Intracytoplasmic delivery of anionic proteins.

Protein delivery is emerging as an interesting alternative to gene delivery. We have used our experience with transfection to develop a technique for efficient delivery of anionic proteins such as antibodies into the cytoplasm of cells. As for DNA, when complexed with cationic lipids, large amounts of proteins are shown to enter adherent cells via ubiquitously expressed syndecans. However, protein surface area rather than electric charge ratio governs the delivery characteristics. Delivery of anti-beta-actin and anti-alpha-tubulin IgG's leads to fiber depolymerization. Intracellular delivery of an antibody could thus be regarded as another method for interfering with gene activity.