Peptides from milk protein hydrolysates to improve the growth of human keratinocytes in culture

Milk and colostrum are known to contain constituents having growth promoting activities on various human cell lines. Peptides from milk protein hydrolysates have also been shown to have various nutraceutical and biological properties. The aim of this research was to establish conditions for the in vitro hydrolysis of milk proteins and for the separation and identification of peptides that could promote growth of human skin cells in culture. Milk protein hydrolysates were obtained by using trypsin and chymotrypsin with various enzyme to substrate ratios (E/S) and degrees of hydrolysis (DH). Peptides contained in a 6% DH hydrolysate obtained with chymotrypsin were separated by size exclusion chromatography and supplemented in in vitro culture media to measure their efficacy to promote growth of keratinocytes isolated from human skin. The results indicated that growth promoting activity was increased up to 108% for keratinocytes cultured in medium supplemented with 300 mug mL(-1) of one peptide fraction. Fifteen peptides isolated from this fraction by RP-HPLC and characterized by Pico-Tag amino acids analysis were shown to have an average molecular weight of 800 Da and to contain high concentrations of hydrophobic and aromatic amino acids. (C) 2004 Elsevier Ltd. All rights reserved.