Fluorescence Imaging Using Enzyme-Activatable Probes for Real-Time Identification of Pancreatic Cancer.

INTRODUCTION: Radical resection is the only curative treatment for pancreatic cancer, which is a life-threatening disease. However, it is often not easy to accurately identify the extent of the tumor before and during surgery. Here we describe the development of a novel method to detect pancreatic tumors using a tumor-specific enzyme-activatable fluorescence probe. METHODS: Tumor and non-tumor lysate or small specimen collected from the resected specimen were selected to serve as the most appropriate fluorescence probe to distinguish cancer tissues from noncancerous tissues. The selected probe was sprayed onto the cut surface of the resected specimen of cancer tissue to acquire a fluorescence image. Next, we evaluated the ability of the probe to detect the tumor and calculated the tumor-to-background ratio (TBR) by comparing the fluorescence image with the pathological extent of the tumor. Finally, we searched for a tumor-specific enzyme that optimally activates the selected probe. RESULTS: Using a library comprising 309 unique fluorescence probes, we selected GP-HMRG as the most appropriate activatable fluorescence probe. We obtained eight fluorescence images of resected specimens, among which four approximated the pathological findings of the tumor, which achieved the highest TBR. Finally, dipeptidyl-peptidase IV (DPP-IV) or a DPP-IV-like enzyme was identified as the target enzyme. CONCLUSION: This novel method may enable rapid and real-time visualization of pancreatic cancer through the enzymatic activities of cancer tissues.

Timing for removing prophylactic drains after liver resection: an evaluation of drain removal on the third and first postoperative days.

BACKGROUND: Conventionally, drains are removed from postoperative day (POD) 7 to POD 14 at our institute after hepatectomy (control group). This study was conducted to evaluate the outcomes of drain removal in the early postoperative period. METHODS: Recently, we defined criteria for the early removal of drains: (I) a drain-fluid bilirubin level of below 3 mg/dL; (II) a drain discharge volume of less than 500 mL/day; and (III) no macroscopic signs of bleeding or infection. For patients meeting these criteria, drains were removed on POD 3 between January 2012 and February 2013 (POD 3 group) and on POD 1 between February and December 2013 (POD 1 group). The outcomes of these groups were then retrospectively compared. RESULTS: The median duration of the postoperative hospital stay was shorter in the POD 3 group (11 days) than in the control group (14 days) (P<0.0001). The incidence of drain infection was lower in the POD 3 group (1.2%) than in the control group (5.7%). Meanwhile, the incidences of bile leakage and complications were higher in the POD 1 group than in the POD 3 group. However, the incidences were almost the same when patients whose drains were actually removed on the predefined POD were compared. The intraoperative findings were also considered when removing the drains. CONCLUSIONS: Drain removal on POD 3 may reduce the length of the postoperative hospital stay and the incidence of drain infection without impairing safety. To remove drains safely on POD 1, however, the intraoperative findings should also be considered.

A novel liver-specific fluorescent anti-cancer drug delivery system using indocyanine green.

Indocyanine green (ICG) accumulates only in hepatocytes and their malignant counterpart, hepatocellular carcinoma (HCC). We have developed ICG-conjugated anti-cancer drugs and noted their significant accumulation in HCC cells both in vitro and in vivo. ICG-conjugated gemcitabine was less toxic to normal cells and it had superior anti-tumor action compared to gemcitabine alone in a subcutaneous tumor xenograft. ICG conjugation can provide a novel fluorescent drug delivery system for treatment of liver cancer and this system can be used to both diagnose and treat HCC.

Near-infrared photothermal/photodynamic therapy with indocyanine green induces apoptosis of hepatocellular carcinoma cells through oxidative stress.

Indocyanine green (ICG) is a photothermal agent, photosensitizer, and fluorescence imaging probe which shows specific accumulation in hepatocellular carcinoma (HCC) cells. We recently developed a photodynamic therapy (PDT) using ICG and near-infrared (NIR) laser as a new anti-cancer treatment for HCC. However, the molecular mechanism underlying this effect needs to be elucidated. HuH-7 cells, a well-differentiated human HCC cell line, were transplanted subcutaneously into BALB/c-nu/nu mice for in vivo experiment. ICG was administered 24 h before NIR irradiation. The irradiation was performed at three tumor locations by 823-nm NIR laser on days 1 and 7. The temperature of HuH-7 xenografts increased to 48.5 °C 3 minutes after ICG-NIR irradiation start. Reactive oxygen species (ROS) production was detected after ICG-NIR irradiation both in vitro and in vivo. There was certain anti-tumor effect and ROS production even under cooling conditions. Repeated NIR irradiation increased the cell toxicity of ICG-NIR therapy; the mean tumor volume on day 9 was significantly smaller after ICG-NIR irradiation compared to tumor without irradiation (87 mm3 vs. 1332 mm3; p = 0.01) in HCC mice xenografts model. ICG-NIR therapy induced apoptosis in HCC cells via a photothermal effect and oxidative stress. Repeated ICG-NIR irradiation enhanced the anti-tumor effect.