PTPRC and acute myocardial infarction: However, the highest levels of the CD45–CD34 + CD271+ cells seemed to be present on day 2 (see Fig. 1), which is a similar result to the one received by Iso et al. (2012), in acute myocardial infarction patients, where the CD45 low/−CD34 + CD271+ cell counts peaked on day 3 and then declined gradually up to day 7.