Due to the potential risk of disease contamination of human serum albumin (HSA) derived from fractionation of pooled donor blood and the increasing demand of HSA in therapeutic applications, production of recombinant human serum albumin (rHSA) has become attractive as an alternative to blood-derived HSA. While significant progress has been made in various protein expression systems, particularly in yeast, the cost of rHSA production is very high. Due to a large capital requirement, the scale of rHSA production is limited and will not be able to meet the market demand. Ventria Bioscience has developed a proprietary protein expression system, ExpressTec, and has recently used it to express rHSA in rice grain with an expression level of 8 gram/kg flour weight (40% total soluble protein) which is 4 to 100 folds higher than other expression systems. Rice grain can be produced at cost of less than <0.22 /kg thus rHSA derived from rice can be produced at <$0.04/gram as raw material. This low cost alternative to rHSA can be scaled up easily. In this phase I SBIR proposal, we plan to develop a homozygous line and characterize the transgenic plants. At the same time, we will develop rHSA purification procedure and prepare rHSA from rice grain. Then we will conduct in vitro protein analysis to compare biochemical and biophysical characteristics between rHSA and native HSA. In phase II, we will produce a large amount of rice grain and purify sufficient quantity of rHSA for both preclinical and clinical trials with both model animals and human subjects. Our long term goal is to produce large quantities and high quality of rHSA at cost comparable to blood derived HSA for therapeutic applications. ? ?