Gene expression in human ovarian tissue after xenografting.

Cryobanking and transplantation of ovarian tissue is a promising approach to restore fertility in cancer patients. However, ischemic stress following avascular ovarian cortex grafting is known to induce stromal tissue fibrosis and alterations in follicular development. The aim of the study was to analyze the impact of freeze-thawing and grafting procedures on gene expression in human ovarian tissue. Frozen-thawed ovarian tissue from 14 patients was xenografted for 7 days to nude mice and one ungrafted fragment was used as a control. Immediately after recovery, grafts were processed for RNA extraction and histological analysis. Their expression profile was screened by whole-genome oligonucleotide array (n = 4) and validated by reverse-transcriptase polymerase chain analysis (n = 10). After data filtering, the Limma package was used to build a linear regression model for each gene and to compute its fold change between tissues on Days 0 and 7. After adjusting the P-value by the Sidak method, 84 of the transcripts were significantly altered after 7 days of grafting, including matrix metalloproteinase-9 and -14 and angiogenic factors such as placental growth factor and C-X-C chemokine receptor type 4 (CXCR4). Major biological processes were related to tissue remodeling, including secretory processes, cellular adhesion and response to chemical and hormonal stimuli. Angiopoietin signaling, the interleukin-8 pathway and peroxisome proliferator-activated receptor activation were shown to be differentially regulated. On Day 7, overexpression was confirmed by PCR for interleukin-8, transforming growth factor-beta 1, matrix metalloproteinase-14 and CXCR4, compared with ungrafted controls. In conclusion, new as well as known genes involved in tissue restructuring and angiogenesis were identified and found to play a key role during the first days after human ovarian tissue transplantation. This will facilitate the development of strategies to optimize grafting techniques.

Interpretation of the nano-electron-diffraction patterns along the five-fold axis of decahedral gold nanoparticles.

The transition from 10-fold to 5-fold symmetry was observed during the analysis of nanodiffraction patterns of a gold decahedral multiple twinned nanoparticle of 15 nm in diameter. The analysis shows that as the convergence of the beam is increased, the rotational symmetry of the diffraction pattern shifts from 10- to 5-fold. The 10-fold symmetry predicted by Friedel's law is lost by the asymmetric shift of the diffraction spots, an effect that becomes more noticeable as the electron beam convergence increases. Dynamical and kinematical diffraction calculations indicate this decrease in symmetry is the result of a double refraction effect coupled with the variation of the dynamical diffraction conditions arising from a varying electron beam convergence.

Xenotransplantation of human ovarian tissue to nude mice: comparison between four grafting sites.

BACKGROUND: This study was designed to assess the impact of different ovarian tissue transplantation sites on the follicular pool and ovarian tissue integrity after short-term grafting, since there is no consensus in the literature as to the optimal grafting site in experimental models. METHODS: Frozen-thawed ovarian tissue from eight patients was grafted for 1 or 3 weeks to the peritoneum, inside the ovarian bursa, under the skin and into the muscle of 16 nude mice. Assessment of follicular density and follicle classification was carried out by histological analysis. Proliferative activity was evidenced by immunostaining with anti-Ki-67 antibodies, and fibrotic areas were analyzed by morphometry on histological slides. RESULTS: One week post-transplantation, the proportion of Ki-67-positive primordial follicles was higher (20-42%) than in controls (1.7%), demonstrating follicular activation in all four sites. Despite this activation, primordial follicles were still found 3 weeks post-grafting, (34.1-66.9% of the follicle population), most of them quiescent, as indicated by the absence of Ki-67 immunostaining. Cryopreservation and grafting resulted in extensive fibrosis in the stroma. This fibrosis was significantly less pronounced in intramuscular (IM) grafts, representing 18.8% of the surface versus 44.7-60.5% for other sites, after 3 weeks of grafting. CONCLUSIONS: All four grafting sites equally supported early follicular growth and preserved some quiescent follicles after short-term frozen-thawed human ovarian tissue transplantation. The extensive fibrosis observed does not appear to have a major impact on early follicle development, but its long-term effects must be investigated. The graft environment may be implicated in the preservation of the stroma, as suggested by a lower degree of fibrosis in the IM site.