Thursday, September 15, 2011

IPS Stem Cells Are Looking More Promising for Regenerative Medicine

George Church is a professor of genetics at Harvard Medical School. He is becoming more and more deeply involved in the field of regenerative medicine, using induced pluripotent stem cells (IPS). Church was interviewed recently on how he sees the field of IPS regenerative medicine progressing.
A pioneer in developing DNA sequencing technologies, and in researching everything from epigenetics and microbiomics to synthetic biology, Church has co-founded or advises over 20 companies. He also has launched the Personalized Genome Project with a goal of sequencing the complete genomes of 100,000 volunteers.

When I asked Church what he was most excited about right now, he answered without hesitation: "I'm thinking a lot about using regeneration as the key to treatments and keeping people healthy."

TR: You mean regeneration using stem cells?

Church: Yes, induced pluripotent stem (IPS) cells (see, "Growing Heart Cells Just for You"). This is where I'm putting almost all of my chips these days, because it combines many of my interests--genomics, sequencing, epigenetics, synthetic biology, stem cells. I don't think people have fully appreciated how quickly adult stem cells and sequencing and synthetic biology have progressed. They have progressed by orders of magnitude since we got IPS. Before that, they basically weren't working.

Is this because IPS cells are relatively easy to create and to engineer?

You can use them to reprogram genomes--not sequence them, but to reprogram them genetically and epigenetically. In other words you make the minimum changes it takes to get them where you want them to be genetically and epigenetically and then you program the cells into tissues.

What do you mean?

Let's use stem cells in bone marrow as an example. They are easy to use and to get to work when you implant them in bone marrow. You might one day have three choices. You can have bone marrow from someone else that is matched to you, or that is from you, or bone marrow that is matched to you and comes to you, but is better than you. This better bone marrow might be [engineered to be] resistant to one virus, or to all viruses. It could have a bunch of alleles that you picked out of super centenarians, alleles that you have reason to believe are at least harmless and possibly helpful. So now you have choice, a patient who can take a good bone marrow that he might reject and you'll be on immunosuppressants your whole life. Or you might use your own, or your own that might fix the cancer, or your own enhanced bone marrow. And you will be able to do that for almost every stem cell population. Some of them are a little bit harder to replace, though.

Does IPS really work to accomplish this regeneration?

We have good evidence that you can create an entire mouse from IPS cells.

Has this been done?

This has been done. They have used IPS cells to grow a mouse, and they made IPS cells from that mouse. They're totipotent [able to make an entire organism], not merely pluripotent. We haven't done this for humans for obvious ethical reasons, but we will do it. As far as I know the mice have done fine.

But haven't there been some problems with mutations occurring with IPS-generated tissue?

We have a recent paper in Nature that shows that when you make human induced pluripotent stem cells you actually do get mutations in coding regions at a slightly elevated level. But I think this is temporary. We're going to use this information as an assay to make the process work better, to correct problems. You will be able to use this to improve the quality of gene therapy because that's been the problem with gene therapy the last ten years.

How far are we from testing that in humans?

Almost everything I've described has been done in rodents, so we're talking about years, not decades. It's shorter than the Human Genome Project [which took 13 years], not less expensive, but definitely shorter. _TechnologyReview
Scientists at the University of Toronto have recently made a breakthrough in the control of IPS cells' pluripotency:
Scientists have found a control switch that regulates stem cell “pluripotency,” the capacity of stem cells to develop into any type of cell in the human body. The discovery reveals that pluripotency is regulated by a single event in a process called alternative splicing.

Alternative splicing allows one gene to generate many different genetic messages and protein products. The researchers found that in genetic messages of a gene called FOXP1, the switch was active in embryonic stem cells but silent in “adult” cells—those that had become the specialized cells that comprise organs and perform functions.

“It opens the field to the fact that alternative splicing plays a really important role in stem cell pluripotency,” said Prof. Benjamin Blencowe, principal investigator on the study and a Professor in the University of Toronto’s Departments of Molecular Genetics and Banting and Best Department of Medical Research. “We’re beginning to see an entirely new landscape of regulation, which will be crucial to our understanding of how to produce more effective pluripotent stem cells for therapeutic and research applications.”

The findings were published in the current online edition of the scientific journal Cell. _Source
These are some fascinating developments, which will eventually lead to advanced therapies for diseases which are currently untreatable, such as cancers and end stage degenerative diseases of the heart, lungs, liver, kidneys, and brain.

The ability to grow replacement organs from stem cells is already being proven in animals. The ability to regenerate a badly degenerated organ in situ, using stem cells, is also being proven. According to George Church, stem cells are also the best method for making genetic improvements to organs and organisms.

BioHeart's clinical stem cell trials in Mexico

ThermoGenesis an early commercial entrant into the human stem cell regenerative medicine industry

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