[Protective effect of lycopene on human spermatozoa during cryopreservation and its mechanism].

OBJECTIVE: To investigate the protective effect of lycopene against cryopreservation injury of post-thawing human sperm and its mechanism. METHODS: Semen samples were collected from 25 volunteers, each sample equally divided into four parts to be cryopreserved with cryoprotectant only (Ly0 control) or cryoprotectant + lycopene at the concentrations of 2 (Ly2), 5 (Ly5), and 10 µmol/L (Ly10), respectively. Before and after thawing, the semen samples were subjected to computer-assisted semen analysis ( CASA) for sperm kinematics, flow cytometry for sperm apoptosis, thiobarbituric acid assay for malondialdehyde (MDA) concentration, and JC-1 fluorescent staining for the sperm mitochondrial membrane potential (MMP). RESULTS: After cryopreservation, sperm motility was markedly decreased in all the groups (P < 0.01). The rate of sperm apoptosis was significantly lower in the Ly5 group than in the Ly0 control ([25.68 ± 4.36]% vs [33.26 ± 4.78]%, P < 0.05), while sperm MMP remarkably higher in the former than in the latter ([66.18 ± 14.23]% vs [55.24 ± 12.31]%, P < 0.05). The Ly2, Ly5 and Ly10 groups showed no statistically significance differences in the MDA level from the Ly0 control (P > 0.05). CONCLUSION: Addition of lycopene at a proper concentration to cryoprotectant may reduce oxidative damage to sperm mitochondria in the freezing-thawing process, attenuate oxidative stress injury induced by reactive oxygen species to sperm plasma membrane, and improve the anti-apoptosis ability of sperm.

Plasmid-based Stat3 siRNA delivered by hydroxyapatite nanoparticles suppresses mouse prostate tumour growth in vivo.

DNA vector-based Stat3-specific RNA interference (si-Stat3) blocks Stat3 signalling and inhibits prostate tumour growth. However, the antitumour activity depends on the efficient delivery of si-Stat3. The effects on the growth of mouse prostate cancer cells of si-Stat3 delivered by hydroxyapatite were determined in this study. RM-1 tumour blocks were transplanted into C57BL/6 mice. CaCl2-modified hydroxyapatite carrying si-Stat3 plasmids were injected into tumours, and tumour growth and histology were determined. The expression levels of Stat3, pTyr-Stat3, Bcl-2, Bax, Caspase3, VEGF and cyclin D1 were measured by western blot analysis. Amounts of apoptosis in cancer cells were analysed with immunohistochemistry and the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) assay. The results showed that hydroxyapatite-delivered si-Stat3 significantly suppressed tumour growth up to 74% (P < 0.01). Stat3 expression was dramatically downregulated in the tumours. The immunohistochemistry and TUNEL results showed that si-Stat3-induced apoptosis (up to 42%, P < 0.01). The Stat3 downstream genes Bcl-2, VEGF and cyclin D1 were also strongly downregulated in the tumour tissues that also displayed significant increases in Bax expression and Caspase3 activity. These results suggest that hydroxyapatite can be used for the in vivo delivery of plasmid-based siRNAs into tumours.