Cell-penetrating peptides

The established view in cellular biology dictates that the cellular interna lization of hydrophilic macromolecules can only be achieved through the cla ssical endocytosis pathway. However, in the past five years several peptide s have been demonstrated to translocate across the plasma membrane of eukar yotic cells by a seemingly energy-independent pathway. These peptides have been used successfully for the intracellular delivery of macromolecules wit h molecular weights several times greater than their own. Cellular delivery using these cell-penetrating peptides offers several advantages over conve ntional techniques because it is efficient for a range of cell types, can b e applied to cells en masse and has a potential therapeutic application.