Osteogenesis and

Cheng SL, Shao JS, Charlton-Kachigian N, Loewy AP, and Towler DA (2003) Msx2 promotes osteogenesis and suppresses adipogenic differentiation of multipotent mesenchymal progenitors. J. Biol. Chem. 278 45969-45977. 

Muzzarelli et al. (2000) described a method for coating prosthetic articles with chitosan-oxychitin. Plates of titanium (Ti) and its alloys were plasma sprayed with hydroxyapatite and glass layers, and subsequently a chitosan coat was deposited on the plasma-sprayed layers using chitosan acetate. These layers were treated with 6-oxychitin to form a polyelectrolytic complex. This complex was optionally contacted with l-ethyl-3-(3-dimethylami-nopropyl) carbodiimide at 4°C for 2 hours to form amide links between the two polysaccharides, or acetylation with acetic anhydride in methanol to obtain a chitin film. In all cases, the modified coats were insoluble, uniformly flat, and smooth. Prosthetic materials coated with chitosan-oxychitin were capable of provoking colonization by cells, osteogenesis, and osteointegration. 

After intravenous injection in patients, Tc-(Sn)-pyrophosphate accumulates in regions of active osteogenesis, and also in injured myocardium, mainly in necrotic tissue (Buja et al. 1977). Uptake in infarcted myocardium in experimental model (dog) was reported as 4.4% injected dose (ID)/g, compared with 0.31% in normal myocardial tissue (Bevan et al. (1980). 

Similar to the situation with 2D membranes, the basic molecular characteristics of chitosan such as DD also show great influence on the ability of chitosan scaffolds to modulate stem cell behavior. The chitosan scaffolds with a high DD can maintain the viability and pluripotency of buffalo embryonic stem-like (ES-Uke) cells [15]. However, the cell behavior on 2D and 3D environments are quite different. Comparison of MSC behavior in both 2D plates and chitosan/gelatin/chondroitin scaffolds demonstrates that the 3D microenviromnent can enhance osteogenesis and maintain the viability of cells [161]. The research by Altman et al. [162] found that the apparent elastic modulus and cytoskeleton F-actin fiber density were higher for ADSCs seeded in 3D sflk fibroin/chitosan scaffolds than on 2D glass plates (Fig. 13). 

Gonda Y, Shibata Y, Okuda T, Kawachi G, Kamitakahara M, Murayama H, et al. Stimulatory effect of hydrothermally synthesized biodegradable hydroxyapatite grannies on osteogenesis and direct association with osteoclasts. Biomateiials 2009 30 4390-4400. 

Another demonstrative example is the layered-scaffolds of BMP-incorporated HA nanocomposite for inducing osteogenesis and subsequent bone regeneration. A type of HA/chitosan/PAA nanocomposite, fabricated by the LbL technique introduced in... 

Batouli, S., Miura, M., Brahtm, J., Tsutsui, T, Fisher, L., Gronthos, S., Robey, RG., Shi, S., 2003. Comparison of stem-cell-mediated osteogenesis and dentinogenesis. J. Dental Res. 82,976-981. 

There are three main types of bone cells, known as osteoclasts, osteoblasts and osteocytes. Osteoblasts are associated with the formation of the web of collagen fibres, within which the crystallisation of hydroxyapatite eventnaUy occurs (osteogenesis), and osteoclasts are connected with bone removing (resorption) processes. Osteocytes are classified as bone-maintaining. 

For instance, from in vitro and in vivo results, it is hypothesized that low porosity could improve osteogenesis and encourage cell aggregation, but lead to less-oriented structure porosity and neovascularization limitations. 

Unlike any other biomaterial, nacre from the pearl oyster, Pinctada maxima, is able to induce osteogenesis and bone formation from latent osteoprogenitors along an endochondral pathway, consisting of a cartilage tissue intermediary phase (Lopez et al., 1992). 

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