This month, Sydney Spiesel explains and ventures an opinion about the latest in stem-cell research, parasite outbreaks, and cocaine consumption. He also updates some previously discussed topics. (Click here for the July and June roundups.)
Stem cells: New ways to make them, new ways to use them.
State of the Science: Like other mammals and most animals, humans begin as a single cell, the result of the fusion of egg and sperm. In the course of embryonic development, this first single cell divides and divides again and continues to divide. As time elapses, the dividing cells begin to take on individual characteristics: They acquire highly specific properties, and they lose some abilities, "differentiating" as they go on to become part of bone, brain, skin, and every other body part. The early undifferentiated cells are called "pluripotential" because they have the capacity to differentiate into every kind of cell in the body. Stem-cell therapy makes use of that capacity: In animal and some human experiments scientists have demonstrated that they can replace missing or misfiring differentiated adult cells and, in doing so, restore function to malfunctioning organs.
The politics: Stem-cell use is the most contentious issue in medicine these days—more contentious than really important concerns like cost and access to medical care and the impending risk of a worldwide influenza epidemic. Not all stem cells are derived from embryos. Until recently, however, the cells prepared from embryos were much more likely to work for research and therapy than the cells prepared from adult tissues. Using embryo cells raises religious objections; not using them raises objections about missed opportunities and waste.
Prognosis: The religious dilemma is here to stay. But this month, a report on stem-cell research using human umbilical-cord blood, by a team from Kingston University in Britain headed by Colin McGuckin, shed slightly more optimistic light on the possible use of stem-cell sources other than embryos. Until now, stem cells prepared from umbilical-cord blood were good as precursors only for the formation of blood cells, for example, in patients who can't make the blood cells because they're being treated for cancer. McGuckin's group for the first time used stem cells from umbilical-cord blood as precursors for tissue cells. Thus far, these results are limited to the liver; further research is needed to determine whether umbilical-cord blood can yield fully pluripotent stem cells.
Also promising: A report by Kevin Eggan of Harvard University describing a way to use embryonic stem cells to convert adult cells back into an undifferentiated state. This method could yield stem cells that are prepared from one's own tissues and thus less likely to be rejected by the body's normal defense mechanisms.
In terms of new treatments, Drs. Lee Ann Laurent-Applegate and Patrick Hohlfield and their collaborators report that they used human fetal cells to treat burns in children in Switzerland, with dramatic results. The treatment produced excellent cosmetic and functional results in all eight children on whom it was tested. * Also this month, some intriguing animal studies reinforced the hope that someday doctors will be able to use stem cells to repair damaged spinal cords and lungs.
Parasites: the not-so-innocent pleasures.
Outbreak: A summer romp in a Finger Lakes, N.Y., spray park during the brutal heat of August led to unexpected and mightily unpleasant illness for more than 3,000 people. The victims had stomach cramps, nausea, vomiting, and impressive diarrhea courtesy of a small parasite called cryptosporidium.
State of the Science: "Crypto" is probably the most common cause of waterborne disease in the United States and the world. The organism is extraordinarily hearty and easily survives even enthusiastic chlorination. It spreads from person to person via poop, as we pediatricians like to say. It's easy to transmit but hard to diagnose, treat, and eliminate. The Finger Lakes outbreak probably occurred because the spray park water is recycled, and the chlorination and filtration used to keep the water safe weren't up to the job.