ETV5 is Essential for Neuronal Differentiation of Human Neural Progenitor Cells by Repressing NEUROG2 Expression Abstract Neural progenitor cells (NPCs) are multipotent cells that have the potential to produce neurons and glial cells in the neural system. NPCs undergo identity maintenance or differentiation regulated by different kinds of transcription factors. Here we present evidence that ETV5, which is an ETS transcription factor, promotes the generation of glial cells and drives the neuronal subtype-specific genes in newly differentiated neurons from the human embryonic stem cells-derived NPCs. Next, we find a new role for ETV5 in the repression of NEUROG2 expression in NPCs. ETV5 represses NEUROG2 transcription via NEUROG2 promoter and requires the ETS domain. We identify ETV5 has the binding sites and is implicated in silent chromatin in NEUROG2 promoter by chromatin immunoprecipitation (ChIP) assays. Further, NEUROG2 transcription repression by ETV5 was shown to be dependent on a transcriptional corepressor (CoREST). During NPC differentiation toward neurons, ETV5 represses NEUROG2 expression and blocks the appearance of glutamatergic neurons. This finding suggests that ETV5 negatively regulates NEUROG2 expression and increases the number of GABAergic subtype neurons derived from NPCs. Thus, ETV5 represents a potent new candidate protein with benefits for the generation of GABAergic neurons.

A Retrospective Analysis of Safety and Efficacy of Wharton’s Jelly Stem Cell Administration in Children with Spina Bifida Abstract The aim of this paper was to describe the outcome of therapeutic administration of mesenchymal stem cells (MSC) obtained from Wharton’s jelly (WJ-MSCs) in paediatric patients with spina bifida (SB) during a medical therapeutic experiment. We retrospectively analysed the records of twenty-eight patients aged 1–18 years (median age 4 years) recruited in daily clinical practice. Each patient received 0.9–5.0 × 106 WJ-MSCs/kg (median 2.6 × 106 WJ-MSCs/kg) administered in 1–5 injections as an experimental treatment for SB (allogenic administration). All the patients were examined by the same neurologist (study investigator, SI) on the day of each infusion. Based on the neurological examination, the SI used a six-point Likert scale to assess the quality of life and self-service of each patient. Twenty-six follow-up observations after MSC administration were analysed retrospectively. In addition, the assessments of the parents and other healthcare professionals were obtained for 5 patients and compared with the SI’s assessment. Twenty-one of 26 patients (81%) experienced some improvement in their health status. Twenty-one (81%) patients experienced increased quality of life (median 2.0) and 10 patients (38%) achieved a slight increase in their self-service level (median 1). Improvement was achieved in 12 out of 17 areas. Five were significant in low-power sign test: muscle tension, muscle strength, gross motor development, micturition/defecation control, and cognitive functions. Adverse events were mild and temporary. Age, body mass, single dose or poor response after the first administration were not significant predictors of later response to treatment in contrast to the total cell dose per one kg in the whole treatment course. WJ-MSC administration is a safe and effective procedure that improves motor functions, micturition/defecation control, and cognitive functions, and improves the quality of life in children with SB.

Gelatin Methacrylate (GelMA)-Based Hydrogels for Cell Transplantation: an Effective Strategy for Tissue Engineering Abstract Gelatin methacrylate (GelMA)-based hydrogels are gaining a great deal of attention as potentially implantable materials in tissue engineering applications because of their biofunctionality and mechanical tenability. Since different natural tissues respond differently to mechanical stresses, an ideal implanted material would closely match the mechanical properties of the target tissue. In this regard, applications employing GelMA hydrogels are currently limited by the low mechanical strength and biocompatibility of GelMA. Therefore, this review focuses on modifications made to GelMA hydrogels to make them more suitable for tissue engineering applications. A large number of reports detail rational synthetic processes for GelMA or describe the incorporation of various biomaterials into GelMA hydrogels to tune their various properties, e.g., physical strength, chemical properties, conductivity, and porosity, and to promote cell loading and accelerate tissue repair. A novel strategy for repairing tissue injuries, based on the transplantation of cell-loaded GelMA scaffolds, is examined and its advantages and challenges are summarized. GelMA-cell combinations play a critical and pioneering role in this process and could potentially accelerate the development of clinically relevant applications.

Biological Characteristics and Regulation of Early Megakaryocytopoiesis Abstract For decades, megakaryocytopoiesis is believed to occur following a classical binary hierarchical developmental model. This model is based on an analysis of predefined flow-sorted cell populations by using cell surface markers. However, this classical model has been challenged by increasing evidences obtained with new techniques which integrating flow cytometric, transcriptomic and functional data at single-cell level and with lineage tracing technique. These recent advances in megakaryocytopoiesis proposed that commitment of haematopoietic stem cells (HSCs) towards megakaryocytic lineage occurs in much earlier stage than that postulated in the classical model. There may exist multipotent but megakaryocyte (MK)/platelet-biased HSCs within HSC compartment and even HSCs can directly differentiate into MKs in steady state or in response to stress. In this review, we focus on recent findings about differentiation from commitment of HSCs to MK and its regulation, and discuss future directions in this research field.

Characterization and Isolation of Very Small Embryonic-like (VSEL) Stem Cells Obtained from Various Human Hematopoietic Cell Sources Abstract Stem cell transplantation is one of the available treatments for leukemia, lymphoma, hereditary blood diseases and bone marrow failure. Bone marrow (BM), peripheral blood progenitor cells (PBPC), and cord blood (CB) are the predominant sources of stem cells. Recently a new type of stem cell with a pluripotent potential has been identified. These cells were named “very small embryonic like stem cells (VSELs)”. It is claimed that VSEL stem cells can be found in adult BM, peripheral blood (PB), CB and other body tissues. This study is designed to characterize and isolate VSEL stem cells from different human hematopoietic sources; CB, PB and apheresis material (PBPC). VSEL stem cells were isolated from MNC and erythrocyte layers for all materials by using centrifugation and ficoll gradient method. We determined embryonic markers by flow cytometry, immunofluorescence and western blotting methods. Results from western blotting and immunofluorescence show high level of NANOG and OCT4 protein expression in PB, apheresis material and CB. Immunofluorescence images showed cytoplasmic and nuclear presence of these proteins. Flow cytometry results exhibited a higher expression of VSELs markers on debris area than CD45- population and higher expression on CB than PB. As a result, these findings have shown that it is necessary to investigate the function of pluripotent stem cell markers in differentiated adult cells. We further conclude that erythrocyte lysis method had the highest cell recovery amount among erythrocyte lysis and ficoll gradient methods. Consequently, this study gives us new information and viewpoints about expression of pluripotent stem cell (PSC) markers in adult tissues.

Reprogramming of Keratinocytes as Donor or Target Cells Holds Great Promise for Cell Therapy and Regenerative Medicine Abstract One of the most crucial branches of regenerative medicine is cell therapy, in which cellular material is injected into the patient to initiate the regenerative process. Cells obtained by reprogramming of the patient’s own cells offer ethical and clinical advantages could provide a new source of material for therapeutic applications. Studies to date have shown that only a subset of differentiated cell types can be reprogrammed. Among these, keratinocytes, which are the most abundant proliferating cell type in the epidermis, have gained increasing attention as both donor and target cells for reprogramming and have become a new focus of regenerative medicine. As target cells for the treatment of skin defects, keratinocytes can be differentiated or reprogrammed from embryonic stem cells, induced pluripotent stem cells, fibroblasts, adipose tissue stem cells, and mesenchymal cells. As donor cells, keratinocytes can be reprogrammed or direct reprogrammed into a number of cell types, including induced pluripotent stem cells, neural cells, and Schwann cells. In this review, we discuss recent advances in keratinocyte reprogramming, focusing on the induction methods, potential molecular mechanisms, conversion efficiency, and safety for clinical applications. Graphical Abstract KCs as target cells can be reprogrammed or differentiated from fibroblasts, iPSCs, ATSCs, and mesenchymal cells. And as donor cells, KCs can be reprogrammed or directly reprogrammded into iPSCs, neural cells, Schwann cells, and epidermal stem cells.

Heat Shock Proteins and their Protective Roles in Stem Cell Biology Abstract Stem cells (SCs) are discovered long back but the idea that SCs possess therapeutic potential came up just a few decades back. In a past decade stem cell therapy is highly emerged and displayed tremendous potential for the treatment of a wide range of diseases and disorders such as blindness and vision impairment, type I diabetes, infertility, HIV, etc. SCs are very susceptible to destruction after transplantation into the host because of the inability to sustain elevated stress conditions inside the damaged tissue/organ. Heat shock proteins (HSPs) are molecular chaperones/stress proteins expressed in response to stress (elevated temperature, harmful chemicals, ischemia, viruses, etc) inside a living cell. HSPs protect the cell from damage by assisting in the proper folding of cellular proteins. This review briefly summarises different types of HSPs, their classification, cellular functions as well as the role of HSPs in regulating SC self-renewal and survival in the transplanted host. Applications of HSP modulated SCs in regenerative medicine and for the treatment of ischemic heart disease, myocardial infarction (MI), osteoarthritis, ischemic stroke, spinocerebellar ataxia type 3 (SCA3), leukemia, hepatic ischemia-reperfusion injury, Graft-versus-host disease (GVHD) and Parkinson’s disease (PD) are discussed. In order to provide potential insights in understanding molecular mechanisms related to SCs in vertebrates, correlations between HSPs and SCs in cnidarians and planarians are also reviewed. There is a need to advance research in order to validate the use of HSPs for SC therapy and establish effective treatment strategies.

miR-22-5p and miR-29a-5p Are Reliable Reference Genes for Analyzing Extracellular Vesicle-Associated miRNAs in Adipose-Derived Mesenchymal Stem Cells and Are Stable under Inflammatory Priming Mimicking Osteoarthritis Condition Abstract During the last two decades, mesenchymal stem cells (MSCs) gained a place of privilege in the field of regenerative medicine. Recently, extracellular vesicles (EVs) have been identified as major mediators of MSCs immunosuppressive as well as pro-regenerative activities in many disease models, including inflammatory/degenerative conditions as joint diseases and osteoarthritis. In order to shed light on EVs potential, a rigorous profiling of embedded proteins, lipids and nucleic acids (mRNA/miRNA) is mandatory. Nevertheless, reliable strategies to efficiently score miRNA cargo and modulation under diverse experimental conditions or treatments are missing. The aim of this work was to identify reliable reference genes (RGs) to analyze miRNA content in EVs secreted by adipose-derived MSCs (ASCs) and verify their consistency under inflammatory conditions that were proposed to enhance ASC-EVs immunomodulatory and regenerative potential. RefFinder algorithm, that integrates the currently available major computational programs (geNorm, NormFinder, BestKeeper, and Delta Ct method), allowed to identify miR-22-5p and miR-29a-5p as the most stable RGs. Notably, both miRNAs maintained the highest stability when EVs isolated from IFNg-treated ASCs were included in the analysis. In addition, considerable effects of suboptimal RGs choice on the reliable quantification of miRNAs involved at different levels (tissue homeostasis or macrophage polarization) in the osteoarthritis phenotype, and thus considered as promising therapeutic molecule, have clearly been demonstrated. In conclusion, a proper normalization method is not only needed for research purposes but also mandatory to characterize clinical products and predict their therapeutic potential, especially in the emerging field of MSCs derived-EVs as new tools for regenerative medicine.

A Gutsy Move for Cell-Based Regenerative Medicine in Parkinson’s Disease: Targeting the Gut Microbiome to Sequester Inflammation and Neurotoxicity Abstract Pharmaceuticals and cell-based regenerative medicine for Parkinson’s disease (PD) offer palliative relief but do not arrest the disease progression. Cell therapy has emerged as an experimental treatment, but current cell sources such as human umbilical cord blood (hUCB) stem cells display only partial recapitulation of mature dopaminergic neuron phenotype and function. Nonetheless, stem cell grafts ameliorate PD-associated histological and behavioral deficits likely through stem cell graft-secreted therapeutic substances. We recently demonstrated the potential of hUCB-derived plasma in enhancing motor capabilities and gastrointestinal function, as well as preventing dopaminergic neuronal cell loss, in an 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP) rodent model of PD. Recognizing the translational need to test in another PD model, we now examined here the effects of an intravenously transplanted combination of hUCB and plasma into the 6-hydroxydopamine (6-OHDA) lesioned adult rats. Animals received three separate doses of 4 × 106 hUCB cells with plasma beginning at 7 days after stereotaxic 6-OHDA lesion, then behaviorally and immunohistochemically evaluated over 56 days post-lesion. Whereas vehicle-treated lesioned animals exhibited the typical 6-OHDA neurobehavioral symptoms, hUCB and plasma-treated lesioned animals showed significant attenuation of motor function, gut motility, and nigral dopaminergic neuronal survival, combined with diminished pro-inflammatory microbiomes not only in the nigra, but also in the gut. Altogether these data support a regenerative medicine approach for PD by sequestering inflammation and neurotoxicity through correction of gut dysbiosis.

Solid Tumors Challenges and New Insights of CAR T Cell Engineering Abstract Adoptive cell therapy using CAR T cells has emerged as a novel treatment strategy with promising results against B cell malignancies; however, CAR T cells have not shown much success against solid malignancies. There are several obstacles which diminish the efficacy of CAR T cells, but the immunosuppressive tumor microenvironment (TME) of the tumor stands out as the most important factor. TME includes Tumor-Associated Stroma, Immunosuppressive cells and cytokines, tumor hypoxia and metabolism, and Immune Inhibitory Checkpoints which affect the CAR T cell efficacy and activity in solid tumors. A precise understanding of the TME could pave the way to engineer novel modifications of CAR T cells which can overcome the immunosuppressive TME. In this review, we will describe different sections of the TME and introduce novel approaches to improve the CAR T cells potential against solid tumors based on recent clinical and preclinical data. Also, we will provide new suggestions on how to modify CARs to augment of CAR T cells efficacy. Since there are also some challenges beyond the TME that are important for CAR function, we will also discuss and provide data about the improvement of CAR T cells trafficking and delivery to the tumor site and how to solve the problem of tumor antigen heterogeneity.