ABSTRACT
BACKGROUND:Increasing attention has been paid on the role of advanced glycation end products in bone tissue. Glucose metabolic disorder is one of the main reasons for the increase of advanced glycation end products. OBJECTIVE:To observe the change of advanced glycation end products expressed in type 2 diabetes rats, and to investigate the relationship between impaired fracture healing and change of advanced glycation end products expression in vivo. METHODS:Thirty Sprague-Dawley rats were randomly and equal y divided into two groups:control group (normal feeding) and experimental group (high fat and sucrosum diet feeding to establish type 2 diabetes model). After diabetes models were established, the model of distraction osteogenesis in the left tibiae of al the rats was produced. Distraction was given 0.3 mm per day and continued for 14 days. RESULTS AND CONCLUSION:After the traction was complete, cal us formation in distraction gap was obviously reduced in experimental group compared with control group by X-ray examination. The array of microcolumn formation was disordered and the area of primary matrix front was catachromasis by histology examination. The enzyme-linked immunosorbent assay results showed that, the level of advanced glycation end products was obviously elevated (P<0.01) while osteocalcin was obviously reduced (P<0.01) in experimental group in comparison with control group. The formation of distraction cal us was impaired in the process of fracture healing and blood of type 2 diabetes rats. The increase of advanced glycation end products may be one of the reasons that cause impaired fracture healing in diabetic rats.
ABSTRACT
BACKGROUND: It was reported that the reason why the fracture healing become more and more difficult with the increasing age may be associated with the varied gene regulation of bone marrow mesenchymal stem cells differentiation into osteoblast and lipoblast. However, the exact mechanism under it remains poorly understood.OBJECTIVE: To explore the association of the age-related changes on expression of peroxisome proliferator-activated receptor γ (PPARγ) and core binding α1 (Cbfα1) with the age-relatad fracture healing impairment, we studied the expression changes of PPARγ and Cbfα1 during aging fracture healing.DESIGN, TIME AND SETTING: A randomized control animal trial was performed in the Third Xiangya Hospital of Central South University between October 2007 and Febuary 2008. MATERIALS: Six male SD rats of 3 months and the other six of 23 months, randomly-selected, were divided into two groups: the old experiment group (23 months) and the young control group (3 months). METHODS: Transverse osteotomies on the middle-upper parts of left tibiae were performed to the rats, with the self-made extemal mini-fixator implanted there simultaneously. Tractions were taken twice a day (0.2 mm/d) for 14 days from day 2 till day 15 post operation. On day 15 post operation, rats were sacrificed to harvest left tibea samples. MAIN OUTCOME MEASURES: Both imaging examination and histological observation were performed to the fractures of rats. The PPARγ and Cbfα1 expression were detected with reverse transcription-polymerase chain reaction (RT-PCR) technique. RESULTS: All samples were involved in the results analyses. The imaging examination showed that many osteotylus generated between the broken ends of fractures in the young control group; that the bone formation of the young control group was much better than that of the old experiment group. The histological observation showed that large amounts of osteotylus growth occurred to every animal in the young control group and their membrane bone formation was remarkable; comparatively, the osteotylus growth in the old group was weakened dramatically, and only fibrous joints were seen. The RT-PCR detection showed that differences of significance existed in both PPARγ and Cbfα1 mRNA expressions between the two groups, with the much higher Cbfol mRNA expression in the bone marrow of rats in the young group and the much higher PPARy mRNA expression in the bone marrow of rats in the old group.CONCLUSION: Rats of different ages show different fracture healing abilities, i.e. the higher ages, the lower fracture healing abilities. In addition, expressions of PPARγ and Cbfα1 in the bone marrow of rats alter with the increasing age, which indicates that there are certain associations between the changed expression level of the two factors and the fracture healing impartment.