NewScientist on Hwang
Despite their medical promise, stem cells have been dogged by political and ethical controversy because some are derived from discarded human embryos, and because of fears and confusion about links with human reproductive cloning. The future of stem cell therapies was thrown deeper into doubt in late 2005, when a leader of the field - Woo Suk Hwang, South Korea's stem cell king" - was found to have forged key discoveries and flouted ethical protocols. So has the stem cell miracle been postponed?
(...)
The most significant hurdle however, is immune rejection. As with any tissue transplant (from a donor other than an identical twin), the body will recognise ESCs as foreign and mount an attack which could destroy them. ESC recipients would have to take immune suppressant drugs for the rest of their lives.
Multiplying a patient's own adult stem cells in the lab and then reinjecting them is one way to avoid rejection. Duping the immune system is another possibility, perhaps using stem cells from the brain that somehow avoid detection.
Therapeutic cloning is a clever technique that circumvents the problem. We can make custom-made ESCs using a patient's own DNA and a donor egg. In the same way as reproductive cloning, the nucleus of a skin or muscle cell from the patient is added to an unfertilised egg that has had its own genetic material removed. This egg is then persuaded to divide as though it had been fertilised and, with luck, goes on to form the ball of cells called a blastocyst. At this point, the inner cell mass is removed and cultured in the lab to derive stem cells. These stem cells now contain the DNA of the recipient and would not be treated as foreign by the immune system.
But, in theory, the cloned embryo could be implanted into a womb where it might develop into a cloned human baby. This would be reproductive cloning, and is the same method used to produce Dolly the sheep.
(...)
In the place of a ban, US president George W Bush introduced legislation that restricted federally funded research to 22 stem cells lines created before 2001. However, research now suggests that these lines may have been tainted with material from mouse feeder cells in the lab, rendering them useless for human therapy. New ESC colonies free of this contamination have now been created.
(...)
Then in late 2005, the research community was rocked by claims that Hwang had flouted ethical guidelines by obtaining eggs from women in his own research group. As investigations proceeded and other transgressions unfolded, it became clear that much of his research had been fabricated. There are now questions over his use of funds too.
The fall from grace has been spectacular for a man who was revered as a national hero in South Korea, and the repercussions have travelled far and wide. Collaborating researchers have been tarnished by association, other stem cell science is under doubt, investors are wary of stem cell medicine, and there are now questions about how easy it is to fabricate results.
The already controversial field of stem cell research was brought further into disrepute, and it remains to be seen how much the scandal will delay the development of the miracle therapies that are so desperately desired.
(...)
The most significant hurdle however, is immune rejection. As with any tissue transplant (from a donor other than an identical twin), the body will recognise ESCs as foreign and mount an attack which could destroy them. ESC recipients would have to take immune suppressant drugs for the rest of their lives.
Multiplying a patient's own adult stem cells in the lab and then reinjecting them is one way to avoid rejection. Duping the immune system is another possibility, perhaps using stem cells from the brain that somehow avoid detection.
Therapeutic cloning is a clever technique that circumvents the problem. We can make custom-made ESCs using a patient's own DNA and a donor egg. In the same way as reproductive cloning, the nucleus of a skin or muscle cell from the patient is added to an unfertilised egg that has had its own genetic material removed. This egg is then persuaded to divide as though it had been fertilised and, with luck, goes on to form the ball of cells called a blastocyst. At this point, the inner cell mass is removed and cultured in the lab to derive stem cells. These stem cells now contain the DNA of the recipient and would not be treated as foreign by the immune system.
But, in theory, the cloned embryo could be implanted into a womb where it might develop into a cloned human baby. This would be reproductive cloning, and is the same method used to produce Dolly the sheep.
(...)
In the place of a ban, US president George W Bush introduced legislation that restricted federally funded research to 22 stem cells lines created before 2001. However, research now suggests that these lines may have been tainted with material from mouse feeder cells in the lab, rendering them useless for human therapy. New ESC colonies free of this contamination have now been created.
(...)
Then in late 2005, the research community was rocked by claims that Hwang had flouted ethical guidelines by obtaining eggs from women in his own research group. As investigations proceeded and other transgressions unfolded, it became clear that much of his research had been fabricated. There are now questions over his use of funds too.
The fall from grace has been spectacular for a man who was revered as a national hero in South Korea, and the repercussions have travelled far and wide. Collaborating researchers have been tarnished by association, other stem cell science is under doubt, investors are wary of stem cell medicine, and there are now questions about how easy it is to fabricate results.
The already controversial field of stem cell research was brought further into disrepute, and it remains to be seen how much the scandal will delay the development of the miracle therapies that are so desperately desired.
posted by Lawrence B. Ebert at 1:13 PM
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