Delaying denervated skeletal muscle atrophy in mice

Abstract

Objective To explore the effect of delaying atrophy of mice denervated skeletal muscles by lentivirus mediated gene transfer of cardiotrophin-1. Methods Thirty-six Swiss mice were randomly divided into experimental group and control group, with 18 each. A model of gastrocnemius muscle denervation atrophy was established at the right lower limb by transecting the tibial nerve. Deaervated gastrocnemius muscles of the experimental group and control group were administered with 20 μl ( 108 TU/ml) of recombinant lentivirus vector carrying CT-1 eDNA and with 20 μl of Lenti-GFP solution respectively. Two and 4 weeks following the transfection, 3 mice each were checked for transection efficacy by observing expression of green fluorescent protein (GFP) under fluorescent microscope. Westem blot assays were done to validate the expression of CT-1.Twitch tension and tetanie tension, muzzle wet weight preservation rate, muscle fiber cross-sectional area and ultrastruture of the denervated muscles were measured and observed in 6 mice at each timepoint to evaluate the extent of muscle atrophy. Results Strong GFP expression was observed in the gastrocnemius muscles of both groups at 2 and 4 weeks following lentivirus transfeetion. Westem blot showed significantly inereaticl expression of CT-1 in the experimental group compared with the control group ( P < 0.01 ). Two weeks after transfection,twitch tension and tetanic tension, muscle wet weight preservation rate and muscle fiber cross-sectional area of the denervated muscles in the experimental group were (47.61 ± 6.25) %, (56.08 ± 5.47) %, (63.02 ± 5.23) %and (1372.42+ 149.73)μm2 respectively, being significantly higher than those in the control group, which were (27.23±5.06)%,(30.78±4.67)%,(52.41±4.98)%and(1147.28±128.67)μm2 respectively(all P <0.01).At 4 weeks.the above-mendoned parameters were(33.13±4.76)%,(36.59 4-5.67)%.(51.46-±5.36)%,and(1209.12±142.57)μm2 respectively in the experimental group,being significantly greater than these in the control group which were(16.40±5.48)%,(15.35±4.08)%,(39.15±6.12)%and (989.45 4-136.12)μm2 respectively(all P<0.01).Dilation of the sareoplasmic refieulum of denervated muscles in the experimental group wss markedly alleviated.Conclusion Lentivirus mediated gene therapy can aehieve high transection efficacy.CT-1 gene tmnsfeefion call produce llighly egieient and sustained CT-1 secretion in vivo and delay denervation indueed skeletal muscle atrophy for at least 4 weeks. Key words: ]Muscular atrophy; Denervation; Cardiotrophin-1