<p>Secondary colony forming efficiency of BMSCs plated at clonal density (A) or high density (B) from 5 donors. Data are represented as mean +/− S.D. of colony forming units for each donor done in triplicates. Note the lack of a statistically different change in number of colonies in SPION-labeled BMSCs (solid colored bars), Student t test, p>0.5. A similar lack of a statistically different change in the number of colonies were found when the secondary colony forming efficiency experiments from 5 donors were repeated independently by two other scientists.</p
