Surface bound VEGF mimicking peptide maintains endothelial cell proliferation in the absence of soluble VEGF in vitro

Knockdown of hsa_circ_0005699 attenuates inflammation and apoptosis induced by ox-LDL in human umbilical vein endothelial cells through regulation of the miR-450b-5p/NFKB1 axis

Atherosclerosis (AS) remains the leading cause of mortality throughout the world, and vascular endothelial cell dysfunction is one of the key events leading to this pathology. In recent years, there has been an increased interest in the role of circulating RNAs in various diseases; these noncoding RNAs can regulate gene products by acting as microRNA (miR) sponges. Furthermore, it has been shown that foam cells exhibit high expression levels of hsa_circ_0005699 (circ_0005699); however, to the best of our knowledge, no previous study has investigated the role of circ_0005699 in the regulation of vascular endothelial function. The present study employed human umbilical vein endothelial cells (HUVECs), which have been widely used to study vascular endothelial cell function. In addition, apolipoprotein E (ApoE)-deficient mice were used, which have been shown to rapidly develop AS and are widely used as a model of this disease. Cellular and biochemical techniques were performed, including gene transfection and short hairpin RNA-mediated gene silencing for cell transfection, luciferase reporter gene assay to confirm predicted genes, Cell Counting Kit-8 assay and flow cytometry to assess cell viability and apoptosis, and reverse transcription-quantitative PCR and western blotting for detection of mRNA and protein expression. In the present study, the expression levels of circ_0005699 were increased by oxidized low-density lipoprotein in a time- and dose-dependent manner in HUVECs; this was also associated with increased apoptosis of these cells. In addition, the expression levels of circ_0005699 were elevated, along with increased levels of inflammatory cytokines, in ApoE-deficient mice. An RNA pull-down assay indicated that circ_0005699 can bind miR-450b-5p to decrease its expression, whereas silencing of circ_0005699 resulted in increased expression of miR-450b-5p. In addition, the online bioinformatics tool starBase predicted NFKB1 as a target gene of miR-450b-5p, which was further confirmed by the luciferase reporter gene assay. Notably, knockdown of circ_0005699 resulted in the increased survival of HUVECs, which was associated with decreased protein expression levels of NFKB1 and inflammatory cytokines. By contrast, the effects of circ-0005699 silencing on survival were reversed by miR-450b-5p inhibition or NFKB1 overexpression. In conclusion, knockdown of circ_0005699 may ameliorate endothelial cell injury through regulation of the miR-450b-5P/NFKB1 signaling axis.

Recent advance in treatment of atherosclerosis: Key targets and plaque-positioned delivery strategies

Atherosclerosis, a chronic inflammatory disease of vascular wall, is a progressive pathophysiological process with lipids oxidation/depositing initiation and innate/adaptive immune responses. The coordination of multi systems covering oxidative stress, dysfunctional endothelium, diseased lipid uptake, cell apoptosis, thrombotic and pro-inflammatory responding as well as switched SMCs contributes to plaque growth. In this circumstance, inevitably, targeting these processes is considered to be effective for treating atherosclerosis. Arriving, retention and working of payload candidates mediated by targets in lesion direct ultimate therapeutic outcomes. Accumulating a series of scientific studies and clinical practice in the past decades, lesion homing delivery strategies including stent/balloon/nanoparticle-based transportation worked as the potent promotor to ensure a therapeutic effect. The objective of this review is to achieve a very brief summary about the effective therapeutic methods cooperating specifical targets and positioning-delivery strategies in atherosclerosis for better outcomes.

Molecular-scale spatio-chemical control of the activating-inhibitory signal integration in NK cells

The role of juxtaposition of activating and inhibitory receptors in signal inhibition of cytotoxic lymphocytes remains strongly debated. The challenge lies in the lack of tools that allow simultaneous spatial manipulation of signaling molecules. To circumvent this, we produced a nanoengineered multifunctional platform with molecular-scale spatial control of ligands, which was applied to elucidate KIR2DL1-mediated inhibition of NKG2D signaling-receptors of natural killer cells. This platform was conceived by bimetallic nanodot patterning with molecular-scale registry, followed by a ternary functionalization with distinct moieties. We found that a 40-nm gap between activating and inhibitory ligands provided optimal inhibitory conditions. Supported by theoretical modeling, we interpret these findings as a consequence of the size mismatch and conformational flexibility of ligands in their spatial interaction. This highly versatile approach provides an important insight into the spatial mechanism of inhibitory immune checkpoints, which is essential for the rational design of future immunotherapies.

Osteopontin sequence modified mesoporous calcium silicate scaffolds to promote angiogenesis in bone tissue regeneration

Sufficient blood supply remains the key issue to be addressed for an optimal performance of implanted bone tissue engineering scaffolds. Host vessel invasion is limited to a depth of only several hundred micrometers from the scaffold/host interface. In this study, an osteopontin sequenced polypeptide SVVYGLR was grafted into/onto mesoporous calcium silicate (MCS) and then 3D-printed into scaffolds. The peptide motifs can be accessed on the scaffold surfaces and released as well. In vitro studies of human umbilical vein endothelial cells (HUVECs) indicated enhanced cell adhesion and vascular-like structure formation on MCS-SVVYGLR scaffolds. At the same time, human bone marrow stromal cells (hBMSCs) showed enhanced osteogenic differentiation capability and higher expression levels of angiogenic genes and proteins as well. The results of in vivo radial defect repair tests of rabbits showed that more tubular vessels formed throughout the whole MCS-SVVYGLR scaffolds, and therefore, a more homogeneous new bone formation pattern was obtained on MCS-SVVYGLR scaffolds instead of a peripheral bone growth pattern on pure MCS scaffolds by Micro-CT and tissue staining techniques over 3 months. Relative gene and protein expressions in PI3K/AKT and ERK1/2 pathways suggested that the SVVYGLR motif on the MCS scaffold surface could initiate the PI3K/AKT signaling pathway and up-regulate ERK1/2 expression, which positively stimulated VEGF expression, to improve angiogenesis.

Cell-Cell Adhesion-Driven Contact Guidance and Its Effect on Human Mesenchymal Stem Cell Differentiation

Contact guidance has been extensively explored using patterned adhesion functionalities that predominantly mimic cell-matrix interactions. Whether contact guidance can also be driven by other types of interactions, such as cell-cell adhesion, still remains a question. Herein, this query is addressed by engineering a set of microstrip patterns of (i) cell-cell adhesion ligands and (ii) segregated cell-cell and cell-matrix ligands as a simple yet versatile set of platforms for the guidance of spreading, adhesion, and differentiation of mesenchymal stem cells. It was unprecedently found that micropatterns of cell-cell adhesion ligands can induce contact guidance. Surprisingly, it was found that patterns of alternating cell-matrix and cell-cell strips also induce contact guidance despite providing a spatial continuum for cell adhesion. This guidance is believed to be due to the difference between the potencies of the two adhesions. Furthermore, patterns that combine the two segregated adhesion functionalities were shown to induce more human mesenchymal stem cell osteogenic differentiation than monofunctional patterns. This work provides new insight into the functional crosstalk between cell-cell and cell-matrix adhesions and, overall, further highlights the ubiquitous impact of the biochemical anisotropy of the extracellular environment on cell function.

Specific angiogenic peptide binding with injectable cardiac ECM collagen gel promotes the recovery of myocardial infarction in rat

Restoring blood supply is an effective way for the therapy of myocardial infarction (MI). It was reported a specific angiogenic peptide (VMP) derived from vascular endothelial growth factor (VEGF) could activate its receptor to mimic the biological activity of VEGF. In this study, in order to improve the local concentration in infarction region, a collagen-binding domain was synthesized with VMP to construct collagen binding domain (CBD)-VMP peptides. The fused CBD-VMP could bind specifically to collagen which was rich in cardiac extracellular matrix (c-ECM), without impacting the biological activity of VMP peptides. When the CBD-VMP peptides loaded on collagen scaffold and implanted into the rats subcutaneously, significant vascularization was observed. Then, CBD-VMP peptides binding with injectable c-ECM injected into the MI rat by intramuscular administration, significant blood vessels regeneration, and decrease of cell apoptosis were observed, that corelated with the recovery of cardiac function. It might be an alternative promising strategy for the clinical application of MI.

Microchannel Molding Combined with Layer-by-Layer Approach for the Formation of Three-Dimensional Tube-like Structures by Endothelial Cells

The development of a functional in vitro model for microcirculation is an unresolved challenge, with major impact for the creation and regeneration of organs in the tissue engineering. The absence of prevascularized engineered tissues limits enormously their efficacy and integration. Therefore, in this study, the in vitro formation of tubular-like structures with human umbilical vein endothelial cells (HUVECs) is investigated thanks to three-dimensional polycarbonate (PC) microchannel (μCh) scaffolds, surface biofunctionalized with hyaluronic acid/chitosan (HA/CHI) layer-by-layer (LbL) films grafted with adhesive (RGD) and angiogenic (SVV and QK) peptides, alone and in combination. The importance of this work lies in the formation of capillaries in the order of tens of μm, developing spontaneous microvessels, without the complexity of microfluidic approaches, and in a short time-scale. Ellipsometry, confocal laser scanning microscopy, and fluorospectrometry are used to characterize the biofunctionalized microchannels. PC-μCh scaffolds functionalized with (HA/CHI)_12.5 film (PC-LbL) and further grafted with RGD and QK peptides (PC-RGD+QK) or with RGD and SVV peptides (PC-RGD+SVV) are then tested for in vitro blood vessel formation. These assays evidence a rapid formation of tubular-like structures after 2 h of incubation. Moreover, a coculture system involving HUVECs and human pericytes derived from placenta (hPCs-PL) stabilizes the tubes for a longer time.

Advanced Materials and Devices for the Regulation and Study of NK Cells

Natural Killer (NK) cells are innate lymphocytes that contribute to immune protection by cytosis, cytokine secretion, and regulation of adaptive responses of T cells. NK cells distinguish between healthy and ill cells, and generate a cytotoxic response, being cumulatively regulated by environmental signals delivered through their diverse receptors. Recent advances in biomaterials and device engineering paved the way to numerous artificial microenvironments for cells, which produce synthetic signals identical or similar to those provided by the physiological environment. In this paper, we review recent advances in materials and devices for artificial signaling, which have been applied to regulate NK cells, and systematically study the role of these signals in NK cell function.