Standardization of A375 human melanoma models on chicken embryo chorioallantoic membrane and Balb/c nude mice

Cutaneous melanoma is a metastatic disease characterized by high resistance to treatment, the incidence of which has alarmingly increased worldwide over the past years. A thorough characterization of tumor onset, progression and metastasis is compulsory to overcome the gaps existent in melanoma biology. The present study suggests a well‑established protocol and a detailed histological description of human melanoma models in ovo and in vivo obtained by the inoculation of A375 cells to chick embryo chorioallantoic membrane (CAM) and Balb/c nude mice. The inoculation of A375 cells on CAM led to the formation of compact primary and secondary tumors on day 4 post‑inoculation, with mean surface area values of 2.2±0.4 mm2 and 1.5±0.3 mm2, respectively. Moreover, the vessels around the tumors presented a spike wheel pattern, indicating a strong angiogenic reaction. All the injected mice, apart from one, developed solid polypoid primary tumors with lobulated surfaces and intense vascularization, and achromic epithelioid malignant melanocytes with vesiculous nuclei and necrosis area were detected. Metastasis was histologically confirmed in only 30% of the mice with the tumor xenografts. These data indicate that the standardization protocols proposed are complex and reproducible, and can be further employed for the therapeutic surveillance of antiangiogenic and anticancer agents.