Photodynamic diagnosis of gastric cancer using HPPH-CD

Gastric cancer is associated with a poor prognosis and is the fourth most common carcinoma and the second leading cause of cancer-related mortality worldwide due to its late-stage diagnosis and recurrence. New strategies are urgently needed to improve this condition. 2-[10-Hexyloxyethyl]-2-devinyl pyropheophorbide-(HPPH)-cyanine dye (CD) mediated photodynamic diagnosis (PDD) has attracted great attention as a relatively new modality for tumor diagnosis. However, the efficacy of HPPH-CD-PDD on gastric cancer is poorly understood. The present study evaluates the effectiveness of PDD on gastric cancer diagnosis using HPPH-CD. We first evaluated the imaging potential of HPPH-CD on ICR mice bearing S180 subcutaneous tumors to make a preliminary definition of the ideal conditions for diagnosis. Subsequently, animal models with gastric cancer were established by giving 3,4-benzopyrene (B(a)P) to KM mice and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) to Wistar rats. The fluorescence signals of the stomach were then detected after HPPH-CD delivery, followed by imaging under a standard bright field. Furthermore, the tumors were collected, fixed and processed for histologic review. We found that subcutaneous S180 tumors and orthotopic primary gastric tumors could be easily visualized with fluorescence imaging after the delivery of HPPH-CD, and all malignant lesions with strong fluorescence were histologically confirmed. These results revealed the potential of HPPH-CD as a novel photosensitizer for the enhanced visualization of tumors in gastric cancer.