Circulating Progenitor Cells after Cold Pressor Test in Hypertensive and Uremic Patients

Understanding Vascular Calcification in Chronic Kidney Disease: Pathogenesis and Therapeutic Implications

Vascular calcification (VC) is a biological phenomenon characterized by an accumulation of calcium and phosphate deposits within the walls of blood vessels causing the loss of elasticity of the arterial walls. VC plays a crucial role in the incidence and progression of chronic kidney disease (CKD), leading to a significant increase in cardiovascular mortality in these patients. Different conditions such as age, sex, dyslipidemia, diabetes, and hypertension are the main risk factors in patients affected by chronic kidney disease. However, VC may occur earlier and faster in these patients if it is associated with new or non-traditional risk factors such as oxidative stress, anemia, and inflammation. In chronic kidney disease, several pathophysiological processes contribute to vascular calcifications, including osteochondrogenic differentiation of vascular cells, hyperphosphatemia and hypercalcemia, and the loss of specific vascular calcification inhibitors including pyrophosphate, fetuin-A, osteoprotegerin, and matrix GLA protein. In this review we discuss the main traditional and non-traditional risk factors that can promote VC in patients with kidney disease. In addition, we provide an overview of the main pathogenetic mechanisms responsible for VC that may be crucial to identify new prevention strategies and possible new therapeutic approaches to reduce cardiovascular risk in patients with kidney disease.

Predictors, prevalence and prognostic role of pulmonary hypertension in patients with chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

To estimate the predictors, prevalence and prognostic role of pulmonary hypertension (PH) in patients with chronic kidney disease (CKD) using meta-analysis.

METHODS

The PubMed, EmBase, and the Cochrane library were systematically searched for eligible studies from inception till May 2024. All of pooled analyses were performed using the random-effects model.

RESULTS

Fifty observational studies involving 17,558 CKD patients were selected. The prevalence of PH in CKD patients was 38% (95% confidence interval [CI]: 33%-43%), and the prevalence according to CKD status were 31% (95% CI: 20%-42%) for CKD (I-V), 39% (95% CI: 25%-54%) for end stage kidney disease (ESKD) (predialysis), 42% (95% CI: 35%-50%) for ESKD (hemodialysis), and 26% (95% CI: 19%-34%) for renal transplant. We noted the risk factors for PH in CKD included Black individuals (relative risk [RR]: 1.39; 95% CI: 1.18-1.63; p < 0.001), chronic obstructive pulmonary disease (RR: 1.48; 95% CI: 1.21-1.82; p < 0.001), cardiovascular disease history (RR: 1.62; 95% CI: 1.05-2.51; p = 0.030), longer dialysis (RR: 1.70; 95% CI: 1.18-2.46; p = 0.005), diastolic dysfunction (RR: 1.88; 95% CI: 1.38-2.55; p < 0.001), systolic dysfunction (RR: 3.75; 95% CI: 2.88-4.87; p < 0.001), and grade 5 CKD (RR: 5.64; 95% CI: 3.18-9.98; p < 0.001). Moreover, PH in CKD patients is also associated with poor prognosis, including all-cause mortality, major cardiovascular events, and cardiac death.

CONCLUSION

This study systematically identified risk factors for PH in CKD patients, and PH were associated with poor prognosis. Therefore, patients with high prevalence of PH should be identified for treatment.

Selenoprotein-P1 (SEPP1) Expression in Human Proximal Tubule Cells after Ischemia-Reperfusion Injury: An In Vitro Model

Background and Objectives: Selenium deficiency represents a risk factor for the occurrence of severe diseases, such as acute kidney injury (AKI). Recently, selenoprotein-p1 (SEPP1), a selenium transporter, mainly released by the liver, has emerged as a promising plasmatic biomarker of AKI as a consequence of cardio-surgery operations. The aim of the present study was to investigate, on an in vitro model of hypoxia induced in renal tubular cells, HK-2, the effects of sodium selenite (Na2SeO3) and to evaluate the expression of SEPP1 as a marker of injury. Materials and Methods: HK-2 cells were pre-incubated with 100 nM Na2SeO3 for 24 h, and then, treated for 24 h with CoCl2 (500 µM), a chemical hypoxia inducer. The results were derived from an ROS assay, MTT, and Western blot analysis. Results: The pre-treatment determined an increase in cells' viability and a reduction in reactive oxygen species (ROS), as shown by MTT and the ROS assay. Moreover, by Western blot an increase in SEPP1 expression was observed after hypoxic injury as after adding sodium selenite. Conclusions: Our preliminary results shed light on the possible role of selenium supplementation as a means to prevent oxidative damage and to increase SEPP1 after acute kidney injury. In our in vitro model, SEPP1 emerges as a promising biomarker of kidney injury, although further studies in vivo are necessary to validate our findings.

Patient Endothelial Colony-Forming Cells to Model Coronary Artery Disease Susceptibility and Unravel the Role of Dysregulated Mitochondrial Redox Signalling

Mechanisms involved in the individual susceptibility to atherosclerotic coronary artery disease (CAD) beyond traditional risk factors are poorly understood. Here, we describe the utility of cultured patient-derived endothelial colony-forming cells (ECFCs) in examining novel mechanisms of CAD susceptibility, particularly the role of dysregulated redox signalling. ECFCs were selectively cultured from peripheral blood mononuclear cells from 828 patients from the BioHEART-CT cohort, each with corresponding demographic, clinical and CT coronary angiographic imaging data. Spontaneous growth occurred in 178 (21.5%) patients and was more common in patients with hypertension (OR 1.45 (95% CI 1.03-2.02), p = 0.031), and less likely in patients with obesity (OR 0.62 [95% CI 0.40-0.95], p = 0.027) or obstructive CAD (stenosis > 50%) (OR 0.60 [95% CI 0.38-0.95], p = 0.027). ECFCs from patients with CAD had higher mitochondrial production of superoxide (O₂^--MitoSOX assay). The latter was strongly correlated with the severity of CAD as measured by either coronary artery calcium score (R² = 0.46; p = 0.0051) or Gensini Score (R² = 0.67; p = 0.0002). Patient-derived ECFCs were successfully cultured in 3D culture pulsatile mini-vessels. Patient-derived ECFCs can provide a novel resource for discovering mechanisms of CAD disease susceptibility, particularly in relation to mitochondrial redox signalling.

Nephrosclerosis impacts time trajectory of renal function and outcomes in elderly individuals with chronic kidney disease

Despite hypertension ranks among the leading causes of chronic kidney disease (CKD), the impact of chronic hypertensive nephropathy, the so-called 'nephrosclerosis' (NS), on CKD progression is often unpredictable, particularly in elderly population. We have conducted a prospective, observational study to define renal function patterns and outcomes in elderly CKD individuals with or without NS. Three hundred four individuals with an already established CKD were categorized according to the etiology of CKD. NS was defined as the presence of CKD associated with long-term essential hypertension, hypertensive retinopathy, left ventricular hypertrophy and minimal proteinuria. Time trajectories in estimated glomerular filtration rate (eGFR) (CKD-Epi) were computed over a 4-year follow-up. In addition, we analyzed the occurrence of a composite outcome of doubling of serum creatinine levels, eGFR reduction ≥25% and/or the need of chronic renal replacement therapy. CKD was secondary to nephrosclerosis (CKD-NS) in 220 (72.3%). In the whole cohort, the average estimated annual GFR slope was 1.8 mL/min/1.73 m² eGFR decline was slower in CKD-NS as compared with others (1.4 vs 3.4 mL/min/1.73 m²; p<0.001). The composite renal outcome during follow-up occurred less frequently among elderly with CKD-NS (16/204 vs 14/70; p=0.01, crude HR 0.43, 95% CI 0.22 to 0.85) and was associated at logistic analyses with the etiology of CKD, background cardiovascular disease, total and low density lipoproteins (LDL) cholesterol, and glycemia levels (p value was ranging from 0.01 to 0.05). Despite being highly prevalent in the elderly, NS is associated with a more favorable renal disease course as compared with other conditions.

Maternal peripheral blood CD34+ cells for prediction of fetal kidney malformations: results from a case-control analysis

PURPOSE

To evaluate the relation between CD34+ cells count in maternal blood and potential development of fetal congenital renal abnormalities.

MATERIALS AND METHODS

We enrolled 16 women that gave birth to newborns carrying congenital renal malformations over a 3-year period and 48 women with uncomplicated pregnancies (controls) in a 1:3 ratio (three controls per case).

RESULTS

CD34+ cells in the maternal peripheral blood were significantly lower in the group of women who gave birth to newborns carrying congenital renal malformations compared to the controls (p < .0001).

CONCLUSIONS

CD34+ cells in maternal blood could be validated as a potential marker to predict the development of possible kidney malformations.

Sesn2 attenuates the damage of endothelial progenitor cells induced by angiotensin II through regulating the Keap1/Nrf2 signal pathway

Endothelial progenitor cell (EPC) dysfunction is an important physiopathological mechanism in the dynamics of the formation of atherosclerosis. It has been reported that angiotensin II (Ang-II) damages the function of EPCs in atherosclerotic plaque through induction of oxidative stress. Sestrin 2 (Sesn2) serves as an antioxidant role in oxidative stress, however, the exact mechanisms underlying the dynamics of how Sesn2 may factor into EPCs after Ang-II treatments needs to be illustrated. We isolated EPCs from human umbilical cord blood samples and treated with Ang-II. Western blotting, qRT-PCR, transwell assays, immunofluorescence and so on were used to investigate the mechanisms underlying the roles of Sesn2 in EPCs treated with Ang-II. Ang-II was found to promote the apoptosis of EPCs as well as inhibited the mRNA and protein expression of Sesn2. Upregulation of Sesn2 attenuated the negative effect of Ang-II. Sesn2 increased the protein expression of Nrf2 by enhancing P62-dependent autophagy. Silencing of Nrf2 enhanced the degree of apoptosis of EPCs as well as resulted in the impairment of EPC functions through inducing the promotion of (reactive oxygen species) ROS production. Our study results indicated that Sesn2 facilitated the viability of EPCs After treatment with Ang-II, as well as provided a potential therapeutic target to alleviate the progression of atherosclerosis.

Erythropoiesis and chronic kidney disease-related anemia: From physiology to new therapeutic advancements

Erythropoiesis is triggered by hypoxia and is strictly regulated by hormones, growth factors, cytokines, and vitamins to ensure an adequate oxygen delivery to all body cells. Abnormalities in one or more of these factors may induce different kinds of anemia requiring different treatments. A key player in red blood cell production is erythropoietin. It is a glycoprotein hormone, mainly produced by the kidneys, that promotes erythroid progenitor cell survival and differentiation in the bone marrow and regulates iron metabolism. A deficit in erythropoietin synthesis is the main cause of the normochromic normocytic anemia frequently observed in patients with progressive chronic kidney disease. The present review summarizes the most recent findings about each step of the erythropoietic process, going from the renal oxygen sensing system to the cascade of events induced by erythropoietin through its own receptor in the bone marrow. The paper also describes the new class of drugs designed to stabilize the hypoxia-inducible factor by inhibiting prolyl hydroxylase, with a discussion about their metabolism, disposition, efficacy, and safety. According to many trials, these drugs seem able to simulate tissue hypoxia and then stimulate erythropoiesis in patients affected by renal impairment. In conclusion, the in-depth investigation of all events involved in erythropoiesis is crucial to understand anemia pathophysiology and to identify new therapeutic strategies, in an attempt to overcome the potential side effects of the commonly used erythropoiesis-stimulating agents.

Endothelial progenitor cells and hypertension: current concepts and future implications

The discovery of endothelial progenitor cells (EPCs), a group of cells that play important roles in angiogenesis and the maintenance of vascular endothelial integrity, has led to considerable improvements in our understanding of the circulatory system and the regulatory mechanisms of vascular homoeostasis. Despite lingering disputes over where EPCs actually originate and how they facilitate angiogenesis, extensive research in the past decade has brought about significant advancements in this field of research, establishing EPCs as an essential element in the pathogenesis of various diseases. EPC and hypertensive disorders, especially essential hypertension (EH, also known as primary hypertension), represent one of the most appealing branches in this area of research. Chronic hypertension remains a major threat to public health, and the exact pathologic mechanisms of EH have never been fully elucidated. Is there a relationship between EPC and hypertension? If so, what is the nature of such relationship-is it mediated by blood pressure alterations, or other factors that lie in between? How can our current knowledge about EPCs be utilized to advance the prevention and clinical management of hypertension? In this review, we set out to answer these questions by summarizing the current concepts about EPC pathophysiology in the context of hypertension, while attempting to point out directions for future research on this subject.

The effect of diabetes mellitus and end-stage renal disease on the number of CD34+ cells in the blood

The aim of this study was to investigate the effect of end-stage renal disease (ESRD) and diabetes mellitus (DM) on the number of stem cells in the peripheral blood. Sixty-two patients diagnosed with ESRD who had not received dialysis previously, 25 patients with a diagnosis of DM without nephropathy, and 21 healthy volunteers were included in the study. The group diagnosed with ESRD was divided into two groups. The first group (DM-CRD) consisted of 28 patients with DM who had developed chronic renal disease (CRD). The second group (NON-DM-CRD) consisted of 34 patients without DM who had CRD by etiology. The routine complete blood count, renal function, and number of CD34+ cells were determined for all of those involved in the study. The microalbumin/creatinine levels were measured, and glomerular filtration rates were calculated in all patients. The number of CD34+ cells was found to be significantly lower in the DM control group and DM-CRD group compared with the healthy group. No statistically significant difference was found between the NON-DM-CRD and the healthy control group. There was a moderate negative correlation between the ratio of microalbumin/creatinine and the number of CD34+ cells. A significant reduction in the number of CD34+ cells was shown in subjects with DM and ESRD caused by diabetic nephropathy.

Circulating endothelial progenitor cells in kidney transplant patients

BACKGROUND

Kidney transplantation (RTx) leads to amelioration of endothelial function in patients with advanced renal failure. Endothelial progenitor cells (EPCs) may play a key role in this repair process. The aim of this study was to determine the impact of RTx and immunosuppressive therapy on the number of circulating EPCs.

METHODS

We analyzed 52 RTx patients (58±13 years; 33 males, mean ± SD) and 16 age- and gender-matched subjects with normal kidney function (57±17; 10 males). RTx patients received a calcineurin inhibitor (CNI)-based (65%) or a CNI-free therapy (35%) and steroids. EPC number was determined by double positive staining for CD133/VEGFR2 and CD34/VEGFR2 by flow cytometry. Stromal cell-derived factor 1 alpha (SDF-1) levels were assessed by ELISA. Experimentally, to dissociate the impact of RTx from the impact of immunosuppressants, we used the 5/6 nephrectomy model. The animals were treated with a CNI-based or a CNI-free therapy, and EPCs (Sca+cKit+) and CD26+ cells were determined by flow cytometry.

RESULTS

Compared to controls, circulating number of CD34+/VEGFR2+ and CD133+/VEGFR2+ EPCs increased in RTx patients. There were no correlations between EPC levels and statin, erythropoietin or use of renin angiotensin system blockers in our study. Indeed, multivariate analysis showed that SDF-1--a cytokine responsible for EPC mobilization--is independently associated with the EPC number. 5/6 rats presented decreased EPC counts in comparison to control animals. Immunosuppressive therapy was able to restore normal EPC values in 5/6 rats. These effects on EPC number were associated with reduced number of CD26+ cells, which might be related to consequent accumulation of SDF-1.

CONCLUSIONS

We conclude that kidney transplantation and its associated use of immunosuppressive drugs increases the number of circulating EPCs via the manipulation of the CD26/SDF-1 axis. Increased EPC count may be associated to endothelial repair and function in these patients.

Mechanisms and significance of progenitor cell reduction in the metabolic syndrome

Bone marrow-derived progenitor cells are involved in the homeostasis of the cardiovascular system through differentiation into endothelium, smooth muscle, and cardiomyocytes. Alterations of these extremely plastic cells have been recognized as both markers of cardiovascular risk and pathophysiological links between risk factors and development of atherosclerosis. Metabolic syndrome, as a cluster of well-defined cardiovascular risk factors, represents a strong predictor of cardiovascular events and death. Moreover, components of the syndrome interact with one another and synergistically increase this risk. Here we describe all metabolic syndrome components as being characterized by alterations in circulating progenitor cells, especially endothelial cells. We also highlight how endothelial progenitors may mediate the interactions between cardiometabolic risk factors in a complex interplay and discuss potential implications for prevention and therapy.

Endothelial progenitor cell dysfunction in patients with progressive chronic kidney disease

Endothelial progenitor cells (EPC) contribute to repair and maintenance of the vascular system, but in patients with chronic kidney disease (CKD), the number and function of EPC may be affected by kidney dysfunction. We assessed numbers and the angiogenic function of EPC from patients with CKD in relation to disease progression. In a cross-sectional, prospective study, 50 patients with varying degrees of CKD, including 20 patients undergoing dialysis and 10 healthy controls, were included. Mononuclear cells were isolated, and circulating EPC were quantified by flow cytometry based on expression of CD14 and CD34. EPC were cultured on fibronectin-coated supramolecular films of oligocaprolactone under angiogenic conditions to determine their angiogenic capacity and future use in regenerative medicine. CKD patients had normal numbers of circulating CD14+ EPC but reduced numbers of circulating CD34+ EPC. Furthermore, EPC from patients with CKD displayed functional impairments, i.e., hampered adherence, reduced endothelial outgrowth potential, and reduced antithrombogenic function. These impairments were already observed at stage 1 CKD and became more apparent when CKD progressed. Dialysis treatment only partially ameliorated EPC impairments in patients with CKD. In conclusion, EPC number and function decrease with advancing CKD, which may hamper physiological vascular repair and can add to the increased risk for cardiovascular diseases observed in CKD patients.

Perioperative iloprost and endothelial progenitor cells in uremic patients with severe limb ischemia undergoing peripheral revascularization

The incidence of severe limb ischemia (SLI) is high among haemodialysis (HD) patients. Limb rescue rate after surgical revascularization is relatively poor compared with patients with normal renal function. Prostanoids are an interesting category as adjuvants to revascularization. New vessel growth develops not exclusively by proliferation of endothelial cells in vascular extremities but also by cells mobilized from the bone marrow (HSC), transformed into endothelial progenitor cells (EPC) contributing to both re-endothelialization and neovascularization. Basal number of HSC and EPC is significantly reduced in HD patients and correlated with a subsequent defective neovascularization. The aim of this study was to evaluate the effects of perioperative treatment with iloprost in uremic patients with acute ischemia of lower limbs, undergoing surgical revascularization, on endothelial progenitor cells, hypothesizing a possible biological mechanism induced by the prostanoids. A search was also made for vascular remodeling processes through the analysis of the concentrations of soluble adhesion molecules (i-CAM, v-CAM, e-selectin), biochemical markers of endothelial activation. Thirty HD patients with SLI undergoing peripheral revascularization were enrolled (15 were treated with iloprost and 15 with a placebo). Iloprost was administered as an intra-arterial bolus of 3000 ng over 1 to 3 min immediately after revascularization and in the same affected artery. Serum samples were taken before revascularization (T0), at 6 (T6) and 24 h (T24) after infusion to measure sICAM-1, sE-selectin, and sVCAM-1, and for quantification of HSC and EPC. Progenitors were identified by specific surface markers CD34+, CD133+ and VEGFR2+. Count was conducted using PROCOUNT performed in a TRUCOUNT tube and with a FACSort flow cytometer. Before revascularization, all patients showed a decreased number of HSC and EPC. After 6 h, HSC augmented significantly compared with T0 in both groups. The iloprost group attained a significant increase compared with the placebo group. HSC levels reduced drastically at T24. EPC augmented significantly compared with basal level after 24 h. In the iloprost group, the increase was considerable compared with the placebo group. A close negative correlation, assessed by Pearson coefficient (r), was found between HSC and EPC at T24 in the iloprost group (R = 0.82 P < 0.01). Adhesion molecules had increased levels at T6 and T24 in both groups. Moreover, a close positive correlation, assessed by Pearson coefficient, was found between EPC and adhesion molecules in both groups but the iloprost group maintained a better statistical association. Revascularization stimulated HSC and EPC release from bone marrow but at a different time: HSC increased suddenly at 6 h and diminished to a minimal amount at T24, conversely, EPC increased significantly only at T24. Iloprost treatment was able to amplify this mechanism validating recent findings (North TE et al., [31]). Adhesion molecules as markers of endothelial activation and vascular development confirmed this tendency.