New findings about muscle stem cells reveals the potential for growing replacement organs

Chrissa Kioussi’s group at Oregon State University has made exciting advances in further unraveling the scientific mysteries of stem cells. In work detailed in Scientific Reports, this group found that muscle-specific stem cells actually have the ability to make multiple different cell types.

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Pumping up our knowledge about muscle stem cells

Initially, this group was interested in understanding how gene expression changes during embryonic development of skeletal muscle. To understand this process, they labeled muscle stem cells with a kind of fluorescent dye, called GFP, which allowed them to isolate these cells at different stages of development.  Once isolated, they determined what genes were being expressed by RNA sequencing. Surprisingly, they found that in addition to genes involved in muscle formation, they also identified activation of genes involved in the blood, nervous, immune and skeletal systems.

This work is particularly exciting, because it suggests the existence of stem cell “pockets,” or stem cells that are capable of not only making a specific cell type, but an entire organ system.

In a press release, Dr. Kioussi said:

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Chrissa Kioussi, PhD

“That cell populations can give rise to so many different cell types, we can use it at the development stage and allow it to become something else over time… We can identify these cells and be able to generate not one but four different organs from them — this is a prelude to making body parts in a lab.” 

This study is particularly exciting because it gives more credence to the idea that entire limbs can be reconstructed from a small group of stem cells. Such advances could have enormous meaning for individuals who have lost body parts due to amputation or disease.

Stem Cell Roundup: Protein shows promise in treating deadliest form of breast cancer: mosquito spit primes our body for disease

Triple negative breast cancerTriple negative breast cancer is more aggressive and difficult to treat than other forms of the disease and, as a result, is more likely to spread throughout the body and to recur after treatment. Now a team at the University of Southern California have identified a protein that could help change that.

The research, published in the journal Nature Communications, showed that a protein called TAK1 allows cancer cells from the tumor to migrate to the lungs and then form new tumors which can spread throughout the body. There is already an FDA-approved drug called OXO that has been shown to block TAK1, but this does not survive in the blood so it’s hard to deliver to the lungs.

The USC team found a way of using nanoparticles, essentially a tiny delivery system, to take OXO and carry it to the lungs to attack the cancer cells and stop them spreading.

triple_negative_breast_cancer_particle_graphic-768x651In a news release Min Yu, the principal investigator on the team, said that although this has only been tested in mice the results are encouraging:

“For patients with triple-negative breast cancer, systemic chemotherapies are largely ineffective and highly toxic. So, nanoparticles are a promising approach for delivering more targeted treatments, such as OXO, to stop the deadly process of metastasis.”

Mosquito spit and your immune system

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Mosquito bite: Photo courtesy National Academy of Sciences

Anyone who has ever been bitten by a mosquito knows that it can be itchy and irritable for hours afterwards. But now scientists say the impact of that bite can last for much longer, days in fact, and even help prime your body for disease.

The scientists say that every time a mosquito bites you they inject saliva into the bite to keep the blood flowing freely. But that saliva also has an impact on your immune system, leaving it more vulnerable to diseases like malaria.

OK, so that’s fascinating, and really quite disgusting, but what does it have to do with stem cells? Well, researchers at the National Institute of Health’s (NIH) Malaria and Vector Research Laboratory in Phnom Penh, Cambodia engrafted human stem cells into mice to study the problem.

They found that mice with the human stem cells developed more severe symptoms of dengue fever if they were bitten by a mosquito than if they were just injected with dengue fever.

In an article in Popular Science Jessica Manning, an infectious disease expert at the NIH, said previously we had no idea that mosquito spit had such a big impact on us:

“The virus present in that mosquito’s saliva, it’s like a Trojan horse. Your body is distracted by the saliva [and] having an allergic reaction when really it should be having an antiviral reaction and fighting against the virus. Your body is unwittingly helping the virus establish infection because your immune system is sending in new waves of cells that this virus is able to infect.”

The good news is that if we can develop a vaccine against the saliva we may be able to protect people against malaria, dengue fever, Zika and other mosquito-borne diseases.

A scalable, clinic-friendly recipe for converting skin cells to muscle cells

Way back in 1987, about two decades before Shinya Yamanaka would go on to identify four proteins that can reprogram skin cells into induced pluripotent stem cells (iPSCs), Harold Weintraub’s lab identified the first “master control” protein, MyoD, which can directly convert a skin cell into a muscle cell. Though MyoD opened up new approaches for teasing out the molecular mechanisms of a cell’s identity, it did not produce therapeutic paths for replacing muscle damaged by disease and injury.

That’s because MyoD-generated muscle cells are not amenable to a clinical setting. For a cell therapy to be viable, you need to manufacture large amounts of your product to treat many people. But these MyoD cells do not grow well enough to be effective to serve as a cell replacement therapy. Generating iPSC-derived muscle cells provides the potential of overcoming this limitation but the capacity of the embryonic stem cell-like iPSC for unlimited growth carries a risk of forming tumors after the transplanting iPSC-derived cell therapies into the muscle.

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This image shows iMPCs stained for markers of muscle stem, progenitor and differentiated cells. iMPCs recapitulate muscle differentiation in a dish. Credit: Ori Bar-Nur and Mattia Gerli

A recent study in Stem Cell Reports, by Konrad Hochedlinger’s lab at Massachusetts General Hospital and the Harvard Stem Cell Institute, may provide a work around. The team came up with a recipe that calls for the temporary activation of MyoD in mouse skin cells, along with the addition of three molecules that boost cell reprogramming. The result? Cells they dubbed induced myogenic progenitor cells, or iMPCs, that can make self-sustaining copies of themselves and can be scaled up for manufacturing purposes. On top of that, they show that these iMPCs carry the hallmarks of muscle stem cells and generate muscle fibers when transplanted into mice with leg injuries without signs of tumor formation.

A lot of work still remains to be done, like confirming that these iMPCs truly have the same characteristics as muscle stem cells. But if everything pans out, the potential applications for people suffering from various muscle disorders and injuries is very exciting, as co-first author Mattia FM Gerli, PhD points out in a press release:

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Mattia FM Gerli, PhD

“Patient-specific iMPCs could be used for personalized medicine by treating patients with their own genetically matched cells. If disease-causing mutations are known, as is the case in many muscular dystrophies, one could in principle repair the mutation in iMPCs prior to transplantation of the corrected cells back into the patient.”

Using biological “codes” to generate neurons in a dish

BrainWavesInvestigators at the Scripps Research Institute are making brain waves in the field of neuroscience. Until now, neuroscience research has largely relied on a variety of animal models to understand the complexities of various brain or neuronal diseases. While beneficial for many reasons, animal models do not always allow scientists to understand the precise mechanism of neuronal dysfunction, and studies done in animals can often be difficult to translate to humans. The work done by Kristin Baldwin’s group, however, is revolutionizing this field by trying to re-create this complexity in a dish.

One of the primary hurdles that scientists have had to overcome in studying neuronal diseases, is the impressive diversity of neuronal cell types that exist. The exact number of neuronal subtypes is unknown, but scientists estimate the number to be in the hundreds.

While neurons have many similarities, such as the ability to receive and send information via chemical cues, they are also distinctly specialized. For example, some neurons are involved in sensing the external environment, whereas others may be involved in helping our muscles move. Effective medical treatment for neuronal diseases is contingent on scientists being able to understand how and why specific neuronal subtypes do not function properly.

In a study in the journal Nature, partially funded by CIRM, the scientists used pairs of transcription factors (proteins that affect gene expression and cell identity), to turn skin stem cells into neurons. These cells both physically looked like neurons and exhibited characteristic neuronal properties, such as action potential generation (the ability to conduct electrical impulses). Surprisingly, the team also found that they were able to generate neurons that had unique and specialized features based on the transcription factors pairs used.

The ability to create neuronal diversity using this method indicates that this protocol could be used to recapitulate neuronal diversity outside of the body. In a press release, Dr. Baldwin states:

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Kristin Baldwin, PhD

“Now we can be better genome detectives. Building up a database of these codes [transcription factors] and the types of neurons they produce can help us directly link genomic studies of human brain disease to a molecular understanding of what goes wrong with neurons, which is the key to finding and targeting treatments.”

These findings provide an exciting and promising tool to more effectively study the complexities of neuronal disease. The investigators of this study have made their results available on a free platform called BioGPS in the hopes that multiple labs will delve into the wealth of information they have opened up. Hopefully, this system will lead to more rapid drug discovery for disease like autism and Alzheimer’s

‘Ask The Expert’ on Facebook Live about the power of stem cells to reverse damage caused by a stroke.

facebook-live-brand-awarenessIt’s not often you get a chance to ask a world class stem cell expert a question about their work, and how it might help you or someone you love. But on Thursday, May 31 you can do just that.

CIRM is hosting a special ‘Ask the Expert’ event on Facebook Live. The topic is Strokes and Stem Cells. Just head over to our Facebook Page on May 31st from noon till 1pm PST to experience it live. You can also re-watch the event any time after the broadcast has ended from our Facebook videos page.

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We will be joined by Dr. Gary Steinberg, chair of neurosurgery at Stanford University, who will talk to us about his work in helping reverse the damage caused by a stroke, even for people who experienced a brain attack several years ago.

CIRM Senior Science Officer, Dr. Lila Collins, will talk about other stem cell research targeting stroke, its promise and some of the problems that still need to be overcome.

You will have a chance to ask questions of both our experts, either live on the day or by sending us questions in advance at info@cirm.ca.gov.

We’ll post reminders on Facebook so make sure to follow us. But for now, mark the date and time on your diary and please feel free to share this information with anyone you think might be interested.

It promises to be a fascinating event.

 

 

Coming up with a stem cell FIX for a life-threatening blood disorder

Hemophilia

A promising new treatment option for hemophiliacs is in the works at the Salk Institute for Biological Sciences. Patients with Hemophilia B experience uncontrolled, and sometimes life threatening, bleeding due to loss or improper function of Factor IX (FIX), a protein involved in blood clotting. There is no cure for the disease and patients rely on routine infusions of FIX to prevent excessive blood loss. As you can imagine, this treatment regimen is both time consuming and expensive, while also becoming less effective over time.

Salk researchers, partially funded by CIRM, aimed to develop a more long-term solution for this devastating disease by using the body’s own cells to fix the problem.

In the study, published in the journal Cell Reports, They harvested blood cells from hemophiliacs and turned them into iPSCs (induced pluripotent stem cells), which are able to turn into any cell type. Using gene editing, they repaired the iPSCs so they could produce FIX and then turned the iPSCs into liver cells, the cell type that naturally produces FIX in healthy individuals.

One step therapy

To test whether these FIX-producing liver cells were able to reduce excess blood loss, the scientists injected the repaired human cells into a hemophiliac mouse. The results were very encouraging; they saw a greater than two-fold increase in clotting efficiency in the mice, reaching about a quarter of normal activity. This is particularly promising because other studies showed that increasing FIX activity to this level in hemophiliac humans significantly reduces bleeding rates. On top of that they also observed that these cells were able to survive and produce FIX for up to a year in the mice.

In a news release Suvasini Ramaswamy, the first author of the paper, said this method could eliminate the need for multiple treatments, as well as avoiding the immunosuppressive therapy that would be required for a whole liver transplant.

“The appeal of a cell-based approach is that you minimize the number of treatments that a patient needs. Rather than constant injections, you can do this in one shot.”

While these results provide an exciting new avenue in hemophilia treatment, there is still much more work that needs to be done before this type of treatment can be used in humans. This approach, however, is particularly exciting because it provides an important proof of principle that combining stem cell reprogramming with genetic engineering can lead to life-changing breakthroughs for treating genetic diseases that are not currently curable.

 

 

Stem Cell Agency’s supporting role in advancing research for rare diseases

Orchard

The recent agreement transferring GSK’s rare disease gene therapies to Orchard Therapeutics was good news for both companies and for the patients who are hoping this research could lead to new treatments, even cures, for some rare diseases. It was also good news for CIRM, which played a key role in helping Orchard grow to the point where this deal was possible.

In a news releaseMaria Millan, CIRM’s President & CEO, said:

“At CIRM, our value proposition is centered around our ability to advance the field of regenerative medicine in many different ways. Our funding and partnership has enabled the smooth transfer of Dr. Kohn’s technology from the academic to the industry setting while conducting this important pivotal clinical trial. With our help, Orchard was able to attract more outside investment and now it is able to grow its pipeline utilizing this platform gene therapy approach.”

Under the deal, GSK not only transfers its rare disease gene therapy portfolio to Orchard, it also becomes a shareholder in the company with a 19.9 percent equity stake. GSK is also eligible to receive royalties and commercial milestone payments. This agreement is both a recognition of Orchard’s expertise in this area, and the financial potential of developing treatments for rare conditions.

Dr. Millan says it’s further proof that the agency’s impact on the field of regenerative medicine extends far beyond the funding it offers companies like Orchard.

“Accelerating stem cell therapies to patients with unmet medical needs involves a lot more than just funding research; it involves supporting the research at every stage and creating partnerships to help it fulfill its potential. We invest when others are not ready to take a chance on a promising but early stage project. That early support not only helps the scientists get the data they need to show their work has potential, but it also takes some of the risk out of investments by venture capitalists or larger pharmaceutical companies.”

CIRM’s early support helped UCLA’s Don Kohn, MD, develop a stem cell therapy for severe combined immunodeficiency (SCID). This therapy is now Orchard’s lead program in ADA-SCID, OTL-101.

Sohel Talib, CIRM’s Associate Director Therapeutics and Industry Alliance, says this approach has transformed the lives of dozens of children born with this usually fatal immune disorder.

“This gene correction approach for severe combined immunodeficiency (SCID) has already transformed the lives of dozens of children treated in early trials and CIRM is pleased to be a partner on the confirmatory trial for this transformative treatment for patients born with this fatal immune disorder.”

Dr. Donald B. Kohn UCLA MIMG BSCRC Faculty 180118Dr. Kohn, now a member of Orchard’s scientific advisory board, said:

“CIRM funding has been essential to the overall success of my work, supporting me in navigating the complex regulatory steps of drug development, including interactions with FDA and toxicology studies that enhanced and helped drive the ADA-SCID clinical trial.”

CIRM funding has allowed Orchard Therapeutics to expand its technical operations footprint in California, which now includes facilities in Foster City and Menlo Park, bringing new jobs and generating taxes for the state and local community.

Mark Rothera, Orchard’s President and CEO, commented:

“The partnership with CIRM has been an important catalyst in the continued growth of Orchard Therapeutics as a leading company transforming the lives of patients with rare diseases through innovative gene therapies. The funding and advice from CIRM allowed Orchard to accelerate the development of OTL-101 and to build a manufacturing platform to support our development pipeline which includes 5 clinical and additional preclinical programs for potentially transformative gene therapies”.

Since CIRM was created by the voters of California the Agency has been able to use its support for research to leverage an additional $1.9 billion in funds for California. That money comes in the form of co-funding from companies to support their own projects, partnerships between outside investors or industry groups with CIRM-funded companies to help advance research, and additional funding that companies are able to attract to a project because of CIRM funding.

Livers skip stem cells, build missing structures from scratch via direct cell identity conversion

Stem cells…eh, who needs them anyway?!

That’s what you might be thinking after today, at least for some forms of liver disease. That’s because a team of researchers from UCSF and Cincinnati Children’s Hospital Medical Center just published results in Nature showing liver cells can directly change identity, or transdifferentiate, in order to build, from scratch, structures missing due to disease.

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The liver contains a network of tubes called bile ducts that carry fat-digesting bile to the small intestine via the gallbladder.
Image: National Cancer Inst.

The extraordinary regenerative power of the liver in animals is well-documented. A human liver, for instance, can fully regrow from just 25% of its original mass. That’s thanks to the hepatocyte, the main type of liver cell, that has the ability to replenish pre-existing tissue lost due to disease or injury. What hasn’t been as clear cut, is whether the hepatocyte has the capacity to change identity and build functional liver structures from scratch that never developed in the first place due to genetic disorders.

To examine that possibility, the study – funded in part by CIRM – focused on an inherited liver disease called Alagille syndrome which is caused by abnormal bile ducts. Produced by the liver, bile helps digest fats in our diet. It travels from the liver via bile ducts – tree branch-like tube structures in the liver – to the gallbladder, where it’s stored before moving on to the small intestine. In Alagille syndrome, the bile ducts are fewer in number, narrower in size or altogether missing. As a result, the bile builds up in the liver causing scarring and severe damage. Nearly half of all those with Alagille syndrome, require a liver transplant, usually in childhood.

The research team mimicked the symptoms of Alagille syndrome in mice by genetically engineering the animals to lack cholangiocytes, the cells that form bile ducts. Sure enough, liver damage from bile buildup was observed in these mice at birth due to the missing bile duct structures, also called the biliary tree. However, 90% of the mice survived and eventually formed a functional biliary tree. The team went on to show, for the first time, that the hepatocytes had converted en masse into cholangiocytes and created the wholly new bile ducts.

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Mice that mimic Alagille syndrome are born without the branches of the biliary tree, an important “plumbing system” in the liver (A), but show a near-normal biliary system as adults (B). To build the missing branches, liver cells switch identity and form tubes, shown in green, that connect to the trunk of the biliary tree, shown in blue (C). Image: Cincinnati Children’s

The underlying molecular mechanisms of this process were further examined. The researchers showed that the lack of a particular gene activity pathway due to the absence of cholangiocytes during development causes a replacement pathway, stimulated by a protein called TGF-beta, to kick into gear. As a result, the hepatocytes convert into cholangiocytes and form bile ducts. To make a direct connection with the human form of the disease, the researchers found evidence that TGF-beta is active in the liver samples of some patients but not in the livers from healthy individuals.

With this Alagille syndrome mouse model in hand, the researchers want to identify which transcription factors – proteins that bind DNA and regulate gene activity – are involved in changing the liver cells into bile duct cells. Holger Willenbring, MD, PhD, a senior author and CIRM grantee, explained the rationale behind this approach in a press release:

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Holger Willenbring

“Using transcription factors to make bile ducts from hepatocytes has potential as a safe and effective therapy. With our finding that an entire biliary system can be ‘retrofitted’ in the mouse liver, I am encouraged that this eventually will work in patients.”

So rather than developing a stem cell-based therapy in the lab which is then transplanted into a patient, this approach would rely on stimulating the regenerative capacity of liver cells that are already inside the body. And if it eventually works in patients with Alagille syndrome, which only affects 1 in 30,000, it’s possible it could be applied to other liver diseases as well.

Therapies Targeting Cancer, Deadly Immune Disorder and Life-Threatening Blood Condition Get Almost $32 Million Boost from CIRM Board

An innovative therapy that uses a patient’s own immune system to attack cancer stem cells is one of three new clinical trials approved for funding by CIRM’s Governing Board.

Researchers at the Stanford University School of Medicine were awarded $11.9 million to test their Chimeric Antigen Receptor (CAR) T Cell Therapy in patients with B cell leukemias who have relapsed or are not responding after standard treatments, such as chemotherapy.CDR774647-750Researchers take a patient’s own T cells (a type of immune cell) and genetically re-engineer them to recognize two target proteins on the surface of cancer cells, triggering their destruction. In addition, some of the T cells will form memory stem cells that will survive for years and continue to survey the body, killing any new or surviving cancer cells.

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Maria T. Millan

“When a patient is told that their cancer has returned it can be devastating news,” says Maria T. Millan, MD, President & CEO of CIRM. “CAR T cell therapy is an exciting and promising new approach that offers us a way to help patients fight back against a relapse, using their own cells to target and destroy the cancer.”

 

 

Sangamo-logoThe CIRM Board also approved $8 million for Sangamo Therapeutics, Inc. to test a new therapy for beta-thalassemia, a severe form of anemia (lack of healthy red blood cells) caused by mutations in the beta hemoglobin gene. Patients with this genetic disorder require frequent blood transfusions for survival and have a life expectancy of only 30-50 years. The Sangamo team will take a patient’s own blood stem cells and, using a gene-editing technology called zinc finger nuclease (ZFN), turn on a different hemoglobin gene (gamma hemoglobin) that can functionally substitute for the mutant gene. The modified blood stem cells will be given back to the patient, where they will give rise to functional red blood cells, and potentially eliminate the need for chronic transfusions and its associated complications.

UCSFvs1_bl_a_master_brand@2xThe third clinical trial approved is a $12 million grant to UC San Francisco for a treatment to restore the defective immune system of children born with severe combined immunodeficiency (SCID), a genetic blood disorder in which even a mild infection can be fatal. This condition is also called “bubble baby disease” because in the past children were kept inside sterile plastic bubbles to protect them from infection. This trial will focus on SCID patients who have mutations in a gene called Artemis, the most difficult form of SCID to treat using a standard bone marrow transplant from a healthy donor. The team will genetically modify the patient’s own blood stem cells with a functional copy of Artemis, with the goal of creating a functional immune system.

CIRM has funded two other clinical trials targeting different approaches to different forms of SCID. In one, carried out by UCLA and Orchard Therapeutics, 50 children have been treated and all 50 are considered functionally cured.

This brings the number of clinical trials funded by CIRM to 48, 42 of which are active. There are 11 other projects in the clinical trial stage where CIRM funded the early stage research.

The Story of a South African Bubble Boy and a Gene Therapy That Gave Him His Life Back

Ayaan Isaacs, health24

Ayaan Isaacs was born in South Africa on March 4th, 2016 as a seemingly healthy baby. But only a few days in to life, he contracted a life-threatening liver infection. He thankfully survived, only to have the doctors discover a few weeks later that he had something much more troubling – a rare disease that left him without a functioning immune system.

Ayaan was diagnosed with X-linked severe combined immunodeficiency (SCID), which is often referred to as ‘bubble baby’ disease because patients are extremely susceptible to infection and must live in sterile environments. SCID patients can be cured with a blood stem cell transplant if they have a genetically matched donor. Unfortunately for Ayaan, only a partially matched donor was available, which doesn’t guarantee a positive outcome.

Ayaan’s parents were desperate for an alternative treatment to save Ayaan’s life. It was at this point that they learned about a clinical trial at St. Jude Children’s Research hospital in Memphis, Tennessee. The trial is treating SCID patients with a stem cell gene therapy that aims to give them a new functioning immune system. The therapy involves extracting the patient’s blood-forming stem cells and genetically correcting the mutation that causes SCID. The corrected blood stem cells are then transplanted back into the patient where they rebuild a healthy immune system.

Ayaan was able to enroll in the trial, and he was the first child in Africa to receive this life-saving gene therapy treatment. Ayaan’s journey with bubble boy disease was featured by South Africa’s health24 earlier this year. In the article, his mom Shamma Sheik talked about the hope that this gene therapy treatment brought to their family.

“No child should have to die just because they are unable to find a donor. Gene therapy offered Ayaan a chance at life that he ordinarily would not have had. I was fortunate to have found an alternative therapy that is working and already showing remarkable results. We are mindful that this is still an experimental treatment and there are complications that can arise; however, I am very optimistic that he will return to South Africa with a functioning immune system.”

Carte Blanche, an investigative journalism program in South Africa, did a feature video of Ayaan in February. Although the video is no longer available on their website, it did reveal that four months after Ayaan’s treatment, his condition started to improve suggesting that the treatment was potentially working.

We’ve written previously about another young boy named Ronnie who was diagnosed with X-linked SCID days after he was born. Ronnie also received the St. Jude stem cell gene therapy in a CIRM-funded clinical trial at the UCSF Benioff Children’s Hospital. Ronnie was treated when he was six months old and just celebrated his first birthday as a healthy, vibrant kid thanks to this trial. You can hear more about Ronnie’s moving story from his dad, Pawash Priyank, in the video below.

Our hope is that powerful stories like Ayaan’s and Ronnie’s will raise awareness about SCID and the promising potential of stem cell gene therapies to cure patients of this life-threatening immune disease.

Ronnie and his parents celebrating his 1st birthday. (Photo courtesy of Pawash Priyank)


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