Stem Cells May Be Evolutionary Remnants

Stem Cells May Be Evolutionary Remnants

In a paper to be published in November’s Molecular And Cell Biology, researchers at the Max Planck Society in Germany have demonstrated that some adult stem cells could be the “remnants of former embryonal differentiation processes, or, in other words, ‘footprints’ of evolution.” (The press release also includes some cool images, take a look!)

In the research, the scientists used two mesenchymal stem cells lines from the bone marrow in mice, but did not stimulate growth artificially. They found that the two lines expressed different markers, which suggests that the stem cells are heterogenous rather than identical in nature. The scientists then applied different substances to the cells and caused the cells to express characteristics of heart muscles cells and of skeleton muscle cells. However, in both cases the differentiation process did not conclude. The scientists were able to observe fusion between the stem cells and other muscle skeleton cells.

The press release concludes,

The Max Planck researchers have two possible explanations for their results. On one hand, the stem cells could be missing some factor which is absolutely necessary for the complete differentiation into specialised cells and tissue. On the other hand, it could be the case that at least some of the known adult stem cell types are "only" the rudiments of earlier embryonal differentiation processes, or even dispersed leftovers from previous evolutionary stages. Indeed, these cells are still showing plasticity which is a characteristic of stem cells, but no direct physiological function can be deduced from it.

So what does this mean? Well, I am not entirely sure, but I think that the study is suggesting that DNA still carries instructions for processes which are no longer adaptive to the organism and are therefore unnecessary—junk, so to speak. The result is stem cells which no longer have the capacity to differentiate on their own and are floating around aimlessly.

Interestingly, it was by stimulating the wnt protein path that the researchers were able to get the cells to begin to differentiate into heart muscles cells. The wnt protein group and signaling pathway is increasingly emerging as significant in both stem cell and cancer research. A useful link for more on wnt, including links to abstracts about wnt in stem cells, is The WNT Homepage.

Stem Cell Research on HIV/AIDS

Stem Cell Research on HIV/AIDS

At yesterday’s meeting of the California Independent Citizen’s Oversight Committee, the group directing the stem cell research program, UCLA virologist Jerome Zack presented research on using bone marrow stem cells to fight HIV infection. The story is reported in the San Jose Mercury News (free registration required) and in the Bay Area Reporter. The research involves inserting a new gene into the stem cells; the gene replaces the gene in the cells which is vulnerable to HIV. The virus is then cut in half by a DNA fragment known as a ribozyme. A clinical trial of 10 patients to test safety recently ended, and the patients had no problems. Additionally, the HIV-resistant cells were still present, in some patients as many as five years after the initial procedure.

A new trial to test this method as a therapy is currently enrolling people. The participants will have their blood stem cell growth stimulated, then have the blood drawn and the stem cells genetically modified. They are then reinserted into the blood stream. Patients will at several points during the treatment stop taking anti-viral medications to allow the HIV virus to kill unprotected blood cells, which will encourage the protected blood cells to replicate rapidly. The trial will take about 18 months.

This is not seen as a cure for AIDS, but as another form of therapy that would, if effective, allow patients to spend periods of time without anti-viral medications and their associated drawbacks.

A PDF outlining the study method, contact information, and so on is available online at the UCLA Institute For Clinical AIDS Research and Education. Deadline is December 9, 2005.