Genome Editing and Cardiac Regeneration.

Although the field of cardiac regeneration is relatively young, it is progressing rapidly with technological advancements. Genome editing tools are allowing researchers to creatively influence signaling pathways to be able to shed light on them and are important for addressing certain issues and limitations associated with in vitro and in vivo aspects of cardiac regeneration, such as imaging and immune rejection. In this chapter, the pathways involved in cardiac regeneration will be highlighted, and the role of gene-editing tools in endogenous and exogenous approaches to regenerate injured myocardium is discussed.

Migration despite stabilization of an embolized transcatheter heart valve: A word of caution.

This case report describes an initially stabilized transcatheter heart valve that embolized in the ascending aorta, leading to a postprocedural acute type A aortic dissection.

Snare or Scalpel: Challenges of Intracardiac Cement Embolism Retrieval.

Intracardiac cement embolism after percutaneous vertebroplasty is a rare, but dangerous, complication, and guiding principles for its management are not well described. The management of this present case of intracardiac cement embolism offers insight to facilitate the treatment decision-making process in symptomatic patients requiring extraction.

Glioblastoma cell populations with distinct oncogenic programs release podoplanin as procoagulant extracellular vesicles.

Vascular anomalies, including local and peripheral thrombosis, are a hallmark of glioblastoma (GBM) and an aftermath of deregulation of the cancer cell genome and epigenome. Although the molecular effectors of these changes are poorly understood, the upregulation of podoplanin (PDPN) by cancer cells has recently been linked to an increased risk for venous thromboembolism (VTE) in GBM patients. Therefore, regulation of this platelet-activating protein by transforming events in cancer cells is of considerable interest. We used single-cell and bulk transcriptome data mining, as well as cellular and xenograft models in mice, to analyze the nature of cells expressing PDPN, as well as their impact on the activation of the coagulation system and platelets. We report that PDPN is expressed by distinct (mesenchymal) GBM cell subpopulations and downregulated by oncogenic mutations of EGFR and IDH1 genes, along with changes in chromatin modifications (enhancer of zeste homolog 2) and DNA methylation. Glioma cells exteriorize their PDPN and/or tissue factor (TF) as cargo of exosome-like extracellular vesicles (EVs) shed from cells in vitro and in vivo. Injection of glioma-derived podoplanin carrying extracelluar vesicles (PDPN-EVs) activates platelets, whereas tissue factor carrying extracellular vesicles (TF-EVs) activate the clotting cascade. Similarly, an increase in platelet activation (platelet factor 4) or coagulation (D-dimer) markers occurs in mice harboring the corresponding glioma xenografts expressing PDPN or TF, respectively. Coexpression of PDPN and TF by GBM cells cooperatively affects tumor microthrombosis. Thus, in GBM, distinct cellular subsets drive multiple facets of cancer-associated thrombosis and may represent targets for phenotype- and cell type-based diagnosis and antithrombotic intervention.

Genetic and epigenetic regulation of cancer coagulome - lessons from heterogeneity of cancer cell populations.

Cancer-associated thrombosis (CAT) is a morbid, potentially life threatening and biologically impactful paraneoplastic state. At least in part, CAT is likely driven by cancer-specific mechanisms the nature of which is still poorly understood, hampering diagnostic, prophylactic and therapeutic efforts. It is increasingly appreciated that cancer-specific drivers of CAT include a constellation of oncogenic mutations and their superimposed epigenetic states that shape the transcriptome, phenotype and secretome of cancer cell populations, including the repertoire of genes impacting the vascular and coagulation systems. High-grade brain tumours, such as glioblastoma multiforme (GBM) represent a paradigm of locally initiated haemostatic abnormalities that propagate systemically, likely through circulating mediators, such as extracellular vesicles and soluble factors. Reciprocally, CAT impacts the biology of cancer cells and may drive tumour evolution. The constituent, oncogene-transformed cancer cell populations form complex ecosystems, the intricate architecture of which has been recently revealed by single cell sequencing technologies. Amidst this phenotypic heterogeneity, several alternative pathways of CAT may exist both between and within individual tumours and their subtypes, including GBM. Indeed, different contributions of cells expressing key coagulant mediators, such as tissue factor, or podoplanin, have been identified in GBM subtypes driven by oncogenic mutations in EGFR, IDH1 and other transforming genes. Thus, a better understanding of cellular sources of CAT, including dominant cancer cell phenotypes and their dynamic shifts, may help design more personalised approaches to thrombosis in cancer patients to improve outcomes.

Oncogenes and Clotting Factors: The Emerging Role of Tumor Cell Genome and Epigenome in Cancer-Associated Thrombosis.

There are emerging linkages between biological and genetic aspects of cancer progression and the mechanisms of cancer-associated thrombosis. It is argued that reciprocal influences between cancer cells, their associated vascular stroma, and the hemostatic system may shape the mechanism of coagulopathy. In this regard, glioblastoma multiforme offers a paradigm where the prevalent occurrence of local microthrombosis and peripheral venous thromboembolism can be linked to the profiles of oncogenic driver mutations and their impact on the expression of coagulation-related genes (coagulome). These relationships can be recapitulated in cellular models of glioblastoma, where the expression of tissue factor, podoplanin, and the release of procoagulant microparticles (extracellular vesicles) remains under the control of oncogenic pathways (epidermal growth factor receptor variant III, isocitrate dehydrogenase 1). These pathways define molecular subtypes of glioblastoma that express differential coagulomes. Moreover, single-cell sequencing of glioblastoma samples reveals a combinatorial rather than common profile of both subtype markers and coagulation-related genes. Based on these emerging observations, the authors suggest that cancers may operate as coagulant composites, where individual cells and their dominant populations express different procoagulant phenotypes, resulting in the net impact on the hemostatic system. They suggest that relating these mechanisms to clinical presentations of thrombosis may facilitate a more causality-based, personalized, and possibly cancer-specific thromboprophylaxis and treatment.

Single cell coagulomes as constituents of the oncogene-driven coagulant phenotype in brain tumours.

Molecular profiling of human cancers revealed a startling diversity in disease-causing mechanisms superseding histological and anatomical commonalities. The emerging molecular subtypes and disease entities are often driven by distinct oncogenic pathways and their effectors, including those acting extracellularly on the vascular and coagulation systems. Indeed, several oncogenic mutations such as those affecting protein-coding genes (RAS, EGFR, PTEN, TP53) and non-coding RNA (microRNA) regulate multiple effectors of the coagulation system (coagulome), including tissue factor, protease activated receptors, clotting factors, mediators of platelet function and fibrinolysis. This is exemplified by differential coagulome profiles in the molecular subtypes of glioblastoma, medulloblastoma and other human tumours. There is mounting clinical evidence that the mutational status of cancer driver genes such as KRAS or IDH1 may influence the risk of venous thromboembolism in patients with colorectal, lung or brain cancers. Notably, single cell sequencing in glioblastoma revealed a remarkable intra-tumoural heterogeneity of cancer cell populations with regard to their individual coagulomes, suggesting a combinatorial and dynamic nature of the global pro-thrombotic phenotype. We suggest that the cellular complexity of specific cancers may define their mechanisms of interactions with the coagulation system, and the risks of thrombosis. Thus, more biologically- based, disease-specific and personalized approaches may be needed to diagnose and manage cancer-related thrombosis.