Deep Tissue Penetration of Bottle-Brush Polymers via Cell Capture Evasion and Fast Diffusion.

Drug nanocarriers (NCs) capable of crossing the vascular endothelium and deeply penetrating into dense tissues of the CNS could potentially transform the management of neurological diseases. In the present study, we investigated the interaction of bottle-brush (BB) polymers with different biological barriers in vitro and in vivo and compared it to nanospheres of similar composition. In vitro internalization and permeability assays revealed that BB polymers are not internalized by brain-associated cell lines and translocate much faster across a blood-brain barrier model compared to nanospheres of similar hydrodynamic diameter. These observations performed under static, no-flow conditions were complemented by dynamic assays performed in microvessel arrays on chip and confirmed that BB polymers can escape the vasculature compartment via a paracellular route. BB polymers injected in mice and zebrafish larvae exhibit higher penetration in brain tissues and faster extravasation of microvessels located in the brain compared to nanospheres of similar sizes. The superior diffusivity of BBs in extracellular matrix-like gels combined with their ability to efficiently cross endothelial barriers via a paracellular route position them as promising drug carriers to translocate across the blood-brain barrier and penetrate dense tissue such as the brain, two unmet challenges and ultimate frontiers in nanomedicine.

Gelatin-based membrane containing usnic acid-loaded liposomes: A new treatment strategy for corneal healing.

PURPOSE: To evaluate the safety and potential healing efficacy of the topical ocular administration of a gelatin membrane containing usnic acid/liposomes (UALs) for corneal cicatrization. UALs have shown healing activity in animal models of dermal burn lesions. We evaluated the safety of topical ocular administration of UAL and its potential healing efficacy as an ophthalmic treatment on chemical lesions in rabbit eyes. METHOD: The Draize test was used to check for ocular toxicity and the score was zero at each observation, indicating the ocular safety of a gelatin membrane containing usnic acid/liposome. Its potential healing efficacy as an ophthalmic treatment on chemical lesions in rabbit eyes was also assessed. RESULTS: After epithelial removal and treatment with UAL, there was a 49.4 % reduction in injury under in vivo conditions compared with a 36.6 % reduction in the control, a gelatin membrane containing liposome without usnic acid. Histological analysis of ocular surface chemical injury-tissue sections after treatment with UAL supported these observations. The corneal expression of VEGF and TGF-ß1increased by 70 % and 50 % respectively following treatment with UAL gelatin membrane. CONCLUSION: These results indicate the potential therapeutic application of UAL gelatin membranes as an ophthalmic treatment that may be used for corneal cicatrization.

Treatment for chemical burning using liquid crystalline nanoparticles as an ophthalmic delivery system for pirfenidone.

Some recent studies have shown that pirfenidone (PFD) has favorable results in the healing process of the cornea. However, PFD in solution exhibits short half-life after topical application, and in this context, a liquid crystal nanoparticle system containing PFD (PFD-LCNPs) was developed. The nanoparticles were characterized by transmission electron microscopy, atomic force microscopy, small angle X-ray diffraction and polarized light microscopy. The PFD-LCNPs had particle size and zeta potential of 247.3 nm and -33.60 mV (stores at 4 °C), respectively, and 257.5 nm and -46.00 mV (stored at 25 °C), respectively. The pH of the formulation was 6.9 and the encapsulation efficiency was 35.9%. The in vitro release profiles indicated that PFD sustained release from PFD-LCNPs for up to 12 h. In vitro study of ocular irritation (HET-CAM test) concluded that components of the formulation are well tolerated for ocular administration. Corneal re-epithelialization time after chemical burning was significantly reduced in rabbits treated with PFD-loaded LCNPs when compared to the group treated with a vehicle. In addition, the anti-inflammatory action of pirfenidone was observed by reducing myeloperoxidase activity (MPO) and inflammatory cells in the histology of the tissues of animals treated with PFD-LCNPs. These findings indicated that the PFD-LCNPs might have the potential for effective ocular drug delivery.

A New Topical Eye Drop Containing LyeTxI-b, A Synthetic Peptide Designed from A Lycosa erithrognata Venom Toxin, Was Effective to Treat Resistant Bacterial Keratitis.

Bacterial keratitis is an ocular infection that can lead to severe visual disability. Staphylococcus aureus is a major pathogen of the eye. We recently demonstrated the strong antimicrobial activity of LyeTxI-b, a synthetic peptide derived from a Lycosa erithrognatha toxin. Herein, we evaluated a topical formulation (eye drops) containing LyeTxI-b to treat resistant bacterial keratitis. Keratitis was induced with intrastromal injection of 4 × 105 cells (4 µL) in New Zealand female white rabbits. Minimum inhibitory concentration (MIC) and biofilm viability were determined. LyeTxI-b ocular toxicity was evaluated through chorioallantoic membrane and Draize tests. One drop of the formulation (LyeTxI-b 28.9 µmol/L +0.5% CMC in 0.9% NaCl) was instilled into each eye four times a day, for a week. Slit-lamp biomicroscopy analysis, corneal histopathological studies and cellular infiltrate quantification through myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) detection were performed. LyeTxI-b was very effective in the treatment of keratitis, with no signs of ocular toxicity. Planktonic bacteria MIC was 3.6 µmol/L and LyeTxI-b treatment reduced biofilm viability in 90%. LyeTxI-b eliminated bacteria and reduced inflammatory cellular activity in the eyes. Healthy and treated animals showed similar NAG and MPO levels. LyeTxI-b is a potent new drug to treat resistant bacterial keratitis, showing effective antimicrobial and anti-inflammatory activity.

Intravitreal injection of the synthetic peptide LyeTx I b, derived from a spider toxin, into the rabbit eye is safe and prevents neovascularization in a chorio-allantoic membrane model.

BACKGROUND: The great diversity of molecules found in spider venoms include amino acids, polyamines, proteins and peptides, among others. Some of these compounds can interact with different neuronal receptors and ion channels including those present in the ocular system. To study potential toxicity and safety of intravitreal injection in rabbits of LyeTx I b, a synthetic peptide derived from the toxin LyeTx I found in venom from the spider Lycosa eritrognatha and to evaluate the angiogenic activity on a CAM model. METHODS: ARPE-19 cells were treated with LyeTx I b (0.36; 0.54; 0.72; 2.89; 4.34 or 9.06 µM). In this study, New Zealand rabbits were used. LyeTx I b (2.89 µM) labeled with FITC dissolved in PBS, or only PBS, were injected into vitreous humor. Electroretinogram (ERG) was recorded 1 day before injection and at 7, 14 and 28 days post-injection. Clinical examination of the retina was conducted through tonometer and eye fundus after ERG. Eyes were enucleated and retinas were prepared for histology in order to assess retinal structure. CAMs were exposed to LyeTx I b (0.54; 0.72; 2.17 or 2.89 µM). RESULTS: ARPE-19 cells exposed to LyeTx I b showed cell viability at the same levels of the control. The fluorescence of LyeTx I b labeled with FITC indicated its retinal localization. Our findings indicate ERG responses from rats injected in the eye with LyeTx I b were very similar to the corresponding responses of those animals injected only with vehicle. Clinical examination found no alterations of intraocular pressure or retinal integrity. No histological damage in retinal layers was observed. CAM presented reduced neovascularization when exposed to LyeTx I b. CONCLUSIONS: Intravitreal injection of LyeTx I b is safe for use in the rabbit eye and prevents neovascularization in the CAM model, at Bevacizumab levels. These findings support intravitreal LyeTx I b as a good candidate to develop future alternative treatment for the retina in neovascularization diseases.