Introduction
Red blood cells (RBCs), also known as erythrocytes, are the most abundant type of cell in the human body's blood. The blood comprises 45 percent of RBCs, less than one percent of white blood cells and platelets, and 55 percent of plasma. RBCs are primarily responsible for transporting oxygen to the cells of all body parts and delivering carbon dioxide back from cells to the lungs. They contain hemoglobin, a protein that is responsible for carrying oxygen. These cells are derived from stem cells in the red bone marrow and have a life of approximately 120 days. Red blood cell formation takes about two days, and the human body forms nearly two million RBCs every second. In recent studies, physicians have found that RBCs can act as potential drug carriers apart from exhibiting their normal function. Such modified RBCs are said to help curb the incidence of antibiotic resistance. This article discusses the need for such engineered RBCs, what they do, and how they work.
What Are Smart RBCs?
Researchers and scientists identified a natural delivery system that can safely carry antibiotics throughout the body to selectively attack and kill bacteria using red blood cells as a carrier. They modified and tested red blood cells as potential drug carriers. Hence, smart red blood cells are engineered cells modified to deliver drugs, especially antibiotics, to selectively target bacteria without harming healthy cells. Smart RBCs not only target bacteria without affecting other parts of the body but also potentially alleviate the side effects associated with antibiotics. Traditional drug therapies have multiple challenges, such as a tendency to degrade rapidly when they enter the blood circulation system; and are also randomly distributed throughout the body. Hence, people often take higher or repeated doses, increasing both exposure to the drug and the risk of side effects. Smart RBCs help offset the drug’s harmful effects and only target specific bacteria without harming the body. The scientific community has studied the efficacy of RBCs as possible drug carriers for the last few decades.
How Do Smart RBCs Work?
Scientists have developed a way to open red blood cells and completely remove all the inner components, leaving behind only a membrane called a liposome. The red blood cell is loaded with drug molecules before being injected into the human body. The procedure also involves the step in which the outside of the red blood cell membrane is coated with antibiotics to allow it to stick to bacteria and deliver the antibody safely. The antibiotics are concealed inside the red blood cells, so they do not interact with or harm the healthy cells as they pass through the body. These red blood cells are designed only to target the bacteria that must be targeted. These cells, modified as ‘super-human’ versions, circulate in the body for several weeks, searching for their target bacteria or tumors and distributing drugs accordingly.
This technology combines biological and synthetic materials to form a new structure to solve the problem of plagued delivery systems, especially those that use a synthetic molecule that has been rejected by the body or has failed to reach the target. Only red blood cells were focused for this work as they are sturdy, stable, most abundant, biocompatible, affordable, and have a long natural lifespan of approximately 120 days, giving them enough time to reach different target sites. Also, their shape and lack of organelles imply that their inner volume and surface could be easily used to carry a range of drug molecules.
What Are the Indications of Smart RBCs?
Smart RBCs are believed to help curb the resistant infections on the rise. Antibiotic resistance is emerging as a major public health concern. It occurs when the bacteria develop the ability to defeat antibiotics (medicines that fight bacterial infections). The antibiotic resistance crisis is mostly attributed to the misuse and overuse of antibiotics and the lack of development of new drugs.
Over the years, the bacterial population has undergone multiple mutations (changes) to evolve and develop a better defense against drugs. They are rightly called ‘superbugs’ as they remain unaffected by the drugs designed to kill them. Approximately seven hundred thousand people are estimated to lose their lives due to antibiotic-resistant infections. These numbers are expected to increase to ten million by 2050. The fact that antibiotics constitute routine treatment nowadays increases this problem as greater bacterial resistance results in most drugs being ineffective, resulting in several negative implications for public health. Antibiotics that still can work against them are highly harmful and toxic, causing dangerous side effects. Scientists believe RBCs as drug carriers can help utilize the few resistance-proof antibiotics left to treat bacterial infections.
Smart RBCs are particularly used to fight dangerous and often drug-resistant bacteria like Escherichia coli (E. coli) that can cause serious infections such as gastroenteritis (also known as stomach flu; this infection is characterized by cramps, diarrhea, nausea, fever, and vomiting), pneumonia (lung infection causing lung tissues to swell) and bloodstream infections. Researchers used RBCs as natural drug carriers for the world’s only remaining antibiotic, Polymyxin B (PmB), which is still successful in defeating ‘superbugs.’ PmB is the last resort treatment to destroy E. coli bacteria. Researchers modified and tested RBCs for this drug due to its high toxicity and harmful side effects, including kidney damage.
Conclusion
RBCs are blood cells with the primary function of gas exchange at the cellular level. But studies have been done to modify these cells to act as natural drug delivery systems working to help curb the antibiotic resistance crisis. They are believed to attack specific bacteria and not harm healthy cells. Scientists believe that this technology will allow for the distribution of potent drugs for the treatment of Alzheimer’s, drug-resistant bacteria, and cancer as well. Further studies are going on to apply this technology to deliver drugs across the blood-brain barrier to effectively and quickly treat patients with depression. However, the efficacy of these smart RBCs and their additional application is still under research.
