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Human osteosarcoma 143B cells were previously stably transfected with an α v integrin green flourescent protein (GFP) vector. 143B cells expressing α v integrin-GFP were transplanted orthotopically in the tibia of transgenic nude mice ubiquitously expressing red fluorescent protein (RFP). The primary tumors acquired RFP-expressing stroma and were passaged orthotopically in the tibia in noncolored nude mice, which maintained the RFP stroma. The interaction of α v integrin-GFP expression in 143B cells with RFP-expressing host stromal cells was observed by confocal microscopy using the Olympus FV1000. Collagen fibers were imaged simultaneously in reflectance mode. The RFP-expressing stroma included cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) which persisted even 3 weeks after passage to nontransgenic nude mice. CAFs expressing RFP were aligned between collagen fibers and cancer cells expressing α v integrin-GFP. Six weeks after transplantation, pulmonary metastases expressing α v integrin-GFP could be identified. TAMs expressing RFP accompanied metastasized osteosarcoma cells expressing α v integrin-GFP in the lung. The current study demonstrates the importance of α v integrin interaction with stromal elements in osteosarcoma., (© 2018 Wiley Periodicals, Inc.)

We previously described the development of a highly-invasive, triple-negative breast cancer (TNBC) variant using serial orthotopic implantation of MDA-MB-231 human breast cancer in nude mice. The isolated variant is highly invasive in the mammary gland and metastasized to lymph nodes in 10 of 12 mice compared with 2 of 12 of the parental cell line. OBP-401 is a telomerase-dependent cancer-specific, green fluorescent protein (GFP)-expressing adenovirus. OBP-401 was used to infect parental MDA-MB-231P cells and high-metastatic MDA-MB-231H and MDA-MB-231HLN isolated from a lymph node metastasis and MDA-MB-231HLM isolated from a lung metastasis. Time-course imaging showed that OBP-401 labeled MDA-MB-231HP, MDA-MB-231HLN, and MDA-MB-231HLM cells more brightly than MDA-MB-231 parental cells. OBP-401 killed MDA-MB-231H, MDA-MB-231HLN, and MDA-MB-231HLM cells more efficiently than MDA-MB-231P parental cells. These results indicate that OBP-401 could infect, label and then kill high-metastatic MDA-MB-231 more efficiently than low-metastatic MDA-MB-231.

Human osteosarcoma cells with an α v integrin green fluorescent protein (GFP) fusion gene were previously established and imaged in vitro and in vivo. In the present study, we imaged the interaction of α v integrin-GFP in osteosarcoma cells and collagen fibers in vascular-trafficking osteosarcoma emboli in nude mice. Human 143B osteosarcoma cells, expressing α v integrin-GFP, were injected by a vascular route in an abdominal skin flap in nude mice. Osteosarcoma cells were fluorescently imaged in the epigastric cranialis vein in the abdominal skin flap by confocal microscopy. Collagen fibers were imaged in reflectance mode. At early stages of tumor embolus-formation, cancer cells adhered firmly to each other, diffusely expressing α v integrin-GFP. Two weeks after injection, collagen fiber scaffolds were visualized at the margins of tumor emboli or within them. Four weeks after injection, cancer cells invading from emboli were strongly expressing α v integrin-GFP, and were aligned along collagen fibers. The results suggest α v integrin and collagen fiber scaffolds are important for tumor embolus formation, which are potential seeds of metastasis. J. Cell. Biochem. 118: 26-30, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

There are two major types of mouse xenograft models of cancer: subcutaneous implantation and orthotopic implantation. Subcutaneous transplant models are widely used with both cancer cell lines and human-tumor specimens. Recently, subcutaneous models of patient tumors, termed patient-derived xenographs (PDX) have become highly popular and have acquired such names as "Avatar" and "Xenopatients." However, such s.c. models rarely metastasize and are therefore not patient-like. In contrast, orthotopic models have the capability to metastasize. If intact fragments of tumor tissue are implanted by surgical orthotopic implantation (SOI), the metastatic potential can match that of the donor patient. The present study images in real time, using green fluorescent protein (GFP) expression, the very different tumor behavior at the orthotopic and subcutaneous sites of human prostate cancer PC-3 in athymic nude mice. By day-2 after tumor implantation, the orthotopic tumor is already highly vascularized and the cancer cells have begun to migrate out of the tumor. In contrast, the subcutaneous tumor only begins to be vascularized by day-3 and cells do not migrate from the tumor. Angiogenesis is much more extensive in the orthotopic tumor throughout the 2-week observation period. The orthotopic PC-3-GFP tumor progresses very rapidly and distinct metastasis have appeared in lymph nodes by day-3 which rapidly appear in many areas of the abdominal cavity including portal lymph nodes by day-7. At day-14, no invasion or metastasis was observed with the s.c. tumor even when the animal was extensively explored. These results explain why orthotopic tumors mimimc clinical metastatic tumors in nude mice and why subcutaneous tumors do not. J. Cell. Biochem. 117: 2546-2551, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

We have developed a multi-color, imageable, orthotopic mouse model for individual patients with pancreatic cancer. The tumors are labeled by first passaging them orthotopically through transgenic nude mice expressing green fluorescent protein (GFP), red fluorescent protein (RFP), or cyan fluorescent protein (CFP). Passage of the tumors in these colored transgenic mice labels the stromal cells of the tumor. The cancer cells in the PDOX are labeled in situ with GFP by telomerase-dependent adenovirus OBP-401. The models are termed imageable patient-derived orthotopic xenografts (iPDOX). The tumors acquired brightly-fluorescent stromal cells from the transgenic host mice, which were stably associated with the tumors through multiple passages. The colored fluorescent protein-expressing stromal cells included cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). This model enables powerful color-coded imaging of the interaction of cancer and stromal cells during tumor progression and treatment., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

In a previous study, we developed fluorescence-guided surgery (FGS) for osteosarcoma using an orthotopic model with 143B human osteosarcoma cells expressing red fluorescent protein (RFP) implanted into the intramedullary cavity of the tibia in nude mice. The FGS-treated mice had a significantly higher disease-free survival (DFS) rate than the bright-light surgery (BLS). However, although FGS significantly reduced the recurrence of the primary tumor, it did not reduce lung metastasis. In the present study, we utilized the OBP-401 telomerase-dependent killer-reporter adenovirus, carrying green fluorescent protein (GFP), to label human osteosarcoma in situ in orthotopic mouse models. OBP-401-illuminated human osteosarcoma cell lines, 143B and MNNG/HOS cells in vitro and in vivo. OBP-401 tumor illumination enabled effective FGS of the 143B-derived orthotopic mouse model of human osteosarcoma model as well as FGS eradication of residual cancer cells after BLS. OBP-401-assisted FGS significantly inhibited local recurrence and lung metastasis after surgery, thereby prolonging DFS and overall survival (OS), achieving a very important improvement of therapeutic outcomes over our previously reported FGS study. These therapeutic benefits of FGS were demonstrated using a clinically-viable methodology of direct labeling of human osteosarcoma in situ with the OBP-401 killer-reporter adenovirus in contrast with previous reports, which used genetically engineered labeled cells or antibody-based fluorescent labels for FGS. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:836-844, 2016., (© 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Fluorescence-guided surgery (FGS) of cancer is an area of intense development. In the present report, we demonstrate that the telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 could label colon-cancer liver metastasis in situ in an orthotopic mouse model enabling successful FGS. OBP-401-GFP-labeled liver metastasis resulted in complete resection with FGS, in contrast, conventional bright-light surgery (BLS) did not result in complete resection of the metastasis. OBP-401-FGS reduced the recurrence rate and prolonged over-all survival compared with BLS. In conclusion, adenovirus OBP-401 is a powerful tool to label liver metastasis in situ with GFP which enables its complete resection, not possible with conventional BLS.

Fluorescence-guided surgery (FGS) of cancer is an area of intense current interest. However, although benefits have been demonstrated with FGS, curative strategies need to be developed. Glioblastoma multiforme (GBM) is one of the most invasive of cancers and is not totally resectable using standard bright-light surgery (BLS) or current FGS strategies. We report here a curative strategy for FGS of GBM. In this study, telomerase-dependent adenovirus OBP-401 infection brightly and selectively labeled GBM with green fluorescent protein (GFP) for FGS in orthotopic nude mouse models. OBP-401-based FGS enabled curative resection of GBM without recurrence for at least 150 days, compared to less than 30 days with BLS.

We previously described a color-coded imaging model that can quantify the length of nascent blood vessels using Gelfoam® implanted in nestin-driven green fluorescent protein (ND-GFP) nude mice. In ND-GFP mice, nascent blood vessels are labeled with GFP. We report here that osteosarcoma cells promote angiogenesis in the Gelfoam® angiogenesis assay in ND-GFP mice. Gelfoam® was initially transplanted subcutaneously in the flank of transgenic ND-GFP nude mice. Seven days after transplantation of Gelfoam®, skin flaps were made and human 143B osteosarcoma cells expressing green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in cytoplasm were injected into the transplanted Gelfoam®. The control-group mice had only implanted Gelfoam®. Skin flaps were made at days 14, 21, and 28 after transplantation of the Gelfoam® to allow imaging of vascularization in the Gelfoam® using a variable-magnification small animal imaging system and confocal fluorescence microscopy. ND-GFP expressing nascent blood vessels penetrated and spread into the Gelfoam® in a time-dependent manner in both control and osteosarcoma-implanted mice. ND-GFP expressing blood vessels in the Gelfoam® of the osteosarcoma-implanted mice were associated with the cancer cells and larger and longer than in the Gelfoam®-only implanted mice (P < 0.01). The results presented in this report demonstrate strong angiogenesis induction by osteosarcoma cells and suggest this process is a potential therapeutic target for this disease., (© 2014 Wiley Periodicals, Inc.)

The ability to visualize cancer cell mitosis and apoptosis in the brain in real time would be of great utility in testing novel therapies. In order to achieve this goal, the cancer cells were labeled with green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in the cytoplasm, such that mitosis and apoptosis could be clearly imaged. A craniotomy open window was made in athymic nude mice for real-time fluorescence imaging of implanted cancer cells growing in the brain. The craniotomy window was reversibly closed with a skin flap. Mitosis of the individual cancer cells were imaged dynamically in real time through the craniotomy-open window. This model can be used to evaluate brain metastasis and brain cancer at the subcellular level.

We have previously demonstrated that ultraviolet (UV) light treatment is effective against various types of cancer cells expressing fluorescent proteins. In order to further understand the efficacy of UV treatment of cancer cells, we determined the kinetics of focus formation by imaging of a DNA damage-response (DDR) protein after UVC irradiation of human pancreatic cancer cells. A fusion protein consisting of the DDR protein 53BP1 and green fluorescent protein (GFP) (GFP-53BP1) was used as a live-cell imaging marker for cellular response after UVC irradiation. GFP-53BP1 foci were observed after UVC irradiation of MiaPaCa-2 human pancreatic cancer cells. During live-cell imaging, GFP-53BP1 foci were observed in the cells within 15 min after UVC irradiation, and some of the foci remained stable for at least three hours. GFP-53BP1 focus formation was observed in the pancreatic-cancer cells irradiated by 25-200 J/m(2) UVC. Our results indicate that an early response to DNA damage caused by UVC irradiation can be visualized by increased GFP-53BP1 focus formation by pancreatic cancer cells.

The integrin family of proteins has been shown to be involved in the malignant behavior of cells. We report here development of a color-coded imaging model that can visualize the interaction between αv integrin linked to green fluorescent protein (GFP) in osteosarcoma cells and blood vessels in Gelfoam® vascularized after implantation in red fluorescent protein (RFP) transgenic nude mice. Human 143B osteosarcoma cells expressing αv integrin-GFP were generated by transfection with an αv integrin-GFP vector. Gelfoam® (5×5 mm) was transplanted subcutaneously in transgenic RFP nude mice. The implanted Gelfoam® became highly vascularized with RFP vessels within 14 days. Skin flaps were made at days 7, 14, 21, 28 after transplantation of Gelfoam® for observing vascularization of the Gelfoam® using fluorescence imaging. Gelfoam® is a useful tool to observe angiogenesis in vivo. 143B cells (5 × 10(5)) expressing αv integrin-GFP were injected into the Gelfoam® seven days after transplantation of Gelfoam®. Seven days after cancer-cell injection, cancer cells and blood vessels were observed in the Gelfoam® by color-coded confocal microscopy via the skin flap. The 143B cells expressing αv integrin-GFP proliferated into the Gelfoam®, which contained RFP-expressing blood vessels. Strong expression of αv integrin-GFP in 143B cells was observed near RFP vessels in the Gelfoam®. The observation of the behavior of αv integrin-GFP and blood vessels will allow further understanding of the role of αv integrin in cancer cells.

Cancer cells, with and without fluorescent protein expression, were irradiated with various doses of UVC (100, 400, and 600 J/m(2)). Dual-color Lewis lung carcinoma cells (LLC) and U87 human glioma cells, expressing GFP in the nucleus and RFP in the cytoplasm and non-colored LLC and U87 cells were cultured in 96-well plates. Eight hours after seeding, the cells were irradiated with the various doses of UVC. The resulting cell number was determined after 24 hours. Compared to non-colored LLC cells, the number of dual-color LLC cells decreased significantly due to UVC irradiation with 100 J/m(2) (p=0.003). Although there was no significant difference in the number of dual-color and non-colored U87 cells after 100 J/m(2) UVC irradiation (p=0.852), the number of dual-color U87 cells decreased significantly with respect to non-colored cells due to UVC irradiation with 400 J/m(2) and 600 J/m(2) (p=0.011 and p=0.009, respectively). Thus, both dual-color LLC and dual-color U87 cells were more sensitive to UVC light than non-colored LLC and U87 cells. These results suggest that the expression of fluorescent proteins in cancer cells can enhance photodynamic therapy (PDT) using UVC and possibly with other wavelengths of light as well.

In order to individualize and therefore have more effective treatment for pancreatic cancer, we have developed a multicolor, imageable, orthotopic mouse model for individual patients with pancreatic cancer by passaging their tumors through transgenic nude mice expressing green fluorescent protein (GFP) and red fluorescent protein (RFP). The tumors acquired brightly fluorescent stroma from the transgenic host mice, which was stably associated with the tumors through multiple passages. In the present study, pancreatic cancer patient tumor specimens were initially established in NOD.CB17-Prkdc(scid)/NcrCrl (NOD/SCID) mice. The tumors were then passaged orthotopically into transgenic nude mice ubiquitously expressing GFP and subsequently to nude mice ubiquitously expressing RFP. The tumors, with very bright GFP and RFP stroma, were then orthotopically passaged to non-transgenic nude mice. It was possible to image the brightly fluorescent tumors non-invasively longitudinally as they progressed in the non-transgenic nude mice. This non-invasive imageable tumorgraft model will be valuable to screen for effective treatment options for individual patients with pancreatic cancer, as well as for the discovery of improved agents for this treatment-resistant disease.

Tumors from pancreatic cancer patients were established in NOD/SCID mice immediately after surgery and subsequently passaged orthotopically in transgenic nude mice ubiquitously expressing green fluorescent protein (GFP). The primary patient tumors acquired GFP-expressing stroma. Subsequent liver metastases, and disseminated peritoneal metastases maintained the stroma from the primary tumor, and possibly recruited additional GFP-expressing stroma, resulting in their very bright fluorescence. The GFP-expressing stroma included cancer-associated fibroblasts and tumor-associated macrophages in both the primary and metastatic tumors. This imageable model of metastasis from a patient-tumor is an important advance over patient "tumorgraft" models currently in use, which are implanted subcutaneously, do not metastasize and are not imageable. The new imageable model of patient pancreatic cancer metastasis provides unique opportunities to identify current and novel antimetastatic therapeutics for individual patients.

The tumor microenvironment (TME) has an important influence on tumor progression. For example, we have discovered that passenger stromal cells are necessary for metastasis. In this report, we describe six different cyan fluorescent protein (CFP) multicolor TME nude mouse models. The six different implantation models were used to image the TME using multiple colors of fluorescent proteins: I) Red fluorescent protein (RFP)- or green fluorescent protein (GFP)-expressing HCT-116 human colon cancer cells were implanted subcutaneously in the CFP-expressing nude mice. CFP stromal elements from the subcutaneous TME were visualized interacting with the RFP- or GFP-expressing tumors. II) RFP-expressing HCT-116 cells were transplanted into the spleen of CFP nude mice, and experimental metastases were then formed in the liver. CFP stromal elements from the liver TME were visualized interacting with the RFP-expressing tumor. III) RFP-expressing HCT-116 cancer cells were transplanted in the tail vein of CFP-expressing nude mice, forming experimental metastases in the lung. CFP stromal elements from the lung were visualized interacting with the RFP-expressing tumor. IV) In order to visualize two different tumors in the TME, GFP-expressing and RFP-expressing HCT-116 cancer cells were co-implanted subcutaneously in CFP-expressing nude mice. A 3-color TME was formed subcutaneously in the CFP mouse, and CFP stromal elements were visualized interacting with the RFP- and GFP-expressing tumors. V) In order to have two different colors of stromal elements, GFP-expressing HCT-116 cells were initially injected subcutaneously in RFP-expressing nude mice. After 14 days, the tumor, which consisted of GFP cancer cells and RFP stromal cells derived from the RFP nude mouse, was harvested and transplanted into the CFP nude mouse. CFP stromal cells invaded the growing transplanted tumor containing GFP cancer cells and RFP stroma. VI) Mouse mammary tumor (MMT) cells expressing GFP in the nucleus and RFP in the cytoplasm were implanted in the spleen of a CFP nude mouse. Cancer cells were imaged in the liver 3 days after cell injection. The dual-color dividing MMT cells and CFP hepatocytes, as well as CFP non-parenchymal cells of the liver were imaged interacting with the 2-color cancer cells. CFP-expressing host cancer-associated fibroblasts (CAFs) were predominantly observed in the TME models developed in the CFP nude mouse. Thus, the CFP nude mouse adds another color to the pallet of the TME, allowing multiple types of color-coded cancer and stromal cells to be imaged simultaneously. The multi-colored models described in this report provide new opportunities to study the cellular interactions in the live primary and metastatic TME.

We have previously developed a telomerase-specific replicating adenovirus expressing GFP (OBP-401), which can selectively label tumors in vivo with GFP. Intraperitoneal (i.p.) injection of OBP-401 specifically labeled peritoneal tumors with GFP, enabling fluorescence visualization of the disseminated disease and real-time fluorescence surgical navigation. However, the technical problems with removing all cancer cells still remain, even with fluorescence-guided surgery. In this study, we report imaging of tumor recurrence after fluorescence-guided surgery of tumors labeled in vivo with the telomerase-dependent, GFP-containing adenovirus OBP-401.. Recurrent tumor nodules brightly expressed GFP, indicating that initial OBP-401-GFP labeling of peritoneal disease was genetically stable, such that proliferating residual cancer cells still express GFP. In situ tumor labeling with a genetic reporter has important advantages over antibody and other non-genetic labeling of tumors, since residual disease remains labeled during recurrence and can be further resected under fluorescence guidance.

Background: The use of fluorescent proteins to label tumors is revolutionizing cancer research, enabling imaging of both primary and metastatic lesions, which is important for diagnosis, staging, and therapy. This report describes the use of fluorescence laparoscopy to image green fluorescent protein (GFP)-expressing tumors in an orthotopic mouse model of human pancreatic cancer., Methods: The orthotopic mouse model of human pancreatic cancer was established by injecting GFP-expressing MiaPaCa-2 human pancreatic cancer cells into the pancreas of 6-week-old female athymic mice. On postoperative day 14, diagnostic laparoscopy using both white and fluorescent light was performed. A standard laparoscopic system was modified by placing a 480-nm short-pass excitation filter between the light cable and the laparoscope in addition to using a 2-mm-thick emission filter. A camera was used that allowed variable exposure time and gain setting. For mouse laparoscopy, a 3-mm 0° laparoscope was used. The mouse's abdomen was gently insufflated to 2 mm Hg via a 22-gauge angiocatheter. After laparoscopy, the animals were sacrificed, and the tumors were collected and processed for histologic review. The experiments were performed in triplicate., Results: Fluorescence laparoscopy enabled rapid imaging of the brightly fluorescent tumor in the pancreatic body. Use of the proper filters enabled simultaneous visualization of the tumor and the surrounding structures with minimal autofluorescence. Fluorescence laparoscopy thus allowed exact localization of the tumor, eliminating the need to switch back and forth between white and fluorescence lighting, under which the background usually is so darkened that it is difficult to maintain spatial orientation., Conclusion: The use of fluorescence laparoscopy permits the facile, real-time imaging and localization of tumors labeled with fluorescent proteins. The results described in this report should have important clinical potential.

Aim: Orthotopic models utilizing orthotopic implantation have been used for developing cancer models of multiple tumor entities. The aim of this study was to evaluate the role of orthotopic injection in establishing a model of esophageal cancer using a human green fluorescent protein (GFP) cell line of human esophageal carcinoma., Materials and Methods: Nude mice were orthotopically injected in the abdominal esophagus with stably transfected GFP-PT1590 cells. Tumor progression was examined by fluorescence imaging., Results: Fifty percent of animals developed extensive peritoneal spread without a distinct primary tumor at the injection site. Continuous and metastatic spread to the liver, lungs, and lymph nodes was also observed. Fluorescence imaging enabled fast and specific visualization of tumor progression without the need for anesthesia. Intraperitoneal and metastatic tumor spread of GFP-PT1590 esophageal carcinoma demonstrated a highly aggressive but heterogeneous behaviour. Although injection of the esophageal carcinoma cell line GFP-PT1590 did not lead to primary esophageal tumor development at the site of injection, 50% of the mice developed extensive peritoneal spread, as well as lymph node and organ metastasis., Conclusion: The orthotopic cell injection model resulted in peritoneal carcinomatosis of esophageal adenocarcinoma, which could be visualized in real time using fluorescence imaging.

A major goal for in vivo biology is to develop models which can express multiple colors of fluorescent proteins in order to image many processes simultaneously in real time. Towards this goal, the cyan fluorescent protein (CFP) nude mouse was developed by crossing non-transgenic nude mice with the transgenic CK/ECFP mouse in which the beta-actin promoter drives expression of CFP in almost all tissues. In crosses between nu/nu CFP male mice and nu/+ CFP female mice, approximately 50% of the embryos fluoresced blue. In the CFP nude mice, the pancreas and reproductive organs displayed the strongest fluorescent signals of all internal organs which vary in intensity. Orthotopic implantation of XPA-1 human pancreatic cancer cells expressing red fluorescent protein (RFP); or green fluorescent protein (GFP) in the nucleus and RFP in the cytoplasm, was performed in female nude CFP mice. Color-coded fluorescence imaging of these human pancreatic cancer cells implanted into the bright blue fluorescent pancreas of the CFP nude mouse afforded novel insight into the interaction of the pancreatic tumor and the normal pancreas, in particular the strong desmoplastic reaction of the tumor. The naturally enhanced blue fluorescence of the pancreas in the CFP mouse serves as an ideal background for color-coded imaging of the interaction of implanted cancer cells and the host. The CFP nude mouse will provide unique understanding of the critical interplay between the cancer cells and their microenvironment., (2009 Wiley-Liss, Inc.)

Context: The use of fluorescent proteins for in vivo imaging has opened many new areas of research. Among the important advances in the field have been the development of transgenic mice expressing various fluorescent proteins., Objective: To report whole-body and organ-specific fluorescence imaging to characterize the transgenic cyan fluorescent protein mouse., Design: Mice were imaged using two devices. Brightfield images were obtained with the OV100 Small Animal Imaging System (Olympus Corp., Tokyo, Japan). Fluorescence imaging was performed under the cyan fluorescent protein filter using the iBox Small Animal Imaging System (UVP, Upland, CA, USA)., Intervention: All animals were sacrificed immediately before imaging. They were imaged before and throughout multiple steps of a complete necropsy. Harvested organs were also imaged with both devices. Selected organs were then frozen and processed for histology, fluorescence microscopy, and H&E staining. Fluorescence microscopy was performed with an Olympus IMT-2 inverted fluorescence microscope., Main Outcome Measure: Determination of fluorescence intensity of different organs., Results: Surprisingly, we found that there is differential enhancement of fluorescence among organs; most notably, the pancreas stands out from the rest of the gastrointestinal tract, displaying the strongest fluorescence of all organs in the mouse. Fluorescence microscopy demonstrated that the cyan fluorescent protein fluorescence resided in the acinar cells of the pancreas and not the islet cells., Conclusions: The cyan fluorescent protein mouse should lead to a deeper understanding of pancreatic function and pathology, including cancer.

The role of host cells in tumor progression and metastasis is critical. Intrasplenic injection of tumor cells has long been known as an effective method of developing liver metastases in nude mice, whereas portal vein (PV) injection of tumor cells can result in rapid death of the tumor cells. Host cells were thought to play a role in these phenomena. We report here that after splenic injection of tumor cells, splenocytes cotraffic with the tumor cells to the liver and facilitate metastatic colony formation. Human colon cancer cells that express green fluorescent protein (GFP) linked to histone H2B in the nucleus and red fluorescent protein (RFP) in the cytoplasm (HCT-116-GFP-RFP) were injected in either the PV or spleen of nude mice and imaged at the subcellular level in vivo. Extensive clasmocytosis (destruction of the cytoplasm) of the cancer cells occurred within 6 hours after PV injection and essentially all the cancer cells died. In contrast, splenic injection of these tumor cells resulted in the aggressive formation of liver and distant metastasis. GFP spleen cells were found in the liver metastases that resulted from intrasplenic injection of the tumor cells in transgenic nude mice ubiquitously expressing GFP. When GFP spleen cells and the RFP cancer cells were coinjected in the PV, liver metastasis resulted that contained GFP spleen cells. These results suggest a novel tumor-host interaction that enables efficient formation of liver metastasis via intrasplenic injection.

As previously shown, the stem cell marker nestin is expressed in nascent blood vessels in transgenic nestin-driven green fluorescent protein (ND-GFP) nude mice. This mouse model was recently utilized to evaluate angiogenesis in primary tumors in an orthotopic model of pancreatic cancer. In the present study, nascent angiogenesis of pancreatic cancer liver metastasis in the ND-GFP transgenic nude mice after splenic injection of low-passage xPA-1 human pancreatic cancer cells expressing red fluorescent protein (RFP) was visualized by dual-color fluorescence imaging. ND-GFP was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing liver metastasis. Immunohistochemical staining showed that CD31 co-localized in ND-GFP-expressing nascent blood vessels. The density of nascent blood vessels in the tumor was readily quantitated. Gemcitabine significantly decreased the mean nascent blood vessel density in the pancreatic liver metastases. In conclusion, the dual-color model of the ND-GFP nude mouse with RFP-expressing pancreatic cancer liver metastases, enabled the simultaneous visualization and quantitation of nascent angiogenesis and its response to angiogenesis inhibitors. This model will be useful for understanding the mechanism of angiogenesis of pancreatic cancer liver metastasis and for the discovery of effective new inhibitors of this process.

We report here a novel transgenic nude mouse for the visualization of human tumor angiogenesis. We have recently shown that the neural stem cell marker nestin is expressed in hair follicle stem cells and blood vessel networks in the skin of C57/B6 transgenic mice with nestin regulatory element-driven green fluorescent protein (ND-GFP). Others have shown ND-GFP is expressed in the brain, pancreas, and testes in these mice. In the present study, the nestin ND-GFP gene was crossed into nude mice on the C57/B6 background to obtain ND-GFP nude mice. ND-GFP was expressed in the brain, spinal cord, pancreas, stomach, esophagus, heart, lung, blood vessels of glomeruli, blood vessels of skeletal muscle, testes, hair follicles, and blood vessel network in the skin of ND-GFP nude mice. Human lung cancer, pancreatic cancer, and colon cancer cell lines as well as a murine melanoma cell line and breast cancer tumor cell line expressing red fluorescent protein were implanted orthotopically, and a red fluorescent protein-expressing human fibrosarcoma was implanted s.c. in the ND-GFP nude mice. These tumors grew extensively in the ND-GFP mice. ND-GFP was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumors, visualized by dual-color fluorescence imaging. Results of immunohistochemical staining showed that CD31 was expressed in the ND-GFP-expressing nascent blood vessels. The ND-GFP transgenic nude mouse model enables the visualization of nascent angiogenesis in human and mouse tumor progression. These results suggest that this model is useful for the imaging of the angiogenesis of human as well as rodent tumors and visualization of the efficacy of angiogenetic inhibitors.

Precise fluorescence-guided surgery (FGS) for pancreatic cancer has the potential to greatly improve the outcome in this recalcitrant disease. To achieve this goal, we have used genetic reporters to color code cancer and stroma cells in a patient-derived orthotopic xenograft (PDOX) model. The telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 was used to label the cancer cells of a pancreatic cancer PDOX. The PDOX was previously grown in a red fluorescent protein (RFP) transgenic mouse that stably labeled the PDOX stroma cells bright red. The color-coded PDOX model enabled FGS to completely resect the pancreatic tumors including stroma. Dual-colored FGS significantly prevented local recurrence, which bright-light surgery or single-color FGS could not. FGS, with color-coded cancer and stroma cells has important potential for improving the outcome of recalcitrant-cancer surgery.