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Stem Cell Research



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ANNOUNCER: Brought to you in part by ADM, feeding the world is thebiggest challenge of the new century, ADM is promoting soilconservation, so history doesn't repeat itself. ADM, supermarket tothe world. Additional funding is provided by the John M. OlinFoundation, the Lilly Endowment, the Lynde and Harry BradleyFoundation, and the Smith Richardson Foundation.

(Musical break.)

MR. WATTENBERG: Hello, I'm Ben Wattenberg. Stem cell research isat t cutting edge of today's biotechnology revolution. It opens uppossibilities for curing diseases such as Alzheimer's, Parkinson'sand diabetes. But, along with this potential come some ethicalconcerns. Joining Think Tank to examine the field of stem cellresearch are John Gearhart, professor of gynecology obstetrics atJohns Hopkins University School of Medicine, Dr. Robert Goldstein,vice president of research for the Juvenile Diabetes FoundationInternational, and Ruth Macklin, a professor of bioethics at AlbertEinstein College of Medicine. The topic before the house, stem cellresearch, this week on Think Tank.

(Musical break.)

MR. WATTENBERG: Stem cells are found most commonly in embryos andfetal tissue. They are undifferentiated cells, that is, in effect,they're blank. This means they have the potential to grow and matureinto many different types of adult cells, including bone tissue,muscle tissue, skin or blood. Recent breakthrough experiments haveshown that scientists can program these blank cells to becomedifferentiated cells, and other specialized tissues. But, there areethical concerns involved. One of today's guests, John Gearhart, leda team at Johns Hopkins University that extracted stem cells fromaborted fetuses. Now there is a ban on federal funding for humanembryo research. This ban until now has removed the federalgovernment from the controversies over abortion and geneticengineering, the basic breakthrough research has been done in theprivate sector. But, now the Clinton administration has opened upthe possibility for some government role in stem cell research. Whatbenefits can we expect from such research? Do these benefitsoutweigh any ethical concerns? To answer these and other questions,we turn now to our expert panel Ladies, gentlemen, thank you somuch. Because your friendly moderator, and millions of otherAmericans don't understand a whole lot about this field, and it getsquite complicated, I thought we might begin by trying to understandwhat it is we're talking about, Dr. Gearhart.

DR. GEARHART: Well, stem cells are very unique types of cells. They are cells that have two properties, one is that they can renewthemselves in a tissue culture setting, in a laboratory setting wecan have cells in a dish that will produce more cells likethemselves. And under appropriate conditions these cells can formvirtually any cell type that you find in the human body. And what weare trying to do currently is to determine how to make them form aspecific cell type. But, I think you can now appreciate the power ofthese cells. That you can have an endless supply of them, andvirtually you can form any cell type that you find in the human body.

MR. WATTENBERG: Are they harvestable only from fetuses, andembryonic material?

DR. GOLDSTEIN: You can recover stem cells from a variety ofsites, including embryonic material, as well as from mature people. There are great differences, however, between cells recovered in theembryonic form versus adult or mature stem cells in terms of functionand ability to become other cell populations.

MR. WATTENBERG: Ruth Macklin, just sketch out for us briefly whatthe two poles on the ethical argument are about this situation?

MS. MACKLIN: Well, one pole on the ethical argument focuses onthe embryo, and since the fetal tissue comes from already abortedfetuses, that's not as much of a concern. The opponents of using --deriving stem cells from embryos argue that these are living humanbeings, and therefore the ethical issue solely revolves around theuse of those embryos. On the other side, however are the greatbenefits that are potentially available from the research that is nowbeing done, or will be done using stem cells, benefits to untoldnumbers of people, with a great variety of diseases. So it'simportant not to focus the ethical issue only on the use of theembryos, but also to look at the great benefits that can come fromthe research.

MR. WATTENBERG: You've recently done some very importantresearch, if I understand it correctly. Could you sort of sketch itout for us, and then please let's open up the conversation.

DR. GEARHART: Sure, what we have done is to isolate certain cellsfrom aborted fetal material, and the procedure for this is very muchthat the investigators who are using this material have no influenceor impact in any way on the decision to have that abortion.

MR. WATTENBERG: I understand.

DR. GEARHART: And the mechanisms for obtaining that are quitelengthy, obtaining tissue. We then isolated specific cells from thattissue, placed it in a laboratory environment, in which we thencultured these cells.

MR. WATTENBERG: In a petri dish?

DR. GEARHART: In a petri dish, absolutely. It grows in anincubator and we learned then that these cells that we had isolatedhave the developmental potential to form many of the cell typespresent in adult human beings.

MR. WATTENBERG: How could you -- I mean, it sounds to the layear, I mean, incredible. How do you tell it to become a nerve cellor become a kidney, or whatever?

DR. GEARHART: I wish I could say, hey, you there. I wish we knewthe answer to that. We know a little bit of the answers, and this iswhere the work now must go, and for which we feel the federalgovernment should have a role I funding. We can nudge, encourage, atthis point these cells to become specific types of nerve cells.

MR. WATTENBERG: How do you do that?

DR. GEARHART: We treat them with different types of chemicals,called growth factors, that we know about from our colleagues who arestudying development in embryos. We know that a cell -- a cell'sfate in an embryo is really determined by what it sees in itsenvironment. And if you can mimic what's in a cell's environment ina petri dish, what is normally in an embryo, you can then influencethat cell to become a neuron or a muscle cell.

MR. WATTENBERG: You work with kids who have diabetes?

DR. GOLDSTEIN: Yes, we are trying to support research to find acure for type 1 diabetes that occurs in children.

MR. WATTENBERG: Which is one of the more serious forms?

DR. GOLDSTEIN: Correct. And these children have no beta cellsfrom their pancreas, which are the cells that secrete insulin. Sobecause the immune system destroys those beta cells in the children'spancreas, they have to take life-long insulin injections. Theproblem is that the immune system keeps attacking other systems. Soif I give a child insulin, that does not cure diabetes, and thesechildren still can have the complications of eye damage, kidneydamage or nerve damage.

MR. WATTENBERG: Even if they keep up their insulin treatment?

DR. GOLDSTEIN: Even if they keep up their insulin. This is notwidely understood. The simple fact is that insulin is simply thehormone that takes care of glucose metabolism. The disease of type 1diabetes is an autoimmune disease, where the immune systemmisbehaves.

MR. WATTENBERG: I don't want to scare a lot of people out in theaudience. Kids with juvenile diabetes now can live --

DR. GOLDSTEIN: They do very well.

MR. WATTENBERG: They can live a pretty -- and it's quite aremarkable medical achievement.

DR. GOLDSTEIN: It's a very remarkable achievement, it justdoesn't cure the disease, so that they still have some side effects.

MR. WATTENBERG: Right.

DR. GOLDSTEIN: Now, the excitement about the potential for stemcells is that if one could instruct stem cells to make the beta cellsof the pancreas, and secrete insulin we could give them to thesechildren. We'd have to do a few research steps. We'd have to makesure that they resisted rejection, and they resisted attack from theimmune system. But, these things are today possible.

MR. WATTENBERG: Let me ask you a question, and we have a piece oftape from a woman named Diane Irving, who says that you can use adultcells.

MS. IRVING (From video): Almost all of the diseases that arediscussed, in terms of the benefits that would help patients, benefitpatients with these diseases, it can all be done with more maturestem cells. So there's no need to use stem cells derived bydestroying living human beings.

MR. WATTENBERG: We can discuss the living human being thinglater, but what about the idea of if there is an ethical argumentabout using embryonic material, and you can get stem cells from anyone of the four of us, I assume, and the gang around here, why notuse -- and then you would overcome the autoimmune --

DR. GOLDSTEIN: There is no scientific basis for the statementthat you can get all of the stem cells to work and function fromadults.

MR. WATTENBERG: I see.

DR. GOLDSTEIN: In fact, the science contradicts that. Forexample, the beta cell studies, in animal experiments and even insome human experiments, actually says that the earlier cells, theless mature cells reduplicate, remain in the dish, grow, proliferate,and function many, many, many times better than the adult version.

MR. WATTENBERG: But, you would have to overcome the immune systemby transplanting into another --

DR. GOLDSTEIN: A way to overcome the immune system is to takethat young population of cells, in what's called cell engineering, orinstruct it to have resistance factors, so that when you dotransplant it you won't have rejection.

MR. WATTENBERG: Let me ask a really stupid question, if I might. I mean, if I wanted to get a stem cell out of my hand, what would Ido? You take a tissue sample and --

DR. GEARHART: The stem cell you would take out of your hand, oroff the skin of your hand, would produce only skin type cells. Itwould not produce a wide variety of different cell types. And sothis is the importance, I think, of the embryonic stem cell, is thatthat cell is capable of essentially producing bone, cardiac muscle,neurons, on and on. These cells that you would take have much morelimited developmental potential. Embryonic stem cells were isolatedabout 20 years ago, in mice. And what we are doing from the humanside are following on essentially 20 years of experimentation onthese cells, in an animal system. And all that we are doing isapplying to what has already been applied, and has been demonstratedin an animal system with these human cells. For example, these cellshave been isolated from the mouse, grown in culture, differentiatedinto cardiac muscle, neurons, blood cells, and then transplanted backsuccessfully into adult mice.

MR. WATTENBERG: Into another mouse?

DR. GEARHART: Yes, another mouse, where they --

MR. WATTENBERG: Lots of mouses.

DR. GEARHART: Where they have functioned normally. So the proofof concept is there.

DR. GOLDSTEIN: And let me just emphasize, if you can constructcells for secreting insulin, and put them into children and curediabetes, and you can produce cells that can replace damaged heart,and you can produce nervous system cells that can restoredegenerative nerves, as in Alzheimer's and Parkinson's, and you canproduce cells that can effectively replace bone marrowtransplantation in children with cancers, and you can produce cellsthat can restore marrow function in children with immunodeficiencydisorders, and overcome them, the clinical potential isextraordinary, particularly as seen by parents of children, andindividuals who are afflicted. All of the scientific data, as Dr.Gearhart has described, comes from following the typical pattern inscience. You work from the test tube to the laboratory animal, tothe person. We are now, after 20 years, on the brink of going topeople, with a terrific version of how to accomplish that treatment.

MR. WATTENBERG: Is this -- is this biotech, is this geneticengineering, or is this sort of a subset of that?

DR. GOLDSTEIN: It's a combination. In other words, the cells --some cells all by their lonesome may or may not have characteristicsthat you would like to have. So, for example, if I want to restorebone marrow and transplant a child with leukemia, so I can cure theleukemia and then give them a normal life, I need to instruct thosecells to resist certain toxic events, or even to resist a recurrenceof the leukemia. That's cell engineering.

MR. WATTENBERG: What's the timetable? I mean, roughly speaking,if somebody has Parkinson's today and is sort of in the early stagesof it, and I don't know what the time span is, within 10 years, 7year, 5 years, are you going to have something?

DR. GOLDSTEIN: I hate to promise timetables, but the excitementis that some of those experiments have already been taking place. Sowhat's lacking is an expansion of the research, and the clinicalapplication.

MR. WATTENBERG: Experiments have taken place and been successful?

DR. GOLDSTEIN: And reportedly have been successful in smallnumbers.

MR. WATTENBERG: What would that do to a Parkinson's patient?

DR. GOLDSTEIN: It should restore nervous function, as long as thecells can replace and replenish that particular function.

MR. WATTENBERG: Have you seen it in a mouse with Parkinson's, gofrom Parkinson's to non-Parkinson's?

DR. GEARHART: That experiment was not done in a mouse.

MR. WATTENBERG: No, but I mean, if you had a mouse and itsuffered from disease X, and you did X, Y, Z to it, can you give mean example of a mouse that was cured of something?

DR. GEARHART: Yes, we can actually take and transplant back intoan animal that has lost its blood system, through irradiation, andits ability to produce white cells and red cells, and havetransplanted back stem cells derived from embryonic stem cells thathave absolutely reproduced in that animal, and has rescued theanimal. Cardiac muscle, an injury to the heart, cardiamyacites (sp)have been placed in those heart lesions and they have functioned. Now, there's another animal model that is very interesting forstroke, in which a very similar type of embryonic cell has beenplaced into the lesion site where the stroke occurred, and theseanimals have recovered a good deal of function, and that has now beencarried into clinical trials in humans.

DR. GOLDSTEIN: Part of the timetable problem is we need to takethe current observations and move them along. So we have to find outhow to signal with the chemicals the differentiation of the stemcells to produce heart cells, nerve cells.

MR. WATTENBERG: Do you have a timetable in mind, ballpark, rough? What are we -- are we talking about a year, a decade or a centuryfor this stuff to happen?

DR. GEARHART: I would hope a decade, and I think it's going to bevery much cell type specific. I think Parkinson's would be one ofthe earlier ones, to be honest with you, because we know more aboutyou take a neural stem cell and have it differentiate into adopaminergic (sp) neuron, which is a big term for that specific typeof neuron.

MR. WATTENBERG: Could this be used for a person who was, say, aparaplegic, because the nerves were shattered or cut?

DR. GEARHART: Well, spinal cord injury is another target here, toproduct the big motor neurons that are necessary, and absolutely. Absolutely.

MR. WATTENBERG: Good luck. Now, Ruth, let me direct this to you,but let me begin by putting one other clip on from Diane Irving who,as I said before, is a former biochemist at NIH, and a philosophyprofessor at the Dominican House of Studies. And she had this to sayabout the ethical issues involved with stem cell research.

MS. IRVING (From video): Stem cell research, where the source ofthe stem cells is through a destruction of living human beings, inorder to help other human beings, would be unethical.

MS. MACKLIN: What counts as a living human being is subject tointerpretation and to many different views. On the one hand, you'vegot the view stemming from some religious groups that a fertilizedegg is a living human being, just like us and our viewers. On theother extreme, perhaps even more extreme, you have not until sometime after birth do you have a person with all the rights of persons. So there is by no means a single view, ethically or religiously,about when a living human being begins. Most of the major religions,in fact, do not define living human being as an embryo or afertilized egg. So let's set that aside and say, that's acontroversial definition. Now, so we're now talking about theembryo. In the case of the fetal tissue, the abortion has alreadybeen performed, there is a separation between the time at which thewoman consents to the abortion, that is, grants her informed consent,her request to have an abortion, and a second later time in which thewoman would then be asked, would she permit the use of the abortedfetal tissue to derive the stem cells for research purposes. Soessentially there is a time lapse, and the woman who was having theabortion is not in any sense having the abortion for the purpose ofusing those cells. The case of embryos, whereas it is true that theembryos are alive, or would have a potential for life at the timethat the stem cells are derived, it's very important to recognizethat the embryos that are being proposed, at least according to theguidelines that are coming out of the National Institutes of Health,those embryos are embryos that would never be implanted, and hencenever --

MR. WATTENBERG: Why not?

MS. MACKLIN: Why not, because first of all what people mustrecognize is that there are tens of thousands of frozen embryos,cryopreserved, they're called frozen embryos that are excess, meaningin excess of clinical need. The couple that produced those embryosis never going to implant them, they're never going to be used forother couples, as a kind of embryo adoption, and therefore it's aself-deception on the part of those who look at the embryos thatwould be used for this research purpose, self deception to say theseare living human beings. These embryos are never going to beimplanted.

MR. WATTENBERG: Let me ask a question, is it possible in thefuture when a baby is born to harvest some stem cells so that 40years later or 50 years later if it needs a kidney it gets its ownkidney, without it going through the autoimmune process?

DR. GEARHART: Something close to that is being done now, theumbilical cords are being saved, and they are a source of stem cells,but mainly the blood stem cells. I don't know that we can harvestfrom a newborn a version of an embryonic stem cell that would produceall cell types.

MR. WATTENBERG: Let me just come back to what you were sayingbefore. I happen to be on the pro-choice side of this life-choiceargument. But, it's a close call, and it's a very troubling matter. I know some people who are also pro-choice, in some cases vigorouslypro-choice, who have gone through the in-vitro stuff, and when itcame time or even to think of the idea of diminishing eight potentialembryos down to two or three or whatever you implant, couldn't faceup to it, or had enormous -- how old? I mean, when you're usinghuman fetal stem cells, how old are they?

DR. GEARHART: Well, our experiments use five to eight weeks postfertilization, so they're --

MR. WATTENBERG: So they've been --

DR. GOLDSTEIN: The question of the concerned couple, we are allconcerned about how cells are derived. But, the simple fact, as Dr.Macklin said, that there are available cells that are inrefrigerators, not being used for any purpose whatsoever, that couldprovide the source material under, you know, strict guidelines andguidance, to begin the research that's needed to get to the nextstep.

MS. MACKLIN: And furthermore, the -- let's go back to how peoplefeel about this, which you pointed out. No cells would ever bederived from any embryos without the source of those embryos givingpermission. These are things about which reasonable people disagree. And there are many Americans who, knowing that they're not going touse those embryos, would give permission to have the cells derivedfrom the embryos. These are the choices that people are given whenthey have frozen embryos. They can keep them in storageindefinitely, and which they're never going to be human beings in anysense of the word, other than as defined by those religions, or theycan be donated to other couples, who would like to have a childthrough assisted reproduction, or they can be destroyed, or they canbe used for research. That's it.

MR. WATTENBERG: Okay. The other side, we stipulate is not fullyrepresented here. But, we've at least put that out. Now, just towrap this up, how big is this? How important is this medically? Imean, there is so much else going on in the biotech world, is thisthe key to unlock a huge panoply of cures?

DR. GOLDSTEIN: It's huger than huge in potential, which we'llnever fully understand until we progress and do the research. Sothat for diabetes it offers tomorrow morning a genuine possibilityfor a cure. And if we do the research in the next five years, Iwould argue that from year six through ten we'll be in the clinictreating people with cells that can restore. We can replace andrestore bone marrow tomorrow morning, if you had the appropriatecells, like the mouse model that Dr. Gearhart talked about, and youcould take care of an enormous number of children with leukemia andother cancers. You can change the face of children with unique,congenital immunodeficiency disorders, and in effect cure them withthis kind of cell treatment. So that of all the things that youcould argue tomorrow morning would be out in front, we would say thismay well be number one in terms of potential. And just like we callit research is exploring the unknown, we'll have to prove the point. But, to open the door for the research with this kind of potentialmakes an enormous amount of sense to us.

MR. WATTENBERG: All right. I think that pretty well says it. And we are out of time. Thank you, John Gearhart, Ruth Macklin, andRobert Goldstein. And thank you. We encourage feedback from ourviewers by email. It is very important to us. For Think Tank, I'mBen Wattenberg.

ANNOUNCER: We at Think Tank depend on your views to make our showbetter. Please send your questions and comments to New River Media,1150 Seventeenth Street, Northwest, Washington, D.C. 20036, or emailus at thinktank@pbs.org. To learn more about Think Tank, visit PBSOnline at www.pbs.org. And please let us know where you watch ThinkTank. This has been a production of BJW, Incorporated, inassociation with New River Media, which are solely responsible forits content. Brought to you in part by ADM, feeding the world is thebiggest challenge of the new century, ADM is promoting soilconservation, so history doesn't repeat itself. ADM, supermarket tothe world. Additional funding is provided by the John M. OlinFoundation, the Lilly Endowment, the Lynde and Harry BradleyFoundation, and the Smith Richardson Foundation.

(End of program.)

 

 

 



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