Long term therapeutic effects of icariin-loaded PLGA microspheres in an experimental model of optic nerve ischemia via modulation of CEBP-ß/G-CSF/noncanonical NF-κB axis.

An ischemic insult at optic nerve (ON) is followed by detrimental neuroinflammation that results in progressive and long-lasting retinal ganglion cell (RGC) death and vision loss. Icariin was reported to be a safe and effective natural anti-inflammatory drug. Herein, we evaluated the long-term therapeutic effects of a single intravitreal injection of poly(lactide-co-glycolide) PLGA-icariin in a rat model of anterior ischemic optic neuropathy (rAION). Treatment with PLGA microspheres of icariin preserved the visual function and RGC density for 1 month in the rAION model. In addition, ON edema and macrophage infiltration were inhibited by treating PLGA microspheres of icariin. We found that the binding complex of icariin and CCAAT enhancer binding protein beta (CEBP-ß) significantly induced endogenous granulocyte colony-stimulating factor (G-CSF) expression to activate noncanonical nuclear factor kappa B (NF-κB) signaling pathway by promoting an alternative phosphorylation reaction of IKK-ß. Activation of noncanonical NF-κB signaling pathway promoted the M2 microglia/macrophage polarization and AKT1 activation, which prevented neuroinflammation and RGC apoptosis after ON infarct. This study concluded that protective mechanism of icariin is a CEBP-ß/G-CSF axis-induced noncanonical NF-κB activation, which provides the long-term neuroprotective effects via anti-inflammatory and antiapoptotic actions after ON ischemia.

A Novel Eye Drop Formulation for Potential Treatment of Neovascular Age-Related Macular Degeneration.

Purpose: Drug delivery to posterior ocular tissues via topical eye drop administration is arduous due to the unique anatomy and physiology of the eye. Therefore, treatments for posterior eye disease have to be administered via intravitreal injection or systemic route, both of which have their drawbacks. Herein, the objective of this work was to demonstrate that a specially designed eye drop formulation could effectively deliver small-molecule vascular endothelial growth factor (VEGF) inhibitor to posterior ocular tissues for antiangiogenic therapy. Methods: The unique eye drop formulation, termed ITRI AXN eye drops, was obtained from self-assembly of (2-hydroxypropyl)-ß-cyclodextrin with a VEGF tyrosine kinase inhibitor, a hydrophilic polymer, hypromellose, and a complex stabilizer, caffeine. In vivo ocular pharmacokinetics studies were performed with New Zealand White (NZW) rabbits and Non Human Primates (NHP). The antiangiogenesis effect was evaluated on the Long-Evans rat with laser-induced choroidal neovascularization and pigmented Dutch-Belted rabbits with VEGF-induced retinal neovascularization. Results: The successful drug transport from ocular surface to posterior ocular cavity was indicated by a drug biodistribution pattern in pharmacokinetic studies. Excellent drug exposure in the choroid and retina with the concentrations of 900- and 750-fold greater than drug IC50 0.5 hours post the eye drop administration (drug level: 0.8%) was observed on the NHP study. The obtained formulation also demonstrated a comparable antiangiogenic outcome with the intravitreal injection of anti-VEGF antibody on rat and rabbit disease models. Conclusions: Our eye drop formulation has demonstrated great promise in antiangiogenic therapy against retinal and choroidal neovascularization in animal models. The results suggest that the aim of this work can be successfully achieved by the novel eye drop formulation. Translational Relevance: The preclinical results provide evidence that ITRI AXN eye drops could effectively deliver therapeutics to the choroid and retina for antiangiogenic therapy.

The Intraocular Pressure Lowering Effect of a Dual Kinase Inhibitor (ITRI-E-(S)4046) in Ocular Hypertensive Animal Models.

Purpose: The purpose of this study was to develop a preclinical compound, ITRI-E-(S)4046, a dual synergistic inhibitor of myosin light chain kinase 4 (MYLK4) and Rho-related protein kinase (ROCK), for reducing intraocular pressure (IOP). Methods: ITRI-E-(S)4046 is an amino-pyrazole derivative with physical and chemical properties suitable for ophthalmic formulation. In vitro kinase inhibition was evaluated using the Kinase-Glo Luminescent Kinase Assays. A comprehensive kinase selectivity analysis of ITRI-E-(S)4046 was performed using the KINOMEscan assay from DiscoverRx. The IOP reduction and tolerability of ITRI-E-(S)4046 were assessed in ocular normotensive rabbits, ocular normotensive non-human primates, and ocular hypertensive rabbits. In vivo studies were conducted to assess drug concentrations in ocular tissue. The adverse ocular effects of rabbit eyes were evaluated following the OECD405 guidelines. Results: ITRI-E-(S)4046 showed highly selective kinase inhibitory activity against ROCK1/2, MYLK4, and mitogen-activated protein kinase kinase kinase 19 (MAP3K19), with high specificity against protein kinase A, G, and C families. In ocular normotensive rabbits and non-human primates, the mean IOP reductions of 0.1% ITRI-E-(S)4046 eye drops were 29.8% and 28.5%, respectively. In hypertonic saline-induced and magnetic beads-induced ocular hypertensive rabbits, the mean IOP reductions of ITRI-E-(S)4046 0.1% eye drops were 46.9% and 22.0%, respectively. ITRI-E-(S)4046 was well tolerated with only temporary and minor signs of hyperemia. Conclusions: ITRI-E-(S)4046 is a novel type of highly specific ROCK1/2 and MYLK4 inhibitor that can reduce IOP in normotensive and hypertensive animal models. It has the potential to become an effective and well-tolerated treatment for glaucoma.

Hyperthermia-mediated local drug delivery by a bubble-generating liposomal system for tumor-specific chemotherapy.

As is widely suspected, lysolipid dissociation from liposomes contributes to the intravenous instability of ThermoDox (lysolipid liposomes), thereby impeding its antitumor efficacy. This work evaluates the feasibility of a thermoresponsive bubble-generating liposomal system without lysolipids for tumor-specific chemotherapy. The key component in this liposomal formulation is its encapsulated ammonium bicarbonate (ABC), which is used to actively load doxorubicin (DOX) into liposomes and trigger a drug release when heated locally. Incubating ABC liposomes with whole blood results in a significantly smaller decrease in the retention of encapsulated DOX than that by lysolipid liposomes, indicating superior plasma stability. Biodistribution analysis results indicate that the ABC formulation circulates longer than its lysolipid counterpart. Following the injection of ABC liposome suspension into mice with tumors heated locally, decomposition of the ABC encapsulated in liposomes facilitates the immediate thermal activation of CO2 bubble generation, subsequently increasing the intratumoral DOX accumulation. Consequently, the antitumor efficacy of the ABC liposomes is superior to that of their lysolipid counterparts. Results of this study demonstrate that this thermoresponsive bubble-generating liposomal system is a highly promising carrier for tumor-specific chemotherapy, especially for local drug delivery mediated at hyperthermic temperatures.

In vitro and in vivo imaging of peptide-encapsulated polymer nanoparticles for cancer biomarker activated drug delivery.

Gelatin nanoparticles coated with Cathepsin D-specific peptides were developed as a vehicle for the targeted delivery of the cancer drug doxorubicin (DOX) to treat breast malignancy. Cathepsin D, a breast cancer cell secretion enzyme, triggered the release of DOX by digesting the protective peptide-coating layer of nanoparticles. Fabricated nanoparticles were successfully detected with ultrasound imaging in both in vitro conditions and in vivo mouse cancer models. Cell viability experiments were conducted to determine the efficacy of biomarker activation specific to breast cancer cell lines. These experimental results were compared with the outcome of a viability experiment conducted on noncancerous cells. Viability decreased in human MCF7 mammary adenocarcinoma and mouse 4T1 mammary carcinoma cells, while that of noncancerous 3T3 fibroblast cells remained unaffected. Next, a real-time video of nanoparticle flow in mouse models was obtained using in vivo ultrasound imaging. The fluorescent profile of DOX was used as a means to examine nanoparticle localization in vivo. Results show the distribution of nanoparticles concentrated primarily within bladder and tumor sites of subject mice bodies. These findings support the use of biomarker coated nanoparticles in target specific therapy for breast cancer treatment.

The effect of biodegradable gelatin microspheres on the neuroprotective effects of high mobility group box 1 A box in the postischemic brain.

High mobility group box 1 (HMGB1) is a family of endogenous molecules that is released by necrotic cells and causes neuronal damages by triggering inflammatory processes. In the cerebral ischemic brain, sustained and regulated suppression of HMGB1 has been emerged as a therapeutic means to grant neuroprotection. HMGB1 consists of two HMG boxes (A and B) and an acidic C-terminal tail, and the A box peptide antagonistically competes with HMGB1 for its receptors. In the middle cerebral artery occlusion (MCAO) in rats, a murine model of transient cerebral ischemia, administration of HMGB1 A box intraparenchymally, after encapsulated in biodegradable gelatin microspheres (GMS), which enhances the stability of peptide inside and allows its sustained delivery, at 1 h, 3 h, or 6 h after MCAO, reduced mean infarct volumes by, respectively, 81.3%, 42.6% and 30.7% of the untreated MCAO-brain, along with remarkable improvement of neurological deficits. Furthermore, the administration of HMGB1 A box/GMS suppressed proinflammatory cytokine inductions more strongly than the injection of non-encapsulated HMGB1 A box. Given that insulted brains-like ischemia have enhanced gelatinase activity than the normal brain, our results suggest that GMS-mediated delivery of therapeutic peptides is a promising means to provide efficient neuroprotection in the postischemic brain.

Modeling of small-molecule release from crosslinked hydrogel microspheres: effect of crosslinking and enzymatic degradation of hydrogel matrix.

A diffusion-based model describing the drug release from a charged hydrogel (gelatin) microsphere undergoing enzymatic degradation is presented. The model elucidates the effect of glutaraldehyde, a crosslinking agent, on the release profile in terms of the initial drug distribution, diffusivity of the drug, degradation rate of gelatin and its ability to form polyionic complex with the drug. The model was validated by comparing with in vitro release of trypan blue, an acidic model drug, from basic gelatin microspheres. While drug release was not a simple function of glutaraldehyde concentration, the effective diffusivity was found to be inversely proportional to glutaraldehyde concentration in the form of a power function when the initial drug distribution was taken into consideration. For these reasons, the present model can accurately predict drug release with no adjustable parameters, given the collagenase concentration. The present model may help design certain release scenarios from biodegradable charged hydrogels for the oppositely charged drugs and biomolecules.

Uniform chitosan microspheres for potential application to colon-specific drug delivery.

Uniform chitosan microspheres have been fabricated and weakly crosslinked for potential applications in colon-specific drug delivery. The effects of microsphere size, crosslinking density and electrostatic interactions between the drug and chitosan on drug release were studied, employing model drugs of different acidities. When the drug was basic, all chitosan spheres exhibited 100% release within 30 min. As the acidity of the drug increased, the release slowed down and depended on the crosslinking density and microsphere size. The release of weakly acidic drug was most suppressed for large spheres (35-38 microm), while the small spheres (23-25 microm) with higher crosslinking exhibited the most retention of highly acidic drug, indicating that they are a promising candidate for colon-specific delivery.

Monodisperse gelatin microspheres as a drug delivery vehicle: release profile and effect of crosslinking density.

Uniform gelatin microspheres (GMS) of a wet size of 100 microm in diameter were fabricated by the electric field assisted precision particle fabrication (E-PPF) method and crosslinked with different glutaraldehyde (GA) concentrations to study the effect of the crosslinking density on drug release. The drug release profiles of the crosslinked GMS were studied along with the intraparticle drug distribution and the particle degradation characteristics. Due to the concentration gradient of GA along the diffusion path into the GMS, the crosslinking density is higher on the GMS surface, making it less susceptible to degradation. As a result, the GMS with higher GA concentrations (0.375-0.875%) exhibited a highly resistant surface toward enzymatic degradation. On the other hand, the amount of drug complexation at the surface decreases as the GA concentration increases, which can be attributed to the lowered basicity of gelatin caused by the increased crosslinking density. These factors collectively affect the drug release kinetics and give rise to similar release profiles for GMS above a GA concentration of 0.375%.