Local Applications of Myostatin-siRNA with Atelocollagen Increase Skeletal Muscle Mass and Recovery of Muscle Function

Abstract

BackgroundGrowing evidence suggests that small-interfering RNA (siRNA) can promote gene silencing in mammalian cells without induction of interferon synthesis or nonspecific gene suppression. Recently, a number of highly specific siRNAs targeted against disease-causing or disease-promoting genes have been developed. In this study, we evaluate the effectiveness of atelocollagen (ATCOL)-mediated application of siRNA targeting myostatin (Mst), a negative regulator of skeletal muscle growth, into skeletal muscles of muscular dystrophy model mice.Methods and FindingsWe injected a nanoparticle complex containing myostatin-siRNA and ATCOL (Mst-siRNA/ATCOL) into the masseter muscles of mutant caveolin-3 transgenic (mCAV-3Tg) mice, an animal model for muscular dystrophy. Scrambled (scr) -siRNA/ATCOL complex was injected into the contralateral muscles as a control. Two weeks after injection, the masseter muscles were dissected for histometric analyses. To investigate changes in masseter muscle activity by local administration of Mst-siRNA/ATCOL complex, mouse masseter electromyography (EMG) was measured throughout the experimental period via telemetry. After local application of the Mst-siRNA/ATCOL complex, masseter muscles were enlarged, while no significant change was observed on the contralateral side. Histological analysis showed that myofibrils of masseter muscles treated with the Mst-siRNA/ATCOL complex were significantly larger than those of the control side. Real-time PCR analysis revealed a significant downregulation of Mst expression in the treated masseters of mCAV-3Tg mice. In addition, expression of myogenic transcription factors was upregulated in the Mst-siRNA-treated masseter muscle, while expression of adipogenic transcription factors was significantly downregulated. EMG results indicate that masseter muscle activity in mCAV-3Tg mice was increased by local administration of the Mst-siRNA/ATCOL complex.ConclusionThese data suggest local administration of Mst-siRNA/ATCOL complex could lead to skeletal muscle hypertrophy and recovery of motor disability in mCAV-3Tg mice. Therefore, ATCOL-mediated application of siRNA is a potential tool for therapeutic use in muscular atrophy diseases.

Retracted: Effectiveness of cationic liposome‐mediated local delivery of myostatin‐targeting small interfering RNA in vivo

“…We found that local and systemic administration of the myostatin‐targeting siRNA delivered by ATCOL led to marked stimulation of muscle growth in vivo within a few weeks (Kawakami et al . , ).…”

Co-Administration of Myostatin-Targeting siRNA and ActRIIB-Fc Fusion Protein Increases Masseter Muscle Mass and Fiber Size

“…ATCOL-based delivery of siRNA resulted in efficient inhibition of metastatic tumors in vivo (15,16). We have also reported that 2-wk treatment with ATCOL-based myostatin-targeting siRNA (MstnsiRNA/ATCOL) increased muscle mass and enhanced muscle activity (17)(18)(19). These findings suggest that the delivery of Mstn-siRNA/ATCOL into skeletal muscle is safe, efficient, and effective for augmentation of muscle structure and function.…”

“…Elevenweek-old C57BL/6 male mice were housed under a 12/12 h light/dark cycle and ambient temperature of 22˚C, and were provided with food and water ad libitum. On the basis of previous reports (12,(17)(18)(19)21), 10 M of Mstn-siRNA/ATCOL and 1 M of human ActRIIB-Fc fusion protein, purchased from Koken and R&D Systems Inc. (Minneapolis, MN), were used in this study. They were injected together into the left masseter muscles of the mice at 0 and 4 d. The control mice received injections of sterilized phosphate-buffered saline (PBS) into the left masseter muscles.…”

Technologies for controlled, local delivery of siRNA

“…siRNA against myostatin, a gene that impedes muscle growth, delivered at a dose of 0.5 nmols from atelocollagen nanoparticles was shown to increase muscle growth, size, and activity in a mouse model of muscular dystrophy 147, 148 . These results were achieved via a local injection into mouse masseter muscle; however, the proven impact of myostatin siRNA on muscle growth motivates its further exploration in controlled delivery depots to regenerate weak or otherwise compromised muscle tissue.…”