Engineer a pre‐metastatic niched microenvironment to attract breast cancer cells by utilizing a 3D printed polycaprolactone/nano‐hydroxyapatite osteogenic scaffold – An in vitro model system for proof of concept

Abstract

Breast cancer bone metastasis is not a random process. It is affected by the local microenvironment which determines the propensity of cancer cells to invade and colonize into the secondary sites. This microenvironment is termed a pre-metastatic niche. With the flexibility to incorporate different biofactors, tissue-engineering scaffolds provide an advantageous environment to promote "designed" osteogenesis that may mimic the bony pre-metastatic niche. In the current study, designed polycaprolactone (PCL) scaffolds enriched with nano-hydroxyapatite (nHA) were fabricated through three-dimensional (3D) printing. Subsequently, human mesenchymal stem cells (hMSCs) were seeded onto PCL-nHA scaffolds for osteogenic differentiation to establish the pre-metastatic niched microenvironment. Furthermore, transwell migration assay was used to investigate recruitment of MDA-MB-231, MCF-7, and MDA-MB-453 breast cancer cells to the osseous PCL-nHA scaffolds. Our results showed that the mRNA levels of alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and osteocalcin (OCN) of hMSCs on the PCL-nHA scaffolds were dramatically increased compared those with the PCL scaffolds (control) at day 7, 14, and 28. Meanwhile, the migration analysis showed that the higher maturation of osteogenesis and bone metabolism collectively contributed to the creation of a more favorable niched site for the cancerous invasion. Moreover, one of the hypothesized key mediators for the promoted migration, CXCL12, was confirmed using an assay of antagonist LIT-927. This early study demonstrated that a designed tissue engineering scaffold can be utilized to create a bone-mimicking environment that serves as a novel platform to recapitulate the pre-metastatic niche and help interrogate the scheme of bone metastasis by breast cancer.

Current Advances in the Use of Tissue Engineering for Cancer Metastasis Therapeutics

“…Polycaprolactone (PCL) scaffolds with dispersed HAP have been fabricated using 3D printing to create bone-like models. This in vitro model is used to demonstrate the migration of MDA-MB-231, MCF-7, and MDA-MB-453 breast cancer cells toward the bone [ 65 , 66 ]. The 3D-printed scaffolds made of PCL infiltrated with a piezoceramic barium titanate (BaTiO3) were used to fabricate bone, specifically for load-bearing applications [ 64 ].…”

Evaluating material-driven regeneration in a tissue engineered human in vitro bone defect model

“…While bone tissue engineering strategies have already been successfully applied for the creation of in vitro models for bone marrow Abbreviations: SF, silk fibroin; hBMSCs, human bone marrow-derived mesenchymal stromal cells; HUVECs, human umbilical vein endothelial cells; μCT, micro- [16], bone metastasis [17], woven bone [18] and bone remodeling [19], the development of human in vitro bone defect models for biomaterial testing is rarely explored [14,15]. A tissue engineered defect model has previously been proposed, where authors created defects in silk fibroin (SF) scaffolds, seeded scaffolds with human bone marrow-derived mesenchymal stromal cells (hBMSCs), and studied tissue growth and mineralization in the defect area upon osteogenic differentiation [20].…”

Evaluating material-driven regeneration in a tissue engineered humanin vitrobone defect model

“…For the creation of such in vitro models, traditional bone tissue engineering strategies can be applied [15]. While bone tissue engineering strategies have already been successfully applied for the creation of in vitro models for bone marrow [16], bone metastasis [17], woven bone [18] and bone remodeling [19], the development of human in vitro bone defect models for biomaterial testing is rarely explored [14,15]. A tissue engineered defect model has previously been proposed, where authors created defects in silk fibroin (SF) scaffolds, seeded scaffolds with human bone marrow-derived mesenchymal stromal cells (hBMSCs), and studied tissue growth and mineralization in the defect area upon osteogenic differentiation [20].…”