Translational pancreatic cancer research: A comparative study on patient-derived xenograft models.

AIM: To assess the viability of orthotopic and heterotopic patient-derived pancreatic cancer xenografts implanted into nude mice. METHODS: This study presents a prospective experimental analytical follow-up of the development of tumours in mice upon implantation of human pancreatic adenocarcinoma samples. Specimens were obtained surgically from patients with a pathological diagnosis of pancreatic adenocarcinoma. Tumour samples from pancreatic cancer patients were transplanted into nude mice in three different locations (intraperitoneal, subcutaneous and pancreatic). Histological analysis (haematoxylin-eosin and Masson's trichrome staining) and immunohistochemical assessment of apoptosis (TUNEL), proliferation (Ki-67), angiogenesis (CD31) and fibrogenesis (α-SMA) were performed. When a tumour xenograft reached the target size, it was re-implanted in a new nude mouse. Three sequential tumour xenograft generations were generated (F1, F2 and F3). RESULTS: The overall tumour engraftment rate was 61.1%. The subcutaneous model was most effective in terms of tissue growth (69.9%), followed by intraperitoneal (57.6%) and pancreatic (55%) models. Tumour development was faster in the subcutaneous model (17.7 ± 2.6 wk) compared with the pancreatic (23.1 ± 2.3 wk) and intraperitoneal (25.0 ± 2.7 wk) models (P = 0.064). There was a progressive increase in the tumour engraftment rate over successive generations for all three models (F1 28.1% vs F2 71.4% vs F3 80.9%, P < 0.001). There were no significant differences in tumour xenograft differentiation and cell proliferation between human samples and the three experimental models among the sequential generations of tumour xenografts. However, a progressive decrease in fibrosis, fibrogenesis, tumour vascularisation and apoptosis was observed in the three experimental models compared with the human samples. All three pancreatic patient-derived xenograft models presented similar histological and immunohistochemical characteristics. CONCLUSION: In our experience, the faster development and greatest number of viable xenografts could make the subcutaneous model the best option for experimentation in pancreatic cancer.

The use of TachoSil as sealant in an experimental model of colonic perforation.

BACKGROUND: The suture dehiscence has traditionally represented a major surgical problem that has not fully resolved. Surgeons should perform sutures in nonoptimal conditions using different methods of sealing and/or reinforcement of suture. The aim is to assess the effectiveness of TachoSil in an experimental model of colon perforations in a simulated precarious situation. METHODS: Forty Wistar rats of both genders (14-24 weeks old) were equally divided in 2 groups; study group was submitted to extended starvation and segmental ischemia. The surgical complications analyzed were animal death, colonic leaks, or intra-abdominal infection, either as local abscesses or diffuse peritonitis. The burst pressure was measured in millimeters of mercury. The histological analysis was performed according to Ehrlich and Hunt numerical scale modified by Phillips. RESULTS: Only 1 animal belonging to the study group died as a consequence of the colonic ischemia. The eventual colonic leak or diffuse peritonitis was reported. Three local abscesses were observed in the study group and one in the control group, and numerous microscopic abscesses in histological analysis (12 vs. 11) were detected. The average burst pressure in the study group was 209.47 ± 50.274 versus 203 ± 51.514 mm Hg in the control group. No differences were observed in any of the variables analyzed in the histological activity. CONCLUSION: TachoSil has proven useful as a sealant of colonic perforations in our experimental study. We therefore conclude that its use in situations of insecurity may be adequate, even in optimal conditions in which reinforcement of previous suture is not strictly required.

Tumour necrosis factor-alpha and nitric oxide mediate apoptosis by D-galactosamine in a primary culture of rat hepatocytes: exacerbation of cell death by cocultured Kupffer cells.

BACKGROUND: Prostaglandin E1 (PGE1) reduces cell death in experimental and clinical liver dysfunction. OBJECTIVES: Whether PGE1 protects against D-galactosamine (D-GalN)-associated hepatocyte cell death by the regulation of tumour necrosis factor-alpha (TNF-alpha) and/or nitric oxide (NO) in hepatocytes or cocultured Kupffer cells was examined. METHODS: Anti-TNF-alpha antibodies were used to evaluate the role of TNF-alpha during D-GalN cytotoxicity and its protection by PGE1 in cocultured hepatocytes and Kupffer cells. Cell apoptosis and necrosis were assessed by DNA fragmentation and lactate dehydrogenase release, respectively. Nitrite+nitrate (NOx), as NO end products, and TNF-alpha concentrations were measured in the culture medium. The role of NO was determined by measuring inducible NO synthase (iNOS) expression and the effect of its inhibition during d-GalN cytotoxicity and its protection by PGE1. RESULTS: D-GalN enhanced hepatocyte cell death associated with high TNF-alpha and NOx levels in a culture medium. Anti-TNF-alpha and iNOS inhibition suggested that TNF-alpha was mediating apoptosis, but not necrosis, through the stimulation of NO production. The antiapoptotic activity of PGE1 was associated with a reduction of NO production, but was blocked by iNOS inhibition. This apparent contradiction was explained by the ability of PGE1 to enhance iNOS expression shortly after its administration and inhibit it later during d-GalN treatment. Anti-TNF-alpha antibodies did not reduce the exacerbation of d-GalN-associated cell death in hepatocytes by cocultured Kupffer cells. CONCLUSION: TNF-alpha mediates D-GalN-induced apoptosis via NO production in cultured hepatocytes. The protective effect of PGE1 against D-GalN-induced apoptosis is probably through the induction of low iNOS expression that was followed by a reduction of iNOS expression and NO production induced by the hepatotoxin. The exacerbation of hepatocyte cell death by Kupffer cells was not related to TNF-alpha and NO.