Videoscopic fluorescence diagnosis of peritoneal and thoracic metastases from human hepatoblastoma in nude rats

Photodynamic Diagnosis and Therapy for Peritoneal Carcinomatosis from Gastrointestinal Cancers: Status, Opportunities, and Challenges

Selective accumulation of a photosensitizer and the subsequent response in only the light-irradiated target are advantages of photodynamic diagnosis and therapy. The limited depth of the therapeutic effect is a positive characteristic when treating surface malignancies, such as peritoneal carcinomatosis. For photodynamic diagnosis (PDD), adjunctive use of aminolevulinic acid- protoporphyrin IX-guided fluorescence imaging detects cancer nodules, which would have been missed during assessment using white light visualization only. Furthermore, since few side effects have been reported, this has the potential to become a vital component of diagnostic laparoscopy. A variety of photosensitizers have been examined for photodynamic therapy (PDT), and treatment protocols are heterogeneous in terms of photosensitizer type and dose, photosensitizer-light time interval, and light source wavelength, dose, and dose rate. Although several studies have suggested that PDT has favorable effects in peritoneal carcinomatosis, clinical trials in more homogenous patient groups are required to identify the true benefits. In addition, major complications, such as bowel perforation and capillary leak syndrome, need to be reduced. In the long term, PDD and PDT are likely to be successful therapeutic options for patients with peritoneal carcinomatosis, with several options to optimize the photosensitizer and light delivery parameters to improve safety and efficacy.

The role of minimally invasive surgery in pediatric solid tumors

During recent years, minimally invasive surgery (MIS) has become the standard approach for various operations in infants and children. MIS in pediatric thoracic and abdominal tumors is a controversial approach in the surgical management of childhood cancer. Meanwhile, more and more oncological biopsies and resections are being performed laparoscopically or thoracoscopically. Despite its increasing role in pediatric tumor surgery, the different national and international multicenter trial groups have not yet implemented MIS within guidelines and recommendations in most of the current treatment protocols. An increasing number of retrospective reports describes a potential role of MIS in the management of different pediatric oncological entities. Over the time, there has been a diverse development of this approach with regard to the different neoplasms. Nevertheless, there is a lack of prospective randomized trails assessing MIS. This still represents a requirement for evidence-based medicine and judging the advantages and disadvantages of this approach. The purpose of this state-of-the-art article is to review the current literature to describe the application of MIS in pediatric solid tumors.

Photodynamic diagnosis for detection of peritoneal carcinomatosis

BACKGROUND

Peritoneal carcinomatosis is the dissemination of cancer in the peritoneal cavity secondary to abdominal or extra-abdominal malignancies. Accurate assessment of the disease's burden is a challenge because of the complexity of the peritoneal cavity and the small size of the metastatic nodules. Photodynamic diagnosis (PDD) is an emerging technology in tumor diagnosis. A photosensitizer is administered, which is preferentially taken up by cancer cells. The photosensitizer emits fluorescence when exposed to a light of a specific wavelength. This helps distinguish cancer from normal tissues.

METHODS

We systematically reviewed the evidence for using PDD in detecting peritoneal carcinomatosis in both animal and human literature. Both Medline and EMBASE databases were searched (November 2014). The titles and the abstracts of all retrieved citations were inspected, and the full articles of the relevant articles were obtained.

RESULTS

A total of 12 human and 18 animal studies were included. Clinical studies have shown PDD to be a safe modality with no significant adverse effects. It increases the detection of malignant peritoneal nodules by 21%-34% in comparison with white light alone. The sensitivity and specificity of PDD were reported at 83%-100% and 95%-100%, respectively. These findings were supported by multiple animal studies, which have shown an increase in the sensitivity of tumor detection when using PDD (72%-91%) in comparison with white light alone (39%).

CONCLUSIONS

PDD is a promising modality, which improves the detection of peritoneal carcinomatosis lesions. Further research, however, should investigate the impact of PDD on the patients' therapeutic management and final outcomes.

Successful in vivo tumor visualization using fluorescence laparoscopy in a mouse model of disseminated alveolar rhabdomyosarcoma

BACKGROUND

Surgery for rhabdomyosarcoma is challenging due to a lack of clear delineation between tumor and surrounding tissue. Mutilating surgery can be necessary in difficult tumor localizations. Therefore, novel diagnostic and therapeutic modalities are required. The aim of this study was to evaluate the in vivo tumor detection of RMS using fluorescence laparoscopy and to analyze the efficacy of hypericin-induced photodynamic therapy in a mouse model.

METHODS

Seventeen NOD/LtSz-scid IL2Rγnull-mice were divided into four groups. In group 1, mCherry-expressing tumor cells and in group 2-4 non-transfected tumor cells were xenotransplanted. Three weeks later, one fluorochrome per group (ICG, ICG-cetuximab, hypericin) was injected. Fluorescence laparoscopy was carried out and tumors were resected using fluorescence guidance. In the hypericin group, photodynamic therapy was performed using blue light and apoptosis was evaluated by TUNEL test.

RESULTS

A clear discrimination between healthy and tumor tissue was feasible by fluorescending properties with mCherry expressing tumor cells and after injection of hypericin. No fluorescence was detected in mice injected with ICG and ICG-labeled cetuximab. Hypericin photodynamic therapy induced apoptosis of tumor cells after exposure to blue light.

CONCLUSIONS

Intraoperative photodynamic diagnosis was feasible using mCherry-transfected tumor cells or hypericin. Additionally, intraoperative photodynamic therapy was possible and effective.

Animal models of extracranial pediatric solid tumors

Animal models, including xenografts, models of metastatic invasion, syngeneic models and transgenic models, are important tools for basic research in solid pediatric tumors, while humanized animal models are useful for novel immunotherapeutical approaches. Optical and molecular imaging techniques are used for in vivo imaging and may be used in conjunction with alternative treatment approaches, including photodynamic therapy. The aim of this review is to highlight the various animal models that may be used for basic research in pediatric solid tumors.

Successful establishment of an orthotopic hepatoblastoma in vivo model in NOD/LtSz-scid IL2Rγnull mice

Investigation of hepatoblastoma in experimental conditions contributes relevantly to a detailed understanding of tumor biology and the investigation of new treatment approaches. Most systematical analyses currently use subcutaneous xenografts. We established a reproducible intrahepatic model with the hepatoblastoma-cell lines HuH6 and HepT1. The cells were stably transfected with a plasmid vector encoding for Gaussia luciferase. HuH6 and HepT1 were injected intrasplenically in NOD/LtSz-scid IL2Rγnull mice. Mice were splenectomized in order to avoid intrasplenical tumor growth. Multifocal intrahepatic tumor growth was observed in 85% (11/13) of HuH6 tumors and 55% (5/9) of HepT1 tumors. Serum Alpha-fetoprotein and Gaussia luciferase increased 5 weeks after tumor-cell inoculation. Tumors were detected by MRI at this time point. Immunhistochemical analysis such as vascularity (CD31), proliferation index (Ki-67), cytokeratin 7 and distribution of β -catenin in intrahepatic tumors were different to subcutaneous tumors. We established a reproducible xenograft model for intrahepatic hepatoblastoma growth with a high tumor incidence. Monitoring of tumor cell viability was optimized by measuring GLuc. This model enables further experimental investigations of HB in a more physiological milieu as emphasized by the β-catenin distribution.

In vitro and in vivo evaluation of photodynamic techniques for the experimental treatment of human hepatoblastoma and neuroblastoma: preliminary results

PURPOSE

The purpose of this study was to test the susceptibility of human hepatoblastoma and neuroblastoma cells to photodynamic diagnostics (PDD) and photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) as a photosensitizer.

METHODS

Cell cultures of human hepatoblastoma (HuH6) and neuroblastoma (MHH-NB-11) were incubated with 5-ALA at increasing concentrations to measure the cellular kinetics of photosensitization. After optimizing incubation parameters, the cell cultures were then irradiated with increasing light doses and cell viability was measured by CTB assay. Human fibroblastic cells served as controls. So far, only the hepatoblastoma cell line has been tested in vivo. After injection of HUH6 cells in immunoincompetent rats, the efficacy of PDT was assessed. Photosensitization was achieved by intraperitoneal injection of 5-ALA. The pharmacokinetics of different tissues was studied. In a second study, a PDT of implanted hepatoblastoma, liver and peritoneum was performed. The irradiated areas were excised 48 h after treatment and studied by microscopy.

RESULTS

Cell culture experiments demonstrated a selective fluorescence for both tumor lines compared to controls. The photosensitized tumor cells demonstrated marked reductions in cell viability at significantly lower irradiation doses than the fibroblasts under PDT. The specificity of fluorescence was confirmed in vivo for hepatoblastoma, and all the sensitized and irradiated tumors showed marked phototoxic necrosis.

CONCLUSION

Human hepatoblastoma and neuroblastoma demonstrate marked and specific fluorescence after the application of 5-ALA, making PDD possible. Cell death occurred in both cell lines after PDT in vitro. Additionally, hepatoblastoma was susceptible to PDT in an animal model. Further studies will be necessary to determine the role of PDT and PDD in a clinical setting.

Extracorporeal photodynamic image detection of mouse osteosarcoma in soft tissues utilizing fluorovisualization effect of acridine orange

Various imaging methods have been employed for the extracorporeal detection of malignant tumors in the human body, such as scintigraphy and PET; however, none is sufficiently accurate and all are also very expensive. To resolve these issues, we attempted to develop a new imaging technique of photodynamic diagnosis (PDD) with acridine orange (AO). AO has the ability to rapidly and specifically accumulate in malignant tumors and emit brilliant green fluorescence after blue light excitation. In this study, we investigated the feasibility of PDD utilizing the fluorovisualization effect of AO, for the extracorporeal detection of mouse osteosarcoma inoculated into the soft tissues. At 2 h after intravenous administration of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 mg/kg AO, the tumor and the surrounding normal tissues were illuminated by blue light. The visual fluorescence contrast and ratio (X) of the difference in fluorescence intensity between the tumor and the surrounding normal tissues were evaluated using a high-resolution digital camera equipped with an absorption filter. In addition, the fluorescence contrast was also detected sequentially at 0.5, 1, 2, 3, 6 and 12 h after intravenous administration of AO at 1.0 mg/kg. The results revealed that the optimal condition for clear detection of the tumor was evaluation 2 h after intravenous injection of AO at 0.1 mg/kg, because it provided the best visual contrast on the digital images, and the fluorescence intensity as well as the value of X were higher as compared to the values under other conditions of dose and timing. Based on the results of an acute toxicity study of AO, the estimated LD50 of this substance following intravenous administration was 27.30 mg/kg. In conclusion, we believe that PDD using AO administered intravenously may be feasible for the detection of human musculoskeletal sarcomas in the soft tissues at extremities, and this technique might be a less invasive, less expensive, quicker and more accurate imaging modality than other previously reported imaging methods for this purpose.