TGF-β1 overexpressing human MSCs generated using gene editing show robust therapeutic potential for treating collagen-induced arthritis.

Transforming growth factor β (TGF-β) plays a pivotal role in cartilage differentiation and other functions of mesenchymal stem cells (MSCs). In this study, we investigated the therapeutic potential of TGF-β1 overexpressing amniotic MSCs (AMMs) generated using gene editing in a mouse model of damaged cartilage. The TGF-β1 gene was inserted into a safe harbor genomic locus in AMMs using transcription activator-like effector nucleases. The chondrogenic properties of TGF-β1-overexpressing AMMs (AMM/T) were characterized using reverse transcription polymerase chain reaction (RT-PCR), quantitative RT-PCR, and histological analysis, and their therapeutic effects were evaluated in mouse model of collagen-induced arthritis (CIA). AMM/T expressed cartilage-specific genes and showed intense Safranin O and Alcian blue staining. Furthermore, injecting AMM/T attenuated CIA progression compared with AMM injection, and increased the regulatory T (Treg) cell population, while suppressing T helper (Th)17 cell activation in CIA mice. Proinflammatory factors, such as interleukin-1β (IL-1β), IL-6, monocyte chemoattractant protein-1, and tumor necrosis factor-α were significantly decreased in AMM/T injected CIA mice compared with their AMM injected counterparts. In conclusion, genome-edited AMMs overexpressing TGF-β1 may be a novel and alternative therapeutic option for protecting cartilage and treating inflammatory joint arthritis.