Patent ID: 7718851

Claim:
A method for making a cell culture medium comprising the steps of: (a) obtaining a monocot plant stably transformed with a chimeric gene having (i) a seed maturation-specific promoter, (ii) operably linked to said promoter, a leader DNA sequence encoding a monocot seed-specific transit sequence capable of targeting a linked polypeptide to an endosperm-cell organelle, wherein the promoter operably linked to the leader sequence comprises either SEQ ID NO:13 or SEQ ID NO:14 and (iii) a protein-coding sequence encoding a protein normally present in human milk and having growth factor activity, (b) cultivating the transformed plant under seed-maturation conditions, (c) harvesting the seeds from the cultivated plant, (d) extracting the harvested seeds with an aqueous solution, thereby obtaining an extract of water soluble plant components comprising at least 3% by total protein weight of the milk protein, (e) purifying the milk protein from the aqueous solution, and (f) adding the purified milk protein to cell culture medium.