In the central nervous system, nerve cells adhere to the extracellular matrix. Type I collagen is the major class of insoluble fibrous proteins in the extracellular matrix. A previous study has shown that neural stem and progenitor cells, cultured on collagen matrices, are able to expand actively and generate neurons. Collagens can be classified into hydrolyzed and non-hydrolyzed collagens, or two-dimensional and three-dimensional collagens. Which form of collagen is suitable for nerve cell culture? Dr. Mohsen Fathi Najafi and colleagues from Mashhad University of Medical Science, Iran, investigated the effects of hydrolyzed and non-hydrolyzed collagen and two-dimensional and three-dimensional collagen matrices on cell survival, attachment and neurite outgrowth of primary cultured nerve cells using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide co-lorimetric assay and inverted microscopy. Hydrolyzed collagen facilitated nerve cell survival and neurite outgrowth, but it had no obvious influences on cell attachment. In contrast, non-hydrolyzed two-dimensional collagen matrix had no obvious effects on neurite outgrowth. These findings, published the Neural Regeneration Research (Vol. 8, No. 23, 2013), suggest that hydrolyzed collagen is an ideal nerve cell culture media.