An electroactive alginate hydrogel nanocomposite reinforced by functionalized graphite nanofilaments for neural tissue engineering.

To address the need to biodegradable, electroactive conduits accelerating nerve regeneration, here we develop a nanocomposite hydrogel made of alginate reinforced by citric acid functionalized graphite nanofilaments. The green, simple functionalization enhances the nanofillers distribution and their biocompatibility, as verified using mesenchymal stem cells in vitro. The uniformly distributed nanofilaments raise mechanical stability of the nanocomposite hydrogel versus the neat one up to three times. Also, the nanofilaments enable electrical contact and intercellular signaling thereby stimulating their biological activity. In vitro studies proved the biocompatibility of the nanocomposite hydrogel whereon PC12 cells proliferate and spread evidently. In vivo tests also supported applicability of the nanocomposite hydrogel for implantation within body, and the samples showed no adverse reaction and no inflammatory responses after 14 days. Conclusively, the results certify that the developed electroactive nanocomposite hydrogel is able to stimulate nerve generation and could be confidently used as a nerve conduit material.

Formation of salivary acinar cell spheroids in vitro above a polyvinyl alcohol-coated surface.

Tissue engineering of salivary glands offers the potential for future use in the treatment of patients with salivary hypofunction. Biocompatible materials that promote acinar cell aggregation and function in vitro are an essential part of salivary gland tissue engineering. In this study, rat parotid acinar cells assembled into three-dimensional aggregates above the polyvinyl alcohol (PVA)-coated surface. These aggregates developed compact acinar cell spheroids resembling in vivo physiological condition, which were different from the traditional monolayered morphology in vitro. Cells remained viable and with better functional activity in response to acetylcholine in the spheroids and could form monolayered acinar cells when they were reinoculated on tissue culture polystyrene wells. To interpret the phenomenon further, we proposed that the formation of acinar cell spheroids on the PVA is mediated by a balance between two competing forces: the interactions of cell-PVA and cell-cell. This study demonstrated the formation of functional cell spheroids above a PVA-coated surface may provide an in vitro system for investigating cell behaviors for tissue engineering of artificial salivary gland.