“Latest Stem Cells News”

In a landmark paper, researchers at Stanford University have described a new way to derive human induced pluripotent stem cells (iPSCs) without the use of contaminating mouse feeder cells. Using adipose cells as the starting cell population and mTeSR1, a defined medium that allows the expansion of human embryonic and induced pluripotent stem cells without the use of feeders, the researchers were able to fully reprogram the cells to the pluripotent state.

mTeSR1 is a fully defined medium and is the most widely used feeder-independent method for culturing human pluripotent stem cells, with citations in more than 25 publications.

read more on http://www.reuters.com/article/pressRelease/idUS155006+14-Sep-2009+BW20090914

Much to the dismay of patients and physicians, cancer stem cells — tiny powerhouses that generate and maintain tumor growth in many types of cancers — are relatively resistant to the ionizing radiation often used as therapy for these conditions. Part of the reason, say researchers at Stanford University School of Medicine, is the presence of a protective pathway meant to shield normal stem cells from DNA damage. When the researchers blocked this pathway, the cells became more susceptible to radiation.

“Our ultimate goal is to come up with a therapy that knocks out the cancer stem cells,” said Robert Cho, MD, a clinical instructor of pediatrics. “If you irradiate a tumor and kill a lot of it but leave the cancer stem cells behind, the tumor has the ability to grow back.” As a result, patients can relapse months or years after seemingly successful treatment.

Cho and radiation oncologist and post-doctoral fellow Maximilian Diehn, MD, PhD, are co-first authors of the research, which was published on Feb. 4 in Nature. They collaborated with scientists at Stanford and City of Hope National Medical Center to conduct the research. They studied breast epithelial stem cells from humans and mice to unravel why cancer stem cells are more resistant to radiation than other cancer cells.

“Since cancer stem cells appear to be responsible for driving and maintaining tumor growth in many tumors, it is critical to understand the mechanisms by which these cells resist commonly used therapies such as chemotherapy and radiotherapy,” said Diehn. “Ultimately, we hope to improve patient outcomes by developing therapeutic approaches that directly target cancer stem cells or that overcome their resistance mechanisms.”

The origin of cancer stem cells is still under debate. Some may arise from normal adult stem cells gone awry. Others may represent specialized cells from adult tissues that have acquired a stem-cell-like state through a series of mutations. What’s clear is that cancer stem cells can reconstitute an entire tumor cell population when transplanted into an immune-deficient animal, and destroying them is likely to be critical in order to stop the growth and spread of the disease.

Helen Blau

Scientists have now shown that skin cells can be coaxed to behave like muscle cells and muscle cells like skin cells.
The fickleness of the cells, and the relative ease with which they make the switch, provide a glimpse into the genetic reprogramming that must occur for a cell to become something it’s not.

“We’d all like to understand what happens inside the black box (cell),” said Helen Blau, professor and member of Stanford University’s Stem Cell Biology and Regenerative Medicine Institute and co-author of a new study on the subject.
Harnessing these genetic makeovers will allow scientists to better understand how to induce specialised adult cells to revert to a stem-cell-like state in a process called induced pluripotency (iPS).

But Blau’s experiments suggest an intriguing alternative to iPS: that of enticing specialised adult cells to switch identities without requiring a dip into the stem cell pool.
Blau, who heads the Baxter Lab at Stanford University and her lab members fused mouse muscle cells with human skin cells, to create hybrids called heterokaryons.

A new report brings bioengineered organs a step closer, as scientists from Stanford and New York University Langone Medical Center describe how they were able to use a “scaffolding” material extracted from the groin area of mice on which stem cells from blood, fat, and bone marrow grew. This advance clears two major hurdles to bioengineered replacement organs, namely a matrix on which stem cells can form a 3-dimensional organ and transplant rejection.

Alessandra Sacco

A study on mice directed by Alessandra Sacco of Stanford University has shown that once inserted into a diseased muscle, just one adult muscular stem cell can reproduce to form an entire ‘family’ of cells and restore lost muscular function. In a leg muscle with no muscular stem cells that has been irreversibly damaged, a single adult stem cell can take root and multiply, restoring muscular function.

The study was presented today in the Annual Meeting of the American Society of Cell Biology
(ASCB) in San Francisco. The muscular stem cells in this case are called ‘satellite cells’, which normally repair muscular tissue when it is damaged. In many degenerative muscular diseases however, this ‘natural repair’ is lacking and the muscular fibers degrade slowly. The validity of stem cell transplants into diseased muscle has been demonstrated on more than one occasion, but this is the first time that a single cell transplant has been performed.
The stem cell family born from the single cell was able to repair the muscle and restore its function, another step forward in stem cell research to cure degenerative muscular diseases.