Vacuum inversion and securing of distal colonic pseudodiverticula with novel spiked O-rings

Diverticular disease is increasingly prevalent in Western societies and is associated with significant morbidity. OBJECTIVE: Two-stage endoscopic device development for inversion and secured ligation of colonic diverticula; first, human cadaver studies were performed to measure forces required for diverticular inversion; second, a novel set of devices (elastic spiked O-ring with delivery system) was tested in animals. DESIGN: Prospective, observational study of human cadavers and prospective, interventional study of a porcine model. SETTING: University hospital pathology laboratory and animal facility. INTERVENTION: Full-thickness inversion of the colonic wall with a pipelike delivery instrument to produce an inverted pseudodiverticulum that was secured with a spiked O-ring. MAIN OUTCOME MEASUREMENTS: The forces required for diverticular inversion, the secured closure of inverted pseudodiverticula, and the time until necrotic tissue falls off. RESULTS: A total of 248 of 248 of cadaveric sigmoid diverticula could be inverted by means of vacuum or forceps. The forces required for inversion ranged from 0.28 to 0.47 N (median, 0.37 N). Twenty-four spiked O-rings were delivered in 6 living pigs to produce 24 inverted pseudodiverticula. One animal died the day after the procedure of a pulmonary thromboembolism. In the remaining 5 pigs, all delivered spiked O-rings remained in place for 7 to 22 days. At necropsy, none of the inverted sites showed signs of perforation but rather full-thickness reparative scarring with ingrowth of connective tissue. LIMITATIONS: Animal model, stiff pipelike delivery instrument, variations in diverticular location, diameter, and size. CONCLUSIONS: Endoluminal inversion and securing of colonic diverticula induces tissue necrosis, diverticular sloughing, and full-thickness scarring

Imaging characteristics, tissue distribution, and spread of a novel oncolytic vaccinia virus carrying the human sodium iodide symporter.

INTRODUCTION: Oncolytic viruses show promise for treating cancer. However, to assess therapy and potential toxicity, a noninvasive imaging modality is needed. This study aims to determine the in vivo biodistribution, and imaging and timing characteristics of a vaccinia virus, GLV-1h153, encoding the human sodium iodide symporter (hNIS. METHODS: GLV-1h153 was modified from GLV-1h68 to encode the hNIS gene. Timing of cellular uptake of radioiodide (131)I in human pancreatic carcinoma cells PANC-1 was assessed using radiouptake assays. Viral biodistribution was determined in nude mice bearing PANC-1 xenografts, and infection in tumors confirmed histologically and optically via Green Fluorescent Protein (GFP) and bioluminescence. Timing characteristics of enhanced radiouptake in xenografts were assessed via (124)I-positron emission tomography (PET). Detection of systemic administration of virus was investigated with both (124)I-PET and 99m-technecium gamma-scintigraphy. RESULTS: GLV-1h153 successfully facilitated time-dependent intracellular uptake of (131)I in PANC-1 cells with a maximum uptake at 24 hours postinfection (P<0.05). In vivo, biodistribution profiles revealed persistence of virus in tumors 5 weeks postinjection at 10(9) plaque-forming unit (PFU)/gm tissue, with the virus mainly cleared from all other major organs. Tumor infection by GLV-1h153 was confirmed via optical imaging and histology. GLV-1h153 facilitated imaging virus replication in tumors via PET even at 8 hours post radiotracer injection, with a mean %ID/gm of 3.82 ± 0.46 (P<0.05) 2 days after intratumoral administration of virus, confirmed via tissue radiouptake assays. One week post systemic administration, GLV-1h153-infected tumors were detected via (124)I-PET and 99m-technecium-scintigraphy. CONCLUSION: GLV-1h153 is a promising oncolytic agent against pancreatic cancer with a promising biosafety profile. GLV-1h153 facilitated time-dependent hNIS-specific radiouptake in pancreatic cancer cells, facilitating detection by PET with both intratumoral and systemic administration. Therefore, GLV-1h153 is a promising candidate for the noninvasive imaging of virotherapy and warrants further study into longterm monitoring of virotherapy and potential radiocombination therapies with this treatment and imaging modality

PET-detection of timing characteristics of GLV-1h153-facilitated radiouptake by intratumorally-treated PANC-1 xenografts.

<p>A. Two ×10⁷ PFU of GLV-1h153,was injected ITly into PANC-1 hindleg tumor-bearing mice (3 mice). ¹²⁴I PET scanning was obtained 48 hours after infection and 1 hour after radiotracer administration. GLV-1h153-infected PANC-1 tumors were easily visualized (shown with arrows). Stomach and thyroid were also visualized due to native NIS expression, and the bladder due to tracer excretion. Gray scale reflects maximum and minimum radiouptake within the tumor regions on PET images, with greater black intensity signifying greater radiouptake. B. Although absolute radiouptake decreased between 1 and 8 hrs after radiotracer administration, ratio of uptake versus background steadily increased. C. Enhanced radiouptake in tumors infected with GLV-1h153 compared to GLV-1h68 and PBS 8 hrs after radiotracer injection was confirmed via tissue radiouptake assays and correlated with quantitative PET (2–3 mice per group). Enhanced uptake in the stomach is evident in all groups due to native NIS expression. d. Tumor infection with GLV-1h153 was confirmed with GFP and CT-PET in the same mice 2 days post intratumoral injection.</p

PET imaging and γ-scintigraphy of GLV-1h153 replication in intravenously treated PANC-1 xenografts.

<p>Three groups of 2 animals each, bearing subcutaneous PANC-1 xenografts on the right hindleg, were injected IVly (2 mice) or ITly (2 mice) with 2×107 PFU of GLV-1h153, or PBS (2 mice). One mouse from each group was imaged with ¹²⁴I-mediated PET scanning and the other imaged with ^99mTcO₄-mediated γ-scintigraphy. GLV-1h153 replication in both ITly- and IVly-treated PANC-1 tumors were easily visualized with both modalities (shown with arrows). Stomach and thyroid were also visualized due to native NIS expression, and the bladder due to tracer excretion. Gray scale reflects maximum and minimum radiouptake within the tumor regions by each modality, with greater black intensity signifying greater radiouptake.</p

GLV-1h153 construct.

<p>GLV-1h153 was derived from GLV-1h68 by replacing the <i>gusA</i> expression cassette at the <i>A56R</i> locus with the <i>hNIS</i> expression cassette through homologous recombination. Both viruses contain RUC-GFP and <i>lacZ</i> expression cassettes at the <i>F14.5L</i> and <i>J2R</i> loci, respectively. PE, PE/L, P11, and P7.5 are VACV synthetic early, synthetic early/late, 11K, and 7.5K promoters, respectively. TFR is human transferrin receptor inserted in the reverse orientation with respect to the promoter PE/L.</p

Optical and histologic detection of viral replication using vaccinia marker genes.

<p>A. Presence of GLV-1h153 in tumors was detected histologically, shown here with the IT group 2 days post virus injection. Areas staining positive with antibodies against GFP and VACV antigen A27L corresponded and were easily visualized in GLV-1h153-injected tumors, whereas no staining was evident in untreated tumors. Areas of A27L staining is also shown at 400× magnification. B. GFP expression was optically monitored, shown here 5 weeks postinjection. Control tumors were larger than GLV-1h153-treated tumors, both when administered intratumorally or intravenously. GLV-1h153 was also detected via bioluminescence imaging 2 weeks posttreatment.</p