Can adult Stem cells be substituted for embryonic ones?

As we noted earlier, multipotent cells can be found in some types of adult tissue. Recently a neuronal stem cell has been discovered in the human adult brain (from a part which was surgically removed for epilepsy). Do adult stem cells have the same potential as pluripotent stem cells? We thought not.

But perhaps we thought wrong. Recent studies with rats have shown bone marrow stem cells being able to produce liver cells. But at this time, the demonstration of the flexibility of adult stem cells has only been observed in animals and is limited to a few tissue types


Image : Human bone marrow. Note the predominant adipose cells with the Hoemopoetic cells scattered in between them. A  large megakaryocyte (Arrow) can also be seen. The centre shows a blood vessel filled with RBCs.

While adult stem cells hold promise, there are some significant limitations as to what we may or may not be able to accomplish with them. There have been arguments against these limitations too.-

1) Stem cells have not been isolated for all tissues of the body.
For example we have not located cardiac stem cells or adult pancreatic islet stem cells in humans.
Argument: Neither has this been done with embryonic stem cells!!

2) Scarce and difficult to isolate :
Adult stem cells are present in minute quantities and are difficult to isolate and purify. Their numbers may decrease with age.
Argument: This has been proved to be an underestimation. Canadian scientists have recently identified a way to make adult stem cells grow in the laboratory much in the same way as the embryonic cells do.

3) Acute disorders and genetic conditions:
 Using stem cells from patient’s own body means obtaining adequate amounts by growing them- the time may be a big factor in acute disorders.- If the disorder is due to a genetic defect, the same defect may be present in the person’s stem cells too.
Argument: But that is precisely what has been done by the same researchers in the name of “gene therapy”

4) Proliferation :
Stem cells from adults do not have the same capacity to proliferate as embryonic stem cells.

5) DNA damage:
Adult stem cells may contain more DNA abnormalities caused by exposure to sunlight, toxins etc

6) Limited research possible : Research on early stages may not be possible with pluripotent adult cells.

7)There is no direct evidence that human stem cells are pluripotent except that they have been able to produce two to three types of cell lines.

Isn’t that enough to make you sigh at Bush’s decision?

The Ethical Conundrum :

The ethical issues involved are making this issue blow up in geometrical proportions.
So let’s hear the “for”s and “against”s.

Anti- stem cell research
The prospective benefits of stem cells should not and cannot justify the method necessary to obtain them. Embryos have as much right to live as we do and just because they have no form, gives us no right to destroy them. When we can work with adult cells, why use embryonic cells.

 
"A free and virtuous society, which America aspires to be, must reject practices that devalue and violate human life at any stage from conception to natural death." The Vatican later clarified the statement: "The moral condemnation also regards procedures that exploit living human embryos and fetuses."  

- Pope John Paul 

Pro- stem cell research
Embryos are genetically human beings but they do not have the same moral relevance because they lack specific capacity, including consciousness, reasoning and sentience. It is immoral to discourage such cutting edge technology as it has the potential to save many lives.

"I think that federal support of embryonic stem cell research is a pro-life, pro-family position. This research holds out promise for more than 100 million Americans suffering from a variety of diseases including heart disease, multiple sclerosis, Parkinson's, Alzheimer's, ALS, cancer and diabetes. ... After careful consideration, thought, prayer, and study, this pro-life senator has concluded that federal support of embryonic stem cell research is appropriate."

-Senator ______ Hatch of the US house of representatives