Mesenchymal stem cells (MSCs) are multipotent cells which can proliferate and replace dead cells in the body. MSCs also secrete immunomodulatory molecules, creating a regenerative microenvironment that has an excellent potential for tissue regeneration. MSCs can be easily isolated and grown in vitro for various applications. For the past two decades, MSCs have been used in research, and many assays and tests have been developed proving that MSCs are an excellent cell source for therapy. This review focusses on quality control parameters required for applications of MSCs including colony formation, surface markers, differentiation potentials, and telomere length. Further, the specific mechanisms of action of MSCs under various conditions such as trans-differentiation, cell fusion, mitochondrial transfer, and secretion of extracellular vesicles are discussed. This review aims to underline the applications and benefits of MSCs in regenerative medicine and tissue engineering.

Acute lung injury (ALI) during sepsis is characterized by bilateral alveolar infiltrates, lung edema, and respiratory failure. Here, we examined the efficacy of DNA methyl transferase (DNMT) inhibitor Aza (5-Aza 2-deoxycytidine), histone deacetylase (HDAC) inhibitor TSA (Trichostatin A), and combination therapy (Aza+TSA) in protection of ALI. In LPS-induced mouse ALI, post-treatment with a single dose of Aza+TSA showed a substantial attenuation of adverse lung histopathological changes, and inflammations. Importantly, these protective effects were due to significant macrophage phenotypic changes observed in LPS-stimulated macrophages treated with Aza+TSA as compared with untreated LPS-induced macrophages or LPS-stimulated macrophages treated with either drug alone. Further, we observed significantly lower levels of pro-inflammatory molecules and higher levels of anti-inflammatory molecules in LPS-induced macrophages treated with Aza+TSA than in LPS-induced macrophages treated with either drug alone. The protection was ascribed to dual effects by an inhibition of MAPK-HuR-TNF and activation of STAT3-Bcl2 pathways. Combinatorial treatment with Aza+TSA reduces inflammation and promotes an anti-inflammatory M2 macrophage phenotype in ALI. This finding gives further evidence that the epigenetic treatment has a therapeutic potential for patients with sepsis.