Principles of gene-, cell-, and tissue engineering-based approaches for meniscal repair. Schematic view of a bucket-handle meniscal tear. Gene-, cell-, and tissue engineering-based approaches for meniscal repair include the direct in vivo administration of a (viral) gene transfer vector or of ex vivo genetically modified cells within a meniscal lesion, and the implantation of biocompatible and bioactive materials in the form of scaffolds that deliver either a recombinant factor, gene transfer vector, or ex vivo genetically modified cells that may serve the dual role of providing the therapeutic factor and repopulating the lesion.