Cardiovascular Biology

Angiogenesis is the formation and remodelling of new blood vessels and capillaries from growth of pre-existing blood vessels. It normally occurs during wound healing and embryonic development, but is also required for tumour growth and metastasis in cancer.And it mainly includes degradation of vascular basement membrane during activation;Activation, proliferation and migration of vascular endothelial cells;Reconstruction and formation of new blood vessels and blood vessel networks. In a word, it is a complex process involving a variety of molecules in a variety of cells.

Cardiac stem cells are thought to be a quiescent, heart-resident population that can reenter the cell cycle following injuries such as acute myocardial infarction. Cardiac stem cells isolated from the myocardium have self-renewal capabilities in vitro and the ability to differentiate in vivo into all three major cardiac cell types: cardiomyocytes, vascular smooth muscle cells, and endothelial cells. In addition, in vivo lineage tracing studies suggest that another population of cardiac progenitor cells expressing TBX18 and WT1 reside in the epicardium. The ability to identify and analyze cardiac stem cells presents researchers with the potential to promote endogenous myocardial regeneration and prevent congestive heart failure.

Coagulation is the process of formation of a fibrin clot. Coagulation is an important part of hemostasis, the process of blood clotting and then the subsequent dissolution of the clot, following repair of the injured tissue. Coagulation begins almost instantly after an injury to the blood vessel has damaged the endothelium. When the endothelium is damaged, the von Willebrand factor (vWF) is exposed to blood and recruits Factor VIII, collagen, and other coagulation factors. Circulating platelets adhere to exposed collagen, release the contents of their granules, and aggregate at the site of injury, forming a temporary, loose platelet plug. To insure stability of the initially loose platelet plug, proteins in the blood plasma, called coagulation factors or clotting factors, respond in a complex cascade to form fibrin clots.The coagulation cascade has two pathways, the intrinsic pathway (also known as the contact activation pathway), and the extrinsic pathway (also known as the tissue factor pathway), which lead to fibrin formation. The coagulation system overlaps with the immune system. Coagulation can physically trap invading microbes in blood clots. Also, some products of the coagulation system can contribute to the innate immune system by their ability to increase vascular permeability and act as chemotactic agents for phagocytic cells. In addition, some of the products of the coagulation system are directly antimicrobial. Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or clotting (thrombosis).

In response to a complex integration of signaling pathways involving BMP, FGF, Nodal, and Wnt, pluripotent stem cells are specified to become cells of the mesodermal lineage. Early mesodermal lineage specification can be characterized by the expression of specific markers, such as the transcription factors Brachyury, Snail, and TBX6. In addition to the activation of mesoderm-inducing transcriptional programs, pluripotency genes required for self-renewal are silenced via epigenetic mechanisms.

Hemangioblasts are the embryonic precursors of hematopoietic stem cells (HSCs), giving rise to committed hematopoietic progenitors such as lymphoids, thymocytes, myeloids, granuloctes-monocytes, megakaryocytes-erythrocytes, and mast cells. The concept that the hemangioblast exists was first introduced more than 80 years ago, and it has since gained support from studies that the hematopoietic and endothelial lineages share expression of a number of genes, such as CD34, VEGF R2/Flk-1, SCL, CBFA2/RUNX1, and GATA-1.

Cholesterol is an extremely important biological molecule that has roles in membrane structure as well as being a precursor for the synthesis of the steroid hormones, the bile acids, and vitamin D. Both dietary cholesterol, and that synthesized de novo, are transported through the circulation in lipoprotein particles. The same is true of cholesteryl esters, the form in which cholesterol is stored in cells. Due to its important role in membrane function, all cells express the enzymes of cholesterol biosynthesis.

Vascular smooth muscle cell is the major cell type in blood vessels. Dysfunction of vascular smooth muscle cells is an important cause of vascular diseases, for example, atherosclerosis, hypertension, and circulatory shock. Vascular smooth muscle cells are phenotypically plastic, capable of switching between two major phenotypes — contractile/differentiated phenotype and invasive/proliferative phenotype in response to environmental clues.