Xing-Hua Wang

Bio: Xing-Hua Wang is an academic researcher from Huazhong University of Science and Technology. The author has contributed to research in topics: Posterior segment of eyeball & Corneal pachymetry. The author has an hindex of 3, co-authored 4 publications receiving 22 citations.

Evaluation of RGD peptide hydrogel in the posterior segment of the rabbit eye

Abstract: The aim of this study was to evaluate the biocompatibility and biodegradability of RGD peptide hydrogel in the posterior segment of the eye as a biomaterial potentially useful for sustained drug delivery systems RGD peptide hydrogel was injected into the vitreous cavity and suprachoroidal space of rabbit eyes Clinical follow-up and histological observation were performed up to four weeks The biodegradability was also evaluated by the lifetime of the hydrogel which was defined by ophthalmoscopic observation or ultrasonography The results showed that RGD peptide hydrogel was well tolerated in the vitreous cavity and suprachoroidal space, and disappeared from the injection sites progressively As for suprachoroidal injection, the hydrogel was clearly identified by ultrasound echography and was confirmed innoxious to the retinal vessels by fluorescein angiography Histological observations showed that the structures of retina, choroid and other tissues around the injection site remained normal after the i

Retinal Metabolic Changes in an Experimental Model of Optic Nerve Transection by Ex Vivo 1H Magnetic Resonance Spectroscopy

Abstract: This study aims to investigate the retinal metabolic processes in a rat axotomy model. Retinal metabolic changes in optic nerve transection (ONT) rat model were analyzed by H-1 magnetic resonance spectroscopy (H-1-MRS). Retinal ganglion cells (RGCs) densities were assessed from retinal whole mounts. The retina was stained immunohistochemically with glial fibrillary acidic protein (GFAP). The results showed that the retina in ONT rats had significantly decreased concentrations of gamma-aminobutyric acid (GABA), N-acetylaspartate (NAA), taurine (Tau), creatine (Cr) and increased concentrations of alanine (Ala) compared with control. Examination of glutamate (Glu), glutamine (Gln) and Glx (Glu + Gln) concentrations disclosed no significant differences. The mean density of RGCs reduced from 2,249 +/- A 87 cells/mm(2) in control group to 320 +/- A 56 cells/mm(2) in ONT group. GFAP immunoreactivity was markedly higher in ONT group than that in control group. The retinal metabolism after ONT was associated with neurotransmitter recycling/production perturbation, as well as other metabolic disequilibrium.

Metabolic profile of visual cortex in diabetic rats measured with in vivo proton MRS

Abstract: The purpose of the present study was to characterize the metabolic profile of the visual cortex in streptozotocin-induced Type 1 diabetic rats by means of in vivo proton MRS. Several metabolite concentration ratios in the visual cortex were calculated. In addition, postmortem histologic analyses for retinal ganglion cell (RGC) loss, optic nerve injury and visual cortex alterations were monitored. The results showed that diabetes induced several changes in visual cortex metabolites, such as reduced N-acetylaspartate, glutamate, γ-aminobutyric acid, taurine and choline-containing compound levels. Nevertheless, myo-inositol levels increased significantly as compared with controls. Remarkable RGC loss and optic nerve degeneration were observed by morphological analysis. Moreover, the results showed significant neuronal loss and glial activation in the visual cortex. These findings indicated that, besides vascular abnormalities, neuronal loss and degeneration in the visual pathway were induced due to disrupted glucose homeostasis in diabetes. Metabolic or functional abnormalities were induced in cerebral neurons of the visual cortex by diabetes.

Self-Assembling Peptide Nanofibrous Hydrogel as a Versatile Drug Delivery Platform

Abstract: Molecular hydrogels have been widely explored in various biomedical applications, such as cell culture, tissue engineering and drug delivery. Peptide-based hydrogel nanoparticles represent a promising alternative to current drug delivery approaches and cell carriers for tissue engineering, due to their encapsulation stability, water solubility and biocompatibility. This review focuses on recent advances in the use of self-assembling peptide nanogels for applications in drug delivery. We firstly introduce a self-assembly mechanism for small molecules used in the peptide hydrogel, and then describe recent methods for controlling the assembly of molecular hydrogelations. A particular emphasis is placed on recent advances in the use of different types of peptide hydrogels as drug delivery carriers. Lastly, the current challenges and future perspectives for self-assembling peptide hydrogels in drug delivery applications are discussed.

Covalently Crosslinked Hydrogels via Step-Growth Reactions: Crosslinking Chemistries, Polymers, and Clinical Impact.

Abstract: Hydrogels are an important class of biomaterials with the unique property of high-water content in a crosslinked polymer network. In particular, chemically crosslinked hydrogels have made a great clinical impact in past years because of their desirable mechanical properties and tunability of structural and chemical properties. Various polymers and step-growth crosslinking chemistries are harnessed for fabricating such covalently crosslinked hydrogels for translational research. However, selecting appropriate crosslinking chemistries and polymers for the intended clinical application is time-consuming and challenging. It requires the integration of polymer chemistry knowledge with thoughtful crosslinking reaction design. This task becomes even more challenging when other factors such as the biological mechanisms of the pathology, practical administration routes, and regulatory requirements add additional constraints. In this review, key features of crosslinking chemistries and polymers commonly used for preparing translatable hydrogels are outlined and their performance in biological systems is summarized. The examples of effective polymer/crosslinking chemistry combinations that have yielded clinically approved hydrogel products are specifically highlighted. These hydrogel design parameters in the context of the regulatory process and clinical translation barriers, providing a guideline for the rational selection of polymer/crosslinking chemistry combinations to construct hydrogels with high translational potential are further considered.

Clearance Kinetics and Clearance Routes of Molecules From the Suprachoroidal Space After Microneedle Injection.

Abstract: Purpose To determine clearance kinetics and routes of clearance of molecules from the suprachoroidal space (SCS) of live New Zealand White rabbits. Methods Suprachoroidal space collapse rate and pressure changes after microneedle injection into SCS were determined. Fluorescent fundus images were acquired to determine clearance rates of molecules ranging in size from 332 Da to 2 MDa. Microneedle injections of fluorescein were performed, and samples were taken from various sites over time to determine amount of fluorescein exiting the eye. Clearance transport was modeled theoretically and compared with experimental data. Results After injection, pressures in SCS and vitreous humor spiked and returned to baseline within 20 minutes; there was no difference between these two pressures. Suprachoroidal space collapse occurred within 40 minutes. One hour after fluorescein injection, 46% of fluorescein was still present in the eye, 15% had transported across sclera, 6% had been cleared by choroidal vasculature, and 4% had exited via leakage pathways. Characteristic clearance time increased in proportion with molecular radius, but total clearance of 2 MDa FITC-dextran was significantly slower (21 days) than smaller molecules. These data generally agreed with predictions from a theoretical model of molecular transport. Conclusions Guided by experimental data in the context of model predictions, molecular clearance from SCS occurred in three regimes: (1) on a time scale of approximately 10 minutes, fluid and molecules exited SCS by diffusion into sclera and choroid, and by pressure-driven reflux via transscleral leakage sites; (2) in approximately 1 hour, molecules cleared from choroid by blood flow; and (3) in 1 to 10 hours, molecules cleared from sclera by diffusion and convection.