Orthotopic animal model of pseudomyxoma peritonei: An in vivo model to test anti-angiogenic drug effects.

Pseudomyxoma peritonei (PMP) is an uncommon peritoneal mucinous carcinomatosis confined to the peritoneal cavity. The rarity of PMP in humans makes evaluation of the disease biological features and new therapeutic strategies difficult. Accordingly, there is a need for animal models of PMP. Human PMP tissue was i.p. grafted and grown into nude mice, then constituted into reliable and reproducible orthotopic models. Histological and immunostaining analysis was performed. Bevacizumab was injected twice a week either during tumor growth or after cytoreductive surgery. In vivo imaging of tumor angiogenesis was performed using barium sulfate or isolectin microangiography and Doppler ultrasonography of the superior mesenteric artery. Tumor angiogenesis was confirmed by the presence of tortuous vascular networks with high levels of expression of CD31, vascular endothelial cadherin, and desmin. Doppler ultrasonography of the superior mesenteric artery revealed a twofold increase in blood flow velocity compared with tumor-free mice (P < 0.001). Bevacizumab administration was correlated with the normalization of tumor vascularity when injected during tumor growth and with the stabilization of the histological and hemodynamic findings when injected after cytoreductive surgery. Our PMP models mimic human PMP. Our results confirmed the presence of tumor angiogenesis related to PMP growth. Our murine model allows researchers to actually bench test and evaluate, in preclinical studies, the efficacy of new therapeutic strategies and anti-angiogenic therapies.