Vasoactive Intestinal Peptide Amphiphile Micelle Material Properties Influence Their Cell Association and Internalization
Vasoactive intestinal peptide (VIP) is a promising anti-inflammatory peptide therapeutic that is known to induce biological effects by interacting with its cognate receptor (i.e., VPAC) on the surface of antigen presenting cells (APCs). For VIP-based drug delivery technologies like nano- and microparticles, little is known about the effect VPAC targeting has on APC behavior. This is further influenced by the fact that particulate material properties including chemistry, shape, and size are all known to influence APC behavior. In this study, peptide amphiphile micelles (PAMs) were employed as a modifiable platform to study the impact VPAC targeting and physical particle properties have on their association with macrophages. VIP amphiphile micelles (VIPAMs) and their scrambled peptide amphiphile micelle analogs (SVIPAMs) were fabricated from various chemistries yielding particle batches that were comprised of spheres (10 - 20 nm in diameter) and/or cylinders of varying lengths (i.e., 20 - 9000 nm). Micelle surface attachment to and internalization by macrophages were observed using confocal microscopy and their association was characterized by flow cytometry. The enclosed work provides strong evidence that macrophages rapidly bind VPAC specific micelles independent of physical properties though micelle shape and size as well as receptor-specificity all influence their long-term macrophage association. Specifically, a mixture of spherical and short cylindrical VIPAMs were able to achieve the greatest cell association which may correlate to their capacity to fully bind the VPAC receptors available on the surface of macrophages. These results provide the foundation of how nano- and microparticle physical properties and targeting capacity synergistically influence their capacity to associate with APCs.