In the old days, Greek physicians would perform autopsies to figure out how their patients got sick. Later, with the discovery of microscope and x-ray technologies, scientists would study live cells to understand what’s happening inside the human body. And now, with one of the most incredible breakthroughs of the 21st century, the Human Genome Project has completely transformed the field of medicine.
Scientists and physicians can now sequence and compare patients’ data to identify anomalies or mutations with the entire human genome mapping. This information allows them to make an early diagnosis and helps them take proactive measures by predicting who is more at risk of acquiring certain illnesses. But while a human’s DNA codes for all the genes inside the body, it’s not enough to decide which functions are normal and which are impaired. More surprisingly, all the cells in your body, whether from the liver or the skin, have the same genomic content. But then, what makes their function so vastly different from one another?
The answer to this is gene expression. This biological phenomenon is a process that allows specific genes in your cells to get activated, so they can make proteins and perform their particular function. It’s the basis of cell variation and is how all body organs work differently. Without protein synthesis, your body can’t make essential components like hormones or enzymes that regulate respiration, digestion, and growth, among other processes. Therefore, your cells must make specific proteins whenever needed for normal physiological functioning.
Gene expression isn’t just crucial for deciding which processes must occur. In contrast, it also plays a vital role in inhibiting reactions not required by the cell or those that may harm the body. Scientists are now using the Mammalian CHO Expression system to gain a deeper understanding of human physiology and learn about a particular protein.
Although gene expression applications in modern medicine are vast, we discuss the top five most beneficial ones below.
1. Monoclonal antibody production2
Perhaps the most widely used application of gene expression systems today is in the production of monoclonal antibodies. These are biological molecules designed and produced in a laboratory to substitute or enhance antibodies in a living cell. Through the process of manipulating and genetically engineering the gene expressions of immune cells, scientists can increase the subsequent yield of antibodies. Using mammalian cell lines often gives the most efficient results for the commercial production of these therapeutic proteins.
This application primarily benefits old-age patients, those fighting cancer, or individuals with severely compromised immune systems. By restoring, modifying, and mimicking the body’s natural immunity patterns, monoclonal antibodies can help them fight infection better than their innate cells.
2. Disease biomarkers
A biomarker refers to any biological parameter or molecule you can quantify in a laboratory and link to a particular disease or condition. Once specified, this helps make a quick and precise diagnosis, allowing patients to get more immediate treatments. One of the most effective ways to quantify a biomolecule is by studying its gene expression or measuring it using quantitative PCR techniques. By identifying changes in gene expression, scientists can relate how a synthesis or inhibition of a protein can result in a medical condition. Moreover, doctors can predict a cutoff value for classifying disease severity depending on how much or how little the gene gets expressed in a patient’s cell. This approach is especially beneficial for cancer patients as it assists oncologists in providing a more accurate prognosis.
3. Gene function
In genetic engineering, the development of knockout techniques proved useful in studying the role of particular genes. Scientists did this by employing two primary approaches: forward and reverse genetics. For the forward approach, their goal was to identify the genetic etiology of a disease. For this reason, they would select a group of patients diagnosed with the same illness and sequence their DNA. If there were any alterations from regular gene expression, that specific gene would then get linked to the disease.
In contrast, the reverse genetics approach first manipulates the gene expression in a living cell and then studies its consequent effect. For example, a researcher may completely “silence” or block a gene’s expression, thereby inhibiting its protein synthesis. If this gene were responsible for producing a growth hormone, then it would impede the growth of that individual. And thus, scientists will be able to identify the function of this gene.
Besides genetic manipulation, the cell’s external cues can alter its gene expression. For instance, if a cell is present in an energy-rich environment, it will inhibit the expression of the gene responsible for metabolizing food.
4. Commercial production of insulin
According to a recent study, the global burden of type 1 diabetes (T1D) in 2021 was around 8.4 million. Since T1D is insulin-dependent, patients with this disease need at least two or three insulin shots per day. And since it’s a chronic illness with no known cure, this dependency lasts for a lifetime. Therefore, the demand for therapeutic insulin is exceptionally high. To meet this demand and ensure a broader demographic of patients can afford insulin shots, genetic engineers began the synthesis of insulin by modifying bacterial cells. After cloning the human insulin gene and enhancing its expression, it gets infected into a bacteria. When this bacteria replicates, it produces insulin and other genes in its genome. Pharmaceutical companies then isolate and purify this insulin to make it broadly available for diabetic patients worldwide.
5. Drug discovery
Most medications and drug therapies used to treat cancer patients are nonspecific and cytotoxic. These drugs also kill normal body cells besides cancer cells, resulting in the patient’s hair and weight loss. But thanks to new research and genomic technology, pharmaceutical companies are now targeting specific molecular pathways where a drug can be most effective. By measuring a cell’s gene expression in a clinical trial, they compare it with a placebo group to identify any adverse reactions beforehand. Since this approach only allows the drug to act on a particular region, as opposed to the entire cell, it lowers the side effects of chemotherapy.
Besides being more effective, studying gene expression for drug discovery is more cost-effective and has fewer ethical concerns. Instead of recruiting subjects in clinical trials and putting them at risk of potential harm, researchers can use mammalian cell lines to identify preliminary results.
Using gene expression applications in medicine has facilitated several downstream processes in the healthcare industry. Therapeutic production of antibodies and other biomolecules is now much more accessible, quicker, efficient, and cost-effective. And this is only the beginning, with scientists having only scratched the surface. As more discoveries and knowledge come to light, the healthcare field can open doors to many avenues that were once unapproachable.