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Human development: Donated embryo offers glimpse of events after implantation in womb

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We know little about human development just after implantation, but an embryo donated by one individual offers a rare look at the process



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17 November 2021

A day 16-19 human embryo viewed from the top (left image) and the side (right image)

Srinivas, Scialdone et al. (2021)

What happens in the first weeks after a human embryo implants in the uterus has been a black box. Now, biologists have had a chance to study this stage of development in detail for the first time.

The first week of development can be investigated by growing spare IVF embryos, while embryos older than 12 weeks are often donated for research by people after abortions. But samples of the stages in-between are exceedingly rare because few people realise they are pregnant and choose a termination at such an early stage.

Biologists have been particularly keen to study a process called gastrulation, which starts two weeks after a human egg is fertilised and a week after implantation. At this point, the embryo consists of a hollow ball made of a single layer of identical cells. It then folds to form a multilayered structure and the cells start to take on specialised roles.

“This is the stage where some of the key [developmental] decisions are taken,” says Shankar Srinivas at the University of Oxford. Understanding this fundamental process could lead to better ways of turning stem cells into useful cells for treating diseases and injuries, he says.

A donated embryo just 16 to 19 days old and in the process of gastrulating has now been studied by Srinivas’s team.

The donor must have suspected they were pregnant as soon as their period was late, and done a test and gone to a clinic the same day, says Srinivas. At the clinic, they would have been offered a medical abortion.

Most people choose to take the abortion-inducing drugs at home. In the UK, only those who decide to remain in a clinic are asked if they would like to donate material for research. The Human Developmental Biology Resource, a tissue bank backed by a number of academic institutions, the health research charity Wellcome and the UK Medical Research Council, then collects and prepares samples.

The researchers looked at which genes were active in every cell of the embryo. They found that gastrulation in humans is broadly similar to that in mice and monkeys, but with some key differences. For instance, some of the so-called growth factors that control the fate of cells are different.

The blood system was also already starting to form in the embryo, earlier than expected from mouse studies.

The researchers were able to identify and characterise the primordial germ cells, the cells that later give rise to sperm or eggs.

“It’s giving us this profile of what human primordial germ cells look like and how we might make them in the future,” says team member Richard Tyser, also at Oxford.

No nerve cells had yet formed in the embryo. “We could detect the earliest progenitors of neurons, but these cells give rise also to skin,” says Srinivas.

At present, guidelines and sometimes laws prohibit human embryos being grown in the lab for more than 14 days. Some researchers would like this to be extended, and the finding that no neurons are present in an embryo that was 16 to 19 days old will inform that debate, says Srinivas.

Journal reference: Nature, DOI: 10.1038/s41586-021-04158-y

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Solar storms may cause up to 5500 heart-related deaths in a given year

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In an approximate 11-year cycle, the sun blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field, which may disrupt our body clock and ultimately affect our heart



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17 June 2022

A solar storm

Jurik Peter/Shutterstock

Solar storms that disrupt Earth’s magnetic field may cause up to 5500 heart-related deaths in the US in a given year.

The sun goes through cycles of high and low activity that repeat approximately every 11 years. During periods of high activity, it blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field.

These so-called solar storms can cause glitches in our power grids and bring down Earth-orbiting satellites. A handful of studies have also hinted that they increase the risk of …

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UK Covid infection rate rising, with more than a million cases in England | Coronavirus

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Coronavirus infections are rising in the UK, figures have revealed, with experts noting the increase is probably down to the more transmissible BA.4 and BA.5 Omicron variants.

The figures from the Office for National Statistics (ONS), based on swabs collected from randomly selected households, reveal that in the week ending 11 June an estimated one in 50 people in the community in England are thought to have had Covid – around 1.13 million people.

The figure is even higher, at one in 45, in both Wales and Northern Ireland, while it was highest in Scotland where, in the week ending 10 June, one in 30 people are thought to have been infected.

While the figures remain below the peak levels of infection seen earlier this year, when around one in 13 people in England had Covid, the findings are a rise on the previous week where one in 70 people in England were thought to be infected. Furthermore, the data reveals increases in all regions of England, except the north-east, and across all age groups.

Experts say that a key factor in the increase is probably the rise of the Covid variants of concern BA.4 and BA.5.

“Infections have increased across all four UK nations, driven by rising numbers of people infected with the BA.4 and BA.5 Omicron variants,” said Kara Steel, senior statistician for the Covid-19 Infection Survey.

While Steel said it remained too early to say if this was the start of another wave, others have warned it may already have begun, with increased mixing and travelling among other factors fuelling a rise in cases.

Among concerns scientists have raised are that BA.4, BA.5 and another variant on the rise, BA.2.12.1, replicate more efficiently in human lung cells than BA.2.

Prof Azra Ghani, an epidemiologist at Imperial College London, said the latest figures were not surprising, and might rise further.

“This increase in infection prevalence is likely due to the growth of the BA.4 and BA.5 Omicron subvariants, which as we have seen elsewhere in Europe, appear to be able to escape immunity generated from previous Omicron subvariants,” she said.

“It is therefore possible that we will continue to see some growth in infection prevalence in the coming weeks and consequently an increase in hospitalisations, although these subvariants do not currently appear to result in any significantly changed severity profile. This does however serve as a reminder that the Covid-19 pandemic is not over.”

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NHS to offer women in England drug that cuts recurrence of breast cancer | Breast cancer

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Thousands of women in England with breast cancer are to benefit from a new pill on the NHS which reduces the risk of the disease coming back.

The National Institute for Health and Care Excellence (Nice) has given the green light to abemaciclib, which cuts the chance of breast cancer returning after a patient has had surgery to remove a tumour.

Trials showed that patients who had the drug with hormone therapy had a more than 30% improved chance of their cancer not coming back after surgery, compared with hormone therapy alone.

“It’s fantastic thousands of women with this type of primary breast cancer will now have an additional treatment option available on the NHS to help further reduce the risk of the disease coming back,” said Delyth Morgan, the chief executive of charity Breast Cancer Now.

“The fear of breast cancer returning or spreading to other parts of their body and becoming incurable can cause considerable anxiety for so many women and their loved ones.

“New effective treatments such as abemaciclib, which can offer more women the chance to further reduce the risk of the disease recurring, are therefore extremely welcome and this is an important step change in the drug options available for this group of patients.”

The twice-a-day pill is suitable for women with hormone receptor-positive, HER2-negative, node-positive early breast cancer at high risk of recurrence who have had surgery. About 4,000 women will benefit initially, Nice said.

Helen Knight, the interim director of medicines evaluation at Nice, said the draft recommendation came less than a month after abemaciclib received its licence.

“The fact that we have been able to produce draft recommendations so quickly is testament to the success of our ambition to support patient access to clinically and cost effective treatments as early as possible,” said Knight. “Until now there have been no targeted treatments for people with this type of breast cancer.

“Abemaciclib with hormone therapy represents a significant improvement in how it is treated because being able to have a targeted treatment earlier after surgery will increase the chance of curing the disease and reduce the likelihood of developing incurable advanced disease.”

Abemaciclib works by targeting and inhibiting proteins in cancer cells which allow the cancer to divide and grow. It normally costs £2,950 for a packet of 56 150mg-tablets, but the manufacturer, Eli Lilly, has agreed an undisclosed discounted price for NHS England.

“Thanks in part to this latest deal struck by NHS England, NHS patients will be able to access another new targeted drug for a common and aggressive form of breast cancer,” said Prof Peter Johnson, the cancer director of NHS England.

“Abemaciclib, when used alongside a hormone therapy, offers a new, doubly targeted, treatment option, helping to increase the chances of beating the cancer for good, as well as meeting the NHS’s commitment to delivering improved cancer care under our long-term plan.”

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