Validating and troubleshooting ocular in vitro toxicology tests

Poly(2-hydroxyethyl methacrylate)-quercetin Conjugate as Biomaterial in Ophthalmology: An "ab initio" Study

A novel polymeric material with antioxidant properties and suitable for ophthalmic application was synthesized by free radical grafting reaction between 2-hydroxyethyl methacrylate and quercetin. The presence of quercetin in the polymeric chain was confirmed by FT-IR and UV-Vis analyses, while an estimation of the amount of quercetin bound per gram of polymer was obtained by the Folin-Ciocalteu assay. The conjugate shows high biocompatibility (HET-CAM assay) and antioxidant and anti-inflammatory properties which were extensively investigated by specific in vitro tests.

Antioxidant multi-walled carbon nanotubes by free radical grafting of gallic acid: new materials for biomedical applications

OBJECTIVES

To prove the possibility of covalently functionalizing multi-walled carbon nanotubes (CNTs) by free radical grafting of gallic acid on their surface with the subsequent synthesis of materials with improved biological properties evaluated by specific in-vitro assays.

METHODS

Antioxidant CNTs were synthesized by radical grafting of gallic acid onto pristine CNTs. The synthesis of carbon nanotubes was carried out in a fixed-bed reactor and, after the removal of the amorphous carbon, the grafting process was performed. The obtained materials were characterized by fluorescence and Fourier transform infrared spectroscopy (FT-IR) analyses. After assessment of the biocompatibility and determination of the disposable phenolic group content, the antioxidant properties were evaluated in terms of total antioxidant activity and scavenger ability against 2,2'-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl and peroxyl radicals. Finally the inhibition activity on acetylcholinesterase was evaluated.

KEY FINDINGS

  The covalent functionalization of CNTs with gallic acid was confirmed and the amount of gallic acid bound per g of CNTs was found to be 2.1±0.2 mg. Good antioxidant and scavenging properties were recorded in the functionalized CNTs, which were found to be able to inhibit the acetylcholinesterase with potential improved activity for biomedical and pharmaceutical applications.

CONCLUSIONS

For the first time, a free radical grafting procedure was proposed as a synthetic approach for the covalent functionalization of CNTs with an antioxidant polyphenol.

Plastic compressed collagen as a biomimetic substrate for human limbal epithelial cell culture

We describe, for the first time, the use of cellular plastic compressed collagen as a substrate for human limbal epithelial cell expansion and stratification. The characteristics of expanded limbal epithelial cells on either acellular collagen constructs or those containing human limbal fibroblasts were compared to a human central cornea control. After compression, human fibroblasts in collagen constructs remained viable and limbal epithelial cells were successfully expanded on the surface. After airlifting, a multilayered epithelium formed with epithelial cell morphology very similar to that of cells in the central cornea. Immunochemical staining revealed expression of basement membrane proteins and differentiated epithelial cell markers found in native central cornea. Ultrastructural analysis revealed cells on collagen constructs had many features similar to central cornea, including polygonal, tightly opposed surface epithelial cells with microvilli and numerous desmosomes at cell-cell junctions. Taken together, these data demonstrate that plastic compressed collagen constructs can form the basis of a biomimetic tissue model for in vitro testing and could potentially provide a suitable alternative to amniotic membrane as a substrate for limbal epithelial cell transplantation.

Troubleshooting pharmacological and toxicological methods

The majority of articles published in J Pharmacol Tox Methods describe new approaches, or modifications to those established (Curtis, 2006). However, even established methods have their limitations. It is part of the practice of research to troubleshoot: to identify methodological weaknesses and correct them. This process of troubleshooting is rarely acknowledged in research. The present issue of J Pharmacol Tox Methods draws on the expertise of the editorial board and their network of colleagues around the world to highlight how to troubleshoot the methods they use. We hope that the articles published herein with not only help those in the field to improve their research, but will also stimulate the community to feel more comfortable with the idea that improving established methods - and publishing the results - is a valuable part of the process. Now, and in the future, the journal will give its support and encouragement to the community to submit for publication papers that identify how to troubleshoot the methods they use.