Scientists Make Human Stem Cells Through Cloning

DNA removal from cell The first step during SCNT is enucleation or removal of nuclear genetic material (chromosomal) from a human egg.

Researchers announced Wednesday, May 15, in the journal Cell that they’ve been able to make stable colonies of embryonic stem cells by injecting the DNA from ‘adult’ human cells into a human egg cell emptied out of its genetic material.

“Our finding offers new ways of generating stem cells for patients with dysfunctional or damaged tissues and organs,” study researcher Shoukhrat Mitalipov of Oregon Health & Science University, said in a press release. “Such stem cells can regenerate and replace those damaged cells and tissues and alleviate diseases that affect millions of people.”

This technique they used to make these stem cells is called somatic cell nuclear transfer, and is the same technique used to clone animals, like Dolly the sheep.

To put it in very simplified terms: the researchers first harvest a human egg from a woman’s ovaries and completely remove her genetic material from the egg. Then, they take a human skin cell and insert it into the egg using an inactivated virus which fuses the two cells. The embryo that grows from this would be a genetic copy of the person that donated the cell. 

That doesn’t sound complicated, but because of the special reactions that take place when sperm meets egg in a naturally conceived embryo, there are changes that take place to the DNA that are hard to recreate in the lab. The researchers had to give the egg a “jump start” of electricity to fool it into thinking it was fertilised.

It’s also difficult because when a cell is an “adult” it’s already committed to being a certain type of cell — which is why muscle cells look and act in different ways than brain cells. It’s very difficult to reverse the changes to the genome that happen during this process.

This is a feat that’s been in the works for 16 years, since Dolly was cloned.

somatic cell nuclear transfer technique

In 2011, a Nature paper detailed a similar finding, but the cloned cells had an extra set of chromosomes. When they tried to make the embryos with the normal set, they were unable to grow into the balstocyst stage — an early-stage embryo that contains 150 cells. 

In the new study the researchers showed they were able to take cells from these cloned embryos and grow them in a dish like any other embryonic stem cells. To do this, they had to add a bit of caffeine to the mix.

They also showed that they could make multiple different types of cells from the embryonic stem cells — a trait called pleuripotentcy that is the marker of stem cells.

If tests of these cells show that they act just like regular embryonic stem cells, researchers would be able to make embryonic stem cell lines from any given person — using their own genome harvested from one of their cells.

But researchers warn that this doesn’t mean we can go about making little versions of ourselves just yet.

“Reproductive cloning hasn’t been advanced by this new paper,” Rudolf Jaenisch of the Massachusetts Institute of Technology told Reuters. “If you implanted these embryos, which would be illegal, I think you would get the same results as in mice: Most of them die at birth, and the others encounter big troubles as they age.”

They would also be able to avoid using fertilised embryos (which some people consider morally wrong) to create these embryonic stem cell lines. Here’s what the cells look like under the microscope:

cloned embryonic stem cell colonyThis is a colony of human ESCs (upper portion) extracted from a blastocyst generated by SCNT

They were then able to grow those cells in certain chemicals that pointed them in the direction of maturing into heart cells. You can see those cells beating in the video below:

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