The effects of low molecular weight materials derived from animal tissues on the growth of animal cells in vitro

A low molecular weight fraction was isolated by gel filtration from commercially prepared tissue hydrolysates. These low molecular weight materials could replace the serum supplement for the growth of some established cell lines in vitro , and they enabled the cultured cells to grow at a rate comparable to that observed with the serum supplement. It would appear that the active material is a mixture of products, possibly peptide in nature, with molecular weight between 700 to 1600. A high molecular weight fraction separated from these hydrolysates did not stimulate the growth of the cells to the same extent and, under some conditions, caused the cells to clump.