Mesenchymal stem cell therapy for COVID-19.

The coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) started in December 2019 and affected the whole world in a short time. The course of the disease depends on the person's immune system, physical properties, health status, etc. as it varies according to its characteristics while it is asymptomatic in some people, it causes fatal processes that start with flu-like symptoms such as cough, fever, respiratory distress in some people and progress to acute respiratory distress syndrome (ARDS), severe pneumonia and multi-organ dysfunction, and the basic mechanism underlying these effects known as a cytokine storm. There is no specific effective antiviral drug or vaccine in treatment yet. Supportive/alternative treatment methods are needed as both the desired effect cannot be achieved and undesirable side effects are seen with the current treatments used in the clinic. Mesenchymal stem cells (MSCs) are frequently preferred recently from basic studies to clinical studies and are effective and safe in immune-mediated inflammatory diseases such as Systemic Lupus Erythematosus, Graft-versus-Host disease. MSCs can secrete many types of cytokines through paracrine secretion or directly interact with immune cells leading to immunomodulation. According to the results of the completed studies; it has been stated that the cytokine storm caused by the overstimulation of the immune system decreases and even damage of the cytokine storm on organs decreases, respiratory distress is relieved and contributes to the healing process by repairing damaged tissues. In this review, clinical trials completed/ongoing on MSCs recommended for treating COVID-19, a global problem, are reviewed and the review is prepared to specify the existence of such a route to clinicians.