Biomedical Engineering, University of Virginia Health System, Charlottesville, VA 22908, USA.
Cell Tissue Res. 2012 Mar;347(3):553-66. doi: 10.1007/s00441-011-1217-3. Epub 2011 Aug 24.
Endogenous stem cell recruitment to the site of skeletal injury is key to enhanced osseous remodeling and neovascularization. To this end, this study utilized a novel bone allograft coating of poly(lactic-co-glycolic acid) (PLAGA) to sustain the release of FTY720, a selective agonist for sphingosine 1-phosphate (S1P) receptors, from calvarial allografts. Uncoated allografts, vehicle-coated, low dose FTY720 in PLAGA (1:200 w:w) and high dose FTY720 in PLAGA (1:40) were implanted into critical size calvarial bone defects. The ability of local FTY720 delivery to promote angiogenesis, maximize osteoinductivity and improve allograft incorporation by recruitment of bone progenitor cells from surrounding soft tissues and microcirculation was evaluated. FTY720 bioactivity after encapsulation and release was confirmed with sphingosine kinase 2 assays. HPLC-MS quantified about 50% loaded FTY720 release of the total encapsulated drug (4.5 μg) after 5 days. Following 2 weeks of defect healing, FTY720 delivery led to statistically significant increases in bone volumes compared to controls, with total bone volume increases for uncoated, coated, low FTY720 and high FTY720 of 5.98, 3.38, 7.2 and 8.9 mm(3), respectively. The rate and extent of enhanced bone growth persisted through week 4 but, by week 8, increases in bone formation in FTY720 groups were no longer statistically significant. However, micro-computed tomography (microCT) of contrast enhanced vascular ingrowth (MICROFIL®) and histological analysis showed enhanced integration as well as directed bone growth in both high and low dose FTY720 groups compared to controls.
内源性干细胞招募到骨骼损伤部位对于增强骨重塑和新生血管形成至关重要。为此,本研究利用一种新型骨同种异体涂层聚(乳酸-共-乙醇酸)(PLAGA)来持续释放 FTY720,FTY720 是一种鞘氨醇 1-磷酸(S1P)受体的选择性激动剂,从颅骨同种异体移植物中释放。未涂层同种异体移植物、载体涂层、PLAGA 中的低剂量 FTY720(1:200w:w)和 PLAGA 中的高剂量 FTY720(1:40)被植入临界尺寸颅骨骨缺损中。通过从周围软组织和微循环招募骨祖细胞来促进血管生成、最大限度地发挥成骨诱导作用并改善同种异体移植物整合的局部 FTY720 传递能力进行了评估。用鞘氨醇激酶 2 测定法证实了包封和释放后的 FTY720 生物活性。HPLC-MS 定量分析了 5 天后约 50%负载的 FTY720 释放量(4.5μg)占总包裹药物的 4.5μg。在缺陷愈合 2 周后,与对照组相比,FTY720 给药导致骨体积显着增加,未涂层、涂层、低 FTY720 和高 FTY720 的总骨体积增加分别为 5.98、3.38、7.2 和 8.9mm3。增强骨生长的速度和程度一直持续到第 4 周,但到第 8 周,FTY720 组的骨形成增加不再具有统计学意义。然而,对比增强血管内生长(MICROFIL®)的微计算机断层扫描(microCT)和组织学分析表明,与对照组相比,高剂量和低剂量 FTY720 组的整合和定向骨生长都得到了增强。