Segmental bone defects are often performed with cryopreserved allografts. They provide immediate stability, but risk nonunion, infection and late stress fracture. Improving the rate and extent of bone revitalization may improve results. Angiogenesis from surgically placed arteriovenous (AV) bundles improves bone blood flow and vitality in cryopreserved rat femora, augmented by vasculogenic growth factors. This study tests the same principal in Yucatan mini-pigs with a tibial diaphyseal defect, combining surgical angiogenesis with angiogenic gene therapy within cryopreserved orthotopically-placed allografts. Tibial diaphyseal defects were reconstructed with cryopreserved allografts and rigid internal fixation in 16 mini pigs. Half of the cranial tibial AV bundles placed within the allograft medullary canal were transfected with an adeno-associated virus containing vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) genes (AAV9.VEGF.PDGF). Bone remodeling, angiogenesis, and allograft healing were assessed. During the postoperative survival period 5 of 8 transfected animals developed cutaneous benign vascular lesions at sites remote from the operated hindlimb, causing excessive bleeding. Within the allograft, both medullary (p = 0.013) and cortical (p = 0.009) vascular volumes were higher and vessels more mature than nontransfected allografts. Bone turnover (p = 0.013), bone mineralization (p = 0.018), bone healing (p = 0.008) and graft incorporation (p = 0.006) were all significantly higher in the gene therapy group. In a large animal tibial defect model, gene therapy of implanted AV bundles improved revascularization, remodeling and healing of cryopreserved allografts used for limb reconstruction. However, benign vascular lesions causing excessive bleeding developed in 5 out of 8 pigs transfected with AAV containing genes for VEGF and PDGF. This unforeseen complication makes vasculogenic gene therapy unacceptable for clinical use.

中文翻译：

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血管生成基因治疗：对同种异体结构骨的再生没有作用


节段性骨缺损通常采用冷冻保存的同种异体移植物进行。它们可以提供即时的稳定性，但存在骨不连、感染和晚期应力性骨折的风险。提高骨再生的速度和程度可能会改善结果。手术放置的动静脉 (AV) 束的血管生成改善了冷冻保存的大鼠股骨的骨血流量和活力，并通过血管生成因子增强。这项研究在具有胫骨骨干缺陷的尤卡坦小型猪中测试了相同的原理，将手术血管生成与冷冻保存的原位放置的同种异体移植物中的血管生成基因疗法相结合。采用低温保存的同种异体移植物和刚性内固定技术对16头小型猪进行胫骨骨干缺损重建。放置在同种异体移植髓管内的一半颅骨胫骨 AV 束用含有血管内皮生长因子 (VEGF) 和血小板衍生生长因子 (PDGF) 基因 (AAV9.VEGF.PDGF) 的腺相关病毒转染。评估骨重塑、血管生成和同种异体移植愈合。在术后存活期间，8只转染动物中有5只在远离手术后肢的部位出现皮肤良性血管病变，导致出血过多。在同种异体移植物中，与未转染的同种异体移植物相比，髓质（ p = 0.013）和皮质（ p = 0.009）血管体积更大，血管更成熟。基因治疗组的骨转换（ p = 0.013）、骨矿化（ p = 0.018）、骨愈合（ p = 0.008）和移植物掺入（ p = 0.006）均显着较高。 在大型动物胫骨缺损模型中，植入 AV 束的基因治疗改善了用于肢体重建的冷冻同种异体移植物的血运重建、重塑和愈合。然而，在转染含有 VEGF 和 PDGF 基因的 AAV 的 8 头猪中，有 5 头出现良性血管病变，导致过度出血。这种不可预见的并发症使得血管生成基因治疗在临床上无法接受。