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Abstract：
Cystathionine β-synthase (CBS) deficiency is a recessive inborn error of metabolism characterized by extremely elevated total homocysteine (tHcy) in the blood. Patients diagnosed with CBS deficiency have a variety of clinical problems, including dislocated lenses, osteoporosis, cognitive and behavioral issues, and a significantly increased risk of thrombosis. Current treatment strategies involve a combination of vitamin supplementation and restriction of foods containing the homocysteine precursor methionine. Here, a mouse model for CBS deficiency (Tg-I278T Cbs-/-) was used to evaluate the potential of minicircle-based naked DNA gene therapy to treat CBS deficiency. A 2.3 kb DNA-minicircle containing the liver-specific P3 promoter driving the human CBS cDNA (MC.P3-hCBS) was delivered into Tg-I278T Cbs-/- mice via a single hydrodynamic tail vein injection. Mean serum tHcy decreased from 351 μM before injection to 176 μM 7 days after injection (p = 0.0005), and remained decreased for at least 42 days. Western blot analysis reveals significant minicircle-directed CBS expression in the liver tissue. Liver CBS activity increased 34-fold (12.8 vs. 432 units; p = 0.0004) in MC.P3-hCBS-injected animals. Injection of MC.P3-hCBS in young mice, subsequently followed for 202 days, showed that the vector can ameliorate the mouse homocystinuria alopecia phenotype. The present findings show that minicircle-based gene therapy can lower tHcy in a mouse model of CBS deficiency.
摘要：
蛋氨酸β-合酶（CBS）缺乏症是一种隐性的先天性代谢错误，其特征是血液中的总同型半胱氨酸（tHcy）极度升高。被诊断为CBS缺乏症的患者存在各种临床问题，包括脱臼的晶状体,骨质疏松,认知和行为问题，血栓形成的风险显著增加。目前的治疗策略涉及补充维生素和限制含有高半胱氨酸前体甲硫氨酸的食物的组合。这里,CBS缺陷小鼠模型(Tg-I278TCbs-/-)用于评估基于小环的裸DNA基因治疗治疗CBS缺陷的潜力.2.3kb的DNA微环，包含驱动人CBScDNA的肝脏特异性P3启动子（MC。P3-hCBS）通过单次流体动力学尾静脉注射递送到Tg-I278TCbs-/-小鼠中。平均血清tHcy从注射前的351μM下降到注射后7天的176μM（p=0.0005），并保持下降至少42天。Western印迹分析揭示肝组织中显著的微环定向的CBS表达。肝脏CBS活性增加34倍（12.8vs.432个单位；p=0.0004）在MC中。P3-hCBS注射的动物。注射MC。幼鼠的P3-hCBS，随后持续了202天，表明该载体可以改善小鼠高半胱氨酸尿症脱发表型。目前的发现表明，基于微环的基因治疗可以降低CBS缺乏症小鼠模型中的tHcy。
