RESUMO
The development of blended biomacromolecule and polyester scaffolds can potentially be used in many tissue engineering applications. This study was to develop a poly(gamma-glutamic acid)-graft-chondroitin sulfate-blend-poly(epsilon-caprolactone) (gamma-PGA-g-CS/PCL) composite biomaterial as a scaffold for cartilage tissue engineering. Chondroitin sulfate (CS) was grafted to gamma-PGA, forming a gamma-PGA-g-CS copolymer with 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide (EDC) system. The gamma-PGA-g-CS copolymers were then blended with PCL to yield a porous gamma-PGA-g-CS/PCL scaffold by salt leaching. These blended scaffolds were characterized by (1)H NMR, ESCA, water-binding capacity, mechanical test, degradation rate and CS assay. The results showed that with gamma-PGA-g-CS as a component, the water-binding capacity and the degradation rate of the scaffolds would substantially increase. During a 4 week period of culture, the mechanical stability of gamma-PGA-g-CS/PCL scaffolds was raised gradually and chondrocytes were induced to function normally in vitro. Furthermore, a larger amount of secreted GAGs was present in the gamma-PGA-g-CS/PCL matrices than in the control (PCL), as revealed by Alcian blue staining of the histochemical sections. Thus, gamma-PGA-g-CS/PCL matrices exhibit excellent biodegradation and biocompatibility for chondrocytes and have potential in tissue engineering as temporary substitutes for articular cartilage regeneration.
Assuntos
Cartilagem Articular/crescimento & desenvolvimento , Condrócitos/fisiologia , Condrogênese/fisiologia , Sulfatos de Condroitina/química , Poliésteres/química , Ácido Poliglutâmico/análogos & derivados , Engenharia Tecidual/métodos , Animais , Materiais Biocompatíveis/química , Técnicas de Cultura de Células/métodos , Células Cultivadas , Condrócitos/citologia , Matriz Extracelular/química , Feminino , Teste de Materiais , Ácido Poliglutâmico/química , Porosidade , Ratos , Ratos WistarRESUMO
The effects of poly-gamma-glutamic acid (gamma-PGA) on calcium (Ca) bioavailability and Ca content in bone were examined in female rats. Increases in in vitro Ca solubility was observed with increases in the amount of gamma-PGA. Acute studies showed that gamma-PGA increased the amount of soluble Ca in the small intestine. In a plasma-Ca kinetic experiment, gamma-PGA stimulated Ca absorption 20 min after administration, and the duration of absorption was approximately 2 h. In an acute intestinal transit experiment, gamma-PGA markedly increased intestinal transit in mice. In a chronic Ca-balance experiment, the results showed that gamma-PGA significantly increased the apparent Ca absorption, apparent Ca balance, bone density, and bone Ca content in rats. In the same experiment, gamma-PGA was also found to decrease the amount of soluble Ca in the small intestine, especially in the proximal small intestine, and to increase calbindin-D9k mRNA expression in the proximal small intestine in rats. In a chronic intestinal transit experiment, gamma-PGA decreased intestinal transit in mice. These results suggest that gamma-PGA increased Ca solubility, thereby enhancing Ca absorption in rats in the acute phase. In addition, chronic administration of gamma-PGA to rats increased the apparent Ca balance and bone Ca content. The active transcellular pathway in the proximal small intestine was the major mechanism by which these effects were exerted.
