Stem Cells: Potent Potential

Disease Cures Possible With Embryonic and Adult Stem Cell Research

October 27, 2004

Cures for Parkinson's disease, juvenile diabetes and Alzheimer's disease may be within grasp for scientists in California if a stem cell research initiative on the November ballot passes.

Proposition 71, the California Stem Cell Research and Cures Initiative, would give scientists the green light to conduct federally-funded research with stem cells, human cells that can generate new cells and tissue.

However, embryonic stem cell research, the specific type of stem cell research with the potential to cure chronic diseases, remains at the center of ethical debate. Embryonic stem cell research requires cells to be extracted from a fertilized egg, or embryo.

Some researchers at UC Berkeley have chosen to experiment with another type of stem cell: adult stem cells. Adult stem cells are present in the organs of the body, including the brain, heart, and fat, and can differentiate, or develop, into a limited number of cell types.

At bioengineering professor Song Li's cell and tissue engineering lab, UC Berkeley graduate students study mesenchymal stem cells, or adult stem cells from bone marrow. Li's goal is to discover and manipulate the chemical and physical environments that would allow stem cells to differentiate, and use those engineered cells and tissues for tissue repair and regeneration.

"In general, cell engineering and tissue engineering provide alternative approaches for organ transplantation, and stem cell engineering holds tremendous potential,' Li said.

Stem cells could be used to construct skeletal muscle to cure muscle dystrophy or blood vessels for bypass procedures.

Some research team members have been working on creating biological replacements for arteries, so patients with clogged arteries could use blood vessels created from stem cells instead of man-made stents or angioplasties.

And with cardiovascular disease as one of the leading causes of death in the United States, these developments could be crucial for the 61 million Americans with some form of the disease.

"Replacing diseased blood vessels and regenerating heart muscles using a stem cell engineering approach will definitely benefit healthcare," Li said.

However, adult stem cells have a predestined fate. Blood stem cells, for example, cannot differentiate into nerve or pancreatic cells -- they can only differentiate into their own cell type.

Scientists see potential in embryonic stem cells, which are able to develop into almost every human cell type. With embryonic stem cells, it would be possible to take cells from one part of the body to repair another part. But because of a low supply of cell lines -- cell cultures that can multiply in the lab -- and government restrictions on embryonic stem cell research funding, there has hardly been research of this kind.

The heart of the debate lies here: embryonic stem cells are obtained from the blastocyst, an early embryo that has not yet implanted itself on the uterine wall.

"The problem is some people think that the embryo is a living being, other people think that embryo is a clump of cells," said molecular and cell biology professor Randy Schekman, who is also chair of the chancellor's advisory committee on biology.

The blastocyst is a ball of cells with a hollow center. Lining the interiors of the blastocyst is the inner cell mass, which is where embryonic stem cells are located. To obtain embryonic stem cells, the inner cell mass has to be separated into single cells and placed on a petri dish with nutrients. If the cell grows and divides to form a colony, it is a stem cell.

Schekman says a couple of dozen stem cells could potentially be obtained from one embryo, but in practice only one or two can grow colonies.

In order to develop embryos that are tailored to a specific genetic composition, scientists are interested in a method called somatic cell nuclear transfer. First, an egg's nucleus is removed. It is then replaced with another nucleus from a somatic, or body, cell, which would have the same genetic program of the patient. The somatic cell would then be stimulated to work like a fertilized egg cell. This is also another point of contention, as this method can also be used for human cloning.

Still, scientists argue embryonic stem cell research has many possibilities.

"We can learn more about the embryonic development of humans, we can learn about genetic diseases," Schekman said.

It may also be possible to study how genes produce tumors. The possibilities with this type of research, Schekman says, are very applicable to the human situation.

Contact Andrea V. Hernandez.

Copyright © 2004 The Daily Californian.

This article posted Decembere 1, 2004.