Publication date: June 2017 Source:Biomaterials, Volume 129 Author(s): Gozde Eke, Naside Mangir, Nesrin Hasirci, Sheila MacNeil, Vasif Hasirci The aim of this study was to design a dermal substitute containing adipose derived stem cells (ADSC) that can be used to improve the regeneration of skin on difficult wound beds by stimulating rapid neovascularization. This was achieved by first synthesizing methacrylated gelatin (GelMA) and methacrylated hyaluronic acid (HAMA) precursors which could be stored at −80 oC after lyophilisation. Polymer precursors were then dissolved in media (in 15:1 ratio), ADSCs added together with the photoinitiator and crosslinked with 40 s of UV. Hydrogels degraded by 50% over 3 weeks in an in vitro environment. ADSC loaded hydrogels could be easily handled with forceps (compressive modulus was 6 kPa). Transparency of the gel would allow a full field-of-view of a wound site. The hydrogels provided a suitable microenvironment for ADSC proliferation as shown by the filopodia observed in confocal micrographs. In vivo studies demonstrated that stem cell loaded hydrogels increased vascularization by up to 3 fold compared to their cell free counterparts. In conclusion, GelMA/HAMA hydrogels loaded with ADSC showed the desired proliferative and angiogenic properties essential to promote angiogenesis for wound healing and improving survival of tissue engineered skin. Graphical abstract
Publication date: June 2017 Source:Biomaterials, Volume 129 Author(s): C. Boehler, C. Kleber, N. Martini, Y. Xie, I. Dryg, T. Stieglitz, U.G. Hofmann, M. Asplund Stable interconnection to neurons in vivo over long time-periods is critical for the success of future advanced neuroelectronic applications. The inevitable foreign body reaction towards implanted materials challenges the stability and an active intervention strategy would be desirable to treat inflammation locally. Here, we investigate whether controlled release of the anti-inflammatory drug Dexamethasone from flexible neural microelectrodes in the rat hippocampus has an impact on probe-tissue integration over 12 weeks of implantation. The drug was stored in a conducting polymer coating (PEDOT/Dex), selectively deposited on the electrode sites of neural probes, and released on weekly basis by applying a cyclic voltammetry signal in three electrode configuration in fully awake animals. Dex-functionalized probes provided stable recordings and impedance characteristics over the entire chronic study. Histological evaluation after 12 weeks of implantation revealed an overall low degree of inflammation around all flexible probes whereas electrodes exposed to active drug release protocols did have neurons closer to the electrode sites compared to controls. The combination of flexible probe technology with anti-inflammatory coatings accordingly offers a promising approach for enabling long-term stable neural interfaces.