Mucoadhesive Nanoparticles for Drug Delivery to the Anterior Eye.

While the use of topical drops for the delivery of drugs to the anterior of the eye is well accepted, it is far from efficient with as little as 5% of the drug instilled on the eye actually reaching the target tissue. The ability to prolong the residence time on the eye is desirable. Based on the acceptability of 2-hydroxyethyl methacrylate based polymers in contact lens applications, the current work focuses on the development of a poly(2-hydroxyethyl methacrylate (HEMA)) nanoparticle system. The particles were modified to allow for degradation and to permit mucoadhesion. Size and morphological analysis of the final polymer products showed that nano-sized, spherical particles were produced. FTIR spectra demonstrated that the nanoparticles comprised poly(HEMA) and that 3-(acrylamido)phenylboronic acid (3AAPBA), as a mucoadhesive, was successfully incorporated. Degradation of nanoparticles containing N,N'-bis(acryloyl)cystamine (BAC) after incubation with DL-dithiothreitol (DTT) was confirmed by a decrease in turbidity and through transmission electron microscopy (TEM). Nanoparticle mucoadhesion was shown through an in-vitro zeta potential analysis.

Single-Step Reactive Electrospinning of Cell-Loaded Nanofibrous Scaffolds as Ready-to-Use Tissue Patches.

A reactive electrospinning strategy is used to fabricate viable and proliferative cell-loaded nanofibrous hydrogel scaffolds in a single step using an all-aqueous approach. In situ gelling and degradable hydrazone-cross-linked poly(oligo ethylene glycol methacrylate)-based hydrogel nanofibrous networks can be produced directly in the presence of cells to support long-term cell viability, adhesion, and proliferation, in contrast to bulk hydrogels of the same composition. Furthermore, the capacity of the gel nanofibers to retain bound water maintains this high cell viability and proliferative capacity following a freeze/thaw cycle without requiring any cryoprotectant additives, ideal properties for ready-to-use functional tissue patches.

Injectable and Degradable Poly(Oligoethylene glycol methacrylate) Hydrogels with Tunable Charge Densities as Adhesive Peptide-Free Cell Scaffolds.

Injectable, dual-responsive, and degradable poly(oligo ethylene glycol methacrylate) (POEGMA) hydrogels are demonstrated to offer potential for cell delivery. Charged groups were incorporated into hydrazide and aldehyde-functionalized thermoresponsive POEGMA gel precursor polymers via the copolymerization of N,N'-dimethylaminoethyl methacrylate (DMAEMA) or acrylic acid (AA) to create dual-temperature/pH-responsive in situ gelling hydrogels that can be injected via narrow gauge needles. The incorporation of charge significantly broadens the swelling, degradation, and rheological profiles achievable with injectable POEGMA hydrogels without significantly increasing nonspecific protein adsorption or chronic inflammatory responses following in vivo subcutaneous injection. However, significantly different cell responses are observed upon charge incorporation, with charged gels significantly improving 3T3 mouse fibroblast cell adhesion in 2D and successfully delivering viable and proliferating ARPE-19 human retinal epithelial cells via an "all-synthetic" matrix that does not require the incorporation of cell-adhesive peptides.

An Injectable Hydrogel Prepared Using a PEG/Vitamin E Copolymer Facilitating Aqueous-Driven Gelation.

Hydrogels have been widely explored for biomedical applications, with injectable hydrogels being of particular interest for their ability to precisely deliver drugs and cells to targets. Although these hydrogels have demonstrated satisfactory properties in many cases, challenges still remain for commercialization. In this paper, we describe a simple injectable hydrogel based on poly(ethylene glycol) (PEG) and a vitamin E (Ve) methacrylate copolymer prepared via simple free radical polymerization and delivered in a solution of low molecular weight PEG and Ve as the solvent instead of water. The hydrogel formed immediately in an aqueous environment with a controllable gelation time. The driving force for gelation is attributed to the self-assembly of hydrophobic Ve residues upon exposure to water to form a physically cross-linked polymer network via polymer chain rearrangement and subsequent phase separation, a spontaneous process with water uptake. The hydrogels can be customized to give the desired water content, mechanical strength, and drug release kinetics simply by formulating the PEGMA-co-Ve polymer with an appropriate solvent mixture or by varying the molecular weight of the polymer. The hydrogels exhibited no significant cytotoxicity in vitro using fibroblasts and good tissue compatibility in the eye and when injected subcutaneously. These polymers thus have the potential to be used in a variety of applications where injection of a drug or cell containing depot would be desirable.

A Retrospective Evaluation of Injuries to Australian Urban Firefighters (2003 to 2012): Injury Types, Locations, and Causal Mechanisms.

OBJECTIVE: Benchmark data were sought for evaluating injury trends within Australian firefighters. METHODS: Work-related injury data from Australia's largest urban fire and rescue organization were analyzed (2003 to 2012), with an emphasis on classification (occurrence, mechanism, agency, nature, and location) and demographic details. RESULTS: Firefighters were injured on 6997 occasions (177 injuries per annum per 1000 full-time employees). The largest causal mechanism was muscular stress (74 injuries per 1000 full-time employees annually), with 62.1% of those incidents involving materials handling and slips, trips, and falls. No single mechanism could explain more than 20% of the injuries. The principal injury type involved sprains and strains. The most commonly injured sites were the knee, lower back, shoulder, and ankle. CONCLUSIONS: These observations provide a basis for intervention strategies that target sprains and strains associated with materials handling and slips, trips, and falls.

Beyond decoding: phonological processing during silent reading in beginning readers.

In this experiment, the extent to which beginning readers process phonology during lexical identification in silent sentence reading was investigated. The eye movements of children aged seven to nine years and adults were recorded as they read sentences containing either a correctly spelled target word (e.g., girl), a pseudohomophone (e.g., gerl), or a spelling control (e.g., garl). Both children and adults showed a benefit from the valid phonology of the pseudohomophone, compared to the spelling control during reading. This indicates that children as young as seven years old exhibit relatively skilled phonological processing during reading, despite having moved past the use of overt phonological decoding strategies. In addition, in comparison to adults, children's lexical processing was more disrupted by the presence of spelling errors, suggesting a developmental change in the relative dependence upon phonological and orthographic processing in lexical identification during silent sentence reading.

Fibronectin-Alginate microcapsules improve cell viability and protein secretion of encapsulated Factor IX-engineered human mesenchymal stromal cells.

Continuous delivery of proteins by engineered cells encapsu-lated in biocompatible polymeric microcapsules is of considerable therapeutic potential. However, this technology has not lived up to expectations due to inadequate cell--matrix interactions and subsequent cell death. In this study we hypoth-esize that the presence of fibronectin in an alginate matrix may enhance the viability and functionality of encapsulated human cord blood-derived mesenchymal stromal cells (MSCs) expressing the human Factor IX (FIX) gene. MSCs were encapsulated in alginate-PLL microcapsules containing 10, 100, or 500 µg/ml fibronectin to ameliorate cell survival. MSCs in microcapsules with 100 and 500 µg/ml fibronectin demonstrated improved cell viability and proliferation and higher FIX secretion compared to MSCs in non-supplemented microcapsules. In contrast, 10 µg/ml fibronectin did not significantly affect the viability and protein secretion from the encapsulated cells. Differentiation studies demonstrated osteogenic (but not chondrogenic or adipogenic) differentiation capability and efficient FIX secretion of the enclosed MSCs in the fibronectin-alginate suspension culture. Thus, the use of recombinant MSCs encapsulated in fibronectin-alginate microcapsules in basal or osteogenic cultures may be of practical use in the treatment of hemophilia B.

Sustained expression of coagulation factor IX by modified cord blood-derived mesenchymal stromal cells.

BACKGROUND: Hemophilia B patients are subject to frequent and spontaneous bleeding caused by a deficiency of clotting factor IX (FIX). Mesenchymal stromal cells (MSCs) have been used in cellular therapies as a result of their immunomodulatory properties, the ability to home to sites of injury and their amenability to various ex vivo modifications, including lentiviral-mediated gene transfer. METHODS: MSCs were isolated from human umbilical cord blood and differentiated into adipogenic, chondrogenic and osteogenic lineages. A lentiviral DNA vector containing the human FIX gene was generated using traditional restriction enzyme digest and ligation techniques to generate viable replication-incompetent lentiviral particles that were used to transduce MSCs. Quantitative measurement of FIX expression was conducted using an enzyme-linked immunosorbent assay. RESULTS: The over-expression of FIX was sustained in vitro at levels > 4 µg/10(6) cells/24 h and FIX coagulant activity was > 2.5 mIU/10(6) cells/24 h for the 6-week duration of study. Lentiviral modification of cells with a multiplicity of infection of 10 did not adversely affect the potential of cord blood (CB) MSCs to differentiate to adipocytes, chondrocytes and osteoblastic cells, and the expression of functional FIX was sustained after differentiation and was similar to that in nondifferentiated cells. CONCLUSIONS: Modification of human CB MSCs with a lentiviral vector resulted in sustained high FIX expression in vitro after differentiation to adipogenic, chondrogenic and osteoblastic cells. These modified MSCs could have applications in cellular therapies for hemophilia B.

Cell-matrix Interactions of Factor IX (FIX)-engineered human mesenchymal stromal cells encapsulated in RGD-alginate vs. fibrinogen-alginate microcapsules.

The success of cell microencapsulation technology in tissue engineering and protein delivery applications depends on the viability and functionality of the encapsulated cells, which in turn are dependent upon cell/matrix interactions. In this work, we compared the viability of cord blood-derived mesenchymal stromal cells (CB MSCs), engineered to secrete factor IX (FIX) for hemophilia treatment, and encapsulated in arginine-glycine-aspartate (RGD)-alginate versus fibrinogen-alginate microcapsules. We evaluated the effect of the biomimetic matrix on cell attachment, proliferation, and secretion of FIX. Compared with nonsupplemented alginate matrix, RGD-alginate significantly enhanced the viability of the encapsulated MSCs. Further, cells in RGD-alginate displayed distinct attachment morphology, thus suggesting that RGD-alginate can potentially be used for the encapsulation of MSCs in tissue engineering applications that require enhanced cell attachment and viability. However, our data also showed that RGD-alginate microcapsules, in contrast to fibrinogen-alginate microcapsules, did not significantly improve cell proliferation of or FIX secretion by encapsulated MSCs. Our findings suggest that evidence of cell attachment alone may not accurately predict the functionality of cells in biomimetic microcapsules.

Encapsulation of factor IX-engineered mesenchymal stem cells in fibrinogen-alginate microcapsules enhances their viability and transgene secretion.

Cell microencapsulation holds significant promise as a strategy for cellular therapies; however, inadequate survival and functionality of the enclosed cells limit its application in hemophilia treatment. Here, we evaluated the use of alginate-based microcapsules to enhance the viability and transgene secretion of human cord blood-derived mesenchymal stem cells in three-dimensional cultures. Given the positive effects of extracellular matrix molecules on mesenchymal stem cell growth, we tested whether fibrinogen-supplemented alginate microcapsules can improve the efficiency of encapsulated factor IX-engineered mesenchymal stem cells as a treatment of hemophilia B. We found that fibrinogen-supplemented alginate microcapsules (a) significantly enhanced the viability and proliferation of factor IX-engineered mesenchymal stem cells and (b) increased factor IX secretion by mesenchymal stem cells compared to mesenchymal stem cells in nonsupplemented microcapsules. Moreover, we observed the osteogenic, but not chondrogenic or adipogenic, differentiation capability of factor IX-engineered cord blood mesenchymal stem cells and their efficient factor IX secretion while encapsulated in fibrinogen-supplemented alginate microcapsules. Thus, the use of engineered mesenchymal stem cells encapsulated in fibrinogen-modified microcapsules may have potential application in the treatment of hemophilia or other protein deficiency diseases.