Evaluation of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer nanomicelle for trigeminal ganglion neurons delivering with intranasal administration

Lipopolysaccharide-induced Trigeminal Ganglion Nerve Fiber Damage is Associated with Autophagy Inhibition

OBJECTIVE

This study aimed to determine whether lipopolysaccharide (LPS) induces the loss of corneal nerve fibers in cultured trigeminal ganglion (TG) cells, and the underlying mechanism of LPS-induced TG neurite damage.

METHODS

TG neurons were isolated from C57BL/6 mice, and the cell viability and purity were maintained for up to 7 days. Then, they were treated with LPS (1 µg/mL) or the autophagy regulator (autophibib and rapamycin) alone or in combination for 48 h, and the length of neurites in TG cells was examined by the immunofluorescence staining of the neuron-specific protein β3-tubulin. Afterwards, the molecular mechanisms by which LPS induces TG neuron damage were explored.

RESULTS

The immunofluorescence staining revealed that the average length of neurites in TG cells significantly decreased after LPS treatment. Importantly, LPS induced the impairment of autophagic flux in TG cells, which was evidenced by the increase in the accumulation of LC3 and p62 proteins. The pharmacological inhibition of autophagy by autophinib dramatically reduced the length of TG neurites. However, the rapamycin-induced activation of autophagy significantly lessened the effect of LPS on the degeneration of TG neurites.

CONCLUSION

LPS-induced autophagy inhibition contributes to the loss of TG neurites.

A nano-phytochemical ophthalmic solution for marked improvement of corneal wound healing in healthy or diabetic mice

Aim: To formulate a novel nano-phytochemical ophthalmic solution to promote corneal wound healing. Methods: Dipotassium glycyrrhizinate (DG) and palmatine (PAL) were used to formulate this formulation marked as DG-PAL, and its efficacy and mechanisms for promoting corneal wound healing were evaluated in mice. Results: DG-PAL was easily fabricated with excellent physical profiles. In in vivo efficiency evaluations, DG-PAL demonstrated an excellent promoting effect on corneal epithelial/nerve wound healing in both healthy and diabetic mice. These effects were involved in the DG-PAL-induced decreased expression levels of HMGB1 and its signaling-related factors in the corneas and trigeminal neurons of the healthy or diabetic mice. Conclusion: DG-PAL possibly represents a promising ophthalmic solution for promoting corneal wound healing.

New resveratrol micelle formulation for ocular delivery: characterization and in vitro/in vivo evaluation

Many eye diseases, such as corneal wound healing after injury, involve oxidative stress and inflammatory responses; however, many efficient natural antioxidants (e.g. resveratrol) have limited application in ophthalmology due to their poor solubility, low stability and poor ocular bioavailability. In this work, the aim was to formulate resveratrol into a micelle ophthalmic solution for efficient delivery to the eye. A Soluplus micelle ophthalmic solution containing resveratrol (Sol-Res) was formulated and optimized with a small and uniform dispersion in an ophthalmic solution. Sol-Res did not show any cell toxicity but promoted cell proliferation in both the short- and long-term cytotoxicity tests. The in vivo eye irritation test also verified the well ocular tolerance of the Sol-Res ophthalmic solution. The chemical stability of resveratrol in micelles in an aqueous solution was greatly improved over the free resveratrol solution, and Sol-Res also showed a good storage stability in the short-term storage stability test. Sol-Res showed improved in vitro passive permeation, in vitro cellular uptake, and in vivo corneal permeation over the free Res suspension solution. Furthermore, Sol-Res favored in vivo corneal wound healing, and the inhibition of key anti-inflammation mediators and the production of antioxidant factors in mRNA expression was observed in the Sol-Res treated wound healing corneas, suggesting that the mechanisms that regulate proinflammatory cytokines and oxidative stress might be involved in its therapeutic effect. Therefore, Sol-Res might be a promising candidate for further clinical application.

Micelles: Promising Ocular Drug Carriers for Anterior and Posterior Segment Diseases

Micelles have been studied in the targeting of drug substances to different tissues as a nano-sized delivery system for many years. Sustained drug release, ease of production, increased solubility, and bioavailability of drugs with low water solubility are the most important superiorites of micellar carriers. These advantages paved the way for the use of micelles as a drug delivery system in the ocular tissues. The unique anatomical structure of the eye as well as its natural barriers and physiology affect ocular bioavailability of the drugs negatively. Conventional dosage forms can only reach the anterior segment of the eye and are used for the treatment of diseases of this segment. In the treatment of posterior segment diseases, conventional dosage forms are administered sclerally, via an intravitreal injection, or systemically. However, ocular irritation, low patient compliance, and high side effects are also observed. Micellar ocular drug delivery systems have significant promise for the treatment of ocular diseases. The potential of micellar systems ocular drug delivery has been demonstrated by in vivo animal experiments and clinical studies, and they are continuing extensively. In this review, the recent research studies, in which the positive outcomes of micelles for ocular targeting of drugs for both anterior and posterior segment diseases as well as glaucoma has been demonstrated by in vitro, ex vivo, or in vivo studies, are highlighted.

New micelle myricetin formulation for ocular delivery: improved stability, solubility, and ocular anti-inflammatory treatment

Myricetin (Myr) is a naturally occurring flavonoid exhibiting diverse biological and pharmacological properties, but its characteristics such as water insolubility, poor aqueous stability, and poor bioavailability limit its clinical application, including in ophthalmology. To increase its clinical application in ophthalmology, Myr was designed to be encapsulated in a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PVCL-PVA-PEG) polymeric micelles to increases its aqueous solubility, stability, and corneal permeability to promote its efficacy in eye disease treatments. Thus, the Myr micelle ophthalmic solution was prepared and characterized encapsulation efficiency (EE), micelle size, and zeta potential. The chemical stability of Myr and the short-term storage stability of the Myr micelle ophthalmic solution were evaluated, followed by in vitro cytotoxicity and in vivo ocular irritation; in vitro cellular uptake and in vivo corneal permeation; and in vitro antioxidant activity and in vivo anti-inflammatory efficacy were also further evaluated. Myr could be incorporated into micelles with high EE. PVCL-PVA-PEG micelles significantly enhanced Myr's aqueous solubility and chemical stability. The Myr micelle ophthalmic solution also showed high storage stability. In rabbits, the Myr micelle ophthalmic solution displayed good in vitro cellular tolerance. Remarkable improvements in in vitro cellular uptake and in vivo corneal permeation were also observed in the Myr micelle ophthalmic solution, and significant improvements in the in vitro antioxidant activity and in vivo anti-inflammatory efficacy were also obtained. Overall, these results supported that the Myr micelle ophthalmic solution could be a promising nanomedicine for ocular tissues.