RESUMO
BACKGROUND@#Retinal degenerative disease (RDD), one of the most common causes of blindness, is predominantly caused by the gradual death of retinal pigment epithelial cells (RPEs) and photoreceptors due to various causes. Cell-based therapies, such as stem cell implantation, have been developed for the treatment of RDD, but potential risks, including teratogenicity and immune reactions, have hampered their clinical application. Stem cell-derived extracellular vesicles (EVs) have recently emerged as a cell-free alternative therapeutic strategy; however, additional invasiveness and low yield of the stem cell extraction process is problematic. @*METHODS@#To overcome these limitations, we developed therapeutic EVs for the treatment of RDD which were extracted from tonsil-derived mesenchymal stem cells obtained from human tonsil tissue discarded as medical waste following tonsillectomy (T-MSC EVs). To verify the biocompatibility and cytoprotective effect of T-MSC EVs, we measured cell viability by co-culture with human RPE without or with toxic all-trans-retinal. To elucidate the cytoprotective mechanism of T-MSC EVs, we performed transcriptome sequencing using RNA extracted from RPEs. The in vivo protective effect of T-MSC EVs was evaluated using Pde6b gene knockout rats as an animal model of retinitis pigmentosa. @*RESULTS@#T-MSC EVs showed high biocompatibility and the human pigment epithelial cells were significantly protected in the presence of T-MSC EVs from the toxic effect of all-trans-retinal. In addition, T-MSC EVs showed a dosedependent cell death-delaying effect in real-time quantification of cell death. Transcriptome sequencing analysis revealed that the efficient ability of T-MSC EVs to regulate intracellular oxidative stress may be one of the reasons explaining their excellent cytoprotective effect. Additionally, intravitreally injected T-MSC EVs had an inhibitory effect on the destruction of the outer nuclear layer in the Pde6b gene knockout rat. @*CONCLUSIONS@#Together, the results of this study indicate the preventive and therapeutic effects of T-MSC EVs during the initiation and development of retinal degeneration, which may be a beneficial alternative for the treatment of RDD.
RESUMO
We estimated the effect of various immunosuppressants (ISs) and metformin (M) to provide theoretical background of optimal therapeutic strategy for de novo colon cancer after liver transplantation (LT). Three colon cancer cell lines (HT29, SW620, and HCT116) were used in in vitro studies. HT29 was also used in BALB/c-nude mice animal models. Following groups were used in both in vitro and in vivo studies: sirolimus (S), tacrolimus (T), cyclosporin A (CsA), M, metformin/sirolimus (Met/S), metformin/tacrolimus (Met/T), and metformin/cyclosporin A (Met/CsA). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed and western blot analyses were performed for mTOR pathway proteins, apoptosis proteins, and epithelial-mesenchymal-transition (EMT) proteins. Tumor volume was measured for 4 weeks after inoculation. MTT-assay revealed significant cell viability inhibition in all 3 colon cancer cell lines in groups of S, M, and Met/S. Of note, group Met/S showed synergistic effect compare to M or S group. Western blot analysis showed significant low levels of all investigated proteins in groups of S and Met/S in both in vitro and in vivo experiment. Tumor growth was significantly inhibited only in the Met/S group. Combination of Met and S showed the most potent inhibition in all colon cancer cell lines. This finding might have application for de novo colon cancer.