Figure 1. ⁸⁹Zr-oxine labeling does not alter cellular phenotype and survival.

A. ⁸⁹Zr-labeling (13.7–22.2 kBq/10⁶ cells) did not alter the expression of lineage marker in BM cells or Sca-1 and CD117 expression of lineage marker⁻ cells. Representative flow cytometry data of 3 independent experiments and the average of all data (white: control, black: ⁸⁹Zr-labeled) are shown. Approximately 4.2% of lineage negative cells were HSCs expressing both sca-1 and CD117 (n=6). B. BM cells not labeled (open circle) and labeled at 13.7 (filled circle) and 28.8 (cross) kBq/10⁶ cells were cultured without exogenous cytokines. Live cell number decreased in a similar manner in all the groups (n=3, 13.7 kBq/10⁶ cellls: p=0.0156 and 0.0016 at day 1 and 2, 28.8 kBq.10⁶ cells : p<0.0001, p=0.0186 and 0.0011 on day 2, 3 and 4, vs control). C. Cell associated ⁸⁹Zr activity, with decay correction, showed slight decrease at the early time points and then almost plateaued (n=3). No significant difference was observed between the two labeling doses. D. The ⁸⁹Zr-labeled cells (13.7 kBq/10⁶ cells, black) showed slightly higher fraction of apoptotic and/or necrotic cells (i.e. annexin V⁺ and/or PI⁺ cells) by flow cytometry analysis compared to non-labeled control (white) on day 2, but the difference was not significant (70–83% of total cells, n=3). E. Expression of Ki67 in live cells on day 2 was negligible (n=3).