Mobilization of bone marrow-derived Nkx2-5(+) cardiac progenitor cells under condition of acute myocardial ischemia.
ABSTRACT The present study aimed to observe the morphological distribution of bone marrow (BM)-derived Nkx2-5(+) cardiac progenitor cells (CPCs) in bone marrow niche and evaluate the effect of acute myocardial ischemia (AMI) on the mobilizion of BM-derived Nkx2-5(+) CPCs. Animal models of BALB/c mouse AMI, cerebral and hind-limb ischemia were established. Nanogold labeling method, immunofluorescence and Western blot were used to identify the distribution of BM-derived Nkx2-5(+) CPCs and the expressions of Nkx2-5 protein in peripheral blood and BM after AMI. Meanwhile, in different ischemia organ models and after AMD3100 (SDF-1/CXCR4 antagonist) pretreatment in AMI model, Nkx2-5 protein expressions in peripheral blood were also assayed. Nkx2-5(+) CPCs were found to locate in cavitas medullaris. The percentage of Nkx2-5(+) CPCs in blood increased immediately after AMI. Nkx2-5 protein expression in peripheral blood was also upregulated at the timepoint of 24 h post-AMI (P<0.01) and kept stable without further enhancement from day 1 to day 7 post-AMI. In BM, Nkx2-5 protein expression was upregulated immediately after AMI and downregulated afterwards (P<0.01). After AMD3100 pretreatment in AMI group, Nkx2-5 protein expression was significantly inhibited in peripheral blood (P<0.05). In cerebral and hind-limb ischemia models, Nkx2-5 protein expressions were significantly lower than that in AMI group (P<0.01), but with no significant difference to control group. These results suggest that Nkx2-5(+) CPCs are physiologically resident in BM and AMI initiates mobilization of BM-derived Nkx2-5(+) CPCs in a predominant organ-specific manner. In the procedure of mobilization, SDF-1 may play a critical role in a chemoattracted manner.
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ABSTRACT: Fibroblasts can be reprogrammed by ectopic expression of reprogramming factors to yield induced pluripotent stem (iPS) cells that are capable of transdifferentiating into diverse types of somatic cell lines. In this study, we examined if functional cardiomyocytes (CMs) can be produced from mouse cardiac fibroblasts (CFs), using iPS cell factor-based reprogramming. CFs were isolated from Oct4-GFP-C57 mice and infected with a retrovirus expressing the Yamanaka reprogramming factors, Oct4, Sox2, Klf4, and c-Myc to reprogram the CFs into a CF-iPS cell line. Primary mouse embryonic fibroblast cells (MEFs) were used as a control. We found that the dedifferentiated CF-iPS cells showed similar biological characteristics (morphology, pluripotent factor expression, and methylation level) as embryonic stem cells (ESs) and MEF-iPS cells. We used the classical embryoid bodies (EBs)-based method and a transwell CM co-culture system to simulate the myocardial paracrine microenvironment for performing CF-iPS cell cardiogenic differentiation. Under this simulated myocardial microenvironment, CF-iPS cells formed spontaneously beating EBs. The transdifferentiated self-beating cells expressed cardiac-specific transcription and structural factors and also displayed typical myocardial morphology and electrophysiological characteristics. CFs can be dedifferentiated into iPS cells and further transdifferentiated into CMs. CFs hold great promise for CM regeneration as an autologous cell source for functional CM in situ without the need for exogenous cell transplantation in ischemic heart disease.Cell biochemistry and biophysics 12/2012; 66. DOI:10.1007/s12013-012-9487-2 · 2.38 Impact Factor