Monday, November 29, 2010

World Stem Cell Summit and a Primer on Stem Cells in Michigan

The World Stem Cell Summit took place at the Marriott Renaissance Center in Detroit, October 4-6. Co-hosted by the Genetics Policy Institute (GPI), the state of Michigan and the University Research Corridor, consisting of the Univerisity of Michigan, Michigan State and Wayne State University—it is the largest event the stem cell/regenerative medicine community hosts annually. So why pick Detroit as the host site for such a high profile event.

Anybody remember Proposal Two on the ballot during the last presidential election? The law, passed in 2008, protects embryonic stem cell (eSC) research in Michigan, with provisions that direct the research funds towards therapeutic ends in the public sector. While allowing scientists to use embryos, developed in fertility clinics, that would otherwise be discarded, Proposal 2 states that only donated embryo’s can only be used, and they must be utilized before day 14 for making embryonic stem cell (eSC) lines. Essentially, you can only use embryos that were going to be disposed of anyway. At day 14, embryos look like this…

Scientists actually want to take cells about 11 days earlier in the process, when they look more like this...

At this stage most embryos haven’t implanted and studies show 30-60% never will. Implantation in the uterus is the first true stage of pregnancy where a woman’s body physically changes and they can, potentially, sense being pregnant. Day 5 embryos are a ball of nearly identical cells that haven’t begun to form organs, and generally, haven’t implanted into the uteral lining. The goal of producing eSCs is to obtain the cells at the earliest points in development, before they specialize (differentiate is the technical term) into specific tissue or blood cells you see in later stages of development. The end goal is to direct cell specialization, so they can replace damaged tissues in those who need it.

One major issue that opponents of embryonic stem cell work bring up is the lack of immediate, effable treatments. Most say that adult stem cell and induced stem cell therapies are closer to becoming legitimate treatment strategies. This is a valid point. Adult stem cells and induced stem cells can be collected/generated from an individuals own stock of cells and therefore bypass issues of graft rejection that you would see with eSCs. However, finding and isolating adult stem cells can be extremely difficult in many tissues, particularly the brain and spinal chord. In addition, induced pluripotent stem cells are stem cell like, expressing many of the same genes, however, it is unclear how similar they are to naturally occurring stem cells, and if they can function the same way.

A technique called Somatic Cell Nuclear Transfer (SCNT) bypasses most of the arguments. In SCNT the nucleus of an unfertilized egg (one that has not fused with a sperm) is replaced with one from an adult containing all of their genetic information. Remember ‘Dolly’ the cloned sheep? This is how she was made.

While SCNT is the primary technique used, it’s not an attempt to make human Dollys. We are not trying to clone entire human beings we are trying to make fresh copies of certain subsets of cells. The goal is to be able to take patient DNA, implant it into an unfertilized egg and make a small mass of undifferentiated cells that they can direct to replace tissues that are irreparably damaged. This small mass of undifferentiated cells would be similar to the eSCs discussed above except they would have the patients own DNA.

This technique has the greatest therapeutic potential of any out there, and it avoids using embryo’s in the process. The problem? SCNT has never produced a stem cell line. The SCNT works and the egg begins to divide normally, but at some point before stem cell lines can be established, cell division stops, and the cell lines die.

Proposal 2 allows scientists to take the next step in studying eSC use for therapeutic ends in this state. Michigan is giving its Universities and Biotech Businesses a leg up on many other states with the option to donate fertilized embryos, that would be discarded otherwise, to medical research. A stem cell research group at the University of Michigan cloned the state’s first eSC line a couple days before the summit. This could open up opportunities for major collaborations in regenerative medicine in this state and may result in creating some new jobs. Hosting the World Stem Cell Summit certainly establishes that the regenerative medicine community see some potential in doing their work in Michigan. Let’s hope it leads to something, this state could use it.

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