In addition to good mechanical properties needed for three-dimensional tissue engineering, the combination of alginate dialdehyde, gelatin and nano-scaled bioactive glass (45S5) is supposed to combine excellent cellular adhesion, proliferation and differentiation properties, good biocompatibility and predictable degradation rates. The goal of this study was to evaluate thein vitro and in vivo biocompatibility as a first step on the way to its use as a scaffold in bone tissue engineering. In vitro evaluation showed good cell adherence and proliferation of bone marrow derived mesenchymal stem cells seeded on covalently crosslinked alginate dialdehyde-gelatin (ADA-GEL) hydrogel films with and without 0.1% nano-Bioglass®(nBG). Lactate dehydrogenase (LDH)- and mitochondrial activity significantly increased in both ADA-GEL and ADA-GEL-nBG groups compared to alginate. However, addition of 0.1% nBG seemed to have slight cytotoxic effect compared to ADA-GEL. In vivo implantation did not produce a significant inflammatory reaction, and ongoing degradation could be seen after four weeks. Ongoing vascularization was detected after four weeks. The good biocompatibility encourages future studies using ADA-GEL and nBG for bone tissue engineering application.

Collagen I is the major fibrous extracellular component of bone responsible for its ultimate tensile strength. In tissue engineering, one of the most important challenges for tissue formation is to get cells interconnected via a strong and functional extracellular matrix (ECM), mimicking as closely as possible the natural ECM geometry. Still missing in tissue engineering are: (a) a versatile, high-resolution and non-invasive approach to evaluate and quantify different aspects of ECM development within engineered biomimetic scaffolds online; and (b) deeper insights into the mechanism whereby cellular matrix production is enhanced in 3D cell-scaffold composites, putatively via enhanced focal adhesion linkage, over the 2D setting. In this study, we developed sensitive morphometric detection methods for collagen I-producing and bone-forming mesenchymal stem cells (MSCs), based on multiphoton second harmonic generation (SHG) microscopy, and used those techniques to compare collagen I production capabilities in 2D- and 3D-arranged cells. We found that stimulating cells with 1% serum in the presence of ascorbic acid is superior to other medium conditions tested, including classical osteogenic medium. In contrast to conventional 2D culture, having MSCs packed closely in a 3D environment presumably stimulates cells to produce strong and complex collagen I networks with defined network structures (visible in SHG images) and improves collagen production. Copyright © 2015 John Wiley & Sons, Ltd.

Abstracteffects of 3D scaffolds made from 45S5 bioactive glass (BG) doped with 1 wt. % copper ions in the arteriovenous loop model of the rat.Materials and Methods: An arteriovenous loop was built in the groin of 10 rats and inserted in 1% copper doped 45S5 BG scaffolds and fibrin. The scaffold and the AV loop were inserted in Teflon isolation chambers and explanted 3 weeks after implantation. Afterwards the scaffolds were analyzed by Micro-CT and histology regarding vascularization. Results were compared to plain 45S5 BG-based scaffolds from a previous study.Results: Micro-CT and histological evaluation showed consistent vascularization of the constructs. A tendency towards an increased vascularization in the copper doped BG group compared to plain BG constructs could be observed. However, therewas no significant difference in statistical analysis between both groups.Conclusions: This study shows results that support an increased angiogenetic effect of 1% copper doped 45S5 BG compared to regular 45S5 BG scaffolds in the rat arteriovenous loop model although these tendencies are not backed by statistical evidence. Maybe higher copper doses could lead to a statistically significant angiogenetic effect.