MRC-5 Cells: Human Fetal Lung Fibroblasts in Viral Research

MRC-5 is a human diploid cell line widely used in producing viral vaccines, i.e., hepatitis A, polio, and rabies. It is also employed in the biomedical field to study viral infections and diseases. Besides, it is considered a valuable tool for drug screening and testing. This comprehensive article contains all the essential information about the MRC-5 human diploid cell line that can assist you in your work. Particularly, it will discuss:

General characteristics and origin of MRC-5 cells
Culturing information about MRC-5 cell line
MRC-5 cell line: Advantages & Limitations
Applications of MRC-5 cells in research
Publications on MRC-5 cell line
Resources for MRC-5 cell line: Protocols, Videos, and More

1. General characteristics and origin of MRC-5 cells

The applicability of a cell line in your research depends on its origin and general characteristics. This section of the article is all about MRC-5 fibroblast characteristics and origin. Here, you will learn: What are MRC-5 primary cells? What is the origin of MRC-5 cell line? What is MRC-5 morphology?

MRC-5, a normal human cell line, was developed in 1996 by J.P. Jacobs from the lung tissue of a Caucasian male fetus (14-week-old).
These are fibroblast-like cells.
The diameter of the MRC-5 lung cell is 18 μm.
MRC-5 possesses a normal diploid cell karyotype. The modal chromosome number for this normal human cell line is 46.

What are MRC-5 and WI-38 cells?

Both WI-38 and MRC-5 are normal human diploid cell lines. They were developed from two aborted fetuses in 1962 and 1996 [1]. MRC-5 and WI-38 are used for producing vaccines against several viral diseases. Some MRC-5 and WI-38 vaccines include rubella, varicella, hepatitis A, and rabies vaccines [2].

Scientist researching viral cells and antivirus in the pharmaceutical lab, examining cell proteins and samples with modern medical technologies.

2. Culturing information about MRC-5 cell line

Knowing the culturing information of a cell line can significantly ease your work with it. This article will cover all the key points for culturing the MRC-5. You will know: What is the MRC-5 doubling time? What are the culture conditions of MRC-5 fibroblasts? How do you culture MRC-5 human diploid cells?

Key Points for Culturing MRC-5 Cells

Doubling Time:	The MRC-5 doubling time is approximately 45 hours. However, depending upon the provided culturing conditions, it may vary between 35 to 45 hours.
Adherent or in Suspension:	The MRC-5 is an adherent cell line.
Cell density:	MRC-5 cells are seeded at an optimal density of 1 x 10⁴ cells/cm². Adherent cells are washed with 1 x PBS and then incubated for 8 to 10 minutes after adding passaging solution Accutase. After cell detachment, media is added, and cells are centrifuged. The recovered cell pellet is resuspended in a growth medium, and cells are dispensed into new flasks for growth.
Growth Medium:	EMEM media is used to culture MRC-5 cells. It is supplemented with 10% fetal bovine serum, 2.2 g/L NaHCO3, 2 mM L-Glutamine, and EBSS (Earle's Balanced Salt Solution).
Growth Conditions:	Like other mammalian cell lines, MRC-5 cells are also cultured in a humidified incubator at 37°C with a continuous 5% CO2 supply.
Storage:	Frozen MRC-5 cells are stored in the vapour phase of liquid nitrogen or at below -150 degrees Celsius.
Freezing Process and Medium:	CM-1 or CM-ACF is good for freezing MRC-5 cells. Cells are frozen using a slow freezing method to protect their viability.
Thawing Process:	Frozen MRC-5 cells are thawed in a water bath at 37°C until a small clump of ice is left. Next, the thawed cells are added with the fresh culture medium and centrifuged. This help in removing freezing media elements. harvested cells are then resuspended and poured into new flasks for growth.
Biosafety Level:	Biosafety level 1 laboratory is required for handling and maintenance of MRC-5 cultures.

Adherent semi-confluent layer of MRC-5 cells at 10× and 20× magnification.

3. MRC-5 cell line: Advantages & Limitations

Similar to other cell lines, MRC-5 human diploid cells have many advantages and disadvantages. In this section, we will go through some notable ones that may help you decide its use in your research.

Advantages

The main advantages of MRC-5 cells are:

Human-derived normal cell line	MRC-5 is a normal diploid cell line of human origin. It is a relevant cell model for studying human-specific diseases and mimics human cell physiology and responses, making it useful for biomedical and pharmaceutical research.
Susceptibility to viruses	MRC-5 fibroblast cells are highly susceptible to certain human viruses. Therefore, they can be employed to study viral diseases and utilized in producing viral vaccines.

Limitations

The limitation associated with the MRC-5 cell line is:

Finite lifespan

MRC-5 human diploid cells have a finite lifespan and may undergo 42 to 46 population doublings before senescence starts. This limitation restricts their use in long-term laboratory experiments.

4. Applications of MRC-5 cells in research

MRC-5 offers several research applications in the biomedical field. Some of the key research applications of the MRC-5 diploid cells include:

Vaccine production: MRC-5 cells are commonly used to produce certain vaccines against human-specific viral diseases such as measles, hepatitis A, rubella, and varicella (chickenpox). Several studies have been carried out on the production of viral vaccines using MRC-5 cells as substrate. Research has been conducted on the genetic manipulation of MRC-5 cells to enhance vaccine production. Moreover, MRC-5 cellular proteins are also targeted for effective vaccine production, such as, a study conducted in 2021 treated MRC-5 cells with interferon inhibitors and successfully suppressed its expression to increase pilot-scale production of Rabies virus titers [3].
Virology: MRC-5 cells serve as an invaluable tool in virology research. They are employed to study viral infections, replication, and the effects of potential antiviral drugs. Such as research conducted in 2019 investigated the antiviral mechanisms in MRC-5 human diploid cells against rabies viral infection. They found that exosomes, miR-423-5p, and the interferon (type I) signalling pathway may target for enhancing the rabies vaccine production in MRC-5 cells [4].

5. Publications on MRC-5 cell line

This section of the article will cover a few interesting research publications featuring the MRC-5 fibroblasts.

Determination of porcine circovirus in human diploid 2BS and MRC-5 cells for vaccine production

This study was published in the Chinese Journal of Biologicals in 2019. Herein, the researchers examined the human diploid cell lines 2BS and MRC-5 for porcine circovirus I and II.

Knockdown of circ-UQCRC2 ameliorated lipopolysaccharide-induced injury in MRC-5 cells by the miR-326/PDCD4/NF-κB pathway

This article published in International Immunopharmacology (2021) proposed that suppression of circular RNA, i.e., circ-UQCRC2 in lipopolysaccharide treated MRC-5 cell line improved cell injury via regulation of miR-326/PDCD4/NF-κB cascade.

Kurarinone inhibits HCoV-OC43 infection by impairing the virus-induced autophagic flux in MRC-5 human lung cells

This study in the Journal of clinical medicine (2020) explored the therapeutic potential of kurarinone, a prenylated flavanone, against human coronavirus HCoV-OC43 using MRC-5 cells.

Auraptene Has Antiviral Activity against Human Coronavirus OC43 in MRC-5 Cells

This publication in Nutrients, 2023, proposed the antiviral properties of auraptene (7-geranyloxycoumarin) against coronavirus HCoV-OC43 utilizing the MRC-5 human diploid cells.

The Effects of Resveratrol-Rich Extracts of Vitis vinifera Pruning Waste on HeLa, MCF-7 and MRC-5 Cells: Apoptosis, Autophagia and Necrosis Interplay

This study in Pharmaceutics (2022) investigated the potential therapeutic effects of Resveratrol-Rich Extracts of Vitis vinifera in three human cell lines: MRC-5 human cancer cell line Hela and MCF7.

6. Resources for MRC-5 cell line: Protocols, Videos, and More

The following are a few resources available on MRC-5 cells.

MRC-5 transfection: This video tutorial is about in vitro transfection in the MRC-5 cell line. It may help you learn the transfection protocol effectively.

The following link contains the MRC-5 cell culture protocol.

MRC-5 subcultivation: This link will provide a protocol for passaging or sub-cultivating MRC-5 cells. Protocol for cell thawing is also mentioned.
MRC-5 cell culture protocol: This document may help you learn the protocol for subculturing of MRC-5 cells.

References

McKenna, K.C., Use of Aborted Fetal Tissue in Vaccines and Medical Research Obscures the Value of All Human Life. Linacre Q, 2018. 85(1): p. 13-17.
Jordan, I. and V. Sandig, Matrix and backstage: cellular substrates for viral vaccines. Viruses, 2014. 6(4): p. 1672-700.
Yang, X., et al., Interferon Inhibition Enhances the Pilot-Scale Production of Rabies Virus in Human Diploid MRC-5 Cells. Viruses, 2021. 14(1): p. 49.
Wang, J., et al., Exosome-mediated delivery of inducible miR-423-5p enhances resistance of MRC-5 cells to rabies virus infection. International Journal of Molecular Sciences, 2019. 20(7): p. 1537.