Understanding the Impact of COVID-19 on the Lungs
The novel coronavirus can be frightening due to its rapid spread and its ability to infect seemingly healthy people. However, for most patients, the symptoms will be relatively mild. They are usually limited to a fever and a dry cough, although patients do report a wide range of other symptoms that vary from case to case. Most people will recover from COVID-19 within two weeks or so, but some are at a much higher risk of experiencing severe symptoms, and even death in some cases. The reason for this is the way that COVID-19 affects the lungs.
How Does COVID-19 Affect the Lungs?
While those with mild symptoms may assume that the virus is “not all that serious”, the truth is that COVID-19 can be deadly, particularly for those with a higher risk, particularly those with lung diseases, compromised immune systems, and the elderly.
The American Lung Association reports that
“Like the seasonal flu, older adults and those with chronic lung disease like asthma, COPD, and lung cancer are more at risk for severe symptoms. For these individuals especially, it is vital to heed public health warnings on social distancing and avoiding public places when possible. And be attentive to any possible symptoms – fever, increased cough, or shortness of breath from your baseline – and be more communicative with your caregivers.”
In patients with severe symptoms, COVID-19 almost always develops into pneumonia. From that point, it may develop into ARDS, which is often fatal. This occurs when the virus reaches the respiratory tree. Think of your air passages like an upside-down tree, with your throat and windpipe as the trunk. The branches are in your lungs, with the tiny air sacs called alveoli as the leaves and twigs.
As the virus moves through the lung tissues, the body reacts by causing inflammation in an attempt to slow its spread. This, in turn, causes breathing problems that may range from a dry cough for healthy individuals to breathing difficulty and shortness of breath for others. If the infection progresses to the air sacs at the end of the air passages, the situation becomes even more dangerous.
The body’s response is to pour inflammatory material into the air sacs, which then become inflamed and filled with fluid and infection debris. This compounds the breathing difficulties the patient is experiencing because the body is unable to get enough oxygen or to eliminate carbon dioxide.
If left untreated, this situation becomes severe pneumonia or ARDS, and the patient often dies. There are no medications to prevent the development of pneumonia, either. The only solution available to patients at risk is oxygen therapy, combined with medications to slow the infection and try to combat the inflammation.
Stem Cells and Inflammation
The underlying issue here is damage to the lung tissues. When damaged, the body immediately begins inflaming tissues. You can see the same thing in something as simple as a mosquito bite. It is not the histamine in the bite that makes it red and swollen – that’s the immune system attempting to isolate the histamine and prevent it from spreading.
Stem cell therapy may be able to provide not only relief for patients struggling with COVID-19-related pneumonia, but also increase their chances of survival by repairing the damaged lung tissue and reducing inflammation.
In a study published in Critical Care Perspective, titled Fifty Years of Research in ARDS, Cell-based Therapy for Acute Respiratory Distress Syndrome Biology and Potential Therapeutic Value, the authors noted,
“Of all the various cell-based therapy options, mesenchymal stem/stromal cells (MSCs) from bone marrow, adipose tissue, and umbilical cord have the most experimental data to support their potential efficacy for lung injury from both infectious and noninfectious causes.
Mechanistically, MSCs exert their beneficial effects by release of paracrine factors, microvesicles, and transfer of mitochondria, all of which have anti-inflammatory and pro-resolving effects on injured lung endothelium and alveolar epithelium, including enhancing the resolution of pulmonary edema by up-regulating sodium-dependent alveolar fluid clearance.”
Another study, this one published in Stem Cells International in 2019, notes that,
“Mesenchymal stem cells (MSCs) are able to modulate proliferation, activation, and effector function of all immune cells that play an important role in the pathogenesis of acute and chronic inflammatory lung diseases. In addition to the suppression of lung-infiltrated immune cells, MSCs have the potential to differentiate into alveolar epithelial cells in vitro and, accordingly, represent new players in cell-based therapy of inflammatory lung disorders.”
The Difference in Stem Cells
While there is evidence that supports the ability of stem cells to repair damaged lung tissue and reduce inflammation within the lungs, it is important for patients to understand the different types of stem cells used in today’s experimental therapies.
Autologous stem cells are used frequently. These are sourced from the patient’s own body and then re-infused. However, because they are the same age as the patient’s body, these stem cells are low-energy and have limited healing/regenerative capabilities. In addition, because these cells are old, they have significant mutations and damage that may trigger a negative immune system response.
Allogeneic stem cells are sourced from umbilical cord blood and tissue. They are brand-new cells and are highly energetic, capable of a lifetime of divisions and regeneration, making them better suited for this application, particularly given the fact that lung tissue is slow to heal or regenerate. Allogeneic stem cells also carry no mutations or damage, which makes them immune-naïve, meaning they are unlikely to cause any adverse immune system response.
COVID-19 related lung damage can lead to severe pneumonia and ARDS, both of which can be fatal. Stem cell therapy may be able to repair lung tissue and reduce inflammation. However, patients should remember that all stem cell treatments are experimental. The FDA has not yet approved any such therapy. Additionally, patients should ensure the physician they choose is experienced with infusion allogeneic stem cells.