In bone tissue engineering, bioglass coating of titanium (Ti) scaffolds has drawn attention as a method to improve osteointegration and implant fixation. In this in vitro study, bioactive glass layers with an approximate thickness of 1 microm were deposited at 200 degrees C onto a three-dimensional Ti-6Al-4V scaffold using a radio frequency (r.f.) magnetron sputtering system. After incubation with SAOS-2 human osteoblasts, in comparison with the uncoated scaffolds, the bioglass-coated scaffolds showed a twofold increase in cell proliferation (p < 0.05) up to 68.4 x 10(6), and enhanced the deposition of extracellular matrix components such as decorin, fibronectin, osteocalcin, osteonectin, osteopontin, and type-I and -III collagens (p < 0.05). Calcium deposition was twofold greater on the bioglass-coated scaffolds (p < 0.05). The immunofluorescence related to the preceding bone matrix proteins and calcium showed their colocalization to the cell-rich areas. Alkaline phosphatase activity increased twofold (p < 0.001) and its protein content was threefold higher with respect to the uncoated sample. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed upregulated transcription specific for type-I collagen and osteopontin (p < 0.001). All together, these results demonstrate that the bioglass coating of the three-dimensional Ti scaffolds by the r.f. magnetron sputtering technique determines an in vitro increase of the bone matrix elaboration and may potentially have a clinical benefit.
Degeneration of intervertebral discs is the most common cause of back pain. The first phase of this degenerative process involves the nucleus pulposus (NP). A rapid recovery of this structure can prevent further degradation of the annulus fibrosus. A new amidic derivative of alginate (AAA) was developed to obtain a polysaccharide possessing some of the physical-chemical properties of Hyal (i.e. viscosity) without losing the rigidity of the native alginate structure. The modified polysaccharide was crosslinked using 1.3 diaminopropane as crosslinking agent. The hydrogel obtained was characterized in terms of water uptake and rheological behavior. In particular, the viscoelastic behavior of the hydrogel was determined in shear stress under dynamic conditions and compared with the behavior of nondegenerated human lumbar NP. We then assessed the effect of the AAA hydrogel on NHC (Normal Human Chondrocyte) cell viability and on the production of important extracellular matrix factors, such as glycosaminoglycans and Type II collagen. In conclusion, the results achieved in this study demonstrated that the amidic alginate-based scaffold is a promising material to be utilized in the replacement of NP.
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