FIGURE 4 from Nanoparticle-mediated Photodynamic Therapy as a Method to Ablate Oral Cavity Squamous Cell Carcinoma in Preclinical Models

Histologic examination of intratumoral PS nanoparticle accumulation and mechanisms of PS-PDT damage in tumor-bearing mice models of oral cavity cancer. A, Brightfield images of the pathophysiology of Cal-33 xenograft tumors (top) and syngeneic MOC22 tumors (bottom). Scale bars = 250 µm. B, Imaging of PS nanoparticle intratumoral distribution using fluorescence microscopy (PS signal labeled “Pyro”) and tissue autoradiography of ⁶⁴Cu-labeled PS radioactivity in Cal-33 (top) and MOC22 (bottom) tumors. Scale bars = 1,000 µm. Note that labeling PS with ⁶⁴Cu permit radiotracing of PS pharmacokinetics in tissues and cells using radioactivity (Supplementary Fig. S1). Additional histologic images of other mouse organs are provided in Supplementary Fig. S4. C, Quantitative spatial analysis of cellular proximity of Pyro⁺ cells to CD31⁺ cells (CD31←Pyro) and of PIMO⁺ cells to CD31⁺ cells (CD31←PIMO) in Cal-33 and MOC22 tumors. Units µm. Scatter plot of individual replicates (●) with median distance identified by red line. N = 4–5 tumors/model. Additional quantitative intratumoral spatial analysis data provided in Supplementary Fig. S5. D, Histologic evidence of antitumor response in a Cal-33 xenograft tumor 72 hours after PS-PDT treatment (10 mg/kg, 24 hours DLI, 100 J/cm², 100 mW/cm²). Scale bars = 500 µm. E, Quantification of histopathologic photodamage 72 hours post-treatment of Cal-33 tumor xenograft using apoptosis marker cleaved caspase-3. Units %. Mean ± SD. N = 3–4 tumors/treatment group. Additional statistical analysis is provided in Supplementary Table S8. H&E, hematoxylin and eosin (stain for tissue microanatomy and cellular morphology); CD31, cluster of differentiation 31 (marker for vascular/endothelial cell); PIMO, pimonidazole (fluorescent marker for tissue hypoxia); DAPI, 4′,6-diamidino-2-phenylindole (nuclear DNA fluorescent marker); Pyro (fluorescent marker for PS nanoparticles); ⁶⁴Cu tissue autoradiography (intensity marker for ⁶⁴Cu-labeled PS concentration in tissues); �lls Marker⁺ (percent of nucleated cells positive for marker of interest in tumor cross-section); TUNEL (DNA fragmentation marker).