Biologists from Israel’s Weizmann Institute of Science have grown a mouse embryo — complete with beating heart cells, a head, and greenshoots of limbs — in an artificial womb for 12 days, longer than ever before. That’s about half the animal’s natural gestation period. The human equivalent of the period would be the first trimester.
How: The embryo was not grown in vitro starting from a fertilised egg. Instead, the scientists collected 5-day-old embryos from pregnant mice and moved them into glass vials filled with a special nutrient liquid. The vials were slowly spun and provided with a pressurised oxygen mixture. The mouse embryos grew till Dat 12 and only died after they became too large for the oxygen to diffuse through them, since they lack the natural blood supply a placenta could provide. The findings were published in the journal Nature (paywall).
The significance: Much of what is known about mammalian embryonic development today comes either from observing the process in non-mammals like frogs or fish that lay transparent eggs, or by obtaining static images from dissected mouse embryos (at different stages of development) and adding them together, explains Prof. Jacob Hanna of the Weizmann Institute. Growing an embryo in the lab gives scientists a whole new level of insight.
And marks a step towards… the ethical minefield of developing human embryos in a glass jar. In fact, in the same issue of Nature, two other research groups reported a leap forward in creating “artificial” human embryos, the MIT Technology Review notes.
Guardrails: Scientists currently adhere to a protocol of not developing human embryos beyond 14 days of sterilisation. Some countries have coded that as a law. But there are calls for allowing human embryos to grow longer. Hanna says doing so also would give access to lab-grown embryo tissues required for scientific research — for example, in the development of vaccines — instead of obtaining them from abortions.
(Source: Weizmann Institute of Science)