Recombinant human growth hormone secreted from tissue-engineered bioartificial muscle improves left ventricular function in rat with acute myocardial infarction.
BACKGROUND
Experimental studies and preliminary clinical studies have suggested that growth hormone (GH) treatment may improve cardiovascular parameters in chronic heart failure (CHF). Recombinant human GH (rhGH) has been delivered by a recombinant protein, by plasmid DNA, and by genetically engineered cells with different pharmacokinetic and physiological properties. The present study aimed to examine a new method for delivery of rhGH using genetically modified bioartificial muscles (BAMs), and investigate whether the rhGH delivered by this technique improves left ventricular (LV) function in rats with CHF.


METHODS
Primary skeletal myoblasts were isolated from several Sprague-Dawley (SD) rats, cultured, purified, and retrovirally transduced to synthesize and secrete human rhGH, and tissue-engineered into implantable BAMs. Ligation of the left coronary artery or sham operation was performed. The rats that underwent ligation were randomly assigned to 2 groups: CHF control group (n = 6) and CHF treatment group (n = 6). The CHF control group received non-rhGH-secreting BAM (GFP-BAMs) transplantation, and the CHF treatment group received rhGH-secreting BAM (GH-BAMs) transplantation. Another group of rats served as the sham operation group, which was also randomly assigned to 2 subgroups: sham control group (n = 6) and sham treatment group (n = 6). The sham control group underwent GFP-BAM transplantation, and the sham treatment group underwent GH-BAM transplantation. GH-BAMs and GFP-BAMs were implanted subcutaneously into syngeneic rats with ligation of the left coronary artery or sham operation was performed. Eight weeks after the treatment, echocardiography was performed. hGH, insulin-like growth factor-1 (IGF-1) and TNF-alpha levels in rat serum were measured by radioimmunoassay and ELISA, and then the rats were killed and ventricular samples were subjected to immunohistochemistry.


RESULTS
Primary rat myoblasts were retrovirally transduced to secrete rhGH and tissue-engineered into implantable BAMs containing parallel arrays of postmitotic myofibers. In vitro, they secreted 1 to 2 microg of bioactive rhGH per day. When implanted into syngeneic rat, GH-BAMs secreted and delivered rhGH. Eight weeks after therapy, LV ejection fraction (EF) and fractional shortening (FS) were significantly higher in CHF rats treated with GH-BAMs than in those treated with GFP-BAMs ((65.0 +/- 6.5)% vs (48.1 +/- 6.8)%, P < 0.05), ((41.3 +/- 7.4)% vs (26.5 +/- 7.1)%, P < 0.05). LV end-diastolic dimension (LVEDD) was significantly lower in CHF rats treated with GH-BAM than in CHF rats treated with GFP-BAM (P < 0.05). The levels of serum GH and IGF-1 were increased significantly in both CHF and sham rats treated with GH-BAM. The level of serum TNF-alpha decreased more significantly in the CHF treatment group than in the CHF control group.


CONCLUSIONS
rhGH significantly improves LV function and prevents cardiac remodeling in rats with CHF. Genetically modified tissue-engineered bioartificial muscle provides a method delivering recombinant protein for the treatment of heart failure.
Rong
Shu-ling
SL
Department of Cardiology, Heping Hospital, Changzhi Medical College, Changzhi, Shanxi 046000, China.
Wang
Yong-jin
YJ
Wang
Xiao-lin
XL
Lu
Yong-xin
YX
Chang
Chao
C
Wang
Feng-zhi
FZ
Liu
Qi-yun
QY
Liu
Xiang-yang
XY
Gao
Yan-zhang
YZ
Mi
Shao-hua
SH
D000818:Animals; D021522:Bioartificial Organs; D004452:Echocardiography; D006333:Heart Failure / Q000628:therapy; D019382:Human Growth Hormone / Q000008:administration & dosage*; D032448:Myoblasts, Skeletal / Q000378:metabolism*; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage; D023822:Tissue Engineering; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D016277:Ventricular Function, Left
D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D019382:Human Growth Hormone