Biology subjects

Tiffany, A.

Publications and source records attributed to Tiffany, A..

6 recordsLinked to original sources

bioRxiv2026

Multi-material biomaterial model of scaffold-defect integration at the wound margins

Critical-sized craniomaxillofacial (CMF) defects affect the skull, face, and jaw, arising from conditions such as cleft palate, oncologic resections, and high energy impacts, and due to their large size and irregular geometry, cannot heal naturally by the body, thus requiring surgery. The field of biomedical research has long recognized the need to develop higher order biomaterial model systems for improved disease characterization and translational therapeutic/material progress. There is, however, difficulty in developing these workflows at the scale of conventional two-dimensional cell culture screening systems while simultaneously approaching a level of complexity necessary to consider translation to in vivo animal models. Here, we describe a three-dimensional (3D), in vitro model system to investigate the impact of stromal cell migration from one microenvironment to another at a medium-throughput scale. Importantly, we demonstrate the ability of this workflow to be utilized as a screening tool for collagen-based biomaterial motifs of interest in promoting craniomaxillofacial bone defect repair. Taken together we provide a strategy for interpreting cell-to-cell, cell-to-material, and material-to-material interactions across a multidimensional spatiotemporal scale.

bioengineering↗

bioRxiv2026

Reciprocal macrophage-MSC crosstalk drives immunomodulatory and regenerative phenotypes in a mineralized collagen scaffold

Critical sized craniomaxillofacial bone defects do not heal naturally and often exhibit chronic inflammatory responses that restrict regeneration. It is increasingly apparent that biomaterials must facilitate dynamic crosstalk between immune cells, such as macrophages, and osteoprogenitors to resolve inflammation and accelerate regeneration. Here, we evaluate interactions between macrophages in a neutral (M0) or pro-inflammatory (M1) state with mesenchymal stem cells (MSCs) in a basal or licensed state within a mineralized collagen scaffold. We reveal that MSC-macrophage crosstalk influences significant changes in osteoprogenitor cell differentiation and immune cell polarization. Notably, crosstalk between MSCs and macrophages drives an early-stage inflammatory response, which enhances the immunomodulatory activity of MSCs via secretion of IL-6, an effect that is heightened for already licensed MSCs. The presence of macrophages in the co-cultures upregulated osteogenic (ALPL, BMP2, COL1A2, and RUNX2) and angiogenic genes (ANGPT1) in basal MSC groups. Further, MSC-macrophage interactions subsequently drive increased M2-like macrophage polarization as early as 7 days of culture, as indicated by surface marker expression. These findings show that biomaterial scaffolds can be leveraged as mediators of MSC-mediated immunomodulation with an emphasis on achieving early-stage pro-inflammatory phenotypes that drive subsequent macrophage polarization and markers of increased regenerative potency.

bioengineering↗

bioRxiv2025

Identification of Injury-Response State Determinants in Glioblastoma Stem Cells

Glioblastoma (GBM) is a common and highly lethal type of primary brain tumor in adults. Therapeutic failure is partly attributed to a fraction of Glioblastoma Stem Cells (GSCs) that show high levels of heterogeneity and plasticity. GSCs exist in a transcriptional gradient between two states: Developmental (Dev) and Injury Response (IR) in which IR-GSCs exhibit more invasive behaviors. While previous studies have identified fitness genes in GSCs, the genes required to establish and maintain the Dev and IR states remain poorly defined. To identify the regulators of the IR GSC state, we performed a phenotypic genome-wide CRISPR-Cas9 knockout (KO) screen in patient-derived GSCs based on cell surface expression of the IR marker CD44. Notably, we found that perturbations of the histone acetyltransferase EP300 in IR GSCs led to decreased CD44 cell surface expression, significant downregulation of gene expression signatures associated with the IR state, and to decreased self-renewal and invasion. Furthermore, genetic targeting of Ep300 in a mouse GBM model delayed tumor initiation and/or progression. Collectively, our results establish EP300 as a regulator of the IR state in GSCs and provide a mechanistic basis for its therapeutic targeting in GBM. SignificanceA genome-wide phenotypic CRISPR-Cas9 screen in a patient-derived Glioblastoma Stem Cell line identified the genes required to maintain the Injury-Response cellular state, with a focus on the histone acetyl transferase gene EP300. This study suggests how therapeutic targeting of cellular state could reduce the aggressiveness of GBM tumors.

cancer biology↗

bioRxiv2023

DONOR VARIABILITY IN HUMAN MESENCHYMAL STEM CELL OSTEOGENIC RESPONSE AS A FUNCTION OF PASSAGE CONDITIONS AND DONOR SEX

Contemporary tissue engineering efforts often seek to use mesenchymal stem cells (MSCs) due to their potential to differentiate to various tissue-specific cells and generate a pro-regenerative secretome. While MSC differentiation and therapeutic potential can differ as a function of matrix environment, it may also be widely influenced as a function of donor-to-donor variability. Further, effects of passage number and donor sex may further convolute the identification of clinically effective MSC-mediated regeneration technologies. We report efforts to adapt a well-defined mineralized collagen scaffold platform to study the influence of MSC proliferation and osteogenic potential as a function of passage number and donor sex. Mineralized collagen scaffolds broadly support MSC osteogenic differentiation and regenerative potency in the absence of traditional osteogenic supplements for a wide range of MSCs (rabbit, rat, porcine, human). We obtained a library of bone marrow and adipose tissue derived stem cells to examine donor-variability of regenerative potency in mineralized collagen scaffolds. MSCs displayed reduced proliferative capacity as a function of passage duration. Further, MSCs showed significant sex-based differences. Notably, MSCs from male donors displayed significantly higher metabolic activity and proliferation while MSCs from female donor displayed significantly higher osteogenic response via increased alkaline phosphate activity, osteoprotegerin release, and mineral formation in vitro. Our study highlights the essentiality of considering MSC donor sex and culture expansion in future studies of biomaterial regenerative potential.

bioengineering↗

bioRxiv2022

Evaluation of P. aeruginosa attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis

The design of biomaterials to regenerate bone is likely to increasingly require modifications that reduce bacterial attachment and biofilm formation as infection during wound regeneration can significantly impede tissue repair and typically requires surgical intervention to restart the healing process. Here, we investigate the ability of a mineralized collagen biomaterial to natively resist infection as well as how the addition of manuka honey affects bacterial colonization and mesenchymal stem cell osteogenesis. We incorporate manuka honey into these scaffolds via either direct fabrication into the scaffold microarchitecture or via soaking the scaffold in a solution of Manuka honey after fabrication. Direct incorporation results in a change in the surface characteristics and porosity of mineralized collagen scaffolds. Soaking scaffolds in honey concentrations greater than 10% had significant negative effects on mesenchymal stem cell metabolic activity but soaking or incorporating 5% honey had no impact on endothelial cell tube formation. Soaking and incorporating 5% honey into scaffolds reduced metabolic activity of mesenchymal stem cells, however, soaking 5% honey into scaffolds increased calcium and phosphorous mineral formation, osteoprotegerin release, and alkaline phosphatase activity. The addition of manuka honey did not prevent P. aeruginosa attachment but may be able to limit attachment of other common wound-colonizing bacteria. Overall, our results demonstrate the potential for soaking mineralized collagen scaffolds in 5% manuka honey to increase osteogenesis of mesenchymal stem cells.

bioengineering↗

bioRxiv2020

Sequential sequestrations increase the incorporation and retention of multiple growth factors in mineralized collagen scaffolds

Trauma induced injuries of the mouth, jaw, face, and related structures present unique clinical challenges due to their large size and complex geometry. Growth factor signaling coordinates the behavior of multiple cell types following an injury, and effective coordination of growth factor availability within a biomaterial can be critical for accelerating bone healing. Mineralized collagen scaffolds are a class of degradable biomaterial whose biophysical and compositional parameters can be adjusted to facilitate cell invasion and tissue remodeling. Here we describe the use of modified simulated body fluid treatments to enable sequential sequestration of bone morphogenic protein 2 and vascular endothelial growth factor into mineralized collagen scaffolds for bone repair. We report the capability of these scaffolds to sequester growth factors from solution without additional crosslinking treatments and show high levels of retention for individual and multiple growth factors that can be layered into the material via sequential sequestration steps. Sequentially sequestering growth factors allows prolonged release of growth factors in vitro and suggests the potential to improve healing of large-scale bone injury models in vivo. Future work will utilize this sequestration method to induce cellular activities critical to bone healing such as vessel formation and cell migration.

bioengineering↗