New source for regenerative stem cells? Your own fat
Researchers at UCLA say they’ve found an abundant, cheap and easy-to-obtain source of stem cells that could prove to be ideal for regenerating all basic tissue types of the human body. The source is adipose tissue, as in your own fat.
Discovered in human fat in 2001, stem cells were called adipose stem cells. However, the cells found by UCLA researchers are different, according to a report published July 7, 2013 in the journal, PLOS One.
Lead researcher Gregorio Chazenbalk says that, unlike adipose stem cells, these different cells were first discovered in bone marrow. These cells, dubbed MUSE, appear to be more capable of differentiating into one of many cell types – more like embryonic stem cells, rather than so-called “adult” stem cells – meaning they can develop into any kind of tissue in the body.
Put simply, these MUSE cells have more of an ability to endure stress, which is is how Chazenbalk found them by accident.
According to Chazenbalk, he was working in isolation on cells late at night when a critical machine stopped working. Since it was so late, he couldn’t borrow a machine from another lab, so his cells didn’t received any nutrients or hardly any oxygen; thus, they presumably died.
But that didn’t deter Chazenbalk.
“Instead of throwing them all away, I decided to see if some survived,” he said.
And some cells did survive, eventually forming into what Chazenbalk described as clusters of cells, a characteristic of embryonic stem cells. But these clusters turned out to be MUSE cells.
The next thing Chazenbalk did was contact plastic surgeons to obtain several liters of fat that had been suctioned out of women during liposuction. He then created a formula to attract MUSE cells out of the fat.
To accomplish this task, Chazenbalk and his research team sorted through the collection of adipose cells by exposing them to stressful chemicals, low oxygen and low nutrition. The survivors were MUSE cells.
MUSE cells display many of the same genetic hallmarks of embryonic stem cells, but they also appear capable of differentiating into one of many cell types and affecting more than one organ.
If Chazenbalk and his research team have indeed found adult stem cells that can truly differentiate into cells that can repair damage to the human body, it will be a major breakthrough.
Nevertheless, some stem cell scientists remain skeptical. They claim that the one thing MUSE cells will not do is form a tumor called a teratoma, which is like an inside-out embryo with different types of tissue, including hair and teeth. And, ever since the dawn of embryonic stem cells, injecting cells into an animal and looking for a teratoma has long been the “gold standard” for testing a cell’s ability to develop into other potential cell types.
That's one reason why Martin Pera, program leader of Stem Cells Australia and a professor at the University of Melbourne, says that the findings of “the current study are interesting, but preliminary”. Although Pera praises the study itself, he cautioned that such hopes have been raised before only to be dashed upon further investigation.
“Evidence that MUSE cells can actually turn into a wide range of mature functional body cells is somewhat limited,” he said.
Jeffrey Gimble, an adipose stem cell expert and chief scientific officer of a company that researches stem cells from fat, said that “everything Chazenbalk says is consistent with what others have published.”
Gimble added that the quality of the study was “strong”, but he expects “pushback” from some stem cell experts because they even get contentious over what to call various types of cells.
Despite criticism from skeptics, which Chazenbalk expected to get, he still believes that MUSE cells from fat could be a boon for regenerative medicine. He explained that existing methods of using cells to repair tissue damage often fail because many of the transplanted cells are unable to survive in the stressful conditions of an injury site.
However, Chazenbalk points out, MUSE cells sit quietly in fat (or bone marrow), acting kind of like a reserve fire department. Once the body experiences damage, chemical signals are sent to the MUSE cells, signaling them to come to the rescue. Because MUSE cells thrive under the stress of an injury site (e.g. a burn, stroke, heart attack, etc), they are capable of differentiating into the needed cell types to repair the damage (unlike many transplanted cells).
Moreover, hundreds of thousands of liposuction procedures are performed each year, so there’s a virtually unlimited supply of the raw fat that MUSE cells can be sifted out from in about six to 12 hours, said Chazenbalk.
“We can directly use these cells for treatment,” he said. “Somebody could use their own cells as an autologous transplant,” raising the possibility that one could slim down and undergo repair at the same time.
According to Chazenbalk and his research team, in-vitro testing of the cells suggests that they may be truly pluripotent, contrary to what the skeptics say. If he and his team are right, that means these cells could truly be differentiated into every one of the approximate 200 types of human cells in the body, similar to what can be done with embryonic stem cells and induced pluripotent stem cells.
SOURCE: "Awakened by Cellular Stress: Isolation and Characterization of a Novel Population of Pluripotent Stem Cells Derived from Human Adipose Tissue" (published June 7, 2013) PLoS ONE 8(6): e64752. doi:10.1371/journal.pone.0064752