Rate of cell division in vascular lesions is related to Tcf21 expression.

<p>A) EdU staining was performed in <i>Tcf21</i>^{<i>iCre/+</i>}, <i>ROSA</i>^<i>tdT/+</i>, <i>Ldlr</i>^<i>-/-</i> mice treated with tamoxifen and EdU and placed on HFD for 9, 12, or 15 weeks prior to tissue collection. Co-localization of <i>Tcf21</i> tdT fluorescence (red) and EdU fluorescent staining (green) allowed identification of the sdividing cells that were expressing <i>Tcf21</i> (yellow arrows, image from 12 week timepoint). B) The ratio of <i>Tcf21</i>+EdU+ cells compared to total <i>Tcf21</i>+ cells was significantly increased at 12 weeks of diet, consistent with a proliferative response in <i>Tcf21</i>+ cells. Comparison of percentage differences between 0 and 9 weeks, and from 9 to 12 weeks approached significance, <i>P</i> = 0.06; there was not a statistical difference between 12 and 15 weeks, <i>P</i> = 0.11. C, D) Rates of cell division in vascular lesions were compared between <i>Tcf21</i>^{<i>lacZ/+</i>}, <i>ApoE</i>^<i>-/-</i> animals and <i>ApoE</i>^<i>-/-</i> animals on HFD for 20 wks by quantifying the relative number of dividing cells identified by EdU fluorescence compared to the total number of cells identified by DAPI fluorescence. EdU fluorescence (green) was merged with red pseudocolored DAPI fluorescence, yellow arrows indicate yellow nuclei that are positive for both EdU and DAPI fluorescence. E) A statistically significant decrease in this percentage in <i>Tcf21</i>^{<i>lacZ/+</i>}, <i>ApoE</i>^<i>-/-</i> animals compared to <i>ApoE</i>^<i>-/-</i> animals suggested a correlation between <i>Tcf21</i> expression and rate of cell division in the vascular lesions. In, intima; M, media; Ad, adventitia; FC, fibrous cap, Lu, lumen.