The Study Of Photodynamic Therapy Effects Based On Shell-less Chick Chorioallantoic Membrane Tumor Model

The tumor treatment has long been an important research issue. Compared with many other approaches, the photodynamic therapy (PDT) attracts more research attentions in recent years. Since the growth of tumor cell relies on the surrounding vessels to provide nutrition, while one of the key effects of PDT in tumor treatment is its effect of vascular damage, PDT has become the research focus by many researchers. However, one limitation is that the mechanism behind destroying the vessels and prohibiting the neovascularization is not clear so far. This limitation is partly due to the unsuitableness of current animal models and the unsatisfactory performance of existing imaging methods. Aimed at these two limitations during PDT research, based on the ACC-M-GFP cell suspensions with stable and highly expressible GFP on shell-less chorioallantoic membrane (CAM), the tumor model is built and its growth and location are observed by using fluorescence imaging technique. In this study, by using the CAM tumor model, the PDT is applied on the tumor and the surrounding vessels, together with the laser speckle contrast imaging (LSCI) to real-time monitor the variance of the vessels during PDT, such as vessel diameter, blood velocity, etc. The vessel perfusion can then be calculated, and the degree of vessel damage is also evaluated. The results prove: 1) It's very convenience to transplant human tumor on chicken embryo. Such operation is suitable for the study of the vascular damage induced by PDT and the growth and neovascularization of tumor cell suspensions. In addition, the operation can also be used to evaluate the angiogenic activity. 2) It's suitableness to use LSCI technique to evaluate the vessel damage because it can not only measure the vessel diameter change, but also can estimate the blood velocity change and perfusion change. Such capability of LSCI technique provides a new hemodynamic method for the research of PDT effect on vessel. Our research demonstrates that the CAM tumor model is an excellent model to examine the vascular damage effect of PDT. With the aids of fluorescent imaging technique, the CAM can locate the tumor region more precisely so that the growth of tumor could be monitored. In addition, due to the characteristic of photosensitizer, the irradiation region on CAM can also be identified. Using LSCI to obtain the blood perfusion change in PDT irradiation region enables real-time monitoring of the vascular damage effect by PDT, which has obvious the significance in developing new photosensitizer and discovering better photodynamic dosage for tumor treatment.