[Vaginal delivery of bi-scarred uterus].

Despite awareness of obstetricians to the constant increase in the number of caesarean sections in recent years, certain dogmas concerning uterine scar still persist in our practices and influence clinical decisions. Fear of a uterine scar rupture, a major obstetric complication, is always in mind. As for bi-uterine scar, it was considered, until recently in Belgium, as a full and definitive indication against an attempted vaginal delivery.

[Involvement of matrix metalloproteinases in obstetrics: from implantation to delivery].

Matrix metalloproteinases, which remodel the extracellular matrix, are involved in all physiological and pathophysiological processes. In particular, they contribute to the success of a pregnancy: from embryo implantation in the endometrium to uterine cervical ripening and uterine involution. A misregulation of their expression and/or of their activity is observed in two major diseases in pregnancy such as spontaneous abortion and preeclampsia.

Galactose alpha 1-3 galactose and anti-alpha galactose antibody in normal and pathological pregnancies.

The galactose alpha 1-3 galactose (Gal alpha 1-3 Gal) residue is a carbohydrate widely distributed in many non-human mammals. Since Gal alpha 1-3 Gal residues are described on the cell surface of tumor cells, we have examined the possibility of their expression on human trophoblastic cells at different stages of placental implantation and in various pregnancy-associated conditions. Using immunohistochemical methods, Gal alpha 1-3 Gal was demonstrated on interstitial and vascular trophoblast during pregnancy.

Reconstituted basement membrane matrix stimulates interstitial procollagenase synthesis by human fibroblasts in culture.

Synthesis of interstitial collagenase by human fibroblasts was compared when cultured on plastic, in the presence or absence of soluble laminin, on a type I collagen gel and on a gel of basement membrane components (matrigel). Fibroblasts cultured on matrigel or on type I collagen gel displayed an increase in the steady-state levels of mRNA for interstitial procollagenase that was proportional to its enzymatic activity. Laminin, the main component of matrigel, had no effect on the interstitial collagenase synthesis by fibroblasts.

Type IV and interstitial collagenolytic activities in normal and malignant trophoblast cells are specifically regulated by the extracellular matrix.

Type IV and interstitial collagenolytic activities were compared in human malignant and normal trophoblast cells cultured on plastic, in presence or absence of laminin in solution, on matrigel (a gel of basement membrane components) and on type I collagen gel. Laminin highly stimulated the type IV collagenolytic activity but not the interstitial collagenolytic activity, in malignant trophoblast cells. This glycoprotein had no effect on the interstitial collagenolytic activity and doubled the type IV collagenolytic activity in normal trophoblast cells.

Laminin and type III procollagen peptide in human preovulatory follicular fluid.

The levels of laminin P1 fragment, a marker of basement membrane, and of the aminoterminal sequence of type III procollagen, a marker of interstitial connective tissue, were measured in human preovulatory follicular fluids. The concentrations of these peptides correlated with progesterone levels but not with those of estradiol or testosterone. Immunocytochemical studies confirmed the remodeling of the perifollicular basement membrane and interstitial matrix during oocyte maturation.

Analysis of tridimensional mixed cultures of mouse B16 melanoma cells and 3T3 fibroblasts.

The interactions between invasive malignant cells and normal fibroblastic cells were studied in a cellular spheroid model in vitro. Murine B16 melanoma cells (previously cultured in monolayer for a short period) and 3T3 mouse fibroblasts (greater than or equal to 130 passages in monolayers) were cultured under tridimensional conditions (pure or mixed spheroids). As compared to pure 3T3 or mixed spheroids, B16 spheroids were smaller and characterized by a higher proliferation rate, a lower degree of necrosis, and a less abundant extracellular matrix.

[The mouse B16 melanoma in a 3-dimensional culture].

Multicellular spheroids composed of mouse B16 melanoma cells have been prepared in non agitated culture on solid agar. Cells present frequent contacts and an extracellular matrix appears during cultivation (up to 2 months in agitated suspension); it contains laminin, fibronectin and collagen I, III and IV. Cellular differentiation takes place inside these spheroids (melanogenesis progressively increases), but a relatively intense cell proliferation rate is also maintained.