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Injectable photoreactive gel and biological adhesive help new cartilage grow
Injectable photoreactive gel and biological adhesive help new cartilage grow
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Introduction
This is a production of the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health
Host-Margot Kern: Every year, hundreds of thousands of Americans undergo surgery to repair torn hyaline cartilage—that is the tough, flexible tissue that acts as a shock absorber between bones. Yet, outcomes for cartilage repair are typically poor. The reason is that unlike other tissues in the body, cartilage lacks its own blood supply, which normally bathes damaged tissue and provide factors that promote regeneration.
Host-Margot Kern: Currently, the first-line therapy for cartilage repair is a technique called microfracture surgery in which tiny holes are drilled into the bone located directly below missing cartilage in order to release bone marrow into the damaged space. Because bone marrow contains a mixture of stem cells and blood, the resulting clot provides an enriched environment that promotes cartilage regeneration.
Host-Margot Kern: Yet, only half of these surgeries are considered successful in the long-term. One issue is that the regenerated cartilage is a mixture of smooth hyaline cartilage and fibrous scar-like tissue. This fibrocartilage doesn’t function as well as pure hyaline cartilage as a cushion between joints. Another issue is that the regenerated cartilage rarely integrates fully with the patient’s existing cartilage and this prevents it from becoming functional.
Host-Margot Kern: Dr. Rosemarie Hunziker is a program director in charge of overseeing NIBIB’s grant portfolio for tissue engineering. Over the years, she’s witnessed many attempts by doctors and researchers to devise novel techniques for cartilage repair.
Hunziker: I’ve seen just about everything from harvesting healthy cartilage from another part of the body and then directly transplanting it, although way through to complex formulations of scaffolds and cells grown in the lab and then implanted as a unit. The problem has always been, how to get the newly-generated tissue to integrate into a patients’ existing tissue so that it becomes functional.
Host-Margot Kern: But Dr. Jennifer Elisseeff, a tissue engineer at Johns Hopkins University, may have provided a promising new alternative. Elisseeff builds hyaline cartilage in her lab, a process that involves planting chondrocytes—which are cartilage-producing cells—into a biological scaffold and then incubating them in conditions similar to those found in the human body. Elisseeff says choosing the right scaffold material is critical for producing high-quality cartilage.
Elisseeff: As we’ve been learning more about biomaterials and how cells respond to them, we’ve also learned that chondrocytes, the cells that make up cartilage, prefer to be in a softer material as the tissue’s developing.
Host-Margot Kern: Elisseeff’s lab creates hydrogel scaffolds, which are smooth, flexible, and have a high water content. Not only do these hydrogels encourage the production of hyaline cartilage, but they also deter the development of unwanted tissue.
Elisseeff: We want to reduce scar formation and bone formation and these types of hydrogel scaffolds are able to do that.
Host-Margot Kern: After several years of growing high-quality cartilage in the lab, Elisseeff predicted that if she could introduce her hydrogel scaffold into a patient following microfracture surgery, she might be able to influence the quality of the cartilage regenerated.
Host-Margot Kern: But implanting a scaffold into an irregularly shaped space where cartilage has broken off is no easy task. Even more difficult is getting the scaffold to adhere to the slippery walls of a patient’s surrounding cartilage, a step that’s crucial for the new cartilage to become functional.
Host-Margot Kern: With the support of NIBIB funding, Elisseeff began to develop two novel technologies to overcome these hurdles. The first was a photo-active hydrogel that could be injected as a liquid into an irregularly shaped cartilage defect and then solidified upon exposure to a light source. The second technology was a biological adhesive that could bond to both the hydrogel and to specific proteins found on the surface of cartilage tissue, essentially cementing the scaffold in place.
Elisseeff: We wanted to be able to bond the hydrogel in tough environments, and then it also serves a biological role to help stimulate tissue development at that fragile interface.
Host-Margot Kern: Elisseeff’s photo-active gel and biological adhesive were recently tested in a clinical trial involving 18 patients. Fifteen patients received microfracture with the gel/adhesive combo and three received microfracture alone.
Host-Margot Kern: The growth of new cartilage was evaluated post-surgery using an innovative MRI technique, also developed by an NIBIB grantee, Dr. Gary Gold of Stanford Univeristy. The technique can distinguish between fibrous and smooth cartilage and gives doctors a way to monitor cartilage growth at sequential time-points without conducting a tissue biopsy, a procedure that’s detrimental even when taking just a tiny amount of cartilage.
Host-Margot Kern: In the trial 84% of the defect was filled with new cartilage in patients who received the gel/adhesive combo compared to just 64% in patients who received microfracture alone. And this new cartilage closely resembled the patient’s native cartilage at six months as verified by MRI. Additionally, patients who received the gel/adhesive combo reported a decrease in pain at six months post-surgery.
Host-Margot Kern: Hunziker says the study is exciting because it combines advancements in the fields of bioimaging and bioengineering to solve a long-standing problem in the field of cartilage repair.
Hunziker: Dr. Elisseeff’s lab may have found that elusive holy grail which is tissue integration. But it’s also important to note the significance of the novel MRI techniques that were used here to evaluate the new cartilage non-invasively. It was really a critical component to the study, because if we didn’t have it, we wouldn’t have an objective method for determining whether Elisseeff’s complex strategy was really working.
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Dedicated Breast CT
Narrator: This is a production by the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health.
Boone: A long time ago, I was thinking about how we could better det ect breast cancer. If you really wanted to improve contrast resolution for detecting breast cancer, CT would be the way to go.
Narrator: You’re listening to NIBIB grantee Dr. John Boone, Vice Chair of Radiology and Professor of Radiology and Biomedical Imaging at the University of California, Davis. Boone has spent the past decade developing a dedicated breast CT scanner that allows radiologists to view the breast in three dimensions.
Boone: Rather than acquiring just two images which is what a mammogram is, we actually have an apparatus that rotates around the breast 360 degrees and it acquires 500 images around the breast, and that provides the data set necessary to put that information into a computer and it comes out with a three dimensional set of images of the breast.
Narrator: The new technology could help radiologists detect hard-to-find tumors, especially in women who have dense breasts, which is commonly seen in younger woman. Dense breasts have higher percentages of connective and glandular tissue and when looking at a two dimensional x-ray of the breast, it can be difficult to view small tumors which may be located behind many layers of dense tissue. A CT scan which takes x-rays from many different angles could potentially reveal these tumors.
Boone: With breast CT, because we generate a 3D volume data set, the radiologist can scan through the images and that allows you to eliminate some of that overlying tissue and have a higher probability of detecting cancer we think.
Narrator: So why aren’t women currently offered a CT scan for routine cancer screening? The issue is that a conventional CT scan of the chest requires a hefty dose of radiation.
Boone: If you look at a whole body CT scanner, it scans the patients with the patient lying on the table and the x-ray tube and detectors go around the entire patient’s chest which means and that means you have to turn up the dose levels to penetrate the woman’s entire thorax.
Narrator: When Boone first announced his intention to build a CT scanner for detecting breast cancer, his colleagues were skeptical. They said there was no way he could screen for breast cancer using CT at a radiation dose comparable to mammography. But Boone was determined, and he began to design a novel CT scanner that didn’t require x-rays to pass through the chest.
Boone: The first step towards reducing radiation dose is to design a scanner that scans only the breast.
Narrator: In Boone’s scanner, a woman lies prone on a large table with her breast hanging through a hole in the middle. The scanner rotates just around the breast taking hundreds of x-rays without passing any through the chest.
Narrator: In 2001, using a computer simulation, Boone demonstrated that his proposed breast CT scanner would deliver a radiation dose comparable to standard mammography. In 2004, his lab became the first to image humans using dedicated breast CT. Since then, Boone has scanned over 600 women in a series of clinical trials and results from these showed that breast CT is significantly better at revealing tumors than traditional mammography.
Narrator: As an added bonus? Boone’s scanner doesn’t require compression of the breast.
Boone: Most women who have had mammograms recognize that the breasts are fairly aggressively compressed. In some women it’s very painful and in others it’s just sort of painful. We eliminate compression with breast CT.
Narrator: With support from NIBIB over the year, Boone has continued to develop his dedicated breast CT platform by incorporating additional imaging capabilities such as positron emission tomography also known as a PET scan
Narrator: In PET imaging, a patient is given an injection of a radioactive sugar molecule which quickly accumulates at tumor sites due to their increased rates of metabolic activity.
Boone: On our device, we actually do the CT scan and that gives a high- resolution anatomical picture of the breast. And then we do the PET scan and that picks up the emissions that are given off by the tumor that’s accumulated this agent. Usually we color that and lay it onto the grey scale breast image and it provides a pretty dramatic image of the tumor if there’s c a tumor there.
Narrator: Boone is also collaborating with the University of Chicago to develop computer aided-detection software in order to help radiologists view the hundreds of images generated by a CT scan.
Boone: We’re essentially asking radiologists to move from looking about two images per breast to looking at about 500 images per breast and radiologists are busy people and that would in general preclude any realistic deployment of such a device.
Narrator: Their goal is to produce software that uses algorithms to automatically detect tumors and then classify them as benign or malignant, a process that could both save time and improve the accuracy of diagnoses.
Narrator: Though dedicated breast CT is currently only approved for research purposes, Boone believes it won’t be too long before breast CT makes it into the clinic.
Boone: There are several companies around the world that are developing breast CT scanners. They have to go through the approval process which is quite lengthy but it would be realistic to think that breast CT technology will be available in perhaps 5-8 years in the United States.
Narrator: Until then, Boone and his lab will continue to improve the breast CT platform. They are currently focused on ways that CT could be used to provide real time image guidance for biopsy needle placement and minimally invasive tumor ablation.
Selective Repression of the Immune System
Narrator-Kern: This is a production by the National Institute of Biomedical Imaging and Bioengineering—part of the National Institutes of Health
Shea: The body has natural mechanisms for kind of shutting down an immune response that’s inappropriate and we’re really just looking to tap into those natural mechanisms.
Narrator-Kern: That’s Dr. Lonnie Shea, professor of bioengineering at Northwestern University referring to a recent advance in the pursuit of a safer, more efficient way to treat autoimmune diseases. Shea, in collaboration with Dr. Stephen Miller, also of Northwestern, have come up with a way to selectively inhibit the part of the immune system responsible for causing these diseases. Their most recent work, published in Nature Biotechnology, describes an innovative method for treating multiple sclerosis in mice. Dr. Miller explains just how the immune system is involved in the development of MS:
Miller: The immune response starts to attack the myelin membrane in the central nervous system. As a part of the disease, activated T cells enter the CNS and cause the destruction of myelin that leads to impairment of electrical function from the central nervous system to the muscles resulting in paralysis.
Narrator-Kern: Miller went on to explain that self-reactive T cells are responsible for generating a host of autoimmune diseases including rheumatoid arthritis and type 1 diabetes. Currently, autoimmune diseases are treated with a class of drugs called immunosuppressants, but Miller says these drugs have major drawbacks.
Miller: You’re not only trying to treat the autoimmune disease, you also make the individual susceptible to what we call opportunistic infections, or infections that those of us with healthy immune systems can normally deal with quite readily.
Miller: People on long-term immunosuppressant drugs are also susceptible to higher rates of cancer development because their immune system is not properly used to patrol the body looking for mutant cells that might become cancers.
Narrator-Kern: Miller says the holy grail of treating autoimmune disease is by a phenomenon called tolerance.
Miller: And what tolerance simply means is, in order to treat the disease, what you’re trying to do is specifically inactivate only the T cells that are responsible for damaging the self-tissue
Narrator-Kern: Miller’s lab has spent the past several decades developing a novel method for inducing tolerance. In the late 70’s, the lab discovered that if they attached antigens (or tiny portions of a protein) to dying white blood cells and then injected these antigen-coupled cells into a mouse, the mouse’s immune systems would become tolerant to the antigen.
Narrator-Kern: The method works because the body is constantly helping the immune system distinguish between antigens that belong to the body and those that are foreign and should be attacked. One way it does this is by presenting bits of protein found within dying cells to T-cells located in the spleen. Any T-cells capable of binding to these proteins become suppressed. Using this method, Miller’s lab was able to treat various animal models of autoimmune disease over the years, simply by changing the antigen coupled to the dying cells.
Narrator-Kern: But Miller anticipated problems translating his results in the lab to a potential treatment for humans. The issue was the need to use dying cells as antigen carriers:
Miller: Using the cellular therapy is extremely expensive and complex and requires that this therapy would be carried out at a large medical center.
Narrator-Kern: It was at this point that professor Lonnie Shea was pulled into the mix.
Shea: You know in our conversations, it became obvious that while his approach was incredibly successful and he’d done tremendous science in terms of understanding how that process worked that the translation would really be facilitated by using something other than the cell as the carrier for the peptide.
Narrator-Kern: That something ended up being microscopic biodegradable particles to which the lab attached specific antigens, in their case, a peptide of myelin.
Shea: A human hair is approximately a hundred microns in diameter, and so these particles are roughly 500 times smaller than a human hair.
Narrator-Kern: To their amazement, the antigen-bound particles worked just as well if not better than the apoptotic cell carriers. And, when they injected their particles intravenously into mice conditioned to develop an experimental form of MS, the vast majority of mice never developed it. They were also able to halt the progression of the disease by injecting the mice just after the first symptoms of MS emerged.
Narrator-Kern: Shea says one advantage of their particles is that they’re made from a substance that already has FDA approval
Shea: This particle has been used as biodegradable sutures for many years. The same material has been used in drug delivery microspheres for years. We’ve made them a different size, but ultimately the material is something that’s readily accepted by the body.
Narrator-Kern: Miller believes that the particles could be adapted to potentially treat a wide range of diseases and conditions involving the immune system:
Miller: We’ve also shown that these antigen-coupled nanoparticles can be used in animal models of allergic disease. We found in unpublished results that we can attach allergens onto these particles and inhibit the development of an allergic immune response. A third potential use for this, we’re envisioning being used to induce tolerance to to promote the acceptance of cell and tissue grafts between individuals.
Narrator-Kern: Shea points to the unique collaboration that lead to the successful development of these particles.
Shea: This is just a tremendous example of the opportunities of interdisciplinary work. My lab has the materials but we don’t have the biological expertise that Dr. Miller has. At the same time, he has tremendous biological expertise but necessarily didn’t have the tools by which to modify or create a particle of our own that would have all the properties we would want.
Narrator-Kern: Miller’s hopeful that years of manipulating the immune system in a lab environment might soon yield a treatment for patients.
Miller: I’ve been working in the field of immune tolerance my whole scientific career. It took 30 years to get from animal experiments to our initial phase 1 clinical trials using the antigen-coupled apoptotic cells. We’re hoping it only takes a year or two to get into the phase 1 clinical trial using the particles.
Nanoparticles Evade the Immune System
Researchers help nanoparticles carrying tumor-fighting drugs evade the immune system
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Introduction
This is a production of the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health.
Host-Margot Kern
Welcome to the NIBIB science highlights podcast. Nanoparticles are being used by researchers and most recently in clinical trials to ferry cancer-fighting drugs to tumors. The use of nanoparticles as a drug delivery mechanism could allow doctors to give patients higher doses of toxic medications while sparing healthy tissue. But the immune system poses a major obstacle to nanoparticle delivery. That’s because nanoparticles are viewed by immune cells as foreign bodies that should be eliminated.
I recently spoke with an NIBIB grantee, Dr. Dennis Discher, a molecular and cell biophysicist in Chemical and Biomolecular Engineering at the University of Pennsylvania. Discher published a paper in Science on Feberury 22, 2013 in which he describes a new method developed by his lab that helps nanoparticles escape attacks from cells of the immune system, specifically macrophages.
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Host-Margot Kern
Dr. Discher, for those of us who aren’t familiar with the biology of the immune system, what is a macrophage?
Interviewee-Dennis Discher
A macrophage is a giant (macro), phage or (phagos); it means eating in Greek. So it’s a giant eater. And, they’ll eat nanoparticles, they’ll eat microparticles, microbes, but even in implants, if you implant a giant object that’s much bigger than the size of the cell, these cells will try to eat it and in frustration they’ll start fusing and forming a giant multi-nucleated cell, a true giant macrophage. So often with particles in modern times or implants, we really don’t want this innate immune system to attack what it’s had eons to evolve its expertise to do.
Host-Margot Kern
In the Science paper you attached a protein called CD47 to particles and this prevented them from being recognized by macrophages as foreign. How was your attention first called to this particular protein?
Interviewee-Dennis Discher
So we, like many other people, in fact I would say most people, as we injected particles into the bloodstream in studies more than ten years ago, we’d find that too many of our particles were taken up by macrophages. And then a paper appeared in Science about thirteen years ago from a group in St. Louis that reported a mouse that has a specific protein on the surface of really all the cells. It’s a protein called CD47. They described it as a marker of self as passivating macrophages, as a protein that normally, on normal cells, limits macrophages from eating the cells, and when they knocked it out in a mouse, well they see macrophages in other mice eating cells taken from the mice that had the CD47 protein missing.
Host-Margot Kern
So then, what did your lab do with this new information regarding CD47?
Interviewee-Dennis Discher
There were clearly questions that arose. This was obviously a study in a knockout mouse that left us scratching our heads. And we really wanted to know, would this work on humans and would it work on our particles and maybe other types of materials. I mean macrophage interactions not only with particles but with everything we implant in the body.
Host-Margot Kern
So then how did your lab determine if human CD47 has the same function as mouse CD47?
Interviewee-Dennis Discher
We aimed to understand human CD47 on human cells starting with human blood cells because mouse blood cells is where this other paper from the St. Louis group had started. And we worked up to understanding the integration and the differences with mouse and then expressing the protein and showing that we could put human protein on a plastic microparticle and inhibit phagocytosis in a dish.
Host-Margot Kern
How then did your lab bring this to studies in animals?
Interviewee-Dennis Discher
About the same time that our paper appeared, a group in Toronto published that there was one strain of mouse and this NOD/SCID strain of mouse, human CD47 interacts with macrophages of that strain of mouse and no other strains of mice. The receptor is called SIRPα. (It doesn’t really matter.) But, you now have a mouse receptor compatible with human CD47 that prompted us together with additional information to really take this in vivo.
Host-Margot Kern
In the Science paper, you inject these NOD/SCID mice with nanoparticles that have human CD47 attached to them. But you don’t attach the full CD47 protein. Why?
Interviewee-Dennis Discher
Human CD47 is somewhat different within the population. The receptor, the SIRPα, is certainly different within the human population as it is within different strains of mice. So we studied a crystal structure of the two bonded together and realized that maybe we could minimize CD47 to a universal donor peptide. So we simulated it in a computer, showed that it would doc in silico, and then synthesized it, put it on particles, injected it in this NOD/SCID mouse, and showed ultimately that it was inhibiting uptake of our particles by macrophages.
Host-Margot Kern
Discher went on to report in the Science article that he was able to use his CD47-bound nanoparticles to deliver the anti-tumor drug paclitaxel to mice who had been given human-like tumors and that his particles were as good or better at shrinking the mice’s tumors as paclitaxel’s standard carrier, Cremophore, without causing any of the side effects.
For NIBIB News, I’m Margot Kern
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Ultrasound Patch Heals Venous Ulcers in Human Trial
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Introduction
This is a production of the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health.
Host: Margot Kern
Kern: Venous ulcers affect approximately 1% of the population. These chronic wounds occur when valves in the veins of the leg malfunction, and they can take months and occasionally years to heal.
Kern: Dr. Michael Weingarten, Chief of Drexel University’s vascular surgery department and a specialist in chronic wound management, says venous ulcers are a significant economic burden.
Weingarten: To put it in perspective, it’s a chronic problem accounting for probably several billion dollars in healthcare costs in the United States, and it’s prevalent not only in elderly patients but also in working age patients. So, we’re talking about expenses in terms of treating the wounds, but also time loss from work, disabilities, things like that.
Kern: Currently, the standard treatment for venous ulcers involves controlling swelling, taking care of the wound by keeping it moist and preventing infection, and a technique called compression therapy in which patients wear special socks that squeeze the leg to prevent blood from flowing backwards. But Dr. Weingarten says these measures are lacking.
Weingarten: These are what we call passive treatment modalities. We try to change the homeostasis of the wound so it’s ideal for healing and that can be very difficult. There are very few active technologies that actively stimulate healing for these ulcers, in particular.
Kern: But that may soon change. With support from NIBIB, a research team led by Dr. Peter A. Lewin, a professor of biomedical engineering at Drexel University, has recently created a novel battery operated ultrasound patch that can accelerate healing by delivering low-frequency, low-intensity ultrasound directly to wounds.
Kern: In a recent pilot clinical trial of twenty patients, the team reported that patients who received therapeutic ultrasound treatment using their patch, in addition to standard compression therapy, had a net reduction in wound size after just four weeks. In contrast, patients who received only compression therapy had an average increase in wound size at 4 weeks. Surprisingly, the greatest effect was seen in a subgroup of five patients who received the ultrasound treatment for the least amount of time (just 15 minutes per week) at the lowest frequency (20khZ). All five patients in this group experienced complete healing by the fourth week.
Kern: Dr. Weingarten was impressed by the results:
Weingarten: This is a very difficult population to heal in a timely manner, and so, yes, it was rather surprising.
Kern: While using ultrasound to accelerate wound healing is not a new idea, until now, it’s been difficult to prove its clinical efficacy. One reason is that studies have used a range of ultrasound frequencies, and it turns out that lower frequencies may be better at promoting healing. So says Peter Lewin.
Lewin: We had an idea that if some of the mechanisms which were proposed by us in the literature would work, they probably would be better or more profound if we applied them at the lower frequency. Typically the therapeutic ultrasound is applied at 1-3 megahertz, we went down to between approximately 20 and a 100 kilohertz. So it’s at least a magnitude of order lower.
Kern: The team’s clinical findings were supported by experiments conducted in the lab in which cells involved in wound healing were treated with low-frequency ultrasound. The team found that 15 minutes of 20khz stimulation caused both an increase in cell proliferation and cell metabolism just 24 hours after receiving the treatment.
Kern: According to the team, one of the most challenging but also important components of the research was developing the battery operated ultrasound patch. Lewin says the device offers tremendous value to patients because it gives them the option of receiving frequent treatments without having to return to the clinic, ultimately increasing patient compliance, while saving money.
Lewin: So the whole device is approximately a 100 grams and it’s connected to the fully wearable two batteries, which are fully rechargeable, so the patient can have the device on the wound, if needed, twenty four hours a day.
Kern: The team is now working to develop an additional component of their patch which would allow physicians to view subtle tissue changes during and directly after ultrasound treatment using near infrared spectroscopy.
Kern: Lewin says the ability to monitor changes in the wound tissue during treatment would allow physicians to optimize the frequency, intensity, and rate of the ultrasound delivery for each patient. Going forward, the team plans to test their patch on a larger group of patients and to expand their studies in the lab, examining different types of cells involved in wound healing.
Kern: Josh Samuels, a Ph.D. student in Lewin’s lab says some of these mechanistic studies are already under way.
Samuels: We’re looking now a lot more at the macrophages and we’re also looking at fibroblasts. We’re trying to look at the different levels of wound healing. We know there is the inflammation phase, the proliferation phase, and the remodeling and we’re looking at the primary participants at each phase. So we know the endothelial cells are going to play a big role and the macrophages. So we’re actually examining the effects of ultrasound on each individually and then we’re going to look collectively to see if there’s cascade effects, see if one influences the other. That’s really where we’re at now with our in vitro studies.
Kern: For NIBIB, I’m Margot Kern.
Sorting Circulating Tumor Cells
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Introduction
This is a production of the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health
Host: Margot Kern
Toner: The benefits of finding circulating tumor cells is multifold. It could really turn cancer into a manageable disease.
Kern: You’re listening to Mehmet Toner, a professor of biomedical engineering at Harvard University, who led the development of a microfluidic device that can isolate circulating tumor cells from whole blood samples.
Kern: Circulating tumor cells, also known as CTCs, are cells that have broken off a solid tumor and entered the blood stream. While most CTCs die in the blood, a small percentage can become embedded into tissues of distant organs where they can begin to form a new tumor. This is how cancer spreads or metastasizes.
Kern: But, despite their ill-effects, these cells have a silver lining. The presence of CTCs in the blood can actually help doctors monitor whether a particular treatment is working.
Toner: If the circulating tumor cell number goes up or down as the patients are on treatment, you would know very quickly from the blood test.
Kern: In addition to monitoring CTC number in the blood, the DNA of circulating tumor cells can be analyzed to look for cancer-causing mutations, information that can be used by doctors to determine what medications may be most effective.
Toner: Most drugs now, almost exclusively, all new drugs are based on targeted therapy where patients with specific mutations respond to specific treatments, targeted treatments, that are less toxic, much more effective.
Kern: The advantage of analyzing CTC DNA is that information about a specific tumor can be procured from the blood, thus, negating the need for a tissue biopsy, a procedure that can be extremely painful for some patients and difficult to carry out.
Toner: So you’re doing a liquid biopsy, in a sense. You find these cells in blood and then look at their genomic makeup and decide what drug they should be put on.
Kern: Sounds simple enough. Well, it would be if it weren’t for the fact that circulating tumor cells are nearly impossible to catch.
Toner: They are one in a billion, one in 10 billion, so it’s really looking for a needle in a haystack, if not worse.
Kern: To give you an idea of the size of this haystack, for every milliliter of blood, there are a few million white blood cells, around a billion red blood cells, and only between 1 and 10 circulating tumor cells. Those are pretty tough odds, but it turns out they’re not insurmountable.
Kern: Over the past several years, Toner has worked to develop a microfluidic chip that can separate the rare and valuable CTCs from the billions of other cells found in a patient’s blood.
Toner: The way we find these cells is when you go to a physician’s office, you give a tube of blood, that tube of blood goes through the chip. The chip has very precise flow conditions and this way we can very precisely and rapidly isolate those rare cells.
Kern: The CTC chip technology was initially developed with support from an NIBIB Quantum grant. They’re called quantum grants because the goal is to achieve a profound or quantum leap in healthcare. Toner says they’re making that leap:
Toner: We are developing a new technology that didn’t exist before. We are trying to understand the biology of these cells, because we know very little about these cells, and we are trying to identify and clinically validate applications, and that’s a pretty tall order, and it cannot be addressed by standard grant mechanisms. Quantum grants was the exact structure we were looking for.
Kern: Toner says the interdisciplinary nature of the project has been integral to its success, but also one of the most challenging aspects.
Toner: Our team has engineers, biologists and geneticists, and clinicians. The ability to pull a team like that together, getting everybody motivated, create the right incentives, and solve complex problems is really very difficult. I think that was the most difficult part, and it’s the part that requires a lot of attention, I call it social engineering. That’s the part that really fuels the entire enterprise
Kern: The beauty of the CTC chip says Toner is it wouldn’t place any additional burdens on the patient or physician.
Toner: It’s really taking the blood. We do that every day for millions of people. And instead of looking for X, Y, Z, now you’ll be looking for circulating tumor cells using this technology. So it really fits into the flow of physician-patient interaction very easily.
Kern: While not yet available clinically, nor a complete substitute for current cancer care, technology like Toner’s microfluidic CTC chip could someday make monitoring and treating cancer more manageable for clinicians and patients alike.
Toner: It will enable, in the long run, to treat the right patient with the right drug at right dose at the right time.
Kern: For NIBIB, I’m Margot Kern
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