Multicompartmental, multilayered probucol microcapsules for diabetes mellitus: Formulation characterization and effects on production of insulin and inflammation in a pancreatic β-cell line

Abstract

Context

We have shown that the primary bile acid, cholic acid (CA), has anti-diabetic effects in vivo. Probucol (PB) is a lipophilic drug with potential applications in type 2 diabetes (T2D).

Objective

This study aimed to encapsulate CA with PB and examine the formulation and surface characteristics of the microcapsules. We also tested the microcapsules’ biological effects on pancreatic β-cells.

Methods

Using the polymer, sodium alginate (SA), two formulations were prepared: PB-SA (control), and PB-CA-SA (test). Complete characterizations of the morphology, shape, size, chemical, thermal, and rheological properties, swelling and mechanical strength, cross-sectional imaging (Micro CT), stability, Zeta-potential, drug contents, and PB release profile were carried out, at different temperature and pH values. The microcapsules were applied to a NIT-1 cell culture and the supernatant was analyzed for insulin and TNF-α concentrations.

Results

CA incorporation optimized the PB microcapsules, which exhibited pseudoplastic–thixotropic rheological characteristics. The size of the microcapsules remained similar after CA addition, and the microcapsules showed even drug distribution and no chemical alterations of the excipients. Micro-CT imaging, differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy showed consistent microcapsules with uniform shape and morphology. PB-CA-SA microcapsules enhanced NIT-1 cell viability under hyperglycemic states and resulted in improved insulin release as well as reduced cytokine production at the physiological glucose levels.

Conclusions

The addition of the primary bile acid, CA, improved the physical properties of the microcapsules and enhanced their pharmacological activity in vitro, suggesting potential applications in diabetes treatment.

Keywords::

• artificial-cell microencapsulation
• bile acids
• probucol
• NIT-1 β-cells
• diabetes mellitus
• inflammation

Acknowledgments

The authors acknowledge the Australian Postgraduate Award (APA) and the Curtin Research Scholarship (CRS) for their support. The authors also acknowledge the CHIRI and the use of laboratory equipment, and the scientific and technical assistance of the Curtin University Electron Microscope Facility, which has been partially funded by the University, State and Commonwealth Governments. The authors also acknowledge the Pharmaceutical Technology Laboratory (Curtin School of Pharmacy). The authors are grateful to The University of Western Australia and St. Vincent's Institute of Medical Research (Victoria) for supplying the NIT-1 β-cells.

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.