Abstract: While fibroin isolated from the cocoons of domesticated silkworm Bombyx mori supports growth of human corneal limbal epithelial (HLE) cells, the mechanism of cell attachment remains unclear. In the present study we sought to enhance the attachment of HLE cells to membranes of Bombyx mori silk fibroin (BMSF) through surface functionalization with an arginine-glycine-aspartic acid (RGD)-containing peptide. Moreover, we have examined the response of HLE cells to BMSF when blended with the fibroin produced by a wild silkworm, Antheraea pernyi, which is known to contain RGD sequences within its primary structure. A procedure to isolate A. pernyi silk fibroin (APSF) from the cocoons was established, and blends of the two fibroins were prepared at five different BMSF/APSF ratios. In another experiment, BMSF surface was modified by binding chemically the GRGDSPC peptide using a water-soluble carbodiimide. Primary HLE were grown in the absence of serum on membranes made of BMSF, APSF, and their blends, as well as on RGD-modified BMSF. There was no statistically significant enhancing effect on the cell attachment due to the RGD presence. This suggests that the adhesion through RGD ligands may have a complex mechanism, and the investigated strategies are of limited value unless the factors contributing to this mechanism become better known.
Abstract: Sequestration of harmful proteases as human neutrophil elastase (HNE) from the chronic wound environment is an important goal of wound dressing design and function. Monosaccharides attached to cellulose conjugates as ester-appended aldohexoses and ketohexoses were prepared on cotton gauze as monosccharide-citrate-cellulose-esters for HNE sequestration. The monosaccharide-cellulose analogs demonstrated selective binding when the derivatized cotton dressings were measured for sequestration of HNE. Each monosaccharide-cellulose conjugate was prepared as a cellulose citrate-linked monosaccharide ester on the cotton wound dressing, and assayed under wound exudate-mimicked conditions for elastase sequestration activity. A series of three aldohexose and four ketohexose ester cellulose conjugates were prepared on cotton gauze through citric acid-cellulose cross linking esterification. The monosaccharide portion of the conjugate was characterized by hydrolysis of the citrate-monosaccharide ester bond, and subsequent analysis of the free monosaccharide with high performance anion exchange chromatography. The ketohexose and aldohexose conjugate levels on cotton were quantified on cotton using chromatography and found to be present in milligram/gram amounts. The citrate-cellulose ester bonds were characterized with FTIR. Ketohexose-citrate-cellulose conjugates sequestered more elastase activity than aldohexose-citrate-cellulose conjugates. The monosaccharide cellulose conjugate families each gave distinctive profiles in elastase-lowering effects. Possible mechanisms of elastase binding to the monosaccharide-cellulose conjugates are discussed.
Abstract: Human corneal endothelial cells have a limited ability to replicate in vivo and in vitro. Allograft transplantation becomes necessary when an accident or trauma results in excessive cell loss. The reconstruction of the cornea endothelium using autologous cell sources is a promising alternative option for therapeutic or in vitro drug testing applications. The native corneal endothelium rests on the Descemet’s membrane, which has nanotopographies of fibers and pores. The use of synthetic topographies mimics the native environment, and it is hypothesized that this can direct the behavior and growth of human microvascular endothelial cells (HMVECs) to resemble the corneal endothelium. In this study, HMVECs are cultivated on substrates with micron and nano-scaled pillar and well topographies. Closely packed HMVEC monolayers with polygonal cells and well-developed tight junctions were formed on the topographical substrates. Sodium/potassium (Na+/K+) adenine triphosphatase (ATPase) expression was enhanced on the microwells substrate, which also promotes microvilli formation, while more hexagonal-like cells are found on the micropillars samples. The data obtained suggests that the use of optimized surface patterning, in particular, the microtopographies, can induce HMVECs to adopt a more corneal endothelium-like morphology with similar barrier and pump functions. The mechanism involved in cell contact guidance by the specific topographical features will be of interest for future studies.
Abstract: For the purpose of developing a novel ablation therapy for oral cancer, the heat generation and transfer properties of a Ti-coated carbon steel rod with 20-mm length and 1.8-mm outer diameter were investigated by means of a high-frequency induction technique at 300 kHz. The heat generation measurement performed using water (15 mL) revealed that the difference of the inclination angles (θ = 0°, 45° and 90°) relative to the magnetic flux direction only slightly affects the heating behavior, exhibiting the overlapped temperature curves during an induction time of 1200 s. These results suggest that the effect of the shape magnetic anisotropy is almost eliminated, being convenient for the precise control of the ablation temperature in clinical use. In the experiments utilizing a tissue-mimicking phantom, the heat transfer concentrically occurred in the lateral direction for both the planar surface and a 10-mm deep cross-section. However, the former exhibited a considerably lower increase in temperature (ΔT), probably due to the effect of heat dissipation to the ambient air. No significant heat transfer was found to occur to the lower side of the inserted Ti-coated carbon steel rod, which is situated in the longitudinal direction.
Abstract: The capsule drug ring (CDR) is a reservoir and delivery agent, which is designed to be placed within the capsular bag during cataract surgery. Prototypes were manufactured by hot melt extrusion of Bionate II®, a polycarbonate urethane. The devices have been optimized using Avastin® as the drug of interest. In vitro biocompatibility was assessed with human lens epithelial cell (B-3), mouse macrophage (J774A.1) and mouse fibroblast (L-929) cell lines. Cell migration and proliferation were assessed after in vitro culture. Pro-inflammatory cytokines (i.e., MIP-1β, MIP-1α, MCP-1, IL-1β, TNF and TGF-β1) were quantified using cytometric bead array (CBA). Preliminary in vivo biocompatibility and pharmacokinetics testing has been performed in rabbits.
Abstract: To investigate the temporary tamponade effects of an ophthalmic viscosurgical device (OVD) for experimental retinal tears, we performed vitrectomy in four rabbit eyes and created a posterior vitreous detachment and artificial retinal tear to produce retinal detachment. The retina was flattened with liquid perfluorocarbon (PFC), the area peripheral to the tear was photocoagulated, an OVD was applied to the retinal tear surface below the PFC and the PFC was removed by aspiration. In the control group, PFC was removed without application of OVD. At one, three and seven days postoperatively, funduscopy and optical coherence tomography (OCT) were performed to examine the sealing process of the retinal tear. In OVD-treated eyes, the OVD remained on the retinal surface, and the retinal tear was patched for ≥ 3 days postoperatively. By seven days postoperatively, the OVD on the retinal surface had disappeared, and the retina was reattached. In control eyes, the edge of the retinal tear was rolled, and retinal detachment persisted. In OVD-treated eyes, the border of the retinal tear was indistinct, and the defect area was significantly decreased. These results show that application of an OVD effectively seals retinal tears and eliminates retinal detachments.
