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.
Could Your Probiotic Be Making You Sicker?
Mindy D. had suffered from constipation for years when her gastroenterologist advised her, at 38, to take a popular over-the-counter probiotic. Over the next two years, she experimented with different dosages, sometimes taking it three times a day. But she kept getting sicker—sometimes so ill she couldn't work.
"We shouldn't just presume probiotics are safe."
Her symptoms improved only after she traveled from Long Island to Georgia to see Satish S. C. Rao, a gastroenterologist at Augusta University. "The key thing was taking her off probiotics and treating her with antibiotics," he says.
That solution sounds bizarre, if, like many, you believe that antibiotics are bad and probiotics good. Millions of Americans take probiotics—live bacteria deemed useful—assuming there can be only positive effects. The truth is that you really don't know how any probiotic will affect you. To quote the American Gastroenterological Association Center for Gut Microbiome Research and Education, "It remains unclear what strains of bacteria at what dose by what route of administration are safe and effective for which patients."
"We shouldn't just presume probiotics are safe," says Purna Kashyap, a gastroenterologist from the Mayo Clinic, in Rochester, Minnesota, and a member of the Center's scientific advisory board. Neither the U.S. Food and Drug Administration or the European Food Safety Authority have approved probiotics as a medical treatment. Things can go very wrong in the ill: Among patients with severe acute pancreatitis, one study found that a dose of probiotics increased the chance of death. Even randomized controlled trials of probiotics rarely report harms adequately and the effect over the long-term has not been studied.
Many people pick up a product at a drug store or health store without ever telling a doctor. Doctors are fans, too: in a 2017 survey of healthcare providers at Stanford, more than 60 percent of the respondents said they prescribed probiotics. Many did so inconsistently, leaving the choice of which probiotic up to the patient. Healthy people take them for a range of unproven benefits, including protection from infections or heart disease or to sharpen their brains.
It's fine—unless it isn't. "Probiotics are capable of altering the microbiome in unpredictable ways," explains Leo Galland, an internist in New York who specializes in difficult digestions. "I've had patients who got gas and bloating, constipation or diarrhea from probiotics."
Your Microbiome Is Unique
The booming probiotic market has fed on excitement about the new science of the microbiome, the genetic material of all the microbes that live in our bodies and on our skin. Microbes make up 1 to 3 percent of every human being's body mass—you carry trillions of them, including more than a hundred species and thousands of strains. To identify a microbe, you need to know the genus, species and strain. For example, in Lactobacillus rhamnosus GG, the ingredient in the OTC probiotic Culturelle, Lactobacillus is the genus, rhamnosus is the species and GG is the strain designation.
Variations in your microbiome could help explain why you put on weight or suffer from Crohn's or depression. Each of us has our own unique mix.
A decade ago, the U.S. National Institute of Health (NIH) launched the Microbiome Project to establish a baseline description of health. Scientists sequenced the DNA in more than 2,200 strains, still a small fraction of the whole.
Within a couple of years, we had evidence that our microbiomes are distinctive. Another team used the NIH data set to look into the idea of microbial "fingerprints." A classic computer science algorithm allowed it to assign individuals "codes" defined by DNA sequences of their microbes—no human DNA required. Using information solely from the guts, "Eighty percent of individuals could still be uniquely identified up to a year later," they wrote.
That distinctiveness makes a difference when we try to change our mix by swallowing bacteria considered "pro." Even in healthy people, the reactions to probiotics vary widely, according to a study in Cell in September. The team examined the intestines of healthy volunteers who had taken a cocktail of eleven strains of probiotics for the experiment. Which took up residence in the intestinal lining? The answer depended on the person. Led by Eran Segal and colleagues at the Weizmann Institute of Science, in Rehovot, Israel, the authors concluded that effective supplements would have to be personalized.
Patients with "brain fog" improved dramatically when they were taken off their probiotics and given antibiotics as well.
To truly customize a probiotic, however, we'd have to know the state of an individual's gut microbiome, identify danger signs and link them to symptoms, isolate relevant strains of probiotics that might be needed, and get them into the gut lining effectively. Commercial tests are still at step one. Several companies claim to assess your microbiome based on a stool sample—but the Weizmann team has also shown that the differences between our gut linings aren't apparent from our stool. Galland has explored testing his patients looking for ways to help. "I've concluded that uBiome, American Gut Project, and others don't yield useful information," he observes.
Can A Probiotic Make Your Brain Foggy?
Besides taking her probiotic, Mindy D. had cut out gluten and upped her vegetables and fruits. But soon after she ate her seemingly healthy meals, she would begin to feel dizzy and sometimes even slurred her words, as if she were drunk. "It was such an intense feeling," she said.
A slender 5 ft. 2 inches, she dropped 20 pounds, becoming unhealthily thin. She traveled to see specialists in Minnesota and Connecticut and took two month-long medical leaves before she found Rao in Georgia.
In June, Rao created a stir when he and his coauthors reported that a cluster of his patients with "brain fog"—the "intense feeling" Mindy D. described—improved dramatically when they were taken off their probiotics and given antibiotics as well.
His idea was that lactobacilli and other bacteria colonized their small intestines, rather than making it to the colon as intended—a condition known as "small intestinal bacteria overgrowth" (SIB0) that some gastroenterologists treat with antibiotics. In this group, he argues, the small intestine produced the brain fog symptoms as a consequence of D-lactic acidosis, a phenomenon usually associated with damaged intestines. "If you have brain fogginess along with gas and bloating, please don't take probiotics," Rao says.
The paper prompted a rebuttal at the end of September from Eamonn Quigley, a gastroenterologist at Houston Methodist, who criticized the methodology in detail. Kashyap, of the Mayo Clinic, is skeptical as well. "People were picked for their brain fogginess and they were taking probiotics. Probiotics could be an innocent bystander," he says.
"It's hard for me to imagine the mechanism of say, Culturelle, causing SIB0," says Shira Doron, a specialist in infectious diseases and associate professor at Tufts University School of Medicine who studies probiotics. "The vast majority of people will never suffer a side effect from a probiotic. But probiotics are a live organism so they have a unique set of potential risks that other supplements don't have. They can give you a severe infection in very rare circumstances."
The larger point is that probiotics should be used under a doctor's care. In April, a panel of 14 experts on behalf of the European Society for Primary Care Gastroenterology concluded that "specific probiotics are beneficial in certain lower GI problems." That does not mean any over-the-counter probiotic is likely to help you because it helped your cousin.
"Even your doctor may be going by anecdotal experience, rather than hard science."
Both Galland and Rao use probiotics in their practice, but carefully. "We advise caution against excessive and indiscriminate use of probiotics especially without a well-defined medical indication, and particularly in patients with gastrointestinal dysmotility," when the muscles of the digestive system don't work normally, Rao's team wrote.
"Because there are so many studies out there that are poorly done, that aren't looking at side effects, the science is murky. Even your doctor may be going by anecdotal experience, rather than hard science," Doron adds. Your doctor may tell you that many of his patients report a great experience with probiotics. As Doron points out, however, with disorders like irritable bowel syndrome, the most common gastrointestinal diagnosis, the placebo effect is very strong. Many patients could "respond to anything if they believe it works," she says.
Advances Bring First True Hope to Spinal Cord Injury Patients
Seven years ago, mountain biking near his home in Whitefish, Montana, Jeff Marquis felt confident enough to try for a jump he usually avoided. But he hesitated just a bit as he was going over. Instead of catching air, Marquis crashed.
Researchers' major new insight is that recovery is still possible, even years after an injury.
After 18 days on a ventilator in intensive care and two-and-a-half months in a rehabilitation hospital, Marquis was able to move his arms and wrists, but not his fingers or anything below his chest. Still, he was determined to remain as independent as possible. "I wasn't real interested in having people take care of me," says Marquis, now 35. So, he dedicated the energy he formerly spent biking, kayaking, and snowboarding toward recovering his own mobility.
For generations, those like Marquis with severe spinal cord injuries dreamt of standing and walking again – with no realistic hope of achieving these dreams. But now, a handful of people with such injuries, including Marquis, have stood on their own and begun to learn to take steps again. "I'm always trying to improve the situation but I'm happy with where I'm at," Marquis says.
The recovery Marquis and a few of his fellow patients have achieved proves that our decades-old understanding of the spinal cord was wrong. Researchers' major new insight is that recovery is still possible, even years after an injury. Only a few thousand nerve cells actually die when the spinal cord is injured. The other neurons still have the ability to generate signals and movement on their own, says Susan Harkema, co-principal investigator at the Kentucky Spinal Cord Injury Research Center, where Marquis is being treated.
"The spinal cord has much more responsibility for executing movement than we thought before," Harkema says. "Successful movement can happen without those connections from the brain." Nerve cell circuits remaining after the injury can control movement, she says, but leaving people sitting in a wheelchair doesn't activate those sensory circuits. "When you sit down, you lose all the sensory information. The whole circuitry starts discombobulating."
Harkema and others use a two-pronged approach – both physical rehabilitation and electrical stimulation – to get those spinal cord circuits back into a functioning state. Several research groups are still honing this approach, but a few patients have already taken steps under their own power, and others, like Marquis, can now stand unassisted – both of which were merely fantasies for spinal cord injury patients just five years ago.
"This really does represent a leap forward in terms of how we think about the capacity of the spinal cord to be repaired after injury," says Susan Howley, executive vice president for research for the Christopher & Dana Reeve Foundation, which supports research for spinal cord injuries.
Jeff Marquis biking on a rock before his accident.
This new biological understanding suggests the need for a wholesale change in how people are treated after a spinal cord injury, Howley says. But today, most insurance companies cover just 30-40 outpatient rehabilitation sessions per year, whether you've sprained your ankle or severed your spinal cord. To deliver the kind of therapy that really makes a difference for spinal cord injury patients requires "60-80-90 or 150 sessions," she says, adding that she thinks insurance companies will more than make up for the cost of those therapy sessions if spinal cord injury patients are healthier. Early evidence suggests that getting people back on their feet helps prevent medical problems common among paralyzed people, including urinary tract infections, which can require costly hospital stays.
"Exercise and the ability to fully bear one's own weight are as crucial for people who live with paralysis as they are for able-bodied people," Howley notes, adding that the Reeve Foundation is now trying to expand the network of facilities available in local communities to offer this essential rehabilitation.
"Providing the right kind of training every day to people could really improve their opportunity to recover," Harkema says.
It's not entirely clear yet how far someone could progress with rehabilitation alone, Harkema says, but probably the best results for someone with a severe injury will also require so-called epidural electrical stimulation. This device, implanted in the lower back for a cost of about $30,000, sends an electrical current at varying frequencies and intensities to the spinal cord. Several separate teams of researchers have now shown that epidural stimulation can help restore sensation and movement to people who have been paralyzed for years.
Epidural stimulation boosts the electrical signal that is generated below the point of injury, says Daniel Lu, an associate professor and vice chair of neurosurgery at the UCLA School of Medicine. Before a spinal cord injury, he says, a neuron might send a message at a volume of 10 but after injury, that volume might drop to a two or three. The epidural stimulation potentially trains the neuron to respond to the lower volume, Lu says.
Lu has used such stimulators to improve hand function – "essentially what defines us" – in two patients with spinal cord injuries. Both increased their grip strength so they now can lift a cup to drink by themselves, which they couldn't do before. He's also used non-invasive stimulation to help restore bladder function, which he says many spinal cord injury patients care about as much as walking again.
A closeup of the stimulator.
Not everyone will benefit from these treatments. People whose injury was caused by a cut to the spinal cord, as with a knife or bullet, probably can't be helped, Lu says, adding that they account for less than 5 percent of spinal cord injuries.
The current challenge Lu says is not how to stimulate the spinal cord, but where to stimulate it and the frequency of stimulation that will be most effective for each patient. Right now, doctors use an off-the-shelf stimulator that is used to treat pain and is not optimized for spinal cord patients, Harkema says.
Swiss researchers have shown impressive results from intermittent rather than continuous epidural stimulation. These pulses better reflect the way the brain sends its messages, according to Gregoire Courtine, the senior author on a pair of papers published Nov. 1 in Nature and Nature Neuroscience. He showed that he could get people up and moving within just a few days of turning on the stimulation. Three of his patients are walking again with only a walker or minimal assistance, and they also gained voluntary leg movements even when the stimulator was off. Continuous stimulation, this research shows, actually interferes with the patients' perception of limb position, and thus makes it harder for them to relearn to walk.
Even short of walking, proper physical rehabilitation and electrical stimulation can transform the quality of life of people with spinal cord injury, Howley and Harkema say. Patients don't need to be able to reach the top shelf or run a marathon to feel like they've been "cured" from their paralysis. Instead, recovering bowel, bladder and sexual functions, the ability to regulate their temperature and blood pressure, and reducing the breakdown of skin that can lead to a life-threatening infection can all be transformative – and all appear to improve with the combination of rehabilitation and electrical stimulation.
Howley cites a video of one of Harkema's patients, Stefanie Putnam, who was passing out five to six times a day because her blood pressure was so low. She couldn't be left alone, which meant she had no independence. After several months of rehabilitation and stimulation, she can now sit up for long periods, be left alone, and even, she says gleefully, cook her own dinner. "Every time I watch it, it brings me to tears," Howley says of the video. "She's able to resume her normal life activity. It's mind-boggling."
The work also suggests a transformation in the care of people immediately after injury. They should be allowed to stand and start taking steps as soon as possible, even if they cannot do it under their own power, Harkema says. Research is also likely to show that quickly implanting a stimulator after an injury will make a difference, she says.
There may be medications that can help immediately after an injury, too. One drug currently being studied, called riluzole, has already been approved for ALS and might help limit the damage of a spinal cord injury, Howley says. But testing its effectiveness has been a slow process, she says, because it needs to be given within 12 hours of the initial injury and not enough people get to the testing sites in time.
Stem cell therapy also offers promise for spinal cord injury patients, Howley says – but not the treatments currently provided by commercial stem cell clinics both in the U.S. and overseas, which she says are a sham. Instead, she is carefully following research by a California-based company called Asterias Biotherapeutics, which announced plans Nov. 8 to merge with a company called BioTime.
Asterias and a predecessor company have been treating people since 2010 in an effort to regrow nerves in the spinal cord. All those treated have safely tolerated the cells, but not everyone has seen a huge improvement, says Edward Wirth, who has led the trial work and is Asterias' chief medical director. He says he thinks he knows what's held back those who didn't improve much, and hopes to address those issues in the next 3- to 4-year-long trial, which he's now discussing with the U.S. Food and Drug Administration.
So far, he says, some patients have had an almost complete return of movement in their hands and arms, but little improvement in their legs. The stem cells seem to stimulate tissue repair and regeneration, he says, but only around the level of the injury in the spinal cord and a bit below. The legs, he says, are too far away to benefit.
Wirth says he thinks a combination of treatments – stem cells, electrical stimulation, rehabilitation, and improved care immediately after an injury – will likely produce the best results.
While there's still a long way to go to scale these advances to help the majority of the 300,000 spinal cord injury patients in the U.S., they now have something that's long been elusive: hope.
"Two or three decades ago there was no hope at all," Howley says. "We've come a long way."