These results indicate that using cultured HCECs and functional biomaterials, PNIPAAm and gelatin, an effective cell sheet-based therapy can be developed for the treatment of corneal endothelium deficiency.

IntroductionDry-eye syndrome (DES) is a general eye disease. Eye drops are the common ophthalmological medication. However, the ocular barrier makes it difficult to attain high drug bioavailability. Nanomedicine is a promising alternative treatment for ocular diseases and may increase drug content in the affected eye.MethodsTo explore this potential, we constructed nanoparticles (NPs) containing an anti-inflammatory agent for DES treatment. The NPs were made of gelatin–epigallocatechin gallate (EGCG) with surface decoration by hyaluronic acid (HA) and designated “GEH”. The particle size, surface charge, and morphology were evaluated. The in vitro biocompatibility and anti-inflammation effect of nanoparticles were assayed via culturing with human corneal epithelium cells (HCECs) and in vivo therapeutic effect was examined in a DES rabbit’s model.ResultsThe synthesized GEH NPs had a diameter of approximately 250 nm and were positively charged. A coculture experiment revealed that 20 µg/mL GEH was not cytotoxic to HCECs and that an EGCG concentration of 0.2 µg/mL downregulated the gene expression of IL1B and IL6 in inflamed HCECs. Large amounts of GEH NPs accumulated in the cytoplasm of HCECs and the ocular surfaces of rats and rabbits, indicating the advantage of GEH NPs for ocular delivery of medication. Twice-daily topical treatment with GEH NPs was performed in a rabbit model of DES. The ocular surface of GEH-treated rabbits displayed normal corneal architecture with no notable changes in inflammatory cytokine levels in the cornea lysate. The treatment improved associated clinical signs, such as tear secretion, and fluorescein staining recovered.ConclusionWe successfully produced GEH NPs with high affinity for HCECs and animal eyes. The treatment can be delivered as eye drops, which retain the drug on the ocular surface for a longer time. Ocular inflammation was effectively inhibited in DES rabbits. Therefore, GEH NPs are potentially valuable as a new therapeutic agent delivered in eye drops for treating DES.

Cell transplantation strategies usually involve the use of supporting carrier materials because of the soft and fragile nature of these grafts. In this work, a cell-adhesive gelatin hydrogel carrier was fabricated to deliver cultivated human corneal endothelial cell (HCEC) sheets, which were harvested from thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted culture surfaces. The carrier disks, consisting of gelatins with a different isoelectric point (IEP = 5.0 and 9.0) and a molecular weight (MW) ranging from 3 to 100 kDa, were subjected to 16.6 kGy gamma irradiation for sterilization. The effect of IEP and MW of the raw gelatins (i.e., before irradiation) on the functionality of sterilized disks was studied by determinations of mechanical property, water content, dissolution degree, and cytocompatibility. Irrespective of the IEP of raw gelatin, hydrogel disks prepared with high MW (100 kDa) exhibited a greater tensile strength, lower water content, and slower dissolution rate than those made of low MW gelatin (8 and 3 kDa). From the investigation of cellular responses to the disks, the negatively charged gelatin (IEP = 5.0) groups were more cytocompatible when compared with their positively charged counterparts (IEP = 9.0) at the same MW (100 kDa). Additionally, in the negatively charged gelatin groups, only a slight increase in pro-inflammatory cytokine expression was observed with increasing MW of gelatin from 3 to 100 kDa. It is concluded that the gamma-sterilized hydrogel disks made from raw gelatins (IEP = 5.0, MW = 100 kDa) with appropriate dissolution degree and acceptable cytocompatibility are capable of providing stable mechanical support, making these carriers promising candidates for intraocular delivery of cultivated HCEC sheets.

Dry eye disease (DED) has become common on a global scale in recent years. There is a wide prevalence of DED in different countries based on various ethnicities and environment. DED is a multifactorial ocular disorder. In addition to advanced age and gender, such factors as living at high altitude, smoking, pterygium, prolonged use of consumer electronics or overingesting of caffeine or multivitamins are considered to be the major risk factors of DED. We report the DED epidemiology in Taiwan firstly in this article. According to the pathophysiological factors and changes inthe composition of the tear film in DED, it can be categorized into several subtypes, including lipid anomaly dry eye, aqueous tear deficiency, allergic and toxic dry eye among others. Each subtype has its own cause and disease management; therefore, it is important for ophthalmologists to identify the type through literature review and investigation. The management of DED, relies not only on traditional medications such as artificial tears, gels and ointments, but also newer treatment options such as acupuncture, SYL1001, and nanomedicine therapy. We also conducted a comprehensive literature review including common subtypes and treatment of DED. Clearly, more clinical trials are needed to assess the efficacy and safety of the various treatments and common subtypes of DED.

To develop an effective ocular drug delivery carrier, we prepared two different charged gelatin nanoparticles (GPs) and evaluated particle size, surface charge, and morphology. The in vitro biocompatibility of GPs was assessed using human corneal epithelium (HCE) cells and in vivo safety by administering them as eye drops to New Zealand rabbits. The GPs prepared using type A gelatin were positively charged (GP(+), +33 mV; size, 180.6 ± 45.7 nm). Water-soluble tetrazolium salt (WST)-1 assay showed that both GPs were nontoxic to HCE cells. The fluorescence intensity of HCE cells cultured with cationic GPs conjugated with a fluorescent dye was higher than that of the anionic GP-treated HCE cells. In vivo examination showed no serious irritation to the rabbit eyes. Furthermore, corneal thickness and ocular pressure in the eyes of the treated rabbits were similar to those in the eyes of normal rabbits. Microscopic examination of corneal cryosections showed widely distributed fluorescent nanocarriers, from the anterior to the posterior part of the cornea of the GP(+) group, and higher fluorescence intensity in the GP(+) group was also observed. In conclusion, GPs as cationic colloidal carriers were efficiently adsorbed on the negatively charged cornea without irritating the eyes of the rabbits and can be retained in the cornea for a longer time. Thus, GPs(+) have a great potential as vehicles for ocular drug delivery.

Fourier-transform infrared (FTIR) microspectroscopy combining with attenuated total reflection (ATR) microsampling technique and micro-Raman spectrophotometer were used to detect the deposited materials on the surface of acrylic hydrogel intraocular lens (IOL) with or without ocular implantation. Surface morphology and the interface of this IOL were further examined by a confocal laser scanning microscope. The brand-new IOL exhibited a very smooth, transparent and featureless surface, but the explanted IOL had an irregular cerebriform-like opaque appearance. Both FTIR/ATR and Raman microspectroscopic analyses showed the deposits on the surface of acrylic hydrogel IOL after ocular implantation to consist of octacalcium phosphate (OCP) and Type B carbonated apatites, leading to the opalescence of acrylic hydrogel IOL. Both vibrational microspectroscopic examinations also confirmed the mineralization still in progress on the surface of acrylic hydrogel IOL after ocular implantation for 2 years.

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