Herrmann Marietta, Zeiter Stephan, Eberli Ursula, Hildebrand Maria, Camenisch Karin, Menzel Ursula, Alini Mauro, Verrier Sophie, Stadelmann Vincent A
AO Research Institute Davos, Davos, Switzerland.
Front Bioeng Biotechnol. 2018 Feb 12;6:5. doi: 10.3389/fbioe.2018.00005. eCollection 2018.
Bone is an organ with high natural regenerative capacity and most fractures heal spontaneously when appropriate fracture fixation is provided. However, additional treatment is required for patients with large segmental defects exceeding the endogenous healing potential and for patients suffering from fracture non-unions. These cases are often associated with insufficient vascularization. Transplantation of CD34+ endothelial progenitor cells (EPCs) has been successfully applied to promote neovascularization of bone defects, however including extensive manipulation of cells. Here, we hypothesized, that treatment with granulocyte colony-stimulating factor (G-CSF) may improve bone healing by mobilization of CD34+ progenitor cells into the circulation, which in turn may facilitate vascularization at the defect site. In this pilot study, we aimed to characterize the different cell populations mobilized by G-CSF and investigate the influence of cell mobilization on the healing of a critical size femoral defect in rats. Cell mobilization was investigated by flow cytometry at different time points after five consecutive daily G-CSF injections. In a pilot study, bone healing of a 4.5-mm critical femoral defect in F344 rats was compared between a saline-treated control group and a G-CSF treatment group. microcomputed tomography and histology were applied to compare bone formation in both treatment groups. Our data revealed that leukocyte counts show a peak increase at the first day after the last G-CSF injection. In addition, we found that CD34+ progenitor cells, including EPCs, were significantly enriched at day 1, and further increased at day 5 and day 11. Upregulation of monocytes, granulocytes and macrophages peaked at day 1. G-CSF treatment significantly increased bone volume and bone density in the defect, which was confirmed by histology. Our data show that different cell populations are mobilized by G-CSF treatment in cell specific patterns. Although in this pilot study no bridging of the critical defect was observed, significantly improved bone formation by G-CSF treatment was clearly shown.
骨是一种具有高度自然再生能力的器官，在给予适当的骨折固定时，大多数骨折可自发愈合。然而，对于节段性骨缺损超过内源性愈合能力的患者以及骨折不愈合的患者，需要额外的治疗。这些病例通常与血管化不足有关。CD34 + 内皮祖细胞（EPCs）移植已成功应用于促进骨缺损的新血管形成，然而这包括对细胞的广泛操作。在此，我们假设，用粒细胞集落刺激因子（G-CSF）治疗可通过将CD34 + 祖细胞动员到循环中而改善骨愈合，这反过来可能促进缺损部位的血管化。在这项初步研究中，我们旨在表征由G-CSF动员的不同细胞群，并研究细胞动员对大鼠临界尺寸股骨缺损愈合的影响。在连续5天每日注射G-CSF后的不同时间点，通过流式细胞术研究细胞动员情况。在一项初步研究中，比较了生理盐水处理的对照组和G-CSF治疗组的F344大鼠4.5毫米临界股骨缺损的骨愈合情况。应用微型计算机断层扫描和组织学来比较两个治疗组的骨形成情况。我们的数据显示，白细胞计数在最后一次G-CSF注射后的第一天出现峰值增加。此外，我们发现包括EPCs在内的CD34 + 祖细胞在第1天显著富集，并在第5天和第11天进一步增加。单核细胞、粒细胞和巨噬细胞的上调在第1天达到峰值。G-CSF治疗显著增加了缺损部位的骨体积和骨密度，这在组织学上得到了证实。我们的数据表明，G-CSF治疗以细胞特异性模式动员不同的细胞群。虽然在这项初步研究中未观察到临界缺损的桥接，但G-CSF治疗显著改善骨形成的情况已得到明确显示。
