Scientists grow 'complete' model of human embryo without egg or sperm

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Scientists have grown in the lab what they describe as a "complete" model of a two-week-old human embryo without the use of eggs or sperm — a path-breaking research that experts hope will help them understand the earliest moments of human life and aid in pharmaceutical testing and fertility treatment.

The research team from Israel's Weizmann Institute says their "embryo model", which was grown using stem cells, looked like a "textbook example of a real 14-day-old embryo", according to the BBC. It reported that the entity even released hormones that turned a pregnancy test positive in the lab.

"This is the first embryo model that has structural compartment organisation and morphological similarity to a human embryo at day 14," Prof Jacob Hanna, who led the research, told the Guardian.

The minuscule structures of the entity were not wholly identical to human embryos, but scientists hope that the research would prove to be an ethical way to understand "earliest stages of human development and so far unknown causes of miscarriage", the Guardian report added.

In the first weeks, an embryo undergoes rapid changes; this is when many miscarriages happen and congenital disabilities take root. "It's a black box, and that's not a cliche - our knowledge is very limited," Hanna told the BBC.

There are other wide-ranging implications of the Weizmann Institute research, which stands out in a field that has drawn massive interest among the medical fraternity and led to a plethora of papers in recent times.

Hanna told the Guardian that their research could be used to create model embryos from skin cells of ill patients — and then these entities could be used to "develop organs that can be used as a source of cells to transplant into the patients".

The scientist stressed that before growing such a model embryo, its genetics would be tweaked to make sure "it did not develop a brain or nervous system". Another potential application "is using model embryos to assess the probable impact of medicines on real human embryos", the Guardian report added.

In future, the research could also help improve in vitro fertilisation (IVF) success rates "by helping to understand why some embryos fail or using the models to test whether medicines are safe during pregnancy", according to the BBC report cited above.

In the peer-reviewed research published in Nature Journal, naive stem cells were reprogrammed so that they could become any type of tissue in the body, the BBC reported. No sperm or eggs were used. Next, chemicals were used to turn the stem cells into the type of cells found in an early-stage human embryo.

"I give great credit to the cells - you have to bring the right mix and have the right environment and it just takes off," Hanna told the BBC. "That's an amazing phenomenon."