Table 8.

Advantages and disadvantages of various models for meningiomas

Model	Description	Advantages	Disadvantages
Heterotopic xenograft	Implantation/xenografting of either cells or whole tumor pieces in a site other than intracranial/intraspinal
• Flank/subcutaneous	Implantation/xenografting of either cells or whole tumor pieces subcutaneously either via scalpel or injection. Matrigel can be utilized for a fixed position	Easy to implant, easy to measure and follow growth, inexpensive	Caliper measurements are estimates due to artefacts from skin and fatty tissue
• Subrenal	Surgically implantation of cells in the subrenal capsule. For technique see [127]	More accurate measurements compared to subcutaneous technique	Implantation and measurements require surgery and strain of the animals
Orthotopic xenograft	Implantation/xenografting of either cells or whole tumor pieces at dura attached areas intracranially and intraspinally
• Superficial	Implantation superficially most often through a burr hole in the frontal region	Easy to locate, low risk of bleeding perioperatively	Risk of cell reflux, if not careful
• Skull base	Implantation at the skull base most often through a burr hole in the frontal region	Fixed position, low risk of cell reflux	Depending on head angle of animals during implantation different placements on skull base Higher risk of bleeding
• Post-glenoid foramen	Natural cavity in rodents Located on the rostral area of the opening of the external acoustic meatus Different angles for different sites from cerebrum, cerebellum to brain stem and basal cistern [182]	Can be performed via subcutaneous injection, short procedure time, accessible to researchers without surgical skills [182]	Requires a sharp needle, increased risk of bleeding, handheld injection
Xenografted material
• The use of patient-derived primary material	Patient-derived samples obtained through surgery without immortalization. Benign tumors in particular are prone to senescence	Recapitulates each individual tumor more accurately to be used in personal targeted therapy	Varying TTRs between and within each patient derived tumor Mix of host DNA and human xenograft
• Using cell suspension	Injection of a suspension of cells	Easy to control number of cells used. Produces similar conditions for all animals in drug trials	Has to develop from cell suspension to tumor -Morphological changes can occur Only most viable cells survive culture
• Using whole tumor pieces	Implantation of whole tumor pieces from surgical specimens	Xenograft is morphologically representable to parent tumor	Difficult to make sure representable pieces of tumor is implanted and that it is consistent throughout animals
• The use of established/commercially available material	Immortalized patient-derived cells Often purchasable through biobanks or cell companies such as ATCC (American Type Culture Collection)	Near 100% tumor-take rate—need for a small number of animals Homogeneous tumors across all studies Can perform genomic alterations to cells to study differences [79]	Growth patterns do not represent primary meningiomas due to immortalization and homogenous cell population
• Syngeneic cell implantation	Use of cells deriving from the same species—in this setting murine meningioma to murine host	High tumor-take rate in immunocompetent animals	Assessment of mice derived tumors—Possible problems in translating to humans
Genetically Engineered Models	Knock-out or knock-in of genes through genetic manipulation (i.e. Cre-recombinase or RCAS/TVA)	Valuable tools for preclinical drug testing and for studying the underlying oncogenic drivers and molecular pathways in tumors	Expensive, labor intensive, other pathologies connected to genetic lesion
Corneal implantation	Implantation of tumor material in corneal pocket	Easy assessment of vessel growth through fundoscopy	Heterotopic model, loss of microenvironment