Immortalized Human Adipose Tissue-Derived Mesenchymal Stem Cells-SV40 (Tet-on)

Exosomes Derived from Mesenchymal Stem Cells Primed With Disease-Condition-Serum Enhanced TGF-Β1 Production

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease characterized by synovial inflammation-mediated progressive destruction of the cartilage and bone, resulting in reduced quality of life. Choi et al. primed human telomerase reverse transcriptase-overexpressing immortalized human adipose tissue-derived mesenchymal stem cells (iMSCs) with serum derived from a non-human primate RA model and studied the immunomodulatory ability of exosomes obtained from primed iMSCs.

Exosomes from iMSCs (Exo-FBS), iMSCs with RA serum (Exo-RA), or non-RA serum (Exo-non-RA) were isolated. TEM was used to confirm shape and size (Fig. 1A, B). NTA was used to verify size distribution. CD81 production was the highest in Exo-RA (Fig. 1C). The exosome number and size were the highest and smallest in Exo-RA (Fig. 1D, E). The analysis of exosomes produced from 107 iMSCs showed that the amount of TGF-β1 was 15,376.4 ± 1693.2 pg in Exo-FBS and 27,242.4 ± 1564.8 pg in Exo-RA; the amount of TGF-β1 was significantly higher in Exo-RA than in Exo-FBS (Fig. 1F). The analysis of exosomes produced from 107 iMSCs showed that the amount of IL-1Ra was 24.9 ± 3.9 pg in Exo-FBS and 27.0 ± 2.5 pg in Exo-RA (Fig. 1G). The amount of prostaglandin E2 (PGE2) levels was 152.3 ± 3.9 pg in Exo-FBS and 162.8 ± 8.3 pg in Exo-RA (Fig. 1H).

Effect of Quercetin in the Presence of Cocl2 as an Inducing Hypoxia Agent on hTERT-MSC Viability

Studying how small molecules affect stem cell characteristics under normal and low-oxygen conditions is key to optimizing biomedical applications. Aref et al. examined the effects of Quercetin (QC), in combination with hypoxia mimetic CoCl2, on the biological properties of hTERT-MSCs.

MTT assay revealed that 24-h exposure to CoCl2 at ≤ 100 µM increased hTERT-MSC viability, which was significant at 50 µM (Fig. 2A). In contrast, 200–800 µM CoCl2 significantly decreased cell viability at ≥ 400 µM. All concentrations of CoCl2 led to reduced viability of hTERT-MSCs at 48 and 72 h with the greatest decline observed at 72 h. A subsequent MTT assay assessed QC's impact on hTERT-MSC viability. The results showed that QC at 2.5–200 µM did not significantly change cell viability, while 320 µM QC only slightly increased viability at 24 h. However, 640 µM QC significantly increased hTERT-MSC viability at 24 and 48 h (Fig. 2B), while 1280 µM QC increased cell viability at all time points. Notably, the higher the QC concentration, the shorter the treatment time required to increase viability. We also performed MTT assay to determine the combined effects of QC at 2.5–1280 µM and 200 µM CoCl2 on hTERT-MSC viability. QC at ≤ 40 µM significantly decreased viability in a time-dependent manner (Fig. 2C). Cell viability was significantly increased by both 640 and 1280 µM QC with the effects of 1280 µM QC being more pronounced throughout all time points.