A relatively new experimental technique is allowing scientists to discover the internal effects of smoking on unborn babies

smoking1Image taken from tobaccocampaign.com


by Hayley Fryer

How would you feel if you saw a pregnant woman smoking?

It’s a thought-provoking question, and you probably had a strong automatic reaction to it. Smoking in general is now frowned upon in most social settings, but smoking during pregnancy is a particular social taboo.

In 2011 the Pregnancy Risk Assessment and Monitoring System (PRAMS) reported that approximately 45% of female smokers did not quit during pregnancy.

This figure may seem very high, as the negative implications of cigarettes on developing foetuses are widely reported. Some of these issues include premature births, birth defects such as cleft lip or cleft palate, and an increased chance of infant death.

Historically, it has been difficult to properly research the internal effects of smoking on human foetuses. Premature births and birth defects are easy to visualise externally, but the impacts on internal organs and structures are difficult to research due to ethical issues involved with experimenting on human foetuses.

In recent years, induced pluripotent stem cells have allowed scientists to grow human tissues, such as liver cells, in a laboratory, and we can therefore investigate the impact of smoking on them.

David Hay and his team from the University of Edinburgh’s centre for regenerative medicine investigated the impact of smoking on unborn babies’ livers.


The research

The team found that smoking during pregnancy damages the livers of unborn foetuses. Interestingly, they found a difference between males and females.

smoking2Image taken from babycenter.com

Previous research investigating the effects of smoking on the foetal liver has often used techniques such as animal models.

Although the findings from these studies have been helpful, species differences have meant that it is difficult to extrapolate the data to humans.

As a result, the true impact of maternal smoking on the infant’s liver was poorly understood.

This research team adopted a relatively new technique involving induced pluripotent stem cells, which has allowed them to monitor the impacts of smoking on human foetal liver cells.

They found that cigarettes harm the livers of unborn babies, and could cause lasting damage. Interestingly, smoking has a different effect on males and females. Female liver tissues showed more damage to cell metabolism, whilst male liver tissue demonstrated a higher level of scarring.


What are pluripotent stem cells?

Pluripotent stem cells are adult cells which have been “reprogrammed” to act like embryonic cells

smoking3image taken from learn.genetics.utah.edu

Pluripotent stem cells are cells which can differentiate into any cell type. They are very useful in developmental research, as studies can be undertaken on human cells. This removes the issue associated with extrapolation when animal models are used.

Typically, pluripotent stem cells are only found within the inner cell mass of a developing embryo. There are therefore ethical issues associated with their use, as an embryo would have to be killed for its pluripotent stem cells to be used.

In recent years, scientists have developed a technique which can turn a normal, adult body cell, into a pluripotent one. The resulting cell is referred to as being an induced pluripotent stem cell, as its pluripotency has been engineered.

To do this, genes responsible for maintaining pluripotency, such as sox2 and oct4, are “switched on” in the adult cell. After some culture time, the differentiated adult cells have been converted into pluripotent cells.

As a result, they have the potential to become any cell type. Changing the culture condition will stimulate different cell types to develop.

The research by David Hay and his team caused the pluripotent cells to develop into hepatoblasts. These are the foetal precursors of liver cells. As a result, they could investigate the impacts of smoking on foetal liver cells without extrapolation or ethical concerns.


Further information

smoking4Image taken from: sheknows.com

The debate surrounding smoking during pregnancy is an interesting discussion. On one hand, some believe that it is the mother’s body, and she should be allowed to decide what she puts into it. Others argue that the harm caused to the infant is so great that smoking during pregnancy should be illegal.

What about e-cigarettes?

Unfortunately, although e-cigarettes have less harmful components than regular cigarettes, they do contain nicotine. This can damage the foetuses’ developing brains and lungs.

Therefore, the best plan of action would seem to be to stop smoking. Of course, this is more easily said than done, as cigarettes are a highly addictive substance.

However, there are many online and in-person support groups available which may help you if you’re pregnant and trying to stop smoking.


For more information: http://www.nhs.uk/conditions/pregnancy-and-baby/pages/smoking-pregnant.aspx

The paper: https://link.springer.com/article/10.1007/s00204-017-1983-0