The Role of Synthetic Extracellular Matrices in Endothelial Progenitor Cell Homing for Treatment of Vascular Disease

Inflammatory Modulation of Polyethylene Glycol-AuNP for Regulation of the Neural Differentiation Capacity of Mesenchymal Stem Cells

A nanocomposite composed of polyethylene glycol (PEG) incorporated with various concentrations (~17.4, ~43.5, ~174 ppm) of gold nanoparticles (Au) was created to investigate its biocompatibility and biological performance in vitro and in vivo. First, surface topography and chemical composition was determined through UV-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), free radical scavenging ability, and water contact angle measurement. Additionally, the diameters of the PEG-Au nanocomposites were also evaluated through dynamic light scattering (DLS) assay. According to the results, PEG containing 43.5 ppm of Au demonstrated superior biocompatibility and biological properties for mesenchymal stem cells (MSCs), as well as superior osteogenic differentiation, adipocyte differentiation, and, particularly, neuronal differentiation. Indeed, PEG-Au 43.5 ppm induced better cell adhesion, proliferation and migration in MSCs. The higher expression of the SDF-1α/CXCR4 axis may be associated with MMPs activation and may have also promoted the differentiation capacity of MSCs. Moreover, it also prevented MSCs from apoptosis and inhibited macrophage and platelet activation, as well as reactive oxygen species (ROS) generation. Furthermore, the anti-inflammatory, biocompatibility, and endothelialization capacity of PEG-Au was measured in a rat model. After implanting the nanocomposites into rats subcutaneously for 4 weeks, PEG-Au 43.5 ppm was able to enhance the anti-immune response through inhibiting CD86 expression (M1 polarization), while also reducing leukocyte infiltration (CD45). Moreover, PEG-Au 43.5 ppm facilitated CD31 expression and anti-fibrosis ability. Above all, the PEG-Au nanocomposite was evidenced to strengthen the differentiation of MSCs into various cells, including fat, vessel, and bone tissue and, particularly, nerve cells. This research has elucidated that PEG combined with the appropriate amount of Au nanoparticles could become a potential biomaterial able to cooperate with MSCs for tissue regeneration engineering.

Anti-Inflammatory Fibronectin-AgNP for Regulation of Biological Performance and Endothelial Differentiation Ability of Mesenchymal Stem Cells

The engineering of vascular regeneration still involves barriers that need to be conquered. In the current study, a novel nanocomposite comprising of fibronectin (denoted as FN) and a small amount of silver nanoparticles (AgNP, ~15.1, ~30.2 or ~75.5 ppm) was developed and its biological function and biocompatibility in Wharton's jelly-derived mesenchymal stem cells (MSCs) and rat models was investigated. The surface morphology as well as chemical composition for pure FN and the FN-AgNP nanocomposites incorporating various amounts of AgNP were firstly characterized by atomic force microscopy (AFM), UV-Visible spectroscopy (UV-Vis), and Fourier-transform infrared spectroscopy (FTIR). Among the nanocomposites, FN-AgNP with 30.2 ppm silver nanoparticles demonstrated the best biocompatibility as assessed through intracellular ROS production, proliferation of MSCs, and monocytes activation. The expression levels of pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6, were also examined. FN-AgNP 30.2 ppm significantly inhibited pro-inflammatory cytokine expression compared to other materials, indicating superior performance of anti-immune response. Mechanistically, FN-AgNP 30.2 ppm significantly induced greater expression of vascular endothelial growth factor (VEGF) and stromal-cell derived factor-1 alpha (SDF-1α) and promoted the migration of MSCs through matrix metalloproteinase (MMP) signaling pathway. Besides, in vitro and in vivo studies indicated that FN-AgNP 30.2 ppm stimulated greater protein expressions of CD31 and von Willebrand Factor (vWF) as well as facilitated better endothelialization capacity than other materials. Furthermore, the histological tissue examination revealed the lowest capsule formation and collagen deposition in rat subcutaneous implantation of FN-AgNP 30.2 ppm. In conclusion, FN-AgNP nanocomposites may facilitate the migration and proliferation of MSCs, induce endothelial cell differentiation, and attenuate immune response. These finding also suggests that FN-AgNP may be a potential anti-inflammatory surface modification strategy for vascular biomaterials.

Intermittent hypoxia: Friend or foe on endothelial repair in mouse model

Aim of the study: Obstructive sleep apnea, which is characterized by intermittent hypoxia (IH), is a common respiratory disease. The aim of the present study was to explore the relationship between hypoxia and endothelial progenitor cell (EPC) function, and explain the role of IH in endothelial repair.Materials and methods: Peripheral blood mononuclear cells (PBMCs) were isolated from a mouse model of IH. The number of CD133⁺ kinase insert domain receptor (KDR)⁺, CD133⁺CD34⁺, CD34⁺KDR⁺ and ALDH^lowCD34⁺KDR⁺ EPCs was determined by flow cytometry. HIF-1α, stromal-derived factor-1 (SDF-1) α and VEGF were measured by ELISA. The proliferative ability of PBMCs was determined. EPC migration was assessed by Transwell assay and surface proteins by western blot analysis. EPCs were co-cultured with mouse brain endothelial cells and their angiogenic ability was analyzed.Results: The number of CD133⁺KDR⁺, CD133⁺CD34⁺ and CD34⁺KDR⁺ EPCs increased with IH ingravescence. The number of ALDH^lowCD34⁺KDR⁺ EPCs with mild IH stimulation was higher and gradually decreased in the moderate and severe IH groups. The release of HIF-1α, SDF-1α and VEGF in the serum increased with the increase in the degree of IH. In the mild IH treatment, the migration and angiogenesis of EPCs, as well as the expression of vascular endothelial growth factor receptor 2 and cysteine-X-cysteine receptor 4, were higher than those in the control group, but progressively decreased in the groups with moderate and severe IH.Conclusion: Increased levels of IH accelerated the increase in vasoactive factors in peripheral blood, thereby mobilizing a large number of EPCs. Increasing of IH diminished the mobilization, chemotactic and angiogenetic ability of EPCs.

IFN-I Mediates Dysfunction of Endothelial Progenitor Cells in Atherosclerosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease including the cardiovascular system. Atherosclerosis is the most common cardiovascular complication of SLE and a significant risk factor for morbidity and mortality. Vascular damage/protection mechanism in SLE patients is out of balance, caused by the cascade reaction among oxidative stress, proinflammatory cytokines, Neutrophil Extracellular Traps, activation of B cells and autoantibodies and abnormal T cells. As a precursor cell repairing vascular endothelium, endothelial progenitor cells (EPCs) belong to the protective mechanism and show the reduced number and impaired function in SLE. However, the pathological mechanism of EPCs dysfunction in SLE remains ill-defined. This paper reviews the latest SLE epidemiology and pathogenesis, discusses the changes in the number and function of EPCs in SLE, expounds the role of EPCs in SLE atherosclerosis, and provides new guidance and theoretical basis for exploring novel targets for SLE treatment.

Three-Dimensional Printed Stamps for the Fabrication of Patterned Microwells and High-Throughput Production of Homogeneous Cell Spheroids

Aggregation of cells into spheroids and organoids is a promising tool for regenerative medicine, cancer and cell biology, and drug discovery due to their recapitulation of the cell-cell and cell-matrix interactions found in vivo. Traditional approaches for the production of spheroids, such as the hanging drop method, are limited by the lack of reproducibility and the use of labor-intensive and time-consuming techniques. The need for high-throughput approaches allowing for the quick and reproducible formation of cell aggregates has driven the development of soft lithography techniques based on the patterning of microwells into nonadherent hydrogels. However, these methods are also limited by costly, labor-intensive, and multistep protocols that could impact the sterility of the process and efficiency of spheroid formation. In this study, we describe a one-step method for the fabrication of patterned nonadherent microwells into tissue culture plates using three-dimensional (3D) printed stamps and evaluate the production of cell spheroids of different sizes and cell sources. The generation of bone marrow-derived mesenchymal stromal cell and endothelial cell spheroids by the use of 3D printed stamps was superior in comparison with a widely used multistep mold technique, yielding spheroids of larger sizes and higher DNA content. The 3D stamps produced spheroids of more consistent diameter and DNA content when compared with other commercially available methods. These 3D printed stamps offer a tunable, simple, fast, and cost-effective approach for the production of reproducible spheroids and organoids for a wide range of applications.

Influencing factors of vascular endothelial function in patients with non-obstructive coronary atherosclerosis: a 1-year observational study

BACKGROUND

Endothelial dysfunction may play a key role in non-obstructive coronary artery atherosclerosis. Our study aimed to evaluate the vascular endothelial function and its influencing factors in patients with non-obstructive coronary artery atherosclerosis.

METHODS

A total of 131 consecutive patients with non-obstructive coronary artery atherosclerosis were enrolled. Flow-mediated dilatation (FMD) was measured at baseline and 1-year follow-up. Endothelial progenitor cells (EPCs) were counted by staining the fasting venous blood with antibodies against CD34 and vascular endothelial growth factor receptor 2.

RESULTS

Systolic blood pressure, pulse pressure and the levels of HbA1c in participants with baseline FMD < 6% (n = 65) were significantly higher than those with baseline FMD ≥ 6% (n = 66). Baseline FMD was negatively associated with EPC counts (r = - 0.199, P < 0.05) and systolic blood pressure (r = - 0.315, P < 0.01). The 1-year FMD was significantly increased compared to the baseline FMD [(9.31 ± 5.62) % vs (7.31 ± 5.26) %, P < 0.001]. Independent predictors of FMD improvement included elevated EPC counts (OR = 1.104, 95% CI: 1.047-1.165, P < 0.001) and decreased levels of serum creatinine (OR = 0.915, 95% CI: 0.843-0.993, P = 0.034).

CONCLUSIONS

Family history of premature cardiovascular diseases, hypertension, elevated systolic pressure, and HbA1c > 6.5% are independent risk factors for endothelial dysfunction in non-obstructive atherosclerotic patients. Elevated peripheral blood EPC counts and decreased levels of serum creatinine are independent predictors of endothelial function improvement.

Building a Total Bioartificial Heart: Harnessing Nature to Overcome the Current Hurdles

Engineering a bioartificial heart has become a possibility in part because of the regenerative medicine approaches to repairing or replacing damaged organs that have evolved over the past two decades. With the advent of inducible pluripotent stem cell technology, it is now possible to generate personalized cells that make the concept of autologous tissue engineering imaginable. Scaffolds that provide form, function, and biological cues to cells likewise potentially enable the engineering of biocompatible vascularized solid organs. Decellularized organs or tissue matrices retain organ complexity and structure at the macro and micro scales, contain biologically active molecules that support cell phenotype and function, and are vascularized allowing full thickness tissue generation. There is also dynamic reciprocity between the extracellular matrix and cells, which does not occur with synthetic scaffolds and allows both to evolve as functional need changes, making it a unique scaffold. Yet, building a whole heart from decellularized scaffolds and cells requires delivering hundreds of billions of multiple types of cardiac cells appropriately and providing a milieu where they can survive and mature. We propose a novel type of in vivo organ engineering utilizing pre-clinical models where decellularized hearts are heterotopically transplanted with the intent to harness the capability of the body to at least in part repopulate the scaffold. By adding load and electrical input, possibly via temporary mechanical assistance, we posit that vascular and parenchymal cell maturation can occur. In this study, we implanted porcine decellularized hearts acutely and chronically in living recipients in a heterotopic position. We demonstrated that the surgical procedure is critical to prevent coagulation and to increase graft patency. We also demonstrated that short-term implantation promotes endothelial cell adhesion to the vessel lumens and that long-term implantation also promotes tissue formation with evidence of cardiomyocytes and endothelial cells present within the graft. Utilizing endogenous repair capabilities of the recipient in response to a naked ECM, we allowed the transplanted scaffold to direct host cells-both organizationally and functionally. Thus, the scaffold provided necessary cues for cell organization and remodeling within the transplanted organ. Future work would involve culturing partially recellularized engineered organs in bioreactors where mechanical and electrical stimulation can be controlled to promote organ development and then transplanting these after a minimal level of maturation has been achieved.

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Functional engineered mesenchymal stem cells with fibronectin-gold composite coated catheters for vascular tissue regeneration

Vascularization of engineered tissues remains one of the key problems. Here, we described a novel approach to promote vascularization of engineered tissues using fibronectin (FN) incorporated gold nanoparticles (AuNP) coated onto catheters with mesenchymal stem cells (MSCs) for tissue engineering. We found that the FN-AuNP composite with 43.5 ppm of AuNP exhibited better biomechanical properties and thermal stability than pure FN. FN-AuNP composites promoted MSC proliferation and increased the biocompatibility. Mechanistically, vascular endothelial growth factor (VEGF) promoted MSC migration on FN-AuNP through the endothelial oxide synthase (eNOS)/metalloproteinase (MMP) signaling pathway. Vascular femoral artery tissues isolated from the implanted FN-AuNP-coated catheters with MSCs expressed substantial CD31 and alpha-smooth muscle actin (α-SMA), displayed higher antithrombotic activity, as well as better endothelialization ability than those coated with all other materials. These data suggested that the implantation of FN-AuNP-coated catheter with MSCs could be a novel strategy for vascular biomaterials applications.

Association of serum levels of antibodies against MMP1, CBX1, and CBX5 with transient ischemic attack and cerebral infarction

Transient ischemic attack (TIA) is a predictor for cerebral infarction (CI), and early diagnosis of TIA is extremely important for the prevention of CI. We set out to identify novel antibody biomarkers for TIA and CI, and detected matrix metalloproteinase 1 (MMP1), chromobox homolog 1 (CBX1), and chromobox homolog 5 (CBX5) as candidate antigens using serological identification of antigens by recombinant cDNA expression cloning (SEREX) and Western blotting to confirm the presence of serum antibodies against the antigens. Amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) revealed that serum antibody levels were significantly higher in patients with TIA or acute-phase CI (aCI) compared with healthy donors (P < 0.01). Spearman’s correlation analysis and multivariate logistic regression analysis demonstrated that levels of anti-MMP1, anti-CBX1, and anti-CBX5 antibodies were associated with age, cigarette-smoking habits, and blood pressure. Thus, serum levels of antibodies against MMP1, CBX1, and CBX5 could potentially serve as useful tools for diagnosing TIA and predicting the onset of aCI.

Alginate hydrogels of varied molecular weight distribution enable sustained release of sphingosine-1-phosphate and promote angiogenesis

Alginate hydrogels have been widely validated for controlled release of growth factors and cytokines, but studies exploring sustained release of small hydrophobic lipids are lacking. Sphingosine-1-phosphate (S1P), a bioactive lipid, is an appealing small molecule for inducing blood vessel formation in the context of ischemic conditions. However, there are numerous biological and engineering challenges associated with designing biomaterial systems for controlled release of this lipid. Thus, the objective of this study was to design an injectable, alginate hydrogel formulation that provides controlled release of S1P to establish locally sustained concentration gradients that promote neovascularization. Herein, we varied the molecular weight distribution of alginate polymers within the hydrogel to alter the resultant mechanical properties in a manner that provides control over S1P release. With increasing high molecular weight (HMW) content, the hydrogels exhibited stiffer material properties and released S1P at slower rates. Accordingly, S1P released from hydrogels with 100% HMW content led to enhanced directed migration of outgrowth endothelial cells and blood vessel development assessed using a chick chorioallantoic membrane assay as compared to hydrogels with less HMW content. Overall, this study describes how alginate hydrogels of varied molecular weight may be used to control S1P release kinetics for therapeutic applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 138-146, 2018.

Current Challenges in Translating Tissue-Engineered Heart Valves

Heart valve disease is a major health burden, treated by either valve repair or valve replacement, depending on the affected valve. Nearly 300,000 valve replacements are performed worldwide per year. Valve replacement is lifesaving, but not without complications. The in situ tissue-engineered heart valve is a promising alternative to current treatments, but the translation of this novel technology to the clinic still faces several challenges. These challenges originate from the variety encountered in the patient population, the conversion of an implant into a living tissue, the highly mechanical nature of the heart valve, the complex homeostatic tissue that has to be reached at the end stage of the regenerating heart valve, and all the biomaterial properties that can be controlled to obtain this tissue. Many of these challenges are multidimensional and multiscalar, and both the macroscopic properties of the complete heart valve and the microscopic properties of the patient’s cells interacting with the materials have to be optimal. Using newly developed in vitro models, or bioreactors, where variables of interest can be controlled tightly and complex mixtures of cell populations similar to those encountered in the regenerating valve can be cultured, it is likely that the challenges can be overcome.

Alginate-Chitosan Hydrogels Provide a Sustained Gradient of Sphingosine-1-Phosphate for Therapeutic Angiogenesis

Sphingosine-1-phosphate (S1P), a bioactive lipid, is a potent candidate for treatment of ischemic vascular disease. However, designing biomaterial systems for the controlled release of S1P to achieve therapeutic angiogenesis presents both biological and engineering challenges. Thus, the objective of this study was to design a hydrogel system that provides controlled and sustained release of S1P to establish local concentration gradients that promote neovascularization. Alginate hydrogels have been extensively studied and characterized for delivery of proangiogenic factors. We sought to explore if chitosan (0, 0.1, 0.5, or 1%) incorporation could be used as a means to control S1P release from alginate hydrogels. With increasing chitosan incorporation, hydrogels exhibited significantly denser pore structure and stiffer material properties. While 0.1 and 0.5% chitosan gels demonstrated slower respective release of S1P, release from 1% chitosan gels was similar to alginate gels alone. Furthermore, 0.5% chitosan gels induced greater sprouting and directed migration of outgrowth endothelial cells (OECs) in response to released S1P under hypoxia in vitro. Overall, this report presents a platform for a novel alginate-chitosan hydrogel of controlled composition and in situ gelation properties that can be used to control lipid release for therapeutic applications.

Isoprenaline Induces Periostin Expression in Gastric Cancer

PURPOSE

Periostin mediates critical steps in gastric cancer and is involved in various signaling pathways. However, the roles of periostin in promoting gastric cancer metastasis are not clear. The aim of this study was to investigate the relevance between periostin expression and gastric cancer progression and the role of stress-related hormones in the regulation of cancer development and progression.

MATERIALS AND METHODS

Normal, cancerous and metastatic gastric tissues were collected from patients diagnosed with advanced gastric cancer. The in vivo expression of periostin was evaluated by in situ hybridization and immunofluorescent staining. Meanwhile, human gastric adenocarcinoma cell lines MKN-45 and BGC-803 were used to detect the in vitro expression of periostin by using quantitative real-time polymerase chain reaction (PCR) and western blotting.

RESULTS

Periostin is expressed in the stroma of the primary gastric tumors and metastases, but not in normal gastric tissue. In addition, we observed that periostin is located mainly in pericryptal fibroblasts, but not in the tumor cells, and strongly correlated to the expression of α-smooth muscle actin (SMA). Furthermore, the distribution patterns of periostin were broader as the clinical staging of tumors progressed. We also identified a role of stress-related signaling in promoting cancer development and progression, and found that isoprenaline upregulated expression levels of periostin in gastric cancer cells.

CONCLUSION

These findings suggest that the distribution pattern of periostin was broader as the clinical staging of the tumor progressed and found that isoprenaline upregulated expression levels of periostin in gastric cancer cells.

Vascular endothelium - Gatekeeper of vessel health

The vascular endothelium is an interface between the blood stream and the vessel wall. Changes in this single cell layer of the artery wall are believed of primary importance in the pathogenesis of vascular disease/atherosclerosis. The endothelium responds to humoral, neural and especially hemodynamic stimuli and regulates platelet function, inflammatory responses, vascular smooth muscle cell growth and migration, in addition to modulating vascular tone by synthesizing and releasing vasoactive substances. Compromised endothelial function contributes to the pathogenesis of cardiovascular disease; endothelial 'dysfunction' is associated with risk factors, correlates with disease progression, and predicts cardiovascular events. Therapies for atherosclerosis have been developed, therefore, that are directed towards improving endothelial function.