Biology subjects

Tiffany, A. S.

Publications and source records attributed to Tiffany, A. S..

3 recordsLinked to original sources

bioRxiv2026

TUMOR HETEROGENEITY AND STEMNESS CAN BE SHAPED BY MECHANO-STRUCTURAL PARAMETERS IN OSTEOSARCOMA

Chemoresistance and recurrence of osteosarcoma (OS) can be attributed to a subpopulation of OS cells known as OS Cancer Stem-like Cells (OS-CSCs). We hypothesized that certain mechano-structurally distinct niches within the bone and tumor might be more conducive to OS-CSC formation. Using biomaterial-based 3D scaffolds of distinct structural and mechanical properties (anisotropic soft [~]10 kPa vs isotropic stiff [~]35 kPa), we discovered that OS cells growing in softer, anisotropic scaffolds were rounder, softer, had higher stemness gene expression, showed increased chemoresistance to doxorubicin and cisplatin, and were more tumorigenic in vivo. Mechanistically, biological reprogramming of OS cells on these scaffolds occurred through niche-driven transcriptional changes and differences in chemoresistance-associated epigenetic pathways. Our study showed that a softer, anisotropic niche is more conducive for maintaining OS-CSCs and these findings could be translated to designing therapeutic strategies targeting heterogeneous tumor populations or modifying the microarchitecture to reduce CSC-favoring niches.

cancer biology↗

bioRxiv2020

Freeform printing of heterotypic tumor models within cell-laden microgel matrices

The tissue microenvironment is comprised of a complex assortment of multiple cell types, matrices, membranes and vessel structures. Emulating this complex and often hierarchical organization in vitro has proved a considerable challenge, typically involving segregation of different cell types using layer-by-layer printing or lithographically patterned microfluidic devices. Bioprinting in granular materials is a new methodology with tremendous potential for tissue fabrication. Here, we demonstrate the first example of a complex tumor microenvironment that combines direct writing of tumor aggregates, freeform vasculature channels, and a tunable macroporous matrix as a model to studying metastatic signaling. Our photocrosslinkable microgel suspensions yield local stiffness gradients between particles and the intervening space, while enabling the integration of virtually any cell type. Using computational fluid dynamics, we show that removal of a sacrificial Pluronic ink defines vessel-mimetic channel architectures for endothelial cell linings. Pairing this vasculature with 3D printing of melanoma aggregates, we find that tumor cells within proximity migrated into the prototype vasculature. Together, the integration of perfusable channels with multiple spatially defined cell types provides new avenues for modelling development and disease, with scope for fundamental research and drug development.

bioengineering↗

bioRxiv2020

Stiffness of Nanoparticulate Mineralized Collagen Scaffolds Triggers Osteogenesis via Mechanotransduction and Canonical Wnt Signaling

The ability of the extracellular matrix (ECM) to instruct progenitor cell differentiation has generated excitement for the development of materials-based regenerative solutions. We previously described a nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) material capable of inducing in vivo skull regeneration approaching 60% of the biomechanical properties of native calvarium without exogenous growth factors or ex vivo progenitor cell-priming, suggesting promise as a first-generation material for skull regeneration. Here, we evaluated the contribution of titrating stiffness to osteogenicity by comparing non-crosslinked (NX-MC) and crosslinked (MC) forms of MC-GAG. While both materials were osteogenic, MC demonstrated an increased expression of osteogenic markers and mineralization compared to NX-MC. Both materials were capable of autogenously activating the canonical bone morphogenetic protein receptor (BMPR) signaling pathway with phosphorylation of Smad1/5 (small mothers against decapentaplegic-1/5). However, unlike NX-MC, hMSCs cultured on MC demonstrated significant elevations in the major mechanotransduction mediators YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif) expression coincident with {beta}-catenin activation in the canonical Wnt signaling pathway. Inhibition of YAP/TAZ activation reduced osteogenic marker expression, mineralization, and {beta}-catenin activation in MC with a much lesser of an effect on NX-MC. YAP/TAZ inhibition also resulted in a reciprocal increase in Smad1/5 phosphorylation as well as BMP2 expression. Our results indicate that increasing MC-GAG stiffness induces osteogenic differentiation via the mechanotransduction mediators YAP/TAZ and the canonical Wnt signaling pathway, whereas the canonical BMPR signaling pathway is activated in a manner independent of mechanical cues.

bioengineering↗