The Function And Mechanism Of Cranial Bone Fracture In Accelerated New Bone Forming In Fracture Associated With Traumatic Brain Injury

There is a common clinical phenomenon: if a fractured patient has traumatic brain injury (TBI) at the same time, his fracture healing process will be accelerated and heterotopic ossification can be found near some joint. There were some clinical reports and experimental studies about this phenomenon. Lots of hypotheses were made but the mechanism of this phenomenon isn' t clear so far. Most of hypotheses aimed at whether brain components be released after traumatic brain injury and some factors that can accelerate the fracture healing were in it. But no hypotheses and study aimed at whether cranial bone components be released after traumatic brain injury and some factors that can accelerate the fracture healing.Purpose:To explore the function and mechanism of cranial bone fracture in accelerated new bone forming combined with traumatic brain injury. To study the effect of blood plasma derived from rats with traumatic brain injury and femur fracture on the BMSCs. To explore the effect of cranial bone transplantation on fracture healing. To study the expression of IGFBP-5 in cranial bones and the effect of it on BMSCs proliferation, differentiation and mineralization.Methods:The research can be divided into 4 parts below:1. To compare the effect of cranial bone fracture, traumatic brain injury on fracture healing after constructing animal model.2. Explore the methods of isolation, purification, culture and identification of BMSCs.3. Compare the effect of blood plasma extracted from the rats of CBF+F group, TBI+F group and F group on BMSCs proliferation, differentiation, and mineralization. Compare the effect of soaked liquid of cranial bone and iliac bone on BMSCs proliferation, differentiation, and mineralization.4. Explore the expression of IGFBP-5 in cranial bone, iliac bone and femur. Compare the effect of different IGFBP-5 content on BMSCs proliferation, differentiation and mineralization. Remove IGFBP-5 of TBI+F blood plasma and compare the effect of this blood plasma with common TBI+F blood plasma on BMSCs proliferation, differentiation and mineralization.Result:After constructing animal model, the 4-week callus volume of CBF+F group is larger than simple fracture group(P<0.05),but minor than TBI+F group(P<0.05). The bone density and the biomechanics results of callus demonstrate that there was no statistics difference between the CBF+F group and TBI+F group(P>0.05). But the results of these two group were minor than simple fracture group (P<0.05). The HE stain results of callus showed that CBF+F group were similar to TBI+F group in histomorphology and they had more difference comparing with the simple fracture group. The blood plasma derived from the rats of CBF+F group had more powerful stimulating ability in BMSCs proliferation, differentiation, and mineralization than F group(P<0.05), but had less stimulating ability than TBI+F group(P<0.05). The soaked liquid of cranial bones had had more powerful stimulating ability in BMSCs proliferation, differentiation, and mineralization than soakedliquid of iliac bone group(P<0.05). The IGFBP-5 contents of the animal models were peaked at 8 hours after surgery and decreased stepwise. There were no significant difference between surgery groups and normal rats at 5 days after surgery. The IGFBP-5 content of CBF+F group was 2.83 times as simple fracture group and 3.12 times as normal group.Conclusion:1. Cranial bones fracture can stimulate new bone forming and it was important factor in TBI accelerating new bone forming.2. The cranial bones transplantation have more powerful ability in accelerating new bone forming than iliac bone transplantation.3. IGFBP-5 were mostly exist in cranial bones and it has powerful stimulating ability in BMSCs proliferation, differentiation, and mineralization. IGFBP-5 is one important factor in TBI accelerating new bone forming.