The Isolation and Culture of Primary Epicardial Cells Derived from Human Adult and Fetal Heart Specimens

Summary

The epicardium plays a crucial role in the development and repair of the heart by providing cells and growth factors to the myocardial wall. Here, we describe a method to culture human primary epicardial cells that enables the study and comparison of their developmental and adult characteristics.

Abstract

The epicardium, an epithelial cell layer covering the myocardium, has an essential role during cardiac development, as well as in the repair response of the heart after ischemic injury. When activated, epicardial cells undergo a process known as epithelial to mesenchymal transition (EMT) to provide cells to the regenerating myocardium. Furthermore, the epicardium contributes via secretion of essential paracrine factors. To fully appreciate the regenerative potential of the epicardium, a human cell model is required. Here we outline a novel cell culture model to derive primary epicardial derived cells (EPDCs) from human adult and fetal cardiac tissue. To isolate EPDCs, the epicardium is dissected from the outside of the heart specimen and processed into a single cell suspension. Next, EPDCs are plated and cultured in EPDC medium containing the ALK 5-kinase inhibitor SB431542 to maintain their epithelial phenotype. EMT is induced by stimulation with TGFβ. This method enables, for the first time, the study of the process of human epicardial EMT in a controlled setting, and facilitates gaining more insight in the secretome of EPDCs that may aid heart regeneration. Furthermore, this uniform approach allows for direct comparison of human adult and fetal epicardial behavior.

Introduction

The epicardium, a single-cell epithelial layer that envelopes the heart, is of vital importance for cardiac development and repair (reviewed in Smits et al.¹). Developmentally, the epicardium arises from the proepicardial organ, a small structure located at the base of the developing heart. Around developmental day E9.5 in mouse, and 4 weeks post-conception in human, cells start to migrate from this cauliflower structure and cover the developing myocardium². Once a single epithelial cell layer is formed, a portion of the epicardial cells undergoes epithelial to mesenchymal transition (EMT). During EMT, cell....

Protocol

All experiments with human tissue specimens were approved by the ethics committee of the Leiden University Medical Center and conforms to the Declaration of Helsinki. All steps are performed with sterile equipment in a cell culture flow cabinet.

1. Preparations

1. Prepare EPDC medium by mixing Dulbecco's modified Eagle's medium (DMEM low- glucose) and Medium 199 (M199) in a 1:1 ratio. Add 10% heat inactivated fetal bovine serum (FBS, heat inactivated for 25 min at 56 °C) and supplement with 100 U/mL penicillin and 100 mg/mL streptomycin. Pre-warm the EPDC medium in a 37 °C water bath.
2. Pre-warm Tryp....

Results

Here, we outline a straightforward protocol to isolate EPDCs from human adult and fetal cardiac tissue (Figure 1). This protocol takes advantage of the easily accessible location of the epicardium on the outside of the heart (Figure 1A). Staining of the heart auricle after dissection demonstrates that the WT1+ epicardium is removed while the underlying subepicardial extracellular matrix and myocardial tissue remain intact (

Discussion

Here we describe a detailed protocol to isolate and culture primary epicardial cells derived from human adult and fetal hearts. Extensive characterization of these cells has been previously published¹⁷. We have shown that both cell types can be maintained as epithelial cobblestone-like cells when cultured with the ALK5 kinase inhibitor SB431542. EMT is an integral part of epicardial activation in vivo during both development and the post-injury response. EMT can be studied using this meth.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Dulbecco’s modified Eagle’s medium + GlutaMAX	Gibco	21885-025
Medium 199	Gibco	31150-022
Fetal Bovine Serum	Gibco	10270-106
Trypsin 0.25%	Invitrogen	25200-056
Penicillin G sodium salt	Roth	HP48
Streptomycin sulphate	Roth	HP66
Trypsin 1:250 from bovine pancreas	Serva	37289
EDTA	Sigma	E4884
Gelatin from porcine skin	Sigma-Aldrich	G1890
Culture plates 6 well	Greiner bio-one	657160
Culture plates 12 well	Corning	3512
Culture plates 24 well	Greiner bio-one	662160
SB 431542	Tocris	1614
Dimethyl Sulfoxide (DMSO)	Merck	102931
100-1000µL Filtered Pipet Tips	Corning	4809
10-ml pipet	Greiner bio-one	607180
5-ml pipet	Greiner bio-one	606180
Cell culture dish 100/20 mm	Greiner bio-one	664160
PBS	Gibco	10010056	Or home-made and sterilized
Eppendorf tubes 1.5 mL	Eppendorf	0030120086
15-ml centrifuge tubes	Greiner bio-one	188271
50-ml centrifuge tubes	Greiner bio-one	227261
10 mL Syringe	Becton Dickinson	305959
Needles 19 Gauge	Becton Dickinson	301700
Needles 21 Gauge	Becton Dickinson	304432
EASYstrainer Cell Sieves, 100 µm	Greiner bio-one	542000
TGFβ3	R&D systems	243-B3
Monoclonal Anti-Actin, α-Smooth Muscle	Sigma	A2547
Anti-Mouse Alexa Fluor 555	Invitrogen	A31570
Alexa Fluor 488 Phalloidin	Invitrogen	A12379
Equipment
Name	Company	Catalog Number	Comments
Pipet P1,000	Gilson	F123602
Pipet controller	Integra	155 015
Stereomicroscope	Leica	M80
Inverted Light Microscope	Olympus	CK2
Centrifuge	Eppendorf	5702
Waterbath	GFL	1083