Novel insights from 3D models: the pivotal role of physical symmetry in epithelial organization

Abstract

3D tissue culture models are utilized to study breast cancer and other pathologies because they better capture the complexity of in vivo tissue architecture compared to 2D models. However, to mimic the in vivo environment, the mechanics and geometry of the ECM must also be considered. Here, we studied the mechanical environment created in two 3D models, the overlay protocol (OP) and embedded protocol (EP). Mammary epithelial acini features were compared using OP or EP under conditions known to alter acinus organization, i.e. collagen crosslinking and/or ErbB2 receptor activation. Finite element analysis and active microrheology demonstrated that OP creates a physically asymmetric environment with non-uniform mechanical stresses in radial and circumferential directions. Further contrasting with EP, acini in OP displayed cooperation between ErbB2 signalling and matrix crosslinking. These differences in acini phenotype observed between OP and EP highlight the functional impact of physical symmetry in 3D tissue culture models.

Spatial distributions of pericellular stiffness in natural extracellular matrices are dependent on cell-mediated proteolysis and contractility

“…MMP mediated matrix degradation has been shown to be critical in processes including angiogenesis[15,16], cancer metastasis [17], or skeletal formation[18]. Thus, both cytoskeletal contractility and MMP activity are logical targets to explore the role of a cell in establishing or maintaining its pericellular stiffness, which we have shown can be significantly stiffer than values reported by bulk rheology [19–21] and are consistent in order-of-magnitude to stiffness reported by other groups using AMR in type I collagen[22], Matrigel, hyaluronic acid, and zebrafish in vivo [23]. In earlier studies, we used AMR to discover that during capillary morphogenesis, the pericellular space surrounding the tip of a sprouting capillary had increased stiffness as compared to distal regions[24].…”

“…Even within synthetic ECM constructs, specifically those with sites susceptible to cell-mediated degradation, pericellular mechanical properties are unknown unless measured directly, as has been recently noted[47]. Our method is generalizable to many tissue engineering systems because it is independent of ECM composition and cell type[19–21,24,48–50]. AMR is ultimately limited by the minimum detectable bead displacement as well as maximum bead density, which is not only restricted by pore structure and bead size, but can also influence ECM properties with excessive loading.…”

In Vitro 3D Cultures to Reproduce the Bone Marrow Niche

“…Hydrogel, scaffold Breast, prostate, osteosarcoma (63)(64)(65) Chitosan-alginate Scaffold Prostate, glioblastoma, hepatocellular carcinoma (66,67) Hyaluronic acid Scaffold, hydrogel Renal cell carcinoma, MM (68,69) Bacterial nanocellulose Scaffold, hydrogel Neuroblastoma, osteosarcoma, prostate, renal cancer, breast (70,71) Native ECM Scaffold MM, breast (72,73) ECM/cartilaginous matrix/Matrigel Scaffold, hydrogel Breast (74) Chitosan (with or without HA or collagen) Scaffold Breast (75) Cell sheets over medical-grade polycaprolactone-tricalcium phosphate scaffold prostate (76) Synthetic materials Poly(ethylene) glycol Hydrogel Breast, prostate (77)(78)(79) Poly(ε-caprolactone) Hydrogel Breast, prostate, osteosarcoma, Ewing sarcoma (80)(81)(82) Poly(amino acid-)-based polymers Hydrogel Osteosarcoma (83) PLG (nonmineralized) and PLG mineralized with HA Scaffold Breast (84) Adapted with permission from Sitarski and colleagues. (33) BM = bone marrow; ECM = extracellular matrix; HA = hydroxyapatite; MM = multiple myeloma; PLG = poly(lactide-co-glycolide).…”

In Vitro Microscale Models for Embryogenesis

“…In addition, these systems can be used to mimic spatiotemporal organizations and chemical signals associated with stem cell niche, physiological fluid flow, and other natural tissue-like properties. [13] The high-throughput nature of micro-technologies allows for efficient teratogen screening and full characterization of teratoxicity.…”