Electroporation of Plasmid DNA into Mouse Skeletal Muscle

Summary

Electroporation of plasmid DNA into skeletal muscle is a viable method to modulate gene expression without compromising muscle contractility in mice.

Abstract

Transient gene expression modulation in murine skeletal muscle by plasmid electroporation is a useful tool for assessing normal and pathological physiology. Overexpression or knockdown of target genes enables investigators to manipulate individual molecular events and, thus, better understand the mechanisms that impact muscle mass, muscle metabolism, and contractility. In addition, electroporation of DNA plasmids that encode fluorescent tags allows investigators to measure changes in subcellular localization of proteins in skeletal muscle in vivo. A key functional assessment of skeletal muscle includes the measurement of muscle contractility. In this protocol, we demonstrate that whole muscle contractility studies are still possible after plasmid DNA injection, electroporation, and gene expression modulation. The goal of this instructional procedure is to demonstrate the step-by-step method of DNA plasmid electroporation into mouse skeletal muscle to facilitate uptake and expression in the myofibers of the tibialis anterior and extensor digitorum longus muscles, as well as to demonstrate that skeletal muscle contractility is not compromised by injection and electroporation.

Introduction

Plasmid DNA electroporation into skeletal muscle in vivo is an important tool for assessing changes in skeletal muscle physiology and molecular signaling by modulating gene expression in a variety of physiological and pathophysiological conditions^{1,2,3,4,5,6,7,8,9}. Experimental gene transfer into skeletal muscle was demonstrated as early as 1990 by Wolff et al.....

Protocol

All experiments using animals were performed at the Penn State College of Medicine, approved by Penn State University's Institutional Animal Care and Use Committee, and performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. 12-week-old female C57BL/6 mice were used for this procedure. All surgical tools were autoclaved for sterility prior to experimentation.

1. TA and EDL injection/electroporation preparation

Discussion

In vivo gene transfer in skeletal muscle enhanced by electroporation is a useful and relatively simple tool for modulating protein expression in muscle. We have shown the steps required to achieve efficient gene transfer in the EDL and TA muscles and demonstrated that contractility measurement of the EDL is viable following the procedure. This technique does not require more complicated viral vectors and allows for the comparison of transfected and non-transfected muscle fiber cross-sectional area in a single mu.......

Materials

Name	Company	Catalog Number	Comments
4-0 Nylon suture (non-absorbable)	Ethicon	662G	Suture to close skin incision
50µl Hamilton syringe	Hamilton	80501	microsyringe
C57BLl/6NHsd mice	Envigo	044	12 week-old female mice used for experimentation
Caliper Electrode	BTX	45-0102	1.0cm x 1.0cm stainless steel
Dynamic Muscle Control Data Acquisition/analysis	Aurora Scientific	605A	Software used for muscle contractility measurement and analysis
ECM 830 Electroporation System	BTX	45-0662	electroporator
EndoFree Plasmid Maxi Kit	Qiagen	12362	Plasmid purification kit
Extra Narrow Scissors	Fine Science Tools	14088-10	Scissors for blunt dissection
Force Transducer	Aurora Scientific	407A	To measure force from EDL
Micro-Masquito Hemastats	Fine Science Tools	13010-12	Hemastats for surturing
pcDNA3.1 mammalian expression vector	Fisher Scientific	V79020	Control Vector
pcDNA3-EGFP expression plasmid	Addgene	13031	Plasmid for GFP expression
Semken curved forceps	Fine Science Tools	11009-13	Forceps for surgery
Surgical blades stainless steel no. 10	Becton Dickinson	37 1210	Scalpel blades
Tissue-Tek O.C.T. media	VWR	25608-930	Freezing media for histology
Wheat Germ Agglutinin- Texas Red	Thermo-Fisher Scientific	W21405	Membrane staining for muscle cross section