Category: Nanodot

from the regenerative-medicine dept.
Numerous reports appeared in late-January 2002 in response to a press release (23 January) that reports on a claim by Dr. Catherine M. Verfaillie and colleagues at the University of Minnesota Stem Cell Institute (SCI) that they have isolated a type of stem cell found in adults that can turn into every single tissue in the body. Previously, only stem cells from early embryos were thought to be able to do this. If the finding is confirmed, it will mean cells from your own body could one day be turned into all sorts of perfectly matched replacement tissues and even organs. The finding generated a high level of interest because, if confirmed, there would be no need to resort to therapeutic cloning — cloning human embryos to get matching stem cells from the resulting embryos. Nor would you have to genetically engineer embryonic stem cells (ESCs) to create a "one cell fits all" line that doesn't trigger immune rejection. The discovery of such versatile adult stem cells will also fan the debate about whether embryonic stem cell research is justified.

Additional coverage can be found in articles from the New York Times ("Scientists Herald a Versatile Adult Cell", by N. Wade and S.G. Stolberg, 25 January 2002) and United Press International ("Adult stem cell findings lauded", 24 January 2002).

In related news that demonstrates the importance of this line of research, Dr. Verfaillie announced in another press release (30 January 2002) that her team has demonstrated, for the first time, the ability of adult bone marrow stem cells to expand in vitro as endothelial cells (which line blood- and lymphatic vessels) and then engraft in vivo and contribute to new growth of blood vessels (neoangiogenesis). The report appeared in the 1 February 2002 issue of the Journal of Clinical Investigation. Verfaillie and her colleagues announced late last year that these cells, called multipotent adult progenitor cells (MAPCs), demonstrate the potential to differentiate beyond mesenchymal cells, into cells of the visceral mesodermal origin, such as endothelium, and may be capable of differentiating into nonmesodermal cell types, such as neurons, astrocytes, oligodendrocytes, and liver.

According to a report from the UK-based New Scientist (" ëFunctionalí kidneys grown from stem cells", by Claire Ainsworth, 29 January 2002), researchers at Advanced Cell Technology in the U.S. claim to have grown functional bovine kidneys using stem cells taken from cloned cow embryos. The report says the ACT researchers, working in collaboration with a group at Harvard University, coaxed the stem cells into becoming kidney cells, and then "grew" them on a kidney-shaped scaffold. The two-inch-long mini-kidneys were then transplanted back into genetically identical cows, where they started making urine. If confirmed, the work raises the prospect of using stem cells taken from human patients with kidney failure to create new organs for transplant. ACT did not reveal details, and the work has not yet been published in a peer-reviewed journal. As the NS article notes, no details are available as to exactly what these miniature kidneys are, and whether they are in fact complete, functional organs. The kidney is a very complex organ, with an intricate supply of blood vessels that are key to its ability to filter blood.

Additional coverage appeared in the New York Times ("Company Says It Used Cloning to Create New Kidneys for Cow", by K. Chang, 31 January 2002).

According to a press release (25 January 2002), a new study by researchers at National Jewish Medical and Research Center and the University of Colorado Health Sciences Center shows that a synthetic antioxidant can delay and prevent the onset of autoimmune diabetes in mice. The antioxidant protected insulin-producing beta cells from lethal oxygen radicals generated in diabetes. The antioxidant also blocked the ability of the immune system to recognize beta cells, the target of the autoimmune attack in diabetes. The findings suggest that antioxidants may be useful against diabetes as well as other autoimmune diseases and organ-transplant rejections. The researchers used a synthetic catalytic antioxidant developed several years earlier by one of the researchers, and now licensed by Incara Pharmaceuticals Corporation. The antioxidant, dubbed AEOL 10113, mimics the naturally occurring antioxidant superoxide dismutase, but is effective against a wider range of antioxidants and lasts longer in the body. The findings, published by in the February issue of Diabetes, suggest that antioxidants may be useful against diabetes as well as other autoimmune disorders. Additional article can be found in this article (25 January 2002). from United Press International.

This research is following a line similar to that being explored by MetaPhore Pharmaceuticals, which is also testing a family of synthetic analogs of superoxide dismutase (see Nanodot posts from 12 July and 14 December 2001).

A news items from Science@NASA ("Voyage of the Nano-Surgeons", by Patrick L. Barry, 15 January 2002), a news service of the U.S. National Aeronautics and Space Administration (NASA), describes work at the NASA Ames Research Center to develop "nanoparticles" and "nanocapsules" that will hunt down diseased cells and penetrate their membranes to deliver precise doses of medicines. The hope is that the tiny capsules may someday be injected into people's bloodstreams to treat conditions ranging from cancer to radiation damage.

Read more for details of the project and web links to other resources.

An article in EE Times ("Scientists activate neurons with quantum dots", by R. Colin Johnson, 6 December 2001) describes research by scientists led by Christine Schmidt, an assistant professor of biomedical engineering at the University of Texas-Austin to use quantum dot devices to selective electrical contacts to neurons. According to the article, by selectively coding peptides that coated quantum dots, University of Texas scientists precisely controlled the spacing of hundreds of quantum dots on the surface of the living neurons. The cadmium sulfide contacts act as photodetectors, allowing researchers to communicate with the cells using precise wavelengths of light.

The research has some . . . interesting implications:

In this new biological application, attaching quantum dots directly to cells eliminates the need for external electrodes. The procedure is entirely non-invasive, similar to the use of fluorescent dyes to mark cells. And since molecular recognition is used, it is a "smart" technology that can pick precisely which capability will be controlled on each neuron to which a quantum dot is attached. Taken to the logical extreme, biologists could remotely control any neural function by activating select neurons.

"Presumably, in the future we will be able to turn on an ion channel or turn off something else," said Schmidt. "We could have highly regulated activity in the neuron. . . . One idea is to put a quantum dot right next to a protein channel ó one that opens and closes ó allowing ions to go in and out, and basically control the ion exchange, which in turn controls action potentials [neuron 'firing']. These are the electrical signals with which the neuron interacts with the brain."