Evaluation of poly(d,l-lactide-co-glycolide) microspheres for the lung-targeting of yuanhuacine, a novel DNA topoisomerase I inhibitor

Abstract

The present study was intended to develop poly(d,l-lactide-co-glycolide) (PLGA; 50:50, 0.15 dL/g) microspheres (MS) loaded with yuanhuacine (YHC) for passive targeting in lung as well as providing a simple evaluation method for the targeting efficiency of MS. A kind of photochromic spiropyran dye was applied to label MS to clearly demonstrate the in vivo distribution characteristics through intravenous injection into mice and rabbits. Sections of 10-μm thickness from different organs were cut using a microtome, and fluorescent microscopy was used to determine the biodistribution of the MS. The average particle size of MS was 9.0 μm, and the glass transition temperature was 37–40°C. In vitro, the cumulative release achieved 50.8% in 24 h. Histological sections from different organs indicated that the amount of MS in lung achieved maximum in 6 h, as about 8 times as in liver and 70 times higher than the average concentration of other organs. In vivo, MS were gradually swelled and drug concentration remained just 10% in 12 h, which would not result in long time embolization in the lung. This evaluation method supplies a simple and visualized channel in focus for the targeting efficiency of PLGA MS.

Keywords::

• PLGA microspheres
• lung targeting
• yuanhuacine
• fluorescent spiropyran labeled
• anticancer

Acknowledgment

The authors wish to thank Renshu Zheng (Dalian Medical University, China) for his advice and assistance with histological analysis.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.