Cracking the code

An American researcher at Ghent University, Thomas O’Leary (pictured) is in the final stages of completing his PhD, which focuses on the origins of human stem cells, looking into the process of how they are created in embryos. “Until now, everyone thought that human embryonic stem cells were generated directly from the inner cell mass of the embryo,” he explains. “Our paper reveals that the inner cell mass transforms in vitro before the stem cells arrive. Essentially, we’ve discovered a new stage.”

The article “Tracking the progression of the human inner cell mass during embryonic stem cell derivation” was recently published in Nature Biotechnology, one of the most widely read and influential scientific journals in the world. This research, done in collaboration with Leiden University Medical Centre in the Netherlands, is indicative of the university’s scientific aspirations.

Professor Petra De Sutter, head of the Department for Reproductive Medicine at Ghent University Hospital, has every intention of continuing to aim high. “From an infertility treatment perspective, our long-term goal would be to create gametes [an egg or sperm] in vitro so these infertile couples could have a child with their own genetic make-up.”

Curing infertility is one of many dream scenarios posed by stem cells, an area of research that has captured the imagination of scientists and the public alike. Whether it’s a spinal cord injury that has left someone paralysed or a debilitating degenerative disease like Parkinson’s, stem cell research has instilled a hope so strong it’s nearly tangible.

Stem cell research is complex and multi-layered. “Stem cells have two unique traits,” explains O’Leary. “One is self-renewal, so they can be grown in culture indefinitely. The second trait is pluripotency, which means they can be directed to differentiate or to develop into any of the adult cell types in the body, such as heart or liver cells. This is interesting for scientific research because it makes them applicable to all biological fields.”

"For instance, if you are studying the lung," says O’Leary, “you can take stem cells and drive them to become lung cells, instead of working with a live organism, such as an animal or human. Right now, there is a US company differentiating stem cells into retinal cells. These are cells of the eye. Their work is showing promise for treating macular degeneration. In other words, this is a clinical trial for curing a type of blindness.”

Yet for all its promise, there is a shroud of mystery and serious concerns about ethics tied to this topic. Stem cells are, after all, harvested from human embryos.

Kinds of stem cells and where they come from

There are a few ways of obtaining stem cells. There are adult stem cells (such as Hematopoietic, found in bone marrow), but once these cells have a lineage, this is the only purpose or direction they can have. While they can still self-renew, they no longer have pluripotency.

There are induced pluripotence stem cells (iPSC), which are artificially derived by forcing non-pluripotent cells to become like human embryonic stem cells (hESC). While they show a lot of promise, iPSC are only trying to be like hESC, but are not yet an exact match. This could be the future of stem cell research as the field develops, but, for now, hESC are the gold standard.

Most embryonic stem cells used for research are obtained from embryos that have developed from eggs fertilised in a lab in vitro. A strong in vitro fertilisation programme in Flanders is the source of many donated embryos. Stem cell extraction is only done with full consent of the donors.

Opinions – both from members of the public and from couples undergoing treatment (a major source of egg donations) – are divided depending on how people see embryos, says professor De Sutter. “If it’s a miniature child, then they can’t allow the research. If it’s a clump of cells without any potential, then research is fine. That is the core of the discussion.”

Professor Karen D Sermon, head of the Department of Embryology and Genetics at the Free University of Brussels (VUB), says she “wouldn’t be doing this if my thoughts weren’t clear. Is it ethical to use eight or 100 cells, or clumps of cells, for research for the betterment of patients and their children? I’ve been working with human embryos and hESC from the first day of my PhD. It is not a person and doesn’t have the same rights as a person.”

Legal restrictions and ethical committees

Professor Catherine Verfaillie, head of the Stem Cell Institute at the University of Leuven (KUL), which uses embryonic stem cells but doesn’t create them, says the decision to not make embryonic stem cells has to do with logistics. “We could make them, but the VUB lab is nearby, and it didn’t make sense to have two labs in the same vicinity focusing on the same thing. KUL has no objections, ethically or morally, regarding this.”

The law seems to agree. Flanders is at the forefront of hESC research for two reasons, and one of them is legality. “The 2003 law that regulates embryo research in Belgium allows us to do a lot of great work,” says Sermon. “But it is also very clear: Both the scientists and the patients are protected. You have to ask for permission for any work you want to do, which takes time. But this is a small price to pay. You can do the research as long as you follow the rules.”

Professor De Sutter of UGent admits that it is a liberal law, but that universities still can’t “do whatever we want”. Any planned research must receive approval from both regional and federal ethics committees. “There are strict regulations,” she says. “It has to be relevant, and we must explain why we want to do the work. It is actually time-consuming and difficult to get clearance. Another condition is we must be given informed consent by patients. So we tell them quite specifically what we will do with the embryos – not a vague ‘research’ explanation.”

Access to embryos is the other reason for Flanders’ success in this field of research. “We have a unique situation in that we have a lot of embryos available,” explains De Sutter. “Our busy in vitro fertilisation programme, with 2,500 cycles a year, is the second largest in the country. Only VUB is bigger, with 4,500. This creates the possibility to do this type of research in the first place.”

VUB’s professor Sermon: “The ethical consideration and legal framework in Belgium is one of our assets. This is why we want to stay on the embryo side of the research – it’s really where we have a head-start. This is our niche.”

Genetic diagnosis

The VUB has a strong reputation in the in vitro fertilisation and stem cell community, having made groundbreaking discoveries in the field of male infertility, thanks to intra-cytoplasmic sperm injection of eggs (ICSI), where the best sperm is selected and then injected in the egg in vitro. More recently, VUB has made a name for itself in reproductive genetics. Pre-implantation genetic diagnosis (PGD) alerts couples with known genetic defects or diseases as to whether if the embryo is affected by the problem. One or two cells are taken from the embryo for genetic diagnosis.

The egg is fertilised in vitro, and “if the embryo is healthy, we can place it in the womb,” says Sermon. “At a certain moment, we realised we had all these embryos in a dish with genetic diseases for which there were no models. Now we have a number of hESC lines that carry a disease, which is amazing for research purposes.” One of KUL’s projects is very similar, but working from a different starting point – with iPSC, derived from adult cells. “We are generating disease models – for instance, for cardiac or neural disease – as this can lead to better insight into the disease,” explains professor Verfaillie. “But with PGD, it must be known at conception that there is a potential for the embryo to be sick.

For most diseases, you can’t predict at birth that you will have it; you don’t discover the disease until later in life. We are studying how you can take an adult cell, work backwards and make it into an embryonic cell to generate disease models.”

Thomas O’Leary at UGent, meanwhile, is taking advantage of his embryologist background to create his own research focus that is not being done in many places – human embryonic stem cell origin.

“The core of my work is understanding how the cells of the embryo transform into stem cells,” he explains. “All embryonic stem cells have the same general characteristics, which are related to the changes that happen [in the embryo] when they are created.” The inner cell mass undergoes a series of transformations before the stem cells emerge. “No one has ever really looked at this stage before in detail,” notes O’Leary. “The importance of this new stage, which I’ve called the post inner cell mass intermediate (PICMI), provides insight into why human embryonic stem cells have the characteristics they have and the potential to create pluripotent stem cells with different characteristics.”

The paper, he says, is just “an initial step, a platform in identifying the structure. There is still so much to learn, so much unknown. It’s exciting to contribute to something that has this much potential”.