Assessment of the Physical Properties, Drug Loadability and Release Profile, and Biocompatibility of UniPearls® Microspheres

Microspheres based transarterial chemoembolization is important for liver cancer treatment. UniPearls^® is a novel product of microspheres featuring a uniform particle size and independently developed in China. This study aimed to investigate the physical properties, drug loading and releasing ability, and biocompatibility of UniPearls^®. Various experiments were performed including: compression rupture, suspendability, simulated use, drug loading, drug releasing, cytotoxicity, mouse lymphoma assay (MLA), muscle implant, intradermal reaction, guinea pig maximization test (GPMT), and systemic toxicity. UniPearls^® or UniPearls^® extraction liquid was set as experimental group(s), while HepaSphere^® or related extraction liquid was set as control group(s). UniPearls^® showed no microsphere rupture after compression to 1 μm for 10 or 20 min, but some ruptures for 30 min, and microspheres were successfully suspended in a short time. In a 3-dimensional (3D) hepatic artery model, UniPearls^® exhibited no microsphere break, delivery block, shape change or unexpected catheter outflow during simulated experiment. The maximum loading rates of 40-100 mg doxorubicin and irinotecan were 100% and 97.4% by UniPearls^®, respectively; then the releasing rates at plateaus with different-dose doxorubicin and irinotecan ranged 34.0%-46.5% and 85.6%-91.8%, respectively. In vitro experiments revealed no cytotoxicity or impact on inducing gene mutation by UniPearls^®. In vivo experiments disclosed no local reaction, skin sensitization, obvious acute/subchronic systemic toxicity symptoms by UniPearls^®. Besides, the above indexes were not different between UniPearls^® and controls (HepaSphere^® or related extraction liquids). UniPearls^® serves as a good product of microspheres, benefiting from its satisfied physical properties, drug loadability, releasing ability and biocompatibility.