ABSTRACT
In the development of cell-penetrating peptides (CPPs) for medical use, the same
issues as for any other new drug have to be addressed: efficacy, safety, production
issues, and medical need. In this regard, the choice of CPPs as a therapeutic platform
appears a very good one. In fact, very central natural biological processes, such as
the mammalian immune system or other defense systems in various organisms, are
based on natural CPPs which help to protect and/or cure the host from diseases; for
example, by eliminating invading microorganisms or infected host cells. CPPs play
a role both in eukaryotic and prokaryotic systems and viruses, and evolution has
optimized CPPs for various purposes. On the one hand, they can be potent killing
agents and, on the other, nontoxic cytosolic delivery agents.
