Biological systems are made up of very large numbers of different components interacting at various scales. Most genes, proteins and other cell components carry out their functions within a complex network of interactions and a single component can affect a wide range of other components. Interactions involved in biological processes have been first characterized individually but this "reductionist" approach suffers from a lack of information about time, space, and context in which the interactions occur in vivo. A global, integrative, approach has been developed for several years, focusing on the building of protein-protein interaction maps or interactomes. These interaction networks are complex systems, where new properties arise. They are part of the emergent field of systems biology, which focuses on studying complex biological systems such as a cell or organism, viewed as an integrated and interacting network of genes, proteins and biochemical reactions. Aging is associated with many diseases, such as cancer, diabetes, cardiovascular and neurodegenerative disorders and this limits the investigation of the mechanisms underlying the aging process when focusing on a single gene or a single biochemical pathway. The integration of existing intracellular interaction networks with the extracellular interaction network we have developed (MatrixDB, http://matrixdb.ibcp.fr ) will contribute to provide further insights into the global mechanisms of aging.