The effects of crocetin on oxidative stress induced ARPE-19 cells by H2O2.

The anti-apoptotic and antioxidant effects of crocetin was aimed to investigate on the oxidative damage model of ARPE-19 cells. The oxidative damage in ARPE cells was developed by H2O2 treatment at 800 µM. Different doses of crocetin (1-80 µM) were applied for 24 h, and the effects on viability were evaluated to find out the optimum drug dose. At first, three effective doses of crocetin (10, 20, 40 µM) on cell viability were selected for further analyses. The levels of superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH) were determined, and the expression of pro-apoptotic Bax gene and anti-apoptotic Bcl-2 gene were evaluated. The most effective crocetin dose on cell viability was found to be 10 µM. After the H2O2 treatment, SOD and GSH were decreased and MDA were increased significantly (p = 0.011, 0.037, 0.018, respectively). Following the crocetin treatment at 10 µM, SOD and GSH activities were improved compared to the no drug group; and MDA level was declined remarkably (p = 0.022, 0.019, 0.029, respectively). The Bcl-2 level was significantly decreased (p < 0.01), while the Bax1 and Nrf2 expression and ROS level was increased significantly in the damage model group (p < 0.01). After the drug treatment, the Bax1 and Nrf2 expression level were decreased in all groups (p < 0.01). The increase in Bcl-2 expression was significant in crocetin 40 µM (p < 0.05) and the decrease in ROS level were significant in 20 µM and 40 µM doses of crocetin (p < 0.05). It has been shown that crocetin might be used as an antioxidant and anti-apoptotic agent on the hindering the effect of the oxidative damage. Following the development of the oxidative stress in the cells, crocetin reversed the damage signals. By the in vitro tests, it was shown that crocetin might be considered as an effective molecule to be used in the AMD treatment.

The therapeutical effects of damage-specific stress induced exosomes on the cisplatin nephrotoxicity IN VIVO.

Cisplatin is one of the metal containing drugs for the solid cancer treatments. However, its side-effects limit its application in the cancer treatment. Stem cell therapy is a promising treatment for the tissue damage caused by the chemotherapeutic agents, like cisplatin. Exosomes secreted by mesenchymal stem cells (MSCs) could be used for cell-free regenerative treatment, but their potency and reproducibility are questionable. In this study, the microenvironment of the renal tubular epithelial cells was mimicked by coculture of endothelial-, renal proximal tubule epithelial- and fibroblast cells. Cisplatin was applied to this tricell culture model, and the secreted rescue signals were collected and used to induce MSCs. From these stress-induced MSCs, the (stress-induced) exosomes were collected and used for the cell-free therapeutic treatment of cisplatin-treated rats with acute kidney injury. The composition of the stress-induces exosomes was compared with the non-induced exosomes and found that the expression of some critical factors for cell proliferation, repair mechanism and oxidative stress was improved. The cisplatin-damaged renal tissue showed substantial recovery after the treatment with stress-induced exosomes compared to the treatment with non-induced exosomes. Although, the non-induced exosomes showed their activity mostly as cytoprotective, the induced exosomes further involved actively in the tissue regeneration, like MSCs. It was shown that the exosomes could be reprogrammed to improve their therapeutic effect to be used in cell-free regenerative medicine. Further, cisplatin-induced tissue damage in the kidney might be effectively prevented and used for tissue regeneration by use of induced exosomes generated for a particular damage.

Guiding the Differentiation Direction of Pancreatic Islet-Derived Stem Cells by Glycated Collagen.

The microenvironment is an important factor of stem cells regulating their maintenance, survival, and differentiation. The glycation of proteins with reducing sugars through nonenzymatic reactions induces the collagen cross-linking, which causes tissue stiffening, which is enhanced during aging and diabetes. In this study, we aimed to analyze the effect of glycated collagen on the stem cell culture and differentiation. The collagen type 1 was modified by glycation with mannose, rhamnose, arabinose, and glucose. After the culture of mesenchymal stem cells on the coated surfaces with glycated collagen, the differences in cell adhesion, proliferation, and differentiation were compared. The results showed that the modifications did not induce apoptosis or cause cell death. However, the culture of cells on modified collagens improved the proliferation. It was found that the mannose-modified collagen stimulated the adipogenic differentiation of stem cells, and rhamnose-modified collagen supports the differentiation into both osteogenic and insulin-producing cells. The low concentration of monosaccharides during glycation process improved the characteristics of the matrix protein in favor of stem cell differentiation. Modification of the collagen by glycation might be used as a tool to improve natural polymers for material-induced stem cell differentiation in the future.

Improved insulin-secreting properties of pancreatic islet mesenchymal stem cells by constitutive expression of Pax4 and MafA.

For long-term treatment of diabetes type 1, transplantation of insulin-producing beta cells may be a promising method, but the limited number of islets for transplantation requires the development of different approaches. In this study, we aimed to generate betalike insulin-producing cells. For this purpose, MafA, Pax4, and Ngn3 genes were transferred into pancreatic islet-derived mesenchymal stem cells, and the effect of their ectopic expressions on differentiation efficiency was examined. Stemness properties of pancreatic islet stem cells were characterized. The 3 genes were transfected by electroporation and expressed constitutively. The transfected cells were further stimulated to differentiate by using chemical induction. Pax4 expression had significant effects on differentiation into insulin-producing cells. Although it caused morphological alterations in cells, similar to epithelial cells, the insulin secretion levels remained lower than those of the cell line cotransfected with MafA and Pax4. Cotransfection of the 3 transcription factors did not further improve the beta-like cell generation. MafA and Pax4 ectopic expression resulted in improved differentiation efficiency into insulin-secreting cells. However, support of this differentiation process using additional chemical induction may sufice to overcome control by endogenous regulatory pathways.