Trauma Department, Hannover Medical School, 30625 Hannover, Germany.
Injury. 2013 Oct;44(10):1279-84. doi: 10.1016/j.injury.2013.05.011. Epub 2013 Jun 15.
In multiple trauma patients an increased incidence of delayed healing and non-union has been observed. The exact mechanisms underlying this delayed fracture healing are still not fully understood.
40 male C57BL/6N-mice underwent standardized midline laparotomy and pressure-controlled haemorrhage (TH) or implantation of catheters without blood loss (sham procedure). Animals were sacrificed 24h or 72 h later. Osteoprogenitor cells derived from bone marrow were isolated and differentiated into osteoblasts for 20 days and osteoclasts for 7 days. Osteoblast mineralization and osteoclast numbers were determined, and gene expression of Alpl, Bglap, Opg, Rankl was measured in osteoblast cell culture, as well as gene expression of Rank, Ctsk and Nfatc1 was determined in osteoclast cell culture. Furthermore, plasma Opg, Rankl and TRAP were measured.
Mineralization capacity of osteoblasts was unchanged after TH, but Alpl gene expression after 23 days was significantly decreased compared to sham. Osteoclast number of group TH 8 days was significantly decreased compared to sham. Furthermore, gene expression of Ctsk and Nfatc1 were increased in group TH 10 days compared to group TH 8 days. Plasma Opg concentration was significantly elevated and Rankl concentrations were significantly declined in TH groups compared to sham groups after 24h and 72 h.
TH results in a diminished osteoclast number after 8 days, whereas differentiation of osteoblasts seems to be unaffected. The reduction of osteoclast number seems to be mediated through the Rankl-Opg-signalling pathway. However, further studies in models including a fractured extremity with a longer observation period are needed to identify the relevance of the Rankl-Opg- pathway in delayed fracture healing after TH and to focus on possible therapeutic interventions.
在多发伤患者中，观察到愈合延迟和不愈合的发生率增加。导致这种骨折愈合延迟的确切机制尚不完全清楚。
40 只雄性 C57BL/6N 小鼠接受了标准的中线剖腹术和压力控制出血（TH）或无失血（假手术）导管植入。动物在 24 小时或 72 小时后被处死。从骨髓中分离出成骨细胞前体细胞并分化为成骨细胞 20 天和破骨细胞 7 天。在成骨细胞培养中测定成骨细胞的矿化能力和破骨细胞数量，并测定 Alpl、Bglap、Opg、Rankl 的基因表达，在破骨细胞培养中测定 Rank、Ctsk 和 Nfatc1 的基因表达。此外，还测量了血浆 Opg、Rankl 和 TRAP。
TH 后成骨细胞的矿化能力没有改变，但与假手术组相比，第 23 天的 Alpl 基因表达显著降低。TH 组第 8 天的破骨细胞数量明显低于假手术组。此外，与 TH 组第 8 天相比，TH 组第 10 天的 Ctsk 和 Nfatc1 基因表达增加。与假手术组相比，TH 组在 24 小时和 72 小时后血浆 Opg 浓度显著升高，Rankl 浓度显著降低。
TH 导致第 8 天破骨细胞数量减少，而成骨细胞分化似乎不受影响。破骨细胞数量的减少似乎是通过 Rankl-Opg 信号通路介导的。然而，需要在包括骨折肢体在内的模型中进行进一步的研究，以确定 TH 后骨折愈合延迟中 Rankl-Opg 通路的相关性，并关注可能的治疗干预措施。
