Valsartan impairs angiogenesis of mesenchymal stem cells through Akt pathway

Systematic review and meta-analysis of the effect of bone marrow-derived cell therapies on hind limb perfusion

Preclinical and clinical studies on the administration of bone marrow-derived cells to restore perfusion show conflicting results. We conducted a systematic review and meta-analysis on preclinical studies to assess the efficacy of bone marrow-derived cells in the hind limb ischemia model and identify possible determinants of therapeutic efficacy. In vivo animal studies were identified using a systematic search in PubMed and EMBASE on 10 January 2022. 85 studies were included for systematic review and meta-analysis. Study characteristics and outcome data on relative perfusion were extracted. The pooled mean difference was estimated using a random effects model. Risk of bias was assessed for all included studies. We found a significant increase in perfusion in the affected limb after administration of bone marrow-derived cells compared to that in the control groups. However, there was a high heterogeneity between studies, which could not be explained. There was a high degree of incomplete reporting across studies. We therefore conclude that the current quality of preclinical research is insufficient (low certainty level as per GRADE assessment) to identify specific factors that might improve human clinical trials.

MiR-27a targets DKK2 and SFRP1 to promote reosseointegration in the regenerative treatment of peri-implantitis

In the inflamed microenvironment of peri-implantitis, limited osteogenesis on the implant surface impedes well-established reosseointegration using current clinical therapies. MicroRNAs (miRNAs) function as potent molecular managers that may simultaneously regulate multiple endogenous processes such as inflammation and osteogenesis. The delivery of miRNAs may provide a way to effectively treat some diseases. In this study, we showed that miR-27a was differentially downregulated in samples from a canine peri-implantitis model. We found that overexpressing miR-27a positively regulated osteogenesis-angiogenesis coupling by ameliorating the TNF-α inhibition of bone formation in vitro. Mechanistically, we identified Dickkopf2 (DKK2) and secreted frizzled related protein 1 (SFRP1) as two essential direct miR-27a targets that were osteogenic and angiogenic. Furthermore, we constructed a miR-27a-enhanced delivery system to repair the bone defect around implants in a canine peri-implantitis model. The results demonstrated that the miR-27a-treated group could optimize new bone formation and reosseointegration in vivo. Our assay provides evidence that this strategy exerts therapeutic effects on peri-implantitis, suggesting that it represents a feasible method to maintain the stability and masticatory function of dental implants. © 2018 American Society for Bone and Mineral Research.

Stem Cell-Mediated Angiogenesis in Tissue Engineering Constructs

Angiogenesis has always been a concern in the field of tissue engineering. Poor vascularization of engineered constructs is a problem for the clinical success of these structures. Among the various methods employed to induce angiogenesis, stem cells provide a promising tool for the future. The present review aims to present the application of stem cells in the induction of angiogenesis. Additionally, it summarizes recent advancements in stem cell-mediated angiogenesis of different tissue engineering constructs.

Gene and microRNA transcriptional signatures of angiotensin II in endothelial cells

Growth of atherosclerotic plaque requires neovascularization (angiogenesis). To elucidate the involvement of angiotensin II (Ang II) in angiogenesis, we performed gene microarray and microRNA (miRNA) polymerase chain reaction array analyses on human coronary artery endothelial cells exposed to moderate concentration of Ang II for 2 and 12 hours. At 12, but not 2, hours, cultures treated with Ang II exhibited shifts in transcriptional activity involving 267 genes (>1.5-fold difference; P < 0.05). Resulting transcriptome was most significantly enriched for genes associated with blood vessel development, angiogenesis, and regulation of proliferation. Majority of upregulated genes implicated in angiogenesis shared a commonality of being either regulators (HES1, IL-18, and CXCR4) or targets (ADM, ANPEP, HES1, KIT, NOTCH4, PGF, and SOX18) of STAT3. In line with these findings, STAT3 inhibition attenuated Ang II-dependent stimulation of tube formation in Matrigel assay. Expression analysis of miRNAs transcripts revealed that the pattern of differential expression for miRNAs was largely consistent with proangiogenic response with a prominent theme of upregulation of miRs targeting PTEN (miR-19b-3p, miR-21-5p, 23b-3p, and 24-3p), many of which are directly or indirectly STAT3 dependent. We conclude that STAT3 signaling may be an intrinsic part of Ang II-mediated proangiogenic response in human endothelial cells.

Role of angiotensin II in stem cell therapy of cardiac disease

INTRODUCTION

The renin angiotensin system (RAS) is closely related to the cardiovascular system, body fluid regulation and homeostasis.

MATERIALS AND METHODS

Despite common therapeutic methods, stem cell/progenitor cell therapy is daily increasing as a term of regenerative medicine. RAS and its pharmacological inhibitors are not only involved in physiological and pathological aspects of the cardiovascular system, but also affect the different stages of stem cell proliferation, differentiation and function, via interfering cell signaling pathways.

RESULTS

This study reviews the new role of RAS, in particular Ang II distinct from other common roles, by considering its regulating impact on the different signaling pathways involved in the cardiac and endothelial tissue, as well as in stem cell transplantation.

CONCLUSIONS

This review focuses on the impact of stem cell therapy on the cardiovascular system, the role of RAS in stem cell differentiation, and the role of RAS inhibition in cardiac stem cell growth and development.

Angiotensin receptor blockers: Focus on cardiac and renal injury

Angiotensin II, an important component of renin angiotensin system, is a potent vasopressor and its actions are mostly mediated via angiotensin II type 1 receptor (AT1R) and role of AT2R in counterbalancing the actions of AT1R stimulation are under extensive research. In addition to its physiological actions, angiotensin II plays important roles in the pathogenesis of atherosclerosis, hypertension, left ventricular hypertrophy, and heart failure. The effects of angiotensin II can be blocked by either suppressing its production by blocking angiotensin converting enzyme or by antagonizing its actions on AT1R using angiotensin II receptor blockers (ARBs). Instead of the extensive use of ARBs in the treatment of various cardiovascular diseases, proper selection of a particular ARB is crucial as the clinical condition of individual patient is different and also their economic status would play an essential role in medication compliance. Thus a critical review of the proven and promising actions of ARBs against various pathological conditions will be of great importance for the clinicians as well as for the researchers.

Pretreatment of mesenchymal stem cells with angiotensin II enhances paracrine effects, angiogenesis, gap junction formation and therapeutic efficacy for myocardial infarction

BACKGROUND

Pretreatment of mesenchymal stem cells (MSCs) with growth factors is reported to be an effective route for improving cell-based therapy of myocardial infarction (MI). Angiotensin II (Ang II) triggers vascular endothelial growth factor (VEGF) synthesis in MSCs. This study aimed to investigate the effects and mechanisms of Ang II pretreatment in enhancing the therapeutic efficacy of MSCs in MI.

METHODS

MSCs and endothelial cells (ECs) were isolated from Sprague-Dawley rats. After pretreated with or without 100 nM of Ang II for 24 h, the MSCs were directly injected into the border zones of the ischemic heart. Cardiac function, fibrosis, infarct size, VEGF expression, angiogenesis, and cell differentiation in the infarcted myocardium were determined after 30 days. The cell apoptosis of MSCs post hypoxia was assessed using flow cytometry. The angiogenic activity of MSCs was analyzed using tube formation assay. The gap junction protein connexin-43 (Cx43) expression was detected.

RESULTS

Compared with the MSC group, pretreatment of MSCs with Ang II resulted in better cardiac function, less cardiac fibrosis, smaller infarct size, and higher expression of VEGF and Von Willebrand Factor in ischemic myocardium, but no promotion of cardiomyocyte-like differentiation of MSCs. Ang II pretreatment enhanced the survival of MSCs and the H9c2 cells surrounding MSCs, and augmented the tube formation of ECs and MSCs. Ang II pretreatment up-regulated the Cx43 expression.

CONCLUSIONS

The pretreatment of MSCs with Ang II improved the outcome of MSC-based therapy for MI via the mechanisms of enhancing the paracrine production of VEGF, angiogenesis, and gap junction formation.

Bone marrow mononuclear cell angiogenic competency is suppressed by a high-salt diet

Autologous bone marrow-derived mononuclear cell (BM-MNC) transplantation is a potential therapy for inducing revascularization in ischemic tissues providing the underlying disease process had not negatively affected BM-MNC function. Previously, we have shown that skeletal muscle angiogenesis induced by electrical stimulation is impaired by a high-salt diet (HSD; 4% NaCl) in Sprague-Dawley (SD) rats. In this study we tested the hypothesis that BM-MNC angiogenic function is impaired by an elevated dietary sodium intake. Following 1 wk on HSD, either vehicle or BM-MNCs derived from SD donor rats on HSD or normal salt diet (NSD; 0.4% NaCl) were injected into male SD rats undergoing hindlimb stimulation. Administration of BM-MNCs (intramuscular or intravenous) from NSD donors, but not HSD donors, restored the angiogenic response in HSD recipients. Angiotensin II (3 ng · kg(-1) · min(-1)) infusion of HSD donor rats restored angiogenic capacity of BM-MNCs, and treatment of NSD donor rats with losartan, an angiotensin II receptor-1 antagonist, inhibited BM-MNC angiogenic competency. HSD BM-MNCs and NSD losartan BM-MNCs exhibited increased apoptosis in vitro following an acute 6-h hypoxic stimulus. HSD BM-MNCs also had increased apoptosis following injection into skeletal muscle. This study suggests that BM-MNC transplantation can restore skeletal muscle angiogenesis and that HSD impairs the angiogenic competency of BM-MNCs due to suppression of the renin-angiotensin system causing increased apoptosis.