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颅骨骨折在脑外伤促新骨形成过程中的作用及机制研究
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摘要
临床工作中发现伴有脑外伤的骨折病人,其骨痂生长明显增多加快,甚至在某些关节周围出现异位骨化。关于此现象国内外均有临床报道和基础研究,提出了很多假说,但其中机制迄今仍不明朗。目前提出的机制多数是针对脑外伤后是否会导致脑组织内某些成份释放入血液系统促进新骨形成,但没有关于颅骨骨折是否会引起颅骨中的某些成分进入血液系统促进新骨形成的研究和报道。
     目的:
     探讨颅骨骨折在脑外伤促新骨形成过程中的作用;研究颅骨骨折伴股骨骨折组大鼠血浆对骨髓间质细胞的作用;研究颅骨移植对骨折愈合的影响作用;研究IGFBP-5在颅骨组织中的表达情况,及其对骨髓间质细胞的作用。
     方法:
     研究分以下几个部分进行:
     1.建立实验动物模型,比较颅骨骨折伴股骨骨折、脑外伤伴股骨骨折及单纯股骨骨折后骨折愈合的情况。
     2.进行大鼠骨髓间充质干细胞的分离、培养、纯化及鉴定。
     3.比较颅骨骨折组血浆、脑外伤组血浆及单纯骨折组血浆对大鼠骨髓间充质细胞增殖、分化及矿化功能的影响;比较颅骨浸泡液、髂骨浸泡液对大鼠骨髓间充质细胞增殖、分化及矿化功能的影响。
     4.研究IGFBP-5在颅骨、髂骨及股骨中的表达,比较不同浓度IGFBP-5对大鼠骨髓间充质细胞增殖、分化及矿化功能的影响;去除脑外伤组血浆中的IGFBP-5,比较其与未处理脑外伤组血浆对大鼠骨髓间充质细胞增殖、分化及矿化功能的影响。
     结果:
     1.通过建立脑外伤、颅骨骨折及股骨骨折动物模型,实验结果显示术后4周颅骨骨折组生成骨痂体积比单纯骨折组骨痂大(P<0.05),但小于脑外伤组(P<0.05);骨折断端骨密度检测结果显示颅骨骨折组与颅脑损伤组无明显差异(P>0.05),但两组都低于单纯骨折组(P<0.05);组织形态学HE染色显示颅骨骨折组与脑外伤组类似,但不同与单纯骨折组。
     2.采用密度梯度离心法和贴壁筛选法相结合,利用Ficoll分离液能有效地将大部分造血细胞和单个核细胞分离开来,再经过体外贴壁培养,去除悬浮生长的造血系细胞,所获得的BMSCs纯度高且活性强。
     3.颅骨移植组骨痂体积明显大于髂骨移植(P<0.05)和单纯骨折组(P<0.05)。骨折断端骨密度检测结果显示颅骨移植组低于单纯骨折组及髂骨移植组(P<0.05);组织形态学HE染色显示颅骨移植组不同于髂骨移植组和单纯骨折组; CBF+F血浆组细胞在增殖、向成骨细胞分化及促进钙结节生成能力均较F组血浆培养组强,二者比较有统计学差异(P<0.05),但较TBI+F动物血浆培养组数量差,二者比较有统计学差异(P<0.05);颅骨浸泡液在增殖、向成骨细胞分化及促进钙结节生成能力三方面均较髂骨浸泡液强(P<0.05)。
     4.各骨折组动物模型血浆中IGFBP-5浓度于骨折后第8小时达到高峰,此后逐渐减低,至术后第5天时,各组血浆IGFBP-5浓度与正常组血浆无差别。骨折后8小时CBF+F组血浆IGFBP-5浓度是单纯骨折组血浆IGFBP-5浓度的2.83倍,是正常大鼠血浆IGFBP-5浓度的3.12倍。
     结论:
     1.颅骨骨折可促进新骨形成,颅骨骨折在脑外伤促新骨形成过程中起着重要作用。
     2.颅骨移植促进新骨形成作用强于髂骨移植。
     3. IGFBP-5在颅骨中高表达,且具有促BMSCs增殖、向成骨细胞分化及钙化的作用,在颅骨骨折促新骨形成过程中起着重要作用。
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.
引文
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