Modelling uterine fibroids

Uterine fibroids or leiomyomas are tumors of the uterus which result from the excessive deposition of scar-like fibrous tissue into the myometrial smooth muscle. Although they are not metastatic, these growths cause chronic debilitating conditions in around 70-80% of reproductive aged women. Treatment options for this common pathology are extremely limited and often involve invasive surgery or unwanted side effects. Hence there is an urgent need for the development of better treatment options for this fibrotic disease. To test new treatments, a model system with which to investigate aspects of fibroid pathogenesis and evaluate treatment strategies is needed. Current models are limited and predominantly involve monolayer cell cultures. However such cultures do not facilitate the deposition of a collagenous extracellular matrix; a critical component of fibroids. This study investigates the potential of a technique known as macromolecular crowding, to model fibroid pathology. In this technique, large space-occupying molecules are incorporated into the culture medium, facilitating the correct processing and deposition of collagen by cells in culture. This technique has been investigated in cultures of fibroblasts and mesenchymal stem cells. However its impact on collagen deposition by myometrial smooth muscle cells is unknown. By immunocytochemical staining, the current study demonstrates that like fibroblasts, myometrial smooth muscle cells respond to crowded culture conditions by increasing production of type I collagen. This is mediated by enhanced processing of procollagen, enabling the secretion and deposition of cross-linked collagen, thus modelling the most important and symptomatic feature of fibroid pathology. Unlike monolayer cultures, the formation of an extracellular matrix in this culture system enables investigation of cell-matrix interactions. Indeed the current study suggests that the extracellular matrix produced in these cultures may interact with cell surface receptors to influence alignment of the actin cytoskeleton. By this means, these cultures may facilitate the process of mechanotransduction thought to be involved in fibroid pathogenesis. Furthermore, culturing myometrial cells under crowded conditions was shown to modulate the bioavailability of endogenous growth factors, further indicating that this methodology may prove useful in studying fibroid pathology.