Design of Functionalized Targeted Liposomes for Therapeutic Delivery and Imaging

Linda Columbus
Department of Chemistry, College of Arts & Sciences, UVa
Alison Criss
Microbiology Department, School of Medicine, UVa

Pathogenic microorganisms with major impacts on human health hijack normal cellular pathways by mimicking or manipulating host machinery. One mechanism by which pathogenic bacteria exert their effects is through surface presentation of membrane proteins that aberrantly engage host receptors. We postulate that these bacterial membrane proteins can be exploited to create novel nanoscale drug delivery systems that will overcome current limitations to nanoparticle design and function. Liposomes are closed spherical vesicles ranging in size from 200 nm to 2.5 μm. The vesicles consist of a lipid bilayer that encapsulates an aqueous phase. To date, there are several liposomal nanoscale drug delivery systems on the market (e.g. Doxil® cancer therapeutic for AIDS-related Kaposi’s sarcoma). We propose to design drug containing-liposomes that are functionalized with Neisseria Opa proteins, which induce cellular engulfment by binding to distinct families of host receptors. Since the host receptors are expressed on different cell and tissue types, Opa-receptor interactions should be able to target cargo in a high-affinity manner. Two Opa proteins have been expressed in E. coli, purified, and refolded into liposomes, and we have shown that the refolded Opa proteins retain specificity for cognate receptors and functionality in vivo. We hypothesize that the different adhesive properties of each Opa protein will confer unique abilities on liposomes to deliver cargo to targeted host cells. We propose to prepare an array of liposomes, each carrying an Opa protein that conveys a different receptor specificity, and characterize the properties of the Opa+ liposomes for their cellular invasion and subcellular localization. The proposal requires a multidisciplinary approach - biophysics for the preparation of the Opa+ liposomes, and cellular microbiology to determine the consequences of Opa+ liposome delivery relative to our knowledge of Neisseria – host interactions. The PIs of the proposal have demonstrated expertise in these areas and have initiated a strong collaboration, resulting in preliminary results supporting the feasibility of the project. We anticipate the results of our study will establish a new paradigm for receptor-mediated nanoparticle targeting, with far-reaching implications for directed chemotherapy, focused drug delivery, and noninvasive whole-body imaging.