In recent years, several kinds of cardiac progenitor cells have been identified and isolated from heart tissue. These cells showed differentiation potential into cardiomyocytes, smooth muscle cells, and endothelial cells in vitro and in vivo. Morphogenetic events are tightly regulated during development to determine cell destiny and reshape the embryonic lineage. In this study, we directly compared the characteristics of rat fetal cardiac progenitor cells (rFCPCs) isolated from the chamber formation stage at embryonic day 12 (E12) and at the septation stage of E15. Both kinds of rFCPCs expressed mesenchymal stem cell markers (CD105, CD73, and CD29) but not CD34 and CD45. The E12 rFCPCs expressed a high level of Oct4 compared to E15 until passage 5 and showed a steep decline of Nkx2.5 expression at passage 5. However, Nkx2.5 expression at E15 was maintained until passage 5 and Oct4 expression slightly increased at passage 5. We also detected an intense staining for Oct4 antibody in E12 heart tissue sections. The average doubling time of the E12 rFCPCs from passage 3 to passage 15 was about 5 hours longer than E15. These cells could also be induced into cardiomyocytes expressing α-MHC, cTnT, cTnC, and Cx43 under cardiomyogenic culture conditions and rFCPCs at E15 showed more intense staining of α-MHC than cells at E12 by immunocytochemistry. Taken together, our results show that developmental differences between E12 and E15 may influence their properties and differentiation. Furthermore those differences should be considered when deciding on the optimal cell source for cell replacement therapy in cardiovascular regeneration.
Keywords: Cardiomyogenic differentiation; Cardiovascular regeneration; Gestation age; Rat fetal cardiac progenitor cells.