The biological roles of laminin and type IV collagen in human endometrial stromal tissues were investigated by the evaluation of the expression levels in human endometrial tissues using immunohistochemistry. In addition, normal human endometrial stromal cells were cultured in vitro on laminin- or type IV collagen-coated plates and subjected to cytological analyses. Cyclic production of laminin and type IV collagen were detected and the two productions were significantly increased in late proliferative and late secretory endometrial stromal cells. Unstimulated endometrial stromal cells proliferated with specific growth structures that varied depending on the extracellular matrix component coated on the culture plates. The expression levels of integrin subunits on endometrial stromal cells were sufficiently enhanced by 8Br-cAMP treatment to mask any differences in the growth structures induced by the extracellular matrix components. 8Br-cAMP-stimulating stromal cells exhibited significant survival on laminin-coated plates, while 8Br-cAMP-deprived stromal cells, after 8Br-cAMP stimulation, showed significant survival on type IV collagen-coated plates. In conclusion, human endometrial stromal cells produce laminin and type IV collagen, and these productions are possibly regulated by ovarian estrogen and progesterone. Human endometrial stromal cells specifically bind to laminin and type IV collagen via integrins, and regulate endometrial stromal cell structures, viability and differentiation. Thus, laminin and type IV collagen may autoregulate human endometrial stromal remodeling during the menstrual cycle in an autocrine and paracrine fashion.

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