Current status and applications of animal models in pre-clinical development of orally administered insulin-loaded nanoparticles

Abstract

Oral delivery of insulin-loaded therapeutics is challenging due to the extreme pH condition, enzymatic degradation, and limited permeation in the gastrointestinal (GI) tract. Nanoparticles can overcome various GI barriers and improve the oral bioavailability of insulin. Although a number of novel strategies have been reported to optimise the orally administered nano-formulation, its clinical translation remains unachievable. Animal studies are essential to establish the protective effect, transit behaviour, retention time, mucoadhesiveness degree, absorption mechanism and distribution of nanoparticle in the GI tract. In this review, we examine various instrumentations, such as Ussing chamber, fluorescence microscope, TEM, CLSM, that are available for investigating the ex vivo intestinal absorption and mucoadhesive capability of insulin-loaded nanoparticles. More importantly, a comprehensive understanding and evaluation of in vivo animal studies are crucial to clarify the physiological properties of insulin nanoparticles. In addition, the biocompatibility of nanoparticle is a critical prerequisite for short-term and long-term use of drug formulation. The success of oral nanomedicine should improve the bioavailability of insulin and elicit no damage to internal organs. Lastly, we reviewed the current status of animal assays, including mucoadhesiveness study, biocompatibility (integrity of intestinal mucosa, histological analysis, oxidative stress, physical symptoms), biodistribution (fluorescence imaging, SPECT) and in vivo efficacy study, for the evaluation of orally administered insulin-loaded nanoparticles in pre-clinical stage.

Keywords:

• Animal
• biocompatibility
• biodistribution
• insulin
• nanoparticles
• oral
• pre-clinical
• protein
• pharmacokinetics

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This paper was not prepared with a specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Wong acknowledges the support from Australian Government through Australian Government Research Training Programme Scholarship. Al-Salami is partially supported by the European Union’s Horizon 2020 SALSETH research and innovation programme under the Marie Skłodowska-Curie grant agreement No 872370.