Bone-matrix mineralization dampens integrin-mediated mechanosignalling and metastatic progression in breast cancer.

In patients with breast cancer, lower bone mineral density increases the risk of bone metastasis. Although the relationship between bone-matrix mineralization and tumour-cell phenotype in breast cancer is not well understood, mineralization-induced rigidity is thought to drive metastatic progression via increased cell-adhesion forces. Here, by using collagen-based matrices with adjustable intrafibrillar mineralization, we show that, unexpectedly, matrix mineralization dampens integrin-mediated mechanosignalling and induces a less proliferative stem-cell-like phenotype in breast cancer cells. In mice with xenografted decellularized physiological bone matrices seeded with human breast tumour cells, the presence of bone mineral reduced tumour growth and upregulated a gene-expression signature that is associated with longer metastasis-free survival in patients with breast cancer. Our findings suggest that bone-matrix changes in osteogenic niches regulate metastatic progression in breast cancer and that in vitro models of bone metastasis should integrate organic and inorganic matrix components to mimic physiological and pathologic mineralization.

A combined compression molding, heating, and leaching process for fabrication of micro-porous poly(ε-caprolactone) scaffolds.

Biomaterial scaffolds have been increasingly used for tissue engineering applications as well as three dimensional (3D) cell culture models. Herein, we report a simple procedure combining compression molding, heating, and leaching methods for the fabrication of 3D micro-porous poly(ε-caprolactone) (PCL) biomaterial scaffolds. In this procedure, PCL micro particles are mixed with NaCl of defined sizes and compression molded, followed by heating and subsequent leaching of NaCl particles. This technique eliminates the gas foaming method, which is commonly used in the fabrication of PCL scaffolds. Process and scaffold parameters (i.e., heating time, NaCl concentration, and NaCl particle size) were varied and analyzed to determine their impact on the overall scaffold structural and mechanical properties. An increase in NaCl particle size led to an increase in pore area but did not significantly impact the mechanical properties of the scaffolds. Additionally, NaCl concentration did not show a significant effect on pore area, but considerably impacted the mechanical properties, water absorption capacity and porosity of the scaffolds. Variations in the heating time did not have an effect in the pore area, porosity, water absorption capacity or mechanical properties of the scaffolds. We also demonstrated the ability of these scaffolds to support the proliferation of breast cancer cells. Overall, these results elucidated structure-property relationships in the fabricated micro-porous PCL scaffolds. Further, this procedure could be potentially scaled up for the fabrication of micro-porous PCL scaffolds.