Benjamin Freedman, PhD speaks about CRISPR and the future of treating polycystic kidney disease in recent study: "Organoid cystogenesis reveals a critical role of microenvironment in human PKD"

By ASN Staff

A recent study was published online in Nature Materials entitled “Organoid cystogenesis reveals a critical role of microenvironment in human polycystic kidney disease” on October 2, 2017.

Please access the abstract and full report on the Nature website.

 

To get a behind-the-scenes look into the recent study, Kidney News Online asked Dr. Freedman, senior author and Assistant Professor of Medicine at the University of Washington School of Medicine, Division of Nephrology, to answer several questions about the findings and what they mean for the future.

1. How would you briefly describe the findings of this study?

Polycystic kidney disease (PKD) is one of the most common genetic disorders, affecting one in every ~600 people on the planet, and passed from parent to child. The hallmark of PKD is the formation of large cysts from tubules in the kidneys and other organs. The two genes that commonly cause PKD have been known for over twenty years. To develop therapies, we need to understand how mutations in these genes cause PKD – and after twenty years, we still don’t know the answer.

CRISPR is a new technology that lets us edit gene sequences, like cutting and pasting in a word processor. We used CRISPR to create human stem cells with mutations in the PKD genes. We then grew these stem cells into mini-kidney organoids – tiny clusters of tubules that resemble primitive kidneys. PKD mini-kidneys formed cysts, whereas control mini-kidneys without PKD mutations didn’t form cysts.

Using this ‘PKD in a dish’ system, we have made a breakthrough in understanding cysts form. We observed that before the cysts formed, the mini-kidney tubules were peeling off of the petri dish. When we manually detached the mini-kidneys from the dish, they formed cysts at a much higher rate. We didn’t need to look through a microscope to see these structures – the cysts grew large enough to see with the naked eye. The PKD organoids also had trouble interacting with collagen gels. We linked these problems to a PKD gene that encodes a ‘receptor’ sticking out of the cell, like a tiny hand looking to grab onto something.
 

2. What do you believe is the importance of the findings?

petri3 - Copy.jpg

All of our findings are pointing in the direction that the problem with PKD cyst formation is a problem of cell adhesion (stickiness). The PKD genes seem to be helping the whole tubule to stick together and avoid unraveling like a rubber band. This gives us an important clue in terms of how PKD might actually work in people, and which agents might be helpful in preventing it. From a gene therapy perspective, it is striking that simply changing one gene can make the difference between a tightly coiled tubule, and a giant ballooning cyst.
 

3. And for which groups does it matter? Kidney disease patients, the general public, physicians?

Our findings, together with important research by other groups in complementary systems, are helping to refocus the PKD research field on how PKD mutations affects the cell’s interaction with its surroundings. For doctors and patients, this gives hope that there may be things we can introduce into the surrounding environment of the kidneys that could prevent PKD. In general, our study demonstrates that progress is being made in understanding how PKD actually works at the molecular level, and in our ability to gene-edit PKD genes to dramatically affect cystogenesis. The ‘disease in a dish’ models that we have established using CRISPR are enabling us to make rapid progress in this area.
 

4. What effect do you think your team’s proof of these findings will have on the future of treating patients?

What we are doing now is using the information we have gleaned from this study as a starting point for therapy discovery. We are looking both at ways that gene editing could be used to prevent PKD, as well as pathways that we could intervene with pharmacologically to stop cyst formation in its tracks. Our early studies are encouraging and I am hopeful that we can soon translate these discoveries into safe, efficacious, and cost-effective therapies for this devastating disease.
 

5. What effect do you see CRISPR having in your and your colleague’s future research?

benjamin-freedman-1-e1478106780667 - Copy.jpg

CRISPR is a significant advance. When technologies like CRISPR come out, that achieve a certain level of technical success, they typically stay around for a long time. As amazing as CRISPR is, however, it is only a tool. Using CRISPR to actually cure disease – that’s the real payload, that’s where we will continue to put our efforts, and hopefully the field will continue to move in that direction as well. Used appropriately, CRISPR can teach us what individual genes actually do – which, as PKD illustrates, is a bottleneck for therapy development. As we understand the genome better, we will be able to come up with ways to perform gene editing in human patients, to treat genetic kidney disease. 

If you have any further questions on this study or the broader topic, please contact Kidney News Online at info@kidneynews.org.

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A recent study was published online in Nature Materials entitled “Organoid cystogenesis reveals a critical role of microenvironment in human polycystic kidney disease” on October 2, 2017.

Please access the abstract and full report on the Nature website.

 

To get a behind-the-scenes look into the recent study, Kidney News Online asked Dr. Freedman, senior author and Assistant Professor of Medicine at the University of Washington School of Medicine, Division of Nephrology, to answer several questions about the findings and what they mean for the future.

1. How would you briefly describe the findings of this study?

Polycystic kidney disease (PKD) is one of the most common genetic disorders, affecting one in every ~600 people on the planet, and passed from parent to child. The hallmark of PKD is the formation of large cysts from tubules in the kidneys and other organs. The two genes that commonly cause PKD have been known for over twenty years. To develop therapies, we need to understand how mutations in these genes cause PKD – and after twenty years, we still don’t know the answer.

CRISPR is a new technology that lets us edit gene sequences, like cutting and pasting in a word processor. We used CRISPR to create human stem cells with mutations in the PKD genes. We then grew these stem cells into mini-kidney organoids – tiny clusters of tubules that resemble primitive kidneys. PKD mini-kidneys formed cysts, whereas control mini-kidneys without PKD mutations didn’t form cysts.

Using this ‘PKD in a dish’ system, we have made a breakthrough in understanding cysts form. We observed that before the cysts formed, the mini-kidney tubules were peeling off of the petri dish. When we manually detached the mini-kidneys from the dish, they formed cysts at a much higher rate. We didn’t need to look through a microscope to see these structures – the cysts grew large enough to see with the naked eye. The PKD organoids also had trouble interacting with collagen gels. We linked these problems to a PKD gene that encodes a ‘receptor’ sticking out of the cell, like a tiny hand looking to grab onto something.
 

2. What do you believe is the importance of the findings?

petri3 - Copy.jpg

All of our findings are pointing in the direction that the problem with PKD cyst formation is a problem of cell adhesion (stickiness). The PKD genes seem to be helping the whole tubule to stick together and avoid unraveling like a rubber band. This gives us an important clue in terms of how PKD might actually work in people, and which agents might be helpful in preventing it. From a gene therapy perspective, it is striking that simply changing one gene can make the difference between a tightly coiled tubule, and a giant ballooning cyst.
 

3. And for which groups does it matter? Kidney disease patients, the general public, physicians?

Our findings, together with important research by other groups in complementary systems, are helping to refocus the PKD research field on how PKD mutations affects the cell’s interaction with its surroundings. For doctors and patients, this gives hope that there may be things we can introduce into the surrounding environment of the kidneys that could prevent PKD. In general, our study demonstrates that progress is being made in understanding how PKD actually works at the molecular level, and in our ability to gene-edit PKD genes to dramatically affect cystogenesis. The ‘disease in a dish’ models that we have established using CRISPR are enabling us to make rapid progress in this area.
 

4. What effect do you think your team’s proof of these findings will have on the future of treating patients?

What we are doing now is using the information we have gleaned from this study as a starting point for therapy discovery. We are looking both at ways that gene editing could be used to prevent PKD, as well as pathways that we could intervene with pharmacologically to stop cyst formation in its tracks. Our early studies are encouraging and I am hopeful that we can soon translate these discoveries into safe, efficacious, and cost-effective therapies for this devastating disease.
 

5. What effect do you see CRISPR having in your and your colleague’s future research?

benjamin-freedman-1-e1478106780667 - Copy.jpg

CRISPR is a significant advance. When technologies like CRISPR come out, that achieve a certain level of technical success, they typically stay around for a long time. As amazing as CRISPR is, however, it is only a tool. Using CRISPR to actually cure disease – that’s the real payload, that’s where we will continue to put our efforts, and hopefully the field will continue to move in that direction as well. Used appropriately, CRISPR can teach us what individual genes actually do – which, as PKD illustrates, is a bottleneck for therapy development. As we understand the genome better, we will be able to come up with ways to perform gene editing in human patients, to treat genetic kidney disease. 

If you have any further questions on this study or the broader topic, please contact Kidney News Online at info@kidneynews.org.

Date:
Tuesday, October 24, 2017