Animal models of meningiomas.

Meningiomas are frequent intracranial and intraspinal tumors. They are tumors of the elderly, and meningioma growth at certain localizations, as well as recurrent tumors or primary aggressive biology may pose a therapeutic challenge. To understand the growth characteristics of meningiomas, animal models can provide insights both from a biological and therapeutical point of view. Using genetically-engineered mouse models (GEMM), it has been proven that alterations of the neurofibromatosis type 2 (NF2) gene are key steps for benign meningioma development. Aggressive meningiomas can be induced by simultaneous activation of Nf2 and the PDGF (platelet-derived growth factor)/-PDGF-Receptor (R) system, or inactivation of Tp53 and cdkn2ab in mice. However, mechanisms acting in NF2 wild-type meningiomas are poorly understood so far, because appropriate models are lacking. Xenograft models have been used either by implantation of primary cultures derived from human meningiomas, or immortalized human cell lines, respectively. While the value of primary cells is limited due to low rate of overall tumor growth and slow proliferation, xenograft approaches have been shown to be helpful for the evaluation of potential medical treatment options. Future studies must incorporate new molecular meningioma tumor drivers, as well as potential treatment options based on recurrent genetic alterations into the generation of meningioma models.