Smooth muscle cells differentiated from reprogrammed embryonic lung fibroblasts through DKK3 signaling are potent for tissue engineering of vascular grafts

The Role of Progenitor Cells in the Pathogenesis of Arteriosclerosis

The increasing incidence of arteriosclerosis has become a significant global health burden. Arteriosclerosis is characterized by the thickening and hardening of arterial walls, which can lead to the narrowing or complete blockage of blood vessels. However, the pathogenesis of the disease remains incompletely understood. Recent research has shown that stem and progenitor cells found in the bone marrow and local vessel walls play a role in the development of arteriosclerosis by differentiating into various types of vascular cells, including endothelial cells, smooth muscle cells, fibroblasts, and inflammatory cells. This review aims to provide a comprehensive understanding of the role of stem and progenitor cells in the pathogenesis of arteriosclerosis, shedding light on the underlying mechanisms and potential therapeutic approaches for this disease.

Challenges and Strategies for Endothelializing Decellularized Small-Diameter Tissue-Engineered Vessel Grafts

Vascular diseases are the leading cause of ischemic necrosis in tissues and organs, necessitating using vascular grafts to restore blood supply. Currently, small vessels for coronary artery bypass grafts are unavailable in clinical settings. Decellularized small-diameter tissue-engineered vessel grafts (SD-TEVGs) hold significant potential. However, they face challenges, as simple implantation of decellularized SD-TEVGs in animals leads to thrombosis and calcification due to incomplete endothelialization. Consequently, research and development focus has shifted toward enhancing the endothelialization process of decellularized SD-TEVGs. This paper reviews preclinical studies involving decellularized SD-TEVGs, highlighting different strategies and their advantages and disadvantages for achieving rapid endothelialization of these vascular grafts. Methods are analyzed to improve the process while addressing potential shortcomings. This paper aims to contribute to the future commercial viability of decellularized SD-TEVGs.

The predictive value of serum Dickkopf-1, Dickkopf-3 level to coronary artery disease and acute coronary syndrome

BACKGROUND

Previous studies have already confirmed the association between Dickkopf (Dkk) protein and the occurrence and progression of atherosclerosis. However, there is limited clinical evidence regarding the serum levels of Dickkopf-1 (Dkk1) and Dickkopf-3 (Dkk3) in relation to atherosclerotic cardiovascular disease (ASCVD), particularly acute coronary syndrome (ACS).

MATERIALS AND METHODS

A total of 88 healthy volunteers and 280 patients with coronary artery disease (CAD) undergoing coronary angiography for angina between October 2021 and October 2022, including 96 cases of stable angina (SA), 96 of unstable angina (UA) and 88 of acute myocardial infarction (AMI) were included finally. The serum concentrations of Dkk1 and Dkk3 were measured using electrochemiluminescence of Meso Scale Discovery. The predictive value of single or combined application of serum Dkk1 and Dkk3 in CAD and ACS were evaluated.

RESULTS

The serum levels of Dkk1 were significantly higher in the SA group, UA group, and AMI group compared to the control group. Multivariable logistic regression analysis demonstrated that elevated serum Dkk1 levels were independent predictive factors for increased risk of CAD and ACS (OR = 1.027, 95%CI = 1.019-1.034, p < 0.001; OR = 1.045, 95%CI = 1.028-1.053, p < 0.001, respectively). Receiver operating characteristic curve (ROC) analysis showed that the optimal cutoff value of serum Dkk1 for predicting ACS was 205 ng/dl, with a sensitivity of 82.6% and specificity of 96.6%. The area under the curve (AUC) was 0.930 (95%CI: 0.899-0.961, p < 0.001). Regarding Dkk3, serum Dkk3 levels were elevated in CAD patients compared to the healthy control group, and significantly higher in ACS patients compared to SA patients. Serum Dkk3 was significantly associated with increased risk of CAD and ACS (OR = 1.131, 95%CI = 1.091-1.173, p < 0.001; OR = 1.201, 95%CI = 1.134-1.271, p < 0.001, respectively). ROC curve analysis showed that the optimal cutoff value of serum Dkk3 for predicting ACS was 50.82 ng/ml, with a sensitivity of 85.9% and specificity of 87.5%. The AUC was 0.925 (95%CI: 0.894-0.956, p < 0.001). When serum Dkk1 and Dkk3 are combined as predictive factors for ACS, the AUC was 0.975.

CONCLUSION

Serum levels of Dkk1 and Dkk3 are significantly associated with an increased risk of CAD and ACS, and they possess predictive value for CAD and ACS. The combination of serum Dkk1 and Dkk3 is a superior predictive factor for CAD and ACS.

Direct cellular reprogramming and transdifferentiation of fibroblasts on wound healing-Fantasy or reality?

Induced pluripotent stem cell (iPSC) technology is one of the de novo approaches in regeneration medicine and has led to new research applications for wound healing in recent years. Fibroblasts have attracted wide attention as the first cell line used for differentiation into iPSCs. Researchers have found that fibroblasts can be induced into different types of cells in variable mediums or microenvironments. This indicates the potential "stem" characteristics of fibroblasts in terms of direct cellular reprogramming compared with the iPSC detour. In this review, we described the morphology and biological function of fibroblasts. The stem cell characteristics and activities of fibroblasts, including transdifferentiation into myofibroblasts, osteogenic cells, chondrogenic cells, neurons, and vascular tissue, are discussed. The biological values of fibroblasts are then briefly reviewed. Finally, we discussed the potential applications of fibroblasts in clinical practice.

Differentiation and Engineering of Human Stem Cells for Smooth Muscle Generation

Cardiovascular diseases are responsible for 31% of global deaths and are considered the main cause of death and disability worldwide. Stem cells from various sources have become attractive options for a range of cell-based therapies for smooth muscle tissue regeneration. However, for efficient myogenic differentiation, the stem cell characteristics, cell culture conditions, and their respective microenvironments need to be carefully assessed. This review covers the various approaches involved in the regeneration of vascular smooth muscles by conditioning human stem cells. This article delves into the different sources of stem cells used in the generation of myogenic tissues, the role of soluble growth factors, use of scaffolding techniques, biomolecular cues, relevance of mechanical stimulation, and key transcription factors involved, aimed at inducing myogenic differentiation. Impact statement The review article's main goal is to discuss the recent advances in the field of smooth muscle tissue regeneration. We look at various cell sources, growth factors, scaffolds, mechanical stimuli, and factors involved in smooth muscle formation. These stem cell-based approaches for vascular muscle formation will provide various options for cell-based therapies with long-term beneficial effects on patients.

Correlation between stem cell molecular phenotype and atherosclerotic plaque neointima formation and analysis of stem cell signal pathways

Vascular stem cells exist in the three-layer structure of blood vessel walls and play an indispensable role in angiogenesis under physiological conditions and vascular remodeling under pathological conditions. Vascular stem cells are mostly quiescent, but can be activated in response to injury and participate in endothelial repair and neointima formation. Extensive studies have demonstrated the differentiation potential of stem/progenitor cells to repair endothelium and participate in neointima formation during vascular remodeling. The stem cell population has markers on the surface of the cells that can be used to identify this cell population. The main positive markers include Stem cell antigen-1 (Sca1), Sry-box transcription factor 10 (SOX10). Stromal cell antigen 1 (Stro-1) and Stem cell growth factor receptor kit (c-kit) are still controversial. Different parts of the vessel have different stem cell populations and multiple markers. In this review, we trace the role of vascular stem/progenitor cells in the progression of atherosclerosis and neointima formation, focusing on the expression of stem cell molecular markers that occur during neointima formation and vascular repair, as well as the molecular phenotypic changes that occur during differentiation of different stem cell types. To explore the correlation between stem cell molecular markers and atherosclerotic diseases and neointima formation, summarize the differential changes of molecular phenotype during the differentiation of stem cells into smooth muscle cells and endothelial cells, and further analyze the signaling pathways and molecular mechanisms of stem cells expressing different positive markers participating in intima formation and vascular repair. Summarizing the limitations of stem cells in the prevention and treatment of atherosclerotic diseases and the pressing issues that need to be addressed, we provide a feasible scheme for studying the signaling pathways of vascular stem cells involved in vascular diseases.

Toward the next generation of vascularized human neural organoids

Thanks to progress in the development of three-dimensional (3D) culture technologies, human central nervous system (CNS) development and diseases have been gradually deciphered by using organoids derived from human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs). Selforganized neural organoids (NOs) have been used to mimic morphogenesis and functions of specific organs in vitro. Many NOs have been reproduced in vitro, such as those mimicking the human brain, retina, and spinal cord. However, NOs fail to capitulate to the maturation and complexity of in vivo neural tissues. The persistent issues with current NO cultivation protocols are inadequate oxygen supply and nutrient diffusion due to the absence of vascular networks. In vivo, the developing CNS is interpenetrated by vasculature that not only supplies oxygen and nutrients but also provides a structural template for neuronal growth. To address these deficiencies, recent studies have begun to couple NO culture with bioengineering techniques and methodologies, including genetic engineering, coculture, multidifferentiation, microfluidics and 3D bioprinting, and transplantation, which might promote NO maturation and create more functional NOs. These cutting-edge methods could generate an ever more reliable NO model in vitro for deciphering the codes of human CNS development, disease progression, and translational application. In this review, we will summarize recent technological advances in culture strategies to generate vascularized NOs (vNOs), with a special focus on cerebral- and retinal-organoid models.

Updated Perspectives on Direct Vascular Cellular Reprogramming and Their Potential Applications in Tissue Engineered Vascular Grafts

Cardiovascular disease is a globally prevalent disease with far-reaching medical and socio-economic consequences. Although improvements in treatment pathways and revascularisation therapies have slowed disease progression, contemporary management fails to modulate the underlying atherosclerotic process and sustainably replace damaged arterial tissue. Direct cellular reprogramming is a rapidly evolving and innovative tissue regenerative approach that holds promise to restore functional vasculature and restore blood perfusion. The approach utilises cell plasticity to directly convert somatic cells to another cell fate without a pluripotent stage. In this narrative literature review, we comprehensively analyse and compare direct reprogramming protocols to generate endothelial cells, vascular smooth muscle cells and vascular progenitors. Specifically, we carefully examine the reprogramming factors, their molecular mechanisms, conversion efficacies and therapeutic benefits for each induced vascular cell. Attention is given to the application of these novel approaches with tissue engineered vascular grafts as a therapeutic and disease-modelling platform for cardiovascular diseases. We conclude with a discussion on the ethics of direct reprogramming, its current challenges, and future perspectives.

Comparative study of differentiating human pluripotent stem cells into vascular smooth muscle cells in hydrogel-based culture methods

Vascular smooth muscle cells (VSMCs), which provides structural integrity and regulates the diameter of vasculature, are of great potential for modeling vascular-associated diseases and tissue engineering. Here, we presented a detailed comparison of differentiating human pluripotent stem cells (hPSCs) into VSMCs (hPSCs-VSMCs) in four different culture methods, including 2-dimensional (2D) culture, 3-dimensional (3D) PNIPAAm-PEG hydrogel culture, 3-dimensional (3D) alginate hydrogel culture, and transferring 3-dimensional alginate hydrogel culture to 2-dimensional (2D) culture. Both hydrogel-based culture methods could mimic in vivo microenvironment to protect cells from shear force, and avoid cells agglomeration, resulting in the extremely high culture efficiency (e.g., high viability, high purity and high yield) compared with 2D culture. We demonstrated hPSC-VSMCs produced from hydrogel-based culture methods had better contractile phenotypes and the potential of vasculature formation. The transcriptome analysis showed the hPSC-VSMCs derived from hydrogel-based culture methods displayed more upregulated genes in vasculature development, angiogenesis and blood vessel development, extracellular matrix compared with 2D culture. Taken together, hPSC-VSMCs produced from hydrogel-based culture system could be applied in various biomedical fields, and further indicated the suitable development of alginate hydrogel for industrial production by taking all aspects into consideration.

"Cutting the Mustard" with Induced Pluripotent Stem Cells: An Overview and Applications in Healthcare Paradigm

Treatment of numerous ailments has been made accessible by the advent of genetic engineering, where the self-renewal property has unfolded the mysteries of regeneration, i.e., stem cells. This is narrowed down to pluripotency, the cell property of differentiating into other adult cells. The generation of induced pluripotent stem cells (iPSCs) was a major breakthrough in 2006, which was generated by a cocktail of 4 Yamanaka Factors, following which significant advancements have been reported in medical science and therapeutics. The iPSCs are reprogrammed from somatic cells, and the fascinating results focused on developing authentic techniques for their generation via molecular reprogramming mechanisms, with a plethora of molecules, like NANOG, miRNAs, and DNA modifying agents, etc. The iPSCs have exhibited reliable results in assessing the etiology and molecular mechanisms of diseases, followed by the development of possible treatments and the elimination of risks of immune rejection. The authors formulate a comprehensive review to develop a clear understanding of iPSC generation, their advantages and limitations, with potential challenges associated with their medical utility. In addition, a wide compendium of applications of iPSCs in regenerative medicine and disease modeling has been discussed, alongside bioengineering technologies for iPSC reprogramming, expansion, isolation, and differentiation. The manuscript aims to provide a holistic picture of the booming advancement of iPSC therapy, to attract the attention of global researchers, to investigate this versatile approach in treatment of multiple disorders, subsequently overcoming the challenges, in order to effectively expand its therapeutic window.

Development and Preliminary Testing of Porcine Blood-Derived Endothelial-like Cells for Vascular Tissue Engineering Applications: Protocol Optimisation and Seeding of Decellularised Human Saphenous Veins

Functional endothelial cells (EC) are a critical interface between blood vessels and the thrombogenic flowing blood. Disruption of this layer can lead to early thrombosis, inflammation, vessel restenosis, and, following coronary (CABG) or peripheral (PABG) artery bypass graft surgery, vein graft failure. Blood-derived ECs have shown potential for vascular tissue engineering applications. Here, we show the development and preliminary testing of a method for deriving porcine endothelial-like cells from blood obtained under clinical conditions for use in translational research. The derived cells show cobblestone morphology and expression of EC markers, similar to those seen in isolated porcine aortic ECs (PAEC), and when exposed to increasing shear stress, they remain viable and show mRNA expression of EC markers similar to PAEC. In addition, we confirm the feasibility of seeding endothelial-like cells onto a decellularised human vein scaffold with approximately 90% lumen coverage at lower passages, and show that increasing cell passage results in reduced endothelial coverage.

Mesenchymal Stem/Stromal Cells in Progressive Fibrogenic Involvement and Anti-Fibrosis Therapeutic Properties

Fibrosis refers to the connective tissue deposition and stiffness usually as a result of injury. Fibrosis tissue-resident mesenchymal cells, including fibroblasts, myofibroblast, smooth muscle cells, and mesenchymal stem/stromal cells (MSCs), are major players in fibrogenic processes under certain contexts. Acknowledging differentiation potential of MSCs to the aforementioned other types of mesenchymal cell lineages is essential for better understanding of MSCs’ substantial contributions to progressive fibrogenesis. MSCs may represent a potential therapeutic option for fibrosis resolution owing to their unique pleiotropic functions and therapeutic properties. Currently, clinical trial efforts using MSCs and MSC-based products are underway but clinical data collected by the early phase trials are insufficient to offer better support for the MSC-based anti-fibrotic therapies. Given that MSCs are involved in the coagulation through releasing tissue factor, MSCs can retain procoagulant activity to be associated with fibrogenic disease development. Therefore, MSCs’ functional benefits in translational applications need to be carefully balanced with their potential risks.

Ion channels in stem cells and their roles in stem cell biology and vascular diseases

Stem cell therapy may be a promising option for the treatment of vascular diseases. In recent years, significant progress has been made in stem cell research, especially in the mechanism of stem cell activation, homing and differentiation in vascular repair and reconstruction. Current research on stem cells focuses on protein expression and transcriptional networks. Ion channels are considered to be the basis for the generation of bioelectrical signals, which control the proliferation, differentiation and migration of various cell types. Although heterogeneity of multiple ion channels has been found in different types of stem cells, it is unclear whether the heterogeneous expression of ion channels is related to different cell subpopulations and/or different stages of the cell cycle. There is still a long way to go in clinical treatment by using the regulation of stem cell ion channels. In this review, we reviewed the main ion channels found on stem cells, their expression and function in stem cell proliferation, differentiation and migration, and the research status of stem cells' involvement in vascular diseases.

Human Induced Pluripotent Stem Cell-Derived Vascular Cells: Recent Progress and Future Directions

Human induced pluripotent stem cells (hiPSCs) hold great promise for cardiovascular regeneration following ischemic injury. Considerable effort has been made toward the development and optimization of methods to differentiate hiPSCs into vascular cells, such as endothelial and smooth muscle cells (ECs and SMCs). In particular, hiPSC-derived ECs have shown robust potential for promoting neovascularization in animal models of cardiovascular diseases, potentially achieving significant and sustained therapeutic benefits. However, the use of hiPSC-derived SMCs that possess high therapeutic relevance is a relatively new area of investigation, still in the earlier investigational stages. In this review, we first discuss different methodologies to derive vascular cells from hiPSCs with a particular emphasis on the role of key developmental signals. Furthermore, we propose a standardized framework for assessing and defining the EC and SMC identity that might be suitable for inducing tissue repair and regeneration. We then highlight the regenerative effects of hiPSC-derived vascular cells on animal models of myocardial infarction and hindlimb ischemia. Finally, we address several obstacles that need to be overcome to fully implement the use of hiPSC-derived vascular cells for clinical application.

Endothelial repair by stem and progenitor cells

The integrity of the endothelial barrier is required to maintain vascular homeostasis and fluid balance between the circulatory system and surrounding tissues and to prevent the development of vascular disease. However, the origin of the newly developed endothelial cells is still controversial. Stem and progenitor cells have the potential to differentiate into endothelial cell lines and stimulate vascular regeneration in a paracrine/autocrine fashion. The one source of new endothelial cells was believed to come from the bone marrow, which was challenged by the recent findings. By administration of new techniques, including genetic cell lineage tracing and single cell RNA sequencing, more solid data were obtained that support the concept of stem/progenitor cells for regenerating damaged endothelium. Specifically, it was found that tissue resident endothelial progenitors located in the vessel wall were crucial for endothelial repair. In this review, we summarized the latest advances in stem and progenitor cell research in endothelial regeneration through findings from animal models and discussed clinical data to indicate the future direction of stem cell therapy.

Different Roles of Stem/Progenitor Cells in Vascular Remodeling

Significance: Since the discovery of vascular stem cells, there has been considerable advancement in comprehending the nature and functions of these cells. Due to their differentiation potential to repair endothelial cells and to participate in lesion formation during vascular remodeling, it is crucial to elucidate vascular stem cell behaviors and the mechanisms underlying this process, which could provide new chances for the design of clinical therapeutic application of stem cells. Recent Advances: Over the past decades, major progress has been made on progenitor/vascular stem cells in the field of cardiovascular research. Vascular stem cells are mostly latent in their niches and can be bioactivated in response to damage and get involved in endothelial repair and smooth muscle cell aggregation to generate neointima. Accumulating evidence has been shown recently, using genetic lineage tracing mouse models, to particularly provide solutions to the nature of vascular stem cells and to monitor both cell migration and the process of differentiation during physiological angiogenesis and in vascular diseases. Critical Issues: This article reviews and summarizes the current research progress of vascular stem cells in this field and highlights future prospects for stem cell research in regenerative medicine. Future Directions: Despite recent advances and achievements of stem cells in cardiovascular research, the nature and cell fate of vascular stem cells remain elusive. Further comprehensive studies using new techniques including genetic cell lineage tracing and single-cell RNA sequencing are essential to fully illuminate the role of stem cells in vascular development and diseases. Antioxid. Redox Signal. 35, 192-203.

Biofabrication of tissue engineering vascular systems

Cardiovascular disease (CVD) is the leading cause of death among persons aged 65 and older in the United States and many other developed countries. Tissue engineered vascular systems (TEVS) can serve as grafts for CVD treatment and be used as in vitro model systems to examine the role of various genetic factors during the CVD progressions. Current focus in the field is to fabricate TEVS that more closely resembles the mechanical properties and extracellular matrix environment of native vessels, which depends heavily on the advance in biofabrication techniques and discovery of novel biomaterials. In this review, we outline the mechanical and biological design requirements of TEVS and explore the history and recent advances in biofabrication methods and biomaterials for tissue engineered blood vessels and microvascular systems with special focus on in vitro applications. In vitro applications of TEVS for disease modeling are discussed.

Perivascular tissue stem cells are crucial players in vascular disease

Perivascular tissue including adipose layer and adventitia have been considered to play pivotal roles in vascular development and disease progression. Recent studies showed that abundant stem/progenitorcells (SPCs) are present in perivascular tissues. These SPCs exhibit capability to proliferate and differentiate into specific terminal cells. Adult perivascular SPCs are quiescent in normal condition, once activated by specific molecules (e.g., cytokines), they migrate toward the lumen side where they differentiate into both smooth muscle cells (SMCs) and endothelial cells (ECs), thus promoting intima hyperplasia or endothelial regeneration. In addition, perivascular SPCs can also regulate vascular diseases via other ways including but not limited to paracrine effects, matrix protein modulation and microvessel formation. Perivascular SPCs have also been shown to possess therapeutic potentials due to the capability to differentiate into vascular cells and regenerate vascular structures. This review summarizes current knowledge on resident SPCs features and discusses the potential benefits of SPCs therapy in vascular diseases.

Cellular remodeling of fibrotic conduit as vascular graft

The replacement of small-diameter arteries remains an unmet clinical need. Here we investigated the cellular remodeling of fibrotic conduits as vascular grafts. The formation of fibrotic conduit around subcutaneously implanted mandrels involved not only fibroblasts but also the trans-differentiation of inflammatory cells such as macrophages into fibroblastic cells, as shown by genetic lineage tracing. When fibrotic conduits were implanted as vascular grafts, the patency was low, and many fibrotic cells were found in neointima. Decellularization and anti-thrombogenic coating of fibrotic conduits produced highly patent autografts that remodeled into neoarteries, offering an effective approach to obtain autografts for clinical therapy. While autografts recruited mostly anti-inflammatory macrophages for constructive remodeling, allogenic DFCs had more T cells and pro-inflammatory macrophages and lower patency. Endothelial progenitors and endothelial migration were observed during endothelialization. Cell infiltration into DFCs was more efficient than decellularized arteries, and infiltrated cells remodeled the matrix and differentiated into smooth muscle cells (SMCs). This work provides insight into the remodeling of fibrotic conduits, autologous DFCs and allogenic DFCs, and will have broad impact on using fibrotic matrix for regenerative engineering.

Mapping regulators of cell fate determination: Approaches and challenges

Given the limited regenerative capacities of most organs, strategies are needed to efficiently generate large numbers of parenchymal cells capable of integration into the diseased organ. Although it was initially thought that terminally differentiated cells lacked the ability to transdifferentiate, it has since been shown that cellular reprogramming of stromal cells to parenchymal cells through direct lineage conversion holds great potential for the replacement of post-mitotic parenchymal cells lost to disease. To this end, an assortment of genetic, chemical, and mechanical cues have been identified to reprogram cells to different lineages both in vitro and in vivo. However, some key challenges persist that limit broader applications of reprogramming technologies. These include: (1) low reprogramming efficiencies; (2) incomplete functional maturation of derived cells; and (3) difficulty in determining the typically multi-factor combinatorial recipes required for successful transdifferentiation. To improve efficiency by comprehensively identifying factors that regulate cell fate, large scale genetic and chemical screening methods have thus been utilized. Here, we provide an overview of the underlying concept of cell reprogramming as well as the rationale, considerations, and limitations of high throughput screening methods. We next follow with a summary of unique hits that have been identified by high throughput screens to induce reprogramming to various parenchymal lineages. Finally, we discuss future directions of applying this technology toward human disease biology via disease modeling, drug screening, and regenerative medicine.

An in situ collagen-HA hydrogel system promotes survival and preserves the proangiogenic secretion of hiPSC-derived vascular smooth muscle cells

Human-induced pluripotent stem cell-derived vascular smooth muscle cells (hiPSC-VSMCs) with proangiogenic properties have huge therapeutic potential. While hiPSC-VSMCs have already been utilized for wound healing using a biomimetic collagen scaffold, an in situ forming hydrogel mimicking the native environment of skin offers the promise of hiPSC-VSMC mediated repair and regeneration. Herein, the impact of a collagen type-I-hyaluronic acid (HA) in situ hydrogel cross-linked using a polyethylene glycol-based cross-linker on hiPSC-VSMCs viability and proangiogenic paracrine secretion was investigated. Our study demonstrated increases in cell viability, maintenance of phenotype and proangiogenic growth factor secretion, and proangiogenic activity in response to the conditioned medium. The optimally cross-linked and functionalized collagen type-I/HA hydrogel system developed in this study shows promise as an in situ hiPSC-VSMC carrier system for wound regeneration.

Identification of key genes in ruptured atherosclerotic plaques by weighted gene correlation network analysis

The rupture of atherosclerotic plaques is essential for cardiovascular and cerebrovascular events. Identification of the key genes related to plaque rupture is an important approach to predict the status of plaque and to prevent the clinical events. In the present study, we downloaded two expression profiles related to the rupture of atherosclerotic plaques (GSE41571 and GSE120521) from GEO database. 11 samples in GSE41571 were used to identify the differentially expressed genes (DEGs) and to construct the weighted gene correlation network analysis (WGCNA) by R software. The gene oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment tool in DAVID website, and the Protein-protein interactions in STRING website were used to predict the functions and mechanisms of genes. Furthermore, we mapped the hub genes extracted from WGCNA to DEGs, and constructed a sub-network using Cytoscape 3.7.2. The key genes were identified by the molecular complex detection (MCODE) in Cytoscape. Further validation was conducted using dataset GSE120521 and human carotid endarterectomy (CEA) plaques. Results: In our study, 868 DEGs were identified in GSE41571. Six modules with 236 hub genes were identified through WGCNA analysis. Among these six modules, blue and brown modules were of the highest correlations with ruptured plaques (with a correlation of 0.82 and −0.9 respectively). 72 hub genes were identified from blue and brown modules. These 72 genes were the most likely ones being related to cell adhesion, extracellular matrix organization, cell growth, cell migration, leukocyte migration, PI₃K-Akt signaling, focal adhesion, and ECM-receptor interaction. Among the 72 hub genes, 45 were mapped to the DEGs (logFC > 1.0, p-value < 0.05). The sub-network of these 45 hub genes and MCODE analysis indicated 3 clusters (13 genes) as key genes. They were LOXL1, FBLN5, FMOD, ELN, EFEMP1 in cluster 1, RILP, HLA-DRA, HLA-DMB, HLA-DMA in cluster 2, and SFRP4, FZD6, DKK3 in cluster 3. Further expression detection indicated EFEMP1, BGN, ELN, FMOD, DKK3, FBLN5, FZD6, HLA-DRA, HLA-DMB, HLA-DMA, and RILP might have potential diagnostic value.

Efficient differentiation of vascular smooth muscle cells from Wharton's Jelly mesenchymal stromal cells using human platelet lysate: A potential cell source for small blood vessel engineering

BACKGROUND

The development of fully functional small diameter vascular grafts requires both a properly defined vessel conduit and tissue-specific cellular populations. Mesenchymal stromal cells (MSCs) derived from the Wharton's Jelly (WJ) tissue can be used as a source for obtaining vascular smooth muscle cells (VSMCs), while the human umbilical arteries (hUAs) can serve as a scaffold for blood vessel engineering.

AIM

To develop VSMCs from WJ-MSCs utilizing umbilical cord blood platelet lysate.

METHODS

WJ-MSCs were isolated and expanded until passage (P) 4. WJ-MSCs were properly defined according to the criteria of the International Society for Cell and Gene Therapy. Then, these cells were differentiated into VSMCs with the use of platelet lysate from umbilical cord blood in combination with ascorbic acid, followed by evaluation at the gene and protein levels. Specifically, gene expression profile analysis of VSMCs for ACTA2, MYH11, TGLN, MYOCD, SOX9, NANOG homeobox, OCT4 and GAPDH, was performed. In addition, immunofluorescence against ACTA2 and MYH11 in combination with DAPI staining was also performed in VSMCs. HUAs were decellularized and served as scaffolds for possible repopulation by VSMCs. Histological and biochemical analyses were performed in repopulated hUAs.

RESULTS

WJ-MSCs exhibited fibroblastic morphology, successfully differentiating into "osteocytes", "adipocytes" and "chondrocytes", and were characterized by positive expression (> 90%) of CD90, CD73 and CD105. In addition, WJ-MSCs were successfully differentiated into VSMCs with the proposed differentiation protocol. VSMCs successfully expressed ACTA2, MYH11, MYOCD, TGLN and SOX9. Immunofluorescence results indicated the expression of ACTA2 and MYH11 in VSMCs. In order to determine the functionality of VSMCs, hUAs were isolated and decellularized. Based on histological analysis, decellularized hUAs were free of any cellular or nuclear materials, while their extracellular matrix retained intact. Then, repopulation of decellularized hUAs with VSMCs was performed for 3 wk. Decellularized hUAs were repopulated efficiently by the VSMCs. Biochemical analysis revealed the increase of total hydroyproline and sGAG contents in repopulated hUAs with VSMCs. Specifically, total hydroxyproline and sGAG content after the 1st, 2nd and 3rd wk was 71 ± 10, 74 ± 9 and 86 ± 8 μg hydroxyproline/mg of dry tissue weight and 2 ± 1, 3 ± 1 and 3 ± 1 μg sGAG/mg of dry tissue weight, respectively. Statistically significant differences were observed between all study groups (P < 0.05).

CONCLUSION

VSMCs were successfully obtained from WJ-MSCs with the proposed differentiation protocol. Furthermore, hUAs were efficiently repopulated by VSMCs. Differentiated VSMCs from WJ-MSCs could provide an alternative source of cells for vascular tissue engineering.

Intracavernous delivery of Dickkopf3 gene or peptide rescues erectile function through enhanced cavernous angiogenesis in the diabetic mouse

BACKGROUND

Severe peripheral angiopathy in patients with diabetes is a major contributing factor for low response rate to phosphodiesterase-5 inhibitors.

OBJECTIVES

To examine whether and how Dickkopf3 (DKK3), a secreted modulator of the Wnt pathway that known to be involved in endothelial cell repair and vascular progenitor cell migration, restores erectile function in diabetic mice.

METHODS

Eight-week-old C57BL/6 mice received intraperitoneal injections of streptozotocin (50 mg/kg for 5 days). Eight weeks after the diabetes was induced, the efficacy of DKK3 was determined by three independent experiments: experiment 1 (DKK3 peptide [5 μg in 20 μL PBS]); experiment 2 (DKK3 plasmid DNA with electroporation [10, 40, or 100 μg in 20 μL PBS, respectively]); and experiment 3 (DKK3 adenovirus [1 × 10⁷ , 1 × 10⁸ , 1 × 10⁹ virus particles per 20 μL, respectively]). Erectile function was measured by electrical stimulation of the cavernous nerve one week (for peptide) or two weeks (for genes) after treatment. The angiogenic activity of DKK3 was determined in diabetic penis in vivo and in primary cultured mouse cavernous endothelial cells (MCECs) in vitro.

RESULTS

The cavernous expression of DKK3 protein was significantly lower in the diabetic mice than in controls. DKK3 peptide or adenovirus significantly improved erectile function in diabetic mice (70% of the control values). DKK3 adenovirus profoundly restored cavernous endothelial cell and pericyte contents and increased endothelial junction proteins in diabetic mice in vivo. DKK3 peptide induced upregulation of angiogenic factors (angiopoietin-1, vascular endothelial growth factor, and basic fibroblast growth factor) and accelerated tube formation in MCECs cultivated under the high-glucose condition in vitro.

CONCLUSION

DKK3 restored cavernous vascular integrity and improved erectile function in diabetic mice. Therapeutic cavernous angiogenesis by the use of DKK3 will be a promising therapeutic strategy to treat diabetic erectile dysfunction.

Vascular Microphysiological Systems to Model Diseases

Human vascular microphysiological systems (MPS) represent promising three-dimensional in vitro models of normal and diseased vascular tissue. These systems build upon advances in tissue engineering, microfluidics, and stem cell differentiation and replicate key functional units of organs and tissues. Vascular models have been developed for the microvasculature as well as medium-size arterioles. Key functions of the vascular system have been reproduced and stem cells offer the potential to model genetic diseases and population variation in genes that may increase individual risk for cardiovascular disease. Such systems can be used to evaluate new therapeutics options.

DKK3 (Dikkopf-3) Transdifferentiates Fibroblasts Into Functional Endothelial Cells-Brief Report

Objective- To determine the role of a cytokine-like protein DKK3 (dikkopf-3) in directly transdifferentiating fibroblasts into endothelial cells (ECs) and the underlying mechanisms. Approach and Results- DKK3 overexpression in human fibroblasts under defined conditions for 4 days led to a notable change in cell morphology and progenitor gene expression. It was revealed that these cells went through mesenchymal-to-epithelial transition and subsequently expressed KDR (kinase insert domain receptor) at high levels. Further culture in EC defined media led to differentiation of these progenitors into functional ECs capable of angiogenesis both in vitro and in vivo, which was regulated by the VEGF (vascular endothelial growth factor)/miR (microRNA)-125a-5p/Stat3 (signal transducer and activator of transcription factor 3) axis. More importantly, fibroblast-derived ECs showed the ability to form a patent endothelium-like monolayer in tissue-engineered vascular grafts ex vivo. Conclusions- These data demonstrate that DKK3 is capable of directly differentiating human fibroblasts to functional ECs under defined media and provides a novel potential strategy for endothelial regeneration.

Dickkopf-3 in aberrant endothelial secretome triggers renal fibroblast activation and endothelial-mesenchymal transition

Background

Our laboratory has previously demonstrated that Sirt1endo-/- mice show endothelial dysfunction and exaggerated renal fibrosis, whereas mice with silenced endothelial transforming growth factor beta (TGF-β) signaling are resistant to fibrogenic signals. Considering the fact that the only difference between these mutant mice is confined to the vascular endothelium, this indicates that secreted substances contribute to these contrasting responses.

Methods

We performed an unbiased proteomic analysis of the secretome of renal microvascular endothelial cells (RMVECs) isolated from these two mutants. We cultured renal fibroblasts and RMVECs and used microfluidic devices for coculturing.

Results

Dickkopf-3 (DKK3), a putative ligand of the Wnt/β-catenin pathway, was present exclusively in the fibrogenic secretome. In cultured fibroblasts, DKK3 potently induced myofibroblast activation. In addition, DKK3 antagonized effects of DKK1, a known inhibitor of the Wnt pathway, in conversion of fibroblasts to myofibroblasts. In RMVECs, DKK3 induced endothelial-mesenchymal transition and impaired their angiogenic competence. The inhibition of endothelial outgrowth, enhanced myofibroblast formation and endothelial-mesenchymal transition were confirmed in coculture. In reporter DKK3-eGFP × Col3.6-GFPcyan mice, DKK3 was marginally expressed under basal conditions. Adriamycin-induced nephropathy resulted in upregulation of DKK3 expression in tubular and, to a lesser degree, endothelial compartments. Sulindac sulfide was found to exhibit superior Wnt pathway-suppressive action and decreased DKK3 signals and the extent of renal fibrosis.

Conclusions

In conclusion, this unbiased proteomic screen of the profibrogenic endothelial secretome revealed DKK3 acting as an agonist of the Wnt pathway, enhancing formation of myofibroblasts and endothelial-mesenchymal transition and impairing angiogenesis. A potent inhibitor of the Wnt pathway, sulindac sulfide, suppressed nephropathy-induced DKK3 expression and renal fibrosis.

Oct4-mediated reprogramming induces embryonic-like microRNA expression signatures in human fibroblasts

Oct4-mediated reprogramming has recently become a novel tool for the generation of various cell types from differentiated somatic cells. Although molecular mechanisms underlying this process are unknown, it is well documented that cells over-expressing Oct4 undergo transition from differentiated state into plastic state. This transition is associated with the acquisition of stem cells properties leading to epigenetically “open” state that is permissive to cell fate switch upon external stimuli. In order to contribute to our understanding of molecular mechanisms driving this process, we characterised human fibroblasts over-expressing Oct4 and performed comprehensive small-RNAseq analysis. Our analyses revealed new interesting aspects of Oct4-mediated cell plasticity induction. Cells over-expressing Oct4 lose their cell identity demonstrated by down-regulation of fibroblast-specific genes and up-regulation of epithelial genes. Interestingly, this process is associated with microRNA expression profile that is similar to microRNA profiles typically found in pluripotent stem cells. We also provide extensive network of microRNA families and clusters allowing us to precisely determine the miRNAome associated with the acquisition of Oct4-induced transient plastic state. Our data expands current knowledge of microRNA and their implications in cell fate alterations and contributing to understanding molecular mechanisms underlying it.

Binding of Dickkopf-3 to CXCR7 Enhances Vascular Progenitor Cell Migration and Degradable Graft Regeneration

Supplemental Digital Content is available in the text.

Rationale:

Vascular progenitor cells play key roles in physiological and pathological vascular remodeling—a process that is crucial for the regeneration of acellular biodegradable scaffolds engineered as vital strategies against the limited availability of healthy autologous vessels for bypass grafting. Therefore, understanding the mechanisms driving vascular progenitor cells recruitment and differentiation could help the development of new strategies to improve tissue-engineered vessel grafts and design drug-targeted therapy for vessel regeneration.

Objective:

In this study, we sought to investigate the role of Dkk3 (dickkopf-3), recently identified as a cytokine promotor of endothelial repair and smooth muscle cell differentiation, on vascular progenitor cells cell migration and vascular regeneration and to identify its functional receptor that remains unknown.

Methods and Results:

Vascular stem/progenitor cells were isolated from murine aortic adventitia and selected for the Sca-1 (stem cell antigen-1) marker. Dkk3 induced the chemotaxis of Sca-1+ cells in vitro in transwell and wound healing assays and ex vivo in the aortic ring assay. Functional studies to identify Dkk3 receptor revealed that overexpression or knockdown of chemokine receptor CXCR7 (C-X-C chemokine receptor type 7) in Sca-1+ cells resulted in alterations in cell migration. Coimmunoprecipitation experiments using Sca-1+ cell extracts treated with Dkk3 showed the physical interaction between DKK3 and CXCR7, and specific saturation binding assays identified a high-affinity Dkk3-CXCR7 binding with a dissociation constant of 14.14 nmol/L. Binding of CXCR7 by Dkk3 triggered the subsequent activation of ERK1/2 (extracellular signal-regulated kinases 1/2)-, PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B)-, Rac1 (Ras-related C3 botulinum toxin substrate 1)-, and RhoA (Ras homolog gene family, member A)-signaling pathways involved in Sca-1+ cell migration. Tissue-engineered vessel grafts were fabricated with or without Dkk3 and implanted to replace the rat abdominal aorta. Dkk3-loaded tissue-engineered vessel grafts showed efficient endothelization and recruitment of vascular progenitor cells, which had acquired characteristics of mature smooth muscle cells. CXCR7 blocking using specific antibodies in this vessel graft model hampered stem/progenitor cell recruitment into the vessel wall, thus compromising vascular remodeling.

Conclusions:

We provide a novel and solid evidence that CXCR7 serves as Dkk3 receptor, which mediates Dkk3-induced vascular progenitor migration in vitro and in tissue-engineered vessels, hence harnessing patent grafts resembling native blood vessels.

Adventitial Cell Atlas of wt (Wild Type) and ApoE (Apolipoprotein E)-Deficient Mice Defined by Single-Cell RNA Sequencing

Objective- Vascular adventitia encompasses progenitors and is getting recognized as the major site of inflammation in early stage of atherosclerosis. However, the cellular atlas of the heterogeneous adventitial cells, the intercellular communication, the cellular response of adventitia to hyperlipidemia, and its contribution to atherosclerosis have been elusive. Approach and Results- Single-cell RNA sequencing was applied to wt (wild type) and ApoE (apolipoprotein E)-deficient aortic adventitia from 12-week-old C57BL/6J mice fed on normal laboratory diet with early stage of atherosclerosis. Unbiased clustering analysis revealed that the landscape of adventitial cells encompassed adventitial mesenchyme cells, immune cells (macrophages, T cells, and B cells), and some types of rare cells, for example, neuron, lymphatic endothelial cells, and innate lymphoid cells. Seurat clustering analysis singled out 6 nonimmune clusters with distinct transcriptomic profiles, in which there predominantly were stem/progenitor cell-like and proinflammatory population (Mesen II). In ApoE-deficient adventitia, resident macrophages were activated and related to increased myeloid cell infiltration in the adventitia. Cell communication analysis further elucidated enhanced interaction between a mesenchyme cluster and inflammatory macrophages in ApoE-deficient adventitia. In vitro transwell assay confirmed the proinflammatory role of SCA1+ (stem cell antigen 1 positive) Mesen II population with increased CCL2 (chemokine [C-C motif] ligand 2) secretion and thus increased capacity to attract immune cells in ApoE-deficient adventitia. Conclusions- Cell atlas defined by single-cell RNA sequencing depicted the heterogeneous cellular landscape of the adventitia and uncovered several types of cell populations. Furthermore, resident cell interaction with immune cells appears crucial at the early stage of atherosclerosis.

A Human Pluripotent Stem Cell-Based Screen for Smooth Muscle Cell Differentiation and Maturation Identifies Inhibitors of Intimal Hyperplasia

Contractile to synthetic phenotypic switching of smooth muscle cells (SMCs) contributes to stenosis in vascular disease and vascular transplants. To generate more contractile SMCs, we performed a high-throughput differentiation screen using a MYH11-NLuc-tdTomato human embryonic stem cell reporter cell line. We identified RepSox as a factor that promotes differentiation of MYH11-positive cells by promoting NOTCH signaling. RepSox induces SMCs to exhibit a more contractile phenotype than SMCs generated using PDGF-BB and TGF-β1, two factors previously used for SMC differentiation but which also cause intimal hyperplasia. In addition, RepSox inhibited intimal hyperplasia caused by contractile to synthetic phenotypic switching of SMCs in a rat balloon injury model. Thus, in addition to providing more contractile SMCs that could prove useful for constructing artificial blood vessels, this study suggests a strategy for identifying drugs for inhibiting intimal hyperplasia that act by driving contractile differentiation rather than inhibiting proliferation non-specifically.

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Fully defined differentiation of contractile (95% MYH11⁺) smooth muscle cells (SMCs)

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RepSox-NOTCH signal promotes SMC differentiation and inhibits intimal hyperplasia

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RepSox-SMCs could reduce the risk of intimal hyperplasia compared with PDGF/TGF-SMCs

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Applying SMC differentiation for high-throughput screening of anti-restenosis drugs

Engineered Microenvironment for Manufacturing Human Pluripotent Stem Cell-Derived Vascular Smooth Muscle Cells

Human pluripotent stem cell-derived vascular smooth muscle cells (hPSC-VSMCs) are of great value for disease modeling, drug screening, cell therapies, and tissue engineering. However, producing a high quantity of hPSC-VSMCs with current cell culture technologies remains very challenging. Here, we report a scalable method for manufacturing hPSC-VSMCs in alginate hydrogel microtubes (i.e., AlgTubes), which protect cells from hydrodynamic stresses and limit cell mass to <400 μm to ensure efficient mass transport. The tubes provide cells a friendly microenvironment, leading to extremely high culture efficiency. We have shown that hPSC-VSMCs can be generated in 10 days with high viability, high purity, and high yield (∼5.0 × 108 cells/mL). Phenotype and gene expression showed that VSMCs made in AlgTubes and VSMCs made in 2D cultures were similar overall. However, AlgTube-VSMCs had higher expression of genes related to vasculature development and angiogenesis, and 2D-VSMCs had higher expression of genes related to cell death and biosynthetic processes.

Regenerating the Cardiovascular System Through Cell Reprogramming; Current Approaches and a Look Into the Future

Cardiovascular disease (CVD), despite the advances of the medical field, remains one of the leading causes of mortality worldwide. Discovering novel treatments based on cell therapy or drugs is critical, and induced pluripotent stem cells (iPS Cells) technology has made it possible to design extensive disease-specific in vitro models. Elucidating the differentiation process challenged our previous knowledge of cell plasticity and capabilities and allows the concept of cell reprogramming technology to be established, which has inspired the creation of both in vitro and in vivo techniques. Patient-specific cell lines provide the opportunity of studying their pathophysiology in vitro, which can lead to novel drug development. At the same time, in vivo models have been designed where in situ transdifferentiation of cell populations into cardiomyocytes or endothelial cells (ECs) give hope toward effective cell therapies. Unfortunately, the efficiency as well as the concerns about the safety of all these methods make it exceedingly difficult to pass to the clinical trial phase. It is our opinion that creating an ex vivo model out of patient-specific cells will be one of the most important goals in the future to help surpass all these hindrances. Thus, in this review we aim to present the current state of research in reprogramming toward the cardiovascular system's regeneration, and showcase how the development and study of a multicellular 3D ex vivo model will improve our fighting chances.

AAVvector-mediated in vivo reprogramming into pluripotency

In vivo reprogramming of somatic cells into induced pluripotent stem cells (iPSC) holds vast potential for basic research and regenerative medicine. However, it remains hampered by a need for vectors to express reprogramming factors (Oct-3/4, Klf4, Sox2, c-Myc; OKSM) in selected organs. Here, we report OKSM delivery vectors based on pseudotyped Adeno-associated virus (AAV). Using the AAV-DJ capsid, we could robustly reprogram mouse embryonic fibroblasts with low vector doses. Swapping to AAV8 permitted to efficiently reprogram somatic cells in adult mice by intravenous vector delivery, evidenced by hepatic or extra-hepatic teratomas and iPSC in the blood. Notably, we accomplished full in vivo reprogramming without c-Myc. Most iPSC generated in vitro or in vivo showed transcriptionally silent, intronic or intergenic vector integration, likely reflecting the increased host genome accessibility during reprogramming. Our approach crucially advances in vivo reprogramming technology, and concurrently facilitates investigations into the mechanisms and consequences of AAV persistence.

In vivo reprogramming of somatic cells is hampered by the need for vectors to express the OKSM factors in selected organs. Here the authors report new AAV-based vectors capable of in vivo reprogramming at low doses.

Human induced pluripotent stem cell-derived vascular smooth muscle cells: differentiation and therapeutic potential

Cardiovascular diseases remain the leading cause of death worldwide and current treatment strategies have limited effect of disease progression. It would be desirable to have better models to study developmental and pathological processes and model vascular diseases in laboratory settings. To this end, human induced pluripotent stem cells (hiPSCs) have generated great enthusiasm, and have been a driving force for development of novel strategies in drug discovery and regenerative cell-therapy for the last decade. Hence, investigating the mechanisms underlying the differentiation of hiPSCs into specialized cell types such as cardiomyocytes, endothelial cells, and vascular smooth muscle cells (VSMCs) may lead to a better understanding of developmental cardiovascular processes and potentiate progress of safe autologous regenerative therapies in pathological conditions. In this review, we summarize the latest trends on differentiation protocols of hiPSC-derived VSMCs and their potential application in vascular research and regenerative therapy.

Role of Resident Stem Cells in Vessel Formation and Arteriosclerosis

Vascular, resident stem cells are present in all 3 layers of the vessel wall; they play a role in vascular formation under physiological conditions and in remodeling in pathological situations. Throughout development and adult early life, resident stem cells participate in vessel formation through vasculogenesis and angiogenesis. In adults, the vascular stem cells are mostly quiescent in their niches but can be activated in response to injury and participate in endothelial repair and smooth muscle cell accumulation to form neointima. However, delineation of the characteristics and of the migration and differentiation behaviors of these stem cells is an area of ongoing investigation. A set of genetic mouse models for cell lineage tracing has been developed to specifically address the nature of these cells and both migration and differentiation processes during physiological angiogenesis and in vascular diseases. This review summarizes the current knowledge on resident stem cells, which has become more defined and refined in vascular biology research, thus contributing to the development of new potential therapeutic strategies to promote endothelial regeneration and ameliorate vascular disease development.

Smooth muscle cells differentiated from mesenchymal stem cells are regulated by microRNAs and suitable for vascular tissue grafts

Tissue-engineered vascular grafts with long-term patency are greatly needed in the clinical settings, and smooth muscle cells (SMCs) are a critical graft component. Human mesenchymal stem cells (MSCs) are used for generating SMCs, and understanding the underlying regulatory mechanisms of the MSC-to-SMC differentiation process could improve SMC generation in the clinic. Here, we found that in response to stimulation of transforming growth factor-β1 (TGFβ1), human umbilical cord-derived MSCs abundantly express the SMC markers α-smooth muscle actin (αSMA), smooth muscle protein 22 (SM22), calponin, and smooth muscle myosin heavy chain (SMMHC) at both gene and protein levels. Functionally, MSC-derived SMCs displayed contracting capacity in vitro and supported vascular structure formation in the Matrigel plug assay in vivo More importantly, SMCs differentiated from human MSCs could migrate into decellularized mouse aorta and give rise to the smooth muscle layer of vascular grafts, indicating the potential of utilizing human MSC-derived SMCs to generate vascular grafts. Of note, microRNA (miR) array analysis and TaqMan microRNA assays identified miR-503 and miR-222-5p as potential regulators of MSC differentiation into SMCs at early time points. Mechanistically, miR-503 promoted SMC differentiation by directly targeting SMAD7, a suppressor of SMAD-related, TGFβ1-mediated signaling pathways. Moreover, miR-503 expression was SMAD4-dependent. SMAD4 was enriched at the miR-503 promoter. Furthermore, miR-222-5p inhibited SMC differentiation by targeting and down-regulating ROCK2 and αSMA. In conclusion, MSC differentiation into SMCs is regulated by miR-503 and miR-222-5p and yields functional SMCs for use in vascular grafts.

Mesenchymal stem cells and vascular regeneration

In recent years, MSCs have emerged as a promising therapeutic cell type in regenerative medicine. They hold great promise for treating cardiovascular diseases, such as myocardial infarction and limb ischemia. MSCs may be utilized in both cell-based therapy and vascular graft engineering to restore vascular function, thereby providing therapeutic benefits to patients. The efficacy of MSCs lies in their multipotent differentiation ability toward vascular smooth muscle cells, endothelial cells and other cell types, as well as their capacity to secrete various trophic factors, which are potent in promoting angiogenesis, inhibiting apoptosis and modulating immunoreaction. Increasing our understanding of the mechanisms of MSC involvement in vascular regeneration will be beneficial in boosting present therapeutic approaches and developing novel ones to treat cardiovascular diseases. In this review, we aim to summarize current progress in characterizing the in vivo identity of MSCs, to discuss mechanisms involved in cell-based therapy utilizing MSCs, and to explore current and future strategies for vascular regeneration.

DKK3 (Dickkopf 3) Alters Atherosclerotic Plaque Phenotype Involving Vascular Progenitor and Fibroblast Differentiation Into Smooth Muscle Cells

OBJECTIVE

DKK3 (dickkopf 3), a 36-kD secreted glycoprotein, has been shown to be involved in the differentiation of partially reprogrammed cells and embryonic stem cells to smooth muscle cells (SMCs), but little is known about its involvement in vascular disease. This study aims to assess the effects of DKK3 on atherosclerotic plaque composition.

APPROACH AND RESULTS

In the present study, we used a murine model of atherosclerosis (ApoE^-/-) in conjunction with DKK3^-/- and performed tandem stenosis of the carotid artery to evaluate atherosclerotic plaque development. We found that the absence of DKK3 leads to vulnerable atherosclerotic plaques, because of a reduced number of SMCs and reduced matrix protein deposition, as well as increased hemorrhage and macrophage infiltration. Further in vitro studies revealed that DKK3 can induce differentiation of Sca1⁺ (stem cells antigen 1) vascular progenitors and fibroblasts into SMCs via activation of the TGF-β (transforming growth factor-β)/ATF6 (activating transcription factor 6) and Wnt signaling pathways. Finally, we assessed the therapeutic potential of DKK3 in mouse and rabbit models and found that DKK3 altered the atherosclerotic plaque content via increasing SMC numbers and reducing vascular inflammation.

CONCLUSIONS

Cumulatively, we provide the first evidence that DKK3 is a potent SMC differentiation factor, which might have a therapeutic effect in reducing intraplaque hemorrhage related to atherosclerotic plaque phenotype.

Tissue-Engineered Vascular Rings from Human iPSC-Derived Smooth Muscle Cells

There is an urgent need for an efficient approach to obtain a large-scale and renewable source of functional human vascular smooth muscle cells (VSMCs) to establish robust, patient-specific tissue model systems for studying the pathogenesis of vascular disease, and for developing novel therapeutic interventions. Here, we have derived a large quantity of highly enriched functional VSMCs from human induced pluripotent stem cells (hiPSC-VSMCs). Furthermore, we have engineered 3D tissue rings from hiPSC-VSMCs using a facile one-step cellular self-assembly approach. The tissue rings are mechanically robust and can be used for vascular tissue engineering and disease modeling of supravalvular aortic stenosis syndrome. Our method may serve as a model system, extendable to study other vascular proliferative diseases for drug screening. Thus, this report describes an exciting platform technology with broad utility for manufacturing cell-based tissues and materials for various biomedical applications.

Differentiation and Application of Induced Pluripotent Stem Cell–Derived Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) play a role in the development of vascular disease, for example, neointimal formation, arterial aneurysm, and Marfan syndrome caused by genetic mutations in VSMCs, but little is known about the mechanisms of the disease process. Advances in induced pluripotent stem cell technology have now made it possible to derive VSMCs from several different somatic cells using a selection of protocols. As such, researchers have set out to delineate key signaling processes involved in triggering VSMC gene expression to grasp the extent of gene regulatory networks involved in phenotype commitment. This technology has also paved the way for investigations into diseases affecting VSMC behavior and function, which may be treatable once an identifiable culprit molecule or gene has been repaired. Moreover, induced pluripotent stem cell–derived VSMCs are also being considered for their use in tissue-engineered blood vessels as they may prove more beneficial than using autologous vessels. Finally, while several issues remains to be clarified before induced pluripotent stem cell–derived VSMCs can become used in regenerative medicine, they do offer both clinicians and researchers hope for both treating and understanding vascular disease. In this review, we aim to update the recent progress on VSMC generation from stem cells and the underlying molecular mechanisms of VSMC differentiation. We will also explore how the use of induced pluripotent stem cell–derived VSMCs has changed the game for regenerative medicine by offering new therapeutic avenues to clinicians, as well as providing researchers with a new platform for modeling of vascular disease.

Transdifferentiated Human Vascular Smooth Muscle Cells are a New Potential Cell Source for Endothelial Regeneration

Endothelial dysfunction is widely implicated in cardiovascular pathological changes and development of vascular disease. In view of the fact that the spontaneous endothelial cell (EC) regeneration is a slow and insufficient process, it is of great interest to explore alternative cell sources capable of generating functional ECs. Vascular smooth muscle cell (SMC) composes the majority of the vascular wall and retains phenotypic plasticity in response to various stimuli. The aim of this study is to test the feasibility of the conversion of SMC into functional EC through the use of reprogramming factors. Human SMCs are first dedifferentiated for 4 days to achieve a vascular progenitor state expressing CD34, by introducing transcription factors OCT4, SOX2, KLF4 and c-MYC. These SMC-derived progenitors are then differentiated along the endothelial lineage. The SMC-converted ECs exhibit typical endothelial markers expression and endothelial functions in vitro, in vivo and in disease model. Further comprehensive analysis indicates that mesenchymal-to-epithelial transition is requisite to initiate SMCs reprogramming into vascular progenitors and that members of the Notch signalling pathway regulate further differentiation of the progenitors into endothelial lineage. Together, we provide the first evidence of the feasibility of the conversion of human SMCs towards endothelial lineage through an intermediate vascular progenitor state induced by reprogramming.

A Cytokine-Like Protein Dickkopf-Related Protein 3 Is Atheroprotective

Supplemental Digital Content is available in the text.

Background:

Dickkopf-related protein 3 (DKK3) is a secreted protein that is involved in the regulation of cardiac remodeling and vascular smooth muscle cell differentiation, but little is known about its role in atherosclerosis.

Methods:

We tested the hypothesis that DKK3 is atheroprotective using both epidemiological and experimental approaches. Blood DKK3 levels were measured in the Bruneck Study in 2000 (n=684) and then in 2005 (n=574). DKK3-deficient mice were crossed with apolipoprotein E^-/- mice to evaluate atherosclerosis development and vessel injury-induced neointimal formation. Endothelial cell migration and the underlying mechanisms were studied using in vitro cell culture models.

Results:

In the prospective population-based Bruneck Study, the level of plasma DKK3 was inversely related to carotid artery intima-media thickness and 5-year progression of carotid atherosclerosis independently from standard risk factors for atherosclerosis. Experimentally, we analyzed the area of atherosclerotic lesions, femoral artery injury-induced reendothelialization, and neointima formation in both DKK3^-/-/apolipoprotein E^-/- and DKK3^+/+/apolipoprotein E^-/- mice. It was demonstrated that DKK3 deficiency accelerated atherosclerosis and delayed reendothelialization with consequently exacerbated neointima formation. To explore the underlying mechanisms, we performed transwell and scratch migration assays using cultured human endothelial cells, which exhibited a significant induction in cell migration in response to DKK3 stimulation. This DKK3-induced migration activated ROR2 and DVL1, activated Rac1 GTPases, and upregulated JNK and c-jun phosphorylation in endothelial cells. Knockdown of the ROR2 receptor using specific siRNA or transfection of a dominant-negative form of Rac1 in endothelial cells markedly inhibited cell migration and downstream JNK and c-jun phosphorylation.

Conclusions:

This study provides the evidence for a role of DKK3 in the protection against atherosclerosis involving endothelial migration and repair, with great therapeutic potential implications against atherosclerosis.

Exposure of Induced Pluripotent Stem Cell-Derived Vascular Endothelial and Smooth Muscle Cells in Coculture to Hemodynamics Induces Primary Vascular Cell-Like Phenotypes

Human induced pluripotent stem cells (iPSCs) can be differentiated into vascular endothelial (iEC) and smooth muscle (iSMC) cells. However, because iECs and iSMCs are not derived from an intact blood vessel, they represent an immature phenotype. Hemodynamics and heterotypic cell:cell communication play important roles in vascular cell phenotypic modulation. Here we tested the hypothesis that hemodynamic exposure of iECs in coculture with iSMCs induces an in vivo‐like phenotype. iECs and iSMCs were cocultured under vascular region‐specific blood flow hemodynamics, and compared to hemodynamic cocultures of blood vessel‐derived endothelial (pEC) and smooth muscle (pSMC) cells. Hemodynamic flow‐induced gene expression positively correlated between pECs and iECs as well as pSMCs and iSMCs. While endothelial nitric oxide synthase 3 protein was lower in iECs than pECs, iECs were functionally mature as seen by acetylated‐low‐density lipoprotein (LDL) uptake. SMC contractile protein markers were also positively correlated between pSMCs and iSMCs. Exposure of iECs and pECs to atheroprone hemodynamics with oxidized‐LDL induced an inflammatory response in both. Dysfunction of the transforming growth factor β (TGFβ) pathway is seen in several vascular diseases, and iECs and iSMCs exhibited a transcriptomic prolife similar to pECs and pSMCs, respectively, in their responses to LY2109761‐mediated transforming growth factor β receptor I/II (TGFβRI/II) inhibition. Although there are differences between ECs and SMCs derived from iPSCs versus blood vessels, hemodynamic coculture restores a high degree of similarity in their responses to pathological stimuli associated with vascular diseases. Thus, iPSC‐derived vascular cells exposed to hemodynamics may provide a viable system for modeling rare vascular diseases and testing new therapeutic approaches. Stem Cells Translational Medicine2017;6:1673–1683

ZEB1-induced tumourigenesis requires senescence inhibition via activation of DKK1/mutant p53/Mdm2/CtBP and repression of macroH2A1

OBJECTIVE

Understand the role of ZEB1 in the tumour initiation and progression beyond inducing an epithelial-to-mesenchymal transition.

DESIGN

Expression of the transcription factor ZEB1 associates with a worse prognosis in most cancers, including colorectal carcinomas (CRCs). The study uses survival analysis, in vivo mouse transgenic and xenograft models, gene expression arrays, immunostaining and gene and protein regulation assays.

RESULTS

The poorer survival determined by ZEB1 in CRCs depended on simultaneous high levels of the Wnt antagonist DKK1, whose expression was transcriptionally activated by ZEB1. In cancer cells with mutant TP53, ZEB1 blocked the formation of senescence-associated heterochromatin foci at the onset of senescence by triggering a new regulatory cascade that involves the subsequent activation of DKK1, mutant p53, Mdm2 and CtBP to ultimately repress macroH2A1 (H2AFY). In a transgenic mouse model of colon cancer, partial downregulation of Zeb1 was sufficient to induce H2afy and to trigger in vivo tumour senescence, thus resulting in reduced tumour load and improved survival. The capacity of ZEB1 to induce tumourigenesis in a xenograft mouse model requires the repression of H2AFY by ZEB1. Lastly, the worst survival effect of ZEB1 in patients with CRC ultimately depends on low expression of H2AFY and of senescence-associated genes.

CONCLUSIONS

The tumourigenic capacity of ZEB1 depends on its inhibition of cancer cell senescence through the activation of a herein identified new molecular pathway. These results set ZEB1 as a potential target in therapeutic strategies aimed at inducing senescence.

Dickkopf-3 Ablation Attenuates the Development of Atherosclerosis in ApoE-Deficient Mice

BACKGROUND

Dickkopf-3 (DKK3) is a negative regulator of the Wnt/β-catenin signaling pathway, which is involved in inflammation. However, little is known about the relationship between DKK3 expression and the progression of atherosclerosis. The aim of the present study was to define the role of DKK3 and its potential mechanism in the development of atherosclerosis.

METHODS AND RESULTS

Immunofluorescence analysis showed that DKK3 was strongly expressed in macrophages of atherosclerotic plaques from patients with coronary heart disease and in hyperlipidemic mice. The expression level was significantly increased in atherogenesis. DKK3-/-ApoE-/- mice exhibited a significant decrease in atherosclerotic lesions in the entire aorta, aortic sinus, and brachiocephalic arteries. Transplantation of bone marrow from DKK3-/-ApoE-/- mice into lethally irradiated ApoE-/- recipients resulted in a reduction of atherosclerotic lesions, compared with the lesions in recipients transplanted with ApoE-/- donor cells, suggesting that the effect of DKK3 deficiency was largely mediated by bone marrow-derived cells. A reduction in the necrotic core size, accompanied by increased collagen content and smooth muscle cells and decreased accumulation of macrophages and lipids, contributed to the stability of plaques in DKK3-/-ApoE-/- mice. Furthermore, multiple proinflammatory cytokines exhibited marked decreases in DKK3-/-ApoE-/- mice. Finally, we observed that DKK3 ablation increased β-catenin expression in the nuclei of macrophages both in vivo and in vitro.

CONCLUSIONS

DKK3 expression in macrophages is involved in the pathogenesis of atherosclerosis through modulation of inflammation and inactivation of the Wnt/β-catenin pathway.

Isolation and Culture of Vascular Smooth Muscle Cells from Small and Large Vessels

Primary culture of vascular smooth muscle cells is an important in vitro model for the dissection of molecular mechanisms related to a specific physiological or pathological response at the cellular level. Cultured cells also provide an excellent model to study cell biology. This chapter describes a user-friendly and practical protocol for isolation of vascular smooth muscle cells from small and large vessels by enzymatic dissociation, which can be applied to vessels from different species, including rodents and humans.

Vascular diseases await translation of blood vessels engineered from stem cells

The discovery of human induced pluripotent stem cells (hiPSCs) might pave the way toward a long-sought solution for obtaining sufficient numbers of autologous cells for tissue engineering. Several methods exist for generating endothelial cells or perivascular cells from hiPSCs in vitro for use in the building of vascular tissue. We discuss current developments in the generation of vascular progenitor cells from hiPSCs and the assessment of their functional capacity in vivo, opportunities and challenges for the clinical translation of engineered vascular tissue, and modeling of vascular diseases using hiPSC-derived vascular progenitor cells.