Editor's Note: Science Scan is a roundup of recently published biotechnology-relevant research.
Stem cells have a huge potential in medical therapy because it's in their nature to differentiate into many different cell types. They potentially provide replacements for cells that have been permanently lost by a patient (or a mouse).
An example would be a neurodegenerative malady such as Parkinson's disease, in which neurons that secrete dopamine are lost from the brain. Stem cells may ameliorate that condition by regenerating the missing neurons. Another example is Type I diabetes mellitus in which beta cells are lost from the pancreas. They might be treated by generating new beta cells.
As a rule, gestational cells develop along a pathway of increasing specialization. In humans and other mammals, those developmental events are controlled by mechanisms and signaling pathways that researchers are only beginning to comprehend. One of science's great challenges is to find ways of selectively differentiating embryonic stem cells (ESCs) into specific cell types of interest. "It's hard to control which specific lineage the stem cells differentiate into," observes Xu Wu, a doctoral candidate in the Kellogg School of Science and Technology at the Scripps Research Institute in La Jolla, Calif.
He and his colleagues have identified a small synthetic molecule that can control the fate of embryonic stem cells. "This compound," Wu volunteered, "is called Cardiogenol C. It causes mouse embryonic stem cells to selectively differentiate into cardiomyocytes,' or heart muscle cells. This is an important step on the road to developing new therapies for repairing damaged heart tissue. Likewise," he went on, "a damaged heart, which is composed mainly of cardiac muscle cells that the body may be unable to replace, could potentially be repaired with new muscle cells derived from stem cells."
Wu is first author of the study to be published in an upcoming issue of the Journal of the American Chemical Society. Its senior author is chemical biologist Peter Schultz, a professor at Scripps. The paper is titled "Small molecules that induce cardiomyogenesis in embryonic stem cells." It was released online Jan. 3, 2004, by the journal.
The Scripps scientists reasoned that if stem cells were exposed to certain synthetic chemicals, they might selectively differentiate into particular types of cells in the body. To test that hypothesis, they screened some 100,000 small molecules from a combinatorial library that they synthesized. From the assortment they designed a method to identify molecules able to differentiate mouse embryonic stem cells into heart muscle cells. Cardiogenol C proved to be effective at directing more than half of their tests to thus differentiate. Existing methods reportedly result in merely a 5 percent success rate of their tested stem cells - namely ESCs - turning into cardiomyocytes.
The Genomics Institute of Novartis Research Foundation collaborated in the embryonic stem cell research project.
Metabolic Syndrome' - Obesity, Low HDL-Cholesterol, Impaired Glucose Tolerance - Hits Hispanic Youth
Large numbers of Hispanic youth already have complications of obesity. They include impaired glucose tolerance, which can lead to diabetes and metabolic syndrome. The findings are published in the January 2004 issue of The Journal of Clinical Endocrinlogy and Metabolism. They caution that Hispanic youth may have underlying risk factors that make them more susceptible to diabetes, cardiovascular risks and the so-called metabolic syndrome. That is a collection of health risks that, besides obesity, include dyslipidemia (high blood triglycerides and low HDL-cholesterol and high blood pressure). Those symptoms include the chance of developing heart disease, stroke and diabetes. They affect more than 20 percent of adults in the U.S. Hispanics experience the highest rates of metabolic syndrome, with rates near 32 percent.
During the past 10 years, the obesity rate, which increases risk of developing metabolic syndrome, has doubled among Hispanic youth. The rates of Type II diabetes and impaired glucose tolerance also have increased in that group. Researchers at the University of California at Los Angeles (UCLA) conducted two separate surveys on data collected in overweight Hispanic children to determine some of the risk factors they incur.
Obesity and the complications associated with the problem are growing among minority children in the U.S., explained Martha Cruz, the primary author on the study and an assistant professor at UCLA. "We hope that our research will help the medical community better understand how to determine which children are at risk for developing diabetes, metabolic syndrome and cardiovascular disease," she observed.
Studies From Holland, Canada Report Widespread Environmental Presence of Enterobacter sakazaki
A bacterium called Enterobacter sakazakii might be dangerous to premature babies and young infants. It could be more widespread in the environment than previously thought. An issue of The Lancet, dated Jan. 4, 2004, is titled "Occurrence of Enterobacter sakazakii in food production environments and households." It is accompanied by a commentary headed, "Enterobacter sakazakii - new food for thought?" In previously described outbreaks, infant formulas contaminated during factory production or bottle preparation were recognized as a harmful source for bacterial colonization.
Chantal Kandhai, from Wageningen University in the Netherlands, and her co-authors used a refined isolation and detection method to investigate the presence of E. sakazakii samples from eight of nine food factories and five of 16 households that contained the bacterium. In the accompanying commentary, Jeffrey Farber from Health Canada concludes: "Current industry efforts to reduce the occurrence of E. sakazakii have focused on improving hygiene practices, coupled with environmental monitoring and end-product testing for the organism. Since powdered infant formula is not sterile and there is the potential risk of contamination during preparation, there is a need for care when preparing and handling reconstituted powdered infant formulas. Health care professionals should follow recommendations provided by public health officials and organizations such as the American Dietetic Association," the editorial concluded, "and be alert to possible modifications."