Adult Tissue Stem Cells Research Articles

Comparison between USPIOs and SPIOs for Multimodal Imaging of Extracellular Vesicles Extracted from Adipose Tissue-Derived Adult Stem Cells.

Adipose tissue-derived adult stem (ADAS) cells and extracellular vesicle (EV) therapy offer promising avenues for treating neurodegenerative diseases due to their accessibility and potential for autologous cell transplantation. However, the clinical application of ADAS cells or EVs is limited by the challenge of precisely identifying them in specific regions of interest. This study compares two superparamagnetic iron oxide nanoparticles, differing mainly in size, to determine their efficacy for allowing non-invasive ADAS tracking via MRI/MPI and indirect labeling of EVs. We compared a USPIO (about 5 nm) with an SPIO (Resovist®, about 70 nm). A physicochemical characterization of nanoparticles was conducted using DLS, TEM, MRI, and MPI. ADAS cells were labeled with the two nanoparticles, and their viability was assessed via MTT assay. MRI detected labeled cells, while TEM and Prussian Blue staining were employed to confirm cell uptake. The results revealed that Resovist® exhibited higher transversal relaxivity value than USPIO and, consequently, allows for detection with higher sensitivity by MRI. A 200 µgFe/mL concentration was identified as optimal for ADAS labeling. MPI detected only Resovist®. The findings suggest that Resovist® may offer enhanced detection of ADAS cells and EVs, making it suitable for multimodal imaging. Preliminary results obtained by extracting EVs from ADAS cells labeled with Resovist® indicate that EVs retain the nanoparticles, paving the way to an efficient and multimodal detection of EVs.

GVHD targets organoid-forming bile duct stem cells in a TGF-β–dependent manner

AbstractGraft-versus-host disease (GVHD) is a major life-threatening complication that occurs after allogeneic hematopoietic cell transplantation (HCT). Although adult tissue stem cells have been identified as targets of GVHD in the skin and gut, their role in hepatic GVHD is yet to be clarified. In the current study, we explored the fate of bile duct stem cells (BDSCs), capable of generating liver organoids in vitro, during hepatic GVHD after allogeneic HCT. We observed a significant expansion of biliary epithelial cells (BECs) on injury early after allogeneic HCT. Organoid-forming efficiency from the bile duct was also significantly increased early after allogeneic HCT. Subsequently, the organoid-forming efficiency from bile ducts was markedly decreased in association with the reduction of BECs and the elevation of plasma concentrations of bilirubin, suggesting that GVHD targets BDSCs and impairs the resilience of BECs. The growth of liver organoids in the presence of liver-infiltrating mononuclear cells from allogeneic recipients, but not from syngeneic recipients, was significantly reduced in a transforming growth factor-β (TGF-β)–dependent manner. Administration of SB-431542, an inhibitor of TGF-β signaling, from day 14 to day 28, protected organoid-forming BDSCs against GVHD and mitigated biliary dysfunction after allogeneic HCT, suggesting that BDSCs are a promising therapeutic target for hepatic GVHD.

The extracellular matrix niche of muscle stem cells.

Preserving the potency of stem cells in adult tissues is very demanding and relies on the concerted action of various cellular and non-cellular elements in a precise stoichiometry. This balanced microenvironment is found in specific anatomical "pockets" within the tissue, known as the stem cell niche. In this review, we explore the interplay between stem cells and their niches, with a primary focus on skeletal muscle stem cells and the extracellular matrix (ECM). Quiescent muscle stem cells, known as satellite cells are active producers of a diverse array of ECM molecules, encompassing major constituents like collagens, laminins, and integrins, some of which are explored in this review. The conventional perception of ECM as merely a structural scaffold is evolving. Collagens can directly interact as ligands with receptors on satellite cells, while other ECM proteins have the capacity to sequester growth factors and regulate their release, especially relevant during satellite cell turnover in homeostasis or activation upon injury. Additionally, we explore an evolutionary perspective on the ECM across a range of multicellular organisms and discuss a model wherein satellite cells are self-sustained by generating their own niche. Considering the prevalence of ECM proteins in the connective tissue of various organs it is not surprising that mutations in ECM genes have pathological implications, including in muscle, where they can lead to myopathies. However, the particular role of certain disease-related ECM proteins in stem cell maintenance highlights the potential contribution of stem cell deregulation to the progression of these disorders.

Long-Term Effects of Adipose-Derived Stem Cells for the Treatment of Bilateral Limbal Stem Cell Deficiency

Purpose To determine the safety and feasibility of human autologous adipose tissue-derived adult mesenchymal stem cells (ASCs) for ocular surface regeneration in patients with bilateral limbal stem-cell deficiency (LSCD). Methods A phase IIa clinical trial was designed (https://Clinicaltrials.gov, NCT01808378) with 8 patients, 3 of whom had aniridia, 2 meibomian glands diseases, 2 multiple surgeries and 1 chronic chemical injury. The therapeutic protocol was as follows: 6-mm of central corneal epithelium was removed, 400,000 ASCs were injected into each limboconjunctival quadrant, 400,000 ASCs were suspended over the cornea for 20 min, and finally the cornea was covered with an amniotic membrane patch. Results No adverse events were detected after a mean of 86,5 months of follow-up. One year after surgery, 6 of the 8 transplants were scored as successful, five patients had improved uncorrected visual acuity (mean of 12 letters), two patients presented epithelial defects (also present at baseline) and the mean percentage of corneal neovascularization was of 28.75% (36.98%, at baseline). Re-examination 24 months after treatment disclosed preserved efficacy in 4 patients. At the last visit (after a mean of 86,5 months of follow up) epithelial defects were absent in all patients although improvement in all of the variables was only maintained in patient 3 (meibomian glands agenesia). Conclusion ASCs are a feasible and conservative therapy for treating bilateral LSCD. The therapeutic effect differs between etiologies and diminishes over time.

Engineered neurogenesis in naïve adult rat cortex by Ngn2-mediated neuronal reprogramming of resident oligodendrocyte progenitor cells.

Adult tissue stem cells contribute to tissue homeostasis and repair but the long-lived neurons in the human adult cerebral cortex are not replaced, despite evidence for a limited regenerative response. However, the adult cortex contains a population of proliferating oligodendrocyte progenitor cells (OPCs). We examined the capacity of rat cortical OPCs to be re-specified to a neuronal lineage both in vitro and in vivo. Expressing the developmental transcription factor Neurogenin2 (Ngn2) in OPCs isolated from adult rat cortex resulted in their expression of early neuronal lineage markers and genes while downregulating expression of OPC markers and genes. Ngn2 induced progression through a neuronal lineage to express mature neuronal markers and functional activity as glutamatergic neurons. In vivo retroviral gene delivery of Ngn2 to naive adult rat cortex ensured restricted targeting to proliferating OPCs. Ngn2 expression in OPCs resulted in their lineage re-specification and transition through an immature neuronal morphology into mature pyramidal cortical neurons with spiny dendrites, axons, synaptic contacts, and subtype specification matching local cytoarchitecture. Lineage re-specification of rat cortical OPCs occurred without prior injury, demonstrating these glial progenitor cells need not be put into a reactive state to achieve lineage reprogramming. These results show it may be feasible to precisely engineer additional neurons directly in adult cerebral cortex for experimental study or potentially for therapeutic use to modify dysfunctional or damaged circuitry.

Major considerations of the biological mechanisms of bone regeneration through mesenchymal stem cells, exosomes, and microRNAs in the scenario of bucco-maxillo-facial surgery: a systematic review

Introduction: In the context of bucco-maxillo facial surgery, the development of biomaterials for use in clinical dentistry in recent years has represented a powerful therapeutic instrument in the correction of bone defects. Adult tissue stem cells (mesenchymal stem cells) mediate homeostasis and regeneration of tissues and organs. Growing evidence suggests that metabolism during quiescence, activation, and differentiation may vary between tissues, integrating signaling cues and metabolic inputs with the release of exosomes and microRNAs as important metabolic messengers. Objective: It was to carry out a systematic review to present the main considerations and scientific evidence of the cellular and molecular mechanisms of bone formation or regeneration through mesenchymal stem cells, exosomes, and microRNAs in the scenario of bucco-maxillo-facial surgery with bone graft or biomaterials. Methods: The systematic review rules of the PRISMA Platform were followed. The search was carried out from March to May 2023 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases, with articles dated 2001 (gold standard) through 2022. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed accordingly, according to the Cochrane instrument. Results and Conclusion: A total of 145 articles were found, 45 articles were evaluated and 34 were included and developed in this systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 30 studies with a high risk of bias and 15 studies that did not meet GRADE. The greater potential of guided bone regeneration was associated with the graft material due to the higher grade of vital bone and the lower percentage of residual graft particles. Inorganic bovine bone and porcine bone minerals combined with autogenous maxillary cortical bone showed similar biological and radiological characteristics in terms of biomaterial resorption, osteoconduction, and osteogenesis when used for maxillary sinus floor augmentation. In this regard, three fundamental parameters in bone tissue engineering that determine the capacity for osteoinduction were evidenced, such as the presence of soluble osteoinductive signals, the viability of undifferentiated mesenchymal stem cells, having the ability to differentiate into bone-forming cells and production of adequate extracellular matrix. The exosomes that contain proteins, mRNAs, microRNAs, and DNAs stand out. Exosomes change the biochemical characteristics of recipient cells through the delivery of biomolecules and play a role in cell communication. Evidence suggests that exosomes derived from mesenchymal stem cells exhibit functions similar to mesenchymal stem cells with low immunogenicity and without tumorization.

559 Induction of tissue-specific premature stem cell aging promotes senescence-like phenotypes in remote multiple organs

Adult tissue stem cells (SCs) play an important role in tissue homeostasis and regeneration in multicellular organisms. With aging, these cells decline in their capacities such as regeneration, proliferation, and differentiation, leading to disruption of tissue homeostasis in systemic organs. The senescence-associated secretory phenotype (SASP), that is, senescent cells secrete various inflammatory factors, has been implicated in the promotion of chronic inflammation and organismal aging. However, little is known about the common molecular mechanisms underlying SC aging and their influence on systemic aging.

Successful Ex Vivo Telomere Elongation with Exg-001 in a Patient with a Dyskeratosis Congenita

We report a first-in-human gene therapy strategy to extend telomere length in patients with telomere biology disorders. Patients with telomere biology disorders, including dyskeratosis congenita, have extremely short telomeres leading to premature cellular senescence and increased risk of bone marrow failure. Zinc Finger and SCAN Domain Containing 4 (ZSCAN4) is a protein that regulates telomere elongation, enhances genome stability, and is expressed transiently in preimplantation embryos, germ cells during meiosis, embryonic stem cells, and rare adult tissue stem cells. EXG-001 is a non-integrating temperature-sensitive non-transmissible Sendai virus vector encoding for human ZSCAN4. We demonstrated that the transient exposure to ZSCAN4 via EXG-001 extended telomeres of primary fibroblast cells derived from dyskeratosis congenita patients as well as healthy human CD34+ cells. However, we did not know whether EXG-001 can extend short telomeres of CD34+ cells of dyskeratosis congenita patients. We translated this work in a first-in-human clinical trial (NCT04211714), in which autologous CD34+ hematopoietic stem cells (HSC) were collected by pheresis from an adult subject with dyskeratosis congenita over two days after mobilization with plerixafor and filgrastim with IRB approval and consent. 2.8x106 CD34/kg were collected and treated with EXG-001 ex vivo in a functionally closed tubing system using the CliniMACS Prodigy (Miltenyi Biotec). EXG-001 treatment increased telomere length of the CD34+ cells of study subject by 1.24-fold, bringing them into the healthy normal control range of CD34+ cell telomere length (Figure 1A). To address the concern of effects on terminal colony forming unit studies were performed and demonstrated maintenance of normal differentiation potential after treatment (Figure 1B; EXG34217). 0.85x106 CD34/kg autologous treated HSC (EXG34217) were reinfused into the subject in February 2022 without conditioning regimen and further in vivo studies are in progress. This novel approach is genotype and mutation independent and uses modified autologous stem cells in the absence of conditioning regimen or immunosuppression which is highly desirable in this radiation and chemotherapy sensitive population. These data support further investigation and translation of telomere elongation via ZSCAN4 exposure by EXG-001 in patients with telomere biology disorders as a potential therapeutic intervention for the prevention or treatment of bone marrow failure. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The transcription factor LEF1 interacts with NFIX and switches isoforms during adult hippocampal neural stem cell quiescence.

Stem cells in adult mammalian tissues are held in a reversible resting state, known as quiescence, for prolonged periods of time. Recent studies have greatly increased our understanding of the epigenetic and transcriptional landscapes that underlie stem cell quiescence. However, the transcription factor code that actively maintains the quiescence program remains poorly defined. Similarly, alternative splicing events affecting transcription factors in stem cell quiescence have been overlooked. Here we show that the transcription factor T-cell factor/lymphoid enhancer factor LEF1, a central player in canonical β-catenin-dependent Wnt signalling, undergoes alternative splicing and switches isoforms in quiescent neural stem cells. We found that active β-catenin and its partner LEF1 accumulated in quiescent hippocampal neural stem and progenitor cell (Q-NSPC) cultures. Accordingly, Q-NSPCs showed enhanced TCF/LEF1-driven transcription and a basal Wnt activity that conferred a functional advantage to the cultured cells in a Wnt-dependent assay. At a mechanistic level, we found a fine regulation of Lef1 gene expression. The coordinate upregulation of Lef1 transcription and retention of alternative spliced exon 6 (E6) led to the accumulation of a full-length protein isoform (LEF1-FL) that displayed increased stability in the quiescent state. Prospectively isolated GLAST + cells from the postnatal hippocampus also underwent E6 retention at the time quiescence is established in vivo. Interestingly, LEF1 motif was enriched in quiescence-associated enhancers of genes upregulated in Q-NSPCs and quiescence-related NFIX transcription factor motifs flanked the LEF1 binding sites. We further show that LEF1 interacts with NFIX and identify putative LEF1/NFIX targets. Together, our results uncover an unexpected role for LEF1 in gene regulation in quiescent NSPCs, and highlight alternative splicing as a post-transcriptional regulatory mechanism in the transition from stem cell activation to quiescence.

P-112 Oleic acid promotes the malignant transformation of Kras-mutant colonic organoids via the expansion of tumorigenic stem cells and abnormal Paneth cells through upregulation of NFATc family

Although the five-year survival rate of colorectal cancer (CRC) is significantly high with localized stage (90%), only 38% of the patients are diagnosed at this stage. Therefore, finding high risk factors of CRC could prevent the disease at the early stage. Obesity and high-fat diet consumption are risk factors of CRC. In detail, oleic acids (OA) were found to accumulate in the adipose tissues of obese patients as well as being the most common long chain fatty acid in dietary lipid. The role of OA in colorectal cancer development is still controversary. On the other hand, organoids, which can be derived from adult tissue stem cells, are the miniatures of organs. Recent works suggest organoids are useful tools to dissect mechanisms involved in cancer development. The current work aims to utilize crypt stem cell-derived organoids to dissect how obesity can contribute to CRC development. Organoids were derived from Lgr5 + -EGFP mice (normal colon control), Lgr5 + -EGFP-creER; LSL-KrasG12D mice (colonic epithelium harbored KrasG12D mutation) and AOM/DSS-induced CRC mice (cancerous colon control). For in-vitro, the impact of OA on the malignant transformation of Kras-mutant colonic organoids was assessed by MTT proliferation assay, 2D transwell migration and invasion assay, irinotecan-resistant test and colony formation assay. The tumor formation in-vivo was induced by subcutaneous engrafting of OA-treated organoids on NOD/SCID mice. RNAseq was done to screen some differential expressed genes when treating OA. The existence of stem cell and abnormal Paneth cell population was demonstrated by immunostaining, flow cytometry and ELISA. OA enhanced the malignant of Kras-mutant colonic organoids through increasing proliferation, migration, invasion, drug resistance and colony formation. Besides, mice which were engrafted with OA-trained Lgr5-Kras organoids possessed larger tumors. The colonic stem cell population which were represented by positive Lgr5-GFP + cells were upregulated in OA-treated group. Interestingly, there is an existence of abnormal Lyz + /CD24 + Paneth cells in OA-treated Kras-mutant organoids. This suggested that OA may promote abnormal differentiation of colonic progenitor cells. Indeed, treatment of OA upregulated ATOH1 and GFI1, which contributed to select between goblet/Paneth and enteroendocrine cell fates. Besides, NFAT family, among which NFATc3 expressed the most, significantly increased in OA-treated organoids. The upregulation of NFATc was induced by inhibition of proteasomal degradation resulting from low expression of the complex RNF123, USP18 and TRIM30A. In addition, inhibition of the nuclear translocalization of NFATc family by VIVIT demonstrated the decline of stemness markers as well as Paneth cell markers. Finally, we showed the role of NFATc, especially NFATc3, in promoting the malignancy of OA-treated Kras-mutant organoids. Our findings suggested the impact of oleic acid on promoting the malignant transformation of Kras-mutant colonic organoids through NFATc-relating pathway. The expansion of tumorigenic stem cells via induction of abnormal Paneth cell, may contribute to the potential of cancer-toward metaplasia in Kras-mutant organoids when exposing to high level of oleic acid. Oleic acid is an unfavorable factor of colorectal cancer. The frequent usage of OA, which may benefit to cardiovascular diseases, may lead to the increased risk of CRC in latent sensitive Kras-mutant individuals.

GFP Tagged VSELs Help Delineate Novel Stem Cells Biology in Multiple Adult Tissues.

Various types of stem cells are being researched upon to exploit their potential for regenerative medicine including pluripotent human embryonic stem (hES) cells derived from spare human embryos, induced pluripotent stem (iPS) cells by reprogramming somatic cells to a pluripotent state and multipotent mesenchymal stem/stromal cells (MSCs) obtained in vitro from multiple tissues. More than 50 independent groups have reported another novel population of pluripotent stem cells in adult tissues termed very small embryonic-like stem cells (VSELs). VSELs are developmentally linked to primordial germ cells, which rather than giving rise to the germ cells and later ceasing to exist, survive throughout life in multiple organs along with tissue-specific adult stem cells better described as lineage-restricted, tissue-committed progenitors with limited plasticity. VSELs survive total body irradiation in bone marrow, oncotherapy in the gonads, bilateral ovariectomy in the uterus and partial pancreatectomy in the pancreas of mice and participate in the regeneration of multiple organs under normal physiological conditions. VSELs and tissue-specific progenitor cells work together in a subtle manner, maintain life-long tissue homeostasis and their dysfunction leads to various pathologies including cancer. However, due to their quiescent state, VSELs have invariably eluded lineage-tracing studies reported so far. Present article reviews novel insights into VSELs biology and how VSELs enriched from GFP (green fluorescent protein) mice have enabled to delineate their role in various biological processes in vivo. VSELs biology needs to be understood in-depth as this alone will help evolve the field of regenerative medicine and win the war against cancer.

Lineage Tracing of Inducible Fluorescently-Labeled Stem Cells in the Adult Mouse Brain.

A telomerase reverse transcriptase (Tert) lineage-tracing mouse line was developed to investigate the behavior and fate of adult tissue stem cells, by crossing the 'Tet-On' system oTet-Cre mouse with a novel reverse tetracycline transactivator (rtTA) transgene linked to the Tert promoter, which we have demonstrated marks a novel population of adult brain stem cells. Here, administration of the tetracycline derivative doxycycline to mTert-rtTA::oTet-Cre mice will indelibly mark a population of cells that express a 4.4 kb fragment of the promoter region of the gene Tert. When combined the Rosa-mTmG reporter, mTert-rtTA::oTet-Cre::Rosa-mTmG mice will express membrane tdTomato (mTomato) until doxycycline treatment induces the replacement of mTomato expression with membrane EGFP (mGFP) in cells that also express Tert. Therefore, when these triple-transgenic lineage tracing mice receive doxycycline (the "pulse" period during which TERT expressing cells are marked), these cells will become indelibly marked mGFP+ cells, which can be tracked for any desirable amount of time after doxycycline removal (the "chase" period), even if Tert expression is subsequently lost. Brains are then perfusion-fixed and processed for immunofluorescence and other downstream applications in order to interpret changes to stem cell activation, proliferation, lineage commitment, migration to various brain niches, and differentiation to mature cell types. Using this system, any rtTA mouse can be mated to oTet-Cre and a Rosa reporter to conduct doxycycline-inducible "pulse-chase" lineagetracing experiments using markers of stem cells.

Improvement of an Effective Protocol for Directed Differentiation of Human Adipose Tissue-Derived Adult Mesenchymal Stem Cells to Corneal Endothelial Cells.

Corneal disease affects 12.5 million individuals worldwide, with 2 million new cases each year. The standard treatment consists of a corneal transplantation from a human donor; however, the worldwide demand significantly exceeds the available supply. Lamellar endothelial keratoplasty, the replacement of only the endothelial layer of the cornea, can partially solve the problem. Progressive efforts have succeeded in expanding hCECs; however, the ability to expand hCECs is still limited, and new sources of CECs are being sought. Crucial advances have been achieved by the directed differentiation of embryonic or induced pluripotent stem cells, but these cells have disadvantages, such as the use of oncogenes, and are still difficult to establish. We aimed to transfer such knowledge to obtain hCECs from adipose tissue-derived adult mesenchymal stem cells (ADSC) by modifying four previously published procedures. We present several protocols capable of the directed differentiation of human ADSCs to hCECs. In our hands, the protocol by Ali et al. was the best adapted to such differentiation in terms of efficiency, time, and financial cost; however, the protocol by Wagoner et al. was the best for CEC marker expression. Our results broaden the type of cells of autologous extraocular origin that could be employed in the clinical setting for corneal endothelial deficiency.

Gvhd Targets Organoid-Forming Biliary Epithelial Stem Cells Via a TGF-β-Dependent Manner

[Introduction] Graft-versus-host disease (GVHD) is a potentially life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). We and others have shown that GVHD targets adult tissue stem cells in the gut and skin, while a role of liver tissue stem cells in hepatic GVHD remains to be clarified. Biliary epithelial cells (BECs) are primary targets in hepatic GVHD and a single BEC stem cell gives rise to multipotent liver organoids (Cao W: Gastroenterology 2017). We studied the fate and role of BEC stem cells in experimental hepatic GVHD. [Methods] B6D2F1 recipients were lethally irradiated and transplanted with 5 x 10 6 splenocytes plus 5 x 10 6 bone marrow cells from allogeneic (B6) or syngeneic (B6D2F1) donors on day 0. Liver organoids were generated from the bile ducts isolated from the liver right lobe. [Results] Flowcytometric analyses of the liver demonstrated donor T cell infiltration in the liver within the first week after allo-HCT, followed by massive infiltration of monocytes and macrophages. Hepatic GVHD was characterized by apoptosis of BEC (Figure 1A), elevated expression of Mmp7, a biomarker of biliary injury (Figure 1B), and elevation of plasma levels of total bilirubin (Figure 1C). To evaluate fate of BEC stem cells in hepatic GVHD, we enumerated BEC-derived organoids generated from the right lobe of the liver isolated after allo-HCT. The organoid-forming BEC stem cells were profoundly reduced at later time point after allo-HCT (Figure 1D), while they persisted in syngeneic controls, indicating that GVHD targets BEC stem cells. Next, we explored the mechanism of BEC stem cell injury. Among the cytokines elevated in the liver after allo-HCT, we found that TGF-β, not IFN-γ or TNF-α, inhibited generation of liver organoids (Figure 1E). Furthermore, we found that liver infiltrating mononuclear cells isolated from the allogeneic livers, not from syngeneic livers, suppressed growth of liver organoids. This effect was abrogated by the addition of a TGF-β inhibitor, SB-431542 in culture. Among these cells, monocyte-derived macrophages, not Kupffer cells, demonstrated enhanced production of TGF-β after allo-HCT (Figure 1F), suggesting that TGF-β from inflammatory macrophages damaged BEC stem cells. Based on these findings, we next tested if TGF-β inhibition could protect BEC stem cells and ameliorate hepatic GVHD after allo-HCT. Admnistration of SB-431542 from day +14 to day +28 after allo-HCT significantly increased organoid-forming BEC stem cells, suppressed BEC apoptosis and Mmp7 expression, and mitigated jaundice on day +28 after allogeneic HCT, indicating that TGF-β inhibition is a novel therapeutic strategy against hepatic GVHD (Figure 1, G-J). [Conclusion] Our results for the first time demonstrated that hepatic GVHD targets BEC stem cells via a TGF-β-dependent manner. Mmp7 and organoid-forming capacity could be the biomarkers for hepatic GVHD. BEC stem-cell protection by TGF-β inhibition is a promising novel therapeutic strategy against hepatic GVHD.Figures1: (A) Proportion of cleaved caspase 3 (cCaspase3) + cells among the biliary epithelial cells (BECs) on day +28. (B) Total RNA extracted from the liver on day +28 was subjected to Q-PCR targeting Mmp7. (C) Plasma levels of total bilirubin at indicated time points. (D) The numbers of organoid derived from the right lobe of the liver at indicated time point are shown. (E) Absolute numbers of TGF-β producing Kupffer cells and macrophages (Mφ) in the liver on day +28 are shown. (F) Liver organoids were enumerated after incubation in the presence or absence of TGF-β for 4 days. (G-J) Allogeneic recipients were intraperitoneally injected with 5 mg/kg SB-431542 daily from day +14 to day +28 after allogeneic HCT, and recipient mice were sacrificed on day +28. Numbers of organoids derived from the right lobe of the livers (G), the proportion of cCaspase3 + BECs (H), relative expression of Mmp7 in the liver (I), and plasma levels of total bilirubin (J) are shown. *; p < .05, **; p < .01, ***; p < .005. [Display omitted] DisclosuresTeshima: CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; Takeda Pharmaceutical Company: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis International AG: Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Gentium/Jazz Pharmaceuticals: Consultancy; Bristol Myers Squibb: Honoraria; Sanofi S.A.: Research Funding; TEIJIN PHARMA Limited: Research Funding; Nippon Shinyaku Co., Ltd.: Research Funding; Fuji pharma CO.,Ltd: Research Funding; Pfizer Inc.: Honoraria; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin Co.,Ltd.: Honoraria, Research Funding; Astellas Pharma Inc.: Research Funding; Janssen Pharmaceutical K.K.: Other.

Human Organoids for Predictive Toxicology Research and Drug Development.

Organoids are three-dimensional structures fabricated in vitro from pluripotent stem cells or adult tissue stem cells via a process of self-organization that results in the formation of organ-specific cell types. Human organoids are expected to mimic complex microenvironments and many of the in vivo physiological functions of relevant tissues, thus filling the translational gap between animals and humans and increasing our understanding of the mechanisms underlying disease and developmental processes. In the last decade, organoid research has attracted increasing attention in areas such as disease modeling, drug development, regenerative medicine, toxicology research, and personalized medicine. In particular, in the field of toxicology, where there are various traditional models, human organoids are expected to blaze a new path in future research by overcoming the current limitations, such as those related to differences in drug responses among species. Here, we discuss the potential usefulness, limitations, and future prospects of human liver, heart, kidney, gut, and brain organoids from the viewpoints of predictive toxicology research and drug development, providing cutting edge information on their fabrication methods and functional characteristics.

Challenges in Studying Stem Cell Metabolism.

The expanding field of stem cell metabolism has been supported by technical advances in metabolite profiling and novel functional analyses. While use of these methodologies has been fruitful, many challenges are posed by the intricacies of culturing stem cells invitro, along with the distinctive scarcity of adult tissue stem cells and the complexities of their niches invivo. This review provides an examination of the methodologies used to characterize stem cell metabolism, highlighting their utility while placing a sharper focus on their limitations and hurdles the field needs to overcome for the optimal study of stem cell metabolic networks.

Revealing Tissue-Specific SARS-CoV-2 Infection and Host Responses using Human Stem Cell-Derived Lung and Cerebral Organoids.

SummaryCOVID-19 is a transmissible respiratory disease caused by a novel coronavirus, SARS-CoV-2, and has become a global health emergency. There is an urgent need for robust and practical in vitro model systems to investigate viral pathogenesis. Here, we generated human induced pluripotent stem cell (iPSC)-derived lung organoids (LORGs), cerebral organoids (CORGs), neural progenitor cells (NPCs), neurons, and astrocytes. LORGs containing epithelial cells, alveolar types 1 and 2, highly express ACE2 and TMPRSS2 and are permissive to SARS-CoV-2 infection. SARS-CoV-2 infection induces interferons, cytokines, and chemokines and activates critical inflammasome pathway genes. Spike protein inhibitor, EK1 peptide, and TMPRSS2 inhibitors (camostat/nafamostat) block viral entry in LORGs. Conversely, CORGs, NPCs, astrocytes, and neurons express low levels of ACE2 and TMPRSS2 and correspondingly are not highly permissive to SARS-CoV-2 infection. Infection in neuronal cells activates TLR3/7, OAS2, complement system, and apoptotic genes. These findings will aid in understanding COVID-19 pathogenesis and facilitate drug discovery.

Prospects for 3D bioprinting of organoids

Three-dimensional (3D) organoids derived from pluripotent or adult tissue stem cells seem to possess excellent potential for studying development and disease mechanisms alongside having a myriad of applications in regenerative therapies. However, lack of precise architectures and large-scale tissue sizes are some of the key limitations of current organoid technologies. 3D bioprinting of organoids has recently emerged to address some of these impediments. In this review, we discuss 3D bioprinting with respect to the use of bioinks and bioprinting methods and highlight recent studies that have shown success in bioprinting of stem cells and organoids. We also summarize the use of several vascularization strategies for the bioprinted organoids, that are critical for a complex tissue organization. To fully realize the translational applications of organoids in disease modeling and regenerative medicine, these areas in 3D bioprinting need to be appropriately harnessed and channelized.

Comparison of three sperm selection methods for ICSI-DGC, Cumulus column, and incubation with supernatant product of adipose tissue-derived adult stem cells: An experimental study.

BackgroundThe examination of sperm parameters and sperm DNA integrity are necessary for male fertility expression. These parameters can be affected by method of sperm separation.ObjectiveTo measure the damage of each sperm separation method on the sperm parameters and sperm DNA integrity.Materials and MethodsIn this experimental study, semen samples of 20 infertile men with asthenoteratozoospermia (Infertility Research Center, Qom, Iran, 2017) were processed in three ways: density gradient centrifugation (DGC), cumulus column, and incubation with supernatant products of adipose tissue-derived adult stem cells (SPAS). The results of sperm parameters and DNA fragmentation before and after the process were statistically analyzed.ResultsThe number of separated sperms by normal morphologies during the SPAS and the cumulus column was significantly more than the corresponding population in the DGC group. In addition, although all three methods have the same ability to increase total sperm motility and the number of recovered sperms, in the field of forwarding movement and DNA fragmentation, the SPAS method performed more efficiently (p = 0.021).ConclusionSperm parameters and DNA fragmentation in the SPAS group were better than those in the DGC and cumulus column groups. Furthermore, it has been shown that the sperm capacity was increased with the SPAS method. However, the rearrangement of sperm chromatin by reducing the disulfide bridges and providing the possibility of re-histone over capacity causes a significant reduction in DNA fragmentation.

Epigenetic Signatures and Plasticity of Intestinal and Other Stem Cells.

The cardinal properties of adult tissue stem cells are self-renewal and the ability to generate diverse resident cell types. The daily losses of terminally differentiated intestinal, skin, and blood cells require "professional" stem cells to produce replacements. This occurs by continuous expansion of stem cells and their immediate progeny, followed by coordinated activation of divergent transcriptional programs to generate stable cells with diverse functions. Other tissues turn over slowly, if at all, and vary widely in strategies for facultative stem cell activity or interconversion among mature resident cell types (transdifferentiation). Cell fate potential is programmed in tissue-specific configurations of chromatin, which restrict the complement of available genes and cis-regulatory elements, hence allowing specific cell types to arise. Using as a model the transcriptional and chromatin basis of cell differentiation and dedifferentiation in intestinal crypts, we discuss here how self-renewing and other tissues execute homeostatic and injury-responsive stem cell activity.