Chondroitin sulfate readily interacts with proteins in the extracellular matrix due to its negative charges. These interactions are important for regulating many cellular activities. The lecticans are a major part of the brain extracellular matrix, where the chondroitin sugar chains function to stabilize normal brain synapses as part of perineuronal nets. The levels of chondroitin sulfate proteoglycans are vastly increased after injury to the central nervous system where they act to prevent regeneration of damaged nerve endings. Although these functions are not as well characterized as those of heparan sulfate, new roles continue to be discovered for the chondroitin sulfate proteoglycans.