Convalescent plasma – first used to treat diphtheria in 1890 – has been dusted off the shelf to treat COVID-19. Does it work? Should we rely strictly on the altruism of donors or should people be paid for it?
The biologic theory is that a person who has recovered from a disease has chemicals in their blood, most likely antibodies, that contributed to their recovery, and transferring those to a person who is sick might aid their recovery. Whole blood won't work because there are too few antibodies in a single unit of blood and the body can hold only so much of it.
Plasma comprises about 55 percent of whole blood and is what's left once you take out the red blood cells that carry oxygen and the white blood cells of the immune system. Most of it is water but the rest is a complex mix of fats, salts, signaling molecules and proteins produced by the immune system, including antibodies.
A process called apheresis circulates the donors' blood through a machine that separates out the desired parts of blood and returns the rest to the donor. It takes several times the length of a regular whole blood donation to cycle through enough blood for the process. The end product is a yellowish concentration called convalescent plasma.
It was used extensively during the great influenza epidemic off 1918 but fell out of favor with the development of antibiotics. Still, whenever a new disease emerges – SARS, MERS, Ebola, even antibiotic-resistant bacteria – doctors turn to convalescent plasma, often as a stopgap until more effective antibiotic and antiviral drugs are developed. The process is certainly safe when standard procedures for handling blood products are followed, and historically it does seem to be beneficial in at least some patients if administered early enough in the disease.
With few good treatment options for COVID-19, doctors have given convalescent plasma to more than a hundred thousand Americans and tens of thousand of people elsewhere, to mixed results. Placebo-controlled trials could give a clearer picture of plasma's value but it is difficult to enroll patients facing possible death when the flip of a coin will determine who will receive a saline solution or plasma.
And the plasma itself isn't some uniform pill stamped out in a factory, it's a natural product that is shaped by the immune history of the donor's body and its encounter not just with SARS-CoV-2 but a lifetime of exposure to different pathogens.
Researchers believe antibodies in plasma are a key factor in directly fighting the virus. But the variety and quantity of antibodies vary from donor to donor, and even over time from the same donor because once the immune system has cleared the virus from the body, it stops putting out antibodies to fight the virus. Often the quality and quantity of antibodies being given to a patient are not measured, making it somewhat hit or miss, which is why several companies have recently developed monoclonal antibodies, a single type of antibody found in blood that is effective against SARS-CoV-2 and that is multiplied in the lab for use as therapy.
Plasma may also contain other unknown factors that contribute to fighting disease, say perhaps signaling molecules that affect gene expression, which might affect the movement of immune cells, their production of antiviral molecules, or the regulation of inflammation. The complexity and lack of standardization makes it difficult to evaluate what might be working or not with a convalescent plasma treatment. Thus researchers are left with few clues about how to make it more effective.
Many Americans living along the border with Mexico regularly head south to purchase prescription drugs at a significant discount. Less known is the medical traffic the other way, Mexicans who regularly head north to be paid for plasma donations, which are prohibited in their country; the U.S. allows payment for plasma donations but not whole blood. A typical payment is about $35 for a donation but the sudden demand for convalescent plasma from people who have recovered from COVID-19 commands a premium price, sometimes as high as $200. These donors are part of a fast-growing plasma industry that surpassed $25 billion in 2018. The U.S. supplies about three-quarters of the world's needs for plasma.
Payment for whole blood donation in the U.S. is prohibited, and while payment for plasma is allowed, there is a stigma attached to payment and much plasma is donated for free.
The pharmaceutical industry has shied away from natural products they cannot patent but they have identified simpler components from plasma, such as clotting factors and immunoglobulins, that have been turned into useful drugs from this raw material of plasma. While some companies have retooled to provide convalescent plasma to treat COVID-19, often paying those donors who have recovered a premium of several times the normal rate, most convalescent plasma has come as donations through traditional blood centers.
In April the Mayo Clinic, in cooperation with the FDA, created an expanded access program for convalescent plasma to treat COVID-19. It was meant to reduce the paperwork associated with gaining access to a treatment not yet approved by the FDA for that disease. Initially it was supposed to be for 5000 units but it quickly grew to more than twenty times that size. Michael Joyner, the head of the program, discussed that experience in an extended interview in September.
The Centers for Medicare and Medicaid Services (CMS) also created associated reimbursement codes, which became permanent in August.
Mayo published an analysis of the first 35,000 patients as a preprint in August. It concluded, "The relationships between mortality and both time to plasma transfusion, and antibody levels provide a signature that is consistent with efficacy for the use of convalescent plasma in the treatment of hospitalized COVID-19 patients."
It seemed to work best when given early in infection and in larger doses; a similar pattern has been seen in studies of monoclonal antibodies. A revised version will soon be published in a major medical journal. Some criticized the findings as not being from a randomized clinical trial.
Convalescent plasma is not the only intervention that seems to work better when used earlier in the course of disease. Recently the pharmaceutical company Eli Lilly stopped a clinical trial of a monoclonal antibody in hospitalized COVID-19 patients when it became apparent it wasn't helping. It is continuing trials for patients who are less sick and begin treatment earlier, as well as in persons who have been exposed to the virus but not yet diagnosed as infected, to see if it might prevent infection. In November the FDA eased access to this drug outside of clinical trials, though it is not yet approved for sale.
Show Me the Money
The antibodies that seem to give plasma its curative powers are fragile proteins that the body produces to fight the virus. Production shuts down once the virus is cleared and the remaining antibodies survive only for a few weeks before the levels fade. [Vaccines are used to train immune cells to produce antibodies and other defenses to respond to exposure to future pathogens.] So they can be usefully harvested from a recovered patient for only a few short weeks or months before they decline precipitously. The question becomes, how does one mobilize this resource in that short window of opportunity?
The program run by the Mayo Clinic explains the process and criteria for donating convalescent plasma for COVID-19, as well as links to local blood centers equipped to handle those free donations. Commercial plasma centers also are advertising and paying for donations.
A majority of countries prohibit paying donors for blood or blood products, including India. But an investigation by India Today touted a black market of people willing to donate convalescent plasma for the equivalent of several hundred dollars. Officials vowed to prosecute, saying donations should be selfless.
But that enforcement threat seemed to be undercut when the health minister of the state of Assam declared "plasma donors will get preference in several government schemes including the government job interview." It appeared to be a form of compensation that far surpassed simple cash.
The small city of Rexburg, Idaho, with a population a bit over 50,000, overwhelmingly Mormon and home to a campus of Brigham Young University, at one point had one of the highest per capita rates of COVID-19 in the current wave of infection. Rumors circulated that some students were intentionally trying to become infected so they could later sell their plasma for top dollar, potentially as much as $200 a visit.
Troubled university officials investigated the allegations but could come up with nothing definitive; how does one prove intentionality with such an omnipresent yet elusive virus? They chalked it up to idle chatter, perhaps an urban legend, which might be associated with alcohol use on some other campus.
Doctors, hospitals, and drug companies are all rightly praised for their altruism in the fight against COVID-19, but they also get paid. Payment for whole blood donation in the U.S. is prohibited, and while payment for plasma is allowed, there is a stigma attached to payment and much plasma is donated for free. "Why do we expect the donors [of convalescent plasma] to be the only uncompensated people in the process? It really makes no sense," argues Mark Yarborough, an ethicist at the UC Davis School of Medicine in Sacramento.
"When I was in grad school, two of my closest friends, at least once a week they went and gave plasma. That was their weekend spending money," Yarborough recalls. He says upper and middle-income people may have the luxury of donating blood products but prohibiting people from selling their plasma is a bit paternalistic and doesn't do anything to improve the economic status of poor people.
"Asking people to dedicate two hours a week for an entire year in exchange for cookies and milk is demonstrably asking too much," says Peter Jaworski, an ethicist who teaches at Georgetown University.
He notes that companies that pay plasma donors have much lower total costs than do operations that rely solely on uncompensated donations. The companies have to spend less to recruit and retain donors because they increase payments to encourage regular repeat donations. They are able to more rationally schedule visits to maximize use of expensive apheresis equipment and medical personnel used for the collection.
It seems that COVID-19 has been with us forever, but in reality it is less than a year. We have learned much over that short time, can now better manage the disease, and have lower mortality rates to prove it. Just how much convalescent plasma may have contributed to that remains an open question. Access to vaccines is months away for many people, and even then some people will continue to get sick. Given the lack of proven treatments, it makes sense to keep plasma as part of the mix, and not close the door to any legitimate means to obtain it.
In December 1958, on a vacation with his wife in Kenya, a 28-year-old British tea broker named Robin Cavendish became suddenly ill. Neither he nor his wife Diana knew it at the time, but Robin's illness would change the course of medical history forever.
Robin was rushed to a nearby hospital in Kenya where the medical staff delivered the crushing news: Robin had contracted polio, and the paralysis creeping up his body was almost certainly permanent. The doctors placed Robin on a ventilator through a tracheotomy in his neck, as the paralysis from his polio infection had rendered him unable to breathe on his own – and going off the average life expectancy at the time, they gave him only three months to live. Robin and Diana (who was pregnant at the time with their first child, Jonathan) flew back to England so he could be admitted to a hospital. They mentally prepared to wait out Robin's final days.
But Robin did something unexpected when he returned to the UK – just one of many things that would astonish doctors over the next several years: He survived. Diana gave birth to Jonathan in February 1959 and continued to visit Robin regularly in the hospital with the baby. Despite doctors warning that he would soon succumb to his illness, Robin kept living.
After a year in the hospital, Diana suggested something radical: She wanted Robin to leave the hospital and live at home in South Oxfordshire for as long as he possibly could, with her as his nurse. At the time, this suggestion was unheard of. People like Robin who depended on machinery to keep them breathing had only ever lived inside hospital walls, as the prevailing belief was that the machinery needed to keep them alive was too complicated for laypeople to operate. But Diana and Robin were up for the challenges – and the risks. Because his ventilator ran on electricity, if the house were to unexpectedly lose power, Diana would either need to restore power quickly or hand-pump air into his lungs to keep him alive.
Robin's wheelchair was not only the first of its kind; it became the model for the respiratory wheelchairs that people still use today.
In an interview as an adult, Jonathan Cavendish reflected on his parents' decision to live outside the hospital on a ventilator: "My father's mantra was quality of life," he explained. "He could have stayed in the hospital, but he didn't think that was as good of a life as he could manage. He would rather be two minutes away from death and living a full life."
After a few years of living at home, however, Robin became tired of being confined to his bed. He longed to sit outside, to visit friends, to travel – but had no way of doing so without his ventilator. So together with his friend Teddy Hall, a professor and engineer at Oxford University, the two collaborated in 1962 to create an entirely new invention: a battery-operated wheelchair prototype with a ventilator built in. With this, Robin could now venture outside the house – and soon the Cavendish family became famous for taking vacations. It was something that, by all accounts, had never been done before by someone who was ventilator-dependent. Robin and Hall also designed a van so that the wheelchair could be plugged in and powered during travel. Jonathan Cavendish later recalled a particular family vacation that nearly ended in disaster when the van broke down outside of Barcelona, Spain:
"My poor old uncle [plugged] my father's chair into the wrong socket," Cavendish later recalled, causing the electricity to short. "There was fire and smoke, and both the van and the chair ground to a halt." Johnathan, who was eight or nine at the time, his mother, and his uncle took turns hand-pumping Robin's ventilator by the roadside for the next thirty-six hours, waiting for Professor Hall to arrive in town and repair the van. Rather than being panicked, the Cavendishes managed to turn the vigil into a party. Townspeople came to greet them, bringing food and music, and a local priest even stopped by to give his blessing.
Robin had become a pioneer, showing the world that a person with severe disabilities could still have mobility, access, and a fuller quality of life than anyone had imagined. His mission, along with Hall's, then became gifting this independence to others like himself. Robin and Hall raised money – first from the Ernest Kleinwort Charitable Trust, and then from the British Department of Health – to fund more ventilator chairs, which were then manufactured by Hall's company, Littlemore Scientific Engineering, and given to fellow patients who wanted to live full lives at home. Robin and Hall used themselves as guinea pigs, testing out different models of the chairs and collaborating with scientists to create other devices for those with disabilities. One invention, called the Possum, allowed paraplegics to control things like the telephone and television set with just a nod of the head. Robin's wheelchair was not only the first of its kind; it became the model for the respiratory wheelchairs that people still use today.
Robin went on to enjoy a long and happy life with his family at their house in South Oxfordshire, surrounded by friends who would later attest to his "down-to-earth" personality, his sense of humor, and his "irresistible" charm. When he died peacefully at his home in 1994 at age 64, he was considered the world's oldest-living person who used a ventilator outside the hospital – breaking yet another barrier for what medical science thought was possible.
Sarah Watts is a health and science writer based in Chicago. Follow her on Twitter at @swattswrites.
In June 2012, Kirstie Ennis was six months into her second deployment to Afghanistan and recently promoted to sergeant. The helicopter gunner and seven others were three hours into a routine mission of combat resupplies and troop transport when their CH-53D helicopter went down hard.
Miraculously, all eight people onboard survived, but Ennis' injuries were many and severe. She had a torn rotator cuff, torn labrum, crushed cervical discs, facial fractures, deep lacerations and traumatic brain injury. Despite a severely fractured ankle, doctors managed to save her foot, for a while at least.
In November 2015, after three years of constant pain and too many surgeries to count, Ennis relented. She elected to undergo a lower leg amputation but only after she completed the 1,000-mile, 72-day Walking with the Wounded journey across the UK.
On Veteran's Day of that year, on the other side of the country, orthopedic surgeon Cato Laurencin announced a moonshot challenge he was setting out to achieve on behalf of wounded warriors like Ennis: the Hartford Engineering A Limb (HEAL) Project.
Laurencin, who is a University of Connecticut professor of chemical, materials and biomedical engineering, teamed up with experts in tissue bioengineering and regenerative medicine from Harvard, Columbia, UC Irvine and SASTRA University in India. Laurencin and his colleagues at the Connecticut Convergence Institute for Translation in Regenerative Engineering made a bold commitment to regenerate an entire limb within 15 years – by the year 2030.
Dr. Cato Laurencin pictured in his office at UConn.
Photo Credit: UConn
Regenerative Engineering -- A Whole New Field
Limb regeneration in humans has been a medical and scientific fascination for decades, with little to show for the effort. However, Laurencin believes that if we are to reach the next level of 21st century medical advances, this puzzle must be solved.
An estimated 185,000 people undergo upper or lower limb amputation every year. Despite the significant advances in electromechanical prosthetics, these individuals still lack the ability to perform complex functions such as sensation for tactile input, normal gait and movement feedback. As far as Laurencin is concerned, the only clinical answer that makes sense is to regenerate a whole functional limb.
Laurencin feels other regeneration efforts were hampered by their siloed research methods with chemists, surgeons, engineers all working separately. Success, he argues, requires a paradigm shift to a trans-disciplinary approach that brings together cutting-edge technologies from disparate fields such as biology, material sciences, physical, chemical and engineering sciences.
As the only surgeon ever inducted into the academies of Science, Medicine and Innovation, Laurencin is uniquely suited for the challenge. He is regarded as the founder of Regenerative Engineering, defined as the convergence of advanced materials sciences, stem cell sciences, physics, developmental biology and clinical translation for the regeneration of complex tissues and organ systems.
But none of this is achievable without early clinician participation across scientific fields to develop new technologies and a deeper understanding of how to harness the body's innate regenerative capabilities. "When I perform a surgical procedure or something is torn or needs to be repaired, I count on the body being involved in regenerating tissue," he says. "So, understanding how the body works to regenerate itself and harnessing that ability is an important factor for the regeneration process."
The Birth of the Vision
Laurencin's passion for regeneration began when he was a sports medicine fellow at Cornell University Medical Center in the early 1990s. There he saw a significant number of injuries to the anterior cruciate ligament (ACL), the major ligament that stabilizes the knee. He believed he could develop a better way to address those injuries using biomaterials to regenerate the ligament. He sketched out a preliminary drawing on a napkin one night over dinner. He has spent the next 30 years regenerating tissues, including the patented L-C ligament.
As chair of Orthopaedic Surgery at the University of Virginia during the peak of the wars in Iraq and Afghanistan, Laurencin treated military personnel who survived because of improved helmets, body armor and battlefield medicine but were left with more devastating injuries, including traumatic brain injuries and limb loss.
"I was so honored to care for them and I so admired their steadfast courage that I became determined to do something big for them," says Laurencin.
When he tells people about his plans to regrow a limb, he gets a lot of eye rolls, which he finds amusing but not discouraging. Growing bone cells was relatively new when he was first focused on regenerating bone in 1987 at MIT; in 2007 he was well on his way to regenerating ligaments at UVA when many still doubted that ligaments could even be reconstructed. He and his team have already regenerated torn rotator cuff tendons and ACL ligaments using a nano-textured fabric seeded with stem cells.
Even as a finalist for the $4 million NIH Pioneer Award for high-risk/high-reward research, he faced a skeptical scientific audience in 2014. "They said, 'Well what do you plan to do?' I said 'I plan to regenerate a whole limb in people.' There was a lot of incredulousness. They stared at me and asked a lot of questions. About three days later, I received probably the best score I've ever gotten on an NIH grant."
In the Thick of the Science
Humans are born with regenerative abilities--two-year-olds have regrown fingertips--but lose that ability with age. Salamanders are the only vertebrates that can regenerate lost body parts as adults; axolotl, the rare Mexican salamander, can grow extra limbs.
The axolotl is important as a model organism because it is a four-footed vertebrate with a similar body plan to humans. Mapping the axolotl genome in 2018 enhanced scientists' genetic understanding of their evolution, development, and regeneration. Being easy to breed in captivity allowed the HEAL team to closely study these amphibians and discover a new cell type they believe may shed light on how to mimic the process in humans.
"Whenever limb regeneration takes place in the salamander, there is a huge amount of something called heparan sulfate around that area," explains Laurencin. "We thought, 'What if this heparan sulfate is the key ingredient to allowing regeneration to take place?' We found these groups of cells that were interspersed in tissues during the time of regeneration that seemed to have connections to each other that expressed this heparan sulfate."
Called GRID (Groups that are Regenerative, Interspersed and Dendritic), these cells were also recently discovered in mice. While GRID cells don't regenerate as well in mice as in salamanders, finding them in mammals was significant.
"If they're found in mice. we might be able to find these in humans in some form," Laurencin says. "We think maybe it will help us figure out regeneration or we can create cells that mimic what grid cells do and create an artificial grid cell."
What Comes Next?
Laurencin and his team have individually engineered and made every single tissue in the lower limb, including bone, cartilage, ligament, skin, nerve, blood vessels. Regenerating joints and joint tissue is the next big mile marker, which Laurencin sees as essential to regenerating a limb that functions and performs in the way he envisions.
"Using stem cells and amnion tissue, we can regenerate joints that are damaged, and have severe arthritis," he says. "We're making progress on all fronts, and making discoveries we believe are going to be helping people along the way."
That focus and advancement is vital to Ennis. After laboring over the decision to have her leg amputated below the knee, she contracted MRSA two weeks post-surgery. In less than a month, she went from a below-the-knee-amputee to a through-the-knee amputee to an above-the-knee amputee.
"A below-the-knee amputation is night-and-day from above-the-knee," she said. "You have to relearn everything. You're basically a toddler."
Kirstie Ennis pictured in July 2020.
Photo Credit: Ennis' Instagram
The clock is ticking on the timeline Laurencin set for himself. Nine years might seem like forever if you're doing time but it might appear fleeting when you're trying to create something that's never been done before. But Laurencin isn't worried. He's convinced time is on his side.
"Every week, I receive an email or a call from someone, maybe a mother whose child has lost a finger or I'm in communication with a disabled American veteran who wants to know how the progress is going. That energizes me to continue to work hard to try to create these sorts of solutions because we're talking about people and their lives."
He devotes about 60 hours a week to the project and the roughly 100 students, faculty and staff who make up the HEAL team at the Convergence Institute seem acutely aware of what's at stake and appear equally dedicated.
"We're in the thick of the science in terms of making this happen," says Laurencin. "We've moved from making the impossible possible to making the possible a reality. That's what science is all about."