Outgrowth endothelial cells: sources, characteristics and potential applications in tissue engineering and regenerative medicine

The Effects of Platelet-Rich Fibrin in the Behavior of Mineralizing Cells Related to Bone Tissue Regeneration-A Scoping Review of In Vitro Evidence

Platelet-rich fibrin (PRF) is a second-generation blood concentrate that serves as an autologous approach for both soft and hard tissue regeneration. It provides a scaffold for cell interaction and promotes the local release of growth factors. PRF has been investigated as an alternative to bone tissue therapy, with the potential to expedite wound healing and bone regeneration, though the mechanisms involved are not yet fully understood. This review aims to explore the in vitro evidence of PRF's effects on the behavior of mineralizing cells related to bone tissue regeneration. A systematic electronic search was conducted up to August 2023, utilizing three databases: PubMed, Web of Science, and Scopus. A total of 76 studies were selected, which presented in vitro evidence of PRF's usefulness, either alone or in conjunction with other biomaterials, for bone tissue treatment. PRF membranes' influence on the proliferation, differentiation, and mineralization of bone cells is linked to the constant release of growth factors, resulting in changes in crucial markers of bone cell metabolism and behavior. This further reinforces their therapeutic potential in wound healing and bone regeneration. While there are some notable differences among the studies, the overall results suggest a positive effect of PRF on cell proliferation, differentiation, mineralization, and a reduction in inflammation. This points to its therapeutic potential in the field of regenerative medicine. Collectively, these findings may help enhance our understanding of how PRF impacts basic physiological processes in bone and mineralized tissue.

Efficacy of Low-Intensity Extracorporeal Shock Wave Treatment in Erectile Dysfunction following Radical Prostatectomy: A Systematic Review and Meta-Analysis

Erectile dysfunction (ED) is a well-known complication of radical prostatectomy (RP). Oral 5-phosphodiesterase inhibitors are currently the most widely used penile rehabilitation treatment for ED following RP, but they are less effective than for those with general ED. Low-intensity extracorporeal shock wave treatment (LI-ESWT), causing a biological change that induces neovascularization, has recently been used as a treatment for ED. Therefore, we conducted a systematic review and meta-analysis to investigate the efficiency of LI-ESWT in ED following RP. PubMed, Embase, and the Cochrane Library were searched up until December 2021. The endpoint was the change in IIEF scores after LI-ESWT. Five papers (460 patients) were included in the final analysis. In IIEF scores performed 3–4 months after LI-ESWT, the group receiving LI-ESWT showed statistically significantly better results than the control (WMD = −2.04; 95% CI, −3.72 to −0.35; p = 0.02). However, there were a total of two studies that measured the results after 9–12 months. There was no statistical difference between the two groups (WMD = −5.37; 95% CI, −12.42 to 1.69; p = 0.14). The results of this analysis indicate that LI-ESWT showed a statistically significant effect on early recovery in penile rehabilitation of ED following RP. However, the level of evidence was low. Therefore, careful interpretation of the results is required.

Comparative Evaluation on Impacts of Fibronectin, Heparin-Chitosan, and Albumin Coating of Bacterial Nanocellulose Small-Diameter Vascular Grafts on Endothelialization In Vitro

In this study, we contrast the impacts of surface coating bacterial nanocellulose small-diameter vascular grafts (BNC-SDVGs) with human albumin, fibronectin, or heparin–chitosan upon endothelialization with human saphenous vein endothelial cells (VEC) or endothelial progenitor cells (EPC) in vitro. In one scenario, coated grafts were cut into 2D circular patches for static colonization of a defined inner surface area; in another scenario, they were mounted on a customized bioreactor and subsequently perfused for cell seeding. We evaluated the colonization by emerging metabolic activity and the preservation of endothelial functionality by water soluble tetrazolium salts (WST-1), acetylated low-density lipoprotein (AcLDL) uptake assays, and immune fluorescence staining. Uncoated BNC scaffolds served as controls. The fibronectin coating significantly promoted adhesion and growth of VECs and EPCs, while albumin only promoted adhesion of VECs, but here, the cells were functionally impaired as indicated by missing AcLDL uptake. The heparin–chitosan coating led to significantly improved adhesion of EPCs, but not VECs. In summary, both fibronectin and heparin–chitosan coatings could beneficially impact the endothelialization of BNC-SDVGs and might therefore represent promising approaches to help improve the longevity and reduce the thrombogenicity of BNC-SDVGs in the future.

Chitlac-coated Thermosets Enhance Osteogenesis and Angiogenesis in a Co-culture of Dental Pulp Stem Cells and Endothelial Cells

Dental pulp stem cells (DPSCs) represent a population of stem cells which could be useful in oral and maxillofacial reconstruction. They are part of the periendothelial niche, where their crosstalk with endothelial cells is crucial in the cellular response to biomaterials used for dental restorations. DPSCs and the endothelial cell line EA.hy926 were co-cultured in the presence of Chitlac-coated thermosets in culture conditions inducing, in turn, osteogenic or angiogenic differentiation. Cell proliferation was evaluated by 3-[4,5-dimethyl-thiazol-2-yl-]-2,5-diphenyl tetrazolium bromide (MTT) assay. DPSC differentiation was assessed by measuring Alkaline Phosphtase (ALP) activity and Alizarin Red S staining, while the formation of new vessels was monitored by optical microscopy. The IL-6 and PGE2 production was evaluated as well. When cultured together, the proliferation is increased, as is the DPSC osteogenic differentiation and EA.hy926 vessel formation. The presence of thermosets appears either not to disturb the system balance or even to improve the osteogenic and angiogenic differentiation. Chitlac-coated thermosets confirm their biocompatibility in the present co-culture model, being capable of improving the differentiation of both cell types. Furthermore, the assessed co-culture appears to be a useful tool to investigate cell response toward newly synthesized or commercially available biomaterials, as well as to evaluate their engraftment potential in restorative dentistry.

3D bioprinting of heterogeneous bi- and tri-layered hollow channels within gel scaffolds using scalable multi-axial microfluidic extrusion nozzle

One of the primary focuses in recent years in tissue engineering has been the fabrication and integration of vascular structures into artificial tissue constructs. However, most available methodologies lack the ability to create multi-layered concentric conduits inside natural extracellular matrices (ECMs) and gels that replicate more accurately the hierarchical architecture of biological blood vessels. In this work, we present a new microfluidic nozzle design capable of multi-axial extrusion in order to 3D print and pattern bi- and tri-layered hollow channel structures. This nozzle allows, for the first time, for these structures to be embedded within layers of gels and ECMs in a fast, simple and low-cost manner. By varying flow rates (1-6 ml min^-1), printspeeds (1-16 m min^-1), and material concentration (25-175 mM and 1.5%-2.5% for calcium chloride and alginate, respectively) we are able to accurately determine the operational printing range as well as achieve a wide range of conduit dimensions (0.69-2.31 mm) that can be printed within a few seconds. Our scalable design allows for multi-axial extrusion and versatility in material incorporation in order to create heterogeneous structures. We demonstrate the ability to print distinct concentric layers of different cell types, namely endothelial cells and fibroblasts. By incorporating various layers of different cell-friendly materials (such as collagen and fibrin) alongside materials with high mechanical strength (i.e. alginate), we were able to increase long-term cell viability and growth without compromising the structural integrity. In this way, we can improve cellular adhesion in our biocompatible constructs as well as allow them to remain structurally sound. We are able to realize complex heterogeneous, hierarchical architectures that have strong potential for use not only in vascular tissue applications, but also in other artificially fabricated tubular or fiber-like structures such as skeletal muscle or nerve conduits.

Site-specific and endothelial-mediated dysfunction of the alveolar-capillary barrier in response to lipopolysaccharides

Infectious agents such as lipopolysaccharides (LPS) challenge the functional properties of the alveolar‐capillary barrier (ACB) in the lung. In this study, we analyse the site‐specific effects of LPS on the ACB and reveal the effects on the individual cell types and the ACB as a functional unit. Monocultures of H441 epithelial cells and co‐cultures of H441 with endothelial cells cultured on Transwells^® were treated with LPS from the apical or basolateral compartment. Barrier properties were analysed by the transepithelial electrical resistance (TEER), by transport assays, and immunostaining and assessment of tight junctional molecules at protein level. Furthermore, pro‐inflammatory cytokines and immune‐modulatory molecules were evaluated by ELISA and semiquantitative real‐time PCR. Liquid chromatography–mass spectrometry‐based proteomics (LS‐MS) was used to identify proteins and effector molecules secreted by endothelial cells in response to LPS. In co‐cultures treated with LPS from the basolateral compartment, we noticed a significant reduction of TEER, increased permeability and induction of pro‐inflammatory cytokines. Conversely, apical treatment did not affect the barrier. No changes were noticed in H441 monoculture upon LPS treatment. However, LPS resulted in an increased expression of pro‐inflammatory cytokines such as IL‐6 in OEC and in turn induced the reduction of TEER and an increase in SP‐A expression in H441 monoculture, and H441/OEC co‐cultures after LPS treatment from basolateral compartment. LS‐MS‐based proteomics revealed factors associated with LPS‐mediated lung injury such as ICAM‐1, VCAM‐1, Angiopoietin 2, complement factors and cathepsin S, emphasizing the role of epithelial–endothelial crosstalk in the ACB in ALI/ARDS.

Novel therapeutic roles for surfactant-inositols and -phosphatidylglycerols in a neonatal piglet ARDS model: a translational study

The biological and immune-protective properties of surfactant-derived phospholipids and phospholipid subfractions in the context of neonatal inflammatory lung disease are widely unknown. Using a porcine neonatal triple-hit acute respiratory distress syndrome (ARDS) model (repeated airway lavage, overventilation, and LPS instillation into airways), we assessed whether the supplementation of surfactant (S; poractant alfa) with inositol derivatives [inositol 1,2,6-trisphosphate (IP3) or phosphatidylinositol 3,5-bisphosphate (PIP2)] or phosphatidylglycerol subfractions [16:0/18:1-palmitoyloleoyl-phosphatidylglycerol (POPG) or 18:1/18:1-dioleoyl-phosphatidylglycerol (DOPG)] would result in improved clinical parameters and sought to characterize changes in key inflammatory pathways behind these improvements. Within 72 h of mechanical ventilation, the oxygenation index (S+IP3, S+PIP2, and S+POPG), the ventilation efficiency index (S+IP3 and S+POPG), the compliance (S+IP3 and S+POPG) and resistance (S+POPG) of the respiratory system, and the extravascular lung water index (S+IP3 and S+POPG) significantly improved compared with S treatment alone. The inositol derivatives (mainly S+IP3) exerted their actions by suppressing acid sphingomyelinase activity and dependent ceramide production, linked with the suppression of the inflammasome nucleotide-binding domain, leucine-rich repeat-containing protein-3 (NLRP3)-apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-caspase-1 complex, and the profibrotic response represented by the cytokines transforming growth factor-β1 and IFN-γ, matrix metalloproteinase (MMP)-1/8, and elastin. In addition, IκB kinase activity was significantly reduced. S+POPG and S+DOPG treatment inhibited polymorphonuclear leukocyte activity (MMP-8 and myeloperoxidase) and the production of interleukin-6, maintained alveolar-capillary barrier functions, and reduced alveolar epithelial cell apoptosis, all of which resulted in reduced pulmonary edema. S+DOPG also limited the profibrotic response. We conclude that highly concentrated inositol derivatives and phosphatidylglycerol subfractions in surfactant preparations mitigate key inflammatory pathways in inflammatory lung disease and that their clinical application may be of interest for future treatment of the acute exudative phase of neonatal ARDS.

Platelet-rich fibrin-based matrices to improve angiogenesis in an in vitro co-culture model for bone tissue engineering

In the context of prevascularization strategies for tissue‐engineering purposes, co‐culture systems consisting of outgrowth endothelial cells (OECs) and primary osteoblasts (pOBs) have been established as a promising in vitro tool to study regeneration mechanisms and to identify factors that might positively influence repair processes such as wound healing or angiogenesis. The development of autologous injectable platelet‐rich fibrin (PRF), which can be generated from peripheral blood in a minimal invasive procedure, fulfils several requirements for clinically applicable cell‐based tissue‐engineering strategies. During this study, the established co‐culture system of OECs and pOBs was mixed with injectable PRF and was cultivated in vitro for 24 h or 7 days. The aim of this study was to analyse whether PRF might have a positive effect on wound healing processes and angiogenic activation of OECs in the co‐culture with regard to proinflammatory factors, adhesion molecules and proangiogenic growth factor expression. Histological cell detection revealed the formation of lumina and microvessel‐like structures in the PRF/co‐culture complexes after 7 days of complex cultivation. Interestingly, the angiogenic activation of OECs was accompanied by an upregulation of wound healing‐associated factors, as well as by a higher expression of the proangiogenic factor vascular endothelial growth factor, which was evaluated both on the mRNA level as well as on the protein level. Thus, PRF might positively influence wound healing processes, in particular angiogenesis, in the in vitro co‐culture, making autologous PRF‐based matrices a beneficial therapeutic tool for tissue‐engineering purposes by simply profiting from the PRF, which contains blood plasma, platelets and leukocytes.

Co-culture of outgrowth endothelial cells with human mesenchymal stem cells in silk fibroin hydrogels promotes angiogenesis

Sufficient vascularization of the implant construct is required for tissue regeneration to ensure the supply of oxygen and nutrients. In our previous work, we established sonication-induced silk fibroin hydrogel to load neural stem cells for brain tissue engineering applications. In this study, we explored the application of silk fibroin as an injectable hydrogel for vascularization of soft tissues. We investigated the ability of outgrowth endothelial cells (OECs) in mono-culture or in co-culture with human bone marrow-derived mesenchymal stem cells (BM-MSCs) to form capillary networks in silk fibroin hydrogels. Furthermore, the silk fibroin hydrogel was modified with IKVAV peptide revealing a sequence derived from the extracellular matrix component laminin-1 to test its effects on angiogenesis, using unmodified and VVIAK modified silk fibroin hydrogel as controls. In monocultures of OECs, no angiogenic structures were observed in silk fibroin hydrogels. In contrast, vascular structures were abundant and increased in co-culture, as confirmed by immunocytochemistry and scanning electron microscopy (SEM) over 10 d of culture in silk fibroin-based hydrogels. Although no significant differences in angiogenic activity seem to be caused by the IKVAV peptide in our experimental settings, these results indicate that sonication-induced silk fibroin-based hydrogels support the formation of functional endothelial tubes and vascularization networks in the presence of mesenchymal cells supporting the vascular sprouting of endothelial cells.

Stimulatory Influences of Far Infrared Therapy on the Transcriptome and Genetic Networks of Endothelial Progenitor Cells Receiving High Glucose Treatment

BACKGROUND

Endothelial progenitor cells (EPCs) play a fundamental role in vascular repair and angiogenesis- related diseases. It is well-known that the process of angiogenesis is faulty in patients with diabetes. Long-term exposure of peripheral blood EPCs to high glucose (HG-EPCs) has been shown to impair cell proliferation and other functional competencies. Far infrared (FIR) therapy can promote ischemia-induced angiogenesis in diabetic mice and restore high glucose-suppressed endothelial progenitor cell functions both in vitro and in vivo. However, the detail mechanisms and global transcriptome alternations are still unclear.

METHODS

In this study, we investigated the influences of FIR upon HG-EPC gene expressions. EPCs were obtained from the peripheral blood and treated with high glucose. These cells were then subjected to FIR irradiation and functional assays.

RESULTS

Those genes responsible for fibroblast growth factors, Mitogen-activated protein kinases (MAPK), Janus kinase/signal transducer and activator of transcription and prostaglandin signaling pathways were significantly induced in HG-EPCs after FIR treatment. On the other hand, mouse double minute 2 homolog, genes involved in glycogen metabolic process, and genes involved in cardiac fibrosis were down-regulated. We also observed complex genetic networks functioning in FIR-treated HG-EPCs, in which several genes, such as GATA binding protein 3, hairy and enhancer of split-1, Sprouty Homolog 2, MAPK and Sirtuin 1, acted as hubs to maintain the stability and connectivity of the whole genetic network.

CONCLUSIONS

Deciphering FIR-affected genes will not only provide us with new knowledge regarding angiogenesis, but also help to develop new biomarkers for evaluating the effects of FIR therapy. Our findings may also be adapted to develop new methods to increase EPC activities for treating diabetes-related ischemia and metabolic syndrome-associated cardiovascular disorders.

KEY WORDS

Endothelial progenitor cell; Far infrared; Microarray; Systems biology.

Recent advances in bone regeneration using adult stem cells

Bone is a highly vascularized tissue reliant on the close spatial and temporal association between blood vessels and bone cells. Therefore, cells that participate in vasculogenesis and osteogenesis play a pivotal role in bone formation during prenatal and postnatal periods. Nevertheless, spontaneous healing of bone fracture is occasionally impaired due to insufficient blood and cellular supply to the site of injury. In these cases, bone regeneration process is interrupted, which might result in delayed union or even nonunion of the fracture. Nonunion fracture is difficult to treat and have a high financial impact. In the last decade, numerous technological advancements in bone tissue engineering and cell-therapy opened new horizon in the field of bone regeneration. This review starts with presentation of the biological processes involved in bone development, bone remodeling, fracture healing process and the microenvironment at bone healing sites. Then, we discuss the rationale for using adult stem cells and listed the characteristics of the available cells for bone regeneration. The mechanism of action and epigenetic regulations for osteogenic differentiation are also described. Finally, we review the literature for translational and clinical trials that investigated the use of adult stem cells (mesenchymal stem cells, endothelial progenitor cells and CD34⁺ blood progenitors) for bone regeneration.

Fibroblast-endothelial partners for vascularization strategies in tissue engineering

Cell-based approaches have emerged as a promising therapy to achieve successful vascularization in tissue engineering. Since fibroblasts activation and migration is required for physiological events relying on angiogenesis, we hypothesize herein that different fibroblasts exhibit distinct capacity to promote capillary-like structures assembly, by mature and progenitor endothelial cells (ECs). Outgrowth endothelial cells (OECs) were isolated from human umbilical cord blood samples and characterized by immunofluorescence and imaging flow cytometry for endothelial markers. Coculture systems were established using either human umbilical vein ECs (HUVECs) or OECs with fibroblasts, being evaluated at 7, 14, and 21 days of culture. Two types of human dermal fibroblasts (HDF) were used, namely neonatal human foreskin fibroblasts-1 (HFF-1) and juvenile HDF. OECs expressed EC markers and formed capillary-like structures. HFF-1 exhibited higher expression of transglutaminase-2, while HDF exhibited a higher expression of α-smooth muscle actin (α-SMA) and podoplanin, which were not observed for HFF-1. Formation of capillary-like structures was only observed in cocultures with HDF and not with HFF-1. No significant differences were found between HDF and OECs or HUVECs cocultures. These findings suggest that HDF is a preferential cell source for promoting vascularization, either using mature or progenitor ECs, probably due to their higher expression of α-SMA and podoplanin, and increased synthesis of extracellular matrix. This work opens new research possibilities regarding the use of specific fibroblast populations cocultured with ECs, as efficient partners for vascular development in regenerative medicine strategies.

Connections matter: channeled hydrogels to improve vascularization

The use of cell-laden hydrogels to engineer soft tissue has been emerging within the past years. Despite, several newly developed and sophisticated techniques to encapsulate different cell types the importance of vascularization of the engineered constructs is often underestimated. As a result, cell death within a construct leads to impaired function and inclusion of the implant. Here, we discuss the fabrication of hollow channels within hydrogels as a promising strategy to facilitate vascularization. Furthermore, we present an overview on the feasible use of removable spacers, 3D laser-, and planar processing strategies to create channels within hydrogels. The implementation of these structures promotes control over cell distribution and increases oxygen transport and nutrient supply in vitro. However, many studies lack the use of endothelial cells in their approaches leaving out an important factor to enhance vessel ingrowth and anastomosis formation upon implantation. In addition, the adequate endothelial cell type needs to be considered to make these approaches bridge the gap to in vivo applications.

miRNome traits analysis on endothelial lineage cells discloses biomarker potential circulating microRNAs which affect progenitor activities

Background

Endothelial progenitor cells (EPCs) play a fundamental role in not only blood vessel development but also post-natal vascular repair. Currently EPCs are defined as early and late EPCs based on their biological properties and their time of appearance during in vitro culture. Both EPC types assist angiogenesis and have been linked to ischemia-related disorders, including coronary artery disease (CAD).

Results

We found late EPCs are more mobile than early EPCs and matured endothelial cells (ECs). To pinpoint the mechanism, microRNA profiles of early EPCs late EPCs, and ECs were deciphered by small RNA sequencing. Obtained signatures made up of both novel and known microRNAs, in which anti-angiogenic microRNAs such as miR-221 and miR-222 are more abundant in matured ECs than in late EPCs. Overexpression of miR-221 and miR-222 resulted in the reduction of genes involved in hypoxia response, metabolism, TGF-beta signalling, and cell motion. Not only hamper late EPC activities in vitro, both microRNAs (especially miR-222) also hindered in vivo vasculogenesis in a zebrafish model. Reporter assays showed that miR-222, but not miR-221, targets the angiogenic factor ETS1. In contrast, PIK3R1 is the target of miR-221, but not miR-222 in late EPCs. Clinically, both miR-221-PIK3R1 and miR-222-ETS1 pairs are deregulated in late EPCs of CAD patients.

Conclusions

Our results illustrate EPCs and ECs exploit unique miRNA modalities to regulate angiogenic features, and explain why late EPC levels and activities are reduced in CAD patients. These data will further help to develop new plasma biomarkers and therapeutic approaches for ischemia-related diseases or tumor angiogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-802) contains supplementary material, which is available to authorized users.

Cell communication in a coculture system consisting of outgrowth endothelial cells and primary osteoblasts

Bone tissue is a highly vascularized and dynamic system with a complex construction. In order to develop a construct for implant purposes in bone tissue engineering, a proper understanding of the complex dependencies between different cells and cell types would provide further insight into the highly regulated processes during bone repair, namely, angiogenesis and osteogenesis, and might result in sufficiently equipped constructs to be beneficial to patients and thereby accomplish their task. This study is based on an in vitro coculture model consisting of outgrowth endothelial cells and primary osteoblasts and is currently being used in different studies of bone repair processes with special regard to angiogenesis and osteogenesis. Coculture systems of OECs and pOBs positively influence the angiogenic potential of endothelial cells by inducing the formation of angiogenic structures in long-term cultures. Although many studies have focused on cell communication, there are still numerous aspects which remain poorly understood. Therefore, the aim of this study is to investigate certain growth factors and cell communication molecules that are important during bone repair processes. Selected growth factors like VEGF, angiopoietins, BMPs, and IGFs were investigated during angiogenesis and osteogenesis and their expression in the cultures was observed and compared after one and four weeks of cultivation. In addition, to gain a better understanding on the origin of different growth factors, both direct and indirect coculture strategies were employed. Another important focus of this study was to investigate the role of “gap junctions,” small protein pores which connect adjacent cells. With these bridges cells are able to exchange signal molecules, growth factors, and other important mediators. It could be shown that connexins, the gap junction proteins, were located around cell nuclei, where they await their transport to the cell membrane. In addition, areas in which two cells formed gap junctions were found.

Ex vivo behaviour of human bone tumor endothelial cells

Cooperation between endothelial cells and bone in bone remodelling is well established. In contrast, bone microvasculature supporting the growth of primary tumors and metastasis is poorly understood. Several antiangiogenic agents have recently been undergoing trials, although an extensive body of clinical data and experimental research have proved that angiogenic pathways differ in each tumor type and stage. Here, for the first time, we characterize at the molecular and functional level tumor endothelial cells from human bone sarcomas at different stages of disease and with different histotypes. We selected a CD31⁺ subpopulation from biopsies that displayed the capability to grow as adherent cell lines without vascular endothelial growth factor (VEGF). Our findings show the existence in human primary bone sarcomas of highly proliferative endothelial cells expressing CD31, CD44, CD105, CD146 and CD90 markers. These cells are committed to develop capillary-like structures and colony formation units, and to produce nitric oxide. We believe that a better understanding of tumor vasculature could be a valid tool for the design of an efficacious antiangiogenic therapy as adjuvant treatment of sarcomas.

Genetic module and miRNome trait analyses reflect the distinct biological features of endothelial progenitor cells from different anatomic locations

Background

Endothelial progenitor cells (EPCs) play a fundamental role in post-natal vascular repair, yet EPCs from different anatomic locations possess unique biological properties. The underlying mechanisms are unclear.

Results

EPCs from CB expressed abundant genes involved in cell cycle, hypoxia signalling and blood vessel development, correlating with the phenotypes that CB-EPCs proliferated more rapidly, migrated faster, and formed tubule structure more efficiently. smRNA-seq further deciphered miRNome patterns in EPCs isolated from CB or PB: 54 miRNAs were enriched in CB-EPCs, while another 50 in PB-EPCs. Specifically, CB-EPCs expressed more angiogenic miRNAs such as miR-31, while PB-EPCs possessed more tumor suppressive miRNAs including miR-10a. Knocking down miR-31 levels in CB-EPCs suppressed cell migration and microtubule formation, while overexpressing miR-31 in PB-EPCs helped to recapitulate some of CB-EPC functions.

Conclusions

Our results show the foundation for a more detailed understanding of EPCs from different anatomic sources. Stimulating the expression of angiogenic microRNAs or genes in EPCs of low activity (such as those from patients with cardiovascular diseases) might allow the development of novel therapeutic strategies.