By Stephen Young
By Stephen Young
By Stephen Young
By Jim Schutze
By Rachel Watts
By Lauren Drewes Daniels
One King comrade at the recent hearing was Amy Boswell, who carted her son Riley up to the podium and testified in favor of the ban, eliciting audible gasps from diabetics in the audience.
Getting down to the corporeal nitty-gritty of why embryonic stem cell research is wrong, most opponents present a simple secular argument: All that any petri-dish embryo needs to grow into an adult is time and nourishment. Boswell's analogy: "I have the potential to be an old lady," she says, "but you put me out in the desert with no food and no water and the poor conditions, I'm going to die...That doesn't make me any less human."
But advocates of the research note that human embryos cloned in petri dishes could never become grown humans based on current scientific knowledge. Birthing a clone would also require implanting an embryo in a human womb. "Oddly, a cloned embryo may be less ethically controversial once the facts are understood," says Arthur Caplan, a University of Pennsylvania bioethicist, "because it has the least potential to turn into an adult human being."
Regardless, opponents say, the research isn't even necessary. A handout distributed by Texas Right to Life points out a variety of problems with the cells, such as their tendency to form strange tumors consisting of clumps of teeth, eyes and hair. "Some scientists think that stem cells extracted from cloned human embryos will be useful for the treatment of human diseases," it says. These "claims are unfounded."
The view, a few years ago, admittedly might have been a Frankenstein mix of skin, bone and intestine cells--almost anything the cells wanted to form. But Geng has refined the mixture of proteins to direct the cells' growth. "These are heart muscle cells," he says, "derived from the stem cells."
Every second or so, the cells throb in unison. "The mature cardio cells are spontaneously beating; they have a pulse," Geng says. "It's like you grow a heart, in vitro, in a petri dish. A small, tiny heart."
Eventually, Geng wants to know whether embryonic stem cells can be grown into full-sized hearts for transplants. But in the near term, he's investigating how well the cells repair existing hearts. "What we want to do is find out how we can use embryonic stem cells and adult stem cells," he says, "and which ones can do better."
Adult stem cells so far have done a better job patching things up than embryonic cells. Despite Geng's ability to control the embryonic cells in the early stages, they often revolt once injected into the mice and form cancerlike tumors.
But Geng thinks he can overcome this hurdle. Research on embryonic cells is incredibly young--they were discovered in 1998--while adult stem cells have been studied for decades. Given more time, he says, he will be able to develop "molecular manipulation pathways" to guide the cells' development. "Using these techniques," he says, "we can selectively change these cells into heart muscle cells or vascular cells."
To Geng's credit, some of the shortcomings in his embryonic stem cell work are due less to science than to a lack of political support. Geng's embryonic cells come by necessity from one of the lines preapproved by President Bush, but those cells don't differentiate into heart cells as well as newer, unfunded lines of cells. All of the Bush-approved cells are also contaminated with mouse viruses and thus can't be used in clinical trials in humans.
"We need better stem cells," Geng says. "I hope that the Texas government can provide us with some funding for this."
Geng suspects that adult stem cells ultimately will face firmer limitations. So far, they've just been made to differentiate into only a small range of cell and tissue types, which means that researchers who want to grow a kidney from scratch or cure diabetes, for instance, might not be able to use them. And though adult stem cells work in patients such as Pavelko, they don't work in all patients, especially older ones, who lack enough stem cells in their bone marrow to harvest for treatments.
It's precisely this supply problem, in fact, that scientists believe could be solved with therapeutic cloning. An embryo cloned from a patient could yield plenty of new stem cells, which could form new, genetically identical tissue. The tissue could be implanted in the patient's body without being rejected by his immune system. "I believe this is one direction we could go in this century," Geng says. "I would say therapeutic cloning really will eventually prolong our lives."