Analysis of Human Vastus Lateralis Skeletal Muscle Biopsy Samples Changes in Response to High and Low Inflation Pressures during Peristaltic Pulse External Pneumatic Compression Via Transcriptome‐wide RNA Sequencing

Abstract

We employed next generation RNA sequencing (RNA‐seq) technology to determine the impact of peristaltic pulse external pneumatic compression (EPC) at high and low target inflation pressures on global gene expression in human vastus lateralis skeletal muscle biopsy samples.MethodsEighteen (N=18) apparently healthy male subjects participated in this study and were randomly assigned to one of three groups: 1) sham (n=6), 2) EPC with target inflation pressures of 30 mmHg (n=6) and 3) EPC with target inflation pressures of 70–80 mmHg (n=6). Daily treatment with sham or EPC was given for 7 consecutive days with each treatment lasting 1 h. Vastus lateralis skeletal muscle biopsy samples were harvested at baseline (48 hours before the first treatment; T1), 1 h following the first treatment (T2), and 24 hours following the last (7th) treatment (T3). 3,613 annotated genes with an RPKM value of ≥ 1.0 were selected for analysis. Change from baseline (T1) in gene expression was analyzed via paired comparisons within each group (i.e. T2 vs. T1 and T3 vs. T1). The 3,613 genes were then further filtered to include only those that had a fold‐change (FC) of ≥ 1.5 and a paired t‐test value of <0.01.ResultsFor the sham condition, only 2 genes at T2 (SF3B5, FIS1) and 1 gene at T1 (LYPLA2) were identified as being significantly altered compared to baseline with time. For the 30 mmHg EPC condition, 9 genes were found to be significantly upregulated at T2 and 39 genes were found to be significantly upregulated at T3 compared to baseline. Two of these genes were significantly upregulated at both T2 and T3 (ARRDC2 and DYNLL2). Only one gene was found to be significantly downregulated compared to baseline in the 30 mmHg EPC group (TIMM10) and this was observed at T3. For the 70–80 mmHg EPC condition, 2 genes were found to be significantly upregulated (HBA1, HBA2) and 21 genes were found to be significantly downregulated at T2 compared to baseline. At T3, only 1 gene was found to be significantly altered (downregulation of DNAJB5) in the 70–80 mmHg EPC group. Interestingly, VEGFA was found to be differentially regulated as its expression was significantly upregulated with 30 mmHg EPC at T3 and significantly downregulated with 70–80 mmHg EPC at T3. Follow up analyses respective to gene clusters of interest are presented herein.ConclusionsIn summary, a more dynamic alteration of skeletal muscle gene expression was observed with a lower (i.e. 30 mmHg) EPC target inflation pressure, particularly after 7 consecutive days of treatment. Moreover, altered genes tended to be upregulated with 30 mmHg EPC whereas genes tended to be downregulated with 70 mmHg.Support or Funding InformationThe authors would like to thank NormaTec (Newton Center, MA) for their partial financial support (50%) of this project through a contract awarded to J.S.M.