ABSTRACT
BACKGROUND: It is a hotspot that calcium phosphate and calcium sulphate as the main ingredients are combined with one or more other materials to improve or increase the performance of bone tissue engineering scaffolds. OBJECTIVE: To introduce the research advance of these two kinds of scaffolds in bone tissue engineering. METHODS: The articles related to the bone tissue engineering published during January 2000 to June 2015 were retrieved from CNKI and PubMed databases by computer. The key words were “bone tissue engineering, scaffold, calcium phosphate, calcium sulphate, vascularization” in Chinese and English, respectively. ESULTS AND CONCLUSION: Calcium phosphate and calcium sulfate are characterized as having good biocompatibility, biodegradability, osteoconductivity and complete bone substitutability. However, single use of calcium phosphate or calcium sulfate scaffold has certain disadvantages, both of which are difficult to ful y meet the requirements of the bone defect repair. Improvement can be acquired in the mechanical strength, injectability and biodegradability, as wel as drug-loading and pro-angiogenesis of the scaffold in combination with other materials. In the basal and clinical research, we should explore and develop ideal scaffolds in on the basis of therapeutic aim. However, most of the scaffold studies are stil at the extracorporeal and animal experiment stage, and the comparative studies on composite scaffolds and optimal proportion of those composite scaffolds stil need to be further investigated.
ABSTRACT
BACKGROUND:There are so many studies about ovariectomized rats at present, but the research on the change rules of bone mass, bone turnover markers, estrogen levels and their correlation in different periods of ovariectomized rats is rarely reported. OBJECTIVE:To analyze the change rules of bone mass, bone turnover markers, estrogen level and their correlation in different periods of ovariectomized rats. METHODS: Thirty-four 3-month-old female Sprague Dawley rats were randomly divided into three groups: baseline group, ovariectomized group and sham operated group. At the beginning of the experiment, the rats in the baseline group were sacrificed, then rats in the ovariectomized group and sham operated group were executed at 4, 8, 12 weeks postoperative respectively. The bone mineral density, bone mass content, area of different zones of the L1-3 lumbar vertebrae and femurs were detected by dual-energy X-ray absorption method, and meanwhile the serum levels of type I procolagen amino-terminal pro-peptide, I colagen carboxy-terminal peptide and estrogen were determined by ELISA. At last, we analyzed the correlation between body mass, bone mineral densityin vitro, type I procolagen amino-terminal pro-peptide, I colagen carboxy-terminal peptide and estrogen levels and the age of ovariectomized rats. RESULTS AND CONCLUSION: (1) The bone mineral density and bone mass content of the lumbar vertebral and femurs in the ovariectomized group were significantly lower than those in the sham operated group and baseline group at the 4th week after operation (P < 0.05). The bone mineral density and bone mass content in the ovariectomized group were ameliorated obviously at the 8th and 12th weeks compared with those at the 4th week after operation (P < 0.05). The bone mass loss was highest in the L1 and intertrochanteric regions. (2) Serum levels of type I procolagen amino-terminal pro-peptide and I colagen carboxy-terminal peptide in the ovariectomized group were significantly higher than those in the baseline group and sham operated group at the 4th week after operation, but there was no difference at the 8th and 12th weeks. (3) The serum estrogen level in the ovariectomized group was prominently lower than that in the sham operated group and baseline group at the 8th and 12th weeks after operation (P < 0.01 at the 8th week,P < 0.05 at the 12th week). (4) The age was positively correlated with body mass and bone mineral density of the lumbar vertebrae and femursin vitro, while the serum levels of type I procolagen amino-terminal pro-peptide and I colagen carboxy-terminal peptide were negatively correlated with the bone mineral density of the lumbar vertebrae and femurs in vitro (P < 0.01). These results suggested that the bone mass of the lumbar vertebrae and femurs in ovariectomized rats was decreased rapidly firstly, and then rose slowly with time; the bone mass in the L1 and intertrochanteric regions lost seriously; the bone turnover markers showed a significant increase at the beginning of ovariectomy and reduced gradualy to normal condition, while the estrogen level was increased at the first month after ovariectomy and then decreased rapidly. In addition, the body mass, bone turnover markers and estrogen level were associated with the change of bone mass.