Murry C E, Kay M A, Bartosek T, Hauschka S D, Schwartz S M
Department of Pathology, University of Washington, Seattle 98195, USA.
J Clin Invest. 1996 Nov 15;98(10):2209-17. doi: 10.1172/JCI119030.
Myocardial infarcts heal by scar formation because there are no stem cells in myocardium, and because adult myocytes cannot divide and repopulate the wound. We sought to redirect the heart to form skeletal muscle instead of scar by transferring the myogenic determination gene, MyoD, into cardiac granulation (wound repair) tissue. A replication-defective adenovirus was constructed containing MyoD under transcriptional control of the Rous sarcoma virus long terminal repeat. The virus converted cultured cardiac fibroblasts to skeletal muscle, indicated by expression of myogenin and skeletal myosin heavy chains (MHCs). To determine if MyoD could induce muscle differentiation in vivo, we injected 2 x 10(9) or 10(10) pfu of either the MyoD or a control beta-galactosidase adenovirus into healing rat hearts, injured 1 wk previously by freeze-thaw. After receiving the lower viral dose, cardiac granulation tissue expressed MyoD mRNA and protein, but did not express myogenin or skeletal MHC. When the higher dose of virus was administered, double immunostaining showed that cells in reparative tissue expressed both myogenin and embryonic skeletal MHC. No muscle differentiation occurred after beta-galactosidase transfection. Thus, MyoD gene transfer can induce skeletal muscle differentiation in healing heart lesions. Modifications of this strategy might eventually provide new contractile tissue to repair myocardial infarcts.
心肌梗死通过瘢痕形成来愈合，这是因为心肌中不存在干细胞，而且成年心肌细胞无法分裂并重新填充伤口。我们试图通过将生肌决定基因MyoD导入心脏肉芽组织（伤口修复组织），使心脏转而形成骨骼肌而非瘢痕。构建了一种复制缺陷型腺病毒，其在劳氏肉瘤病毒长末端重复序列的转录控制下包含MyoD。该病毒将培养的心脏成纤维细胞转化为骨骼肌，这可通过肌细胞生成素和骨骼肌肌球蛋白重链（MHCs）的表达来表明。为了确定MyoD在体内是否能诱导肌肉分化，我们将2×10⁹或10¹⁰个噬斑形成单位（pfu）的MyoD腺病毒或对照β-半乳糖苷酶腺病毒注射到1周前经冻融损伤的正在愈合的大鼠心脏中。接受较低病毒剂量后，心脏肉芽组织表达MyoD mRNA和蛋白，但不表达肌细胞生成素或骨骼肌MHC。当给予较高剂量的病毒时，双重免疫染色显示修复组织中的细胞同时表达肌细胞生成素和胚胎骨骼肌MHC。β-半乳糖苷酶转染后未发生肌肉分化。因此，MyoD基因转移可诱导正在愈合的心脏损伤部位发生骨骼肌分化。对该策略的改进最终可能会提供新的收缩组织来修复心肌梗死。
