An Efficient Transgenesis Approach for Gene Delivery in the Mouse Embryonic Heart

Summary

This protocol presents a detailed methodological framework for electroporation-based transgenesis of cardiac cells in developing mouse hearts. The video assets provided here will facilitate learning of this versatile technique.

Abstract

The mammalian heart is a complex organ formed during development via highly diverse populations of progenitor cells. The origin, timing of recruitment, and fate of these progenitors are vital for the proper development of this organ. The molecular mechanisms that govern the morphogenesis of the heart are essential for understanding the pathogenesis of congenital heart diseases and embryonic cardiac regeneration. Classical approaches to investigate these mechanisms employed the generation of transgenic mice to assess the function of specific genes during cardiac development. However, mouse transgenesis is a complex, time-consuming process that often cannot be performed to assess the role of specific genes during heart development. To address this, we have developed a protocol for efficient electroporation and culture of mouse embryonic hearts, enabling transient transgenesis to rapidly assess the effect of gain- or loss-of-function of genes involved in cardiac development. Using this methodology, we successfully overexpressed Meis1 in the embryonic heart, with a preference for epicardial cell transfection, demonstrating the capabilities of the technique.

Introduction

The heart is the first organ formed during embryonic development. This process involves the spatiotemporal coordination of various populations of progenitor cells from distinct areas of the embryo. All this occurs while the developing heart continues to beat and function, emphasizing the remarkable coordination required for its formation^1,2,3. Given the crucial role of the heart, tight regulation at the cellular and molecular levels is essential for its proper formation^4,5. Identifying the mechanisms that control hear....

Protocol

All animal procedures were approved by the CNIC Animal Experimentation Ethics Committee and conformed to current legislation, including EU Directive 2010/63EU and Recommendation 2007/526/EC, as enforced by Spanish Law under Real Decreto 53/2013. For this protocol, female wild-type CD-1 mice aged 15-21 weeks were employed. Details regarding the animals, reagents, and equipment used are listed in the Table of Materials.

1. Plasmid and tool preparation

Discussion

Overall, the methodology described here offers a robust framework for expressing transgenic constructs in the developing epicardium (Figure 4B), as demonstrated by Meis1 overexpression (Figure 4C). With the appropriate constructs, this protocol can be used to transiently assess the impact of either gain-of-function (GOF) or loss-of-function (LOF) of a specific gene. LOF can be implemented into the technique by transfecting a plasmid targeting a candidate gene th.......

Materials

Name	Company	Catalog Number	Comments
#55 Forceps	Dumont	11295-51
12-well Clear Flat Bottom Multiwell Cell Culture Plate	BD Falcon	353043
35 mm vise table	Grandado	SKU 8798771617573
40 µm Cell Strainer	Fischer Scientific	08-771-1
50 mL tubes	BD Falcon	352070
70 µm Cell Strainer	Corning	CLS431751
Anti-GFP Policlonal Antibody	Invitrogen	A10262	1:1000 dilution used
Anti-Myosin 4 (MF20) Monoclonal Antibody	Invitrogen	14-6503-82	1:500 dilution used
CD1 Wild Type mice			Provided by Animalary Unit (CNIC)
Cleaved Caspase-3 (Asp175) Antibody	Cell Signalling Technologies	9661	1:400 dilution used
DAPI	Cell Signalling Technologies	4083	1:1000 dilution used
Dispase/collagenase	Roche	10269638001
Distilled water
DMEM - Dulbecco's Modified Eagle Medium	Gibco	10313021
Fetal Bovine Serum	Invitrogen	10438-026
Heracell 150i CO2 Incubator	Thermo Scientific	51032720
Leica Stereoscopic Microscope S8AP0	Leica	11524102
Liberase	Roche	5401119001
Micropipette Puller Model P-97	Sutter Instrument	SU-P-97
pCAG expression plasmid	Addgene	#89689
Penicillin-streptomycin	Invitrogen	15070-063
Petri dishes 35 × 10 mm	BD Falcon	351008
Petri dishes 60 × 15 mm	BD Falcon	353002
Phenol Red	Merck	P3532
Pipette tips			Reused from old laboratory equipment
Rat Serum culture embryo, male rats SPRAGUE DAWLEY RjHan SD	Janvier Labs	9979
Recombinant anti-Wilms Tumor Protein 1 (WT1) Antibody	Abcam	ab89901	1:300 dilution used
Square Wave Electroporator CUY21SC	Nepa Gene	CUY664-10X15
Sterile PBS			Provided and autoclaved by technical unit
Sucrose	Millipore	84100
Tweezer electrodes with variable gap	Nepa Gene	CUY650P5