Immunocompetent Alveolus-on-Chip Model for Studying Alveolar Mucosal Immune Responses

Summary

Lung-on-chip models surpass traditional 2D cultures by mimicking the air-liquid interface and endothelial cell perfusion, simulating blood flow and nutrient exchange crucial for lung physiology studies. This enhances lung research relevance, offering a dynamic, physiologically accurate environment to advance the understanding and treatment of respiratory infections.

Abstract

We introduce an advanced immunocompetent lung-on-chip model designed to replicate the human alveolar structure and function. This innovative model employs a microfluidic-perfused biochip that supports an air-liquid interface mimicking the environment in the human alveoli. Tissue engineering is used to integrate key cellular components, including endothelial cells, macrophages, and epithelial cells, to create a representative tissue model of the alveolus. The model facilitates in-depth examinations of the mucosal immune responses to various pathogens, including viruses, bacteria, and fungi, thereby advancing our understanding of lung immunity. The primary goal of this protocol is to provide details for establishing this alveolus-on-chip model as a robust in vitro platform for infection studies, enabling researchers to closely observe and analyze the complex interactions between pathogens and the host's immune system within the pulmonary environment. This is achieved through the application of microfluidic-based techniques to simulate key physiological conditions of the human alveoli, including blood flow and biomechanical stimulation of endothelial cells, alongside maintaining an air-liquid interface crucial for the realistic exposure of epithelial cells to air. The model system is compatible with a range of standardized assays, such as immunofluorescence staining, cytokine profiling, and colony-forming unit (CFU)/plaque analysis, allowing for comprehensive insights into immune dynamics during infection. The Alveolus-on-chip is composed of essential cell types, including human distal lung epithelial cells (H441) and human umbilical vein endothelial cells (HUVECs) separated by porous polyethylene terephthalate (PET) membranes, with primary monocyte-derived macrophages strategically positioned between the epithelial and endothelial layers. The tissue model enhances the ability to dissect and analyze the nuanced factors involved in pulmonary immune responses in vitro. As a valuable tool, it should contribute to the advancement of lung research, providing a more accurate and dynamic in vitro model for studying the pathogenesis of respiratory infections and testing potential therapeutic interventions.

Introduction

The human lung has a remarkable role in respiration and immune defense, with complex interactions between the immune responses of the alveolar mucosa¹. The ability of the alveoli to create an efficient immune response is vital for preventing lung infections and securing pulmonary health. Since the lungs are constantly exposed to a wide range of potential risks, including bacteria, viruses, fungi, allergies, and particulate matter, understanding the complexities of alveolar mucosal immune responses is critical for discovering the mechanisms behind respiratory infections, inflammatory disorders and treating pulmonary diseases

Protocol

HUVEC cells are isolated from umbilical cords and used up to passage 4. Primary monocytes are isolated from healthy donors from whole blood. The study was approved by the ethics committee of the Jena University Hospital, Jena, Germany (3939-12/13). According to the Declaration of Helsinki, all individuals donating cells for the study gave their informed consent.

1. Day 1: Preparation of the biochip

1. The biochips are available in different sizes and models. For exper.......

Discussion

The alveolus-on-chip model represents a multilayered tissue model of the human alveolus, integrating essential cell types of the lower respiratory tract, including lung epithelial cells, endothelial cells, and macrophages, cultured in an organotypic arrangement at an ALI with medium perfusion of the endothelial lining. Cells of different layers express specific cell marker proteins such as E-cadherin, a calcium-dependent adhesion molecule of lung epithelial cells, which is central in establishing intercellular epithelial.......

Materials

Name	Company	Catalog Number	Comments
Consumables
Cellcounting chamber slides (Countess)	Invitrogen	C10283
Cell culture Multiwell Plates, 24 Well, steril	Greiner Bio-One	662 160
Cell culture Multiwell Plates, 6 Well, steril	Greiner Bio-One	657 160
Coverslips (24x40mm; #1.5)	Menzel-Gläser	15747592
Eco wipes	Dr. Schuhmacher	00-915-REW10003-01
Eppies 2.0	Sarstedt	72.691
Eppis 0.5	Sarstedt	72.699
Eppis 1.5	Sarstedt	72.690.001
Falcons 15mL	Greiner Bio-One	188 271-TRI
Falcons 50mL	Greiner Bio-One	227 261-TRI
Gauze swab	Noba	PZN 2417767
Gloves Nitril 3000	Meditrade	1280
Microscope slides	Menzel-Gläser	AAAA000001##12E
Multiwell Plates 24 Well, sterile	Greiner Bio-One	662 160
Pasteur pipettes (glass) 150mm	Assistent	40567001
Pasteur pipettes (glass) 230mm	Assistent	40567002
Round-bottom tubes (PS, 5mL)	Falcon	352052
Safety-Multifly-Set, 20G, 200mm	Sarstedt	85.1637.235
Scalpels	Dahlhausen	11.000.00.715
Serological pipettes 10mL	Greiner Bio-One	607 160-TRI
Serological pipettes 25mL	Greiner Bio-One	760 160-TRI
Serological pipettes 2mL	Greiner Bio-One	710 160-TRI
Serological pipettes 50mL	Greiner Bio-One	768 160-TRI
Serological pipettes 5mL	Greiner Bio-One	606 160-TRI
S-Monovette, 7,5ml Z-Gel	Sarstedt	1.1602
S-Monovette, 9,0ml K3E	Sarstedt	02.1066.001
Softasept N	Braun	3887138
T25 flask	Greiner Bio-One	690 960
Tips sterile 10µL	Greiner Bio-One	771 261
Tips sterile 1250µL	Greiner Bio-One	750 261
Tips sterile 300µL	Greiner Bio-One	738 261
Tips unsterile 10µL	Greiner Bio-One	765 290
Tips unsterile 1000µL	Greiner Bio-One	739 291
Tips unsterile 200µL	Greiner Bio-One	686 290
Tweezers (Präzisionspinzette DUMONT abgewinkelt Inox08, 5/45, 0,06 mm)	Roth	K343.1
Chemicals
Descosept AF	Dr. Schuhmacher	N-20338
Ethanol 96%	Nordbrand-Nordhausen	410
Fluorescein isothiocyanate (FITC)-dextran (3-5kDa)	Sigma Aldrich	FD4-100MG
Fluorescent Mounting Medium	Dako	S3023
Methanol	VWR	20847.295
Saponin	Fluka	47036
Tergazyme	Alconox	1304-1
Cell culture
Collagen IV	Sigma-Aldrich	C5533-5MG
Dexametason	Sigma-Aldrich	D4902
DPBS (-/-)	Lonza	BE17-516F
DPBS (+/+)	Lonza	BE17-513F
EDTA solution	Sigma-Aldrich	E788S
Endothelial Cell Growth Medium	Promocell	C-22020
Endothelial Cell Growth Medium supplement mix	Promocell	C-39225
Fetal bovine Serum	Sigma-Aldrich	E2129-10g
H441	ATCC
Human recombinant GM-CSF	Peprotech	300-30
Lidocain	Sigma-Aldrich	L5647-15G
Penicillin-Streptomycin (10,000 U/mL)	Gibco	15140-122 /-163
RPMI	Gibco	72400047
Trypane blue stain 0.4%	Invitrogen	T10282
Trypsin	Gibco	15090-046
Primary antibodies
Cadherin-5 / VE-Cadherin (goat)	BD	610252
CD68 (rabbit)	CellSignaling	76437
E-Cadherin (goat)	R&D	AF748
SP-A (mouse)	Abcam	ab51891
Secondary antibodies
AF488 (donkey anti mouse)	Invitrogen	R37114
AF647 (donkey anti mouse)	invitrogen	A31571
AF647 (donkey anti rabbit)	Invitrogen	A31573
Cy3 (donkey anti goat)	jackson research	705-165-147
DAPI (4',6-Diamidino-2-Phenylindole, Dilactate)	Invitrogen	D3571
Microfluidic
Chip	Dynamic 42	BC002
Male Luer Lock (small)	ChipShop	09-0503-0270-09
Male mini luer plugs, row of four,PP, green	Microfluidic chipshop	09-0558-0336-11
Male mini luer plugs, row of four,PP, opaque	Microfluidic chipshop	09-0556-0336-09
Male mini luer plugs, row of four,PP, red	Microfluidic chipshop	09-0557-0336-10
Plugs	Cole Parmer	GZ-45555-56
Reservoir 4.5mL	ChipShop	16-0613-0233-09
Tubing	Dynamic 42	ST001
Equipment
Autoclave	Tuttnauer	5075 ELV
Centrifuge	Eppendorf	5424
CO2 Incubator	Heracell	150i
Countess automated cell counter	Invitrogen	C10227
Flowcytometer	BD	FACS Canto II
Freezer (-20 °C)	Liebherr	LCexv 4010
Freezer (-80 °C)	Heraeus	Herafreeze HFU 686
Fridge	Liebherr	LCexv 4010
Heraeus Multifuge	Thermo Scientific	X3R
Microscope	Leica	DM IL LED
Orbital shaker	Heidolph	Reax2000
Peristaltic pump	REGLO Digital MS-4/12	ISM597D
Pipettes 10µL	Eppendorf Research plus	3123000020
Pipettes 100µL	Eppendorf Research plus	3123000047
Pipettes 1000µL	Eppendorf Research plus	3123000063
Pipettes 2.5µL	Eppendorf Research plus	3123000012
Pipettes 20µL	Eppendorf Research plus	3123000039
Pipettes 200µL	Eppendorf Research plus	3123000055
Scale	Sartorius	6101
Scale	Sartorius	TE1245
Sterile bench	Kojair	Biowizard SL-130
Waterbath	Julabo	SW-20C
Fluorescence Microscope Setup
Apotome.2	Zeiss
Illumination device	Zeiss	HXP 120 C
Microscope	Zeiss	Axio Observer 5
Optical Sectioning	Zeiss	ApoTome
Power Supply Microscope	Zeiss	Eplax Vp232
Software
ZEN Blue Edition	Zeiss