Philip Felgner left and Robert Malone. He fell out with his supervisor, Salk gene-therapy researcher Inder Verma and, in , left graduate studies early to work for Felgner at Vical, a recently formed start-up in San Diego, California. There, they and collaborators at the University of Wisconsin—Madison showed that the lipid—mRNA complexes could spur protein production in mice 7. Malone and his Vical coworkers also explored using mRNA for vaccines: their early patent filings describe injecting mRNA coding for HIV proteins into mice, and observing some protection against infection, although not the production of specific immune cells or molecules; this work was never published in a peer-reviewed journal.
Credit: Robert Malone. Then things got messy. Malone contends that Verma and Vical struck a back-room deal so that the relevant intellectual property went to Vical.
Malone was listed as one inventor among several, but he no longer stood to profit personally from subsequent licensing deals, as he would have from any Salk-issued patents. Verma resigned from the Salk in , following allegations of sexual harassment, which he continues to deny. He completed medical school and did a year of clinical training before working in academia, where he tried to continue research on mRNA vaccines but struggled to secure funding.
In , for example, he unsuccessfully applied to a California state research agency for money to develop a mRNA vaccine to combat seasonal coronavirus infections. Malone focused on DNA vaccines and delivery technologies instead. In , he moved into commercial work and consulting.
And in the past few months, he has started publicly attacking the safety of the mRNA vaccines that his research helped to enable. Merck scientists evaluated the mRNA technology in mice with the aim of creating an influenza vaccine, but then abandoned that approach.
There, in , a team led by Pierre Meulien, working with industrial and academic partners, was the first to show that an mRNA in a liposome could elicit a specific antiviral immune response in mice 8. Another exciting advance had come in , when scientists at the Scripps Research Institute in La Jolla used mRNA to replace a deficient protein in rats, to treat a metabolic disorder 9.
But it would take almost two decades before independent labs reported similar success. Pierre Meulien. The DNA platform ultimately yielded a few licensed vaccines for veterinary applications — helping, for example, to prevent infections in fish farms.
But for reasons that are not completely understood, DNA vaccines have been slow to find success in people. In the s and for most of the s, nearly every vaccine company that considered working on mRNA opted to invest its resources elsewhere. The conventional wisdom held that mRNA was too prone to degradation, and its production too expensive. The mRNA vaccine idea had a more favourable reception in oncology circles, albeit as a therapeutic agent, rather than to prevent disease.
Beginning with the work of gene therapist David Curiel, several academic scientists and start-up companies explored whether mRNA could be used to combat cancer. If mRNA encoded proteins expressed by cancer cells, the thinking went, then injecting it into the body might train the immune system to attack those cells. Another cancer immunologist had more success, which led to the founding of the first mRNA therapeutics company, in Eli Gilboa proposed taking immune cells from the blood, and coaxing them to take up synthetic mRNA that encoded tumour proteins.
The cells would then be injected back into the body where they could marshal the immune system to attack lurking tumours. The approach was looking promising until a few years ago, when a late-stage candidate vaccine failed in a large trial; it has now largely fallen out of fashion. Hoerr was the first to achieve success. But few scientists or investors seemed interested.
Eventually, money trickled in. And within a few years, human testing began. A more formal trial, involving tumour-specific mRNA for people with skin cancer, kicked off soon after. They plugged away at the technology for many years, working at Johannes Gutenberg University Mainz in Germany, earning patents, papers and research grants, before pitching a commercial plan to billionaire investors in In , after repeated rejections, she was given the choice of leaving UPenn or accepting a demotion and pay cut.
In , she began working with Weissman, who had just started a lab at UPenn. She and Weissman soon worked out why: the synthetic mRNA was arousing 16 a series of immune sensors known as Toll-like receptors, which act as first responders to danger signals from pathogens. Credit: Penn Medicine.
Few scientists at the time recognized the therapeutic value of these modified nucleotides. But the scientific world soon awoke to their potential.
The finding made a splash. He co-founded a start-up, Moderna in Cambridge. But it was too late. In February , it granted exclusive patent rights to a small lab-reagents supplier in Madison. RNA-based vaccines rely on the human body to do the trick of making the harmless viral protein, and many scientists hope they could be the answer to stamping out the current spread of COVID around the world.
Smita Nair , PhD, professor of surgery, came to Duke in to study cancer therapeutics as a post-doctoral researcher in the lab of Eli Galboa, PhD, now a professor at the University of Miami.
In , Nair and her colleague David Boczkowski made a fortuitous discovery in the lab. For years, they had been experimenting with creating a cell-based vaccine to treat cancer, treating human immune cells with various lab-grown proteins in hit-or-miss fashion to see if they could train the immune system to recognize cancer and kill it. Amused, Nair tried treating the immune cells with the contents of the new tube, which turned out to be tumor-derived RNA.
After exposure to the tumor-derived RNA, the immune system recognized the actual tumor cells and began to fight them off as well. The successful experiment was revolutionary for cancer therapy. Nair and Boczkowski published the finding in the Journal of Experimental Medicine in , and the company Argos Technology developed the technology and currently has two products in clinical trials.
These building blocks of protein are assembled by cellular organelles called ribosomes, comprised of ribosomal RNA rRNA and proteins. In recent years, other functions for RNA have been discovered. RNA also helps regulate various cellular processes from cell division and growth to ageing and death.
And RNA can even act as an enzyme, speeding up various biochemical reactions within the cell. This approach has several advantages. Secondly, mRNA is directly translated in the cytoplasm. The use of mRNA bypasses this step, resulting in a quicker onset of gene editing.
Thirdly, as guide RNA and Cas9 mRNA are both single-stranded, they can be encapsulated in a single nanoparticle, ensuring the delivery of both components into the target cells.
Therefore, the mRNA platform can address the limitations of gene editing approaches Xiong et al. Antibodies are the tailored molecules produced by the immune cells to fight pathogens.
Antibodies are composed of four chains: two light chains and two heavy chains. These peptide chains are modified and linked together via disulfide bonds. For antibody production, eukaryotic cells are necessary, as prokaryotic cells cannot glycosylate the peptide chains.
This production method, however, is very expensive. To enable cost-effective expression, some researchers have produced single-chain variable antibody fragments in E. These fragments preserved the essential characteristics of antibodies. Unfortunately, their serum half-life is very short. Antibody mRNA could be a much more suitable and cost-effective alternative.
The antibodies are then produced as long as the self-amplifying mRNA is present in the body, providing long-term expression up to 6 weeks of specific antibodies Brito et al. Untreated, it takes the body several days or even weeks to produce antibodies.
However, in the case of venom or toxin, an immediate neutralising response is paramount. Antibodies that neutralise toxins are produced by using mammalian cell cultures; a very expensive and less accessible system. Since the mRNA needs to be taken up and expressed by the immune cells immediately, much attention has been given to the type of mRNA vaccine used, administration route and delivery format naked, carrier mediated, cell based.
They reported that the first strong signal of mRNA in the lymphoid node was observed after 4 hours as a result of intramuscular administration Lindsay et al. This approach has been utilised to treat respiratory syncytial virus, hepatitis A, hepatitis B, cytomegalovirus, and measles.
However, in some patients, equine sera horse-derived sera can cause a hypersensitivity reaction. In the search for more efficient antibody production systems, much work was concentrated on producing monoclonal antibodies mAbs in the s. Also, no animals are involved in the production of mAbs. However, the development and manufacturing of mAbs is costly, and a very high titre of antibodies is required to treat or protect against infectious diseases. A new strategy includes the administration of mAb-encoding mRNA.
Additionally, some antibodies are specific to both T cells and cancer cells, known as bispecific antibodies. They bring T cells and cancer cells in close proximity and induce the T cells to kill the cancer cells. However, there are some limitations of mAbs application. They have a short serum half-life, especially bispecific antibodies. In addition, there are manufacturing issues, including reduced stability, and a tendency of mAbs to aggregate.
Impurities can also accumulate during the production process. All these limitations can be addressed by direct application of mRNA encoding for mAbs Stadler et al. They are part of the post-transcriptional machinery in the cell.
In this way, gene expression in a cell can be controlled at a post-transcriptional level. This approach is used to develop treatments for HIV, cancer and melanoma.
The fascinating dream of RNA therapeutics has transitioned to practical reality. In the future, RNA holds the potential to disrupt the field of biopharmaceuticals, vaccine development, cell reprogramming, RNA interference and much more. Are you working on a mRNA application? Eurofins Genomics can support your research from start to end. Our comprehensive product and service portfolio includes:. Did you like this article on mRNA in biology? Then subscribe to our Newsletter and we will keep you informed about our next blog posts.
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