Generating Self-Assembling Human Heart Organoids Derived from Pluripotent Stem Cells

Summary

Here, we describe a protocol to create developmentally relevant human heart organoids (hHOs) efficiently using human pluripotent stem cells by self-organization. The protocol relies on the sequential activation of developmental cues and produces highly complex, functionally relevant human heart tissues.

Abstract

The ability to study human cardiac development in health and disease is highly limited by the capacity to model the complexity of the human heart in vitro. Developing more efficient organ-like platforms that can model complex in vivo phenotypes, such as organoids and organs-on-a-chip, will enhance the ability to study human heart development and disease. This paper describes a protocol to generate highly complex human heart organoids (hHOs) by self-organization using human pluripotent stem cells and stepwise developmental pathway activation using small molecule inhibitors. Embryoid bodies (EBs) are generated in a 96-well plate with round-bottom, ultra-low attachment wells, facilitating suspension culture of individualized constructs.

The EBs undergo differentiation into hHOs by a three-step Wnt signaling modulation strategy, which involves an initial Wnt pathway activation to induce cardiac mesoderm fate, a second step of Wnt inhibition to create definitive cardiac lineages, and a third Wnt activation step to induce proepicardial organ tissues. These steps, carried out in a 96-well format, are highly efficient, reproducible, and produce large amounts of organoids per run. Analysis by immunofluorescence imaging from day 3 to day 11 of differentiation reveals first and second heart field specifications and highly complex tissues inside hHOs at day 15, including myocardial tissue with regions of atrial and ventricular cardiomyocytes, as well as internal chambers lined with endocardial tissue. The organoids also exhibit an intricate vascular network throughout the structure and an external lining of epicardial tissue. From a functional standpoint, hHOs beat robustly and present normal calcium activity as determined by Fluo-4 live imaging. Overall, this protocol constitutes a solid platform for in vitro studies in human organ-like cardiac tissues.

Introduction

Congenital heart defects (CHDs) are the most common type of congenital defect in humans and affect approximately 1% of all live births^1,2,3. Under most circumstances, the reasons for CHDs remain unknown. The ability to create human heart models in the lab that closely resemble the developing human heart constitutes a significant step forward to directly study the underlying causes of CHDs in humans rather than in surrogate animal models.

The epitome of laboratory-grown tissue models are organoids, 3D cell constructs that resemble an organ of intere....

Protocol

1. hPSC culture and maintenance

NOTE: The human induced PSCs (hiPSCs) or human embryonic stem cells (hESCs) need to be cultured for at least 2 consecutive passages after thawing before being used to generate EBs for differentiation or further cryopreservation. hPSCs are cultured in PSC medium (see the Table of Materials) on basement-membrane-extracellular matrix (BM-ECM)-coated 6-well culture plates. When performing medium changes on hPSCs in 6-well plates, add the medium direct.......

Discussion

Recent advances in human stem cell-derived cardiomyocytes and other cells of cardiac origin have been used to model human heart development^22,24,25 and disease^26,27,28 and as tools to screen therapeutics^29,30 and toxic agents^31,

Materials

Name	Company	Catalog Number	Comments
Antibodies
Alexa Fluor 488 Donkey anti- mouse	Invitrogen	A-21202	1:200
Alexa Fluor 488 Donkey anti- rabbit	Invitrogen	A-21206	1:200
Alexa Fluor 594 Donkey anti- mouse	Invitrogen	A-21203	1:200
Alexa Fluor 594 Donkey anti- rabbit	Invitrogen	A-21207	1:200
Alexa Fluor 647 Donkey anti- goat	Invitrogen	A32849	1:200
HAND1	Abcam	ab196622	Rabbit; 1:200
HAND2	Abcam	ab200040	Rabbit; 1:200
NFAT2	Abcam	ab25916	Rabbit; 1:100
PECAM1	DSHB	P2B1	Rabbit; 1:50
TNNT2	Abcam	ab8295	Mouse; 1:200
THY1	Abcam	ab133350	Rabbit; 1:200
TJP1	Invitrogen	PA5-19090	Goat; 1:250
VIM	Abcam	ab11256	Goat; 1:250
WT1	Abcam	ab89901	Rabbit; 1:200
Media and Reagents
Accutase	Innovative Cell Technologies	NC9464543	cell dissociation reagent
Activin A	R&D Systems	338AC010
B-27 Supplement (Minus Insulin)	Gibco	A1895601	insulin-free cell culture supplement
B-27 Supplement	Gibco	17504-044	cell culture supplement
BMP-4	Gibco	PHC9534
Bovine Serum Albumin	Bioworld	50253966
CHIR-99021	Selleck	442310
D-(-)-Fructose	Millipore Sigma	F0127
DAPI	Thermo Scientific	62248	1:1000
Dimethyl Sulfoxide	Millipore Sigma	D2650
DMEM/F12	Gibco	10566016
Essential 8 Flex Medium Kit	Gibco	A2858501	pluripotent stem cell (PSC) medium containing 1% penicillin-streptomycin
Fluo4-AM	Invitrogen	F14201
Glycerol	Millipore Sigma	G5516
Glycine	Millipore Sigma	410225
Matrigel GFR	Corning	CB40230	Basement membrane extracellular matrix (BM-ECM)
Normal Donkey Serum	Millipore Sigma	S30-100mL
Paraformaldehyde	MP Biomedicals	IC15014601	Powder dissolved in PBS Buffer – use at 4%
Penicillin-Streptomycin	Gibco	15140122
Phosphate Buffer Solution	Gibco	10010049
Phosphate Buffer Solution (10x)	Gibco	70011044
Polybead Microspheres	Polysciences, Inc.	73155	90 µm
ReLeSR	Stem Cell Technologies	NC0729236	dissociation reagent for hPSCs
RPMI 1640	Gibco	11875093
Thiazovivin	Millipore Sigma	SML1045
Triton X-100	Millipore Sigma	T8787
Trypan Blue Solution	Gibco	1525006
VECTASHIELD Vibrance Antifade Mounting Medium	Vector Laboratories	H170010
WNT-C59	Selleck	NC0710557
Other
1.5 mL Microcentrifuge Tubes	Fisher Scientific	02682002
15 mL Falcon Tubes	Fisher Scientific	1495970C
2 mL Cryogenic Vials	Corning	13-700-500
50 mL Reagent Reservoirs	Fisherbrand	13681502
6-Well Flat Bottom Cell Culture Plates	Corning	0720083
8 Well chambered cover Glass with #1.5 high performance cover glass	Cellvis	C8-1.5H-N
96-well Clear Ultra Low Attachment Microplates	Costar	07201680
ImageJ	NIH		Image processing software
Kimwipes	Kimberly-Clark Professional	06-666	laboratory wipes
Micro Cover Glass	VWR	48393-241	24 x 50 mm No. 1.5
Microscope Slides	Fisherbrand	1255015
Moxi Cell Counter	Orflo Technologies	MXZ001
Moxi Z Cell Count Cassette – Type M	Orflo Technologies	MXC001
Multichannel Pipettes	Fisherbrand	FBE1200300	30-300 µL
Olympus cellVivo	Olympus		For Caclium Imaging, analysis with Imagej
Sorvall Legend X1 Centrifuge	ThermoFisher Scientific	75004261
Thermoshaker	ThermoFisher Scientific	13-687-711PM
Top Coat Nail Varish	Seche Vite		Can purchase from any supermarket