Peptides which enhance transport across tissues and methods of identifying and using the same

DETAILED DESCRIPTION The invention provides a method of identifying a peptide which permits or facilitates the transport of an active agent through a human or animal tissue.
A predetermined amount of phage from a random phage library is plated unto or brought into contact with a first side, preferably the apical side, of a tissue sample, either in vitro, in vivo or in situ, or polarized tissue cell culture.
At a predetermined time, the phage which is transported to a second side of the tissue opposite the first side, preferably the basolateral side, is harvested to select transported phages.
The transported phages are amplified in a host and this cycle of events is repeated (using the transported phages produced in the most recent cycle) a predetermined number of times, such as from zero to six times, to obtain a selected phage library containing phage which can be transported from the first side to the second side.
Lastly, the sequence of at least one random peptide coded by phage in the selected phage library is determined in order to identify a peptide which permits or facilitates the transport of an active agent through a human or animal tissue.
The transported phage can be viewed as a combination of a transporter peptide (the at least one random peptide coded by the phage) associated with an active agent payload (the phage) in which the transporter peptide facilitates the transport of the active agent through the tissue.
Thus, the random peptides coded by phage in the selected phage library are predictively capable of facilitating transport of other active agents, such as drug encapsulated nano- and/or microparticles, through the particular tissue.
Preferably, the tissue sample derives from the duodenum, jejunum, ileum, ascending colon, transverse colon, descending colon, pelvic colon, vascular endothelium cells which line the vascular system, vascular endothelial cells which form the blood brain barrier, alveolar cells, liver, kidney, bone marrow, retinal cells of the eye or neuronal tissue