New Hope for Organ Transplantation: Life Without Anti-Rejection Drugs
Rob Waddell dreaded getting a kidney transplant. He suffers from a genetic condition called polycystic kidney disease that causes the uncontrolled growth of cysts that gradually choke off kidney function. The inherited defect has haunted his family for generations, killing his great grandmother, grandmother, and numerous cousins, aunts and uncles.
But he saw how difficult it was for his mother and sister, who also suffer from this condition, to live with the side effects of the drugs they needed to take to prevent organ rejection, which can cause diabetes, high blood pressure and cancer, and even kidney failure because of their toxicity. Many of his relatives followed the same course, says Waddell: "They were all on dialysis, then a transplant and ended up usually dying from cancers caused by the medications."
When the Louisville native and father of four hit 40, his kidneys barely functioned and the only alternative was either a transplant or the slow death of dialysis. But in 2009, when Waddell heard about an experimental procedure that could eliminate the need for taking antirejection drugs, he jumped at the chance to be their first patient. Devised by scientists at the University of Louisville and Northwestern University, the innovative approach entails mixing stem cells from the live kidney donor with that of the recipient to create a hybrid immune system, known as a chimera, that would trick the immune system and prevent it from attacking the implanted kidney.
The procedure itself was done at Northwestern Memorial Hospital in Chicago, using a live kidney donated by a neighbor of Waddell's, who camped out in Chicago during his recovery. Prior to surgery, Waddell underwent a conditioning treatment that consisted of low dose radiation and chemotherapy to weaken his own immune system and make room for the infusion of stem cells.
"The low intensity chemo and radiation conditioning regimen create just enough space for the donor stem cells to gain a foothold in the bone marrow and the donor's immune system takes over," says Dr. Joseph Levanthal, the transplant surgeon who performed the operation and director of kidney and pancreas transplantation at Northwestern University Feinberg School of Medicine. "That way the recipient develops an immune system that doesn't see the donor organ as foreign."
"As a surgeon, I saw what my patients had to go through—taking 25 pills a day, dying at an early age from heart disease, or having a 35% chance of dying every year on dialysis."
A week later, Waddell had the kidney transplant. The following day, he was infused with a complex cellular cocktail that included blood-forming stem cells derived from his donor's bone marrow mixed what are called tolerance inducing facilitator cells (FCs); these cells help the foreign stem cells get established in the recipient's bone marrow.
Over the course of the following year, he was slowly weaned off of antirejection medications—a precaution in case the procedure didn't work—and remarkably, hasn't needed them since. "I felt better than I had in decades because my kidneys [had been] degrading," recalls Waddell, now 54 and a CPA for a global beverage company. And what's even better is that this new approach offers hope for one of his sons who has also inherited the disorder.
Kidney transplants are the most frequent organ transplants in the world and more than 23,000 of these procedures were done in the United States in 2019, according to the United Network for Organ Sharing. Of this, about 7,000 operations are done annually using live organ donors; the remainder use organs from people who are deceased. Right now, this revolutionary new approach—as well as a similar strategy formulated by Stanford University scientists--is in the final phase of clinical trials. Ultimately, this research may pave the way towards realizing the holy grail of organ transplantation: preventing organ rejection by creating a tolerant state in which the recipient's immune system is compatible with the donor, which would eliminate the need for a lifetime of medications.
"As a surgeon, I saw what my patients had to go through—taking 25 pills a day, dying at an early age from heart disease, or having a 35% chance of dying every year on dialysis," says Dr. Suzanne Ildstad, a transplant surgeon and director of the Institute for Cellular Therapeutics at the University of Louisville, whose discovery of facilitator cells were the basis for this therapeutic platform. Ildstad, who has spent more than two decades searching for a better way, says, "This is something I have worked for my entire life."
The Louisville group uses a combination of chemo and radiation to replace the recipient's immune and blood forming cells with that of the donor. In contrast, the Stanford protocol involves harvesting the donor's blood stem cells and T-cells, which are the foot soldiers of the immune system that fight off infections and would normally orchestrate the rejection of the transplanted organ. Their transplant recipients undergo a milder form of "conditioning" that only radiates discrete parts of the body and selectively targets the recipient's T-cells, creating room for both sets of T-cells, a strategy these researchers believe has a better safety profile and less of a chance of rejection.
"We try to achieve immune tolerance by a true chimerism," says Dr. Samuel Strober, a professor of medicine for immunology and rheumatology at Stanford University and a leader of this research team. "The recipients immune system cells are maintained but mixed in the blood with that of the donor."
Studies suggest both approaches work. In a 2018 clinical trial conducted by Talaris Therapeutics, a Louisville-based biotech founded by Ildstad, 26 of 37 (70%) of the live donor kidney transplant recipients no longer need immunosuppressants. Last fall, Talaris began the final phase of clinical tests that will eventually encompass more than 120 such patients.
The Stanford group's cell-based immunotherapy, which is called MDR-101 and is sponsored by the South San Francisco biotech, Medeor Therapeutics, has had similar results in patients who received organs from live donors who were either well matched, such as one from siblings, meaning they were immunologically identical, or partially matched; Talaris uses unrelated donors where there is only a partial match.
In their 2020 clinical trial of 51 patients, 29 were fully matched and 22 were a partial match; 22 of the fully matched recipients didn't need antirejection drugs and ten of the partial matches were able to stop taking some of these medications without rejection. "With our fully matched, roughly 80% have been completely off drugs up to 14 years later," says Strober, "and reducing the number of drugs from three to one [in the partial matches] means you have far fewer side effects. The goal is to get them off of all drugs."
But these protocols are limited to a small number of patients—living donor kidney recipients. As a consequence, both teams are experimenting with ways to broaden their approach so they can use cadaver organs from deceased donors, with human tests planned in the coming year. Here's how that would work: after the other organs are removed from a deceased donor, stem cells are harvested from the donor's vertebrae in the spinal column and then frozen for storage.
"We do the transplant and give the patient a chance to recover and maintain them on drugs," says Ildstad. "Then we do the tolerance conditioning at a later stage."
If this strategy is successful, it would be a genuine game changer, and open the door to using these protocols for transplanting other cadaver organs, including the heart, lungs and liver. While the overall procedure is complex and costly, in the long run it's less expensive than repeated transplant surgeries, the cost of medications and hospitalizations for complications caused by the drugs, or thrice weekly dialysis treatments, says Ildstad.
And she adds, you can't put a price tag on the vast improvement in quality of life.
The Women of RNA: Two Award-Winners Share Why They Spent Their Careers Studying DNA's Lesser-Known Cousin
When Lynne Maquat, who leads the Center for RNA Biology at the University of Rochester, became interested in the ribonucleic acid molecule in the 1970s, she was definitely in the minority. The same was true for Joan Steitz, now professor of molecular biophysics and biochemistry at Yale University, who began to study RNA a decade earlier in the 1960s.
"My first RNA experiment was a failure, because we didn't understand how things worked," Steitz recalls. In her first undergraduate experiment, she unwittingly used a lab preparation that destroyed the RNA. "Unknowingly, our preparation contained enzymes that degraded our RNA."
At the time, scientists pursuing genetic research tended to focus on DNA, or deoxyribonucleic acid — and for good reason. It was clear that the enigmatic double-helix ribbon held the answers to organisms' heredity, genetic traits, development, growth and aging. If scientists could decipher the secrets of DNA and understand how its genetic instructions translate into the body's functions in health and disease, they could develop treatments for all kinds of diseases. On the contrary, the prevailing dogma of the time viewed RNA as merely a helper that passively carried out DNA's genetic instructions for protein-making — so it received much less attention.
But Maquat and Steitz weren't interested in heredity. They studied biochemistry and biophysics, so they wanted to understand how RNA functioned on the molecular level — how it carried instructions, catalyzed reactions, and helped build protein bonds, among other things.
"I'm a mechanistic biochemist, so I like to know how things happen," Maquat says. "Once you understand the mechanism, you can think of how to solve problems." And so the quest to understand how RNA does its job became the focus of both women's careers.
"People can now appreciate why some of us studied RNA for such a long time."
Half a century later, in 2021, their RNA work has earned two prestigious recognitions only months from each other. In February, they received the Wolf Prize in Medicine, followed by the Warren Alpert Foundation Prize in May, awarded to scientists whose achievements led to prevention, cure or treatments of human diseases.
It was the development of the COVID-19 vaccines that made RNA a household name. Made by Moderna and Pfizer, the vaccines use the RNA molecule to deliver genetic instructions for making SARS-CoV-2's characteristic spike protein in our cells. The presence of this foreign-looking protein triggers the immune system to attack and remember the pathogen. As the vaccines reached the finish line, RNA took center stage, and it was Maquat's and Steitz's research that helped reveal how these molecular cogwheels drive many biological functions within cells.
If you think of a cell as a kingdom, the DNA plays the role of a queen. Like a monarch in a palace, DNA nestles inside the cell's nucleus issuing instructions needed for the cell to function. But no queen can successfully govern without her court, her messengers, and her soldiers, as well as other players that make her kingdom work. That's what RNAs do — they act as the DNA's vassals. They carry instructions for protein assembly, catalyze reactions and supervise many other processes to make sure the cellular kingdom performs as it should.
There are a myriad of these RNA vassals in our cells, and each type has its own specific task. There are messenger RNAs that deliver genetic instructions for protein synthesis from DNA to ribosomes, the cells' protein-making factories. There are ribosomal RNAs that help stitch together amino acids to make proteins. There are transfer RNAs that can bring amino acids to this protein synthesis machine, keeping it going. Then there are circular RNAs that act as sponges, absorbing proteins to help regulate the activity of genes. And that's only the tip of the iceberg when it comes to RNA diversity, researchers say.
"We know what the most abundant and important RNAs are doing," says Steitz. "But there are thousands of different ones, and we still don't have a full knowledge of them."
Critical to RNA's proper functioning is a process called splicing, in which a precursor mRNA is transformed into mature, fully-functional mRNA — a phenomenon that Steitz's work helped elucidate. The splicing process, which takes place in cellular assembly lines, involves removing extra RNA sequences and stringing the remaining RNA pieces together. Steitz found that tiny RNA particles called snRNPs are crucial to this process. They act as handy helpers, finding and removing errant genetic material from the mRNA molecules.
A dysfunctional RNA assembly line leads to diseases, including many cancers. For instance, Steitz found that people with Lupus — an autoimmune disorder — have antibodies that mistakenly attack the little snRNP helpers. She also discovered that when snRNPs don't do their job properly, they can cause what scientists call mis-splicing, producing defective mRNAs.
Fortunately, cells have a built-in quality-control process that can spot and correct these mistakes, which is what Maquat studied in her work. In 1981, she discovered a molecular quality-control system that spots and destroys such incorrectly assembled mRNA. With the cryptic name "nonsense-mediated mRNA decay" or NMD, this process is vital to the health and wellbeing of a cellular kingdom in humans — because splicing mistakes happen far more often than one would imagine.
"We estimate that about a third of our mRNA are mistakes," Maquat says. "And nonsense-mediated mRNA decay cleans up these mistakes." When this quality-control system malfunctions, defective mRNA forge faulty proteins, which mess up the cellular machinery and cause disease, including various forms of cancer.
Scientists' newfound appreciation of RNA opens door to many novel treatments.
Now that the first RNA-based shots were approved, the same principle can be used for create vaccines for other diseases, the two RNA researchers say. Moreover, the molecule has an even greater potential — it can serve as a therapeutic target for other disorders. For example, Spinraza, a groundbreaking drug approved in 2016 for spinal muscular atrophy, uses small snippets of synthetic genetic material that bind to the RNA, helping fix splicing errors. "People can now appreciate why some of us studied RNA for such a long time," says Maquat.
Steitz is thrilled that the entire field of RNA research is enjoying the limelight. "I'm delighted because the prize is more of a recognition of the field than just our work," she says. "This is a more general acknowledgment of how basic research can have a remarkable impact on human health."
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
In 2010, a 67-year-old former executive assistant for a Fortune 500 company was diagnosed with mild cognitive impairment. By 2014, her doctors confirmed she had Alzheimer's disease.
As her disease progressed, she continued to live independently but wasn't able to drive anymore. Today, she can manage most of her everyday tasks, but her two daughters are considering a live-in caregiver. Despite her condition, the woman may represent a beacon of hope for the approximately 44 million people worldwide living with Alzheimer's disease. The now 74-year-old is among a small cadre of Alzheimer's patients who have undergone an experimental ultrasound procedure aimed at slowing cognitive decline.
In November 2020, Elisa Konofagou, a professor of biomedical engineering and director of the Ultrasound and Elasticity Imaging Laboratory at Columbia University, and her team used ultrasound to noninvasively open the woman's blood-brain barrier. This barrier is a highly selective membrane of cells that prevents toxins and pathogens from entering the brain while allowing vital nutrients to pass through. This regulatory function means the blood-brain barrier filters out most drugs, making treating Alzheimer's and other brain diseases a challenge.
Ultrasound uses high-frequency sound waves to produce live images from the inside of the human body. But scientists think it could also be used to boost the effectiveness of Alzheimer's drugs, or potentially even improve brain function in dementia patients without the use of drugs.
The procedure, which involves a portable ultrasound system, is the culmination of 17 years of lab work. As part of a small clinical trial, scientists positioned a sensor transmitting ultrasound waves on top of the woman's head while she sat in a chair. The sensor sends ultrasound pulses throughout the target region. Meanwhile, investigators intravenously infused microbubbles into the woman to boost the effects of the ultrasound. Three days after the procedure, scientists scanned her brain so that they could measure the effects of the treatments. Five months later, they took more images of her brain to see if the effects of the treatment lasted.
Promising Signs
After the first brain scan, Konofagou and her team found that amyloid-beta, the protein that clumps together in the brains of Alzheimer's patients and disrupts cell function, had declined by 14%. At the woman's second scan, amyloid levels were still lower than before the experimental treatment, but only by 10% this time. Konofagou thinks repeat ultrasound treatments given early on in the development of Alzheimer's may have the best chance at keeping amyloid plaques at bay.
This reduction in amyloid appeared to halt the woman's cognitive decline, at least temporarily. Following the ultrasound treatment, the woman took a 30-point test used to measure cognitive impairment in Alzheimer's. Her score — 22, indicating mild cognitive impairment — remained the same as before the intervention. Konofagou says this was actually a good sign.
"Typically, every six months an Alzheimer's patient scores two to three points lower, so this is highly encouraging," she says.
Konofagou speculates that the results might have been even more impressive had they applied the ultrasound on a larger section of the brain at a higher frequency. The selected site was just 4 cubic centimeters. Current safety protocols set by the U.S. Food and Drug Administration stipulate that investigators conducting such trials only treat one brain region with the lowest pressure possible.
The Columbia trial is aided by microbubble technology. During the procedure, investigators infused tiny, gas-filled spheres into the woman's veins to enhance the ultrasound reflection of the sound waves.
The big promise of ultrasound is that it could eventually make drugs for Alzheimer's obsolete.
"Ultrasound with microbubbles wakes up immune cells that go on to discard amyloid-beta," Konofagou says. "In this way, we can recover the function of brain neurons, which are destroyed by Alzheimer's in a sort of domino effect." What's more, a drug delivered alongside ultrasound can penetrate the brain at a dose up to 10 times higher.
Costas Arvanitis, an assistant professor at Georgia Institute of Technology who studies ultrasonic biophysics and isn't involved in the Columbia trial, is excited about the research. "First, by applying ultrasound you can make larger drugs — picture an antibody — available to the brain," he says. Then, you can use ultrasound to improve the therapeutic index, or the ratio of the effectiveness of a drug versus the ratio of adverse effects. "Some drugs might be effective but because we have to provide them in high doses to see significant responses they tend to come with side effects. By improving locally the concentration of a drug, you open up the possibility to reduce the dose."
The Columbia trial will enroll just six patients and is designed to test the feasibility and safety of the approach, not its efficacy. Still, Arvantis is hopeful about the potential benefits of the technique. "The technology has already been demonstrated to be safe, its components are now tuned to the needs of this specific application, and it's safe to say it's only a matter of time before we are able to develop personalized treatments," he says.
Konofagou and her colleagues recently presented their findings at the 20th Annual International Symposium for Therapeutic Ultrasound and intend to publish them in a scientific journal later this year. They plan to recruit more participants for larger trials, which will determine how effective the therapy is at improving memory and brain function in Alzheimer's patients. They're also in talks with pharmaceutical companies about ways to use their therapeutic approach to improve current drugs or even "create new drugs," says Konofagou.
A New Treatment Approach
On June 7, the FDA approved the first Alzheimer's disease drug in nearly two decades. Aducanumab, a drug developed by Biogen, is an antibody designed to target and reduce amyloid plaques. The drug has already sparked immense enthusiasm — and controversy. Proponents say the drug is a much-needed start in the fight against the disease, but others argue that the drug doesn't substantially improve cognition. They say the approval could open the door to the FDA greenlighting more Alzheimer's drugs that don't have a clear benefit, giving false hope to both patients and their families.
Konofagou's ultrasound approach could potentially boost the effects of drugs like aducanumab. "Our technique can be seamlessly combined with aducanumab in early Alzheimer's, where it has shown the most promise, to further enhance both its amyloid load reduction and further reduce cognitive deficits while using exactly the same drug regimen otherwise," she says. For the Columbia team, the goal is to use ultrasound to maximize the effects of aducanumab, as they've done with other drugs in animal studies.
But Konofagou's approach could transcend drug controversies, and even drugs altogether. The big promise of ultrasound is that it could eventually make drugs for Alzheimer's obsolete.
"There are already indications that the immune system is alerted each time ultrasound is exerted on the brain or when the brain barrier is being penetrated and gets activated, which on its own may have sufficient therapeutic effects," says Konofagou. Her team is now working with psychiatrists in hopes of using brain stimulation to treat patients with depression.
The potential to modulate the brain without drugs is huge and untapped, says Kim Butts Pauly, a professor of radiology, electrical engineering and bioengineering at Stanford University, who's not involved in the Columbia study. But she admits that scientists don't know how to fully control ultrasound in the brain yet. "We're only at the starting point of getting the tools to understand and harness how ultrasound microbubbles stimulate an immune response in the brain."
Meanwhile, the 74-year-old woman who received the ultrasound treatment last year, goes on about her life, having "both good days and bad days," her youngest daughter says. COVID-19's isolation took a toll on her, but both she and her daughters remain grateful for the opportunity to participate in the ultrasound trial.
"My mother wants to help, if not for herself, then for those who will follow her," the daughter says. She hopes her mother will be able to join the next phase of the trial, which will involve a drug in conjunction with the ultrasound treatment. "This may be the combination where the magic will happen," her daughter says.