Background:Higher platelet levels are common in advanced tumor patients.It affects the progression and prognosis of cancer.Objectives:We attempted to identify the optimal method for establishing a murine model of lung metastatic melanoma with elevated platelets,and thus to provide a reasonable and stable simulative environment in vivo for investigating the role of platelets in the hematogenous metastasis of malignant melanoma.Methods:The platelet levels were elevated either through injection of platelets or the injection of murine recombinant thrombopoietin (TPO).Then,B16 F10 cells were injected in situ and via tail vein to develop an advanced melanoma model with elevated platelets.In the control group,mice were inoculated with B16 cells in the same manner as above.Following the tumor induction,dynamic recording captured the physiological and pathological indexes across the different groups.Upon completion of sampling,variations of indicators were compared.Results:The washed platelets and TPO were found to elevate platelets in mice (P<0.05).Compared to control group,elevated platelets(stimulated by TPO) promoted the formation of lung metastasis while inhibited the growth of subcutaneous tumor (P<0.05).The presence of tumor embolus and thrombus in the lungs may contribute to the decrease of platelets observed in the later stage.Multiple injections of platelets may lead to hyperactive peripheral immunity,probably related to infection and allogeneic infusion,which may exert some limitations on the research of tumor immune microenvironment.Conclusion:Endogenous platelet supplementation is more suitable for developing an advanced melanoma model with elevated platelets,effectively facilitating the exploration of tumor microenvironment in melanoma.