Genetic Profile Distinguishes Types of Stem Cells

Researchers at the The Scripps Research Institute found a new way of classifying the many cell types that fall under the category of “stem cells.” The term stem cell refers to tissue specific stem cells found in mature tissues such as blood, brain, or muscle, which are restricted to forming only cells found in those tissues, as well as to embryonic stem cells that are broadly able to form all cells of the body. The term is also used to refer to the so-called induced pluripotent stem (iPS) cells that scientists can now create out of adult skin cell and that mimic embryonic stem cells in their ability to form a variety of cell types. In this work, the researchers discovered a set of genes that are always active in the pluripotent cells – whether they were iPS cells or embryonic stem cells. As more stem cell populations become available, the gene profile discovered in this study will help researchers distinguish those cells that are truly pluripotent from those that are more restricted in the cell types they are able to form.

Nature: September 18, 2008
CIRM funding: Louise Laurent (T1-00003)

Related Information: Scripps news story, The Scripps Research Institute

Genetic Factor Influences Heart Muscle Formation from Embryonic Stem Cells

Researchers at the Gladstone Institute for Cardiovascular Disease discovered how two specific tiny genetic factors called microRNAs influence the differentiation of embryonic stem cells into heart muscle. They found that the factors not only drive the versatile cells to become heart, but also actively prevent them from becoming other tissue such as bone adding to their potential to make therapy more specific and targeted for patients.

Cell Stem Cell: March 6, 2008
CIRM funding: Kathey Ivey (T2-00003), E. Hsiao (T2-00003), Deepak Srivastava (RC1-00142)

Related Information: Press release, Gladstone Institute of  Cardiovascular Disease,Srivastava bio

Human Embryonic Stem Cells Trigger Immune Reaction in Mice

Researchers at the Stanford University School of Medicine have found that human embryonic stem cells trigger an immune response much like organ rejection when transplanted into mice. In the past, researchers had thought that transplanted embryonic stem cells might not be rejected the way transplanted organs are. Testing this theory, the team found that after transplanting human embryonic stem cells into normal mice, those cells disappeared within seven to ten days. In mice without an immune system the cells survived and even multiplied. Drugs used to prevent organ rejection also successfully prevented normal mice from rejecting the transplanted stem cells. These results suggest that any therapy involving transplanted embryonic stem cells will also require a way of preventing people from rejecting those therapeutic cells.

Proceedings of the National Academy of Sciences: September 2, 2008
CIRM funding: Joseph Wu (RS1-00322)

Related Information: Press Release, Stanford Stem Cell Biology and Regenerative Medicine Institute, Wu bio