With a homogeneous distribution of hydroxyapatite （HAP） crystals in polymer matrix, composite scaffolds chitosan/HAP and chitosanJcollagen/HAP were fabricated in the study. XRD, SEM and EDX were used to characterize...With a homogeneous distribution of hydroxyapatite （HAP） crystals in polymer matrix, composite scaffolds chitosan/HAP and chitosanJcollagen/HAP were fabricated in the study. XRD, SEM and EDX were used to characterize their components and structure, in vitro cell culture and in vivo animal tests were used to evaluate their biocompatibility. HAP crystals with rod-like shape embeded in chitosan scaffold, while HAP fine-granules bond with collagen/chitosan scaffold compactly. A homogenous distribution of Ca and P elements both in chitosan/HAP scaffold and chitosan/collagen/HAP scaffold was defined by EDX pattern. The presence of collagen brought a more homogenous distribution of HAP due to its higher ability to induce HAP precipitation. The results of in vitro cell culture showed that the composite＇s biocompatibility was enhanced by the homogenous distribution of HAP. In vivo animal studies showed that the in vivo biodegradation was effectively improved by the addition of HAP and collagen, and was less influenced by the homogeneous distribution of HAP when compared with a concentrated distribution one. The composite scaffolds with a homogeneous HAP distribution would be excellent alternative scaffolds for bone tissue engineering.展开更多
Chitooligosaccharide (COS) is derived from the chemical and enzymatic hydrolysis of chitosan and has been reported to have potent antitumor activity.Our study investigated the effects of five chitooligomers ranging fr...Chitooligosaccharide (COS) is derived from the chemical and enzymatic hydrolysis of chitosan and has been reported to have potent antitumor activity.Our study investigated the effects of five chitooligomers ranging from the dimer form to the hexamer form (chitobiose,chitotriose,chitotetraose,chitopentaose,chitohexaose) on the expression of cyclin D1,bcl-2 and bcl-xl mRNA in A549 cells using reverse transcription quantitative real-time PCR.We demonstrated that,of the five chitooligomers used,chitohexaose (COS6) had the most potent inhibitory effect on A549 cell proliferation.COS6 also significantly down regulated cyclin D1 and bcl-xl mRNA expression levels.Our data suggested that COS6 exerts its antitumor activity by two different mechanisms:(1) COS6-mediated inhibition of Cyclin D1 levels leads to suppression of tumor cell proliferation;and (2) COS6-mediated down-regulation of the pro-survival protein,Bcl-xl,promotes the apoptosis of tumor cells.展开更多
基金the National High Technology Development Program (No. 2007AA091603)the National Natural Science Foundation of China (Nos. 30870612 and 20604010)
文摘With a homogeneous distribution of hydroxyapatite （HAP） crystals in polymer matrix, composite scaffolds chitosan/HAP and chitosanJcollagen/HAP were fabricated in the study. XRD, SEM and EDX were used to characterize their components and structure, in vitro cell culture and in vivo animal tests were used to evaluate their biocompatibility. HAP crystals with rod-like shape embeded in chitosan scaffold, while HAP fine-granules bond with collagen/chitosan scaffold compactly. A homogenous distribution of Ca and P elements both in chitosan/HAP scaffold and chitosan/collagen/HAP scaffold was defined by EDX pattern. The presence of collagen brought a more homogenous distribution of HAP due to its higher ability to induce HAP precipitation. The results of in vitro cell culture showed that the composite＇s biocompatibility was enhanced by the homogenous distribution of HAP. In vivo animal studies showed that the in vivo biodegradation was effectively improved by the addition of HAP and collagen, and was less influenced by the homogeneous distribution of HAP when compared with a concentrated distribution one. The composite scaffolds with a homogeneous HAP distribution would be excellent alternative scaffolds for bone tissue engineering.
基金supported by the National High Technology Research and Development Program of China (2007AA091603)
文摘Chitooligosaccharide (COS) is derived from the chemical and enzymatic hydrolysis of chitosan and has been reported to have potent antitumor activity.Our study investigated the effects of five chitooligomers ranging from the dimer form to the hexamer form (chitobiose,chitotriose,chitotetraose,chitopentaose,chitohexaose) on the expression of cyclin D1,bcl-2 and bcl-xl mRNA in A549 cells using reverse transcription quantitative real-time PCR.We demonstrated that,of the five chitooligomers used,chitohexaose (COS6) had the most potent inhibitory effect on A549 cell proliferation.COS6 also significantly down regulated cyclin D1 and bcl-xl mRNA expression levels.Our data suggested that COS6 exerts its antitumor activity by two different mechanisms:(1) COS6-mediated inhibition of Cyclin D1 levels leads to suppression of tumor cell proliferation;and (2) COS6-mediated down-regulation of the pro-survival protein,Bcl-xl,promotes the apoptosis of tumor cells.
