Source Of Progenitors Research Articles

FRB 20121102A monitoring: Updated periodicity in the L band

FRB 20121102A was the first fast radio burst to be observed to repeat. Since then, thousands of bursts have been detected by multiple radio telescopes around the world. Previous work has shown an indication of a cyclic activity level with a periodicity of around 160 days. Knowing when the source repeats is essential for planning multi-wavelength monitoring to constrain the emission extent and progenitor source. We report the monitoring of FRB 20121102A using the 100-m Effelsberg radio telescope in the L band and update the periodicity of the cyclic activity level. We used the Lomb-Scargle periodogram on a sample of 284 observing epochs, of which percent correspond to detections and percent to non-detections. Our dataset is composed of the seven epochs of our monitoring plus publicly available data. We investigated two methods: i) a binary model, describing the observing epochs with if there are detections and with 0 for non-detections, and ii) a normalised rates model that considers the inferred detection rates. We report no detections in 12.5-hour observations down to a fluence of s . The best period we find for the cyclic activity window is days for the binary model and days for the normalised rates model. We show the activity phase to be percent . The normalised rates show clear Gaussian-like behaviour for the activity level, in that the number of detections peaks at the centre of the activity window. The periodicity found through both methods is consistent for the L- and S-band datasets, implying it is intrinsic to the source. The activity phase in the S band however, shows an indication of it ending before the L-band activity phase, supporting the idea of a chromatic dependence of the activity window. The sample in the C band is not large enough to further confirm this result.

Prolonged cultivation enhances the stimulatory activity of hiPSC mesenchymal progenitor-derived conditioned medium

BackgroundHuman induced pluripotent stem cells represent a scalable source of youthful tissue progenitors and secretomes for regenerative therapies. The aim of our study was to investigate the potential of conditioned medium (CM) from hiPSC-mesenchymal progenitors (hiPSC-MPs) to stimulate osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (MSCs). We also investigated whether prolonged cultivation or osteogenic pre-differentiation of hiPSC-MPs could enhance the stimulatory activity of CM.MethodsMSCs were isolated from 13 donors (age 20–90 years). CM derived from hiPSC-MPs was added to the MSC cultures and the effects on proliferation and osteogenic differentiation were examined after 14 days and 6 weeks. The stimulatory activity of hiPSC-MP-CM was compared with the activity of MSC-derived CM and with the activity of CM prepared from hiPSC-MPs pre-cultured in growth or osteogenic medium for 14 days. Comparative proteomic analysis of CM was performed to gain insight into the molecular components responsible for the stimulatory activity.ResultsPrimary bone marrow-derived MSC exhibited variability, with a tendency towards lower proliferation and tri-lineage differentiation in older donors. hiPSC-MP-CM increased the proliferation and alkaline phosphatase activity of MSC from several adult/aged donors after 14 days of continuous supplementation under osteogenic conditions. However, CM supplementation failed to improve the mineralization of MSC pellets after 6 weeks under osteogenic conditions. hiPSC-MP-CM showed greater enhancement of proliferation and ALP activity than CM derived from bone marrow-derived MSCs. Moreover, 14-day cultivation but not osteogenic pre-differentiation of hiPSC-MPs strongly enhanced CM stimulatory activity. Quantitative proteomic analysis of d14-CM revealed a distinct profile of components that formed a highly interconnected associations network with two clusters, one functionally associated with binding and organization of actin/cytoskeletal components and the other with structural constituents of the extracellular matrix, collagen, and growth factor binding. Several hub proteins were identified that were reported to have functions in cell-extracellular matrix interaction, osteogenic differentiation and development.ConclusionsOur data show that hiPSC-MP-CM enhances early osteogenic differentiation of human bone marrow-derived MSCs and that prolonged cultivation of hiPSC-MPs enhances CM-stimulatory activity. Proteomic analysis of the upregulated protein components provides the basis for further optimization of hiPSC-MP-CM for bone regenerative therapies.Graphical

Extracellular vesicles from II trimester human amniotic fluid as paracrine conveyors counteracting oxidative stress

BackgroundWe previously demonstrated that the human amniotic fluid (hAF) from II trimester of gestation is a feasible source of stromal progenitors (human amniotic fluid stem cells, hAFSC), with significant paracrine potential for regenerative medicine. Extracellular vesicles (EVs) separated and concentrated from hAFSC secretome can deliver pro-survival, proliferative, anti-fibrotic and cardioprotective effects in preclinical models of skeletal and cardiac muscle injury. While hAFSC-EVs isolation can be significantly influenced by in vitro cell culture, here we profiled EVs directly concentrated from hAF as an alternative option and investigated their paracrine potential against oxidative stress. MethodsII trimester hAF samples were obtained as leftover material from prenatal diagnostic amniocentesis following written informed consent. EVs were separated by size exclusion chromatography and concentrated by ultracentrifugation. hAF-EVs were assessed by nanoparticle tracking analysis, transmission electron microscopy, Western Blot, and flow cytometry; their metabolic activity was evaluated by oximetric and luminometric analyses and their cargo profiled by proteomics and RNA sequencing. hAF-EV paracrine potential was tested in preclinical in vitro models of oxidative stress and dysfunction on murine C2C12 cells and on 3D human cardiac microtissue. ResultsOur protocol resulted in a yield of 6.31 ± 0.98 × 109 EVs particles per hAF milliliter showing round cup-shaped morphology and 209.63 ± 6.10 nm average size, with relevant expression of CD81, CD63 and CD9 tetraspanin markers. hAF-EVs were enriched in CD133/1, CD326, CD24, CD29, and SSEA4 and able to produce ATP by oxygen consumption. While oxidative stress significantly reduced C2C12 survival, hAF-EV priming resulted in significant rescue of cell viability, with notable recovery of ATP synthesis and concomitant reduction of cell damage and lipid peroxidation activity. 3D human cardiac microtissues treated with hAF-EVs and experiencing H2O2 stress and TGFβ stimulation showed improved survival with a remarkable decrease in the onset of fibrosis. ConclusionsOur results suggest that leftover samples of II trimester human amniotic fluid can represent a feasible source of EVs to counteract oxidative damage on target cells, thus offering a novel candidate therapeutic option to counteract skeletal and cardiac muscle injury.

Bayesian real-time classification of multi-messenger electromagnetic and gravitational-wave observations

Because of the electromagnetic (EM) radiation produced during the merger, compact binary coalescences with neutron stars may result in multi-messenger observations. In order to follow up on the gravitational-wave (GW) signal with EM telescopes, it is critical to promptly identify the properties of these sources. This identification must rely on the properties of the progenitor source, such as the component masses and spins, as determined by low-latency detection pipelines in real time. The output of these pipelines, however, might be biased, which could decrease the accuracy of parameter recovery. Machine learning algorithms are used to correct this bias. In this work, we revisit this problem and discuss two new implementations of supervised machine learning algorithms, K-nearest neighbors and random forest, which are able to predict the presence of a neutron star and post-merger matter remnant in low-latency compact binary coalescence searches across different search pipelines and data sets. Additionally, we present a novel approach for calculating the Bayesian probabilities for these two metrics. Instead of metric scores derived from binary machine learning classifiers, our scheme is designed to provide the astronomy community well-defined probabilities. This would deliver a more direct and easily interpretable product to assist EM telescopes in deciding whether to follow up on GW events in real time.

Enteric glial cell diversification is influenced by spatiotemporal factors and source of neural progenitors in mice.

Previously focused primarily on enteric neurons, studies of the enteric nervous system (ENS) in both health and disease are now broadening to recognize the equally significant role played by enteric glial cells (EGCs). Commensurate to the vast array of gastrointestinal functions they influence, EGCs exhibit considerable diversity in terms of location, morphology, molecular profiles, and functional attributes. However, the mechanisms underlying this diversification of EGCs remain largely unexplored. To begin unraveling the mechanistic complexities of EGC diversity, the current study aimed to examine its spatiotemporal aspects in greater detail, and to assess whether the various sources of enteric neural progenitors contribute differentially to this diversity. Based on established topo-morphological criteria for categorizing EGCs into four main subtypes, our detailed immunofluorescence analyses first revealed that these subtypes emerge sequentially during early postnatal development, in a coordinated manner with the structural changes that occur in the ENS. When combined with genetic cell lineage tracing experiments, our analyses then uncovered a strongly biased contribution by Schwann cell-derived enteric neural progenitors to particular topo-morphological subtypes of EGCs. Taken together, these findings provide a robust foundation for further investigations into the molecular and cellular mechanisms governing EGC diversity.

Adipose-derived mesenchymal stem cells (MSCs) are a superior cell source for bone tissue engineering

Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors, osteoinductive biofactors and biocompatible scaffold materials. Mesenchymal stem cells (MSCs) represent the most promising seed cells for bone tissue engineering. As multipotent stem cells that can self-renew and differentiate into multiple lineages including bone and fat, MSCs can be isolated from numerous tissues and exhibit varied differentiation potential. To identify an optimal progenitor cell source for bone tissue engineering, we analyzed the proliferative activity and osteogenic potential of four commonly-used mouse MSC sources, including immortalized mouse embryonic fibroblasts (iMEF), immortalized mouse bone marrow stromal stem cells (imBMSC), immortalized mouse calvarial mesenchymal progenitors (iCAL), and immortalized mouse adipose-derived mesenchymal stem cells (iMAD). We found that iMAD exhibited highest osteogenic and adipogenic capabilities upon BMP9 stimulation in vitro, whereas iMAD and iCAL exhibited highest osteogenic capability in BMP9-induced ectopic osteogenesis and critical-sized calvarial defect repair. Transcriptomic analysis revealed that, while each MSC line regulated a distinct set of target genes upon BMP9 stimulation, all MSC lines underwent osteogenic differentiation by regulating osteogenesis-related signaling including Wnt, TGF-β, PI3K/AKT, MAPK, Hippo and JAK-STAT pathways. Collectively, our results demonstrate that adipose-derived MSCs represent optimal progenitor sources for cell-based bone tissue engineering.

Intracerebral Hemorrhage Leads to Anemia By Disrupting Erythropoiesis and Erythromyeloblastic Islands

Intracerebral hemorrhage (ICH), caused by the rupture of a cerebral vessel and subsequent entry of blood into the brain parenchyma, is a major form of acquired brain injury and contributes a remarkable proportion of stroke-related morbidity and mortality. Due to the few proven effective emergency and preventive treatments, patients who survived suffer varying degrees of poor prognosis that affect their quality of life. There is an urgent need to explore the cellular and molecular basis of the differences in the severity and prognosis of ICH. Anemia is a common manifestation of ICH. However, the mechanisms underlying ICH-induced anemia as we as the correlation between anemia and ICH progression/prognosis remain unclear. In this study, we found that approximately 35.1% (39 of 111) of ICH patients exhibited anemia and that decreased hemoglobin levels were positively associated with higher scores on the National Institutes of Health Stroke Scale, which quantifies the degree of neurological deficit, at admission. Furthermore, patients with decreased hemoglobin levels at admission showed higher modified Rankin scale scores at 3 months, which reflect the global disability of daily living at this time, suggesting that anemia was associated with a more severe progression and poor patient prognosis. To investigate the effects of ICH on bone marrow (BM) erythropoiesis, we conducted experiments in 12-month-old mice with collagenase-induced striatal ICH. Our results showed that ICH caused apparent anemia on day 3, associated with larger hematomas in the striatum and more severe neurologic deficits. We first evaluated the phenotype of hematopoietic progenitors and found that mice suffering ICH exhibited increased granulocyte monocyte progenitors but a significant decrease in common myeloid progenitors and megakaryocyte erythrocyte progenitors compared to control mice, suggesting a reduced source of erythroid progenitors. Further analysis revealed that the colony-forming ability of erythroid progenitors and subsequent terminal differentiation was significantly suppressed after ICH. To assess whether ICH-induced suppression of erythropoiesis is associated with erythromyeloblastic islands (EMBIs), the niche for erythropoiesis/myelopoiesis, we performed ICH using 12-month-old EpoR-tdTomato-Cre mice and found that the number of BM EMBIs and EpoR + macrophages decreased significantly. Moreover, the number and proportion of developing erythroid cells surrounding EMBIs decreased while LY6G + cells representing granulocytes increased prominently, indicating an altered microenvironment, with EMBI favoring granulopoiesis over erythropoiesis after ICH. Studies have shown that inflammation plays a crucial role in secondary brain injury after ICH. We hypothesize that inflammatory cytokines may contribute to the suppression of erythropoiesis observed in ICH mouse models. To test this, we measured inflammatory factors in both peripheral blood and BM fluid using Quantibody Mouse Inflammation Array. In particular, IL-6 concentrations in peripheral blood and BM fluid in ICH mice were significantly higher than controls. Treatment with MR16-1, an IL-6 antagonist, alleviated ICH-induced anemia and improved BM erythropoiesis in ICH mice, as evidenced by increased peripheral red blood cells and hemoglobin levels, elevated numbers of erythroid progenitors and terminal erythroblast. MR16-1 treatment also improved BM EMBI formation and increased EpoR + macrophages. In addition, MR16-1 treatment effectively improved neurologic deficits and reduced brain hematoma after ICH. Administration of recombinant IL-6 to wild-type mice resulted in decreased levels of red blood cells and hemoglobin along with suppression of erythropoiesis in the BM. Collectively, these results suggest that ICH modulates erythropoiesis and erythromyeloblastic islands function to ultimately lead to anemia and reveal a possible therapeutic opportunity to reverse ICH-induced anemia and improve ICH prognosis by targeting IL-6.

Intra-articular bone marrow mononuclear cell therapy improves lameness from naturally occurring equine osteoarthritis.

Osteoarthritis (OA) can be debilitating and is related to impaired resolution of synovial inflammation. Current treatments offer temporary relief of clinical signs, but have potentially deleterious side effects. Bone marrow mononuclear cells (BMNC) are a rich source of macrophage progenitors that have the ability to reduce OA symptoms in people and inflammation in experimentally-induced synovitis in horses. The objective of this study was to evaluate the ability of intra-articular BMNC therapy to improve clinical signs of naturally occurring equine OA. Horses presenting with clinical and radiographic evidence of moderate OA in a single joint were randomly assigned to 1 of 3 treatment groups: saline (negative control), triamcinolone (positive control), or BMNC (treatment group). Lameness was evaluated subjectively and objectively, joint circumference measured, and synovial fluid collected for cytology and growth factor/cytokine quantification at 0, 7, and 21 days post-injection. Data were analyzed using General Estimating Equations with significance set at p < 0.05. There were no adverse effects noted in any treatment group. There was a significant increase in synovial fluid total nucleated cell count in the BMNC-treated group on day 7 (median 440; range 20-1920 cells/uL) compared to day 0. Mononuclear cells were the predominant cell type across treatments at all time points. Joint circumference decreased significantly in the BMNC-treated group from days 7 to 21 and was significantly lower at day 21 in the BMNC-treated group compared to the saline-treated group. Median objective lameness improved significantly in the BMNC group between days 7 and 21. GM-CSF, IL-1ra, IGF-1, and TNF-α were below detectable limits and IL-6, IL-1β, FGF-2 were detectable in a limited number of synovial fluid samples. Inconsistent and limited differences were detected over time and between treatment groups for synovial fluid PGE2, SDF-1, MCP-1 and IL-10. Decreased lameness and joint circumference, coupled with a lack of adverse effects following BMNC treatment, support a larger clinical trial using BMNC therapy to treat OA in horses.

A branching model of lineage differentiation underpinning the neurogenic potential of enteric glia

Glial cells have been proposed as a source of neural progenitors, but the mechanisms underpinning the neurogenic potential of adult glia are not known. Using single cell transcriptomic profiling, we show that enteric glial cells represent a cell state attained by autonomic neural crest cells as they transition along a linear differentiation trajectory that allows them to retain neurogenic potential while acquiring mature glial functions. Key neurogenic loci in early enteric nervous system progenitors remain in open chromatin configuration in mature enteric glia, thus facilitating neuronal differentiation under appropriate conditions. Molecular profiling and gene targeting of enteric glial cells in a cell culture model of enteric neurogenesis and a gut injury model demonstrate that neuronal differentiation of glia is driven by transcriptional programs employed in vivo by early progenitors. Our work provides mechanistic insight into the regulatory landscape underpinning the development of intestinal neural circuits and generates a platform for advancing glial cells as therapeutic agents for the treatment of neural deficits.

Scalable Generation of Pre-Vascularized and Functional Human Beige Adipose Organoids.

Obesity and type 2 diabetes are becoming a global sociobiomedical burden. Beige adipocytes are emerging as key inducible actors and putative relevant therapeutic targets for improving metabolic health. However, in vitro models of human beige adipose tissue are currently lacking and hinder research into this cell type and biotherapy development. Unlike traditional bottom-up engineering approaches that aim to generate building blocks, here a scalable system is proposed to generate pre-vascularized and functional human beige adipose tissue organoids using the human stromal vascular fraction of white adipose tissue as a source of adipose and endothelial progenitors. This engineered method uses a defined biomechanical and chemical environment using tumor growth factor β (TGFβ) pathway inhibition and specific gelatin methacryloyl (GelMA) embedding parameters to promote the self-organization of spheroids in GelMA hydrogel, facilitating beige adipogenesis and vascularization. The resulting vascularized organoids display key features of native beige adipose tissue including inducible Uncoupling Protein-1 (UCP1) expression, increased uncoupled mitochondrial respiration, and batokines secretion. The controlled assembly of spheroids allows to translate organoid morphogenesis to a macroscopic scale, generating vascularized centimeter-scale beige adipose micro-tissues. This approach represents a significant advancement in developing in vitro human beige adipose tissue models and facilitates broad applications ranging from basic research to biotherapies.

Understanding Epicardial Cell Heterogeneity during Cardiogenesis and Heart Regeneration.

The outermost layer of the heart, the epicardium, is an essential cell population that contributes, through epithelial-to-mesenchymal transition (EMT), to the formation of different cell types and provides paracrine signals to the developing heart. Despite its quiescent state during adulthood, the adult epicardium reactivates and recapitulates many aspects of embryonic cardiogenesis in response to cardiac injury, thereby supporting cardiac tissue remodeling. Thus, the epicardium has been considered a crucial source of cell progenitors that offers an important contribution to cardiac development and injured hearts. Although several studies have provided evidence regarding cell fate determination in the epicardium, to date, it is unclear whether epicardium-derived cells (EPDCs) come from specific, and predetermined, epicardial cell subpopulations or if they are derived from a common progenitor. In recent years, different approaches have been used to study cell heterogeneity within the epicardial layer using different experimental models. However, the data generated are still insufficient with respect to revealing the complexity of this epithelial layer. In this review, we summarize the previous works documenting the cellular composition, molecular signatures, and diversity within the developing and adult epicardium.

SMAD4: A critical regulator of cardiac neural crest cell fate and vascular smooth muscle development.

During embryogenesis, cardiac neural crest-derived cells (NCs) migrate into the pharyngeal arches and give rise to the vascular smooth muscle cells (vSMCs) of the pharyngeal arch arteries (PAAs). vSMCs are critical for the remodeling of the PAAs into their final adult configuration, giving rise to the aortic arch and its arteries (AAAs). We investigated the role of SMAD4 in NC-to-vSMC differentiation using lineage-specific inducible mouse strains. We found that the expression of SMAD4 in the NC is indelible for regulating the survival of cardiac NCs. Although the ablation of SMAD4 at E9.5 in the NC lineage led to a near-complete absence of NCs in the pharyngeal arches, PAAs became invested with vSMCs derived from a compensatory source. Analysis of AAA development at E16.5 showed that the alternative vSMC source compensated for the lack of NC-derived vSMCs and rescued AAA morphogenesis. Our studies uncovered the requisite role of SMAD4 in the contribution of the NC to the pharyngeal arch mesenchyme. We found that in the absence of SMAD4+ NCs, vSMCs around the PAAs arose from a different progenitor source, rescuing AAA morphogenesis. These findings shed light on the remarkable plasticity of developmental mechanisms governing AAA development.

Engineering of extracellular matrix from human iPSC-mesenchymal progenitors to enhance osteogenic capacity of human bone marrow stromal cells independent of their age.

Regeneration of bone defects is often limited due to compromised bone tissue physiology. Previous studies suggest that engineered extracellular matrices enhance the regenerative capacity of mesenchymal stromal cells. In this study, we used human-induced pluripotent stem cells, a scalable source of young mesenchymal progenitors (hiPSC-MPs), to generate extracellular matrix (iECM) and test its effects on the osteogenic capacity of human bone-marrow mesenchymal stromal cells (BMSCs). iECM was deposited as a layer on cell culture dishes and into three-dimensional (3D) silk-based spongy scaffolds. After decellularization, iECM maintained inherent structural proteins including collagens, fibronectin and laminin, and contained minimal residual DNA. Young adult and aged BMSCs cultured on the iECM layer in osteogenic medium exhibited a significant increase in proliferation, osteogenic marker expression, and mineralization as compared to tissue culture plastic. With BMSCs from aged donors, matrix mineralization was only detected when cultured on iECM, but not on tissue culture plastic. When cultured in 3D iECM/silk scaffolds, BMSCs exhibited significantly increased osteogenic gene expression levels and bone matrix deposition. iECM layer showed a similar enhancement of aged BMSC proliferation, osteogenic gene expression, and mineralization compared with extracellular matrix layers derived from young adult or aged BMSCs. However, iECM increased osteogenic differentiation and decreased adipocyte formation compared with single protein substrates including collagen and fibronectin. Together, our data suggest that the microenvironment comprised of iECM can enhance the osteogenic activity of BMSCs, providing a bioactive and scalable biomaterial strategy for enhancing bone regeneration in patients with delayed or failed bone healing.

Simultaneous Administration of Berberine and Transplantation of Endometrial Stem Cell-Derived Insulin Precursor Cells on a Nanofibrous Scaffold to Treat Diabetes Mellitus in Mice.

Today, significant success has been achieved in treating diabetes with cell therapy derived from various sources of stem and progenitors. The replacement of beta cells is one of the new diabetes treatment methods. To this end, the production of pancreatic beta precursors in cell culture has created an important research field for diabetes treatment. Endometrial stem cells were isolated using an enzymatic method, and after their identity was confirmed using a flow cytometry and differentiation potential assay, the isolated cells were cultured on an electrospun PCL/CS scaffold. Endometrial cells were differentiated into insulin-producing cells (IPCs), and gene expression was analyzed using the qRT-PCR and immunofluorescence to confirm the creation of IPCs. Then, IPCs on the scaffold along with berberine were applied to 5 groups of diabetic mice, and after 6 weeks, insulin, blood glucose, and weight of the animals were measured. The findings revealed that pancreatic markers were significantly expressed in IPCs compared to control cells. In addition, when compared to the control group and scaffolds, the receiving group of IPCs on scaffolds had a significant improvement (p ≤ 0.0015), and this improvement increased with the addition of berberine (decrease in blood sugar (133 mg/dL), and an increase in weight (5/39 g) and insulin (2.29 MIU/L). Thus, tissue engineering is a promising new strategy for treating diabetes and can be used in the future for cell therapy and suitable drugs for diabetic patients.

Simultaneous and panchromatic observations of the fast radio burst FRB 20180916B

Aims.Fast radio bursts are bright radio transients whose origins are not yet understood. The search for a multi-wavelength counterpart of those events can set a tight constraint on the emission mechanism and the progenitor source.Methods.We conducted a multi-wavelength observational campaign on FRB 20180916B between October 2020 and August 2021 over eight activity cycles of the source. Observations were carried out in the radio band by the SRT both at 336 and 1547 MHz and the uGMRT at 400 MHz. Simultaneous observations were conducted by the optical telescopes Asiago (GalileoandCopernico), CMO SAI MSU, CAHA 2.2 m, RTT-150 and TNG, and X/γ-ray detectors on board the AGILE,Insight–HXMT, INTEGRAL, andSwiftsatellites.Results.We present the detection of 14 new radio bursts detected with the SRT at 336 MHz and seven new bursts with the uGMRT from this source. We provide the deepest prompt upper limits in the optical band for FRB 20180916B to date. In fact, the TNG/SiFAP2 observation simultaneous to a burst detection by uGMRT gives an upper limitEoptical/Eradio &lt; 1.3 × 102. Another burst detected by the SRT at 336 MHz was also co-observed byInsight–HXMT. The non-detection in the X-rays yields an upper limit (1 − 30 keV band) ofEX − ray/Eradioin the range of (0.9 − 1.3) × 107, depending on the model that is considered for the X-ray emission.

A single-cell transcriptional atlas reveals resident progenitor cell niche functions in TMJ disc development and injury

The biological characteristics of the temporomandibular joint disc involve complex cellular network in cell identity and extracellular matrix composition to modulate jaw function. The lack of a detailed characterization of the network severely limits the development of targeted therapies for temporomandibular joint-related diseases. Here we profiled single-cell transcriptomes of disc cells from mice at different postnatal stages, finding that the fibroblast population could be divided into chondrogenic and non-chondrogenic clusters. We also find that the resident mural cell population is the source of disc progenitors, characterized by ubiquitously active expression of the NOTCH3 and THY1 pathways. Lineage tracing reveals that Myh11+ mural cells coordinate angiogenesis during disc injury but lost their progenitor characteristics and ultimately become Sfrp2+ non-chondrogenic fibroblasts instead of Chad+ chondrogenic fibroblasts. Overall, we reveal multiple insights into the coordinated development of disc cells and are the first to describe the resident mural cell progenitor during disc injury.

Activation of a transient progenitor state in the epicardium is required for zebrafish heart regeneration

The epicardium, a mesothelial cell tissue that encompasses vertebrate hearts, supports heart regeneration after injury through paracrine effects and as a source of multipotent progenitors. However, the progenitor state in the adult epicardium has yet to be defined. Through single-cell RNA-sequencing of isolated epicardial cells from uninjured and regenerating adult zebrafish hearts, we define the epithelial and mesenchymal subsets of the epicardium. We further identify a transiently activated epicardial progenitor cell (aEPC) subpopulation marked by ptx3a and col12a1b expression. Upon cardiac injury, aEPCs emerge from the epithelial epicardium, migrate to enclose the wound, undergo epithelial-mesenchymal transition (EMT), and differentiate into mural cells and pdgfra+hapln1a+ mesenchymal epicardial cells. These EMT and differentiation processes are regulated by the Tgfβ pathway. Conditional ablation of aEPCs blocks heart regeneration through reduced nrg1 expression and mesenchymal cell number. Our findings identify a transient progenitor population of the adult epicardium that is indispensable for heart regeneration and highlight it as a potential target for enhancing cardiac repair.

Dissociation of Cerebellar Granule Neuron Progenitors for Culture, FACS, Transcriptomics, and Molecular Biology.

Brain growth reflects the proliferation dynamics of neural progenitors, and understanding brain growth requires molecular, genetic, and functional studies of these specific cells. Cerebellar granule neuron progenitors (CGNPs) proliferate in the early postnatal period in both mice and humans, to generate the largest population of neurons in the central nervous system. CGNPs present a large, spatially segregated source of neural progenitors with a consistent, well-characterized temporal pattern of proliferation and differentiation that facilitates analysis. Dissociating of CGNPs with the methods below will generate a suspension of primary neural progenitors harvested from the postnatal brain that may be used for diverse experimental analyses including cell culture, protein extraction, flow cytometry, metabolomic analysis, and transcriptomic analysis with single-cell resolution (scRNA-seq).

Micro-fragmented adipose tissue cellular composition varies by processing device and analytical method

Autologous adipose-derived biologics are of clinical interest based on accessibility of adipose tissue, a rich source of progenitor and immunomodulatory cells. Micro-fragmented adipose tissue (MFAT) preserves the cellular niche within intact extracellular matrix, potentially offering benefit over enzymatically-liberated stromal vascular fraction (SVF), however lack of standardized analyses complicate direct comparison of these products. In this study, MFAT from LipoGems® and AutoPose™ Restore systems, which utilize different washing and resizing methods, was analyzed for cellular content using different techniques. Flow cytometry was performed on SVF, with or without culture, and on the adherent cell population that naturally migrated from undigested MFAT. Cytokine release during culture was also assessed. SVF contained more diverse progenitor populations, while MFAT outgrowth contained lower cell concentrations of predominantly mesenchymal stromal cells (MSC). MSCs were significantly higher in MFAT from the AutoPose System for all analyses, with increased cytokine secretion characterized by high levels of anti-inflammatory and low to non-detectable inflammatory cytokines. These results demonstrate that cellularity depends on MFAT processing methods, and different techniques can be employed to evaluate graft cellularity. Comparisons of cell concentrations determined via these methods could be used to better interpret inter-study variability.

Searching for the next Galactic Luminous red nova

ABSTRACT Luminous red novae (LRNe) are astrophysical transients believed to be caused by the partial ejection of a binary star’s common envelope (CE) and the merger of its components. The formation of the CE is likely to occur during unstable mass transfer, initiated by a primary star which is evolving off the main sequence (a Hertzsprung gap star) and a lower mass companion. In agreement with observations, theoretical studies have shown that outflows from the pre-CE phase produce a detectable brightening of the progenitor system a few years before the ejection event. Based on these assumptions, we present a method to identify Galactic LRNe precursors, the resulting precursor candidates, and our follow-up analysis to uncover their nature. We begin by constructing a sample of progenitor systems, i.e. Hertzsprung gap stars, by statistically modelling the density of a colour magnitude diagram formed from ‘well behaved’ Gaia DR2 sources. Their time-domain evolution from the Zwicky Transient Facility (ZTF) survey is used to search for slowly brightening events, as pre-CE precursor candidates. The nature of the resulting candidates is further investigated using archival data and our own spectroscopic follow-up. Overall, we constructed a sample of ∼5.4 × 104 progenitor sources, from which 21 were identified as candidate LRNe precursors. Further analysis revealed 16 of our candidates to be Hα emitters, with their spectra often suggesting hotter (albeit moderately extincted) A-type or B-type stars. Because of their long-term variability in optical and mid-infrared wavelengths, we propose that many of our candidates are mass-transferring binaries with compact companions surrounded by dusty circumstellar discs or alternatively magnetically active stellar merger remnants.