Exosomes derived from mesenchymal stem cells inhibit mitochondrial dysfunction-induced apoptosis of chondrocytes via p38, ERK, and Akt pathways.

Osteoarthritis (OA) is the most common chronic joint disease worldwide. Chondrocyte, as the only resident cell type in cartilage, its apoptosis is of pathogenetic significance in OA. Mesenchymal stem cell (MSC)-based-therapy has been proved effective in OA in animals and clinical studies. Nowadays, the regenerative potential of MSC-based therapy is mostly attributed to its paracrine secretion, in which exosomes may play an important role. In the present study, we aimed to find out the significance of MSC-derived exosomes (MSC-Exos) on the viability of chondrocytes under normal and inflammatory conditions. Bone marrow MSCs (BMSCs) and chondrocytes from rabbits were cultured in vitro. BMSC-Exos were isolated by an ultracentrifugation method. Transmission electron microscopy and Western blot were used to identify exosomes. The internalization of BMSC-Exos into chondrocytes was observed by fluorescent microscope. The viability and apoptosis of chondrocytes induced by IL-1ß were tested through MTT method, Hoechst33324 dying, and mitochondrial damage measurement. Phosphorylation of p38, ERK, and Akt were evaluated by Western blot. The results showed that BMSC-Exos were round-shaped. Co-culturing BMSC-Exos with chondrocytes could observe the uptake of BMSC-Exos by chondrocytes. The viability decreased, apoptosis occurred, and the mitochondrial membrane potential of chondrocytes changed a lot when IL-1ß were given, but all the changes were almost abolished when BMSC-Exos was added. Furthermore, the phosphorylation of p38 and ERK were inhibited, and phosphorylation of Akt was promoted by BMSC-Exos compared with IL-1ß group. The present study demonstrated that BMSC-Exos inhibited mitochondrial-induced apoptosis in response to IL-1ß, and p38, ERK, and Akt pathways were involved. BMSC-Exo might represent a novel cell-free therapeutic approach for the treatment of OA.

Evaluation of alternative rice planthopper control by the combined action of oil-formulated Metarhizium anisopliae and low-rate buprofezin.

BACKGROUND: High resistance of brown planthopper (BPH) Nilaparvata lugens Stål to common insecticides is a challenge for control of the pest. An alternative control strategy based on the combined application of fungal and chemical agents has been evaluated. RESULTS: Three gradient spore concentrations of oil-formulated Metarhizium anisopliae (Metschnikoff) Sorokin (Ma456) were sprayed onto third-instar nymphs in five bioassays comprising the low buprofezin rates of 0, 10, 20, 30 and 40 µg mL(-1) respectively. Fungal LC(50) after 1 week at 25 °C and 14:10 h light:dark photoperiod decreased from 386 conidia mm(-2) in the buprofezin-free bioassay to 40 at the highest chemical rate. Buprofezin (LC(50): 1647, 486 and 233 µg mL(-1) on days 2 to 4) had no significant effect on the fungal outgrowths of mycosis-killed cadavers at the low application rates. The fungal infection was found to cause 81% reduction in reproductive potential of BPH adults. In two 40 day field trials, significant planthopper (mainly BPH) control (54-60%) was achieved by biweekly sprays of two fungal candidates (Ma456 and Ma576) at 1.5 × 10(13) conidia ha(-1) and elevated to 80-83% by incorporating 30.8 g buprofezin ha(-1) into the fungal sprays. CONCLUSION: The combined application of the fungal and chemical agents is a promising alternative strategy for BPH control.

Selection of global Metarhizium isolates for the control of the rice pest Nilaparvata lugens (Homoptera: Delphacidae).

BACKGROUND: This study was initiated to search for fungal candidates for microbial control of brown planthopper (BPH) Nilaparvata lugens Stål, to which little attention has been paid in the past two decades. RESULTS: Thirty-five isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and M. flavoviride Gams & Rozsypal from different host insects worldwide were bioassayed for their lethal effects against third-instar BPH nymphs at 25 degrees C and a 14:10 h light:dark photoperiod at ca 1000 conidia mm(-2). On day 9 post-treatment, mortality attributable to mycosis ranged from 6.5 to 64.2% and differed significantly among the tested isolates with no apparent relationship to their host origin. Only two BPH-derived M. anisopliae isolates from the Philippines (ARSEF456) and Indonesia (ARSEF576) killed >50% of the nymphs. Both isolates were further bioassayed for time-concentration-mortality responses of the nymphs to the sprays of 19-29, 118-164 and 978-1088 conidia mm(-2) in repeated bioassays. The resultant data fitted a time-concentration-mortality model very well. Their LC(50) values were estimated as 731 and 1124 conidia mm(-2) on day 7 and fell to 284 and 306 conidia mm(-2), respectively, on day 10. CONCLUSION: The two M. anisopliae isolates are potential biocontrol agents of BPH for further research. This is the first report of the lethal effects of global Metarhizium isolates on the rice pest.

Formation of microchimerism in rat small bowel transplantation by splenocyte infusion.

AIM: To investigate the effect of donor splenocyte infusion combined with cyclosporine A (CsA) on rejection of rat small bowel transplantation (SBT). METHODS: Male Sprague-Dawley (SD) rats and female Wistar rats weighing 230-270 g were used as donors and recipients respectively in the study. Heterotopic small bowel transplantation was performed. The rats were divided into three groups: group one receiving allotransplantation (SD rarr Wistar), group two receiving allotransplantation (SD rarr Wistar) + donor splenocyte infusion, group three receiving allotransplantation (SD rarr Wistar) + donor splenocyte infusion + CsA followed by CsA 10 mg/kg per day after transplantation, in which recipient Wistar rats were injected with 2 x 10(8) SD splenocytes 28 d before transplantation, and treated with CsA after transplantation. Finally, the specific DNA fragment of donor Y chromosome was detected in recipient peripheral blood and skin by PCR. The survival time after small bowel transplantation was observed. Gross and histopathological examinations were performed. RESULTS: The survival time after small bowel trans-plantation was 7.1 +/- 1.2 d in group 1, 18.4 +/- 3.6 d in group 2 and 31.5 +/- 3.1 d in group 3. The survival time was significant longer (P < 0.01) in group 3 than in groups 1 and 2. The gross and histopathological examination showed that the rejection degree in group 3 was lower than that in groups 1 and 2. CONCLUSION: Donor splenocyte infusion combined with CsA decreases remarkably the rejection and prolongs the survival time after rat small bowel transplantation.