小鼠胚胎背主动脉发育过程中内皮和平滑肌标志物表达时相及其变化

Expression and changes of endothelial and smooth muscle cell markers in dorsal aorta during the development of mouse embryo

目的:观察小鼠胚胎发育过程中背主动脉胎肝激酶1、α-平滑肌肌动蛋白的表达时相,初步探讨背主动脉内皮和平滑肌细胞的形成及其可能起源。方法:实验于2006-01/2007-01在解放军沈阳军区总医院全军心血管病研究所心内科完成。①实验材料:昆明种小白鼠50只,体质量20～22g,其中雌鼠30只。②实验方法:将雌鼠分别放入公鼠笼内过夜、交配,从怀孕第8.5天开始获取胚胎,在雌鼠怀孕第8.5～18.5天,每一时间点取10个小鼠胚胎。③实验评估:对胎鼠组织切片分别行苏木精-伊红染色,观察背主动脉形态学变化;免疫组织化学染色法观察内皮细胞标志物胎肝激酶1、CD31、Ⅷ因子相关抗原,α-平滑肌肌动蛋白表达变化及其相互关系。结果:①胚胎8.5～9.5d胎鼠背主动脉由单层细胞构成,呈胎肝激酶1、CD31阳性,α-平滑肌肌动蛋白、Ⅷ因子相关抗原阴性。②胚胎10.5d胎鼠背主动脉仍为单层细胞,但胎肝激酶1、CD31、Ⅷ因子相关抗原、α-平滑肌肌动蛋白均呈阳性。③胚胎11.5d背主动脉管壁发育为多层,内层细胞呈胎肝激酶1阳性、α-平滑肌肌动蛋白阴性,外层细胞呈胎肝激酶1阴性而α-平滑肌肌动蛋白阳性,血管与周围间充质无明显分界,背主动脉管壁周围可见散在α-平滑肌肌动蛋白阳性细胞。④11.5d之后,背主动脉管壁平滑肌细胞数量增多且由不规则型转变为纺锤型,内层内皮细胞继续呈胎肝激酶1阳性、α-平滑肌肌动蛋白阴性,外层平滑肌细胞胎肝激酶1阴性、α-平滑肌肌动蛋白阳性,血管与周围间充质分界清楚,背主动脉血管周围无散在α-平滑肌肌动蛋白阳性细胞。结论:胚胎背主动脉的平滑肌细胞可能最早起源于胎肝激酶1、CD31阳性细胞,后期可能来源于周围间充质细胞的募集分化。

AIM：To observe the expression regularity of fetal liver kinase-1 （FIk-1） and smooth muscle α-actin （SM α-actin） in the dorsal aorta during the development of mouse embryo, and to investigate initially the formation and origin of endothelium and smooth muscle cells of the dorsal aorta. METHODS： The experiment was performed in the Department of Cardiology, Cardiovascular Research Institute, General Hospital of Shenyang Military Area Command of Chinese PLA from January 2006 to January 2007. ①Thirty female Kunming mice （20-22 g） were mated with male mice （20-22 g） ovemight. The embryos were harvested on day 8.5 after pregnancy, 10 embryos at each time point from the 8.5^th day to 18.5^th day. ②Morphological changes of the dorsal aorta of mouse embryos were observed in sections stained with hematoxylin and eosin, and the expression of endothelial markers FIk-1, CD31, factor Ⅷ-related antigen and smooth muscle cell marker SM α-actin and their correlation were investigated by immunohistochemical method. RESULTS： ①From 8.5 to 9.5 days, the monolayer cells-formed dorsal aorta expressed FIk-1 and CD31, but not SM α-actin and factor Ⅷ-related antigen.②FIk-1, CD31, factor Ⅷ-related antigen and SM α-actin were co-expressed in monolayer cells-formed dorsal aorta on day 10.5. ③The dorsal aorta wall consisted of multilayer cells at 11.5^th day. Endothecium cells expressed FIk-1 instead of SM α-actin; meanwhile, exothecium cells expressed SM α-actin instead of FIk-1. There was no clear boundary between the dorsal aorta wall and the surrounding mesenchymal cells. Some scattered SM α-actin-positive cells could be observed around the dorsal aorta.④After 11.5 days, smooth muscle cells of the dorsal aorta grew in number and transformed from irregular cells into spindle-shaped cells. FIk-1 remained positive in endothelial cells, and SM α-actin in smooth muscle cells. There was a clear boundary between the dorsal aorta wall and the surrounding mesenchymal tissue. No SM α-actin-positive cells could be seen surrounding the dorsal aorta. CONCLUSION： The eadiest derivation of the smooth muscle cells of the embryonic dorsal aorta may be from FIk-1, CD31-positive cells, and from recruitment and differentiation of the surrounding mesenchymal cells in the later period.