Characterization Of Progenitor Cells Research Articles

Receptor tyrosine kinase inhibitors negatively impact on pro-reparative characteristics of human cardiac progenitor cells

Receptor tyrosine kinase inhibitors improve cancer survival but their cardiotoxicity requires investigation. We investigated these inhibitors’ effects on human cardiac progenitor cells in vitro and rat heart in vivo. We applied imatinib, sunitinib or sorafenib to human cardiac progenitor cells, assessing cell viability, proliferation, stemness, differentiation, growth factor production and second messengers. Alongside, sunitinib effects were assessed in vivo. Inhibitors decreased (p < 0.05) cell viability, at levels equivalent to ‘peak’ (24 h; imatinib: 91.5 ± 0.9%; sunitinib: 83.9 ± 1.8%; sorafenib: 75.0 ± 1.6%) and ‘trough’ (7 days; imatinib: 62.3 ± 6.2%; sunitinib: 86.2 ± 3.5%) clinical plasma levels, compared to control (100% viability). Reduced (p < 0.05) cell cycle activity was seen with imatinib (29.3 ± 4.3% cells in S/G2/M-phases; 50.3 ± 5.1% in control). Expression of PECAM-1, Nkx2.5, Wnt2, linked with cell differentiation, were decreased (p < 0.05) 2, 2 and 6-fold, respectively. Expression of HGF, p38 and Akt1 in cells was reduced (p < 0.05) by sunitinib. Second messenger (p38 and Akt1) blockade affected progenitor cell phenotype, reducing c-kit and growth factor (HGF, EGF) expression. Sunitinib for 9 days (40 mg/kg, i.p.) in adult rats reduced (p < 0.05) cardiac ejection fraction (68 ± 2% vs. baseline (83 ± 1%) and control (84 ± 4%)) and reduced progenitor cell numbers. Receptor tyrosine kinase inhibitors reduce cardiac progenitor cell survival, proliferation, differentiation and reparative growth factor expression.

Abstract 4005: Identification of IGF2 as genomic driver and actionable therapeutic target in hepatoblastoma

Abstract Background and Aims: Management of hepatoblastoma (HB), the most frequent pediatric liver cancer, is based on surgical resection and perioperative platin-based regimens, commonly cisplatin. Here, we aimed to identify actionable targets in HB and assess the efficacy of molecular therapies in HB cell lines, organoids and murine models. Methods: Paired tumor and adjacent tissues from 31 resected HBs and a validation set of 50 HBs were analyzed at the transcriptomic, genomic and epigenomic level using RNAseq, SNP and methylation arrays, respectively. The main targetable driver in HB was identified by gene co-expression network analysis (GCN) and its overexpression was confirmed by qRT-PCR. The anti-tumor effect of driver inhibition with molecular therapies alone or in combination with cisplatin was assessed in cell lines, patient-derived HB organoids and in a HB xenograft murine model. Results: IGF2 overexpression (FC&amp;gt; 4 vs adjacent tissue) was identified as the top targetable HB driver (71%, 22/31). IGF2high tumors displayed progenitor cell features and were significantly enriched in molecular classes with aggressive phenotypes and CTNNB1 mutations, while IGF2low tumors were enriched in inflammatory and TGF-β signaling. IGF2high tumors correlated with shorter recurrence-free survival after resection (median 34 months vs not reached for IGF2low; p = 0.02). IGF2 overexpression correlated in most cases (86%) with fetal promoter hypomethylation (50%), 11p15.5 loss of heterozygosity (LOH, 57%) or overexpression of miR483 (55%). Xentuzumab (anti-IGF1/2 mAb) alone or combined with cisplatin reduced proliferation and clonogenic capacity in IGF2high cell lines. The combination of xentuzumab and cisplatin exhibited synergistic effects in terms of cell viability in organoids derived from IGF2high human HBs. In mice, this combination induced a significant decrease in the viable tumor volume and extended survival compared to cisplatin alone (n = 13-14 per arm, p = 0.04). Conclusion: IGF2 is an actionable driver in HB and its overexpression was associated with fetal promoter hypomethylation, LOH or miR483 overexpression. The combination of a mAb against IGF1/2 (xentuzumab) with cisplatin led to remarkable anti-tumoral effects in pre-clinical models, providing the rationale for exploring this regimen in IGF2high HB patients. Citation Format: Jordi Abril-Fornaguera, Laura Torrens, Juan Carrillo-Reixach, Alexander Rialdi, Ugne Balaseviciute, Carla Montironi, Philipp Haber, Álvaro Del Río-Álvarez, Montserrat Domingo-Sàbat, Laura Royo, Nicholas Akers, Catherine E. Willoughby, Judit Peix, Miguel Torres-Martin, Marc Puigvehi, Roser Pinyol, Stefano Cairo, Margaret Childs, Rudolf Maibach, Rita Alaggio, Piotr Czauderna, Bruce Morland, Bojan Losic, Vincenzo Mazzaferro, Ernesto Guccione, Daniela Sia, Carolina Armengol, Josep M. Llovet. Identification of IGF2 as genomic driver and actionable therapeutic target in hepatoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4005.

Obesity Affects the Proliferative Potential of Equine Endometrial Progenitor Cells and Modulates Their Molecular Phenotype Associated with Mitochondrial Metabolism.

The study aimed to investigate the influence of obesity on cellular features of equine endometrial progenitor cells (Eca EPCs), including viability, proliferation capacity, mitochondrial metabolism, and oxidative homeostasis. Eca EPCs derived from non-obese (non-OB) and obese (OB) mares were characterized by cellular phenotype and multipotency. Obesity-induced changes in the activity of Eca EPCs include the decline of their proliferative activity, clonogenic potential, mitochondrial metabolism, and enhanced oxidative stress. Eca EPCs isolated from obese mares were characterized by an increased occurrence of early apoptosis, loss of mitochondrial dynamics, and senescence-associated phenotype. Attenuated metabolism of Eca EPCs OB was related to increased expression of pro-apoptotic markers (CASP9, BAX, P53, P21), enhanced expression of OPN, PI3K, and AKT, simultaneously with decreased signaling stabilizing cellular homeostasis (including mitofusin, SIRT1, FOXP3). Obesity alters functional features and the self-renewal potential of endometrial progenitor cells. The impaired cytophysiology of progenitor cells from obese endometrium predicts lower regenerative capacity if used as autologous transplants.

Impact of Microenvironmental Changes during Degeneration on Intervertebral Disc Progenitor Cells: A Comparison with Mesenchymal Stem Cells.

Intervertebral disc (IVD) degeneration occurs with natural ageing and is linked to low back pain, a common disease. As an avascular tissue, the microenvironment inside the IVD is harsh. During degeneration, the condition becomes even more compromised, presenting a significant challenge to the survival and function of the resident cells, as well as to any regeneration attempts using cell implantation. Mesenchymal stem cells (MSCs) have been proposed as a candidate stem cell tool for IVD regeneration. Recently, endogenous IVD progenitor cells have been identified inside the IVD, highlighting their potential for self-repair. IVD progenitor cells have properties similar to MSCs, with minor differences in potency and surface marker expression. Currently, it is unclear how IVD progenitor cells react to microenvironmental factors and in what ways they possibly behave differently to MSCs. Here, we first summarized the microenvironmental factors presented in the IVD and their changes during degeneration. Then, we analyzed the available studies on the responses of IVD progenitor cells and MSCs to these factors, and made comparisons between these two types of cells, when possible, in an attempt to achieve a clear understanding of the characteristics of IVD progenitor cells when compared to MSCs; as well as, to provide possible clues to cell fate after implantation, which may facilitate future manipulation and design of IVD regeneration studies.

Roots of the Malformations of Cortical Development in the Cell Biology of Neural Progenitor Cells.

The cerebral cortex is a structure that underlies various brain functions, including cognition and language. Mammalian cerebral cortex starts developing during the embryonic period with the neural progenitor cells generating neurons. Newborn neurons migrate along progenitors’ radial processes from the site of their origin in the germinal zones to the cortical plate, where they mature and integrate in the forming circuitry. Cell biological features of neural progenitors, such as the location and timing of their mitoses, together with their characteristic morphologies, can directly or indirectly regulate the abundance and the identity of their neuronal progeny. Alterations in the complex and delicate process of cerebral cortex development can lead to malformations of cortical development (MCDs). They include various structural abnormalities that affect the size, thickness and/or folding pattern of the developing cortex. Their clinical manifestations can entail a neurodevelopmental disorder, such as epilepsy, developmental delay, intellectual disability, or autism spectrum disorder. The recent advancements of molecular and neuroimaging techniques, along with the development of appropriate in vitro and in vivo model systems, have enabled the assessment of the genetic and environmental causes of MCDs. Here we broadly review the cell biological characteristics of neural progenitor cells and focus on those features whose perturbations have been linked to MCDs.

Morphofunctional Features of Hematopoietic Bone Marrow Progenitor Cells in Patients with Chronic Myeloid Leukemia in Long-Term Culture of Gel Diffusion Chambers In Vivo

Morphofunctional Features of Hematopoietic Bone Marrow Progenitor Cells in Patients with Chronic Myeloid Leukemia in Long-Term Culture of Gel Diffusion Chambers In Vivo

Leukemic progenitor cells enable immunosuppression and post-chemotherapy relapse via IL-36-inflammatory monocyte axis.

Chemotherapy can effectively reduce the leukemic burden and restore immune cell production in most acute myeloid leukemia (AML) cases. Nevertheless, endogenous immunosurveillance usually fails to recover after chemotherapy, permitting relapse. The underlying mechanisms of this therapeutic failure have remained poorly understood. Here, we show that abnormal IL-36 production activated by NF-κB is an essential feature of mouse and human leukemic progenitor cells (LPs). Mechanistically, IL-36 directly activates inflammatory monocytes (IMs) in bone marrow, which then precludes clearance of leukemia mediated by CD8+ T cells and facilitates LP growth. While sparing IMs, common chemotherapeutic agents stimulate IL-36 production from residual LPs via caspase-1 activation, thereby enabling the persistence of this immunosuppressive IL-36–IM axis after chemotherapy. Furthermore, IM depletion by trabectedin, with chemotherapy and PD-1 blockade, can synergistically restrict AML progression and relapse. Collectively, these results suggest inhibition of the IL-36–IM axis as a potential strategy for improving AML treatment.

Analysis of Patient Factors Affecting In Vitro Characteristics of Subacromial Bursal Connective Tissue Progenitor Cells during Rotator Cuff Repair.

Unsatisfactory failure rates following rotator cuff (RC) repair have led orthopaedic surgeons to explore biological augmentation of the healing enthesis. The subacromial bursa (SB) contains abundant connective tissue progenitor cells (CTPs) that may aid in this process. The purpose of the study was to investigate the influence of patient demographics and tear characteristics on the number of colony-forming units (CFUs) and nucleated cell count (NCC) of SB-derived CTPs. In this study, we harvested SB tissue over the supraspinatus tendon and muscle in 19 patients during arthroscopic RC repair. NCC of each sample was analyzed on the day of the procedure. After 14 days, CFUs were evaluated under a microscope. Spearman’s rank correlation coefficient was then used to determine the relationship between CFUs or NCC and patient demographics or tear characteristics. The study found no significant correlation between patient demographics and the number of CFUs or NCC of CTPs derived from the SB (p > 0.05). The study did significantly observe that increased tear size was negatively correlated with the number of CFUs (p < 0.05). These results indicated that increased tear size, but not patient demographics, may influence the viability of CTPs and should be considered when augmenting RCrepairs with SB.

Tendon-Derived Progenitor Cells With Multilineage Potential Are Present Within Human Patellar Tendon.

Background:Progenitor cells serve as a promising source of regenerative potential in a variety of tissue types yet remain underutilized in tendinopathy. Tendon-derived progenitor cells (TDPCs) have previously been isolated from hamstring tendon but only as part of a concomitant medical procedure. Determining the presence of TDPCs in patellar tendon may facilitate clinical utilization of these cells because of the relative accessibility of this location for tissue harvest.Purpose:To characterize TDPCs in human patellar tendon samples.Study Design:Descriptive laboratory study.Methods:Human patellar tendon samples were obtained during elective knee surgery. TDPCs were isolated and seeded at an optimal low cell density and subcultured to confluence for up to 2 passages. Flow cytometry was used to analyze for the expression of CD90+, CD105+, CD44+, and CD31–, CD34–, and CD45– markers. The multilineage differentiation potential of TDPCs was tested in vitro via adipogenic, osteogenic, and chondrogenic culture with subsequent cytochemical staining for Oil Red O, Alizarin Red, and Alcian Blue, respectively. Enzyme-linked immunosorbent assay was used to quantify the amount of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 secreted into cell culture supernatant for further confirmation of lineage differentiation. Results were analyzed statistically using the 2-tailed Student t test.Results:TDPCs demonstrated near-uniform expression of CD90, CD105, and CD44 with minimal expression of CD34, CD31, and CD45. Adipogenic, osteogenic, and chondrogenic differentiation of TDPCs was confirmed using qualitative analysis. The expression of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 were significantly increased in differentiated cells versus undifferentiated TDPCs (P < .05).Conclusion:TDPCs can be successfully isolated from human patellar tendon samples, and they exhibit characteristics of multipotent progenitor cells.Clinical Relevance:These data demonstrate the promise of patellar tendon tissue as a source of progenitor cells for use in biologic therapies for the treatment of tendinopathy.

Bone marrow stromal cells (BMSCs CD45- /CD44+ /CD73+ /CD90+ ) isolated from osteoporotic mice SAM/P6 as a novel model for osteoporosis investigation.

Available therapies aimed at treating age‐related osteoporosis are still insufficient. Therefore, designing reliable in vitro model for the analysis of molecular mechanisms underlying senile osteoporosis is highly required. We have isolated and characterized progenitor cells isolated from bone marrow (BMSCs) of osteoporotic mice strain SAM/P6 (BMSCSAM/P6). The cytophysiology of BMSCSAM/P6 was for the first time compared with BMSCs isolated from healthy BALB/c mice (BMSCBALB/c). Characterization of the cells included evaluation of their multipotency, morphology and determination of specific phenotype. Viability of BMSCs cultures was determined in reference to apoptosis profile, metabolic activity, oxidative stress, mitochondrial membrane potential and caspase activation. Additionally, expression of relevant biomarkers was determined with RT‐qPCR. Obtained results indicated that BMSCSAM/P6 and BMSCBALB/c show the typical phenotype of mesenchymal stromal cells (CD44+, CD73+, CD90+) and do not express CD45. Further, BMSCSAM/P6 were characterized by deteriorated multipotency, decreased metabolic activity and increased apoptosis occurrence, accompanied by elevated oxidative stress and mitochondria depolarisation. The transcriptome analyses showed that BMSCSAM/P6 are distinguished by lowered expression of molecules crucial for proper osteogenesis, including Coll‐1, Opg and Opn. However, the expression of Trap, DANCR1 and miR‐124‐3p was significantly up‐regulated. Obtained results show that BMSCSAM/P6 present features of progenitor cells with disturbed metabolism and could serve as appropriate model for in vitro investigation of age‐dependent osteoporosis.

Aging of the progenitor cells that initiate prostate cancer.

Many organs experience a loss of tissue mass and a decline in regenerative capacity during aging. In contrast, the prostate continues to grow in volume. In fact, age is the most important risk factor for prostate cancer. However, the age-related factors that influence the composition, morphology and molecular features of prostate epithelial progenitor cells, the cells-of-origin for prostate cancer, are poorly understood. Here, we review the evidence that prostate luminal progenitor cells are expanded with age. We explore the age-related changes to the microenvironment that may influence prostate epithelial cells and risk of transformation. Finally, we raise a series of questions about models of aging and regulators of prostate aging which need to be addressed. A fundamental understanding of aging in the prostate will yield critical insights into mechanisms that promote the development of age-related prostatic disease.

Heterogeneity of glial progenitor cells during the neurogenesis-to-gliogenesis switch in the developing human cerebral cortex

The heterogeneity and molecular characteristics of progenitor cells, especially glial progenitors, in the developing human cerebral cortex remain elusive. Here, we find that EGFR expression begins to sharply increase after gestational week (GW) 20, which corresponds to the beginning stages of human gliogenesis. In addition, EGFR+ cells are mainly distributed in the germinal zone and frequently colocalize with the stemness marker SOX2 during this period. Then, by performing single-cell RNA sequencing on these EGFR+ cells, we successfully enriched and characterized various glial- and neuronal-lineage progenitor cells and validated their phenotypes in fixed slices. Notably, we identified two subgroups with molecular characteristics similar to those of astrocytes, and the immunostaining results show that these cells are mainly distributed in the outer subventricular zone and might originate from the outer radial glial cells. In short, the EGFR-sorting strategy and molecular signatures in the diverse lineages provide insights into human glial development.

Isolation and Multiple Differentiation of Rat Pericardial Fluid Cells.

ObjectiveThe aim of the present study is to isolate and analyze the characterization of pericardial fluid cells (PFCs) from rat and provides a morphological basis for the basic research and clinical application of PFCs.MethodsAfter aseptic thoracotomy was performed, normal saline was injected into the pericardial cavity of 50 adult Sprague–Dawley rats. The mixture of diluted pericardial fluid was extracted, centrifuged, and cultured. The cell morphology of different generations in the pericardial fluid was observed on an inverted microscope. The expression levels of CD44, CD29, CD90, and pan-hematopoietic marker CD45 were analyzed via flow cytometry. The third-generation cells were used for osteogenic, adipogenic, and cardiac differentiation.ResultsPFCs were successfully isolated and subcultured. PFCs were predominantly circular in shape after 24 h of culture. Following subculture for 3 days, the cells demonstrated a spindle shape. The rat pericardial fluid contains cell populations with uniform morphology, good growth state, and strong proliferation ability. Flow cytometry results showed that CD29 (100%) and CD90 (99.3%) were positively expressed, whereas CD45 (0.30%) and CD44 (0.48%) were negatively expressed. The PFCs could differentiate into osteoblasts and adipocytes after being induced. Cardiac differentiation was also confirmed by cardiac troponin T (cTnT) and α-sarcomeric actin (α-SA) staining.ConclusionThis study revealed that a subpopulation of cells was isolated from pericardial fluid, which exhibited progenitor cell features and multiple differentiation potency. PFCs could serve as an alternative cell source for myocardial tissue repair, engineering, and reconstruction.

Proliferative capacity of retinal progenitor cells in human fetal retina

Introduction: Retina is an innermost, delicate, and photosensitive layer of the eyeball, which is composed of 10 layers and 8 specialized cells which are involved in paramount function of the body like vision. Retinal neurogenesis commences from the layers of optic cup, which forms from optic vesicle. Progenitor cells are the tissue-specific cells which give rise to all different types of retinal cells. Progenitor cells in fetal retina proliferate at specific time during development of retina. Knowledge of the highest proliferative capacity interval of progenitor cells will be valuable for transplantation. Material and Methods: Twenty-eight fetuses of spontaneous abortions of 13th–40th week were collected from MGM Hospital after ethical and scientific approval of the institute. After fixation of fetuses, eyeballs were extracted and fixed in buffer solution. Sections were taken and the retina was treated with Ki-67 immunohistochemistry marker to observe proliferative capacity of retinal progenitor cells (RPCs). Seven groups (A to G) of 4 weeks were made and observations of each group were noted. Results: It was observed that the highest proliferative capacity of RPCs was in B group (17–20 weeks) and the highest proliferative capacity of RPCs was maximum at 19th week of gestation. Discussion and Conclusion: Characteristics of progenitor cells in retina are well studied. Their highest proliferation period can be utilized to make the procedure of transplantation more refined.

The Bone-Forming Properties of Periosteum-Derived Cells Differ Between Harvest Sites.

The development of alternatives for autologous bone grafts is a major focus of bone tissue engineering. To produce living bone-forming implants, skeletal stem and progenitor cells (SSPCs) are envisioned as key ingredients. SSPCs can be obtained from different tissues including bone marrow, adipose tissue, dental pulp, and periosteum. Human periosteum-derived cells (hPDCs) exhibit progenitor cell characteristics and have well-documented in vivo bone formation potency. Here, we have characterized and compared hPDCs derived from tibia with craniofacial hPDCs, from maxilla and mandible, respectively, each representing a potential source for cell-based tissue engineered implants for craniofacial applications. Maxilla and mandible-derived hPDCs display similar growth curves as tibial hPDCs, with equal trilineage differentiation potential toward chondrogenic, osteogenic, and adipogenic cells. These craniofacial hPDCs are positive for SSPC-markers CD73, CD164, and Podoplanin (PDPN), and negative for CD146, hematopoietic and endothelial lineage markers. Bulk RNA-sequencing identified genes that are differentially expressed between the three sources of hPDC. In particular, differential expression was found for genes of the HOX and DLX family, for SOX9 and genes involved in skeletal system development. The in vivo bone formation, 8 weeks after ectopic implantation in nude mice, was observed in constructs seeded with tibial and mandibular hPDCs. Taken together, we provide evidence that hPDCs show different profiles and properties according to their anatomical origin, and that craniofacial hPDCs are potential sources for cell-based bone tissue engineering strategies. The mandible-derived hPDCs display - both in vitro and in vivo - chondrogenic and osteogenic differentiation potential, which supports their future testing for use in craniofacial bone regeneration applications.

Activity of the human immortalized endothelial progenitor cell line HEPC-CB.1 supporting in vitro angiogenesis

The human HEPC-CB.1 cell line with many characteristics of endothelial progenitor cells (EPC) was tested for its proangiogenic properties as a potentially therapeutic compound. HEPC-CB.1 cells’ potential to differentiate into endothelial cells was revealed after treating the cells with a mixture of ATRA, cAMP and VEGF, as shown by the reduced expression levels of CD133, CD271 and CD90 antigens, augmentation of CD146 and CD31, and a decrease in cell clonogenicity. The cooperation of HEPC-CB.1 with the endothelial cell line HSkMEC.2 resulted in the formation of a common network. Tube formation was significantly more effective when resulting from HEPC-CB.1 and HSkMEC.2 cell co-culture as compared to a monoculture of each cell line. The exocrine mechanism of HEPC-CB.1 and HSkMEC.2 cross talk by secreted factors was evidenced using the HEPC-CB.1 supernatant to increase the efficacy of HSkMEC.2 tube formation. The proangiogenic factors produced by HEPC-CB.1 were identified using cytokine antibody array. Out of 120 examined factors, the HEPC-CB.1 cell line produced 63, some with known angiogenic activity. As in vivo the angiogenic process occurs at low oxygen tension, it was observed that in hypoxia, the production of defined factors was augmented. The presented results demonstrate that HEPC-CB.1 cells are able to both cooperate and integrate in a newly formed network and produce factors that help the network formation. The results suggest that HEPC-CB.1 cells are indeed endothelial progenitors and may prove to be an effective tool in regenerative medicine.

Purification and Functional Characterization of CD34-Expressing Cell Subsets Following Ex Vivo Expansion of Umbilical Cord Blood-Derived Endothelial Colony-Forming Cells.

Fluorescent-activated cell sorting (FACS) remains a powerful tool to enrich blood-derived progenitor cells for the establishment of highly proliferative endothelial colony-forming cells (ECFC). Further investigation remains necessary to determine whether the retention of progenitor cell phenotypes after expansion can identify ECFC with enhanced proangiogenic and regenerative functions. This study employed FACS purification to segregate umbilical cord blood-derived ECFC using conserved provascular progenitor cell markers CD34 or aldehyde dehydrogenase (ALDH) activity. ECFC FACS purified for high versus low ALDH activity formed single cell-derived colonies and demonstrated tubule formation in Matrigel at comparable rates. Surprisingly, FACS purification of ECFC for CD34 enriched cells with enhanced colony-forming capabilities and tubule formation within the CD34- population. CD34 expression was enriched on early ECFC populations; however, steady-state expression of CD34 rapidly declined and stabilized on expanded ECFC after serial passage. CD34 expression on ECFC was shown to be cell density dependent and coincided with a loss of progenitor cell characteristics in vitro. Silica-bead surface membrane capture followed by proteomic analysis by label-free liquid chromatography tandem mass spectrometry (LC-MS/MS) identified >100 distinctions (P < 0.05) associated with the plasma membrane of CD34- versus CD34+ ECFC, including a significant enrichment of CD143 (angiotensinogen converting enzyme) on CD34+ cells. Despite an enrichment for traditional endothelial cell markers on the CD34+ ECFC in vitro, implantation of both CD34+ and CD34- ECFC within Matrigel plugs in immunodeficient NOD.SCID mice promoted the formation of vessel-like structures with equivalent integration of human cells at 7 days post-transplantation. Although positive selection of CD34 enriched ECFC establishment before culture, FACS-purified CD34+ ECFC demonstrated reduced colony and tubule formation in vitro, yet demonstrated equivalent vessel formative function in vivo compared to CD34- counterparts. The knowledge will support future studies aiming to identify ECFC subsets with enhanced vessel forming functions for applications of regenerative medicine.

Centrosome anchoring regulates progenitor properties and cortical formation.

SUMMARYRadial glial progenitors (RGPs) represent the major neural progenitors for generating neurons and glia in the developing mammalian cerebral cortex 1-3. They position their centrosomes away from the nucleus at the ventricular zone surface 4-7. However, the molecular basis and precise function of this highly unique and characteristic subcellular organization of the centrosome remain largely unknown. Here we show that apical membrane anchoring of the centrosome controls the mechanical properties of mouse cortical RGPs and consequently their mitotic behaviour and cortical size and formation. Mother centriole in RGPs specifically develops distal appendages to anchor to the apical membrane. Selective removal of Centrosomal protein 83 (CEP83) eliminates mother centriole distal appendages and disrupts centrosome apical membrane anchorage, resulting in microtubule disorganization and apical membrane stretching and stiffening. It activates mechanically-sensitive Yes-associated protein (YAP) and promotes excessive RGP proliferation and subsequent intermediate progenitor overproduction, leading to the formation of an enlarged cortex with abnormal folding. Simultaneous elimination of YAP suppresses cortical enlargement and folding caused by CEP83 removal. Together, these results uncover a previously unknown role of the centrosome in regulating the mechanical features of neural progenitors, and the size and configuration of the mammalian cerebral cortex.

Murine hepatoblast-derived liver tumors resembling human combined hepatocellular-cholangiocarcinoma with stem cell features

BackgroundCombined hepatocellular-cholangiocarcinoma (CHC) is a primary hepatic malignancy with heterogeneously combined histological features of putative hepatic progenitor cells (HPC) origin. We describe a mouse model that exhibits the heterogenous histological and phenotypic finding similar to human CHC.MethodsWe injected hepatoblasts isolated from p53−/− C57BL/6 mice into syngeneic wild-type pre-conditioned C57BL/6 mice. We confirmed that p53−/− murine hepatoblasts act as tumor-initiating cells (TICs) that generate CHC both in situ and within metastases. For comparative pathological study, 8 human cases of CHC with stem cell features were recruited by immunohistochemistry and multicolor fluorescence immunostaining.ResultsWe identified corresponding areas in murine tumors matching each WHO criteria-described subtype of human CHC. In both murine and human tumors, HPC-like cells in tumor nests and associated stem cell features/traits are suggested histologically to be the progenitor origin of the cancerConclusionsThe pathological characteristics of murine tumors recapitulate human CHC with stem cell features. These data provide additional comparative pathological evidence that CHC with stem cell features originate from HPCs and validate a model to study this cancer type in vivo.

Characteristics of Bone Marrow Progenitor Cells of C57BL/6N Mice after 30-Day Hindlimb Suspension and 12-Hour Readaptation to Support Loading

The functional status of bone marrow (BM) progenitor cells, which provide hematopoiesis and homeostasis of bone tissue, determines many processes which take a place in spaceflight (SF) and subsequent recovery to gravity. It is known that SF factors and simulation of their effects do irreversible damage to the pool of hematopoietic and stromal progenitor cells. Meanwhile, changes in the functional activity of BM progenitor cells after simulation of SF effects were more pronounced than in the case of a real SF. The aim of the study was to examine processes of recovery of the functional activity of BM progenitor cells during readaptaion to loading after 30-day hindlimb suspension. Studies were performed on three groups of male mice: vivarium control, suspension, and readaptation. The following characteristics were monitored: number of nucleated BM cells, immunophenotype, proliferative activity of stromal BM cells, number of hematopoietic colony-forming units (CFU), CFUs of fibroblasts, and differentiating capabilities of BM hematopoietic and stromal precursors. Hindlimb suspension resulted in decreased number of fibroblast and hematopoietic CFU, inhibition of spontaneous osteodifferentiation of stromal progenitors and decreased expression of stromal markers. The readaptaion period was accompanied with restoration of the functional activity of stromal progenitors, while complete recovery of hematopoiesis was not observed.