Potential Role of Caveolin-1 in Regulating the Function of Endothelial Progenitor Cells from Experimental MODS Model

Human Umbilical Vein Endothelial Cells as a Versatile Cellular Model System in Diverse Experimental Paradigms: An Ultrastructural Perspective

Human umbilical vein endothelial cells (HUVECs) are primary cells isolated from the vein of an umbilical cord, extensively used in cardiovascular studies and medical research. These cells, retaining the characteristics of endothelial cells in vivo, serve as a valuable cellular model system for understanding vascular biology, endothelial dysfunction, pathophysiology of diseases such as atherosclerosis, and responses to different drugs or treatments. Transmission electron microscopy (TEM) has been a cornerstone in revealing the detailed architecture of multiple cellular model systems including HUVECs, allowing researchers to visualize subcellular organelles, membrane structures, and cytoskeletal elements. Among them, the endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus can be meticulously examined to recognize alterations indicative of cellular responses to various stimuli. Importantly, Weibel-Palade bodies are characteristic secretory organelles found in HUVECs, which can be easily distinguished in the TEM. These distinctive structures also dynamically react to different factors through regulated exocytosis, resulting in complete or selective release of their contents. This detailed review summarizes the ultrastructural features of HUVECs and highlights the utility of TEM as a pivotal tool for analyzing HUVECs in diverse research frameworks, contributing valuable insights into the comprehension of HUVEC behavior and enriching our knowledge into the complexity of vascular biology.

Endothelial-Related Biomarkers in Evaluation of Vascular Function During Progression of Sepsis After Severe Trauma: New Potential Diagnostic Tools in Sepsis

Purpose

This study aimed to investigate the changes in endothelial-related biomarkers and their relationship with the incidence and prognosis of patients with sepsis after severe trauma.

Methods

A total of 37 severe trauma patients admitted to our hospital from Jan. to Dec. 2020 were enrolled in our research. All enrolled patients were divided into the sepsis and the non-sepsis groups. Endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and endothelial microparticles (EMPs) were detected on admission time; 24-48 hours and 48-72 hours after admission respectively. Demographic data, Acute Physiology, Chronic Health Evaluation (APACHE) II, and Sequential Organ Failure Assessment (SOFA) score were calculated every 24 h of admission to assess the severity of organ dysfunction. Receiver operating characteristic (ROC) curves were drawn to compare the areas under the curve (AUC) of endothelial-related biomarkers for the diagnosis of sepsis.

Results

The incidence rate of sepsis was 45.95% in all patients. The SOFA score in the sepsis group was significantly higher than that in the non-sepsis group (2 points vs 0 points, P<0.01). The number of EPCs, CECs, and EMPs all rose quickly in the early phase after trauma. The number of EPCs was similar in both groups, but the number of CECs and EMPs in the Sepsis Group was much higher than in the non-Sepsis Group (all P<0.01). Logistic regression analysis showed that the occurrence of sepsis was closely related to the expression of 0-24h CECs and 0-24h EMPs. The AUC ROC for CECs in different time periods were 0.815, 0.877, and 0.882, respectively (all P<0.001). The AUC ROC for EMPs in 0-24h was 0.868 (P=0.005).

Conclusion

The expression of EMPs was higher in early severe trauma, and high levels of EMPs were significantly higher in patients with early sepsis and poor prognosis.

Rabbit Endothelial Progenitor Cells Derived From Peripheral Blood and Bone Marrow: An Ultrastructural Comparative Study

The present study was designed to compare the ultrastructure of early endothelial progenitor cells (EPCs) derived from rabbit peripheral blood (PB-EPCs) and bone marrow (BM-EPCs). After the cells had been isolated and cultivated up to passage 3, microphotographs obtained from transmission electron microscope were evaluated from qualitative and quantitative (unbiased stereological approaches) points of view. Our results revealed that both cell populations displayed almost identical ultrastructural characteristics represented by abundant cellular organelles dispersed in the cytoplasm. Moreover, the presence of very occasionally occurring mature endothelial-specific Weibel–Palade bodies (WPBs) confirmed their endothelial lineage origin. The more advanced stage of their differentiation was also demonstrated by the relatively low nucleus/cytoplasm (N/C) ratios (0.41 ± 0.19 in PB-EPCs; 0.37 ± 0.25 in BM-EPCs). Between PB-EPCs and BM-EPCs, no differences in proportions of cells occupied by nucleus (28.13 ± 8.97 versus 25.10 ± 11.48%), mitochondria (3.71 ± 1.33 versus 4.23 ± 1.00%), and lipid droplets (0.65 ± 1.01 versus 0.36 ± 0.40%), as well as in estimations of the organelles surface densities were found. The data provide the first quantitative evaluation of the organelles of interest in PB-EPCs and BM-EPCs, and they can serve as a research framework for understanding cellular function.

Aerobic and resistance training enhances endothelial progenitor cell function via upregulation of caveolin-1 in mice with type 2 diabetes

Background

To explore the effect of aerobic training (AT), resistance training (RT) or a combination of AT and RT (AT+RT) on the function of endothelial progenitor cells (EPCs) in mice with type 2 diabetes and the potential effective mechanisms

Methods

Eight-week-old db/db male mice were used as type 2 diabetic animal models in this study. Mice were randomly assigned to the control group (n = 5), AT group (n = 5), RT group (n = 5) and AT+RT group (n = 5). Mice in the control group remained sedentary with no specific training requirement. Mice were motivated to perform AT, RT or AT+RT by a gentle pat on their body for 3 or 4 days/week for 14 days. AT was performed by treadmill running, RT was performed by ladder climbing and AT+RT involved both AT and RT. Bone-derived EPCs were isolated after 14 days of the intervention. EPC expression of CD31, CD34, CD133, CD144 and VEGFR2 was detected by immunofluorescence staining. Fluorescence detection was performed on attached mononuclear cells to detect double-positive EPCs. We then explored the effect of caveolin-1 knockdown (lentiviral vector with caveolin-1-siRNA) on the proliferation and adherence of EPCs and the concentration of caveolin-1 and PI3K/AKT via western blot analyses.

Results

Compared to the mice in the control group, the mice in the AT, RT and AT+RT groups presented significant increases in proliferation and adherence after 14 days of intervention. AT+RT induced an increase in EPC adherence, which was greater than that of the control, RT and AT groups. Caveolin-1 knockdown inhibited the EPC proliferative and adherent abilities. The AT+RT group showed higher levels of caveolin-1 and p-AKT than the control group, but these changes were decreased by caveolin-1-siRNA transfection.

Conclusion

Combined AT and RT is an effective way to improve EPC function through upregulation of caveolin-1 in mice with type 2 diabetes.