Fig. 3.

Metabolic ⁶⁴Cu-radiolabeling of cytotoxic T lymphocytes (CTLs) and in vivo small-animal PET imaging. a In vitro stability of ⁶⁴Cu-labeled NOTA-DBCO in PBS and FBS (n = 3). b Binding specificity of ⁶⁴Cu-labeled NOTA-DBCO with Ac₄ManNAz-incubated CTLs (n = 4). The results are expressed as percentage administered dose per million cells (%AD/10⁶ cells). c Cell viability of unlabeled CTLs or ⁶⁴Cu-labeled CTLs (⁶⁴Cu-CTLs) after culturing for various times (n = 5). d ⁶⁴Cu retention on the surfaces of the CTLs after incubating in cell culture medium for various times (n = 4). e DNA damage of untreated CTLs (control), CTLs treated with 3 or 6 Gy of X-ray irradiation (RT), or ⁶⁴Cu-labeled CTLs (3, 8, 24, and 48 h after labeling) as measured using γH2AX immunofluorescence staining (n = 7). f Small-animal PET images of ⁶⁴Cu-labeled control-CTLs and ⁶⁴Cu-labeled OVA-specific CTLs (OVA-CTLs) in B16-OVA tumor-bearing C57BL/6 mice at 4, 12, 24, and 36 h postinjection. Tumors are indicated by white arrows. Data are presented as mean ± SD. *, P < 0.05