Infertility

Building embryo-like cells in the lab

/ Kevin McCormack / 1 Comment
Dr. Magdalena Zernicka-Goetz: Photo courtesy Caltech

Human embryonic stem cells (hESCs) have many remarkable properties, not the least of which is their ability to turn into every other kind of cell in our body. But there are limits to what researchers can do with embryonic stem cells. One issue is that there aren’t always hESCs available – they come from eggs donated by couples who have undergone in vitro fertilization. Another is that researchers can only develop these cells in the laboratory for 14 days (though that rule may be changing).

Now researchers at Caltech have developed a kind of hESC-in-a-dish that could help make it easier to answer questions about human development without the need to wait for a new line of hESCs.

The team, led by Magdalena Zernicka-Goetz, used a line of expanded pluripotent cells (EPSCs), originally derived from a human embryo, to create a kind of 3D model that mimics some of the activities of an embryo.

The cool thing about these cells is that, because they were originally derived from an embryo, they retain some “memory” of how they are supposed to work. In a news release Zernicka-Goetz says this enables them to display elements of both polarization and cavitation, early crucial phases in the development of a human embryo.

“The ability to assemble the basic structure of the embryo seems to be a built-in property of these earliest embryonic cells that they are simply unable to ‘forget.’ Nevertheless, either their memory is not absolutely precise or we don’t yet have the best method of helping the cells recover their memories. We still have further work to do before we can get human stem cells to achieve the developmental accuracy that is possible with their equivalent mouse stem cell counterparts.”

Being able to create these embryo-like elements means researchers can generate cells in large numbers and won’t be so dependent on donated embryos.

In the study, published in the journal Nature Communications, the researchers say this could help them develop a deeper understanding of embryonic development.

“Understanding human development is of fundamental biological and clinical importance. Despite its significance, mechanisms behind human embryogenesis remain largely unknown…. this stem cell platform provides insights into the design of stem cell models of embryogenesis.

Building a new mouse, one stem cell at a time

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Science is full of acronyms. There are days where it feels like you need a decoder ring just to understand a simple sentence. A recent study found that between 1950 and 2019 researchers used more than 1.1 million unique acronyms in scientific papers. There’s even an acronym for three letter acronyms. It’s TLAs. Which of course has one more letter than the thing it stands for.

I only mention this because I just learned a new acronym, but this one could help change the way we are able to study causes of infertility. The acronym is IVG or in vitro gametogenesis and it could enable scientists to create both sperm and egg, from stem cells, and grow them in the lab. And now scientists in Japan have done just that and allowed these fertilized eggs to then develop into mice.

The study, published in the journal Science, was led by Dr. Katsuhiko Hayashi of Kyushu University in Japan. Dr. Hayashi is something of a pioneer in the field of IVG. In the past his team were the first to produce both mouse sperm, and mouse eggs from stem cells. But they ran into a big obstacle when they tried to get the eggs to develop to a point where they were ready to be fertilized.

Over the last five years they have worked to find a way around this obstacle and, using mouse embryonic stem cells, they developed a process to help these stem cell-generated eggs mature to the point where they were viable.

In an article in STAT News Richard Anderson, Chair of Clinical Reproductive Science at the University of Edinburgh, said this was a huge achievement: “It’s a very serious piece of work. This group has done a lot of impressive things leading up to this, but this latest paper really completes the in vitro gametogenesis story by doing it in a completely stem-cell-derived way.”

The technique could prove invaluable in helping study infertility in people and, theoretically, could one day lead to women struggling with infertility to be able to use their own stem cells to create eggs or men their own sperm. However, the researchers say that even if that does become possible it’s likely a decade or more away.

While the study is encouraging on a scientific level, it’s raising some concerns on an ethical level. Should there be limits on how many of these manufactured embryos that a couple can create? Can someone create dozens or hundreds of these embryos and then sift through them, using genetic screening tools, to find the ones that have the most desirable traits?

One thing is clear, while the science is evolving, bioethicists, scholars and the public need to be discussing the implications for this work, and what kinds of restraints, if any, need to be applied before it’s RFPT (ready for prime time – OK, I made that one up.)

Charting a course for the future

/ Kevin McCormack / 1 Comment
A new home for stem cell research?

Have you ever been at a party where someone says “hey, I’ve got a good idea” and then before you know it everyone in the room is adding to it with ideas and suggestions of their own and suddenly you find yourself with 27 pages of notes, all of them really great ideas. No, me neither. At least, not until yesterday when we held the first meeting of our Scientific Strategy Advisory Panel.

This is a group that was set up as part of Proposition 14, the ballot initiative that refunded CIRM last November (thanks again everyone who voted for that). The idea was to create a panel of world class scientists and regulatory experts to help guide and advise our Board on how to advance our mission. It’s a pretty impressive group too. You can see who is on the SSAP here.  

The meeting involved some CIRM grantees talking a little about their work but mostly highlighting problems or obstacles they considered key issues for the future of the field as a whole. And that’s where the ideas and suggestions really started flowing hard and fast.

It started out innocently enough with Dr. Amander Clark of UCLA talking about some of the needs for Discovery or basic research. She advocated for a consortium approach (this quickly became a theme for many other experts) with researchers collaborating and sharing data and findings to help move the field along.

She also called for greater diversity in research, including collecting diverse cell samples at the basic research level, so that if a program advanced to later stages the findings would be relevant to a wide cross section of society rather than just a narrow group.

Dr. Clark also said that as well as supporting research into neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, there needed to be a greater emphasis on neurological conditions such as autism, bipolar disorder and other mental health problems.

(CIRM is already committed to both increasing diversity at all levels of research and expanding mental health research so this was welcome confirmation we are on the right track).

Dr. Mike McCun called for CIRM to take a leadership role in funding fetal tissue research, things the federal government can’t or won’t support, saying this could really help in developing an understanding of prenatal diseases.

Dr. Christine Mummery, President of ISSCR, advocated for support for early embryo research to deepen our understanding of early human development and also help with issues of infertility.

Then the ideas started coming really fast:

  • There’s a need for knowledge networks to share information in real-time not months later after results are published.
  • We need standardization across the field to make it easier to compare study results.
  • We need automation to reduce inconsistency in things like feeding and growing cells, manufacturing cells etc.
  • Equitable access to CRISPR gene-editing treatments, particularly for underserved communities and for rare diseases where big pharmaceutical companies are less likely to invest the money needed to develop a treatment.
  • Do a better job of developing combination therapies – involving stem cells and more traditional medications.

One idea that seemed to generate a lot of enthusiasm – perhaps as much due to the name that Patrik Brundin of the Van Andel Institute gave it – was the creation of a CIRM Hotel California, a place where researchers could go to learn new techniques, to share ideas, to collaborate and maybe take a nice cold drink by the pool (OK, I just made that last bit up to see if you were paying attention).

The meeting was remarkable not just for the flood of ideas, but also for its sense of collegiality.  Peter Marks, the director of the Food and Drug Administration’s Center for Biologics Evaluation and Research (FDA-CBER) captured that sense perfectly when he said the point of everyone working together, collaborating, sharing information and data, is to get these projects over the finish line. The more we work together, the more we will succeed.

Perseverance: from theory to therapy. Our story over the last year – and a half

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Some of the stars of our Annual Report

It’s been a long time coming. Eighteen months to be precise. Which is a peculiarly long time for an Annual Report. The world is certainly a very different place today than when we started, and yet our core mission hasn’t changed at all, except to spring into action to make our own contribution to fighting the coronavirus.

This latest CIRM Annual Reportcovers 2019 through June 30, 2020. Why? Well, as you probably know we are running out of money and could be funding our last new awards by the end of this year. So, we wanted to produce as complete a picture of our achievements as we could – keeping in mind that we might not be around to produce a report next year.

Dr. Catriona Jamieson, UC San Diego physician and researcher

It’s a pretty jam-packed report. It covers everything from the 14 new clinical trials we have funded this year, including three specifically focused on COVID-19. It looks at the extraordinary researchers that we fund and the progress they have made, and the billions of additional dollars our funding has helped leverage for California. But at the heart of it, and at the heart of everything we do, are the patients. They’re the reason we are here. They are the reason we do what we do.

Byron Jenkins, former Naval fighter pilot who battled back from his own fight with multiple myeloma

There are stories of people like Byron Jenkins who almost died from multiple myeloma but is now back leading a full, active life with his family thanks to a CIRM-funded therapy with Poseida. There is Jordan Janz, a young man who once depended on taking 56 pills a day to keep his rare disease, cystinosis, under control but is now hoping a stem cell therapy developed by Dr. Stephanie Cherqui and her team at UC San Diego will make that something of the past.

Jordan Janz and Dr. Stephanie Cherqui

These individuals are remarkable on so many levels, not the least because they were willing to be among the first people ever to try these therapies. They are pioneers in every sense of the word.

Sneha Santosh, former CIRM Bridges student and now a researcher with Novo Nordisk

There is a lot of information in the report, charting the work we have done over the last 18 months. But it’s also a celebration of everyone who made it possible, and our way of saying thank you to the people of California who gave us this incredible honor and opportunity to do this work.

We hope you enjoy it.

Lab-grown human sperm cells could unlock treatments for infertility

/ Kevin McCormack / 1 Comment
Dr. Miles Wilkinson: Photo courtesy UCSD

Out of 100 couples in the US, around 12 or 13 will have trouble starting a family. In one third of those cases the problem is male infertility (one third is female infertility and the other third is a combination of factors). In the past treatment options for men were often limited. Now a new study out of the University of California San Diego (UCSD) could help lead to treatments to help these previously infertile men have children of their own.

The study, led by Dr. Miles Wilkinson of UCSD School of Medicine, targeted spermatogonial stem cells (SSCs), which are the cells that develop into sperm. In the past it was hard to isolate these SSCs from other cells in the testes. However, using a process called single cell RNA sequencing – which is like taking a photo of all the gene expression happening in one cell at a precise moment – the team were able to identify the SSCs.

In a news release Dr. Wilkinson, the senior author of the study, says this is a big advance on previous methods: “We think our approach — which is backed up by several techniques, including single-cell RNA-sequencing analysis — is a significant step toward bringing SSC therapy into the clinic.”

Identifying the SSCs was just the first step. Next the team wanted to find a way to be able to take those cells and grow and multiply them in the lab, an important step in having enough cells to be able to treat infertility.

So, they tested the cells in the lab and identified something called the AKT pathway, which controls cell division and survival. By blocking the AKT pathway they were able to keep the SSCs alive and growing for a month. Next they hope to build on the knowledge and expand the cells for even longer so they could be used in a clinical setting.

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Illustrations by Vishaala Wilkinson

The hope is that this could ultimately lead to treatments for men whose bodies don’t produce sperm cells, or enough sperms cells to make them fertile. It could also help children going through cancer therapy which can destroy their ability to have children of their own later in life. By taking sperm cells and freezing them, they could later be grown and expanded in the lab and injected back into the testes to restore sperm production.

The study is published in the journal Proceedings of the National Academy of Science.

Stories that caught our eye: SanBio’s Traumatic Brain Injury trial hits its target; A new approach to endometriosis; and a SCID kid celebrates Halloween in style

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Traumatic brain injury: graphic courtesy Brainline.org

Hopeful signs for treating brain injuries

There are more than 200,000 cases of traumatic brain injury (TBI) in the US every year. The injuries can be devastating, resulting in everything from difficult sleeping to memory loss, depression and severe disability. There is no cure. But this week the SanBio Group had some encouraging news from its Phase 2 STEMTRA clinical trial.

In the trial patients with TBI were given stem cells, derived from the bone marrow of healthy adult donors. When transplanted into the area of injury in the brain, these cells appear to promote recovery by stimulating the brain’s own regenerative ability.

In this trial the cells demonstrated what the company describes as “a statistically significant improvement in their motor function compared to the control group.”

CIRM did not fund this research but we are partnering with SanBio on another clinical trial targeting stroke.

 

Using a woman’s own cells to heal endometriosis

Endometriosis is an often painful condition that is caused when the cells that normally line the inside of the uterus grow outside of it, causing scarring and damaging other tissues. Over time it can result in severe pain, infertility and increase a woman’s risk for ovarian cancer.

There is no effective long-term treatment but now researchers at Northwestern Medicine have developed an approach, using the woman’s own cells, that could help treat the problem.

The researchers took cells from women, turned them into iPS pluripotent stem cells and then converted those into healthy uterine cells. In laboratory tests these cells responded to the progesterone, the hormone that plays a critical role in the uterus.

In a news release, Dr. Serdar Bulun, a senior author of the study, says this opens the way to testing these cells in women:

“This is huge. We’ve opened the door to treating endometriosis. These women with endometriosis start suffering from the disease at a very early age, so we end up seeing young high school girls getting addicted to opioids, which totally destroys their academic potential and social lives.”

The study is published in the journal Stem Cell Reports.

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Happy Halloween from a scary SCID kid

A lot of the research we write about on the Stem Cellar focuses on potential treatments or new approaches that show promise. So every once in a while, it’s good to remind ourselves that there are already stem cell treatments that are not just showing promise, they are saving lives.

That is the case with Ja’Ceon Golden. Regular readers of our blog know that Ja’Ceon was diagnosed with Severe Combined Immunodeficiency (SCID) also known as “bubble baby disease” when he was just a few months old. Children born with SCID often die in the first few years of life because they don’t have a functioning immune system and so even a simple infection can prove life-threatening.

Fortunately Ja’Ceon was enrolled in a CIRM-funded clinical trial at UC San Francisco where his own blood stem cells were genetically modified to correct the problem.

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Today he is a healthy, happy, thriving young boy. These pictures, taken by his great aunt Dannie Hawkins, including one of him in his Halloween costume, show how quickly he is growing. And all thanks to some amazing researchers, an aunt who wouldn’t give up on him, and the support of CIRM.

Stem Cell Roundup: Artificial Embryos to Study Miscarriage and ALS Insight – Muscle Repair Cells Go Rogue

/ Todd Dubnicoff / 2 Comments

Stem Cell Image of the Week: Artificial embryos for studying miscarriage (Adonica Shaw)

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Mouse embryos artificially generated by combining three types of stem cells.
Image: University of Cambridge.

This week’s stem cell image of the week comes from a team of researchers from The University of Cambridge who published research in Nature Cell Biology earlier this week indicating they’d achieved a breakthrough in stem cell research that resulted in the generation of a key developmental step that’d never before been achieved when trying to generate an artificial embryo.

To create the artificial embryo, the scientists combined mouse embryonic stem cells with two other types of stem cells that are present in the very earliest stages of embryo development. The reseachers grew the three stem cell types into a dish and coaxed them into simulating a process called gastrulation – one of the very first events that happens during a creature’s development in which the early embryo begins reorganizing into more and more complex multilayer organ structures.

In an interview with The Next Web (TNW), Professor Magdalena Zernicka-Goetz, who led the research team, says:

”Our artificial embryos underwent the most important event in life in the culture dish. They are now extremely close to real embryos. To develop further, they would have to implant into the body of the mother or an artificial placenta.”

The goal of this research isn’t to create mice on demand. Its purpose is to gain insights into early life development. And that could lead to a giant leap in our understanding of what happens during the period in a woman’s pregnancy where the risk of miscarriage is highest.

According to professor Zernicka-Goetz,

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Magdalena Zernicka-Goetz, PhD

“We can also now try to apply this to the equivalent human stem cell types and so study the very earliest events in human embryo development without actually having to use natural human embryos.The early stages of embryo development are when a large proportion of pregnancies are lost and yet it is a stage that we know very little about. Now we have a way of simulating embryonic development in the culture dish, so it should be possible to understand exactly what is going on during this remarkable period in an embryo’s life, and why sometimes this process fails.”

Muscle repair cells go rogue – a possible drug target for ALS?
Call it a case of a good cell gone bad. This week researchers at Sanford Burnham Prebys Medical Discovery Institute, report in Nature Cell Biology that fibro-adipogenic progenitors (FAPs) – cells that are critical in coordinating the repair of torn muscles – can turn rogue, causing muscles to wither and scar. This “Dr. Jekyl and Mr. Hype” discovery may lead to novel treatments for a number of incurable disorders like amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and spinal cord injury.

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Senior author Pier Lorenzo Puri, M.D. (right) and co-first author Luca Madaro, Ph.D. Credit: Fondazione Santa Lucia IRCCS

When muscle is strained, whether due to an acute injury or even weight-lighting, a consistent order of events occurs within the muscle. FAB cells enter the muscle tissue after immune cells called macrophages come in and gobble up dead tissue but before muscle stem cells are stimulated to regenerate the lost muscle. However, to the researchers’ surprise, something entirely different happens in the case of neuromuscular disorders like ALS where nerve signal connections to the muscles degenerate.

Once nerves are no longer attached to muscle and stop sending movement signals from the brain, the macrophages don’t infiltrate the muscle and instead the FAPs pile up in the muscle and never leave. And as a result, muscle stem cells are never activated. In ALS patients, this cellular train crash leads to progressive loss of muscle control to move the limbs and ultimately even to breathe.

The promising news from these findings, which were funded in part by CIRM, is that the team identified of an out-of-whack cell signaling pathway that is responsible for the breakdown in the rogue function of the FAP cells. The researchers hope further studies of this pathway’s role in muscle degeneration may lead to novel therapies and disease-screening technologies for ALS and other motor neuron diseases.

Stem cell roundup: summer scientists, fat-blocking cells & recent human evolution

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Stem cell photo of the week: high schooler becoming a stem cell pro this summer

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High school student Anna Guzman learning important lab skills at UC Davis

This summer’s CIRM SPARK Programs, stem cell research internships for high school students, are in full swing. Along with research assignments in top-notch stem cell labs, we’ve asked the students to chronicle their internship experiences through Instagram. And today’s stem cell photo of the week is one of those student-submitted posts. The smiling intern in this photo set is Anna Guzman, a rising junior from Sheldon High School who is in the UC Davis SPARK Program. In her post, she describes the lab procedure she is doing:

“The last step in our process to harvest stem cells from a sample of umbilical cord blood! We used a magnet to isolate the CD34 marked stem cells [blood stem cells] from the rest of the solution.”

Only a few days in and Anna already looks like a pro! It’s important lab skills like this one that could land Anna a future job in the stem cell field. Check out #cirmsparklab on Instagram to view the ever-growing number of posts.

Swiss team identifies a cell type that block formation of fat cells

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(Left) Mature human fat cells grown in a Petri dish (green, lipid droplets). (Right) A section of mouse fat tissue showing, in the middle, a blood vessel (red circle) surrounded by fat cell blocking cells called Aregs (arrows). [Bart Deplancke/EPFL]

Liposuction surgery helps slim and reshape areas of a person’s body through the removal of excess fat tissue. While the patient is certainly happy to get rid of those extra pounds, that waste product is sought after by researchers because it’s a rich source of regenerative cells including fat stem cells.

The exact populations of cells in this liposuction tissue has been unclear, so a collaboration of Swiss researchers – at Ecole Polytechnique Fédérale de Lausanne (EPFL) and Eidgenössische Technische Hochschule Zürich (ETHZ) – used a cutting-edge technique allowing them to examine the gene activity within single cells.

The analysis was successful in identifying several newly defined subpopulations of cells in the fat tissue. To their surprise, one of those cell types did not specialize into fat cells but instead did the opposite: they inhibited other fat stem cells from giving rise to fat cells. The initial experiments were carried out in mice, but the team went on to show similar fat-blocking cells in human tissue. Further experiments will explore the tantalizing prospect of applying these cells to control obesity and the many diseases, like diabetes, that result from it.

The study was published June 20st in Nature.

Connection identified between recent human evolution & risk for premature birth
Evidence of recent evolution in a human gene that’s critical for maintaining pregnancy may help explain why some populations have a higher risk for giving birth prematurely than others. That’s according to a recent report by researchers at the University of Stanford School of Medicine.

The study, funded in part by CIRM’s Genomics Initiative, compared DNA from people with East Asian, European and African ancestry. They specifically examined the gene encoding the progesterone hormone receptor which helps keep a pregnant woman from going into labor too soon. The gene is also associated with preterm births, the leading cause of infant death in the U.S.

The team was very surprise to find that people with East Asian ancestry had an evolutionarily new version of the gene while the European and African populations had mixtures of new and ancient versions. These differences may explain why the risk for premature birth among East Asian populations is lower than among pregnant women of European and African descent, though environment clearly plays a role as well.

Pediatrics professor Gary Shaw, PhD, one of the team leaders, put the results in perspective:

“Preterm birth has probably been with us since the origin of the human species,” said Shaw in a press release, “and being able to track its evolutionary history in a way that sheds new light on current discoveries about prematurity is really exciting.”

The study was published June 21st in The American Journal of Human Genetics.

Stem Cell Roundup: New infertility tools, helping the 3 blind mice hear and cow ESCs

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Cool Stem Cell Image of the Week

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Human egg grown from immature cells in ovarian tissue. (credit: David Albertini)

This week’s Cool Stem Cell Image of the Week comes to us from the lab of reproductive biologist Evelyn Telfer at the University of Edinburgh. Telfer and her team successfully grew human eggs cells from immature ovarian tissue.

This technology could revolutionize the way doctors approach infertility. For instance, when girls and young women undergo chemotherapy for cancer, their eggs are often damaged. By preserving a small piece of ovarian tissue before the cancer treatments, this method could be used to generate eggs later in life for in vitro fertilization. Much more work is necessary to figure out if these eggs are healthy and safe to use to help infertile women.

The study was recently published in Molecular Human Reproduction and was picked up this Science writer Kelly Servick.

Forget 3 blind mice, iPS cells could help 3 deaf mice hear again (Kevin McCormack)
For years scientists have been trying to use stem cells to restore hearing to people who are deaf or hearing impaired. Now a group of researchers in Japan may have found a way.

The team used human iPS cells to create inner ear cells, the kind damaged in one of the most common forms of hereditary deafness. They then transplanted them into the inner ears of mice developing in the womb that are suffering from a congenital form of hearing loss. The cells appeared to engraft and produce a protein, Connexin 30, known to be critical in hearing development.

The research, published in the journal Scientific Reports, could be an important step towards developing a therapy for congenital hearing loss in people.

UC Davis team isolates cow embryonic stem cells for the first time

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An early stage cow embryo. Inner cell mass (red) is source of embryonic stem cells. (Credit: Pablo Ross/UC Davis) 

Although human embryonic stem cells (ESCs) were isolated way back in ’98, researchers haven’t had similar luck with embryonic stem cells from cows. Until this week, that is.  A UC Davis team just published a report in PNAS showing that they not only can isolate cow ESCs but their method works almost 100% of the time.

 

Genetic engineering of these cow stem cells could have huge implications for the cattle industry. Senior author Pablo Ross mentioned in a press release how this breakthrough could help speed up the process of generating superior cows that produce more milk, release less methane and are more resistant to disease:

“In two and a half years, you could have a cow that would have taken you about 25 years to achieve. It will be like the cow of the future. It’s why we’re so excited about this.”

These cow ESCs may also lead to better models of human disease. Because of their small size, rat and mouse models are not always a good representation of how potential therapies or drugs will affect humans. Creating stem cell models from larger animals may provide a better representation.

Knocking out sexually transmitted disease with stem cells and CRISPR gene editing

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When used in tandem, stem cells and gene editing make a powerful pair in the development of cell therapies for genetic diseases like sickle cell anemia and bubble baby disease. But the applications of these cutting-edge technologies go well beyond cell therapies.

This week, researchers at the Wellcome Trust Sanger Institute in the UK and the University of British Columbia (UBC) in Canada, report their use of induced pluripotent stem cells (iPSCs) and the CRISPR gene editing to better understand chlamydia, a very common sexually transmitted disease. And in the process, the researchers gained insights for developing new drug treatments.

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Human macrophage, a type of white blood cell, interacting with a Chlamydia trachomatis bacteria cell. Image: Sanger Institute / Genome Research Limited

Chlamydia is caused by infection with the bacteria Chlamydia trachomatis. According to the Centers for Disease Control (CDC), there were over 1.5 million cases of Chlamydia reported in the U.S. in 2015. And there are thought to be almost 3 million new cases each year. Men with Chlamydia usually do not face many health issues. Women, on the other hand, can suffer serious health complications like pelvic inflammatory disease and infertility.

Although it’s easily treatable with antibiotics, the disease often goes unnoticed because infected people may not show symptoms. And because of the rising fear of antibiotic-resistant bacteria, there’s a need to develop new types of drugs to treat Chlamydia.

To tackle this challenge, the research teams focused first on better understanding how the bacteria infects the human immune system. As first author Dr. Amy Yeung from the Wellcome Trust Sanger Institute explained in a press release, researchers knew they were up against difficult to treat foe:

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Amy Yeung

“Chlamydia is tricky to study because it can permeate and hide in macrophages [a type of white blood cell] where it is difficult to reach with antibiotics. Inside the macrophage, one or two chlamydia cells can replicate into hundreds in just a day or two, before bursting out to spread the infection.”

In the study, published in Nature Communications, the teams chose to examine human macrophages derived from iPSCs. This decision had a few advantages over previous studies.  Most Chlamydia studies up until this point had either used macrophages from mice, which don’t always accurately reflect what’s going on in the human immune system, or human macrophage cell lines, which have genetic abnormalities that allow them to divide indefinitely.

With these human iPSC-derived macrophages, the team then used CRISPR gene editing technology to systematically delete, or “knockout”, genes that may play a role in Chlamydia infection. Lead author Dr. Robert Hancock from UBC described the power of this approach:

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Robert Hancock

“We can knock out specific genes in stem cells and look at how the gene editing influences the resulting macrophages and their interaction with chlamydia. We’re effectively sieving through the genome to find key players and can now easily see genes that weren’t previously thought to be involved in fighting the infection.”

In fact, they found two genes that appear to play an important role in Chlamydia infection. When they knocked out either the IRF5 or IL-10RA gene, the macrophages were much more vulnerable to infection. The team is now eager to examine these two genes as possible targets for novel Chlamyia drug treatments. But as Dr. Gordon Dougan –the senior author from the Sanger Institute – explains, these studies could be far-reaching:

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Gordon Dougan

“This system can be extended to study other pathogens and advance our understanding of the interactions between human hosts and infections. We are starting to unravel the role our genetics play in battling infections, such as chlamydia, and these results could go towards designing more effective treatments in the future.”