9UNP0168SD_Derek_Hei_WordPress

- Welcome everybody, to Wednesday Nite at the Lab. My name is Tom Zinnen. I work here at the Biotechnology Center of UW-Madison. I also work for UW Extension, Cooperative Extension. And on behalf of the Wisconsin Alumni Association, thanks for coming to Wednesday Nite at the Lab. We do this every Wednesday night, 50 times a year. Tonight I'm delighted to be able to introduce Derek "Hay" to you. Excuse me, Derek Hei. He just corrected me and I have to get it right. 

Derek Hei works at the Waisman Center and for WiCell. He'll be talking about the National Stem Cell Bank here at WiCell and UW-Madison. Derek attended UW-Madison and received a Bachelor of Science degree in chemical engineering, graduating with honors in June, 1988. He then attended the University of California Berkeley, where he completed his PhD in biochemical engineering in 1993. Following his PhD research, Dr. Hei joined Genentech at South San Francisco in California as a scientist in the Process Recovery R&D group. At Genentech, he was primarily involved in developing processes and methods for producing and testing protein biopharmaceuticals. He then joined Cerus Corporation in May, 1994, where he established the Biomedical Engineering Group and directed the development of novel separation devices for transfusable blood products. The Biomedical Engineering Group at Cerus developed medical devices for treating transfusable platelets, plasma and red blood cells, and filed several patents based on this work. These devices are currently in Phase 3 human clinical trials. 

He came to UW-Madison in January 2000, to act as the Technical Director at the Waisman Center Clinical Biomanufacturing Facility. As technical director of the facility, Dr. Hei has been primarily responsible for facility startup, including: addressing design and construction issues, and equipping and staffing the state-of-the-art clean room facility for manufacturing biotherapeutics. What that basically means is we have a place on this campus where you can develop and test biopharmaceuticals, which is an amazing thing, if you're over at the Waisman Center. I don't know if you can actually go see it, but it's a rather unusual facility for a university to have. Currently, Dr. Hei interacts with UW investigators to address technical issues related to the development and production of cutting-edge experimental drugs for gene therapy, cell therapy and immuno therapy. Please join me in welcoming Dr. Hei to Wednesday Nite at the Lab. 
(applause)

- Thank you for coming out here tonight. It's a gorgeous night out there. So I guess I'm honored that you'd come in to actually listen to a scientific presentation. As Tom pointed out, the groups that I work with on campus are primarily involved in helping take the research that's done at the university and really translate it into potential therapeutics that one day, may help some of the people in this room. So I love that job. And I'm going to talk to you a little bit about some of the programs we have going on on campus that are really focused on trying to do that for embryonic stem cells. So I wanted to start out at a really basic level, because I wasn't quite sure how diverse this audience would be. I wanted to make sure that everybody was kind of on the same page, so I thought it was kind of fitting to start out with may be a thumb, and to zoom in on it and take a look at some of the cells that make up the thumb. And I guess the thing that has always amazed me about cells in the human body is that really when you look down at a very basic genetic level, and these are the chromosomes that are inside every cell, each cell in the human body has the same 46 chromosomes. 

And as the cells divide in the developing human, those chromosomes are reproduced, and exact replicates are divided into each of the daughter cells. Here you can see cells dividing. The chromosomes are stained in blue, and they'll be pulled toward these two daughter cells. And I guess the thing that's amazing to me is, just this basic question of if the cells all have the same genetic information, how is it they know to become a thumb cell, or a skin cell, or a heart cell or a brain cell. And that's a very fundamental question to developmental biologists. And it was a question that I think was very difficult to answer, and very difficult to do studies, for example, on really early human development up until the breakthrough discovery in Jamie Thomson's lab on this campus. And this happened in 1989. It was his first publication, regarding the derivation of embryonic stem cells. And this was a huge breakthrough, because it, for the first time, allowed us to look at human cells and to understand very basic issues of cell differentiation and developmental biology. And we'll talk a little bit about what that means. 

But essentially it's understanding how genes are turned on and off in a sequence to take the very beginning cells and make a brain cell or a heart cell. This is just a quick overview of where the embryonic stem cells came from in Jamie's original publication. Starting out with an early embryo or a blastocyst, there's a group of cells in the interior of this clump of cells called the inner cell mass. And he was able to coax those cells out and culture them in dishes. And you can see here an embryonic stem cell colony. It's growing on mouse feeder cells, was the original way they were grown. These mouse cells don't divide, but they produce something that supports the growth of the embryonic stem cell. And he developed this technique. And by using the right signals, you can expand these undifferentiated embryonic stem cells to very high numbers. And then by learning the chemicals cues that are used in human development, we can direct these cells to become glial cells in the brain, smooth muscle, macrophages, neurons, a variety of cells with potential applications. 

Before we go into talking more though, about how we differentiate these cells and what they can be used for, I just wanted to point out something about the embryos that were used in these derivations. This was some information that I got from Jeff Jones, who worked on the original derivation with Jamie Thomson. And I think it's kind of interesting information. Right now, or actually as of April 2002, there were roughly 400,000 embryos for IVF or in vitro fertilization procedures stored in the U.S. About 87% of those were destined for patient use. But about 50,000 really didn't have a clear designation, as far as what was going to happen to them. And here at UW, at the in vitro fertilization clinic, when couples go in and have an IVF procedure done, one of the things that needs to be decided upon up front is what will happen to the excess embryos. If they are successful in conceiving, there may be several embryos leftover, and what's going to happen with those embryos. And the thing that was I think kind of surprising to me really was that about 41% choose to donate their embryos for research and actually 29% choose to destroy their embryos. But I guess the thing that really surprised me was the low percent that really chose to donate to another couple. So I think this idea that these excess embryos could somehow be adopted by other couples is not really true. 

The couples that actually have these embryos created don't really want that, for whatever reason. And so these embryos, these excess embryos, there are a very significant number of them and their growing. Hopefully in the future, we won't need to use embryos. And we'll talk a little bit about the induced pluripotent stem cells that Jamie recently published on and discovered. And this might help to eliminate some of the potential controversy over the ethics regarding the use of embryos. But first, why embryonic stem cells. I just want to point out a few of the important properties that people may or may not be aware of. First of all they're pluripotent. They can essentially make any cell type in the human body. And that, of course, is important for being able to understand a variety of cellular processes and potentially creating cells that can act as a therapeutic. 

They're immortal. So as long as they're kept in an undifferentiated state, they can be expanded for months and months, and potentially years, to produce millions and millions of cells. And so that's important to note because, for example, certain adult stem cells have a very limited ability to replicate. These cells can be readily available for treatment. And we'll talk about how they might be used in a clinical setting. And finally, obviously, functional cells could be produced for potential therapeutic applications. So I'm just going to touch on a couple of ways that we use these embryonic stem cells and differentiate them into useful cell types. And this is really highlighting work of one of my colleagues at the Waisman center Su-Chun Zhang, a great scientist in the area of neurobiology. And this shows how he's using some of these cues to control the fate of the embryonic stem cells. And here in this first panel, you see undifferentiated cells and they grow in these colonies. 

This is many hundreds of cells that are very compact. And by using this cue of fibroblast growth factor two, and tissue growth factor beta, you essentially are giving it a signal that says don't differentiate yet. So these colonies can be expanded many, many times over to create these colonies of undifferentiated cells. And once you've made many cells, then you can add a signal to get them to differentiate into the cell type. And here I'm showing two of the types of neurons that Su-Chun has been able to differentiate the embryonic stem cells into, motor neurons which are the cells that are diseased in ALS or Lou Gehrig's disease. He uses Sonic Hedgehog and Retinoic Acid, two signals to get the stem cells to essentially differentiate into motor neurons. And then by using FGF8 and Sonic Hedgehog, he's able to make dopaminergic neurons. And these are the neurons that are diseased in people with Parkinson's disease. So two very important neuro-degenerative disorders, and one cell type that can potentially address both of them. There are a number of groups on campus that work on differentiating the cells into other cell types. 

And this is part of the National Stem Cell Bank that I'm going to talk about later, but one of our main focuses is understanding what factors effect the ability of the embryonic stem cells to differentiate into different cell types. And that might be effected by the procedure used to do the differentiation, what signals we're adding and what timeframe we're adding them in. It might be impacted in how we grow the undifferentiated stem cells or even differences between lines. We've seen significant differences between a line that might be derived in Jamie's lab versus one that may be derived in a lab in Singapore. And here I'm showing an example of beating cardiac cells that were derived in a differentiation study done in Tim Kamp's lab. And this is showing a beating outgrowth from what we call an embryoid body, which is a ball of differentiated cells. And clearly this beating outgrowth takes on a characteristic that is very reminiscent of a heart, and could potentially be used someday to treat patients that have suffered heart attacks. In the more near timeframe, they're looking at using these cells to screen drugs for cardiotoxicity. So this is something that will probably impact us soon and allow companies to identify drugs that might be very dangerous, to be eliminated and not used in humans. So we've talked about Su-Chun and Tim Kamp. 

In addition, John Odorico, a transplant surgeon at UW, has been looking at trying to do pancreatic differentiation, creating those cells to treat patients with diabetes. And Igor Slipven at the Primate Center has been doing differentiation of hematopoietic cells, so blood cell types. And he can make red blood cells, different white blood cells for treating a variety of things, cancer for example. So there's a long list of other investigators here at UW, but these are just an example of some of the work we're doing as part of the National Stem Cell Bank. And that really, as Tom pointed out in the introduction, is what my group focuses on. How do we take this research and get it to the point where it can be used as a therapeutic to help people. And I'm just going to talk about the three programs that I'm lucky to be involved in. The U.S. National Stem Cell Bank, WiCcell, and my group at the Waisman Clinical Biomanufacturing Facility. And all these groups currently are working on different aspects of this puzzle of how we will get these embryonic stem cells into human clinical trials. For those of you that aren't familiar with human clinical trials, I just wanted to put up this kind of timeframe, because I think that one of the things that we really need to be careful about is that a lot of people who look at these discoveries coming out of the lab, and they say you have beating heart cells, why can't we put them into a patient in another year? 

And the real reason is that the process of taking a therapeutic through human clinical trials that's really controlled by the food and drug administration is a very long process. It can take, as pointed out here, up to three years. Or I'm sorry, up to 12 years. Normally we go through a development process where we understand how to manufacture something. We make banks of cells. And we'll talk a little bit about this. And then do development of quality control methods and do some pre-clinical animal studies. And we file what's called an Investigational New Drug Application with the FDA. And that launches us into Phase 1. But you can see about eight years later, in addition to these human clinical trials, a lot of development work in parallel. 

But eight years later is when we would probably expect, at the very minimum, to be able to get a therapy out. And I think the thing that really is maybe a little bit shocking to people is that 12 years is over $800 million typically to get a therapy out to the public. And so it's a lot of cost and a lot of time. And I think we have to just keep perspective on what's going to happen with embryonic stem cells. We're still at the very early stage. As I said, I think some of the first companies are just at this IND filing stage for things like spinal cord injury and age-related degeneration. So I think it's going to take a while, but I think hopefully the public will understand that there are safeguards built in there by the FDA. And that's the reason for that. We certainly don't want to harm any patients when we go forward into clinical trials. So it's going to take a long time, but we've started working on this. 

And I just wanted to point out some of the hurdles that we're going to face in getting embryonic stem cells into the clinic. And some of these I think have been discussed somewhat out in the media. For example, the initial cells that Jamie derived were cultured on mouse feeder cells, they're called. I think you saw them in the first picture. And certainly that raises the question of could some viruses or other potential pathogens come from those mouse cells and contaminated his cell lines. That's a real concern that we've done some testing to demonstrate that that didn't happen. I'll talk about that a little bit later. Genetic stability of the cell lines is a major issue. I'll briefly touch on that. Freezing the cells, we've been working on as part of the National Stem Cell Bank. 

I've talked about selective differentiation. There's also concerns about residual undifferentiated cells. And of course, this is really similar to an organ transplant. If we transplant cells from one person to another, you have to worry about them being rejected. So these are all pretty significant issues that we have to address. So the National Stem Cell Bank is really taking on a lot of these issues and those are the issues on this slide that are highlighted in gold. We are establishing well characterized cell banks. I'll talk a little bit about that. And we're developing standardized quality control test methods. And I'll briefly discuss that. 

And finally, we need to develop processes for large scale production of cells for clinical applications. I'll touch on that briefly at the very end. So the U.S. National Stem Cell Bank is housed here at WiCell and UW. It was initiated in October 2005 with funding from NIH. And we are restricted to the NIH registry lines. And for those of you who aren't familiar with this term, President Bush in 2001, August 2001, put forth a mandate that said that cell lines that were derived before that date were the only cell lines that could be used for federally funded research. And at the time, there were 60-some cell lines. We're down to 21 now. But I think that that's one of the key points of the National Stem Cell Bank. We were limited by cell lines, but our job is to make sure that the cells that we do have are of the highest quality possible and that we do our best to understand what we can achieve with those cell lines. 

So I've listed the groups here that have cell lines. In addition to ESI in Singapore and BresaGen in Athens, Georgia, Cellartis in Sweden, Technion and Israel, UCSF in San Francisco, we here at UW have the five cell lines. And to date the National Stem Cell Bank has banked 19 of those 21 cell lines. And probably by the end of the summer, we'll have the last two from the Swedish group. And I think one of the things that we're proudest about is that from this bank, we have distributed orders, now probably over 700 orders, to over 350 labs around the world. About 10% of the orders going to Europe and Asia. So we're a bank for the U.S., but we're distributing not only cells, but information on these cells around the world. And really our goal is to help catalyze and accelerate science involving embryonic stem cells and the understanding of embryonic stem cells to help move us into the clinic more quickly. And really, those objectives are really summed up in this slide. It's not just a bank for distributing these cell lines, but also a group that scientifically is working on developing methods for characterizing the cells, standardizing methods for culturing and testing the cells, and really disseminating that information around the world to stem cell researchers, and finally even developing sub-clones or sub-cell lines from these 21 approved lines for regenerative medicine applications. 

- Is here the only stem cell bank in the world? 
- It is the only stem cell bank in the U.S. I think that right now the only other functional stem cell bank is in the UK. We work pretty closely with them. There is another bank that's starting to be developed in Singapore, but it's, I think right now the community as a whole is trying to understand what the best model is for kind of developing a network that will support the entire world. Because really, the point of view that the stem cell researchers have is that it's really important for us to get ethnically diverse cell lines and to be able to share those amongst groups will help us to be able to do that, especially here in the U.S., where we have such a diverse population. So I think with five cell lines it would be very unlikely that we would be able to get diverse enough lines to be able to get, you know, even partial matches with people that would decrease the likelihood of rejection. That's a good question. So this slide really outlines how we're doing the cell banking activities. Groups are depositing their cells. And we at WiCell create what we call Master Cell Banks or MCBs. 

These undergo very extensive testing, including testing for pathogens or adventitious agents. And I'm going to talk a little bit about that in the next slide. And then each of these Master Cell Banks, which might be a hundred vials that are frozen down. We produce distribution lots. So we'll go into our liquid nitrogen freezers and pull out a vile. And basically thaw those cells and start culturing them in dishes and continue expanding or passaging the cells. And eventually that one vial becomes another 100 to 150 vials that becomes a distribution lot. And those are the cells that we ship around the world to researchers. The distribution lot goes out to the researchers. And we finally do a characterization study where we take vials from the same distribution lot and grow the cells under defined conditions, and provide that information on our Web site so that the investigators that get these cells can get a good understanding of how the cell should behave, what they should look like. 

Are they normal from a karyotype or gene standpoint. So that's roughly what we're doing in our program. And I think one of the most important things that we do is creating these Master Cell Banks that are very well characterized. The testing for these will run somewhere around $50,000 to $70,000 per bank, because there's a very extensive amount of testing done. That's not obviously something every lab can afford to do. So by centralizing this activity and distributing those cells, we ensure that the researchers that are using the cells are using cells that haven't been contaminated or don't have any issues, for example, of being switched with other cell lines. So we do things like identity testing, a short tandem repeat. It's essentially a paternity test like you'd normally use if you were trying to decide whether a person is related to somebody. We use this on the cell lines in the exact same way. We look at cell recovery from freeze, how many cells survive when we thaw, and how many of them are alive. 

Growth characteristics, how fast did they grow? What do their colonies look like when they're growing, because sometimes they look a little bit different. And then most importantly we look for contamination that may have crept in over the years. They have been growing from people's labs, from either bacteria, fungi, microplasma. And really importantly, looking for potential pathogens that may have come from the mouse cells that they were exposed to when they were grown, or even from the human donors and other raw materials that came from animals. So lastly, one of the largest issues that we have in moving these cells forward is that as they're grown in culture, they do show issues with genetic stability. That's not really unusual for any human cell line that's grown in culture. So we've developed a variety of techniques that I'm going to discuss in the next slide for looking at genetic stability. And again this is similar to the slide that I showed in the very beginning showing the 46 chromosomes. But you'll notice some abnormalities in here. 

And embryonic stem cells, for whatever reason, like to get extra copies of chromosome 12 and 17. And it's very likely that those chromosomes have genes on there that for some reason, give them an advantage in growing in our dishes in the lab. We don't really understand why yet. It's one of the things we're trying to do more work on. It could be related to our passaging method, or how we divide the cells when we're expanding them. It could be related to the cryopreservation or freezing method. Or it could even be related to the media formulation that we use. The food that we give the cells may be not be fully optimized. So this is a big issue. We'd like to not have extra chromosomes in the cells. 

And this shows another way of looking at it. It was developed by Karen Montgomery who heads up the Cytogenetics Lab at WiCell. And this is a chromosome 12 from a cell that actually made a copy of the end of chromosome 12 and flipped it over. This is fluorescent in situ hybridization, so these are fluorescent probes that are made to the very end of chromosome 12. And you can see essentially it duplicated the end of the chromosome and flipped it over. So it's very likely that in this end of chromosome 12, which is what we see get duplicated a lot, there's some kind of gene that is allowing the cell to have a growth advantage. Because this cell when it gets this abnormal karyotype will eventually overgrow the cells in our dishes. So this doesn't always happen. It's something that with good culture practice, we can prevent. So I just wanted to finalize what the National Stem Cell Bank is doing by pointing out how we take this data and share it with the research community. 

We've established a Web site where people can go and, for example, order cells. And this is a listing of some of the cells that are in the bank. And people can request cell lines. And importantly, they can get very detailed information on each cell line. So, for example, we talked about Master Cell Banks. And this is a certificate of analysis for that. And it summarizes all the testing that we've done. It's truncated, it's not all shown here. But for each test, we put in a standard operating procedure that tells people how we did the testing. And it gives detailed reports. 

So instead of just getting a pass/fail, they can actually look and see what happened. And this is kind of unique. There have been a lot of groups that have done banking over the years. But this, I think, represents a higher level of sharing information with the scientific community to get a better understanding of how to test and characterize cells. So, really, one of the key goals of the National Stem Cell Bank. So that's about all I was going to say about the National Stem Cell Bank. And I just wanted to move on and talk a little bit, as we're winding up here, about addressing the issue of large scale processes for production of cells. And again this is really work that we do at the Waisman Clinical Biomanufacturing Facility. We manufacture cells for early stage human clinical trials. And so it's our job to understand how we'll make cells for use in humans. 

And in the early stages, growing them in dishes is an easy thing. We might have ten or 20 patients that we treat in Phase 1. By the time that we're into that Phase 3 trial that we saw on the timeline, we're treating thousands of patients. And we don't want the manufacturing process to change. So growing the cells in dishes really is not all that practical. We need to look at some other technologies. And some of the requirements we have are to get rid of the mouse feeders, the MEFs. We talked about why that's a problem, potentially transmitting pathogens to the cells. Normally, the cells grow adherent, attached in dishes. And I think in the lab you'll get to see some of that. 

There might be other ways to grow them so you don't even need to have them attached. Obviously, controlling the culture conditions to prevent or direct differentiation is key. And then monitoring conditions for GMP production. We'll talk about what GMP production is. It's regulations for clinical materials. It's a key thing. And we're really trying to develop two separate systems. One is a patient-specific method for deriving patient-specific cell lines. And in the future, it might be with Jamie's discovery of IPS cells, and we'll talk about this at the very end, that we would, in treating a patient, create a cell line specifically for each patient. And that requires a very different type of way to grow the cells, or method of growing the cells, than when we're trying to grow non-self or allogeneic cells. 

In that case, we would use a very large scale bioreactor. So these are the bioreactors we use at the Waisman Clinical Biomanufacturing Facility. We would use these for growing large quantities of cells to treat many patients. And this is an example of a robotic system that's being developed to grow cells specific for each patient. So patient-specific and large batches that would treat many patients. And on the bioreactor side, we have a project funded from the Wisconsin Institute for Discovery. It's collaboration with Tim Kamp again in medicine and Sean Palecek in the Department of Chemical and Biological Engineering. And really, the goal is to develop a profusion based bioreactor. And here's a picture of a small prototype that we're working with right now. And to optimize the conditions for growing the cells, really to control and prevent differentiation, or prevent the outgrowth of abnormal cells. 

Tim Kamp is also working on genetically modified lines that we can use to direct, to differentiate into cardiomyocytes. And really our goal is to, once we get the conditions worked out, to move into this large scale system that could essentially produce enough cells in a single batch to treat thousands of patients. So that's really our goal and we're just in the beginning stages of this. But we've been able to at least demonstrate that we're capable of growing cells in this small bioreactor. There's a small dish in here that's profused by this oxygenation vessel. And that we're able to grow normal cells. And so we're now working at modifying the media, the food that we're giving the cells, so that it's optimized for this configuration. And then we'll eventually move towards this large scale bioreactor. Then really, our final goal, once we have the bioreactor established, is to move it toward clinical production. Here's a picture of people growing a cell therapy in the Waisman Clinical Biomanufacturing Facility. 

I think in this case, they were growing skin for a local company that went into human clinical trials, and successfully went through Phase 1 and Phase 2 trials. Again, we would produce Master Cell Banks. And we would do it under what we call GMPs. These are the regulations that the FDA has for making materials for human use, current Good Manufacturing Practice regulations. So very strict guidelines on how we do things, like monitor this environment where we're growing the cells and document all aspects of growing the cells. And then eventually, we will file an Investigational New Drug Application and move it into clinical trials. So I just wanted to wrap up and hopefully leave enough time for questions, by just talking about a little bit about the induced pluripotent stem cells. And there might be a lot of questions about this. But I thought it was worth touching on. Induced pluripotent stem cells can be produced from, really, any cell type from a patient, as far as we know. 

The initial studies that were done were using skin cells, and were done both in a lab in Japan and Jamie's Thomson's lab here. So Jamie, two major breakthroughs in his lifetime. I think he's a great scientist. That's all you can say. So by introducing as few as four genes, they're able to take a skin cell and cause it to really go backwards in its development, and go back to a cell that looks like an embryonic stem cell. Absolutely amazing. So by doing that, they could take skin from a patient, make it go backwards to create an induced pluripotent stem cell. And then take it forward to make a heart cell. Or take it forward to make a brain cell. So essentially every person in this room could have their own cell line to treat whatever type of cell they needed for therapeutic application. 

This potentially addresses the ethical issues, because we're not using embryos, we're using skin biopsies that are coming from the donor. But the real question that I think we have to keep in mind is we don't know whether these cells are identical to embryonic stem cells. And there will be a lot of people that will say we don't need to work with embryonic stem cells anymore, because we have IPS cells. But I think that is not really firmly born out by science yet. We need to do enough studies to really understand whether IPS cells really are identical to embryonic stem cells. And there are other issues as well, for example, these genes that are introduced, what happens to them when they are turned back off and they differentiate. It might be that some of these genes will raise issues for potential use in a clinical setting. So this is just the beginning of IPS cells, we have to keep that in mind. So potential applications though, again, would be autologous cell therapeutics. Cell therapy specifically for every person in this room, where you wouldn't have to worry about rejection. 

And I think one of the other probably near-term potential that's really exciting to people is the ability to create IPS cells that are disease models. So we could take a skin biopsy from somebody that has a disease like Fragile X syndrome, make an IPS cell out of it and then differentiate it into a brain cell. And by doing that, perhaps get a better understanding of why it is that the genetic changes that are in patients that have Fragile X result in problems in brain development. So it's really potentially a very powerful tool for us to not only make therapies, but understand the disease and create alternative therapies that aren't based on cells. So a lot of potential there and I think that it's just the very beginning. So these are the groups that I again am privileged to work with at UW and WiCell. And on the WID Project that we have with WiCell and my group at WCBF. And I wanted to thank all of them, and open it up for questions. 
- Assuming there is a change in administration in the fall, and assuming that the prohibition against additional cell lines, how would that affect your work? 
- So, you know, I guess one of the questions is how will policy change in the fall. 

And I guess we really don't know that. It could be that it will be opened up to allow more cell lines than ones that are already derived. For example, I think Germany just passed a bill where they essentially took the date of August 2001, which is really pretty arbitrary, and they moved it several years back, and said okay we're going to allow anything that was derived before, and I don't know what the date is, but it might have been 2005, for example. But essentially it opens up several hundred new cell lines. And that obviously would be very useful for us, in that it would give us more diversity. We would be able to learn more. And it would be a big challenge for us to bank those cells, but it would be something that we would be looking at. If policy changes and we can derive new cell lines, I'm not really sure what will happen to be honest. There will probably be groups that will derive new lines specifically for clinical applications where they're very careful to not expose the cells to mouse feeder lines. That, for example, would be something that to me would be worth the ethical controversy that would come out of it. 

Yes? 
- If you didn't know who the donor was of an embryonic cell, how could you determine the ethnicity of that cell? 
- There are ways that you can. There are certain genes. Okay, sorry. So the question was, if you don't know the donor of a cell line, how could you determine the ethnicity if you wanted to? And that's a great question. Because of donor confidentiality, in fact, all the donors are really kept blinded. And the embryos come forward, and they're coded so we don't really know who the donors are. If you wanted to know ethnicity though, there are some ways that you can link other types of gene diversity testing to ethnic groups, for example. 

So a human leukocyte antigen matching that we use to decide what organs should go to what person, that statistically you could look at it, and sometime get a good feeling for whether that person is from a certain ethnic background. But more importantly that would be really what you probably want to look at for diversity. Because the HLA diversity is what determines whether you can potentially match a cell line partially to a person. That's a great question. Yes? 
- How are you able to verify that viruses from the mouse feeders weren't transmitted to the stem cells? 
- Okay, so how were we able to verify that potential pathogens from the mouse feeders weren't transmitted to the stem cells. That's a great question, as well. So there were a number of tests that we've done on the lines we've banked to date. And we do a variety of tests. 

A lot of the tests involve either tests in culture and animal studies. We'll take a sample of cells that we've grown up from the Master Cell Bank, and we will put them on some known cell lines. And we'll monitor those cell lines to see if viruses start to grow in those cells. We also take those cells and put them into mice. And we look to see whether the mice develop antibodies as they would in they had been exposed to a virus. And you monitor for a panel of antibodies for known mouse pathogens. And then we look for nonspecific viruses by, for instance, injecting those cells into Guinea pigs, and mice, and embryonated chicken eggs. And these are all standard tests that have been used over the years for all types of biotherapeutics that are produced in human and mammalian cell lines. Yes? 
- Can you bring us up-to-date a little bit on the status of clinical trials of stem cells. 

It seems wonderful and amazing that if you inject dopaminergic neurons into a Parkinson's patient, they will actually go where they're needed and form the complex connections, and take over for the diseased cells without going somewhere else, and messing it up, or becoming diseased for the same reason of the patient's original cells did. 
- Right. Okay, so the question is just kind of an update on human clinical trials, for example, in Parkinson's disease in particular. And I wish Clive Svenson were here. He could talk on and on about this. But, you know, I think for the reasons you mentioned, that the cells, if they're injected into the brain, are they going to connect up appropriately and really function appropriately. That's a challenging thing to do. And I think that's been the biggest hurdle for Parkinson's disease in particular. And so a lot of people are looking at, not necessarily replacing the cells that have died, but putting cells in that may produce growth factors that rescue and prevent further death of the dopaminergic neurons. So there's a couple of ways to approach it. 

That latter way, a rescue approach, is probably going to be an easier approach than actually replacing the dopaminergic neurons that died. Because, as you pointed out, they have to connect up appropriately. And if they don't, in fact, I think there can be some side effects that could be may be even worse than the Parkinson's disease itself. Dyskinesia, movements that aren't controlled have happened in patients that have received fetal cell transplants, for example. 
(inaudible)
 Right. So that's another thing. I mean, it's good to, I think, always keep in mind that growing cells in a dish and transplanting them into a patient, obviously that's a huge leap. And we have to, I think, constantly remind ourselves that when we talk to the public and we talk to patient groups, it's important to realize that there's a long way to go. But we're working on this as fast as we can. 

Any other questions? Yes? 
- I have heard that Wisconsin is a hot-spot for Parkinson's disease. Can you comment on that, and give any theories about why it would be? 
- So the question is, is Wisconsin a hot-spot for Parkinson's disease, and could I comment on it. And I wish I could. I don't really know much about epidemiology for Parkinson's disease. I just don't know enough about it to be able to really give you a good answer on that. Any other questions? Okay, well thanks again for, you know, it's a nice night out and coming. 

(applause)