A reversal of age-dependent proliferative capacity of endothelial progenitor cells from different species origin in in vitro condition

Therapeutic application of regeneration-associated cells: a novel source of regenerative medicine

Chronic diseases with comorbidities or associated risk factors may impair the function of regenerative cells and the regenerative microenvironment. Following this consideration, the vasculogenic conditioning culture (VCC) method was developed to boost the regenerative microenvironment to achieve regeneration-associated cells (RACs), which contain vasculogenic endothelial progenitor cells (EPCs) and anti-inflammatory/anti-immunity cells. Preclinical and clinical studies demonstrate that RAC transplantation is a safe and convenient cell population for promoting ischemic tissue recovery based on its strong vasculogenicity and functionality. The outputs of the scientific reports reviewed in the present study shed light on the fact that RAC transplantation is efficient in curing various diseases. Here, we compactly highlight the universal features of RACs and the latest progress in their translation toward clinics.

Mesenchymal stem cells for critical limb ischemia: their function, mechanism, and therapeutic potential

Peripheral arterial disease is atherosclerotic occlusive disease of the lower extremity arteries and afflicts hundreds of millions of individuals worldwide. Its most severe manifestation is chronic limb-threatening ischemia (Petersen et al. (Science 300(5622):1140–2, 2003)), which is associated with severe pain at rest in the limbs, which progresses to necrosis, limb amputation, and/or death of the patient. Consequently, the care of these patients is considered a financial burden for both patients and health systems. Multidisciplinary endeavors are required to address this refractory disease and to find definitive solutions that lead to improved living conditions. Revascularization is the cornerstone of therapy for preventing limb amputation, and both open vascular surgery and endovascular therapy play a key role in the treatment of patients with CLI. Around one-third of these patients are not candidates for conventional surgical treatment, however, leading to higher amputation rates (approaching 20–25% at one year) with high morbidity and lower quality of life. Advances in regenerative medicine have enabled the development of cell-based therapies that promote the formation of new blood vessels. Particularly, mesenchymal stem cells (MSCs) have emerged as an attractive therapeutic agent in various diseases, including CLI, due to their role in tissue regeneration and immunomodulation. This review discusses the characteristics of MSCs, as well as their regenerative properties and their action mechanisms on CLI.

Autophagy stimulation delayed biological aging and decreased cardiac differentiation in rabbit mesenchymal stem cells

Introduction: Cardiovascular disease (CVD) is a type of disease that affects the function of cardiac-vascular tissues. This study aimed to consider the possible effects of autophagy, as an intrinsic catabolic pathway of cells, on the differentiation and aging process of mesenchymal stem cells (MSCs).

Methods: In this study, bone marrow-derived MSCs were obtained from rabbit bone marrow aspirates. The stemness feature was confirmed by using flow cytometry analysis Cells at passage three were treated with 50 μM Metformin and 15μM hydroxychloroquine (HCQ) for 72 hours. The intracellular accumulation of autophagolysosomes was imaged using LysoTracker staining. Protein levels of autophagy (LC3II/I ratio), aging (Klotho, PARP-1, and Sirt-1) effectors, and cardiomyocyte-like phenotype (α-actinin) were studied by western blotting.

Results: Based on our findings, flow cytometry analysis showed that the obtained cells expressed CD44 and CD133 strongly, and CD31 and CD34 dimly, showing a typical characteristic of MSCs. Our data confirmed an increased LC3II/I ratio in the metformin-received group compared to the untreated and HCQ-treated cells (P < 0.05). Besides, we showed that the incubation of rabbit MSCs with HCQ increased cellular aging by induction of PARP-1 while Metformin increased rejuvenating factor Sirt-1 comparing with the normal group (P < 0.05). Western blotting data showed that the autophagy stimulation response in rabbit MSCs postponed the biological aging and decreased the differentiation potential to the cardiac cells by diminishing α-actinin comparing with control cells (P < 0.05).

Conclusion: In summary, for the informants in this study, it could be noted that autophagy inhibition/stimulation could alter rabbit MSCs aging and differentiation capacity.

Static and dynamic culture of human endothelial cells encapsulated inside alginate-gelatin microspheres

This study aimed to explore the angiogenesis potential of human endothelial cells encapsulated inside alginate-gelatin microspheres under static and dynamic culture systems after 7 days. Human umbilical vein endothelial cells were encapsulated inside alginate (1%) and gelatin (1.2%) using an electrostatic encapsulation method. Cells were incubated for 7 days in vitro. The cell survival rate was measured using the MTT assay. The expression of VEGFR-2 and von Willebrand factor genes was studied by real-time PCR assay. Using western blot analysis, we monitored the protein contents of VEGFR-2, vWF, and Caspase 3. The levels of SOD and GPx enzymes were calculated using biochemical kits. Angiogenesis potential was assessed using in vitro Matrigel assay. Data showed an increased survival rate in encapsulated cells cultured under the static condition compared to the conventional 2D condition (p < 0.05). The culture of encapsulated cells under a dynamic bioreactor system did not alter cell viability. Compared to the dynamic culture system, the incubation of encapsulated cells in the static culture system swelled the microspheres (p < 0.05). Both dynamic and static culture models increased the expression of VEGFR-2 and von Willebrand factor in encapsulated cells compared to 2D culture (p < 0.05), showing enhanced functional maturation. Data showed a significant increase of vWF and reduction of apoptosis marker Caspase in the dynamic culture system (p < 0.05). The levels of SOD and GPx were significantly increased in dynamic and static culture models as compared to the control 2D group (p < 0.05). In vitro tubulogenesis assay showed significant induction of angiogenesis in dynamic encapsulated HUVECs indicated with a large number of vascular tubes and arborized ECs compared to the control and static encapsulated HUVECs (p < 0.05). The current study suggests a bioreactor dynamic system is a reliable approach, similar to a static condition, for the expansion of encapsulated human ECs in a 3D milieu.

Current status of cardiac regenerative medicine; An update on point of view to cell therapy application

Cardiovascular diseases (CVDs) are the leading cause of death globally. Because of the economic and social burden of acute myocardial infarction and its chronic consequences in surviving patients, understanding the pathophysiology of myocardial infarction injury is a major priority for cardiovascular research. MI is defined as cardiomyocytes death caused by an ischemic that resulted from the apoptosis, necrosis, necroptosis, and autophagy. The phases of normal repair following MI including inflammatory, proliferation, and maturation. Normal repair is slow and inefficient generally so that other treatments are required. Because of difficulties, outcomes, and backwashes of traditional therapies including coronary artery bypass grafting, balloon angioplasty, heart transplantation, and artificial heart operations, the novel strategy in the treatment of MI, cell therapy, was newly emerged. In cell therapy, a new population of cells has created that substitute with damaged cells. Different types of stem cell and progenitor cells have been shown to improve cardiac function through various mechanisms, including the formation of new myocytes, endothelial cells, and vascular smooth muscle cells. Bone marrow- and/or adipose tissue-derived mesenchymal stem cells, embryonic stem cells, autologous skeletal myoblasts, induced pluripotent stem cells, endothelial progenitor cells, cardiac progenitor cells and cardiac pericytes considered as a source for cell therapy. In this study, we focused on the point of view of the cell sources.

Exosomes: Biomarkers and Therapeutic Targets of Diabetic Vascular Complications

Diabetic vascular complications (DVC) including macrovascular and microvascular lesions, have a significant impact on public health, and lead to increased patient mortality. Disordered intercellular cascades play a vital role in diabetic systemic vasculopathy. Exosomes participate in the abnormal signal transduction of local vascular cells and mediate the transmission of metabolic disorder signal molecules in distant organs and cells through the blood circulation. They can store different signaling molecules in the membrane structure and release them into the blood, urine, and tears. In recent years, the carrier value and therapeutic effect of exosomes derived from stem cells have garnered attention. Exosomes are not only a promising biomarker but also a potential target and tool for the treatment of DVC. This review explored changes in the production process of exosomes in the diabetic microenvironment and exosomes' early warning role in DVC from different systems and their pathological processes. On the basis of these findings, we discussed the future direction of exosomes in the treatment of DVC, and the current limitations of exosomes in DVC research.

An overview of the myocardial regeneration potential of cardiac c-Kit+ progenitor cells via PI3K and MAPK signaling pathways

In recent years, several studies have investigated cell transplantation as an innovative strategy to restore cardiac function following heart failure. Previous studies have also shown cardiac progenitor cells as suitable candidates for cardiac cell therapy compared with other stem cells. Cellular kit (c-kit) plays an important role in the survival and migration of cardiac progenitor cells. Like other types of cells, in the heart, cellular responses to various stimuli are mediated via coordinated pathways. Activation of c-kit⁺ cells leads to subsequent activation of several downstream mediators such as PI3K and the MAPK pathways. This review aims to outline current research findings on the role of PI3K/AKT and the MAPK pathways in myocardial regeneration potential of c-kit⁺.

Toll-like receptor bioactivity in endothelial progenitor cells

Cardiovascular disease is the main cause of death globally that can be mitigated by the modulation of angiogenesis. To achieve this goal, the application of endothelial progenitor cells and other stem cell types is useful. Following the onset of cardiovascular disease and pro-inflammatory conditions as seen during bacterial sepsis, endothelial progenitor cells enter systemic circulation in response to multiple cytokines and activation of various intracellular mechanisms. The critical role of Toll-like receptors has been previously identified in the dynamics of various cell types, in particular, immune cells. To our knowledge, there are a few experiments related to the role of Toll-like receptors in endothelial progenitor cell activity. Emerging data point of endothelial progenitor cells and other stem cells having the potential to express Toll-like receptors to control different activities such as multipotentiality and dynamics of growth. In this review article, we aim to collect data related to the role of Toll-like receptors in endothelial progenitor cells bioactivity and angiogenic potential.

Crocetin promotes angiogenesis in human endothelial cells through PI3K-Akt-eNOS signaling pathway

Previous studies proved the pro-angiogenic effect of Crocetin, a natural carotenoid dicarboxylic acid, in both in vivo and in vitro models. However, the exact mechanism of Crocetin action has not completely been elucidated yet. The current experiment was designed to find the activity of PI3K-Akt-eNOS axis after the treatment of endothelial cells with Crocetin in vitro. Human Umbilical Vein Endothelial Cells (HUVECs) were incubated with various concentrations of Crocetin (1, 5, 25, 50, and 100 µM) over a period of 72 h. Crocetin significantly increased HUVECs viability after 72 h as compared with the control group. We also found that Crocetin promoted the formation of the capillary-like structure compared to the control (p<0.05). Moreover, an improved migration rate and increased MMP-9 activity were observed in HUVECs that received 50 µM Crocetin (p<0.05). Crocetin enhanced the uptake of Ac-LDL which is correlated with increased lipid metabolism. Based on the data from the current experiment, protein level of VEGFR-1, -2 and p-Akt/Akt, p-eNOS/eNOS ratios were increased 72 h after the treatment of HUVECs with Crocetin (p<0.05). In contrast, the transcription level of VEGF was reduced in Crocetin-treated cells. These data demonstrated that Crocetin promotes HUVECs angiogenesis potential by the modulation of VEGF signaling pathway and increased cell viability. The PI3K/Akt/eNOS axis is required for a Crocetin-associated activity in endothelial cells.

Perivascular adipose tissue-derived stromal cells contribute to vascular remodeling during aging

Aging is an independent risk factor for vascular diseases. Perivascular adipose tissue (PVAT), an active component of the vasculature, contributes to vascular dysfunction during aging. Identification of underlying cell types and their changes during aging may provide meaningful insights regarding the clinical relevance of aging‐related vascular diseases. Here, we take advantage of single‐cell RNA sequence to characterize the resident stromal cells in the PVAT (PVASCs) and identified different clusters between young and aged PVASCs. Bioinformatics analysis revealed decreased endothelial and brown adipogenic differentiation capacities of PVASCs during aging, which contributed to neointimal hyperplasia after perivascular delivery to ligated carotid arteries. Mechanistically, in vitro and in vivo studies both suggested that aging‐induced loss of peroxisome proliferator‐activated receptor‐γ coactivator‐1 α (PGC1α) was a key regulator of decreased brown adipogenic differentiation in senescent PVASCs. We further demonstrated the existence of human PVASCs (hPVASCs) and overexpression of PGC1α improved hPVASC delivery‐induced vascular remodeling. Our finding emphasizes that differentiation capacities of PVASCs alter during aging and loss of PGC1α in aged PVASCs contributes to vascular remodeling via decreased brown adipogenic differentiation.

Tissue engineering strategies for the induction of angiogenesis using biomaterials

Angiogenesis is touted as a fundamental procedure in the regeneration and restoration of different tissues. The induction of de novo blood vessels seems to be vital to yield a successful cell transplantation rate loaded on various scaffolds. Scaffolds are natural or artificial substances that are considered as one of the means for delivering, aligning, maintaining cell connection in a favor of angiogenesis. In addition to the potential role of distinct scaffold type on vascularization, the application of some strategies such as genetic manipulation, and conjugation of pro-angiogenic factors could intensify angiogenesis potential. In the current review, we focused on the status of numerous scaffolds applicable in the field of vascular biology. Also, different strategies and priming approaches useful for the induction of pro-angiogenic signaling pathways were highlighted.

Regulation of plasticity and biological features of endothelial progenitor cells by MSC-derived SDF-1

Bone marrow (BM) is a source of mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs). MSCs provide a specific niche in the BM and biological features of EPCs may be changed with this niche. Stromal cell-derived factor 1 (SDF-1) secreted from primary BM-MSCs and biological features of this niche on EPC development are still yet to be understood. The aim of this study was to evaluate the role of SDF-1 produced by MSCs on EPC development. We applied the CRISPR/Cas9 system for the knock-out of the SDF-1 gene in BM-derived MSCs. BM-derived EPCs were then cocultured with MSCs^SDF-1-/- or MSCs^SDF-1+/+ to identify the role of MSC-derived SDF-1α on proliferation, migration and angiogenic activity of EPCs. Next, pre-expanded EPCs were harvested and co-transplanted with MSCs^SDF-1-/- or MSCs^SDF-1+/+ into sublethally irradiated mice to analyze the potency of these cells for marrow reconstitution. Our results revealed that proliferation, colony formation, migration and angiogenic activity of EPCs was significantly increased after coculture with MSCs^SDF-1+/+. We also found that co-transplantation of EPCs with MSCs^SDF-1+/+, in contrast to MSCs^SDF-1-/-, into irradiated mice resulted in marrow repopulation and hematologic recovery, leading to improved survival of transplanted mice. In conclusions, MSC-derived SDF-1 niche plays an important role in the development of EPCs and this niche is essential for bone marrow repopulation by these cells and can enhance the efficiency of EPC therapy for ischemic diseases.

Distinct role of autophagy on angiogenesis: highlights on the effect of autophagy in endothelial lineage and progenitor cells

Autophagy plays a critical role in the dynamic growth of each cell through different conditions. It seems that this intracellular mechanism acts as a two-edged sword against the numerous cell insults. Previously, autophagy was described in the context of cell activity and behavior, but little knowledge exists related to the role of autophagy in endothelial cells, progenitors, and stem cells biology from different tissues. Angiogenic behavior of endothelial lineage and various stem cells are touted as an inevitable feature in the restoration of different damaged tissues and organs. This capacity was found to be dictated by autophagy signaling pathway. This review article highlights the fundamental role of cell autophagic response in endothelial cells function, stem cells dynamic, and differentiation rate. It seems that elucidation of the mechanisms related to pro- and/or anti-angiogenic potential of autophagy inside endothelial cells and stem cells could help us to modulate stem cell therapeutic feature post-transplantation.

Aging process, adherence to Mediterranean diet and nutritional status in a large cohort of nonagenarians: Effects on endothelial progenitor cells

BACKGROUND AND AIM

Adherence to the Mediterranean Diet (MD) has been associated with a longer and better life. The aim of this study was to examine the effects of adherence to the MD, and of nutritional habits on endothelial progenitor (EPCs) and circulating progenitor (CPCs) cells in a cohort of nonagenarians enrolled within the Mugello Study, an epidemiological study aimed at investigating both clinically relevant geriatric items and various health issues, including those related to nutritional status.

METHODS AND RESULTS

Four hundred twenty-one nonagenarians (306 F, 115 M, mean age: 93.1 ± 3.2 years) were evaluated. Adherence to MD was assessed through the Mediterranean Diet Score. Elderly subjects who were in the fourth quartile of the Mediterranean diet score showed significantly higher EPCs than subjects grouped into the other three quartiles. After adjustment for confounders, elderly subjects who were in the highest quartile of adherence to the MD score reported to have EPCs' levels significantly higher than those who reported lower values of adherence to the MD. Furthermore, by analyzing different food categories, it was reported that daily consumption of olive oil and a higher consumption of fruit and vegetables showed higher CPCs CD34⁺ and EPCs CD34⁺/KDR⁺ than subjects with not daily or lower consumption.

CONCLUSION

Our results support the hypothesis that the adherence to MD, as well as a daily consumption of olive oil and fruit and vegetables, characteristics of MD, may protect against the development of endothelial dysfunction through increasing EPCs and CPCs in older age.

Cardiac progenitor cells application in cardiovascular disease

Stem cells (SCs) have special potency to differentiate into different types of cells, especially cardiomyocytes. In order to demonstrate the therapeutic applications of these cells, various investigations are recently being developed. Cardiac progenitor cells are endogenous cardiac SCs that found to express tyrosine kinase receptors, c-Kit and other stemness features in adult heart, contributing to the regeneration of cardiac tissue after injury. This lineage is able to efficiently trans-differentiate into different cell types such as cardiomyocytes, endothelial cells, and smooth muscle cells. Noticeably, several cardiac progenitor cells have been identified until yet. The therapeutic applications of cardiac SCs have been studied previously, which could introduce a novel therapeutic approach in the treatment of cardiac disorders. The current review enlightens the potency of cardiac progenitor cells features and differentiation capacity, with current applications in cardiovascular field.

Carvacrol promotes angiogenic paracrine potential and endothelial differentiation of human mesenchymal stem cells at low concentrations

OBJECTIVES

Phenolic monoterpene compound, named Carvacrol, has been found to exert different biological outcomes. It has been accepted that the angiogenic activity of human mesenchymal stem cells was crucial in the pursuit of appropriate regeneration. In the current experiment, we investigated the contribution of Carvacrol on the angiogenic behavior of primary human mesenchymal stem cells.

METHODS

Mesenchymal stem cells were exposed to Carvacrol in a dose ranging from 25 to 200μM for 48h. We measured cell survival rate by MTT assay and migration rate by a scratch test. The oxidative status was monitored by measuring SOD, GPx activity. The endothelial differentiation was studied by evaluating the level of VE-cadherin and vWF by real-time PCR and ELISA analyses. The content of VEGF and tubulogenesis behavior was monitored in vitro. We also conducted Matrigel plug in vivo CAM assay to assess the angiogenic potential of conditioned media from human mesenchymal stem cells after exposure to Carvacrol.

RESULTS

Carvacrol was able to increase mesenchymal stem cell survival and migration rate (p<0.05). An increased activity of SOD was obtained while GPx activity unchanged or reduced. We confirmed the endothelial differentiation of stem cells by detecting vWF and VE-cadherin expression (p<0.05). The VEGF expression was increased and mesenchymal stem cells conditioned media improved angiogenesis tube formation in vitro (p<0.05). Moreover, histological analysis revealed an enhanced microvascular density at the site of Matrigel plug in CAM assay.

CONCLUSIONS

Our data shed lights on the possibility of a Carvacrol to induce angiogenesis in human mesenchymal stem cells by modulating cell differentiation and paracrine angiogenic response.

Functional convergence of Akt protein with VEGFR-1 in human endothelial progenitor cells exposed to sera from patient with type 2 diabetes mellitus

Diabetes mellitus type 2 predisposes patients to various microvascular complications. In the current experiment, the potent role of diabetes mellitus was investigated on the content of VEGFR-1, -2, Tie-1 and -2, and Akt in human endothelial progenitor cells. The gene expression profile of mTOR and Hedgehog signaling pathways were measured by PCR array. The possible crosstalk between RTKs, mTOR and Hedgehog signaling was also studied by bioinformatic analysis. Endothelial progenitor cells were incubated with serum from normal and diabetic for 7days. Compared to non-treated cells, diabetic serum-induced cell apoptosis (~2-fold) and prohibited cell migration toward bFGF (p<0.001). ELISA analysis showed that diabetes exposed cells had increased abundance of Tie-1, -2 and VEGFR-2 and reduced amount of VEGFR-1 (p<0.0001) in diabetic cells. Western blotting showed a marked reduction in the protein level of Akt after cells exposure to serum from diabetic subjects (p<0.0001). PCR array revealed a significant stimulation of both mTOR and Hedgehog signaling pathways in diabetic cells (p<0.05). According to data from bioinformatic datasets, we showed VEGFR-1, -2 and Tie-2, but not Tie-1, are master regulators of angiogenesis. There is a crosstalk between RTKs and mTOR signaling by involving P62, GABARAPL1, and HTT genes. It seems that physical interaction and co-expression of Akt decreased the level of VEGFR-1 in diabetic cells. Regarding data from the present experiment, diabetic serum contributed to uncontrolled induction of both mTOR and Hedgehog signaling in endothelial progenitor cells. Diabetes mellitus induces mTOR pathway by involving receptor tyrosine kinases while Hedgehog stimulation is independent of these receptors.

Angiogenic and Restorative Abilities of Human Mesenchymal Stem Cells Were Reduced Following Treatment With Serum From Diabetes Mellitus Type 2 Patients

This experiment investigated the impact of serum from patients with type 2 diabetes mellitus on the angiogenic behavior of human mesenchymal stem cells in vitro. Changes in the level of Ang-1, Ang-2, cell migration, and trans-differentiation into pericytes and endothelial lineage were monitored after 7 days. The interaction of mesenchymal stem cells with endothelial cells were evaluated using surface plasmon resonance technique. Paracrine restorative effect of diabetic stem cells was tested on pancreatic β cells. Compared to data from FBS and normal serum, diabetic serum reduced the stem cell survival and chemotaxis toward VEGF and SDF-1α (P < 0.05). Diabetic condition were found to decline cell migration rate and the activity of MMP-2 and -9 (P < 0.05). The down-regulation of VEGFR-2 and CXCR-4 was observed with an increase in the level of miR-1-3p and miR-15b-5p at the same time. The paracrine angiogenic potential of diabetic stem cells was disturbed via the changes in the dynamic of Ang-1, Ang-2, and VEGF. Surface plasmon resonance analysis showed that diabetes could induce an aberrant increase in the interaction of stem cells with endothelial cells. After treatment with diabetic serum, the expression of VE-cadherin and NG2 and ability for uptake of Dil-Ac-LDL were reduced (P < 0.01). Conditioned media prepared from diabetic stem cells were unable to decrease fatty acid accumulation in β-cells (P < 0.05). The level of insulin secreted by β-cells was not affected after exposure to supernatant from diabetic or non-diabetic mesenchymal stem cells. Data suggest diabetes could decrease angiogenic and restorative effect of stem cells in vitro. J. Cell. Biochem. 119: 524-535, 2018. © 2017 Wiley Periodicals, Inc.