Figure 2.

Radiolabelling efficiency and radiochemical stability of intraluminal-labelled B16F10 exosomes. (A) Radiolabelled exosomes ([¹¹¹In]-Exo_B16) were purified from excess [¹¹¹In]Trop complex by gel filtration (Sepharose® CL-2B). Eight 500 µl fractions were collected and the radioactivity for each fraction and the column itself post-purification was measured by gamma counting, and are expressed as the percentage of activity relative to the initial activity added to the column. Radiolabelling efficiency was calculated as the sum of % radioactivity recovered from F1 and F2. (B) Radiolabelled exosomes were incubated in either PBS or 50% serum for 24 h at 37°C, and then passed through the same column as (A). Eight 500 µl fractions were collected and the radioactivity for each fraction and the column itself (FC) post-purification was measured using gamma counter, and are expressed as the percentage of activity relative to the activity of the sample added to the column. Radiochemical stability was calculated as the sum of % radioactivity recovered from F1 and F2. Values are expressed as mean ± SD, where n=3. Statistical analysis was done on F1 and F2 (p* < 0.05, p*** <0.001).