心血管系统发育

1、Development of Cardiovascular system & Regenerative MedicineDevelopment of Cardiovascular system & Regenerative Medicine第1页Content of studyPart one. Development of blood vesselPart two. Development of heartPart three. Myocardial regeneration 第2页PrefaceThe cardiovascular system is a completly closed

2、circulating pipeline. The heart is the center of various organs and tissues. All the organs and tissues are connected by blood vessels, in which blood flow. The cardiovascular system is the first system that derived from mesoderm as early as week 3 during the development. It includes the heart and t

3、he vascular system, which constitutes artery, vein and blood capillary. The cardiovascular system plays an important role in the different stages of development.p216第3页The function in different phage of development Nutrients for the development of embryo Postnatal survival第4页1. Vasculogenesis 2. Ang

4、iogenesis3. The formation of primary vascular system4. The stage of vasculogenesis and angiogenesis5. Factors participate in vasculogenesis and angiogenesis6. The separation of artery and vein7. Fetal blood circulationPart one. Development of blood vessel第5页1. Vasculogenesis(1) Process of vasculogen

5、esis Blood islandp230angioblastblood islandendothe-lial cellprimativ-e blood cellendothelial tubeprimativ. endothel. network15-16d of human embryo第6页vasculogenesis：In the embryonic stage, precursors of vascular cells and blood cells which derived from mesoderm aggregate in blood island. Then the vas

6、cular precursor cells differentiate into vascular endothelial cells and form primitive vascular network. de novo blood vessel formation, such as the primary vascular plexus in yolk sac and the vassels in liver and spleen et. al.p230第7页(2) Angioblast growthFrom the fact that there is close relation i

7、n time and space of hematopoietic cells and endothelial cells during the process of development, it is speculated that they probably come from a precursor cell called angioblast. 第8页Free vascular cells connected into loose cord like structure, which is the result of integration between blood island.

8、 It is an in situ assembly of cord like blood vassel. Endothelial cells initially formed the main vessels similar to the capillary network of blood vessel network, eventually they assembled into mature vascular network.vasculogenesis = Angioblast growth第9页第10页(1) angiogenesis：The process of generati

9、ng new blood vessels from existed blood vessels. It is the basic steps needed for many physiological and pathological reactions. Angiogenesis occurs in wound healing, endometrial cyclical changes, tumor, myocardial infarction and diabetes et al.the organs without angioblast migration into, such as t

10、he brain and the spinal cord.2. Angiogenesisp230第11页(2) Methods of angiogenesis Sprouting Intussusception or splitting a new blood vessel is created by splitting of an existing blood vessel in twoprimative cardiovascular systemprimative endothelial networkfuse, thickeningdiminish, atrophyp230第12页3.

11、The formation of primary vascular systemp231第13页4. The stage of vasculogenesis and angiogenesis Vasculogenesis creates the primary network of vascular endothelial cells that will become major blood vessels. Later, angiogenesis remodels this network into the small new blood vessels or capillaries tha

12、t complete the childs circulatory system. Postnatal vasculogenesis begins from the differentiation of endothelial stem/progenitor cells. Endothelial stem/progenitor cells may derive from different cells, such as angioblast in blood, bone marrow progenitors or resident stem cells. The process of angi

13、ogenesis is the same as that in embryonic stage. p236第14页The new blood vessels fromation in the adult also includes two processes: angiogenesis and vasculogenesisNeovascularization encompasses both angiogenesis and vasculogenesis. Angiogenesis represents the classic paradigm for new vessel growth, a

14、s mature, differentiated ECs break free from their basement membrane and migrate as well as proliferate to form sprouts from parental vessels. Vasculogenesis involves participation of BM-derived EPCs, which circulate to sites of neovascularization where they differentiate in situ into mature ECs. Gr

15、owth factors, cytokines, or hormones released endogenously in response to tissue ischemia, or administered exogenously for therapeutic, act to promote EPC proliferation, differentiation, and migrate from BM (via the peripheral circulation) to neovascular foci. p236第15页5. Vasculogenesis/Angiogenesis

16、regulators p232第16页The inhibitors and activators第17页 In the research of tumor angiogenesis, some cytokines and small molecules has been found. Among them, the most important activators of angiogenesis are VEGF and bFGF.第18页（1）VEGF VEGF is a 46KD hot-stable polypeptide, which is isolated from bovine

17、pituitary follicular stellate cell conditioned medium by Ferrara in 1989. VEGF-VEGFR and vasculogenesis/angiogenesisVEGF is a growth factor having specific effects on vascular endothelial cells. Because VEGF can enhance vascular permeability, it is also known as vascular permeability factor. It belo

18、ngs to the vascular endothelial growth factor family. Other members include VEGF-B, placental growth factor (PIGF), VEGF-C and VEGF-D.p232第19页第20页（2）VEGFRspecific to VEGF, high affinity membrane receptor, belong to the tyrosine kinase family membersTypical embedded transmembrane protein, including 7

19、 extracellular immunoglobulin region, a transmembrane region and intracellular region of TK.Include VEGFR -1 (Flt-1), VEGFR-2 (KDR/Flk-1) and VEGFR-3. VEGFR-3 distributed in lymphatic endothelial cells, VEGFR-1 and VEGFR-2 express on vascular endothelial cells.p232第21页p232(3) Function of VEGF/VEGFRV

20、EGF is a mitogen and survival factor of microvascular endothelial cells. VEGFB, VEGFC, VEGFD, PLGFFlk-1 is the main mediator which mediate VEGF targeting on endothelial cell. Flk-1 expresses on embryonic stage.Structure and location of expressing of Flt-1 are similar to Flk-1. Flt-1 still express af

21、ter birth. 第22页Ang-1/Tie-2 and the wall of blood vesselTie-2 is a receptor tyrosine kinase expressing in vascular endothelium. Except for the vasculogenesis and angiogenesis, Tie-2 is necessary for vascular remodeling. Tie-2 is the receptor of Ang -1 and Ang -2. The Ang-1s function is to promote the

22、 formation of the vascular wall, to ensure the integrity and stability of new vessels. Ang-2 only exists in the trimming process.p232第23页Perivascular mesenchymal cells produce Ang-1, which is surrounded by Tie-2 located on the surface of endothelial cells. Under the interaction of Ang-1 and Tie-2, s

23、ignal molecule in endothelial cells was stimulated and released, such as platelet-derived growth factor (PDGF). The release of PDGF induced mesenchymal cells migrating to vascular endothelium. When endothelial cells and mesenchymal cells contact, endothelial cells release transforming growth factor

24、beta (TGF-) to transform the mesenchymal cells into vascular smooth muscle cells or pericytes (a cell close to the capillary wall outside).p232 figure第24页(4) FGF & FGFR(5) PDGF-beta & PDGFRIn addition, ECM and cell adhesion molecule are also play important role in angiogenesis. The components of ECM

25、, such as fibronectin, collegen, intergrin and vascular endothelial cadherin, all take part in the proliferation and migration of endothelial cells.p233第25页VEGF blockade differentiation of endothelial cells into vein through activation of Notch signaling pathwaythe molecular markers of vein is suppr

26、essed, meanwhile the expression of artery molecular markers is activated, when the Notch signal is activatedephrinB2 express in arterial endothelial cells and its receptor EphB4 express in the venous endothelial cells6. The separation of artery and vein第26页7. Fetal blood circulationp237第27页Part two.

27、 Development of heart1. Development of heart2. Mechanism of the heart development 3. Heart defect第28页p21617d27-37d22d第29页1. Development of heart(1) formation of the cardiac tubep216第30页p216第31页p216第32页p217第33页p217第34页(2) The evolution and transformation of the heartthe formation of S shape heartp219

28、第35页(3)Partitioning of the heart partitioning of atrialventricular canalp219第36页 partitioning of atriump219第37页p219第38页 partitioning of ventricle p221第39页 partitioning of truncus and bulbus cordis动脉干心球p221第40页TinmanIn the begining of 1990, Bodmer reported the first heart-development relative gene, t

29、inman, which expresses in cardiogenic mesoderm and plays role in cardiac precursor specialization.2. Mechanism of the heart development (1) specification of cardiomyocyte第41页Nkx2.5Nkx2.5 is the first specialized gene expressing in the cardiogenesis region and is a marker of the earliest cardiac prec

30、ursor. It can activate the transformation of cardiac precursor cells to cardiomyocyte. Unlike Drosophila Tinman, Nkx2.5 is not required in mouse cardiac differentiation. It is possible that there are other genes involved in Nkx2.5 related functions.p223第42页BMP signal pathwayBMP is a member of the fa

31、mily of signaling molecules and is closely related to many developmental processes. It is an important heart speciafication signal and is necessary for the transformation of cardiac precursor cells into heart cells. BMP2 and BMP4 are indusor of myocardialgenesis. BMP influence the specification of t

32、he heart by co-activite with cardiac transcription factor such as GATA and FGF signal from mesoderm interaction.Early cardiogenesis of Drosophila system is dependent on Dpp (Drosophila BMP). Dpp express in the dorsal ectoderm cells during gastrulation and mesoderm migration process and is one of the

33、 important signal molecule to induce heart dorsal ectoderm. An important target of Dpp gene is tinman. BMP is the indusor of Nkx2.5.p222第43页MEF2 myocyte enhancer factor 2. Mamalian MEF2 family includes MEF2AD. The MEF2C is one of the earlist expressed molecular marker in cardiac progenitor cells. Th

34、e products of MEF2 family play role in the transcription of myocardiac specification. Nkx2.5 activates MEF2C and promote myocardial genesis. MEF2C can unpregulate the expression of Nkx2.5, BMP-4 and GATA-4.In Drosophila p222第44页serum response factor, SRFWntFGF第45页(2) Genesis of cardiac tube6 members

35、Charicteristics：DNA binding sites are composed by two zinc finger modelsGATA-1、2、3 express in heamatopoitic cellsGATA-4、5、6 express in mesoderm and endoderm tissues and regulate gene expression of these tissues. It can not act as a dominant gene for cell specialization. It only can regulate cell dif

36、ferentiation and specialization by interact with other other transcription fact. Such as, N-cadherin/GATA-4, MAPK/GATA-4, ERK/GATA-4GATA familyp224第46页Embryonic cardiac development was blocked by GATA-6 knockout in Xenopus 第47页miles aparttwo bilateral hearts：The mutants of the genes prevent cardiac

37、precursor cell migration to the midline to form the heart tube, but to form two cardiac phenotypes in both sides of the body.mesp1 fibronectin miles apartp224第48页Wild typemiles apart mutantcardiogenic mesoderm 第49页(3) heart looping heart tube is the first asymatric structure of the embryoHand bHLH (

38、basic helix-loop-helix) familyHeart tube is the first asymmetry structure formed in the body and HAND molecules played pivital role in translating the asymmetry molecular signaleHAND and dHANDNkx2-5 & MEF-2第50页Nkx2.5、MEF2In early stage of heart development, Nkx2.5 interacts with Tbx5 and regulate he

39、art looping with other transcripts such as MEF2 and HAND.Shh（sonic hedgehog）Hh protein play important role in the construction on polirity of left-right axis in the embryo and is the key step of heart looping.p225第51页Nodal、Lefty & PitxLefty:左撇子p225第52页(4) The maturity of the heartthe differentiation

40、 of endocardiumendocardium：the endothelial layer which is formed inside the heart and be continious with other vascular system role：be continious with other vascular system, transfer signals to the myocardium cells to form trabecular, be involved in the differentiation of myocardial cells to Purkinj

41、e fiber, formation of endocardial cushion structuresource：the endocardium and vesscular endothelium play similar role, but the sources of these two cell layers are different. Endocardium derives from heart precursor cells. Under the role of endoderm, endocardium is gathered and is sandwiched in the

42、heart tube. Clotch is correlated with the genesis of endocardium.第53页the differentiation and maturity of myocardiumThe classic transcription factors such as Nkx2.5, MEF2C and GATA4 interact with each other and play role in myocardium differentiation. The functional damage of a single gene can not ab

43、olish the differentiation of myocardium completely, but can change the bilateral fusion of heart tube in the area of middle line et al. Nkx2.5, Hand and MEF2c deficiency will lead to ventricular dysplasia, and lead to early embryonic death.第54页TBX5（Homo sapiens T-box 5）Holt-Oram Syndrome: Heart sept

44、al defect & upper limb deformityAnteroposterior radiograph of the chest shows an enlarged cardiac silhouette (black arrow) and enlarged pulmonary vessels indicative of shunt vascular. 第55页(5) Formation of endocardial cushionsa. migration and transformation of endocardial endothelial cells N-CAMb. th

45、e induction from myocardial cells adherons，ES-130c. TGF- TGF-d. others NRG-1, insulin-like growth factor I, hepatocyte growth factor produced by myocardial cells, endothelin, nitric oxide, angiotensin also play a role in the formation of valve.第56页Different TBX5 mutants show different phenotypes. So

46、me mutants cause serious heart defects, and some other mutants only cause a trace heart defect. The study of these functional defects has important significance for clinical analysis. GATA-4 interact with TBX5, both of them are involved in the formation of heart septum. GATA-4 G296S：The mutation lea

47、ds to reduced binding affinity with DNA and reduced transcriptional activation of GATA-4. Further, it was found that GATA-4 mutations lead to a loss of interaction between GATA-4 and TBX5. When artificially introduced TBX5 missense mutation, the mutant also led to the disappearance of interaction be

48、tween GATA-4 and TBX5 and caused a similar cardiac septal defects.第57页(6) The occurrence of epicardiumThe epicardium originated from the epicardial serosa. The interaction between alpha 4 integrin and vascular cell adhesion molecule (VCAM-1) is indispensable to the transfer of original the epicardia

49、l cells to the heart. Alpha 4 integrin is expressed by epicardial, VCAM-1 is expressed by myocardial. Knockdown of alpha 4 integrin or VCAM-1, mice can form normal epicardial initially, but following the further development, the epicardium lost, and the heart can not be covered.第58页(5) development o

50、f outflow trackPax-3 is a transcription factor widely expressed in neural tube and neural crest migration, which is important to the migration of neural crest cells to cardiac outflow. Homeobox gene Msx2 is a direct downstream effector of Pax3. Pax3 surpress Msx2 expression. In Pax-3 mutants, neural

51、 crest cells move out from normal neural tube, but can not migrate to the aortic sac and result in the formation of persistent truncus arteriosus.第59页3. Heart malformationIncidence of neonatal heart defect is 1/100Classification of heart malformation: cyanosis, no cyanosis.Acropachy and growth disor

52、der. 第60页1malformation of outflow track第61页第62页（1） persistentncus of arteriosus The truncus is failed to be divided into pulmonary artery and aorta artery for the reason of serious defect of the septum. The truncus rides on the left and right ventricle, which results in pulmonary hypertension. On th

53、e other hand, the baby shows cyanosis after birth due to the unenough oxygen in circulating blood .In the migrating neural crest cells, pax3 gene mutation leads to persistent truncus arteriosus. Wnt, BMP and VEGF signal pathways are related with the seperating of truncus.第63页（2）transposition of the large arteriesPulmonary artery locates in front of the aorta and connected with left ventricle. The septum is straight, not spiral. Often accompanied by atrioventricular septal defect or patent du