Improving In Vivo Retention of Bioscavengers In Blood

Abstract

We are developing technologies to increase the in vivo retention times of bioscavengers by attaching them to red blood cells (RBCs) using cell‐penetrating peptides (CPPs). CPPs are short peptides of 5‐40 amino acids, with the ability to translocate inside the cells by different mechanisms including direct physical transfer through the lipid bilayer. CPPs can either anchor the bioscavnegers to the cell surface, or internalize them by associated transport. Our results show that conjugation of the bioscavenger butyrylcholinesterase (BChE) to CPPs differently affected the enzymatic activity. Conjugation of Buforin I impaired the BChE activity by 50%. In contrast, the HIV Tat‐protein transduction domain (Tat) reduced the BChE activity by 11% in comparison to the unconjugated BChE. Tat was also found to significantly increase the association of BChE activity to RBC. Association of Tat to RBCs was also monitored by confocal microscopy using fluorescent microspheres. In addition, we are using artificial liposomes mimicking the RBC membrane composition as a further way to test CPP association to biological membranes. We are also investigating the capability of other RBC‐interacting peptides to associate bioscavengers. We expect that such technologies increase the effectiveness of protein therapeutics, or prophylactics, in blood borne treatments.Supported by DTRA#1.D0011_08_WR_C.