TABLE 7.

Summary of therapeutic approaches using MSCs in COVID-19 patients.

Sources	COVID-19 associated diseases	Key findings	Key molecules	Study group	Year	References
Mesenchymal stem cell-derived exosomes (MSC-exosomes)	SARS-CoV-2 Pneumonia	Exosomes derived from mesenchymal stem cells (MSC-Exo) have anti-inflammatory and immune modulatory properties, as well as the ability to promote tissue regeneration, suggesting that they are a potential treatment option for SARS-CoV-2 pneumonia. When treating severe pneumonia caused by SARS-CoV-2, it is crucial to suppress the proinflammatory immune response, thereby reducing damage to both alveolar epithelial cells and capillary endothelial cells. MSC-Exo may be able to restore lung cell functionality and restore lung tissue	Keratinocyte growth factor (KGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) help in regenerating damaged tissues	N/A	2020	Akbari and Rezaie, (2020)
Bone marrow-derived mesenchymal stem cells (BM-MSCs)	COVID-19 pneumonia	MSC transplantation led to significant improvements in lung function and symptoms in 2 days. The accumulation of MSCs in the lungs may improve the lung microenvironment, protect alveolar epithelial cells, prevent pulmonary fibrosis, and improve lung function. MSCs were injected intravenously into severe patients with COVID-19 and significantly improved the inflammation situation	Increased levels of IL-10 and VEGF help repair lung damage	COVID-19 patients	2020	Leng et al. (2020)
			The C-reactive protein acts as a biomarker that measures inflammation and host response to cytokine production
Human umbilical cord mesenchymal stem cell (UC-MSC)	COVID-19 with ARDS	Improved critically ill patients. UC-MSCs were safe and did not cause serious adverse events in patients with moderate and severe COVID-19	Tocilizumab was used to block the IL-6 receptor that helps to improve clinical outcomes in patients with severe COVID-19 patients	COVID-19 patients	2020	Meng et al. (2020)
Exosomes derived from human umbilical cord mesenchymal stem cell-derived exosomes (UC-MSC-Ex)	Inflammation-induced lung damage	There are no side effects for the patients. hUC-MSCs migrate to the damaged area and replace cells. Pulmonary imaging shows an improvement in treated patients. Using MSCs at the early stage of the inflammatory factor storm, the prognosis for COVID-19 may be enhanced	Increase in anti-inflammatory factors such as IL-10	COVID-19 patients	2021	Wei et al. (2021)