Biologically active human GM-CSF produced in the seeds of transgenic rice plants.

Rice flour is a well-known and characterized source of pharmaceutical ingredients, which are gluten-free and incorporated in many drug delivery applications such as excipient starch. To further exploit this uniqueness, the synthetic capacity of rice endosperm tissue, the basis of rice flour, was extended by genetic transformation. Recombinant human GM-CSF, a cytokine used in treating neutropenia and with other potential clinical applications, has been expressed in transgenic rice seeds using a rice glutelin promoter. Rice seeds accumulated human GM-CSF to a level of 1.3% of total soluble protein. The rice seed-produced human GM-CSF was found to be biologically active when tested using a human cell line TF-1. Use of rice as a host plant offers not only attractive features of safe production in seeds but also self-containment of foreign genes, as rice is primarily a self-pollinated crop plant.