Affinity-Based Polymers Provide Long-Term Immunotherapeutic Drug Delivery Across Particle Size Ranges Optimal for Macrophage Targeting

Abstract

Long term drug delivery to specific arms of the immune system can be technically challenging to provide limited off-target toxicity as well as prolonged delivery and specific cellular targeting given the limits of current drug delivery systems. In this work, we demonstrate the robustness of a cyclodextrin (CD) polymer platform that can extend immunomodulatory drug delivery via affinity interactions to promote long-term, sustained release at multiple size scales. The parameter space of synthesis variables (pre-incubation and stirring speed) and post-synthesis grinding effects on resulting particle diameter were characterized. We demonstrate that polymerized CD forms exhibit size-independent release profiles of the small molecule drug lenalidomide (LND) and can provide similar drug delivery profiles as macro-scale CD polymer disks. CD polymer microparticles and nanoparticles demonstrated no significant cytotoxicity as compared to the base CD macromonomer when co-incubated with fibroblasts. Uptake of ground CD nanoparticles was significantly higher following incubation with RAW 264.7 macrophages in culture over originally synthesized, larger CD microparticles. Thus, the affinity/structure properties afforded by polymerized CD allow particle size to be modified to affect cellular uptake profiles independently of drug release rate for applications in cell-targeted drug delivery.

Polymer microparticles prolong delivery of the 15-PGDH inhibitor SW033291

“…To this end, we modulated parameters during polymerization - specifically temperature and mixing speed during polymerization - to generate smaller microparticles. We also explored manually crushing MPs with a mortar and pestle, which was previously reported to reduce particle diameters by 30% 17 . By reducing temperature and raising mixing speed to 1500 rpm, we generated MPs ∼40 um in diameter, a 50% reduction from the original protocol ( Figure 3 ).…”

“…Particle size was determined by a Nikon Eclipse TE300 inverted microscope (Nikon Inc., Tokyo, Japan) and analyzed for particle diameter in ImageJ. Previously studies have cited particle sizes of 81.88 ± 36.86 um with ‘Method A’ synthesis 17 .…”

“…Some particle groups were also crushed with a mortar and pestle for 2-3 minutes – referred to as ‘crushed’ - which is intended to reduce particle size after synthesis by ∼70-80 percent 17 .…”

“…Particle size was determined by a Nikon Eclipse TE300 inverted microscope (Nikon Inc., Tokyo, Japan) and analyzed for particle diameter in ImageJ. Previously studies have cited particle sizes of 81.88 ± 36.86 um with 'Method A' synthesis 17 . Some particle groups were also crushed with a mortar and pestle for 2-3 minutes -referred to as 'crushed' -which is intended to reduce particle size after synthesis by ~70-80 percent 17 .…”

“…Similar to previously established protocols for synthesizing β-CD microparticles (β-CD MPs), epichlorohydrin-crosslinked β-cyclodextrin prepolymer was solubilized in 0.2 M potassium hydroxide (25% w/v) and heated to 60 °C for 10 min 12,[16][17][18] . Light mineral oil was warmed in a beaker with a Tween85/Span85 solution (24%/76%) and stirred at 500 rpm.…”