Osteoblastic differentiation under controlled bioactive ion release by silica and titania doped sodium-free calcium phosphate-based glass.

Sodium-free phosphate-based glasses (PGs) doped with both SiO2 and TiO2 (50P2O5-40CaO-xSiO2-(10-x)TiO2, where x=10, 7, 5, 3, and 0mol%) were developed and characterised for controlled ion release applications in bone tissue engineering. Substituting SiO2 with TiO2 directly increased PG density and glass transition temperature, indicating a cross-linking effect of Ti on the glass network which was reflected by significantly reduced degradation rates in an aqueous environment. X-ray diffraction confirmed the presence of Ti(P2O7) in crystallised TiO2-containing PGs, and nuclear magnetic resonance showed an increase in Q(1) phosphate species with increasing TiO2 content.

Effect of chitosan incorporation and scaffold geometry on chondrocyte function in dense collagen type I hydrogels.

Tissue engineering approaches for articular cartilage (AC) repair using collagen type I (Coll)-based hydrogels are limited by their low collagen fibril density (CFD; <0.5 wt%) and their poor capacity to support chondrocyte differentiation. Chitosan (CTS) is a well-characterized polysaccharide that mimics the glycosaminoglycans (GAGs) present in native AC extracellular matrix and exhibits chondroprotective properties.

Factor XIIIA transglutaminase expression and secretion by osteoblasts is regulated by extracellular matrix collagen and the MAP kinase signaling pathway.

Osteoblast differentiation is regulated by the presence of collagen type I (COL I) extracellular matrix (ECM). We have recently demonstrated that Factor XIIIA (FXIIIA) transglutaminase (TG) is required by osteoblasts for COL I secretion and extracellular deposition, and thus also for osteoblast differentiation. In this study we have further investigated the link between COL I and FXIIIA, and demonstrate that COL I matrix increases FXIIIA levels in osteoblast cultures and that FXIIIA is found as cellular (cFXIIIA) and extacellular matrix (ecmFXIIIA) forms.

Osteoid-mimicking dense collagen/chitosan hybrid gels.

Bone extracellular matrix (ECM) is a 3D network, composed of collagen type I and a number of other macromolecules, including glycosaminoglycans (GAGs), which stimulate signaling pathways that regulate osteoblast growth and differentiation. To model the ECM of bone for tissue regenerative approaches, dense collagen/chitosan (Coll/CTS) hybrid hydrogels were developed using different proportions of CTS to mimic GAG components of the ECM. MC3T3-E1 mouse calvaria preosteoblasts were seeded within plastically compressed Coll/CTS hydrogels with solid content approaching that of native bone osteoid.

An in vitro assessment of a cell-containing collagenous extracellular matrix-like scaffold for bone tissue engineering.

Extracellular matrix (ECM) consists of a complex mixture of macromolecules such as collagens, proteoglycans, glycoproteins, and elastic fibers. ECM is essential to preserving tissue architecture, signaling to cells, and regulating calcification in mineralized tissues. Osteoblasts in culture secrete and assemble an extensive ECM rich in type I collagen, and other noncollagenous proteins that can be mineralized.