Kirston E. Koths

Structure-function studies on human macrophage colony-stimulating factor (M-CSF)

M‐CSF (CSF‐1) can be produced in a variety of structural forms that may affect function in vivo. Truncated, nonglycosylated forms of recombinant M‐CSF (rM‐CSF) from E. coli have been refolded in vitro in high yield and shown to be functionally equivalent in vitro to glycosylated rM‐CSF secreted from mammalian cells. An N‐terminal domain of 149 amino acids is produced by all of the known M‐CSF mRNA splice variants and is the region responsible for bioactivity observed in vitro. Heterodimeric rM‐CSFs from different splice variants containing this domain were produced in pure form by refolding in vitro, and are fully active, but have yet to be observed in vivo. The circulating half‐life of truncated M‐CSF forms injected intravenously into rats increased with the MW of the M‐CSF used. Large increases in half‐life in vivo were observed following chemical addition of a single molecule of 10 kD polyethylene glycol to rM‐CSF in vitro.

Recombinant proteins for medical use: the attractions and challenges

Recombinant proteins that have survived the challenges of process development and clinical trials are becoming blockbuster medical products. Growth factors, enzymes and antibodies are being improved by mutational approaches, fused with other proteins, and even chemically modified in vitro. Drug development and testing approaches have advanced, and proteins produced in transgenic animals are new becoming available. Future protein products might include cancer vaccines and therapies for a variety of genetic diseases, but alternative treatments involving gene therapy or small synthetic compounds will provide competition.