Metastatic cancer spread to the skeleton is common and after the metastasis occurs, patient prognosis dramatically declines due to severe skeletal-related complications, including bone destruction ("osteolysis"). The goal of this project is to define for the first time how the mechanical signals arising from physical activity, which are the primary regulator of bone cell function and remodeling, regulate the bone metastatic cells that are exposed to the same signals.  This will be accomplished by pursuing three objectives: 1) Building a tissue-level multi-physics computational model of mechanical loading in a 3D bone mimetic scaffold. 2) Determining the cellular strains resulting from interactions between bone metastatic breast cancer cells and fluid flow and 3) defining a data-driven relationship between cellular strains and bone metastatic breast cancer cell osteolytic phenotype. The results will transform fundamental understanding of how tumor cells are regulated in the skeletal microenvironment with considerable potential to improve clinical management of the disease. Educational Impact will be achieved through increased educational opportunities in bioengineering at the undergraduate level, engage middle and high school underrepresented populations in bioengineering research at UMass, and active recruitment of graduate students from underrepresented groups to broaden participation in the field of bioengineering. This award is cofunded by the Computational Mathematics program in the Division of Mathematical Sciences through the BioMaPs program. This project seeks to define, for the first time, a mechano-regulatory algorithm that links metastatic cancer cell function and cellular deformations. The skeleton is the preferred site for metastasis in many cancers, including breast, prostate, lung, and kidney. After metastasis occurs, patient prognosis dramatically declines due to severe skeletal-related complications, including bone destruction (?osteolysis?). Mechanical signals arising from physical activity are the primary regulator of bone cell function and remodeling, and bone metastatic cells are also exposed to these signals; however, their role in metastasis in unclear because they are often ignored in studies of metastatic bone disease. Using breast cancer as our example case, our preliminary data shows that compression of bone metastatic tumor cells in a 3D bone mimetic scaffold altered their expression of genes that modify bone remodeling, supporting our hypothesis that skeletal mechanical signals are a fundamental regulator of tumor cell behavior. Here, we seek to systematically define the functional relationship between mechanical signals and bone metastatic cell function through development of an integrated in vitro 3D experimental and multi-physics, multi-scale computational platform. This project will benefit from collaboration between experts in engineered systems of in vitro loading and cancer biology as well as computational fluid-structure modeling. The Research Plan is presented as three objectives:  1) Build a tissue-level multi-physics computational model of mechanical loading in our 3D bone mimetic scaffold. Method: This objective will generate a "tissue-level" computational model including Finite Element and Computational Fluid Dynamic analysis to determine the internal stresses and strains of our bone scaffold undergoing compression and perfusion. MicroCT images of the scaffold will be converted to a discretized model, and estimated values of the induced flow velocities and the extracellular matrix strain within the scaffold will be calculated based on a one-way coupling method; 2) Determine the cellular strains resulting from interactions between bone metastatic breast cancer cells and fluid flow. Method: This objective will create a "cell-level" computational model of cellular deformations. The estimated values of internal flow velocity and tractions from Objective 1 are utilized as the boundary conditions for a fully-coupled Fluid-Structure Interaction algorithm, which will be used to model the interaction between the inter-scaffold fluid flow and cancer cells; 3) Define a data-driven relationship between cellular strains and bone metastatic breast cancer cell osteolytic phenotype. Method: This objective will result in a data-driven mechano-regulatory algorithm for bone metastatic breast cancer cells. First, the cellular response of tumor cells, cultured in our bone scaffold, under a range of imposed mechanical loading environments will be measured via expression of osteolytic genes. These results will be mathematically correlated to the cellular deformations from Objective 2 using multivariate statistical analysis.  The results of this project will transform our fundamental understanding of how tumor cells are regulated in the skeletal microenvironment with considerable potential to improve clinical management of the disease. The data collected from these studies will form the foundation for defining the role of mechanical stimulation during bone metastasis.  Educational Impact will be achieved through increased educational opportunities in bioengineering at the undergraduate level, engage middle and high school underrepresented populations in bioengineering research at UMass, and active recruitment of graduate students from underrepresented groups to broaden participation in the field of bioengineering.