Expression of type Ⅰ and type Ⅱ collagen in the healing of denervated tibial fracture in rats :A Western blot analysis / 中国组织工程研究

ABSTRACT

BACKGROUND:It has been recently indicated that nervous factors are able to adjust and dominate bone fracture healing. Type Ⅰ collagen is a major factor to promote the differentiation of osteoblasts and enhance the adhesion of osteoblasts; while, it is also a matrix protein for composing bone framework. Type Ⅱ collagen is derived from chondrocytes. OBJECTIVE: To study changing law of type Ⅰ and Ⅱ collagen expression during denervated bone fracture healing. DESIGN, TIME AND SETTING: Randomized controlled anima study was performed at the Animal Laboratory and Cell Biology Laboratory, the Second Military Medical University of Chinese PLA between May and December 2005. MATERIALS Forty 3-month-year healthy male SD rats were randomly divided into fracture group (tibial fracture alone) and combination group (spinal cord injury combined with tibial fracture), with 20 rats at each group. METHODS: A φ 0.8 mm Kirschner wire was inserted into anterior border of left tibial plateau to establish tibial fracture models in the fracture group. A 0.3-cm spinal cord transection was cut at T10 segment to establish tibial fracture models with entire spinal cord injury. MAIN OUTCOME MEASRUES Type Ⅰ and Ⅱ collagen protein expressions of callus were detected using Western blot technique in week 1, 2, 4, and 5 post-injury. RESULTS: One week after injury, type Ⅰ and Ⅱ collagen was represented in callus in the two groups, while the expressions in the combination group were significantly higher than fracture group (P<0.05); two weeks after injury, type Ⅱ collagen expression reached at the peak in the combination group, and the expression was significantly higher than the fracture group (P<0.05); four weeks after injury, type Ⅰ collagen expression reached at the peak in the fracture group, and the expression was significantly higher than the combination group (P<0.05), while type Ⅱ collagen still highly expressed in the combination group; five weeks after injury, type Ⅰ and Ⅱ collagen expressions were decreased in the two groups. CONCLUSION: Secretory law of type Ⅰ and Ⅱ collagen during denervated bone fracture healing is similar to normal bone fracture healing; however, the differences at time points, in particular expression at peak, are remarkable between them.