In biology, fractones are structures consisting primarily of laminin and heparan sulfate proteoglycan (HSPG) first discovered in the extracellular matrix niche of the subventricular zone of the lateral ventricle (SVZa) in the mouse brain.

Fractones were discovered in 2002 in the extracellular matrix niche of the subventricular zone of the lateral ventricule (SVZa) in a mouse brain.

[1] Originally found in the neurogenic areas of the brain, recent studies indicate that fractones are also present in multiple organisms, including but not limited to plants, fungi, invertebrates, and vertebrate animals.

The HSPG part of fractones is responsible for growth factor binding, retention and release in the extracellular matrix.

These proteoglycans bind growth factor in the extracellular matrix to regulate stem cell proliferation, which has been demonstrated in the adult brain neurogenic zone, where fractones are responsible for the production and differenciation of new neurons.