Reproductive Sciences

Regulation of ovarian follicle development depends on endocrine- and paracrine-acting hormones, the 3-dimensional architecture of the follicle, and the physical rigidity of the surrounding tissue. These 3 forces are integrated throughout the life cycle of the follicle to ensure appropriate hormone secretion, differentiation of the somatic cells, and maturation of the oocyte. The process of in-follicle maturation provides a new tool for understanding ovarian follicle development under the influence of these factors.

In vitro 3-dimensional (3D) cell cultures produce valuable models that mimic 3D tissue organization and function and enhance the understanding of cell/tissue function under normal and pathological situations. Tissue function depends on the interactions between cells and the extracellular matrix; thus, effective 3D cell cultures rely on the use of appropriate extracellular matrix cues. Noticeable progress in 3D cell culture was obtained from studies with epithelial cells from organs of the female reproductive system including the mammary glands, the uterus, and the ovaries. These models show that replicating normal tissue organization in the resting phase is a prerequisite for appropriate physiological and pathological investigations. The authors' goals are to explain the importance of mimicking detailed aspects of normal epithelial organization and function, such as basoapical polarity, in 3D cell culture and to discuss how effective 3D cell culture models can lead to meaningful applications in reproductive biology.

Progesterone plays a pivotal role in controlling uterine leiomyoma growth. The authors review studies they conducted to evaluate the comparative effects of asoprisnil on proliferation, apoptosis, and growth factor expression in cultured leiomyoma and normal myometrial cells. Treatment with asoprisnil decreased the proliferating cell nuclear antigen—positive rate and the number of viable cells and increased the terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5'-triphosphate nick end labeling— positive rate in cultured leiomyoma cells in a dose-dependent manner ( P < .05). Similarly, asoprisnil decreased Bcl-2 expression and increased cleaved caspase-3 and cleaved poly(adenosine 5′-diphosphate-ribose) polymerase in leiomyoma cells but not in normal myometrial cells. Similarly, asoprisnil decreased epidermal growth factor (EGF), insulin-like growth factor—I (IGF-I), and transforming growth factor (TGF) β mRNA and protein expression, as well as EGF receptor, IGF-IRα, and TGF RII protein expression in leiomyoma cells but not in cultured normal myometrial cells. These results suggest that asoprisnil selectively inhibits proliferation by downregulating the growth factors and their receptor expression and induces apoptosis in leiomyoma cells without affecting proliferation and apoptosis in normal myometrial cells.

During pregnancy, trophoblasts invade and transform the maternal spiral arteries that supply blood to the placenta. Recent work has revealed that this process occurs in several stages, and details of the molecular and cellular mechanisms are beginning to emerge, including changes that precede or accompany trophoblastic colonization of the vascular media. Disruption and eventual loss of smooth muscle cells and their associated extracellular matrix are central to physiological transformation. Advances in understanding will lead to the identification of the causative factors involved in failure of remodeling in pathological pregnancies and suggest novel diagnostic and therapeutic avenues.

In the third trimester of normal pregnancy, the human fetal membranes become increasingly distended and use mechanotransduction and its downstream signaling to remodel and function. Their overdistension either by multifetal pregnancy or by polyhydramnios often leads to preterm birth, but the mechanism is unclear. Stretching of the fetal membranes in vitro upregulates several cytokines and enzymes that can drive collagen degradation, leading to membrane rupture. The sensitivity of this response appears to be specific for different cell types and is likely to result from differential activation of some key transcription factors and cofactors. Few cytokines in the fetal membranes respond to stretch: the most robust of these is pre—B-cell colony-enhancing factor (PBEF). This is constitutively expressed and protects the amnion cells from apoptosis caused by chronic static distension. However, it can also be stimulated by inflammation, infection, and hypoxia and upregulates a number of proinflammatory cytokines, chemokines, and enzymes important in the initiation of parturition. Therefore, it is proposed here that PBEF functions in normal pregnancy to protect the amnion cells as they become increasingly stretched, but if stimulated, it can initiate key events leading to parturition.

The human fetal membranes are complex tissues that perform many important functions during gestation. The extracellular matrix provides their strength to withstand the forces directed from the fetus and myometrium. Relaxin is a collagenolytic hormone that causes increased production of the matrix metalloproteinases. Its expression from the decidua is increased in patients with preterm premature rupture of the membranes, and its leucine-rich G receptor 7 is upregulated at preterm. The authors previously showed that relaxin is not involved in the infection-mediated cytokine response, but in the absence of infection, it causes increased secretion of both interleukin -6 and interleukin-8 from the membranes. In this article, the authors propose that relaxin is one of a number of sterile stimuli capable of causing increased proinflammatory cytokines, similar to but less robust than the effects of infection. These probably represent distinct inflammatory pathways involving different intracellular signaling events, which can result in either preterm premature rupture of the membranes or preterm labor. The current challenge is to fully understand these pathways and to clarify their similarities and differences.

It is thought that preeclampsia results from a shallow invasion of the extravillous trophoblast into the decidua and maternal vessels, which in turn leads to hypoxia and uteroplacental insufficiency. Here, the authors focus on the expression of the proangiogenic secreted molecules CYR61 (CCN1) and NOV (CCN3) in human placentae during normal pregnancy compared with preeclamptic placentae. CYR61 and NOV are strongly expressed in endothelial cells as well as in the extravillous trophoblast, with increasing levels during placental development. Interestingly, the authors found significantly decreased levels in early preeclamptic placentae compared with matched controls. Whereas both CYR61 and NOV proteins are present at constant high levels in the sera of nonpregnant and pregnant women, in the sera of patients with early-onset preeclampsia, levels were significantly reduced. The authors suggest that the reduction of both CCN molecules in preeclampsia could be 1 reason underlying the failure of uterine vascular remodeling. Moreover, their low maternal serum levels could serve as biomarkers for early diagnosis of this disease.

A greater understanding of the processes that regulate cervical remodeling during pregnancy, parturition, and the postpartum period is required to understand causes of preterm and posterm birth in which abnormal cervical function is the primary culprit. In the current study, gene expression patterns unique to cervical ripening as compared with cervical dilation and/or postpartum repair are identified in a mouse model. Genes differentially regulated from gestation day 15 to late day 18 reveal processes important for cervical ripening. Genes differentially regulated from late day 18 to 2 hours after birth reveal processes that could be important during cervical dilation or the postpartum recovery period. Based on expression patterns, cervical ripening requires a downregulation of collagen assembly genes; increased synthesis of glycosaminoglycans that disrupt the matrix, such as hyaluronan; increased metabolism of progesterone; and changes in epithelial barrier properties. The latter phases of dilation and postpartum recovery are associated with increased assembly of mature collagen, synthesis of matrix proteins that promote a dense connective tissue, activation of inflammatory responses, prostaglandin synthesis, and further changes in epithelial barrier properties and differentiation. Processes/gene expression required for cervical ripening are distinct from those important in latter phases of cervical remodeling and highlight the importance of timing of tissue collection for understanding the molecular mechanisms of cervical ripening.

Uterine fibroids are composed of altered collagen fibrils and represent an arrested response to injury-initiating fibrosis. In many tissues, TSP-1 is secreted by adult macrophages and monocytes upon wounding and is involved in the activation of transforming growth factor β. In the absence of TSP-1, the orchestrated process of wound healing is impaired. The authors obtained tissue from the edge and center of fibroids at the time of hysterectomy and compared them with adjacent myometrium. The pattern of TSP-1 and TSP-2 expression was correlated to that of COL1A1 and COL3A1. Collagen and hydroxyproline were increased in fibroids. Thrombospondin-1 was consistently underexpressed in both the edge and center of the fibroids, while COL1A1 and COL3A1 were consistently overexpressed. However, TSP-2 was inconsistently expressed. These findings lead to the conclusion that the underexpression of TSP-1 may contribute to the overall development of uterine fibroids.