Extended Latanoprost Release from Commercial Contact Lenses: In Vitro Studies Using Corneal Models

Mohammadi, S., Jones, L., & Gorbet, M. (2014). Extended Latanoprost Release from Commercial Contact Lenses: In Vitro Studies Using Corneal Models. PLoS ONE, 9(9), e106653. https://doi.org/10.1371/journal.pone.0106653In this study, we compared, for the first time, the release of a 432 kDa prostaglandin analogue drug, Latanoprost, from commercially available contact lenses using in vitro models with corneal epithelial cells. Conventional polyHEMA-based and silicone hydrogel soft contact lenses were soaked in drug solution ( solution in phosphate buffered saline). The drug release from the contact lens material and its diffusion through three in vitro models was studied. The three in vitro models consisted of a polyethylene terephthalate (PET) membrane without corneal epithelial cells, a PET membrane with a monolayer of human corneal epithelial cells (HCEC), and a PET membrane with stratified HCEC. In the cell-based in vitro corneal epithelium models, a zero order release was obtained with the silicone hydrogel materials (linear for the duration of the experiment) whereby, after 48 hours, between 4 to 6 of latanoprost (an amount well within the range of the prescribed daily dose for glaucoma patients) was released. In the absence of cells, a significantly lower amount of drug, between 0.3 to 0.5 , was released, (). The difference observed in release from the hydrogel lens materials in the presence and absence of cells emphasizes the importance of using an in vitro corneal model that is more representative of the physiological conditions in the eye to more adequately characterize ophthalmic drug delivery materials. Our results demonstrate how in vitro models with corneal epithelial cells may allow better prediction of in vivo release. It also highlights the potential of drug-soaked silicone hydrogel contact lens materials for drug delivery purposes.The funding for this project was provided by a Collaborative Health Research Project grant (jointly funded by NSERC and CIHR)

The blood compatibility challenge. Part 3: Material associated activation of blood cascades and cells

The final publication is available at Elsevier via https://doi.org/10.1016/j.actbio.2019.06.020. © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Following protein adsorption/activation which is the first step after the contact of material surfaces and whole blood (part 2), fibrinogen is converted to fibrin and platelets become activated and assembled in the form of a thrombus. This thrombus formation is the key feature that needs to be minimized in the creation of materials with low thrombogenicity. Further aspects of blood compatibility that are important on their own are complement and leukocyte activation which are also important drivers of thrombus formation. Hence this review summarizes the state of knowledge on all of these cascades and cells and their interactions. For each cascade or cell type, the chapter distinguishes statements which are in widespread agreement from statements where there is less of a consensus

mSLA-based 3D printing of acrylated epoxidized soybean oil - nano-hydroxyapatite composites for bone repair

Structural bone allografts are used to treat critically sized segmental bone defects (CSBDs) as such defects are too large to heal naturally. Development of biomaterials with competent mechanical properties that can also facilitate new bone formation is a major challenge for CSBD repair. 3D printed synthetic bone grafts are a possible alternative to structural allografts if engineered to provide appropriate structure with sufficient mechanical properties. In this work, we fabricated a set of novel nanocomposite biomaterials consisting of acrylated epoxidized soybean oil (AESO), polyethylene glycol diacrylate (PEGDA) and nanohydroxyapatite (nHA) by using masked stereolithography (mSLA)-based 3D printing. The nanocomposite inks possess suitable rheological properties and good printability to print complex, anatomically-precise, ‘by design’ grafts. The addition of nHA to the AESO/PEGDA resin improved the tensile strength and fracture toughness of the mSLA printed nanocomposites, presumably due to small-scale reinforcement. By adding 10 vol% nHA, tensile strength, modulus and fracture toughness (KIc) were increased to 30.8 ± 1.2 MPa (58% increase), 1984.4 ± 126.7 MPa (144% increase) and 0.6 ± 0.1 MPa·m1/2 (42% increase), respectively (relative to the pure resin). The nanocomposites did not demonstrate significant hydrolytic, enzymatic or oxidative degradation when incubated for 28 days, assuring chemical and mechanical stability at early stages of implantation. Apatite nucleated and covered the nanocomposite surfaces within 7 days of incubation in simulated body fluid. Good viability and proliferation of differentiated MC3T3-E1 osteoblasts were also observed on the nanocomposites. Taken all together, our nanocomposites demonstrate excellent bone-bioactivity and potential for bone defect repair.Canadian Institutes of Health Research || Canada Foundation for Innovation || Ontario Research Fund || University of Waterloo's Engineering Research Initiatives || Natural Sciences & Engineering Research Counci

Impact of contact lens wear on epithelial alterations in keratoconus

Purpose The purpose of this study was to characterize the central epithelial thickness (CET) of penetrating keratoplasty corneal specimens obtained from patients with keratoconus (KC) and correlate the histological patterns with their clinical history.Methods Ex vivo histological imaging was performed to measure CET and total corneal thickness (TCT) in 56 patients with KC. Microscopic slides from penetrating keratoplasty corneal specimens, stained with hematoxylin and eosin were evaluated using bright field microscopy. CET and TCT were measured, and morphological features were studied. Clinical history regarding duration of KC prior to surgery and length of and tolerance to contact lens wear were compared and analyzed. Results The microscopic slides of all patients available for follow up (n = 48) were analyzed and CET and TCT were measured. The histological evaluation revealed 3 distinctive epithelial patterns. Pattern 1 with central hypertrophic and hydropic changes (n = 19) measured 70.89 ± 25.88 μm in CET and 308.63 ± 100.74 μm in TCT; Pattern 2 (n = 14) had not changed, similar to normal epithelium CET and TCT measuring 36.5 ± 7.02 μm and 260.14 ± 87.93 μm respectively. Pattern 3 (n = 15) demonstrated thinner central epithelium characterized by atrophy and focal hydropic changes measuring 19.93 ± 4.60 μm and 268.00 ± 79.39 μm in CET and TCT respectively (all p < 0.0001). The presence of Pattern 2 characterized by similar to normal CET was correlated with the duration of the condition (R = 0.600, p = 0.030). There was a significant difference in the length of CL wear comparing those with patterns 1 and 2 versus 3 (least no. of CL years) (p = 0.05 and p = 0.33 respectivelly). Conclusions Patients with advanced disease have various central corneal epithelial changes detected with histology. Although each central epithelial pattern type was distinctive comparing the 3 patterns, there was no correlation with years of CL wear but only with the duration of the condition.Office of Research of the University of Waterlo

The importance of platelets and complement in material-induced leukocyte activation in vitro

grantor: University of TorontoThe role of material, platelets, and complement on material-induced leukocyte activation was investigated using an 'in vitro' bead (45 [mu]m) assay with polystyrene (PS), polyethylene glycol-immobilized polystyrene (PS-PEG), and PS-PEG-NH2. Blood contact with beads activated leukocytes (tissue factor (TF) expression, CD11b upregulation and association with platelets), resulting in increased procoagulant activity. In the bulk, activation was independent of material surface chemistry; activation of adherent leukocytes was material-dependent. In blood, tissue factor expression on monocytes, but not CD11b upregulation on leukocytes in the bulk, was independent of material surface area. Material-induced TF expression, but not CD11b upregulation, required the presence of platelets. In fact, TF expression was dependent on the association between platelets and monocytes. Both anti-IIb/IIIa and anti-P-selectin reduced TF expression. Inhibiting complement alone with sCR1 (a specific complement inhibitor) was without effect on material-induced TF expression. However, combining sCR1 and the platelet antagonist anti-GPIIb/IIIa significantly reduced material-induced TF expression in blood. Complement inhibition with sCR1 was only effective in reducing CD11b upregulation in the bulk in the presence of a material that strongly activated complement, such as PS-PEG, but not with the moderate activator PS. When effective, complement inhibition with sCR1 only partially reduced material-induced CD11b upregulation in the bulk, suggesting that other mechanisms exist. Platelet activation was identified as the other mechanism contributing to material-induced CD11b upregulation in blood. Inhibiting both complement (with sCR1) and platelets (with anti-GPIIb/IIIa) blocked material-induced CD11 b upregulation. The presence of pyridoxal-5-phosphate alone also significantly reduced both TF expression and CD11b upregulation in the bulk; this is believed to be associated with its C1q and platelet inhibitory activities. Both adsorbed complement products and adherent platelets mediated leukocyte adhesion. TF expression on adherent monocytes was strongly dependent on the presence of adherent platelets, while adsorbed complement products regulated CD1b upregulation on adherent leukocytes. 'In vitro' material-induced leukocyte activation, associated with the expression of procoagulant activities, appeared to be secondary to both complement and platelet activation. Blood-material compatibility may be greatly improved with a material that minimally activates both platelets and complement, or by the use of therapeutic agents, such as P5P, that simultaneously inhibit platelets and complement.Ph.D

The Differential Reactive Oxygen Species Production of Tear Neutrophils in Response to Various Stimuli In Vitro

A large number of polymorphonuclear neutrophils (PMNs) invade the ocular surface during prolonged eye closure (sleep); these leukocytes are commonly referred as tear PMNs. PMNs contribute to homeostasis and possess an arsenal of inflammatory mediators to protect against pathogens and foreign materials. This study examined the ability of tear PMNs to generate reactive oxygen species (ROS), an essential killing mechanism for PMNs which can lead to oxidative stress and imbalance. Cells were collected after sleep from healthy participants using a gentle eye wash. ROS production in stimulated (phorbol-12-myristate-13-acetate (PMA), lipopolysaccharides (LPS) or N-Formylmethionyl-leucyl-phenylalanine (fMLP)) and unstimulated tear PMNs was measured using luminol-enhanced chemiluminescence for 60 min. A high level of constitutive/spontaneous ROS production was observed in tear PMNs in the absence of any stimulus. While tear PMNs were able to produce ROS in response to PMA, they failed to appropriately respond to LPS and fMLP, although fMLP-stimulated tear PMNs generated ROS extracellularly in the first three minutes. Higher ROS generation was observed in isolated tear PMNs which may be due to priming from the magnetic bead cell separation system. The differential responses of tear PMNs in ROS generation provide further evidence of their potential inflammatory roles in ocular complications involving oxidative stress

Time course of latanoprost release from galyfilcon A contact lens through live and dead monolayer models.

<p>Cells were killed by fixing in Paraformaldehyde. Lenses were soaked for 24 hours in drug solution () and then overlayed on the model for 24 hours. Release experiments through fixed monolayer were conducted in two separate dates (n = 2, Mean SD). The results were compared to release through monolayer models, (n = 6 Mean SD).</p

Latanoprost Free-Acid Release from Tested Commercial Contact Lenses after 24 Hours.

<p>n = 6, Mean Standard Deviation. Concentration of latanoprost were measured using EIA.</p><p>No-Cell Model: Cell culture inserts (PET membrane) without cells, Monolayer Model: PET insert with a monolayer of human corneal epithelial cells, Multilayer Model: PET insert with a multilayer of human corneal epithelial cells (stratified culture).</p>†<p>The release as a percentage of uptake has been calculated based on the ratio of the released concentration over the sorbed amount.</p>#<p>Significantly different from other contact lens materials (silicone hydrogel) .</p><p>*Significantly different from the amount released by respective materials in the no-cells model .</p><p>Latanoprost Free-Acid Release from Tested Commercial Contact Lenses after 24 Hours.</p