Isolation and characterization of endothelial progenitor cells from canine bone marrow

The mechanisms and applications of endothelial progenitor cell therapy in the treatment of intracranial aneurysm

The pathophysiological mechanism of intracranial aneurysm (IA) involves the dynamic interaction of ECM abnormalities, hemodynamic stress, and inflammatory response. The rupture of intracranial aneurysm will cause serious consequences. Multiple studies have confirmed the important role and potential application of endothelial progenitor cells (EPCs) in vascular repair. This review focuses on the specific mechanism of EPCs in the treatment of intracranial aneurysms, which promote re-endothelialization and angiogenesis through bone marrow mobilization, targeted migration to the site of injury, differentiation into mature endothelial cells, and secretion of angiogenic factors. In addition, EPCs maintain ECM homeostasis by regulating MMP/IMP balance, inhibiting aneurysm wall thinning and structural damage. Based on the vascular repair mechanism of EPCs, new treatment strategies such as "biologically active" spring coils (loaded with EPCs or SDF-1α) and flow diverters(FDs) combined with EPCs therapy have been developed to synergistically promote carotid endothelialization of aneurysms and reduce the risk of recurrence. Future research needs to further validate the long-term efficacy and precise regulatory mechanisms of EPCs in clinical translation, providing new directions for IA treatment.

Endothelial characteristics of cardiac stem cell antigen-1 expressing cells and their relevance to right ventricular adaptation

A growing body of evidence suggest that the stem cell antigen-1 expressing (Sca-1+) cells in the heart may be the cardiac endothelial stem/progenitor cells. Their endothelial cell (EC) functions, and their role in right ventricle (RV) physiology and pathophysiology of right heart failure (RHF) remains poorly defined. This study investigated EC characteristics of rat cardiac Sca-1+ cells, assessed spatial distribution and studied changes in Sca-1+ cells during RV remodelling in monocrotaline (MCT) model of pulmonary hypertension and RV remodeling. First, flow-cytometry analysis of adult male and female Sprague Dawley (SD) and Fischer CDF rat heart cells was performed, and we observed that the majority of Sca-1+ cells also expressed CD31, an EC marker. Furthermore, Sca-1+ cells showed acetylated low-density lipoprotein (ac-LDL) uptake and lectin binding similar to CD31+ cells from the same heart. The Sca-1+ cells also demonstrated network formation when plated on Matrigel. In the MCT treated rats, we observed increase in RV hypertrophy that correlated with the reduction in the abundance of Sca-1+CD31+ cells in the RV. Together, the cardiac Sca-1+ cells in the heart are endothelial stem/progenitor-like cells. These cells have higher abundance in the RV and may play a role in RV adaptation.

Endothelial progenitor cells for fabrication of engineered vascular units and angiogenesis induction

The promotion of vascularization and angiogenesis in the grafts is a crucial phenomenon in the healing process and tissue engineering. It has been shown that stem cells, especially endothelial progenitor cells (EPCs), can stimulate blood vessel formation inside the engineered hydrogels after being transplanted into the target sites. The incorporation of EPCs into the hydrogel can last the retention time, long-term survival, on-target delivery effects, migration and differentiation into mature endothelial cells. Despite these advantages, further modifications are mandatory to increase the dynamic growth and angiogenesis potential of EPCs in in vitro and in vivo conditions. Chemical modifications of distinct composites with distinct physical properties can yield better regenerative potential and angiogenesis during several pathologies. Here, we aimed to collect recent findings related to the application of EPCs in engineered vascular grafts and/or hydrogels for improving vascularization in the grafts. Data from the present article can help us in the application of EPCs as valid cell sources in the tissue engineering of several ischemic tissues.

Endothelial progenitor cells in pregnancy-related diseases

Placental neovascularization plays a crucial role in fetomaternal circulation throughout pregnancy and is dysregulated in several pregnancy-related diseases, including preeclampsia, gestational diabetes mellitus, and fetal growth restriction. Endothelial progenitor cells (EPCs) are a heterogeneous population of cells that differentiate into mature endothelial cells, which influence vascular homeostasis, neovascularization, and endothelial repair. Since their discovery in 1997 by Asahara et al., the role of EPCs in vascular biology has garnered a lot of interest. However, although pregnancy-related conditions are associated with changes in the number and function of EPCs, the reported findings are conflicting. This review discusses the discovery, isolation, and classification of EPCs and highlights discrepancies between current studies. Overviews of how various diseases affect the numbers and functions of EPCs, the role of EPCs as biomarkers of pregnancy disorders, and the potential therapeutic applications involving EPCs are also provided.

Endothelial progenitor cell-derived exosomes promote anti-inflammatory macrophages via SOCS3/JAK2/STAT3 axis and improve the outcome of spinal cord injury

BACKGROUND

Macrophage in the spinal cord injury (SCI) area imparts a chronic pro-inflammation effect that challenges the recovery of SCI. Previously, endothelial progenitor cell-produced exosomes (EPC-EXOs) have been noticed to facilitate revascularization and inflammation control after SCI. However, their effects on macrophage polarization remained unclear. This study aimed to investigate the EPC-EXOs' role in macrophage polarization and reveal its underlying mechanism.

METHODS

We extracted the macrophages and EPC from the bone marrow suspension of C57BL/L mice by centrifugation. After cell identification, the EPC-EXOs were collected by ultra-high-speed centrifugation and exosome extraction kits and identified by transmission electron microscopy and nanoparticle tracking analysis. Then, macrophages were cultured with EPC-EXOs in different concentrations. We labeled the exosome to confirm its internalization by macrophage and detected the macrophage polarization marker level both in vitro and in vivo. We further estimated EPC-EXOs' protective effects on SCI by mice spinal cord tissue H&E staining and motor behavior evaluation. Finally, we performed RT-qPCR to identify the upregulated miRNA in EPC-EXOs and manipulate its expression to estimate its role in macrophage polarization, SOCS3/JAK2/STAT3 pathway activation, and motor behavior improvement.

RESULTS

We found that EPC-EXOs decreased the macrophages' pro-inflammatory marker expression and increased their anti-inflammatory marker expression on the 7 and 14 days after SCI. The spinal cord H&E staining results showed that EPC-EXOs raised the tissue-sparing area rate significantly after 28 days of SCI and the motor behavior evaluation indicated an increased BMS score and motor-evoked potential by EPC-EXOs treatment after SCI. The RT-qPCR assay identified that miR-222-3P upregulated in EPC-EXOs and its miRNA-mimic also decreased the pro-inflammatory macrophages and increased the anti-inflammatory macrophages. Additionally, miR-222-3P mimic activated the SOCS3/JAK2/STAT3 pathway, and SOCS3/JAK2/STAT3 pathway inhibition blocked miR-2223P's effects on macrophage polarization and mouse motor behavior.

CONCLUSION

Comprehensively, we discovered that EPC-EXOs-derived miR-222-3p affected macrophage polarization via SOCS3/JAK2/STAT3 pathway and promoted mouse functional repair after SCI, which reveals EPC-EXOs' role in modulation of macrophage phenotype and will provide a novel interventional strategy to induce post-SCI recovery.

Detection of Circulating Tumor Cells and Epithelial Progenitor Cells: A Comprehensive Study

Technological advancement to enhance tumor cells (TC) has allowed discovery of various cellular bio-markers: cancer stem cells (CSC), circulating tumor cells (CTC), and endothelial progenitor cells (EPC). These are responsible for resistance, metastasis, and premetastatic conditions of cancer. Detection of CSC, CTC, and EPC assists in early diagnosis, recurrence prediction, and treatment efficacy. This review describes various methods to detect TC subpopulations such as in vivo assays (sphere-forming, serial dilution, and serial transplantation), in vitro assays (colony-forming cells, microsphere, side-population, surface antigen staining, aldehyde dehydrogenase activity, and Paul Karl Horan label-retaining cells, surface markers, nonenriched and enriched detection), reporter systems, and other analytical methods (flow cytometry, fluorescence microscopy/spectroscopy, etc.). The detailed information on methods to detect CSC, CTC, and EPC in this review will assist investigators in successful prognosis, diagnosis, and cancer treatment with greater ease.

Intervention effects of traditional Chinese medicine on stem cell therapy of myocardial infarction

Cardiovascular diseases are the leading cause of global mortality, in which myocardial infarction accounts for 46% of total deaths. Although good progress has been achieved in medication and interventional techniques, a proven method to repair the damaged myocardium has not yet been determined. Stem cell therapy for damaged myocardial repair has evolved into a promising treatment for ischemic heart disease. However, low retention and poor survival of the injected stem cells are the major obstacles to achieving the intended therapeutic effects. Chinese botanical and other natural drug substances are a rich source of effective treatment for various diseases. As such, numerous studies have revealed the role of Chinese medicine in stem cell therapy for myocardial infarction treatment, including promoting proliferation, survival, migration, angiogenesis, and differentiation of stem cells. Here, we discuss the potential and limitations of stem cell therapy, as well as the regulatory mechanism of Chinese medicines underlying stem cell therapy. We focus on the evidence from pre-clinical trials and clinical practices, and based on traditional Chinese medicine theories, we further summarize the mechanisms of Chinese medicine treatment in stem cell therapy by the commonly used prescriptions. Despite the pre-clinical evidence showing that traditional Chinese medicine is helpful in stem cell therapy, there are still some limitations of traditional Chinese medicine therapy. We also systematically assess the detailed experimental design and reliability of included pharmacological research in our review. Strictly controlled animal models with multi-perspective pharmacokinetic profiles and high-grade clinical evidence with multi-disciplinary efforts are highly demanded in the future.

An Update on Molecular Pathways Regulating Vasculogenic Mimicry in Human Osteosarcoma and Their Role in Canine Oncology

Canine tumors are valuable comparative models for human counterparts, especially to explore novel biomarkers and to understand pathways and processes involved in metastasis. Vasculogenic mimicry (VM) is a unique property of malignant cancer cells which promote metastasis. Thus, it represents an opportunity to investigate both the molecular mechanisms and the therapeutic targets of a crucial phenotypic malignant switch. Although this biological process has been largely investigated in different human cancer types, including osteosarcoma, it is still largely unknown in veterinary pathology, where it has been mainly explored in canine mammary tumors. The presence of VM in human osteosarcoma is associated with poor clinical outcome, reduced patient survival, and increased risk of metastasis and it shares the main pathways involved in other type of human tumors. This review illustrates the main findings concerning the VM process in human osteosarcoma, search for the related current knowledge in canine pathology and oncology, and potential involvement of multiple pathways in VM formation, in order to provide a basis for future investigations on VM in canine tumors.

Panax notoginseng saponins promote endothelial progenitor cell angiogenesis via the Wnt/β-catenin pathway

Background

Distraction osteogenesis (DO) is an effective treatment in craniomaxillofacial surgery. However, the issue of sufficient blood supply at the regeneration tissue has limited its wide application. Panax notoginseng saponins (PNS) is a Traditional Chinese Medicine that is commonly used to treat a range of angiogenic diseases. However, the mechanisms whereby PNS alters angiogenesis in endothelial progenitor cells (EPCs) have yet to be clarified.

Methods

EPCs were identified by immunofluorescence, confirmed by their uptake of fluorescently labeled Dil-ac-LDL and FITC-UEA-1. EPCs were treated with different concentrations of PNS, and the effects of PNS on cell proliferation were measured on the optimal concentration of PNS determined. The effects of PNS on angiogenesis and migration, angiogenic cytokines mRNA expression and the proteins of the Wnt pathway were investigated. Then knocked down β-catenin in EPCs and treated with the optimum concentrational PNS, their angiogenic potential was evaluated in tube formation and migration assays. In addition, the expression of cytokines associated with angiogenesis and Wnt/β-catenin was then assessed via WB and RT-qPCR.

Results

We were able to determine the optimal concentration of PNS in the promotion of cell proliferation, tube formation, and migration to be 6.25 mg/L. PNS treatment increased the mRNA levels of VEGF, bFGF, VE-Cadherin, WNT3a, LRP5, β-catenin, and TCF4. After knocked down β-catenin expression, we found that PNS could sufficient to partially reverse the suppression of EPC angiogenesis.

Conclusions

Overall, 6.25 mg/L PNS can promote EPC angiogenesis via Wnt/β-catenin signaling pathway activation.

Experimental Study on the Effect of Allogeneic Endothelial Progenitor Cells on Wound Healing in Diabetic Mice

Endothelial progenitor cells (EPCs) are involved in the neovascularization in traumatic and ischemic sites, but EPCs are "detained" in bone marrow under diabetic conditions, which results in reduction of the number of EPCs and their biological activity in peripheral blood. Based on our previous study to mobilize autologous bone marrow EPCs by administering AMD3100+G-CSF to realize the optimal effect, our present study is aimed at exploring the effects of transplanting EPCs locally in a wound model of diabetic mice. First, we prepared and identified EPCs, and the biological functions and molecular characteristics were compared between EPCs from DB/+ and DB/DB mice. Then, we performed full-thickness skin resection in DB/DB mice and tested the effect of local transplantation of EPCs on skin wound healing. The wound healing process was recorded using digital photographs. The animals were sacrificed on postoperative days 7, 14, and 17 for histological and molecular analysis. Our results showed that DB/+ EPCs were biologically more active than those of DB/DB EPCs. When compared with the control group, local transplantation of EPCs accelerated wound healing in DB/DB mice by promoting wound granulation tissue formation, angiogenesis, and collagen fiber deposition, but there was no significant difference in wound healing between DB/+ EPCs and DB/DB EPCs transplanted into the wound. Furthermore, local transplantation of EPCs promoted the expression of SDF-1, CXCR4, and VEGF. We speculated that EPC transplantation may promote wound healing through the SDF-1/CXCR4 axis. This point is worth exploring further. Present data are of considerable significance because they raise the possibility of promoting wound healing by isolating autologous EPCs from the patient, which provides a new approach for the clinical treatment of diabetic wounds in the future.