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.

Post-transplant lymphoproliferative disease in liver transplant recipients

INTRODUCTION

Post-transplant lymphoproliferative syndrome (PTLD) is a rare and potentially life-threatening complication after liver transplantation. The aim of this study was to analyze the clinicopathologic features related to PTLD in a single institution after liver transplantation.

METHODS

Observational study where we have retrospectively analyzed 851 cases who underwent liver transplantation. Ten cases have developed PTLD. Their clinical-pathological characteristics and the treatment received have been analyzed.

RESULTS

PTLD incidence was 1.2% (10/851). The mean time from liver transplantation to PTLD diagnosis was 36 months (range 1.2 to 144 months). PTLD localization was extranodal in all cases, the most frequent location being intestinal. Seven cases showed a monomorphic lymphoma which in all cases was differentiated B cell lymphomas. Fifty per cent of the series were seropositive for Epstein-Barr virus. Five patients were alive at the time of the review. Among these patients, we observed three cases of complete remission and two cases of disease stabilization. The death rate was higher in the first year after diagnosis of PTLD.

CONCLUSION

PTLD is a rare complication after liver transplantation, but it may pose a threat to the life of a liver transplant recipient. It is essential to identify patients at risk, to establish an early diagnosis and treatment that can change the outcome of the disease.