Cell-free Stem Cell-Derived Extract Formulation for Regenerative Medicine Applications.

Stem cells for regenerative medicine purposes offer therapeutic benefits, but disadvantages are still ill defined. The benefit of stem cells may be attributed to their secretion of growth factors (GFs), cytokines (CKs), and extracellular vesicles (EVs), including exosomes. We present a novel cell-free stem cell-derived extract (CCM), formulated from human progenitor endothelial stem cells (hPESCs), characterized for biologically active factors using ELISA, nanoparticle tracking analysis and single particle interferometric reflectance imaging sensing. The effect on fibroblast proliferation and ability to induce stem cell migration was analyzed using Alamar Blue proliferation and Transwell migration assays, respectively. GFs including IGFBP 1, 2, 3, and 6, insulin, growth hormone, PDGF-AA, TGF-α, TGF-ß1, VEGF, and the anti-inflammatory cytokine, IL-1RA were detected. Membrane enclosed particles within exosome size range and expressing exosome tetraspanins CD81 and CD9 were identified. CCM significantly increased cell proliferation and induced stem cell migration. Analysis of CCM revealed presence of GFs, CKs, and EVs, including exosomes. The presence of multiple factors including exosomes within one formulation, the ability to promote cell proliferation and induce stem cell migration may reduce inflammation and pain, and augment tissue repair.

MRI tracing of ultrasmall superparamagnetic iron oxide nanoparticle­labeled endothelial progenitor cells for repairing atherosclerotic vessels in rabbits.

Endothelial progenitor cells (EPCs) have been discovered to be relevant to the prognosis of cardiovascular diseases. Previous research has demonstrated that EPCs serve vital roles in the occurrence and development of atherosclerosis. Significant improvements have been made in MRI technology and in the experimental use of EPCs for therapeutic angiogenesis and vascular repair. Nevertheless, the migratory, adhesive, proliferative and angiogenic properties of EPCs remain unknown. The aims of the present study were to investigate the potential of using non­invasive monitoring with ultrasmall superparamagnetic iron oxide nanoparticle (USPION)­labeled endothelial progenitor cells (EPCs) after transplantation, and to assess the treatment outcomes in an atherosclerotic rabbit model. EPCs derived from rabbit peripheral blood samples were labeled with USPION­poly­l­lysine (USPION­PLL). The morphology, proliferation, adhesive ability and labeling efficiency of the EPCs were determined by optical and electron microscopy. Moreover, biological activity was assessed by flow cytometry. In addition, T2­weighted image fast spin­echo MRI was used to detect cell labeling. USPION content in the labeled EPCs was determined by Prussian blue staining and scanning electron microscopy. Rabbit atherosclerosis model was established using a high­fat diet. USPION­labeled EPCs were transplanted into rabbits, and in vivo MRI was performed 1 and 7 days after transplantation. It was found that EPCs cultured on Matrigel formed capillary­like structures, and expressed the surface markers CD133, CD31, CD34 and vascular endothelial growth factor receptor 2 (VEGFR2). The optimal USPION concentration was 32 µg/ml, as determined by adhesion and proliferation assays. It was identified that USPION­PLL nanoparticles were 10­20 nm in diameter. Histopathological analysis results indicated that 1 day after transplantation of the labeled EPCs, blue­stained granules were observed in the intima of vascular lesions in rabbit models after Prussian blue staining. Therefore, the present results suggest that USPION­labeled EPCs may play a role in repairing endothelial injury and preventing atherosclerosis in vivo.

Extracellular vesicles from endothelial progenitor cells prevent steroid-induced osteoporosis by suppressing the ferroptotic pathway in mouse osteoblasts based on bioinformatics evidence.

Abnormal antioxidative capabilities were observed in the pathogenesis of steroid-induced osteoporosis (SIOP). Ferroptosis is a recently discovered type of cell death that is characterized by the overproduction of ROS in response to GPX4 and system Xc- downregulation, which is mediated by an Fe2+ fenton reaction. However, investigations focusing on the relationship between ferroptosis and steroid-induced bone disease remain limited. In the present study, high-dose dexamethasone was used to establish a mouse SIOP model, and extracellular vesicles extracted from bone marrow-derived endothelial progenitor cells (EPC-EVs) alleviated the pathological changes in SIOP via microtomography (micro-CT), with elevations in bone volume (BV), bone surface (BS), trabecular thickness (Tb.Th), and trabecular connectivity density (Conn-D) and decreases in trabecular separation (Tb.sp) and the structure model index (SMI). Histopathological analysis, such as haematoxylin and eosin (HE) and Masson staining, showed that EPC-EVs treatment increased the volume and density of the trabecular bone and bone marrow. RNA sequencing (RNA-seq) and bioinformatics analysis revealed subcellular biological alterations upon steroid and EPC-EVs treatment. Compared with the control, high-dose dexamethasone downregulated GPX4 and system XC-, and the Kyoto Encyclopedia of Genes and Genomes (KEGG)-based gene set enrichment analysis suggested that the ferroptotic pathway was activated. In contrast, combination treatment with EPC-EVs partly reversed the KEGG-mapped changes in the ferroptotic pathway at both the gene and mRNA expression levels. In addition, alterations in ferroptotic marker expression, such as SLC3A2, SLC7A11, and GPX4, were further confirmed by RNA-seq. EPC-EVs were able to reverse dexamethasone treatment-induced alterations in cysteine and several oxidative injury markers, such as malondialdehyde (MDA), glutathione (GSH), and glutathione disulphide (GSSG) (as detected by ELISA). In conclusion, EPC-EVs prevented mouse glucocorticoid-induced osteoporosis by suppressing the ferroptotic pathway in osteoblasts, which may provide a basis for novel therapies for SIOP in humans.

Endothelial progenitor cell-derived exosomes facilitate vascular endothelial cell repair through shuttling miR-21-5p to modulate Thrombospondin-1 expression.

Background: Our previous studies observed that administration of exosomes from endothelial progenitor cells (EPC) facilitated vascular repair in the rat model of balloon injury. However, the molecular events underlying this process remain elusive. Here, we aim to interrogate the key miRNAs within EPC-derived exosomes (EPC-exosomes) responsible for the activation of endothelial cell (EC) repair. Methods: The efficacy of EPC-exosomes in re-endothelialization was examined by Evans Blue dye and histological examination in the rat model of balloon-induced carotid artery injury. The effects of EPC-exosomes on human vascular EC (HUVEC) were also studied by evaluating the effects on growth, migratory and tube formation. To dissect the underlying mechanism, RNA-sequencing assays were performed to determine miRNA abundance in exosomes and mRNA profiles in exosome-treated HUVECs. Meanwhile, in vitro loss of function assays identified an exosomal miRNA and its target gene in EC, which engaged in EPC-exosomes-induced EC repair. Results: Administration of EPC-exosomes potentiated re-endothelialization in the early phase after endothelial damage in the rat carotid artery. The uptake of exogenous EPC-exosomes intensified HUVEC in proliferation rate, migration and tube-forming ability. Integrative analyses of miRNA-mRNA interactions revealed that miR-21-5p was highly enriched in EPC-exosomes and specifically suppressed the expression of an angiogenesis inhibitor Thrombospondin-1 (THBS1) in the recipient EC. The following functional studies demonstrated a fundamental role of miR-21-5p in the pro-angiogenic activities of EPC-exosomes. Conclusions: The present work highlights a critical event for the regulation of EC behavior by EPC-exosomes, which EPC-exosomes may deliver miR-21-5p and inhibit THBS1 expression to promote EC repair.

Evaluation of endothelial progenitor cell (CD34) as a marker of cardiovascular risk in children on regular hemodialysis.

Endothelial progenitor cells (EPCs) CD34 are bone marrow-derived cells that decrease in chronic kidney disease (CKD) patients especially when they reach end-stage renal disease and may be a risk marker of cardiovascular (CV) diseases. The aim of our study is to investigate the endothelial progenitor cell CD 34 numbers in children with CKD on regular hemodialysis (HD) and detect their association with vascular stiffness. We recruited 25 children on regular HD, who were selected from the HD unit of Al-Zahraa Hospital, Al-Azhar University. Another group of 25 age and sex matched healthy children served as as controls. We investigated the number of EPC number (CD34) using flow cytometry, intima-media thickness (IMT), and the peak systolic velocity (PSV) of the main arteries including the (aorta, carotid, and femoral) arteries using Doppler ultrasound, this is in the same line with the routine and traditional investigations of the CV risk in the study groups. Children on regular HD have significantly lower EPC numbers (CD34 numbers) compared to their controls, the median and the inter equatorial range of CD34 was 57 (17-122) and five (3-6), respectively (P 0.001). Significant positive correlations were found between CD 34 and triglycerides serum level (r = 0.817, P = 0.001), also between CD34 with IMT and PSV of the aorta (r = 0.685, P = 0.000: r = 0.457, P = 0.022), respectively. CD34 is 88% sensitive and specific for the detection of CV risk in children on regular HD. EPC CD34 exhibited a higher predictive value for CV risk in children on regular HD. Reduced EPC numbers contribute to accelerated atherosclerosis.

[Investigation of the structure of a functionally intact xenopericardial bioconduit after long-term implantation]. / Issledovanie struktury funktsional'no sokhrannogo ksenoperikardial'nogo bioproteza posle prodolzhitel'nogo perioda implantatsii.

AIM: to investigate the cellular composition of a functionally intact xenopericardial valve in a recipient with acquired mitral defect after long-term implantation. MATERIAL AND METHODS: A Uniline bioconduit (BC) ('Neocor', Kemerovo) removed from the heart in the mitral position at 7.2 years after implantation was investigated. Heart valve leaflets were fixed in a buffered 4% paraformaldehyde solution and imbedded in paraffin or epoxy resin. Slices made from the paraffin samples were stained with hematoxylin and eosin or underwent immunohistochemical (IHC) examination for typing endothelial cells, smooth muscle cells, macrophages, fibroblasts, and T and B lymphocytes. The epoxy resin-embedded samples were examined using light and scanning electron microscopy according to the original procedure. For this, the samples were ground and polished, then stained with toluidine blue and basic fuchsin or contrasted with uranyl acetate and lead citrate. RESULTS: Different cell types were found in the outer layers of heart valve leaflets. IHC showed that endothelial cells, macrophages, smooth muscle cells, and fibroblasts were present in the samples. A relationship was found between the degree of degenerative changes in the BC surface and the magnitude of cellular infiltration in xenotissue. This paper debates whether impaired integrity of the surface leaflet layers plays a trigger role in structural dysfunctions of the implanted valves and whether BC endothelialization has a protective effect, which can considerably reduce the immunogenicity of xenotussie and prevent the penetration of recipient cells. CONCLUSION: The paper shows that it is expedient to modify the surface of the heart valve leaflets in order to create favorable conditions for the attachment and function of endothelial progenitor cells.

Soluble endothelial cell molecules and circulating endothelial cells in patients with venous thromboembolism.

: To evaluate the plasma levels of soluble endothelial cell molecules in patients with venous thromboembolism (VTE) out of the acute phase as compared with healthy individuals. We also investigated the possible associations of the soluble endothelial cell molecules among them, as well as with other clinical and laboratory data, including the numbers of circulating endothelial cells (CEC), circulating endothelial progenitor cells (CEP), and CEC expressing activation-related [cluster of differentiation (CD)54 and CD62E] and procoagulant (CD142) markers. In total, 15 patients with VTE and 20 normal individuals were studied. The CEC and CEP were quantified and characterized by flow cytometry. The soluble molecules studied included P-selectin, E-selectin, intercellular cell adhesion molecule 1, vascular cell adhesion molecule 1 and tissue factor (ELISA), and von Willebrand factor antigen (immunoturbidimetry). VTE patients had significantly higher levels of vascular cell adhesion molecule 1 and von Willebrand factor antigen and lower levels of soluble E-selectin than controls. They also showed significantly higher numbers of CEC, as of activated/procoagulant CEC and lower numbers of CEP, compared with controls. We did not find any correlation between the levels of soluble molecules and the numbers of endothelial cell in circulation, but there was with several clinical and laboratory data in VTE patients. Our results would suggest that in VTE patients, the endothelium remains activated and in some hypercoagulable state. The levels of soluble endothelial cell molecules did not seem to be directly related to the numbers of CEC and CEP neither reflected the number of activated CEC, which may be because of the different function that surface and soluble molecules may have.

Association between echocardiographic epicardial fat thickness and circulating endothelial progenitor cell level in patients with stable angina pectoris.

BACKGROUND: Epicardial adipose tissue is associated with coronary artery disease (CAD). Circulating endothelial progenitor cell (EPC) level represents a marker of endothelial dysfunction and vascular health. However, the relationship between epicardial fat and circulating EPC remains unknown. This study aimed to investigate association between echocardiographic epicardial fat thickness (EFT) and circulating EPC level. HYPOTHESIS: Epicardial fat causes inflammation and contributes to progression of CAD. METHODS: We enrolled 213 consecutive patients with stable angina, and EFT was determined by echocardiography. Quantification of EPC markers (defined as CD34 + , CD34 + KDR + , CD34 + KDR + CD133 + cells) in peripheral blood samples was used to measure circulating EPCs. All patients were divided into 3 tertiles according to EFT levels: group 1, low tertile of EFT; group 2, middle tertile of EFT; and group 3, high tertile of EFT. RESULTS: Among the 3 groups, CAD disease severity determined by SXscore was negatively correlated with EFT, but the difference did not reach statistical significance (P = 0.066). Additionally, patients in the high and middle tertiles of EFT had higher circulating EPC levels than did those in the low tertile of EFT (P = 0.001 and P < 0.001, respectively). In multivariate analysis, EPC level was significantly associated with echocardiographic EFT (standardized ß = -0.233, P = 0.001), independent of multiple covariates. CONCLUSIONS: Epicardial adipose tissue is associated with circulating EPC levels. There was a trend between epicardial fat and severity of CAD, though analysis did not reach statistical significance, and this may be attributed to the interaction between several risk factors of CAD.

Endothelial Progenitor Cells as Shuttle of Anticancer Agents.

Cell therapies are treatments in which stem or progenitor cells are stimulated to differentiate into specialized cells able to home to and repair damaged tissues. After their discovery, endothelial progenitor cells (EPCs) stimulated worldwide interest as possible vehicles to perform autologous cell therapy of tumors. Taking into account the tumor-homing properties of EPCs, two different approaches to control cancer progression have been pursued by combining cell-based therapy with gene therapy or with nanomedicine. The first approach is based on the possibility of engineering EPCs to express different transgenes, and the second is based on the capacity of EPCs to take up nanomaterials. Here we review the most important progress covering the following issues: the characterization of bona fide endothelial progenitor cells, their role in tumor vascularization and metastasis, and preclinical data about their use in cell-based tumor therapy, considering antiangiogenic, suicide, immune-stimulating, and oncolytic virus gene therapy. The mixed approach of EPC cell therapy and nanomedicine is discussed in terms of plasmonic-dependent thermoablation and molecular imaging.

Endothelial progenitor cells as a biological marker of peripheral artery disease.

The role of endothelial progenitor cells (EPCs) in peripheral artery disease (PAD) remains unclear. We hypothesized that EPC mobilization and function play a central role in the development of endothelial dysfunction and directly influence the degree of atherosclerotic burden in peripheral artery vessels. The number of circulating EPCs, defined as CD34(+)/KDR(+) cells, were assessed by flow cytometry in 91 subjects classified according to a predefined sample size of 31 non-diabetic PAD patients, 30 diabetic PAD patients, and 30 healthy volunteers. Both PAD groups had undergone endovascular treatment in the past. As a functional parameter, EPC colony-forming units were determined ex vivo. Apart from a broad laboratory analysis, a series of clinical measures using the ankle-brachial index (ABI), flow-mediated dilatation (FMD) and carotid intima-media thickness (cIMT) were investigated. A significant reduction of EPC counts and proliferation indices in both PAD groups compared to healthy subjects were observed. Low EPC number and pathological findings in the clinical assessment were strongly correlated to the group allocation. Multivariate statistical analysis revealed these findings to be independent predictors of disease appearance. Linear regression analysis showed the ABI to be a predictor of circulating EPC number (p=0.02). Moreover, the functionality of EPCs was correlated by linear regression (p=0.017) to cIMT. The influence of diabetes mellitus on EPCs in our study has to be considered marginal in already disease-affected patients. This study demonstrated that EPCs could predict the prevalence and severity of symptomatic PAD, with ABI as the determinant of the state of EPC populations in disease-affected groups.

Circulating endothelial progenitor cells are involved in VEGFR-2-related endothelial differentiation in glioma.

Endothelial progenitor cells (EPCs) play important roles in maintaining endothelial integrity and tumor vascularization. However, the differentiation of EPCs in the neoangiogenesis of gliomas has not yet been fully elucidated. The purpose in this study was to investigate the profile of EPC differentiation in rat C6 glioma using magnetic resonance imaging (MRI), a non-invasive monitoring assay. To achieve this goal, we isolated EPCs from rat bone marrow and identified them by detecting CD34, CD133, and VEGFR-2, the markers of EPCs. Coexpression of Ac-LDL and UEA-1 in EPCs was also determined. To dynamically monitor the migration of circulating cells, the EPCs were labeled with ultrasmall superparamagnetic iron oxide (USPIO) and injected by tail vein into rats bearing C6 glioma. MRI was performed at 24, 48, and 96 h after injection. The distribution and differentiation of EPCs were confirmed by histology. We found that the USPIO-labeled EPCs appeared at the tumor periphery where a large number of CD105-positive cells appeared at 24 h after injection by using MRI scanning. Ninety-six hours after injection, immunohistochemistry and Prussian blue staining were used to observe the labeled EPCs in the tumor tissue. We found that many of the labeled EPCs were overlapped with VEGFR-2-positive endothelial cells, but not CD105- or CD34-positive cells. These results suggest that EPCs can cross the blood-brain barrier from peripheral blood and home to tumors, where they differentiate into endothelial cells, including VEGFR-2-positive endothelial cells. MRI is a useful method for dynamically tracking the migration of USPIO-labeled EPCs.

Rapid synthesis of water-dispersible superparamagnetic iron oxide nanoparticles by a microwave-assisted route for safe labeling of endothelial progenitor cells.

We synthesize highly crystalline citrate-coated iron oxide superparamagnetic nanoparticles that are stable and readily dispersible in water by an extremely fast microwave-assisted route and investigate the uptake of magnetic nanoparticles by endothelial cells. Nanoparticles form large aggregates when added to complete endothelial cell medium. The size of the aggregates was controlled by adjusting the ionic strength of the medium. The internalization of nanoparticles into endothelial cells was then investigated by transmission electron microscopy, magnetometry and chemical analysis, together with cell viability assays. Interestingly, a sevenfold more efficient uptake was found for systems with larger nanoparticle aggregates, which also showed significantly higher magnetic resonance imaging effectiveness without compromising cell viability and functionality. We are thus presenting an example of a straightforward microwave synthesis of citrate-coated iron oxide nanoparticles for safe endothelial progenitor cell labeling and good magnetic resonance cell imaging with potential application for magnetic cell guidance and in vivo cell tracking.

Circulating hematopoietic progenitor cells are decreased in COPD.

RATIONALE: Bone marrow derived progenitor cells participate in the repair of injured vessels. The lungs of individuals with emphysema have reduced alveolar capillary density and increased endothelial apoptosis. We hypothesized that circulating levels of endothelial and hematopoietic progenitor cells would be reduced in this group of patients. OBJECTIVES: The goal of this study was to measure circulating levels of endothelial progenitor cells (EPCs) and hematopoietic progenitor cells (HPCs) in subjects with COPD and to determine if progenitor levels correlated with disease severity and the presence of emphysema. METHODS: Peripheral blood mononuclear cells were isolated from 61 patients with COPD and 32 control subjects. Levels of EPCs (CD45(dim) CD34+) and HPCs (CD45(+) CD34(+) VEGF-R2(+)) were quantified using multi-parameter flow cytometry. Progenitor cell function was assessed using cell culture assays. All subjects were evaluated with spirometry and CT scanning. MEASUREMENTS AND MAIN RESULTS: HPC levels were reduced in subjects with COPD compared to controls, whereas circulating EPC levels were similar between the two groups. HPC levels correlated with severity of obstruction and were lowest in subjects with severe emphysema. These associations remained after correction for factors known to affect progenitor cell levels including age, smoking status, the use of statin medications and the presence of coronary artery disease. The ability of mononuclear cells to form endothelial cell colony forming units (EC-CFU) was also reduced in subjects with COPD. CONCLUSIONS: HPC levels are reduced in subjects with COPD and correlate with emphysema phenotype and severity of obstruction. Reduction of HPCs may disrupt maintenance of the capillary endothelium, thereby contributing to the pathogenesis of COPD.