Coronary stents with inducible VEGF/HGF-secreting UCB-MSCs reduced restenosis and increased re-endothelialization in a swine model. Exp Mol Med. 2018;50:114. [PMID: 30174328 PMCID: PMC6119684 DOI: 10.1038/s12276-018-0143-9]

Development of an In Vitro Blood Vessel Model Using Autologous Endothelial Cells Generated from Footprint-Free hiPSCs to Analyze Interactions of the Endothelium with Blood Cell Components and Vascular Implants

Cardiovascular diseases are the leading cause of death globally. Vascular implants, such as stents, are required to treat arterial stenosis or dilatation. The development of innovative stent materials and coatings, as well as novel preclinical testing strategies, is needed to improve the bio- and hemocompatibility of current stents. In this study, a blood vessel-like polydimethylsiloxane (PDMS) model was established to analyze the interaction of an endothelium with vascular implants, as well as blood-derived cells, in vitro. Using footprint-free human induced pluripotent stem cells (hiPSCs) and subsequent differentiation, functional endothelial cells (ECs) expressing specific markers were generated and used to endothelialize an artificial PDMS lumen. The established model was used to demonstrate the interaction of the created endothelium with blood-derived immune cells, which also allowed for real-time imaging. In addition, a stent was inserted into the endothelialized lumen to analyze the surface endothelialization of stents. In the future, this blood vessel-like model could serve as an in vitro platform to test the influence of vascular implants and coatings on endothelialization and to analyze the interaction of the endothelium with blood cell components.

Comparison of Gelatin/Polylysine- and Silk Fibroin/SDF-1α-Coated Mesenchymal Stem Cell-Seeded Intracranial Stents

Endothelialization of the aneurysmal neck is essential for aneurysm healing after endovascular treatment. Mesenchymal stem cell (MSC)-seeded stents can promote aneurysm repair. The biological effects of coated and uncoated nitinol intracranial stents seeded with MSCs on vascular cells and macrophage proliferation and inflammation are investigated. Two stent coatings that exert pro-aggregation effects on MSCs via different mechanisms are examined: gelatin/polylysine (G/PLL), which enhances cell adhesion, and silk fibroin/SDF-1α (SF/SDF-1α), which enhances chemotaxis. The aim is to explore the feasibility of MSC-seeded coated stents in the treatment of intracranial aneurysms. The G/PLL coating provides the highest cytocompatibility and blood compatibility substrate for MSCs and vascular cells and promotes cell adhesion and proliferation. Moreover, it enhances MSC secretion and regulation of vascular cell and macrophage proliferation and chemotaxis. Although the SF/SDF-1α coating promotes MSC secretion and vascular cell chemotaxis, it induces a greater degree of macrophage proliferation, chemotaxis, and secretion of pro-inflammatory factors. MSC-seeded stents coated with G/PLL may benefit stent surface endothelialization and reduce the inflammatory response after endovascular treatment of intracranial aneurysm. These effects may improve aneurysm healing and increase the cure rate.

The path to a hemocompatible cardiovascular implant: Advances and challenges of current endothelialization strategies

Cardiovascular (CV) implants are still associated with thrombogenicity due to insufficient hemocompatibility. Endothelialization of their luminal surface is a promising strategy to increase their hemocompatibility. In this review, we provide a collection of research studies and review articles aiming to summarize the recent efforts on surface modifications of CV implants, including stents, grafts, valves, and ventricular assist devises. We focus in particular on the implementation of micrometer or nanoscale surface modifications, physical characteristics of known biomaterials (such as wetness and stiffness), and surface morphological features (such as gratings, fibers, pores, and pits). We also review how biomechanical signals originating from the endothelial cell for surface interaction can be directed by topography engineering approaches toward the survival of the endothelium and its long-term adaptation. Finally, we summarize the regulatory and economic challenges that may prevent clinical implementation of endothelialized CV implants.

Intra-arterial injection of mesenchymal stem cells to accelerate neointima formation after endovascular stenting in a rabbit model

OBJECTIVE

Delayed neointima formation over a neurovascular stent is associated with thrombotic complications that can lead to stroke. The purpose of this study was to evaluate whether an intra-arterial injection of mesenchymal stem cells (MSCs) after stent placement leads to improved neointima and reduced thrombus formation over the device.

METHODS

Solitaire stents were placed into the aortas of rabbits that were divided into MSC and control groups. The MSC group received an intra-arterial injection of MSCs through the same microcatheter used for stent deployment. Optical coherence tomography (OCT) was used to evaluate and compare neointima and thrombus formation in a blinded fashion. Explanted specimens were also imaged with scanning electron microscopy (SEM) and evaluated by observers blinded to group allocation using an endothelialization scoring system.

RESULTS

The 3-day MSC group was similar to the 7-day controls in terms of stent strut coverage ratio and maximum neointimal thickness, but these values were significantly higher than the 3-day control group based on a hierarchical mixed-effects linear regression analysis. SEM revealed a significantly higher endothelialization score for the MSC group compared with controls at the same time point. There was no difference in thrombus formation between any of the groups.

CONCLUSIONS

The intra-arterial injection of MSCs after endovascular stenting accelerated early neointima formation but had no effect on thrombus formation in this study. Larger studies are required to verify these findings and determine the durability and mechanism of this effect.

Nanostructured Modifications of Titanium Surfaces Improve Vascular Regenerative Properties of Exosomes Derived from Mesenchymal Stem Cells: Preliminary In Vitro Results

(1) Background: Implantation of metal-based scaffolds is a common procedure for treating several diseases. However, the success of the long-term application is limited by an insufficient endothelialization of the material surface. Nanostructured modifications of metal scaffolds represent a promising approach to faster biomaterial osteointegration through increasing of endothelial commitment of the mesenchymal stem cells (MSC). (2) Methods: Three different nanotubular Ti surfaces (TNs manufactured by electrochemical anodization with diameters of 25, 80, or 140 nm) were seeded with human MSCs (hMSCs) and their exosomes were isolated and tested with human umbilical vein endothelial cells (HUVECs) to assess whether TNs can influence the secretory functions of hMSCs and whether these in turn affect endothelial and osteogenic cell activities in vitro. (3) Results: The hMSCs adhered on all TNs and significantly expressed angiogenic-related factors after 7 days of culture when compared to untreated Ti substrates. Nanomodifications of Ti surfaces significantly improved the release of hMSCs exosomes, having dimensions below 100 nm and expressing CD63 and CD81 surface markers. These hMSC-derived exosomes were efficiently internalized by HUVECs, promoting their migration and differentiation. In addition, they selectively released a panel of miRNAs directly or indirectly related to angiogenesis. (4) Conclusions: Preconditioning of hMSCs on TNs induced elevated exosomes secretion that stimulated in vitro endothelial and cell activity, which might improve in vivo angiogenesis, supporting faster scaffold integration.

Cardiomyocyte Death and Genome-Edited Stem Cell Therapy for Ischemic Heart Disease

Massive death of cardiomyocytes is a major feature of cardiovascular diseases. Since the regenerative capacity of cardiomyocytes is limited, the regulation of their death has been receiving great attention. The cell death of cardiomyocytes is a complex mechanism that has not yet been clarified, and it is known to appear in various forms such as apoptosis, necrosis, etc. In ischemic heart disease, the apoptosis and necrosis of cardiomyocytes appear in two types of programmed forms (intrinsic and extrinsic pathways) and they account for a large portion of cell death. To repair damaged cardiomyocytes, diverse stem cell therapies have been attempted. However, despite the many positive effects, the low engraftment and survival rates have clearly limited the application of stem cells in clinical therapy. To solve these challenges, the introduction of the desired genes in stem cells can be used to enhance their capacity and improve their therapeutic efficiency. Moreover, as genome engineering technologies have advanced significantly, safer and more stable delivery of target genes and more accurate deletion of genes have become possible, which facilitates the genetic modification of stem cells. Accordingly, stem cell therapy for damaged cardiac tissue is expected to further improve. This review describes myocardial cell death, stem cell therapy for cardiac repair, and genome-editing technologies. In addition, we introduce recent stem cell therapies that incorporate genome-editing technologies in the myocardial infarction model. Graphical Abstract.

Coatings in Decellularized Vascular Scaffolds for the Establishment of a Functional Endothelium: A Scoping Review of Vascular Graft Refinement

Developments in tissue engineering techniques have allowed for the creation of biocompatible, non-immunogenic alternative vascular grafts through the decellularization of existing tissues. With an ever-growing number of patients requiring life-saving vascular bypass grafting surgeries, the production of functional small diameter decellularized vascular scaffolds has never been more important. However, current implementations of small diameter decellularized vascular grafts face numerous clinical challenges attributed to premature graft failure as a consequence of common failure mechanisms such as acute thrombogenesis and intimal hyperplasia resulting from insufficient endothelial coverage on the graft lumen. This review summarizes some of the surface modifying coating agents currently used to improve the re-endothelialization efficiency and endothelial cell persistence in decellularized vascular scaffolds that could be applied in producing a better patency small diameter vascular graft. A comprehensive search yielding 192 publications was conducted in the PubMed, Scopus, Web of Science, and Ovid electronic databases. Careful screening and removal of unrelated publications and duplicate entries resulted in a total of 16 publications, which were discussed in this review. Selected publications demonstrate that the utilization of surface coating agents can induce endothelial cell adhesion, migration, and proliferation therefore leads to increased re-endothelialization efficiency. Unfortunately, the large variance in methodologies complicates comparison of coating effects between studies. Thus far, coating decellularized tissue gave encouraging results. These developments in re-endothelialization could be incorporated in the fabrication of functional, off-the-shelf alternative small diameter vascular scaffolds.

Endothelial Cell-Mediated Gene Delivery for In Situ Accelerated Endothelialization of a Vascular Graft

As an urgently needed device for vascular diseases, the small-diameter vascular graft is limited by high thrombogenicity in clinical applications. Rapid endothelialization is a promising approach to construct an antithrombogenic inner surface of the vascular graft. The main bottleneck for rapid endothelialization is the adhesion, migration, and proliferation of endothelial cells (ECs) in situ of the small-diameter vascular graft. Herein, we innovatively fabricated an intelligent gene delivery small-caliber vascular graft based on electrospun poly(lactic acid-co-caprolactone) and gelatin for rapid in situ endothelialization. The graft surface was co-modified with EC adhesive peptide of Arg-Glu-Asp-Val (REDV) and responsive gene delivery system. REDV can selectively adhere ECs onto the graft surface; subsequently, the overexpressed matrix metalloproteinase by ECs can effectively cleave the linker peptide GPQGIWGQ-C; and finally, the gene complexes were intelligently and enzymatically released from the graft surface, and thereby, the gene can efficiently transfect ECs. Importantly, this enzymatically releasing gene surface has been proven to be safe and temporarily stable in blood flow owing to the biotin-avidin interaction to immobilize gene complexes on the inner surface of vascular grafts through the GPQGIWGQ-C peptide linker. It has the advantage of specifically adhering the ECs to the surface and smartly transfecting them with high transfection efficiency. The co-modified surface has been demonstrated to accelerate the luminal endothelialization in vivo, which might be attributed to the synergistic effect of REDV and effective gene transfection. Particularly, the intelligent and responsive gene release surface will open a new avenue to enhance the endothelialization of blood-contacting devices.

Recent Developed Strategies for Enhancing Chondrogenic Differentiation of MSC: Impact on MSC-Based Therapy for Cartilage Regeneration

Articular cartilage is susceptible to damage, but its self-repair is hindered by its avascular nature. Traditional treatment methods are not able to achieve satisfactory repair effects, and the development of tissue engineering techniques has shed new light on cartilage regeneration. Mesenchymal stem cells (MSCs) are one of the most commonly used seed cells in cartilage tissue engineering. However, MSCs tend to lose their multipotency, and the composition and structure of cartilage-like tissues formed by MSCs are far from those of native cartilage. Thus, there is an urgent need to develop strategies that promote MSC chondrogenic differentiation to give rise to durable and phenotypically correct regenerated cartilage. This review provides an overview of recent advances in enhancement strategies for MSC chondrogenic differentiation, including optimization of bioactive factors, culture conditions, cell type selection, coculture, gene editing, scaffolds, and physical stimulation. This review will aid the further understanding of the MSC chondrogenic differentiation process and enable improvement of MSC-based cartilage tissue engineering.

The Combined Contribution of Vascular Endothelial Cell Migration and Adhesion to Stent Re-endothelialization

Coronary stent placement inevitably causes mechanical damage to the endothelium, leading to endothelial denudation and in-stent restenosis (ISR). Re-endothelialization depends mainly on the migration of vascular endothelial cells (VECs) adjacent to the damaged intima, as well as the mobilization and adhesion of circulating VECs. To evaluate the combined contribution of VEC migration and adhesion to re-endothelialization under flow and the influence of stent, in vitro models were constructed to simulate various endothelial denudation scales (2 mm/5 mm/10 mm) and stent deployment depths (flat/groove/bulge). Our results showed that (1) in 2 mm flat/groove/bulge models, both VEC migration and adhesion combined completed the percentage of endothelial recovery about 27, 16, and 12%, and migration accounted for about 21, 15, and 7%, respectively. It was suggested that the flat and groove models were in favor of VEC migration. (2) With the augmentation of the injury scales (5 and 10 mm), the contribution of circulating VEC adhesion on endothelial repair increased. Taken together, endothelial restoration mainly depended on the migration of adjacent VECs when the injury scale was 2 mm. The adhered cells contributed to re-endothelialization in an injury scale-dependent way. This study is helpful to provide new enlightenment for surface modification of cardiovascular implants.

Strategies to Overcome the Barrier of Ischemic Microenvironment in Cell Therapy of Cardiovascular Disease

The transplantation of various immune cell types are promising approaches for the treatment of ischemic cardiovascular disease including myocardial infarction (MI) and peripheral arterial disease (PAD). Major limitation of these so-called Advanced Therapy Medicinal Products (ATMPs) is the ischemic microenvironment affecting cell homeostasis and limiting the demanded effect of the transplanted cell products. Accordingly, different clinical and experimental strategies have been evolved to overcome these obstacles. Here, we give a short review of the different experimental and clinical strategies to solve these issues due to ischemic cardiovascular disease.

Prospects for the therapeutic development of umbilical cord blood-derived mesenchymal stem cells

Umbilical cord blood (UCB) is a primitive and abundant source of mesenchymal stem cells (MSCs). UCB-derived MSCs have a broad and efficient therapeutic capacity to treat various diseases and disorders. Despite the high latent self-renewal and differentiation capacity of these cells, the safety, efficacy, and yield of MSCs expanded for ex vivo clinical applications remains a concern. However, immunomodulatory effects have emerged in various disease models, exhibiting specific mechanisms of action, such as cell migration and homing, angiogenesis, anti-apoptosis, proliferation, anti-cancer, anti-fibrosis, anti-inflammation and tissue regeneration. Herein, we review the current literature pertaining to the UCB-derived MSC application as potential treatment strategies, and discuss the concerns regarding the safety and mass production issues in future applications.

MicroRNA‑24 attenuates diabetic vascular remodeling by suppressing the NLRP3/caspase‑1/IL‑1β signaling pathway

Vascular remodeling plays an important role in the pathogenesis of diabetic cardiovascular complications. Previous published research has indicated that microRNA-24 (miR-24) is involved in diabetic vascular remodeling, but the underlying molecular mechanisms have yet to be fully elucidated. The aim of the present study was to investigate whether adenovirus-mediated miR-24 overexpression can suppress the NOD-like receptor family pyrin domain-containing 3 (NLRP3)-related inflammatory signaling pathway and attenuate diabetic vascular remodeling. The carotid arteries of diabetic rats were harvested and prepared for analysis. Reverse transcription-quantitative PCR and western blotting assays were used to detect the expressions of related mRNAs and proteins. Morphological examinations, including hematoxylin and eosin, immunohistochemical and Masson’s trichrome staining, were also performed. The results of the present study demonstrated that miR-24 upregulation suppressed neointimal hyperplasia and accelerated reendothelialization in the injured arteries, lowered the expression of NLRP3, apoptosis-associated speck-like protein, caspase-1, proliferating cell nuclear antigen, CD45, interleukin (IL)-1β, IL-18 and tumor necrosis factor-α, and increased the expression of CD31, smooth muscle (SM) α-actin and SM-myosin heavy chain. These data indicated that miR-24 overexpression can attenuate vascular remodeling in a diabetic rat model through suppressing the NLRP3/caspase-1/IL-1β signaling pathway.

Transplantation of hMSCs Genome Edited with LEF1 Improves Cardio-Protective Effects in Myocardial Infarction

Stem cell-based therapy is one of the most attractive approaches to ischemic heart diseases, such as myocardial infarction (MI). We evaluated the cardio-protective effects of the human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) stably expressing lymphoid enhancer-binding factor 1 (LEF1; LEF1/hUCB-MSCs) in a rat model of MI. LEF1 overexpression in hUCB-MSCs promoted cell-proliferation and anti-apoptotic effects in hypoxic conditions. For the application of its therapeutic effects in vivo, the LEF1 gene was introduced into an adeno-associated virus integration site 1 (AAVS1) locus, known as a safe harbor site on chromosome 19 by CRISPR/Cas9-mediated gene integration in hUCB-MSCs. Transplantation of LEF1/hUCB-MSCs onto the infarction region in the rat model significantly improved overall survival. The cardio-protective effect of LEF1/hUCB-MSCs was proven by echocardiogram parameters, including greatly improved left-ventricle ejection fraction (EF) and fractional shortening (FS). Moreover, histology and immunohistochemistry successfully presented reduced MI region and fibrosis by LEF1/hUCB-MSCs. We found that these overall positive effects of LEF1/hUCB-MSCs are attributed by increased proliferation and survival of stem cells in oxidative stress conditions and by the secretion of various growth factors by LEF1. In conclusion, this study suggests that the stem cell-based therapy, conjugated with genome editing of transcription factor LEF1, which promotes cell survival, could be an effective therapeutic strategy for cardiovascular disease.

CD276 (B7-H3) Maintains Proliferation and Regulates Differentiation in Angiogenic Function in Late Endothelial Progenitor Cells

Endothelial progenitor cells (EPCs) provide an important source of recovery from blood vessel dysfunction. Late EPCs (LEPCs) are circulating blood cells that are capable of promoting vascular repair. Using transcriptome analysis, we identified distinctive LEPC profiles and found that CD276 (B7-H3) mRNA is strongly expressed in LEPCs. CD276 protein is present abundantly on the cell surface of LEPC when analyzed by fluorescence-activated cell sorter and immunocytochemistry. CD276, a B7 family member, is a type I transmembrane glycoprotein. The role of CD276 in LEPCs remains unknown. CD276 knockdown by lentivirus transduction in LEPCs significantly decreased proliferation and increased apoptosis of LEPCs in vitro. After CD276 silencing, the cell cycle of LEPCs was prone to remain at the G0/G1 phase, and the cell migration rates as well as transwell and wound-healing migration were decreased. CD276 knockdown in LEPCs increased the G1 phase regulators cyclin D2/D3/E1-cyclin-dependent kinases (CDK2/4/6), but decreased the S-G2-M phase regulators cyclin A/B-CDK1. However, LEPCs with CD276 knockdown resulted in increased tube formation in vitro and angiogenesis in a Matrigel plug assay in vivo. FoxC1/C2, an upstream signal of Notch in arterial cell proliferation, and Hey1/2, which is known to promote arterial differentiation in the vasculature, were upregulated in CD276 knockdown LEPCs. In LEPCS, CD276 has a positive effect on proliferation and migration of endothelial cells, but negative effects on angiogenesis, particularly endothelial cell differentiation. Our data indicate, for therapeutic purpose, that CD276 can be used to acquire and maintain cell populations of LEPCs and blocking CD276 will promote angiogenetic differentiation. We found that CD276 (B7-H3) is enriched on the cell membrane of LEPCs. CD276 knockdown reduced proliferation and migration of LEPCs by increasing cell cycle inhibitors such as p21^cip1 and pRb and decreasing pErk1/2 and pAkt but promoted angiogenesis and endothelial cell differentiation by elevating vascular endothelial growth factor-vascular endothelial growth factor receptor 1 and p-p38. Stem Cells 2019;37:382-394.