造血干细胞移植是治疗恶性血液病最有效的方法，但造血干细胞来源少、扩增困难，成为限制该疗法临床应用的瓶颈之一，因此持续深入的研究造血发育调控机制，实现有限来源造血干细胞的有效扩增就尤为必要。造血干细胞来源于成血成血管干细胞，随着胚胎发育，不停的变换造血位点。不同分化水平的造血干细胞表面抗原、免疫表型和粘附分子的均有一定程度的差异。Cdh5既表达在成血成血管干细胞，又表达于血管干细胞和造血干细胞，表达量和作用模式与造血发育正向调控因子hoxb4高度相似。一定浓度的Hoxb4，能有效扩增HSC而不影响其分化。本课题组前期研究发现cdh5表达水平与hoxb4作用机制有高度的关联性，本课题拟利用斑马鱼胚胎体外发育、透明，可直接动态监测造血发育过程、造血调控网络与人类高度保守的特点，研究cdh5在造血发育过程中的功能，明确其与hoxb4的调控关系，为有效扩增造血干细胞提供理论基础。

Hematopoietic stem cell transplantation is the most effective method for the treatment of hematological malignancies，but less source of hematopoietic stem cells, difficulty of amplification,  It is one of the bottlenecks to limit the clinical application of this therapy. Therefore, the hematopoietic developmental regulation mechanism is studied in depth. Hematopoietic stem cells are derived from hemangioblasts, and with the development of embryos, the hematopoietic site is changed. Different levels of hematopoietic stem cell surface antigen, immunophenotype and adhesion molecules have a certain degree of difference.Cdh5 expression in hemangioblasts, vascular stem cells and hematopoietic stem cells, the expression and function pattern similar to hematopoietic development positive regulation factor hoxb4 height. A certain concentration of Hoxb4, amplification effectively HSC without affecting its differentiation.Our previous studies found that cdh5 with hoxb4 expression level mechanism has a high degree of correlation.Zebrafish embryo development in vitro, transparent, can be directly dynamic monitoring of hematopoietic development process, hematopoietic regulation network and human highly conservative characteristics,this subject intends to research the function of cdh5 in the process of hematopoietic development, clarify the regulation between hoxb4 and cdh5,by transgenic zebrafish. provide a theoretical basis for the effective expansion of hematopoietic stem cells.