Role of brahma-related gene 1/brahma-associated factor subunits in neural stem/progenitor cells and related neural developmental disorders

Different fates of neural stem/progenitor cells(NSPCs)and their progeny are determined by the gene regulatory network,where a chromatin-remodeling complex affects synergy with other regulators.Here,we review recent research progress indicating that the BRG1/BRM-associated factor(BAF)complex plays an important role in NSPCs during neural development and neural developmental disorders.Several studies based on animal models have shown that mutations in the BAF complex may cause abnormal neural differentiation,which can also lead to various diseases in humans.We discussed BAF complex subunits and their main characteristics in NSPCs.With advances in studies of human pluripotent stem cells and the feasibility of driving their differentiation into NSPCs,we can now investigate the role of the BAF complex in regulating the balance between self-renewal and differentiation of NSPCs.Considering recent progress in these research areas,we suggest that three approaches should be used in investigations in the near future.Sequencing of whole human exome and genome-wide association studies suggest that mutations in the subunits of the BAF complex are related to neurodevelopmental disorders.More insight into the mechanism of BAF complex regulation in NSPCs during neural cell fate decisions and neurodevelopment may help in exploiting new methods for clinical applications.

Hypoxic pre-conditioned adipose-derived stem/progenitor cells embedded in fibrin conduits promote peripheral nerve regeneration in a sciatic nerve graft model

Recent results emphasize the supportive effects of adipose-derived multipotent stem/progenitor cells(ADSPCs)in peripheral nerve recovery.Cultivation under hypoxia is considered to enhance the release of the regenerative potential of ADSPCs.This study aimed to examine whether peripheral nerve regeneration in a rat model of autologous sciatic nerve graft benefits from an additional custom-made fibrin conduit seeded with hypoxic pre-conditioned(2%oxygen for 72 hours)autologous ADSPCs(n=9).This treatment mode was compared with three others:fibrin conduit seeded with ADSPCs cultivated under normoxic conditions(n=9);non-cell-carrying conduit(n=9);and nerve autograft only(n=9).A 16-week follow-up included functional testing(sciatic functional index and static sciatic index)as well as postmortem muscle mass analyses and morphometric nerve evaluations(histology,g-ratio,axon density,and diameter).At 8 weeks,the hypoxic pre-conditioned group achieved significantly higher sciatic functional index/static sciatic index scores than the other three groups,indicating faster functional regeneration.Furthermore,histologic evaluation showed significantly increased axon outgrowth/branching,axon density,remyelination,and a reduced relative connective tissue area.Hypoxic pre-conditioned ADSPCs seeded in fibrin conduits are a promising adjunct to current nerve autografts.Further studies are needed to understand the underlying cellular mechanism and to investigate a potential application in clinical practice.

Transplantation of vascular endothelial growth factor-modified neural stem/progenitor cells promotes the recovery of neurological function following hypoxic-ischemic brain damage

Neural stem/progenitor cell （NSC） transplantation has been shown to effectively improve neurological function in rats with hypoxic-isch- emic brain damage. Vascular endothelial growth factor （VEGF） is a signaling protein that stimulates angiogenesis and improves neural regeneration. We hypothesized that transplantation of VEGF-transfected NSCs would alleviate hypoxic-ischemic brain damage in neo- natal rats. We produced and transfected a recombinant lentiviral vector containing the VEGF165gene into cultured NSCs. The transfected NSCs were transplanted into the left sensorimotor cortex of rats 3 days after hypoxic-ischemic brain damage. Compared with the NSCs group, VEGF mRNA and protein expression levels were increased in the transgene NSCs group, and learning and memory abilities were significantly improved at 30 days. Furthermore, histopathological changes were alleviated in these animals. Our findings indicate that transplantation of VEGF-transfected NSCs may facilitate the recovery of neurological function, and that its therapeutic effectiveness is better than that of unmodified NSCs.

Transcriptional regulation of adult neural stem/progenitor cells: tales from the subventricular zone

In rodents,well characterized neurogenic niches of the adult brain,such as the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampus,support the maintenance of neural/stem progenitor cells(NSPCs)and the production of new neurons throughout the lifespan.The adult neurogenic process is dependent on the intrinsic gene expression signatures of NSPCs that make them competent for self-renewal and neuronal differentiation.At the same time,it is receptive to regulation by various extracellular signals that allow the modulation of neuronal production and integration into brain circuitries by various physiological stimuli.A drawback of this plasticity is the sensitivity of adult neurogenesis to alterations of the niche environment that can occur due to aging,injury or disease.At the core of the molecular mechanisms regulating neurogenesis,several transcription factors have been identified that maintain NSPC identity and mediate NSPC response to extrinsic cues.Here,we focus on REST,Egr1 and Dbx2 and their roles in adult neurogenesis,especially in the subventricular zone.We review recent work from our and other laboratories implicating these transcription factors in the control of NSPC proliferation and differentiation and in the response of NSPCs to extrinsic influences from the niche.We also discuss how their altered regulation may affect the neurogenic process in the aged and in the diseased brain.Finally,we highlight key open questions that need to be addressed to foster our understanding of the transcriptional mechanisms controlling adult neurogenesis.

Ultrastructure of human neural stem/progenitor cells and neurospheres

BACKGROUND： Biological and morphological characteristics of neural stem/progenitor cells （NSPCs） have been widely investigated. OBJECTIVE： To explore the ultrastructure of human embryo-derived NSPCs and neurospheres cultivated in vitro using electron microscopy. DESIGN, TIME AND SETTING： A cell biology experiment was performed at the Brain Tumor Laboratory of Soochow University, and Jiangsu Province Key Laboratory of Neuroregeneration, Nantong University between August 2007 and April 2008. MATERIALS： Human fetal brain tissue was obtained from an 8-week-old aborted fetus; serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium was provided by Gibco, USA; scanning electron microscope was provided by Hitachi Instruments, Japan; transmission electron microscope was provided by JEOL, Japan. METHODS： NSPCs were isolated from human fetal brain tissue and cultivated in serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium. Cells were passaged every 5-7 days. After three passages, NSPCs were harvested and used for ultrastructural examination. MAIN OUTCOME MEASURES： Ultrastructural examination of human NSPCs and adjacent cells in neurospheres. RESULTS： Individual NSPCs were visible as spherical morphologies with rough surfaces under scanning electron microscope. Generally, they had large nuclei and little cytoplasm. Nuclei were frequently globular with large amounts of euchromatin and a small quantity of heterochromatin, and most NSPCs had only one nucleolus. The Golgi apparatus and endoplasmic reticulum were underdeveloped; however, autophagosomes were clearly visible. The neurospheres were made up of NSPCs and non-fixiform material inside. Between adjacent cells and at the cytoplasmic surface of apposed plasma membranes, there were vesicle-like structures. Some membrane boundaries with high permeabilities were observed between some contiguous NSPCs in neurospheres, possibly attributable to plasmalemmal fusion between adjacent cells. CONCLUSION： A large number of autophagosomes were observed in NSPCs and gap junctions were visible between adjacent NSPCs.

PRELIMINARY STUDY OF RETROVIRAL MEDIATED TRANSFER OF THE HUMAN mdr-1 GENE INTO MURINE AND HUMAN HEMATOPOIETIC STEM/PROGENITOR CELLS

To investigate the characteristics of multidrugresistance and transplantation of modified stem/ progenitor cells by multidrugresistant gene (mdr1 gene), we established PA317/MDR1 cell line which producing retroviruses by transfecting the retroviral vector PHaMDR1/A into packging cell line PA317 by Lipofectin. The virus titer of the supernatants was 1.2×105 cfu/ml. We transfected the murine hematopietic cells collected from 5FU pretreated mice and they showed the ability to reconstitute the longterm hematopoiesis of preirradiated mice. After 4 months, both of bone marrow cells and peripheral blood cells of transplanted mice still contained mdr1 gene. We also transfered mdr1 gene into human bone marrow CD34+ cells selected by using magnetic cell sorting system. PCR analysis showed that transduced CD34+ cells maintained the mdr1 cDNA. A fraction of CFUGM originated from transfected CD34+ cells had the charactor of resistance to Taxol. It is indicated that mdr1 gene can be transduced into murine and human stem/proginitor cells through retroviral mediated gene transfer and it protects the transfected cells from cytotoxic drugs.

Perspectives on mesenchymal stem/progenitor cells and their derivates as potential therapies for lung damage caused by COVID-19

The new coronavirus,severe acute respiratory syndrome coronavirus-2(SARSCoV-2),which emerged in December 2019 in Wuhan,China,has reached worldwide pandemic proportions,causing coronavirus disease 2019(COVID-19).The clinical manifestations of COVID-19 vary from an asymptomatic disease course to clinical symptoms of acute respiratory distress syndrome and severe pneumonia.The lungs are the primary organ affected by SARS-CoV-2,with a very slow turnover for renewal.SARS-CoV-2 enters the lungs via angiotensinconverting enzyme 2 receptors and induces an immune response with the accumulation of immunocompetent cells,causing a cytokine storm,which leads to target organ injury and subsequent dysfunction.To date,there is no effective antiviral therapy for COVID-19 patients,and therapeutic strategies are based on experience treating previously recognized coronaviruses.In search of new treatment modalities of COVID-19,cell-based therapy with mesenchymal stem cells(MSCs)and/or their secretome,such as soluble bioactive factors and extracellular vesicles,is considered supportive therapy for critically ill patients.Multipotent MSCs are able to differentiate into different types of cells of mesenchymal origin,including alveolar epithelial cells,lung epithelial cells,and vascular endothelial cells,which are severely damaged in the course of COVID-19 disease.Moreover,MSCs secrete a variety of bioactive factors that can be applied for respiratory tract regeneration in COVID-19 patients thanks to their trophic,anti-inflammatory,immunomodulatory,anti-apoptotic,pro-regenerative,and proangiogenic properties.

The advantages of multi-level omics research on stem cell-based therapies for ischemic stroke

Stem cell transplantation is a potential therapeutic strategy for ischemic stroke. However, despite many years of preclinical research, the application of stem cells is still limited to the clinical trial stage. Although stem cell therapy can be highly beneficial in promoting functional recovery, the precise mechanisms of action that are responsible for this effect have yet to be fully elucidated. Omics analysis provides us with a new perspective to investigate the physiological mechanisms and multiple functions of stem cells in ischemic stroke. Transcriptomic, proteomic, and metabolomic analyses have become important tools for discovering biomarkers and analyzing molecular changes under pathological conditions. Omics analysis could help us to identify new pathways mediated by stem cells for the treatment of ischemic stroke via stem cell therapy, thereby facilitating the translation of stem cell therapies into clinical use. In this review, we summarize the pathophysiology of ischemic stroke and discuss recent progress in the development of stem cell therapies for the treatment of ischemic stroke by applying multi-level omics. We also discuss changes in RNAs, proteins, and metabolites in the cerebral tissues and body fluids under stroke conditions and following stem cell treatment, and summarize the regulatory factors that play a key role in stem cell therapy. The exploration of stem cell therapy at the molecular level will facilitate the clinical application of stem cells and provide new treatment possibilities for the complete recovery of neurological function in patients with ischemic stroke.

Advanced glycation end productions and tendon stem/progenitor cells in pathogenesis of diabetic tendinopathy

Tendinopathy is a challenging complication observed in patients with diabetes mellitus.Tendinopathy usually leads to chronic pain,limited joint motion,and even ruptured tendons.Imaging and histological analyses have revealed pathological changes in various tendons of patients with diabetes,including disorganized arrangement of collagen fibers,microtears,calcium nodules,and advanced glycation end product(AGE)deposition.Tendon-derived stem/progenitor cells(TSPCs)were found to maintain hemostasis and to participate in the reversal of tendinopathy.We also discovered the aberrant osteochondrogenesis of TSPCs in vitro.However,the relationship between AGEs and TSPCs in diabetic tendinopathy and the underlying mechanism remain unclear.In this review,we summarize the current findings in this field and hypothesize that AGEs could alter the properties of tendons in patients with diabetes by regulating the proliferation and differentiation of TSPCs in vivo.

Establishment of a humanized mouse model using steady-state peripheral blood-derived hematopoietic stem and progenitor cells facilitates screening of cancer-targeted T-cell repertoires

Background:Cancer-targeted T-cell receptor T(TCR-T)cells hold promise in treating cancers such as hematological malignancies and breast cancers.However,approaches to obtain cancer-reactive TCR-T cells have been unsuccessful.Methods:Here,we developed a novel strategy to screen for cancer-targeted TCR-T cells using a special humanized mouse model with person-specific immune fingerprints.Rare steady-state circulating hematopoietic stem and progenitor cells were expanded via three-dimensional culture of steady-state peripheral blood mononuclear cells,and then the expanded cells were applied to establish humanized mice.The human immune system was evaluated according to the kinetics of dendritic cells,monocytes,T-cell subsets,and cytokines.To fully stimulate the immune response and to obtain B-cell precursor NAML-6-and triple-negative breast cancer MDA-MB-231-targeted TCR-T cells,we used the inactivated cells above to treat humanized mice twice a day every 7 days.Then,human T cells were processed for TCRβ-chain(TRB)sequencing analysis.After the repertoires had been constructed,features such as the fraction,diversity,and immune signature were investigated.Results:The results demonstrated an increase in diversity and clonality of T cells after treatment.The preferential usage and features of TRBV,TRBJ,and the V–J combination were also changed.The stress also induced highly clonal Science and Technology,Grant/Award Number:2021C03010;Zhejiang Provincial Natural Science Foundation of China,Grant/Award Numbers:LTGY24H080003,LY21H080004 expansion.Tumor burden and survival analysis demonstrated that stress induction could significantly inhibit the growth of subsequently transfused live tumor cells and prolong the survival of the humanized mice.Conclusions:We constructed a personalized humanized mouse model to screen cancer-targeted TCR-T pools.Our platform provides an effective source of cancer-targeted TCR-T cells and allows for the design of patient-specific engineered T cells.It therefore has the potential to greatly benefit cancer treatment.

Induced Differentiation of Human Cord Blood Mesenchymal Stem/Pro genitor Cells into Cardiomyocyte-like Cells In Vitro

The feasibility of using cord blood mesenchymal stem/progenitor cells (CB-MSPCs) to regenerate cardiomyocytes and the optimal inducing conditions were investigated. The CB mononuclear cells were cultured in low serum DMEM medium to produce an adherent layer. After expansion, the adherent cells were added into cardiomyocyte inducing medium supplemented with 5-azacytidine. Cardiogenic specific contractile protein troponin T staining was performed to identify the cardiomy-ocyte-like cells. The results showed that the frequency of CB-MSPCs clones in CB mononuclear cells was 0. 5×10-6 and about 1. 3×107-fold expansion was achieved within 20 sub-cultivation. After car-diogenic induction, 70 % CB-MSPCs was differentiated into cardiomyocyte-like cells. It was indicated that low serum culture could expand CB-MSPCs extensively and the expanded CB-MSPCs could be induced to differentiate into cardiomyocyte-like cells in high efficiency.

Cell-based therapies for neural replacement strategies in stroke-related neurodegeneration： neurophysiological insights into stem progenitor cell neurogenesis within a host environment

The restricted neurogenesis limits the brain ability to overcome neuronal cell death following ischemic lesion：Failure of the damaged brain to regenerate following cerebral ischemia results in functional deficits those are most often irreversible and can further deteriorate,causing mortality and severe disability,progressive memory loss and cognitive impairments,known as dementia.

Regulation of neural stem/progenitor cell functions by P2X and P2Y receptors

Neural stem/progenitor cells：Radial glial cells constitute multipotent cells in the ventricular zone,lining the wall of the lateral ventricle of the embryonic brain.They have the capacity to give rise to cells belonging to all three major linages（neurons,astrocytes and oligodendrocytes）of the nervous system（Tang and Illes,2017）.

Cardiac stem cells: Current knowledge and future prospects

Regenerative medicine is the field concerned with the repair and restoration of the integrity of damaged human tissues as well as whole organs.Since the inception of the field several decades ago,regenerative medicine therapies,namely stem cells,have received significant attention in preclinical studies and clinical trials.Apart from their known potential for differentiation into the various body cells,stem cells enhance the organ's intrinsic regenerative capacity by altering its environment,whether by exogenous injection or introducing their products that modulate endogenous stem cell function and fate for the sake of regeneration.Recently,research in cardiology has highlighted the evidence for the existence of cardiac stem and progenitor cells(CSCs/CPCs).The global burden of cardiovascular diseases’morbidity and mortality has demanded an in-depth understanding of the biology of CSCs/CPCs aiming at improving the outcome for an innovative therapeutic strategy.This review will discuss the nature of each of the CSCs/CPCs,their environment,their interplay with other cells,and their metabolism.In addition,important issues are tackled concerning the potency of CSCs/CPCs in relation to their secretome for mediating the ability to influence other cells.Moreover,the review will throw the light on the clinical trials and the preclinical studies using CSCs/CPCs and combined therapy for cardiac regeneration.Finally,the novel role of nanotechnology in cardiac regeneration will be explored.

Identification of a Native Novel Oncolytic Immunoglobulin on Exfoliated Colon Epithelial Cells: A Bispecific Heterodimeric Chimera of IgA/IgG*

Understanding the nature of cell surface markers on exfoliated colonic cells is a crucial step in establishing criteria for a normally functioning mucosa. We have found that colonic cells isolated from stool samples (SCSR-010 Fecal Cell Isolation Kit, NonInvasive Technologies, Elkridge, MD), preserved at room temperature for up to one week, with viability of >85% and low levels of apoptosis (8% - 10%) exhibit two distinct cell size subpopulations, in the 2.5 μM - 5.0 μM and 5.0 μM - 8.0 μM range. In addition to IgA, about 60% of the cells expressed a novel heterodimeric IgA/IgG immunoglobulin that conferred a broad-spectrum cell mediated cytotoxicity against tumor cells. In a cohort of 58 subjects the exclusive absence of this immunoglobulin in two African-Americans was suggestive of a germline deletion. Serial cultures in stem cell medium retained the expression of this heterodimer. Since a majority of the cystic cells expressed the stem cell markers Lgr5 and Musashi-1 we termed these cells as gastrointestinal progenitor stem cells (GIP-C**). CXCR-4, the cytokine co-receptor for HIV was markedly expressed. These cells also expressed CD20, IgA, IgG, CD45, and COX-2. We assume that they originated from mature columnar epithelium by dedifferentiation. Our observations indicate that we have a robust noninvasive method to study mucosal pathophysiology and a direct method to create a database for applications in regenerative medicine.

Engineered biochemical cues of regenerative biomaterials to enhance endogenous stem/progenitor cells(ESPCs)-mediated articular cartilage repair

As a highly specialized shock-absorbing connective tissue,articular cartilage(AC)has very limited self-repair capacity after traumatic injuries,posing a heavy socioeconomic burden.Common clinical therapies for small-to medium-size focal AC defects are well-developed endogenous repair and cell-based strategies,including microfracture,mosaicplasty,autologous chondrocyte implantation(ACI),and matrix-induced ACI(MACI).However,these treatments frequently result in mechanically inferior fibrocartilage,low cost-effectiveness,donor site morbidity,and short-term durability.It prompts an urgent need for innovative approaches to pattern a pro-regenerative microenvironment and yield hyaline-like cartilage with similar biomechanical and biochemical properties as healthy native AC.Acellular regenerative biomaterials can create a favorable local environment for AC repair without causing relevant regulatory and scientific concerns from cell-based treatments.A deeper understanding of the mechanism of endogenous cartilage healing is furthering the(bio)design and application of these scaffolds.Currently,the utilization of regenerative biomaterials to magnify the repairing effect of joint-resident endogenous stem/progenitor cells(ESPCs)presents an evolving improvement for cartilage repair.This review starts by briefly summarizing the current understanding of endogenous AC repair and the vital roles of ESPCs and chemoattractants for cartilage regeneration.Then several intrinsic hurdles for regenerative biomaterials-based AC repair are discussed.The recent advances in novel(bio)design and application regarding regenerative biomaterials with favorable biochemical cues to provide an instructive extracellular microenvironment and to guide the ESPCs(e.g.adhesion,migration,proliferation,differentiation,matrix production,and remodeling)for cartilage repair are summarized.Finally,this review outlines the future directions of engineering the next-generation regenerative biomaterials toward ultimate clinical translation.

road to stemness in hepatocellular carcinoma

Carcinogenic process has been proposed to relay on the capacity to induce local tissue damage and proliferative repair. Liver has a great regeneration capacity and currently, most studies point towards the dominant role of hepatocytes in regeneration at all levels of liver damage. The most frequent liver cancer is hepatocellular carcinoma(HCC). Historical findings originally led to the idea that the cell of origin of HCC might be a progenitor cell. However, current linage tracing studies put the progenitor hypothesis of HCC origin into question. In agreement with their dominant role in liver regeneration, mature hepatocytes are emerging as the cell of origin of HCC, although, the specific hepatocyte subpopulation of origin is yet to be determined. The relationship between the cancer cell of origin(CCO) and cancer-propagating cells, known as hepatic cancer stem cell(HCSC) is unknown. It has been challenging to identify the definitive phenotypic marker of HCSC, probably due to the existence of different cancer stem cells(CSC) subpopulations with different functions within HCC. There is a dynamic interconversion among different CSCs, and between CSC and non-CSCs. Because of that, CSC-state is currently defined as a description of a highly adaptable and dynamic intrinsic property of tumor cells, instead of a static subpopulation of a tumor. Altered conditions could trigger the gain of stemness, some of them include: EMT-MET, epigenetics, microenvironment and selective stimulus such as chemotherapy. This CSC heterogeneity and dynamism makes them out reach from therapeutic protocols directed to a single target. A further avenue of research in this line will be to uncover mechanisms that trigger this interconversion of cell populations within tumors and target it.

Validation of a novel animal model for sciatic nerve repair with an adipose-derived stem cell loaded fibrin conduit

Despite the regenerative capabilities of peripheral nerves, severe injuries or neuronal trauma of critical size impose immense hurdles for proper restoration of neuro-muscular circuitry. Autologous nerve grafts improve re-establishment of connectivity, but also comprise substantial donor site morbidity. We developed a rat model which allows the testing of different cell applications, i.e., mesenchymal stem cells, to improve nerve regeneration in vivo. To mimic inaccurate alignment of autologous nerve grafts with the injured nerve, a 20 mm portion of the sciatic nerve was excised, and sutured back in place in reversed direction. To validate the feasibility of our novel model, a fibrin gel conduit containing autologous undifferentiated adipose-derived stem cells was applied around the coaptation sites and compared to autologous nerve grafts. After evaluating sciatic nerve function for 16 weeks postoperatively, animals were sacrificed, and gastrocnemius muscle weight was determined along with morphological parameters（g-ratio, axon density ＆ diameter） of regenerating axons. Interestingly, the addition of undifferentiated adipose-derived stem cells resulted in a significantly improved re-myelination, axon ingrowth and functional outcome, when compared to animals without a cell seeded conduit. The presented model thus displays several intriguing features： it imitates a certain mismatch in size, distribution and orientation of axons within the nerve coaptation site. The fibrin conduit itself allows for an easy application of cells and, as a true critical-size defect model, any observed improvement relates directly to the performed intervention. Since fibrin and adipose-derived stem cells have been approved for human applications, the technique can theoretically be performed on humans. Thus, we suggest that the model is a powerful tool to investigate cell mediated assistance of peripheral nerve regeneration.