Differences between the pre-menopausal and post-menopausal uterine fibroid vasculature

OBJECTIVES

To quantitatively examine differences in microvascular density between fibroid and myometrial tissue from fibroid uteri removed at hysterectomy, both before and after the menopause, and with hormone replacement therapy.

METHODS

Factor VIII immunostaining of formalin fixed tissues was used to identify blood vessels, and the vessels counted by an investigator blinded to tissue type or menopausal status.

RESULTS

The mean myometrial: fibroid MVD ratio was 2.38 higher in the post-menopausal group (95% CI: 0.12, 4.65, p=0.0474) than in the pre-menopausal group, with the hormone therapy (HT)-using post-menopausal group lying in between. An increase in microvascular density in the myometrium after the menopause was responsible for most of the change in ratios seen between the pre and post-menopausal pairs. There was a trend to increasing myometrial MVD with increasing number of years post-menopause.

CONCLUSIONS

Myometrial microvascular density increases markedly after the menopause, while fibroid microvascular density does not alter. Thus, the difference between myometrial and fibroid vasculature becomes greater after the menopause. The implications of this for the treatment of fibroids in post-menopausal women is discussed.

266.Human endometrial cycle stages can be determined by global gene expression profiling

Endometrium is a dynamic tissue which undergoes cyclic changes each month, under the overall control of oestrogen and progesterone. The aims of this study were to investigate the changing global gene expression profile of human endometrium during the menstrual cycle using microarray technology and to determine the correlation between histopathological evaluation and molecular profile of the samples. Curettings of endometrium were collected from 43 cycling women and immediately snap frozen. The menstrual cycle was divided into seven stages by histological evaluation. Standard two-color cDNA microarrays were performed on the 43 samples against a common reference, using a 10.5 K cDNA glass slide microarray. Expressed genes were identified using a Scanarray 5000 UV laser scanner. Quantarray software was used to quantify the relative gene expression values. Normalisation and visualisation of the gene expression changes were performed using the GeneSpring software package. Hierarchical clustering of all 43 samples was performed, based on the expression profile of 571 genes, which were identified as differentially expressed by parametric ANOVA with Benjamini-Hochberg correction. The 43 samples were sorted into nine groups which all agreed with histopathology by either being in the same group or an adjacent group apart from four samples. For further analysis, the four outliers were removed, one group was excluded due to lack of replicates and two groups were merged to get the final molecular classification of the cycle. The statistical analysis was repeated and 1452 genes were identified as differentially expressed at P d 0.05. The data were also independently analysed by a CSIRO algorithm called GeneRave and the results from both methods were comparable. mRNA expression profiles of the genes TGF a (Hs.170009), NCR3 (Hs.509513) and FUT4 (Hs.390420) were verified using real-time PCR. We have shown for the first time that endometrial cycle stage prediction is possible based on global gene expression profile.

Myometrial microvascular endothelial cells express oxytocin receptor

OBJECTIVE

1. To establish whether microvascular endothelial cells from the human myometrium (MMECs) express oxytocin receptor, and to compare its expression levels relative to HUVECs. 2. To verify an up-regulation of oxytocin receptor expression in MMECs as a result of vascular endothelial growth factor (VEGF), which had been found in a previous study.

DESIGN

Laboratory scientific study.

SETTING

University department.

POPULATION OR SAMPLE

Myometrial biopsies from 12 hysterectomy specimens.

METHODS

MMECs and HUVECs were established in vitro. Immunohistochemistry of in vitro cultures was performed to investigate protein expression of the oxytocin receptor. Semi-quantitative RT-PCR and Northern blots were performed to examine the presence and relative abundance of oxytocin receptor mRNA in MMECs and HUVECs, and in both cell types with and without VEGF. Total RNA from oxytocin acetate (100 nmol/L) and vehicle stimulated endothelial cell cultures was used to examine gene expression differences on a 10.5K cDNA microarray.

MAIN OUTCOME MEASURES

Oxytocin receptor mRNA and protein; gene expression anlysis.

RESULTS

Oxytocin receptor mRNA and protein was present in MMECs. The level of expression was the same as for the HUVECs, but much less than the pregnant myometrium. No effect on gene expression could be demonstrated by gene expression microarray following 10 hours of oxytocin stimulation. Twenty-four hours of VEGF stimulation did not significantly alter oxytocin receptor mRNA expression in MMECs or HUVECs.

CONCLUSION

The myometrial microvasculature expresses oxytocin receptor. This finding means that oxytocin may exert some of its effects on the myometrial microvasculature. No evidence could be found for a transcriptional effect of oxytocin stimulation in this study, but further work on the role of the myometrial vessel oxytocin receptor is needed.

Microarray analysis of VEGF-responsive genes in myometrial endothelial cells

There is evidence that the vasculature of different organs display different functional characteristics in response to cytokines and growth factors. The aim of this study was to use cDNA gene expression microarray to analyse changes in gene expression following stimulation of myometrial microvascular endothelial cells (MMECs) with vascular endothelial growth factor (VEGF). Primary isolates of MMECs were obtained from fresh hysterectomy specimens and purified with magnetic beads. Cells were stimulated with 15 ng/ml VEGF for 3, 6 and 12 h, and two unstimulated experiments served as controls. A total of six arrays was performed over these time-points. A total of 110 genes were identified as up-regulated by VEGF, 19% of which (21 genes) have previously been reported as up-regulated by VEGF or by angiogenesis. Among the novel genes to be up-regulated by VEGF were brain-derived growth factor, oxytocin receptor and estrogen sulphotransferase. The significance of the genes identified in the physiological and pathological functioning of the myometrial vasculature is discussed.