Mesenchymal stem cells-bridge catalyst between innate and adaptive immunity in COVID 19.

Majority of patients infected with the COVID 19 virus display a mild to moderate course of disease and spontaneously recover at 14-20 days. However, about 15% of patients progress to severe stages and 2.5% of these patients succumb to this illness. Most patients with severe disease belong to the elderly age group (<65 years of age) and have multiple associated co-morbidities. The immune responses induced by the COVID 19 virus, during the incubation and non-severe stages, requires the early initiation of a specific adaptive immune response to eliminate the virus and prevent the progress to severe stages. In patients with a dysfunctional bridge adaptive immunity, the innate immune response becomes exaggerated due to the lack of feedback from the adaptive immune cells. The resultant cytokine storm is responsible for the severe lung injury leading to acute respiratory distress syndrome seen in COVID 19 patients. Mesenchymal stem cells are known to suppress overactive immune responses as well as bring about tissue regeneration and repair. This immuno-modulatory effect of MSCs could hold potential to manage a patient with severe symptoms of COVID 19 infection due to a dysfunctional adaptive immune system.