Control of stem cell differentiation by using extrinsic photobiomodulation in conjunction with cell adhesion pattern.

The induction and direction of stem cell differentiation into needed cell phenotypes is the central pillar of tissue engineering for repairing damaged tissues or organs. Conventionally, a special recipe of chemical factors is formulated to achieve this purpose for each specific target cell type. In this work, it is demonstrated that the combination of extrinsic photobiomodulation and collagen-covered microislands could be used to induce differentiation of Wharton's jelly mesenchymal stem cells (WJ-MSCs) with the differentiation direction dictated by the specific island topography without use of chemical factors. Both neurogenic differentiation and adipogenic differentiation could be attained with a rate surpassing that using chemical factors. Application of this method to other cell types is possible by utilizing microislands with a pattern tailored particularly for each specific cell type, rendering it a versatile modality for initiating and guiding stem cell differentiation.

Modulated transdermal delivery of nonsteroidal anti-inflammatory drug by macroporous poly(vinyl alcohol)-graphene oxide nanocomposite films.

In this study, a facile, economically feasible, and scalable approach to fabricate macroporous poly(vinyl alcohol)-GO (PVA-GO) nanocomposite films with varying filler loadings was demonstrated. The nanocomposite films were prepared using a solvent casting process and employed as a diffusion layer for modulating the transdermal delivery of an anti-inflammatory drug (i.e., ketoprofen). The diffusion membrane was assembled in a three-layer structure with PVA/PVA-GO films between ketoprofen-loaded cellulose and cellulose acetate to mimic skin barrier. Through the incorporation of GO sheets into PVA matrix, the mass diffusion and drug release rate of ketoprofen could be modulated to attain a controlled-release system within period in comparison to that of neat PVA film, which showed more rapid release. It was observed that the dispersion level of GO sheets in the polymer matrix played a crucial role to slow the diffusion rate and drug release, where 3 wt% filler loading gave the slowest rate of release. The results from the present study shed light on the mechanism of and may provide guidelines for modulating drug release rates of NSAID in film-based delivery vehicles for transdermal delivery applications.