A downtrend of mesenchymal cells derived from the second heart field and cardiac neural crest in the outflow tract of cx43 knockout embryonic mouse heart / 中国组织工程研究

ABSTRACT

BACKGROUND: Cx43 plays an important role in human congenital heart disease. However, there is still no consistent conclusion about the formation mechanism of cardiac malformation in Cx43 knockout mouse embryos. OBJECTIVE: To investigate the cardiac development defects and the migration and differentiation of progenitor cells of the second heart field and cardiac neural crest in Cx43 knockout mouse embryo. METHODS: Serial sections of Cx43 gene knockout homozygous (Cx43-/-) mouse and Cx43 wild-type (Cx43+/+) mouse embryos from embryonic day (ED) 10 to ED13 were made for immunohistochemical and immunofluorescent staining, and three-dimensional reconstruction of the heart. RESULTS AND CONCLUSION: (1) In Cx43 gene knockout mouse embryos at ED10-ED11, Isl1 positive second heart field cells in the ventral mesenchyme of the foregut extended through the area between the bilateral arch arteries to the dorsal wall of pericardial cavity. Meanwhile, Isl1 positive cells in the core mesenchyme of the branchial arches were continuous with those in the dorsal wall of pericardial cavity and the distal wall of the outflow tract. At ED13, the distribution of Isl1 positive cells was observed in the wall of the ascending aorta and pulmonary trunk as well as the wall of the left and right outflow tracts of the septated ventricles. However, compared with wild-type mouse embryos, fewer Isl1 positive second heart field cells were found in Cx43 gene knockout mouse embryos (P < 0.01). (2) During ED10 to ED11, Ap2α positive neural crest cells were still found in the wall of the arch artery and the dorsal and ventral walls of the aortic sac in Cx43 gene knockout mouse embryos, but the number of neural crest cells was less than that of wild-type mouse embryos (P < 0.01). (3) These results indicate that the migration path and distribution pattern of Isl1 positive second heart field cells and Ap2α positive cardiac neural crest cells are similar between the Cx43 gene knockout and wild-type mouse embryos, but the number of two kinds of migrating cells is reduced after Cx43 gene knockout. This suggests that in addition to cardiac neural crest derived cells, the decrease of second heart field progenitor cells might be involved in the formation of outflow tract malformations in Cx43 knockout mouse embryos.