QbD concepts directly from the guidelines of the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use.

WITHDRAWN: Knocking out c-Jun promotes cardiomyocyte differentiation from embryonic stem cells

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Selection of different endothelialization modes and different seed cells for tissue-engineered vascular graft

Tissue-engineered vascular grafts (TEVGs) have enormous potential for vascular replacement therapy. However, thrombosis and intimal hyperplasia are important problems associated with TEVGs especially small diameter TEVGs (<6 mm) after transplantation. Endothelialization of TEVGs is a key point to prevent thrombosis. Here, we discuss different types of endothelialization and different seed cells of tissue-engineered vascular grafts. Meanwhile, endothelial heterogeneity is also discussed. Based on it, we provide a new perspective for selecting suitable types of endothelialization and suitable seed cells to improve the long-term patency rate of tissue-engineered vascular grafts with different diameters and lengths.

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The material, diameter and length of tissue-engineered vascular graft are all key factors affecting its long-term patency.

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Endothelialization strategies should consider the different diameters and lengths of tissue-engineered vascular grafts.

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Cell heterogeneity and tissue heterogeneity should be considered in the application of seed cells.

Transcriptomic Analysis of Naïve Human Embryonic Stem Cells Cultured in Three-Dimensional PEG Scaffolds

Naïve human embryonic stem cells (ESCs) are characterized by improved viability, proliferation, and differentiation capacity in comparison to traditionally derived primed human ESCs. However, currently used two-dimensional (2-D) cell culture techniques fail to mimic the three-dimensional (3-D) in vivo microenvironment, altering morphological and molecular characteristics of ESCs. Here, we describe the use of 3-D self-assembling scaffolds that support growth and maintenance of the naïve state characteristics of ESC line, Elf1. Scaffolds were formed via a Michael addition reaction upon the combination of two 8-arm polyethylene glycol (PEG) polymers functionalized with thiol (PEG-8-SH) and acrylate (PEG-8-Acr) end groups. 3-D scaffold environment maintained the naïve state and supported the long-term growth of ESCs. RNA-sequencing demonstrated significant changes in gene expression profiles between 2-D and 3-D grown cells. Gene ontology analysis revealed upregulation of biological processes involved in the regulation of transcription and translation, extracellular matrix organization, and chromatin remodeling in 3-D grown cells. 3-D culture conditions also induced upregulation of genes associated with Wnt and focal adhesion signaling, while p53 signaling pathway associated genes were downregulated. Our findings, for the first time, provide insight into the possible mechanisms of self-renewal of naïve ESCs stimulated by the transduction of mechanical signals from the 3-D microenvironment.

Retrotransposons in pluripotent stem cells

Transposable elements constitute about half of the mammalian genome, and can be divided into two classes: the class I (retrotransposons) and the class II (DNA transposons). A few hundred types of retrotransposons, which are dynamic and stage specific, have been annotated. The copy numbers and genomic locations are significantly varied in species. Retrotransposons are active in germ cells, early embryos and pluripotent stem cells (PSCs) correlated with low levels of DNA methylation in epigenetic regulation. Some key pluripotency transcriptional factors (such as OCT4, SOX2, and NANOG) bind retrotransposons and regulate their activities in PSCs, suggesting a vital role of retrotransposons in pluripotency maintenance and self-renewal. In response to retrotransposons transposition, cells employ a number of silencing mechanisms, such as DNA methylation and histone modification. This review summarizes expression patterns, functions, and regulation of retrotransposons in PSCs and early embryonic development.

Improved Computational Identification of Drug Response Using Optical Measurements of Human Stem Cell Derived Cardiomyocytes in Microphysiological Systems

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) hold great potential for drug screening applications. However, their usefulness is limited by the relative immaturity of the cells' electrophysiological properties as compared to native cardiomyocytes in the adult human heart. In this work, we extend and improve on methodology to address this limitation, building on previously introduced computational procedures which predict drug effects for adult cells based on changes in optical measurements of action potentials and Ca2+ transients made in stem cell derived cardiac microtissues. This methodology quantifies ion channel changes through the inversion of data into a mathematical model, and maps this response to an adult phenotype through the assumption of functional invariance of fundamental intracellular and membrane channels during maturation. Here, we utilize an updated action potential model to represent both hiPSC-CMs and adult cardiomyocytes, apply an IC50-based model of dose-dependent drug effects, and introduce a continuation-based optimization algorithm for analysis of dose escalation measurements using five drugs with known effects. The improved methodology can identify drug induced changes more efficiently, and quantitate important metrics such as IC50 in line with published values. Consequently, the updated methodology is a step towards employing computational procedures to elucidate drug effects in adult cardiomyocytes for new drugs using stem cell-derived experimental tissues.

Corneal cell therapy: with iPSCs, it is no more a far-sight

Human-induced pluripotent stem cells (hiPSCs) provide a personalized approach to study conditions and diseases including those of the eye that lack appropriate animal models to facilitate the development of novel therapeutics. Corneal disease is one of the most common causes of blindness. Hence, significant efforts are made to develop novel therapeutic approaches including stem cell-derived strategies to replace the diseased or damaged corneal tissues, thus restoring the vision. The use of adult limbal stem cells in the management of corneal conditions has been clinically successful. However, its limited availability and phenotypic plasticity necessitate the need for alternative stem cell sources to manage corneal conditions. Mesenchymal and embryonic stem cell-based approaches are being explored; nevertheless, their limited differentiation potential and ethical concerns have posed a significant hurdle in its clinical use. hiPSCs have emerged to fill these technical and ethical gaps to render clinical utility. In this review, we discuss and summarize protocols that have been devised so far to direct differentiation of human pluripotent stem cells (hPSCs) to different corneal cell phenotypes. With the summarization, our review intends to facilitate an understanding which would allow developing efficient and robust protocols to obtain specific corneal cell phenotype from hPSCs for corneal disease modeling and for the clinics to treat corneal diseases and injury.

The advances in CRISPR technology and 3D genome

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) system is a prokaryotic immune system that used to resist foreign genetic factors. It rapidly becomes the hot technology in life sciences and is applies for genome editing to solve the problem of genome-derived diseases. Using CRISPR/Cas technique, the biological DNA sequence can be repaired, cut, replaced, or added. It can effectively change the human stem cells and is expected to achieve results in the treatment. Compared with ZFN and TALEN genome editing techniques, CRISPR is more effective, accurate, and convenient. The application of CRISPR technique in three dimensional (3D) genome structure makes us understand the relationship between linear DNA sequence and 3D chromatin structure. Utilizing CRISPR/Cas9 genome editing to reverse or delete CTCF binding sites, to recognize changes of topological isomerism of the genome and interactions between chromatin loops. The purpose of this review is to introduce the characteristics and classification of the current CRISPR/Cas system, multiple functions, and potential therapeutic uses, as well as to outline the effect of the technique on chromatin loops by changing CTCF sites in 3D genomes. We will also briefly describe the importance of ethical dilemmas to be faced in CRISPR applications and provide a perspective for potential CRISPR considerations.

β Cell replacement: improving on the design

PURPOSE OF REVIEW

Here we summarize recent advancements in β cell replacement as a therapy for type 1 diabetes.

RECENT FINDINGS

β cell replacement therapy has been proposed as a cure for type 1 diabetes with the introduction of the Edmonton protocol for cadaveric islet transplantation. To allow widespread use of this approach, efforts have focused on establishing an abundant source of insulin-producing β cells, protecting transplanted cells from ischemia-mediated death, immune rejection, and re-occurring autoimmunity. Recent developments addressing these issues include generation of insulin-producing cells from human pluripotent stem cells, different encapsulation strategies and prevention of ischemia upon transplant.

SUMMARY

Despite significant advances in generating functional β cells from human pluripotent stem cells, several key challenges remain in regard to the survival of β cell grafts, protection from (auto-) immune destruction and implementation of additional safety mechanisms before a stem cell-based cell replacement therapy approach can be widely applied. Taking current findings into consideration, we outline a multilayered approach to design immune-privileged β cells from stem cells using state of the art genome editing technologies that if successfully incorporated could result in great benefit for diabetic patients and improve clinical results for cell replacement therapy.

Computational approaches for predicting key transcription factors in targeted cell reprogramming (Review)

There is a need for specific cell types in regenerative medicine and biological research. Frequently, specific cell types may not be easily obtained or the quantity obtained is insufficient for study. Therefore, reprogramming by the direct conversion (transdifferentiation) or re‑induction of induced pluripotent stem cells has been used to obtain cells expressing similar profiles to those of the desired types. Therefore, a specific cocktail of transcription factors (TFs) is required for induction. Nevertheless, identifying the correct combination of TFs is difficult. Although certain computational approaches have been proposed for this task, their methods are complex, and corresponding implementations are difficult to use and generalize for specific source or target cell types. In the present review four computational approaches that have been proposed to obtain likely TFs were compared and discussed. A simplified view of the computational complexity of these methods is provided that consists of three basic ideas: i) The definition of target and non‑target cell types; ii) the estimation of candidate TFs; and iii) filtering candidates. This simplified view was validated by analyzing a well‑documented cardiomyocyte differentiation. Subsequently, these reviewed methods were compared when applied to an unknown differentiation of corneal endothelial cells. The generated results may provide important insights for laboratory assays. Data and computer scripts that may assist with direct conversions in other cell types are also provided.

Anti-Inflamm-Ageing and/or Anti-Age-Related Disease Emerging Treatments: A Historical Alchemy or Revolutionary Effective Procedures?

The “long-life elixir” has long represented for humans a dream, a vanity's sin for remaining young and to long survive. Today, because of ageing population phenomenon, the research of antiageing interventions appears to be more important than ever, for preserving health in old age and retarding/or delaying the onset of age-related diseases. A hope is given by experimental data, which evidence the possibility of retarding ageing in animal models. In addition, it has been also demonstrated in animal life-extending studies not only the possibility of increasing longevity but also the ability to retard the onset of age-related diseases. Interestingly, this recent evidence is leading to promise of obtaining the same effects in humans and resulting in benefits for their health in old ages. In order to achieve this goal, different approaches have been used ranging from pharmacological targeting of ageing, basic biological assays, and big data analysis to the recent use of young blood, stem cells, cellular, genetic, and epigenetic reprogramming, or other techniques of regenerative medicine. However, only a little fraction of these approaches has the features for being tested in clinical applications. Here, new emerging molecules, drugs, and procedures will be described, by evidencing potential benefits and limitations.

Recent Progress in Stem Cell Modification for Cardiac Regeneration

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity.

Pyrimido[4,5-b]indole derivatives and use thereof in the expansion of hematopoietic stem cells US2015011543 (a1): a patent evaluation

INTRODUCTION

There is an unmet need of strategies for ex-vivo expansion of hematopoetic stem cells (HSCs) without loss of their primitive nature or stemness. We evaluate here a patent that attempts to address this need via key small molecules 1 and 40 that possess a pyrimido[4,5-b]indole core. Areas covered: (i) Discussion on literature reports of diverse strategies for ex-vivo expansion of stem cells. (ii) Synthetic scheme to 1, and general synthetic schemes for compounds 1-55 reported in the patent application. (iii) Analysis of the in vitro biological data for 1 and 40. Highlight here is: 1 and 40 when used in combination with StemReginin1 (SR1), an established aryl hydrocarbon receptor antagonist known for ex-vivo HSC expansion, demonstrate better HSC expansion relative to SR1 alone. (iv) Analysis of the in vivo biological data for 1 and 40. Expert opinion: Compelling evidence on the molecular mechanism of action of 1 and 40 is not provided making it difficult to optimize this series. It is suggested here that combining these molecules with homing molecules will possibly improve overall engraftment time and hematopoietic recovery. The numerous literature reports and biological data indicates that these pyrimido[4,5-b]indole derivatives are promising candidates for the development of potential therapies for hematopoietic ailments.