title: Recombinant proteins secreted from tissue-engineered bioartificial muscle improve cardiac dysfunction and suppress cardiomyocyte apoptosis in rats with heart failure.
abstract: BACKGROUND
  Tissue-engineered bioartificial muscle-based gene therapy represents a promising approach for the treatment of heart diseases. Experimental and clinical studies suggest that systemic administration of insulin-like growth factor-1 (IGF-1) protein or overexpression of IGF-1 in the heart exerts a favorable effect on cardiovascular function. This study aimed to investigate a chronic stage after myocardial infarction (MI) and the potential therapeutic effects of delivering a human IGF-1 gene by tissue-engineered bioartificial muscles (BAMs) following coronary artery ligation in Sprague-Dawley rats.
  
  
  METHODS
  Ligation of the left coronary artery or sham operation was performed. Primary skeletal myoblasts were retrovirally transduced to synthesize and secrete recombinant human insulin-like growth factor-1 (rhIGF-1), and green fluorescent protein (GFP), and tissue-engineered into implantable BAMs. The rats that underwent ligation were randomly assigned to 2 groups: MI-IGF group (n = 6) and MI-GFP group (n = 6). The MI-IGF group received rhIGF-secreting BAM (IGF-BAMs) transplantation, and the MI-GFP group received GFP-secreting BAM (GFP-BAMs) transplantation. Another group of rats served as the sham operation group, which was also randomly assigned to 2 subgroups: S-IGF group (n = 6) and S-GFP group (n = 6). The S-IGF group underwent IGF-1-BAM transplantation, and S-GFP group underwent GFP-BAM transplantation. IGF-1-BAMs and GFP-BAMs were implanted subcutaneously into syngeneic rats after two weeks of operation was performed. Four weeks after the treatment, hemodynamics was performed. IGF-1 was measured by radioimmunoassay, and then the rats were sacrificed and ventricular samples were subjected to immunohistochemistry. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine the mRNA expression of bax and Bcl-2. TNF-α and caspase 3 expression in myocardium was examined by Western blotting.
  
  
  RESULTS
  Primary rat myoblasts were retrovirally transduced to secrete rhIGF-1 and tissue-engineered into implantable BAMs containing parallel arrays of postmitotic myofibers. In vitro, they secreted consistent levels of hIGF (0.4 - 1.2 µg×BAM(-1)×d(-1)). When implanted into syngeneic rat, IGF-BAMs secreted and delivered rhIGF. Four weeks after therapy, the hemodynamics was improved significantly in MI rats treated with IGF-BAMs compared with those treated with GFP-BAMs. The levels of serum IGF-1 were increased significantly in both MI and sham rats treated with IGF-BAM. The mRNA expression of bax was lower and Bcl-2 expression was higher in MI-IGF group than MI-GFP group (P < 0.05). Western blotting assay showed TNF-α and caspase 3 expression was lower in MI-IGF group than MI-GFP group after therapy.
  
  
  CONCLUSIONS
  rhIGF-1 significantly improves left ventricular function and suppresses cardiomyocyte apoptosis in rats with chronic heart failure. Genetically modified tissue-engineered BAMs provide a method delivering recombinant protein for the treatment of heart failure.
authors.affiliation: Department of Cardiology, Heping Hospital, Changzhi Medical College, Changzhi, Shanxi 046000, China.
authors.forename: Shu-Ling
authors.initials: SL
authors.lastname: Rong
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Wang
authors.forename: Xiao-Lin
authors.initials: XL
authors.lastname: Wang
authors.forename: Yong-Xin
authors.initials: YX
authors.lastname: Lu
authors.forename: Yin
authors.initials: Y
authors.lastname: Wu
authors.forename: Qi-Yun
authors.initials: QY
authors.lastname: Liu
authors.forename: Shao-Hua
authors.initials: SH
authors.lastname: Mi
authors.forename: Yu-Lan
authors.initials: YL
authors.lastname: Xu
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000032:analysis; D003893:Desmin / Q000032:analysis; D015316:Genetic Therapy; D006333:Heart Failure / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D032448:Myoblasts, Skeletal / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D023822:Tissue Engineering; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D016277:Ventricular Function, Left
chemical_list: D003893:Desmin; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I; D053148:Caspase 3