Boosting the blood system after life-saving therapy

Following radiation, the bone marrow shows nearly complete loss of blood cells in mice (left). Mice treated with the PTP-sigma inhibitor displayed rapid recovery of blood cells (purple, right): Photo Courtesy UCLA

Chemotherapy and radiation are two of the front-line weapons in treating cancer. They can be effective, even life-saving, but they can also be brutal, taking a toll on the body that lasts for months. Now a team at UCLA has developed a therapy that might enable the body to bounce back faster after chemo and radiation, and even make treatments like bone marrow transplants easier on patients.

First a little background. Some cancer treatments use chemotherapy and radiation to kill the cancer, but they can also damage other cells, including those in the bone marrow responsible for making blood stem cells. Those cells eventually recover but it can take weeks or months, and during that time the patient may feel fatigue and be more susceptible to infections and other problems.

In a CIRM-supported study, UCLA’s Dr. John Chute and his team developed a drug that speeds up the process of regenerating a new blood supply. The research is published in the journal Nature Communications.

They focused their attention on a protein called PTP-sigma that is found in blood stem cells and acts as a kind of brake on the regeneration of those cells. Previous studies by Dr. Chute showed that, after undergoing radiation, mice that have less PTP-sigma were able to regenerate their blood stem cells faster than mice that had normal levels of the protein.

John Chute: Photo courtesy UCLA

So they set out to identify something that could help reduce levels of PTP-sigma without affecting other cells. They first identified an organic compound with the charming name of 6545075 (Chembridge) that was reported to be effective against PTP-sigma. Then they searched a library of 80,000 different small molecules to find something similar to 6545075 (and this is why science takes so long).

From that group they developed more than 100 different drug candidates to see which, if any, were effective against PTP-sigma. Finally, they found a promising candidate, called DJ009. In laboratory tests DJ009 proved itself effective in blocking PTP-sigma in human blood stem cells.

They then tested DJ009 in mice that were given high doses of radiation. In a news release Dr. Chute said the results were very encouraging:

“The potency of this compound in animal models was very high. It accelerated the recovery of blood stem cells, white blood cells and other components of the blood system necessary for survival. If found to be safe in humans, it could lessen infections and allow people to be discharged from the hospital earlier.”

Of the radiated mice, most that were given DJ009 survived. In comparison, those that didn’t get DJ009 died within three weeks.

They saw similar benefits in mice given chemotherapy. Mice with DJ009 saw their white blood cells – key components of the immune system – return to normal within two weeks. The untreated mice had dangerously low levels of those cells at the same point.

It’s encouraging work and the team are already getting ready for more research so they can validate their findings and hopefully take the next step towards testing this in people in clinical trials.

HIV eliminated from mice using CRISPR and LASER ART

Dr. Kamel Khalili

In the United States alone, there are approximately 1.1 million people living with Human immunodeficiency virus (HIV), a virus that weakens the immune system by destroying important cells that fight off disease and infection. This number is much larger on a global scale, with 36.9 million people living with HIV as of 2017. If left untreated, the immune system becomes so weakened that the condition worsens into acquired immunodeficiency syndrome (AIDS), which is usually fatal.

Current treatment for HIV focuses on the use of antiretroviral therapy (ART). This treatment is able to suppress replication of the virus, but it does not eliminate it from the body entirely. In order to be sustainable, ART must be taken throughout the course of a lifetime, otherwise HIV rebounds and the replication of the virus renews, fueling the development of AIDS.

The ability of HIV to rebound is related to the fact that it is able to integrate its DNA into various cells inside the body and beyond the reach of ART. Here they are able to remain dormant and ready to replicate as soon as ART is not interfering. It is because of this that ART is not sufficient on its own to cure HIV, but a group of scientists have uncovered a promising breakthrough to change that.

In a major collaboration, researchers at the Lewis Katz School of Medicine at Temple University and the University of Nebraska Medical Center (UNMC) have for the first time eliminated HIV from the DNA of living mice. This study marks a critical step toward the development of a possible cure for human HIV infection.

The team of researchers was able to do this with the help of a new technology called long-acting slow-effective release (LASER) ART. LASER ART is able to target HIV sanctuaries and maintain replication at low levels for extended periods of time. Immediately after administering LASER ART, the team used a gene editing technology known as CRISPR to remove the final remnants of HIV DNA hidden inside cells.

In a press release, Dr. Kamel Khalili, senior investigator for this study, was quoted as saying,

“Our study shows that treatment to suppress HIV replication and gene editing therapy, when given sequentially, can eliminate HIV from cells and organs of infected animals…We now have a clear path to move ahead to trials in non-human primates and possibly clinical trials in human patients within the year.”

The full results of this study were published in Nature Communications.

To learn more about how CRISPR technology works, you can read more about it on a previous blog post.

Muscle stem cells provide insight into treatment of muscular dystrophies and aging muscles

Dr. Alessandra Sacco, associate professor in the Development, Aging and Regeneration Program at Sanford Burnham Prebys.

Muscles are a vital part of the body that enable us to walk, run, lift, and do everyday activities. When muscles start to deteriorate, we start to have difficulty performing these activities, which severely limits quality of life and autonomy. Typically, this becomes more commonplace as we age and is known as sarcopenia, which affects nearly ten percent of adults over the age of 50 and nearly half of individuals in their 80s.

However, there are other instances where this happens much more rapidly and early on due to genetic disease. These are commonly known as muscular dystrophies, which consist of more than 30 genetic diseases characterized by progressive muscle weakness and degeneration. A cure does not currently exist.

Regardless of the cause of the muscle deterioration, scientists at Sanford Burnham Prebys have uncovered how to potentially promote growth inside stem cells found within the muscle, thereby promoting muscle growth. In a mouse model study funded in part by CIRM and published in Nature Communications, Dr. Alessandra Sacco, senior author of the paper, and her team describe how a signaling pathway, along with a specific protein, can help regulate what muscle stem cells do.

Muscle stem cells can do two things, they either become adult muscle cells or self-renew to replenish the stem cell population. The paper discusses how the signaling pathway and specific protein are crucial for muscle stem cell differentiation and muscle growth, both of which are needed to prevent deterioration. Their aim is to use this knowledge to develop therapeutic targets that can aid with muscle growth.

Dr. Alessandra Sacco is quoted in an article as saying,

“Muscle stem cells can ‘burn out’ trying to regenerate tissue during the natural aging process or due to chronic muscle disease. We believe we have found promising drug targets that direct muscle stem cells to ‘make the right decision’ and stimulate muscle repair, potentially helping muscle tissue regeneration and maintaining tissue function in chronic conditions such as muscular dystrophy and aging.”

Targeted treatment for pediatric brain tumors shows promising results

Image of medulloblastoma

Imagine sitting in the doctor’s office and being told the heartbreaking news that your child has been diagnosed with a malignant brain tumor. As one might expect, the doctor states that the most effective treatment option is typically a combination of chemotherapy and radiation. However, the doctor reveals that there are additional risks to take into account that apply to children. Since children’s tiny bodies are still growing and developing, chemotherapy and radiation can cause long-term side effects such as intellectual disabilities. As a parent, it is painful enough to have to watch a child go through chemotherapy and radiation without adding permanent damage into the fold.

Sadly, this scenario is not unique. Medulloblastoma is the most prevalent form of a pediatric brain tumor with more than 350 children diagnosed with cancer each year. There are four distinct subtypes of medulloblastoma, with the deadliest being known as Group 3.

Researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) are trying to minimize the collateral damage by finding personalized treatments that reduce side effects while remaining effective. Scientists at SBP are working with an inhibitor known as LSD1 that specifically targets Group 3 medulloblastoma in a mouse model. The study, published in Nature Communications, showed that the drug dramatically decreased the size of tumors grown under the mouse’s skin by shrinking the cancer by more than 80 percent. This suggested that it could also be effective against patients’ tumors if it could be delivered to the brain. The LSD1 inhibitor has shown promise in clinical trials, where it has been tested for treating other types of cancer.

According to Robert Wechsler-Reya, Ph.D., senior author of the paper and director of the Tumor Initiation and Maintenance Program at SBP: “Our lab is working to understand the genetic pathways that drive medulloblastoma so we can find better ways to intervene and treat tumors. This study shows that a personalized treatment based upon a patient’s specific tumor type might be within our reach.”

Dr. Wechsler-Reya’s work on medulloblastoma was, in part, funded by the CIRM (LA1-01747) in the form of a Research Leadership Award for $5,226,049.

Stories that Caught Our Eye: New ways to heal old bones; and keeping track of cells once they are inside you

broken bones

How Youth Factor Can Help Repair Old Bones

As we get older things that used to heal quickly tend to take a little longer to get better. In some cases, a lot longer. Take bones for example. A fracture in someone who is in their 70’s often doesn’t heal as quickly, or completely, as in someone much younger. For years researchers have been working on ways to change that. Now we may be one step closer to doing just that.

We know that using blood stem cells can help speed up healing for bone fractures (CIRM is funding work on that) and now researchers at Duke Health believe they have figured out how that works.

The research, published in the journal Nature Communications, identifies what the Duke team call the “youth factor” inside bone marrow stem cells. It’s a type of white blood cell called a macrophage. They say the proteins these macrophages produce help stimulate bone repair.

In a news story in Medicine News Line  Benjamin Alman, senior author on the study, says:

“While macrophages are known to play a role in repair and regeneration, prior studies do not identify secreted factors responsible for the effect. Here we show that young macrophage cells play a role in the rejuvenation process, and injection of one of the factors produced by the young cells into a fracture in old mice rejuvenates the pace of repair. This suggests a new therapeutic approach to fracture rejuvenation.”

Next step, testing this in people.

A new way to track stem cells in the body

It’s one thing to transplant stem cells into a person’s body. It’s another to know that they are going to go where you want them to and do what you want them to. University of Washington researchers have invented a device that doesn’t just track where the cells end up, but also what happens to them along the way.

The device is called “CellTagging”, and in an article in Health Medicine Network, Samantha Morris, one of the lead researchers says this could help in better understanding how to use stem cells to grow replacement tissues and organs.

“There is a lot of interest in the potential of regenerative medicine — growing tissues and organs in labs — to test new drugs, for example, or for transplants one day. But we need to understand how the reprogramming process works. We want to know if the process for converting skin cells to heart cells is the same as for liver cells or brain cells. What are the special conditions necessary to turn one cell type into any other cell type? We designed this tool to help answer these questions.”

In the study, published in the journal Nature, the researchers explain how they use a virus to insert tiny DNA “barcodes” into cells and that as the cells travel through the body they are able to track them.

Morris says this could help scientists better understand the conditions needed to more effectively program cells to do what we want them to.

“Right now, cell reprogramming is really inefficient. When you take one cell population, such as skin cells, and turn it into a different cell population — say intestinal cells — only about 1 percent of cells successfully reprogram. And because it’s such a rare event, scientists have thought it is likely to be a random process — there is some correct set of steps that a few cells randomly hit upon. We found the exact opposite. Our technology lets us see that if a cell starts down the right path to reprogramming very early in the process, all of its related sibling cells and their descendants are on the same page, doing the same thing.”

For the first time, scientists entirely reprogram human skin cells to iPSCs using CRISPR

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CRISPR iPSC colony of human skin cells showing expression of SOX2 and TRA-1-60, markers of human embryonic pluripotent stem cells

Back in 2012, Shinya Yamanaka was awarded the Nobel Prize in Physiology or Medicine for his group’s identification of “Yamanaka Factors,” a group of genes that are capable of turning ordinary skin cells into induced pluripotentent stem cells (iPSCs) which have the ability to become any type of cell within the body. Discovery of iPSCs was, and has been, groundbreaking because it not only allows for unprecedented avenues to study human disease, but also has implications for using a patient’s own cells to treat a wide variety of diseases.

Recently, Timo Otonkoski’s group at the University of Helsinki along with Juha Kere’s group at the Karolinska Institutet and King’s College, London have found a way to program iPSCs from skin cells using CRISPR, a gene editing technology. Their approach allows for the induction, or turning on of iPSCs using the cells own DNA, instead of introducing the previously identified Yamanka Factors into cells of interest.

As detailed in their study, published in the journal Nature Communications, this is the first instance of mature human cells being completely reprogrammed into pluripotent cells using only CRISPR. Instead of using the canonical CRISPR system that allows the CAS9 protein (an enzyme that is able to cut DNA, thus rendering a gene of interest dysfunctional) to mutate any gene of interest, this group used a modified version of the CAS9 protein, which allows them to turn on or off the gene that CAS9 is targeted to.

The robustness of their approach lies in the researcher’s identification of a DNA sequence that is commonly found near genes involved in embryonic development. As CAS9 needs to be guided to genes of interest to do its job, identification of this common motif allows multiple genes associated with pluripotency to be activated in mature human skin cells, and greatly increased the efficiency and effectiveness of this approach.

In a press release, Dr. Otonkoski further highlights the novelty and viability of this approach:

“…Reprogramming based on activation of endogenous genes rather than overexpression of transgenes is…theoretically a more physiological way of controlling cell fate and may result in more normal cells…”

 

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

Mosquito

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.

Stem Cell Roundup: Improving muscle function in muscular dystrophy; Building a better brain; Boosting efficiency in making iPSC’s

Here are the stem cell stories that caught our eye this week.

Photos of the week

TGIF! We’re so excited that the weekend is here that we are sharing not one but TWO amazing stem cell photos of the week.

RMI IntestinalChip

Image caption: Cells of a human intestinal lining, after being placed in an Intestine-Chip, form intestinal folds as they do in the human body. (Photo credit: Cedars-Sinai Board of Governors Regenerative Medicine Institute)

Photo #1 is borrowed from a blog we wrote earlier this week about a new stem cell-based path to personalized medicine. Scientists at Cedars-Sinai are collaborating with a company called Emulate to create intestines-on-a-chip using human stem cells. Their goal is to create 3D-organoids that represent the human gut, grow them on chips, and use these gut-chips to screen for precision medicines that could help patients with intestinal diseases. You can read more about this gut-tastic research here.

Young mouse heart 800x533

Image caption: UCLA scientists used four different fluorescent-colored proteins to determine the origin of cardiomyocytes in mice. (Image credit: UCLA Broad Stem Cell Research Center/Nature Communications)

Photo #2 is another beautiful fluorescent image, this time of a cross-section of a mouse heart. CIRM-funded scientists from UCLA Broad Stem Cell Research Center are tracking the fate of stem cells in the developing mouse heart in hopes of finding new insights that could lead to stem cell-based therapies for heart attack victims. Their research was published this week in the journal Nature Communications and you can read more about it in a UCLA news release.

Stem cell injection improves muscle function in muscular dystrophy mice

Another study by CIRM-funded Cedars-Sinai scientists came out this week in Stem Cell Reports. They discovered that they could improve muscle function in mice with muscular dystrophy by injecting cardiac progenitor cells into their hearts. The injected cells not only improved heart function in these mice, but also improved muscle function throughout their bodies. The effects were due to the release of microscopic vesicles called exosomes by the injected cells. These cells are currently being used in a CIRM-funded clinical trial by Capricor therapeutics for patients with Duchenne muscular dystrophy.

How to build a better brain (blob)

For years stem cell researchers have been looking for ways to create “mini brains”, to better understand how our own brains work and develop new ways to repair damage. So far, the best they have done is to create blobs, clusters of cells that resemble some parts of the brain. But now researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA have come up with a new method they think can advance the field.

Their approach is explained in a fascinating article in the journal Science News, where lead researcher Bennet Novitch says finding the right method is like being a chef:

“It’s like making a cake: You have many different ways in which you can do it. There are all sorts of little tricks that people have come up with to overcome some of the common challenges.”

Brain cake. Yum.

A more efficient way to make iPS cells

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Shinya Yamanaka. (Image source: Ko Sasaki, New York Times)

In 2006 Shinya Yamanaka discovered a way to take ordinary adult cells and reprogram them into embryonic-like stem cells that have the ability to turn into any other cell in the body. He called these cells induced pluripotent stem cells or iPSC’s. Since then researchers have been using these iPSC’s to try and develop new treatments for deadly diseases.

There’s been a big problem, however. Making these cells is really tricky and current methods are really inefficient. Out of a batch of, say, 1,000 cells sometimes only one or two are turned into iPSCs. Obviously, this slows down the pace of research.

Now researchers in Colorado have found a way they say dramatically improves on that. The team says it has to do with controlling the precise levels of reprogramming factors and microRNA and…. Well, you can read how they did it in a news release on Eurekalert.

 

 

 

Stem cell stories that caught our eye: How Zika may impact adult brains; Move over CRISPR there’s a new kid in town; How our bodies store fat

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

zika

Zika mosquito

Zika virus could impact adult brains

It’s not just a baby’s developing brain that is vulnerable to the Zika virus, adult brains may be too. A new study shows that some stem cells that help repair damage in the adult brain can be impacted by Zika. This is the first time we’ve had any indication this could be a problem in a fully developed brain.

The study, in the journal Cell Stem Cell, looked at neural progenitors, a  stem cell that plays an important role in helping replace or repair damaged neurons, or nerve cells, in the brain. The researchers exposed the cells to the Zika virus and found that it infected the cells, causing some of the cells to die, and also limited the ability of the cells to proliferate.

In an interview in Healthday, Sujan Shresta, a researcher at the La Jolla Institute for Allergy and Immunology and one of the lead authors of the study, says although their work was done in adult mice, it may have implications for people:

“Zika can clearly enter the brains of adults and can wreak havoc. But it’s a complex disease, it’s catastrophic for early brain development, yet the majority of adults who are infected with Zika rarely show detectable symptoms. Its effect on the adult brain may be more subtle and now we know what to look for.”

Move over CRISPR, there’s a new gene-editing tool in town

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Jennifer Lopez: Photo courtesy MTV

For much of the last year the hottest topic in stem cell and gene editing research has been CRISPR and the ease with which it can be used to edit genes. It’s so hot that apparently it’s the title of an upcoming TV show starring Jeniffer Lopez.

But hold on J-Lo, a new study in Nature Communications says by the time the show is on the air it may be old hat. Researchers at Carnegie Mellon and Yale University have developed a new gene-editing system, one they claim is easier to use and more accurate than CRISPR. And to prove it, they say they have successfully cured a genetic blood disorder in mice, using a simple IV approach.

Tools like CRISPR use enzymes to cut open sections of DNA to edit a specific gene. It’s like using a pair of scissors to cut a piece of string that has a big knot in the middle; you cut out the knot then join the ends of the string together. The problem with CRISPR is that the enzymes it uses are quite large and hard to use in a living animal – let alone a human – so they have to remove the target cells from the body and do the editing in the lab. Another problem is that CRISPR sometimes cuts sections of DNA that the researchers don’t want cut and could lead to dangerous side effects.

Greater precision

The Carnegie Mellon/Yale team say their new method avoids both problems. They use nanoparticles that contain molecules made from peptide nucleic acid (PNA), a kind of artificial form of DNA. This PNA is engineered to be able to cut open DNA and bind to a specific target without cutting anything else.

The team used this approach to target the mutated gene in beta thalassemia, a blood disorder that can be fatal if left untreated. The therapy binds to the malfunctioning gene, enabling the body’s own DNA repair system to correct the problem.

In a news story in Science Daily Danith Ly, one of the lead authors on the study, says even though the technique was successful in editing the target genes just 7 percent of the time, that is way more than the 0.1 percent rate most other gene editing tools achieve.

“The effect may only be 7 percent, but that’s curative. In the case of this particular disease model, you don’t need a lot of correction. You don’t need 100 percent to see the phenotype return to normal.”

Hormone that controls if and when fat cells mature

Obesity is one of the fastest growing public health problems in the US and globally. Understanding the mechanisms behind how that happens could be key to finding ways to address it. Now researchers at Stanford University think they may have uncovered an important part of the answer.

Their findings, reported in Science Signaling, show that mature fat cells produce a hormone called Adamts1 which acts like a switch for surrounding stem cells, determining if they change into fat-storing cells.   People who eat a high-fat diet experience a change in their Adamst1 production, and that triggers the nearby stem cells to specialize and start storing fat.

There are still a lot of questions to be answered about Adamst1, including whether it acts alone or in conjunction with other as yet unknown hormones. But in an article in Health Canal, Brian Feldman, the senior author of the study, says they can now start looking at potential use of Adamst1 to fight obesity.

“That won’t be a simple answer. If you block fat formation, extra calories have to go somewhere in the body, and sending them somewhere else outside fat cells could be more detrimental to metabolism. We know from other researchers’ work that liver and muscle are both bad places to store fat, for example. We do think there are going to be opportunities for new treatments based on our discoveries, but not by simply blocking fat formation alone.”