Biology subjects

Estroff, L. A.

Publications and source records attributed to Estroff, L. A..

6 recordsLinked to original sources

bioRxiv2026

Directional bone matrix mineralization in the CAM assay is governed by vascular integration and matrix remodeling

Bone matrix mineralization plays an important role in maintaining bone health but is a highly dynamic process for which few physiologically relevant model systems exist. The chorioallantoic membrane (CAM) assay is one such assay and has been used to study biomineralization; however, the mechanisms controlling mineral deposition in the CAM assay remain poorly understood. Here, we implanted decellularized, organic bone matrices onto the CAM and investigated their mineralization using a combination of micro-computed tomography, Raman spectroscopy, scanning electron microscopy, and histochemistry. These studies revealed increased mineralization and microvessel density on the shell-facing interface of the implanted matrices, while their embryo-facing counterpart lacked mineralization but was densely infiltrated by cells. Seeding organic bone matrices with mesenchymal stromal cells (MSCs) prior to CAM-implantation prevented mineralization by altering matrix micro- and nanostructure and limiting vessel integration. Collectively, our results suggest that mineral precursors from the eggshell and vasculature combine to mineralize organic bone matrix in the CAM assay, while proteolytic remodeling by invaded or implanted stromal cells inhibits that process. Our findings provide critical new insights into the interplay between acellular and cellular drivers of bone matrix mineralization, and will inform future studies of biomineralization using the CAM assay.

bioengineering↗

bioRxiv2025

A multiscale physicochemical characterization of melanin-based feather coloration in the rapid Capuchino Seedeater radiation

Melanin-based plumage coloration in birds is shaped by pigment composition as well as melanosome morphology and distribution, however, the ways in which these factors together modulate observable color remain poorly understood. We investigate this relationship in the Capuchino Seedeaters (genus Sporophila), whose recent, rapid radiation driven by sexual selection resulted in 12 species with diverse coloration patterns. Using scanning electron microscopy (SEM) and micro-computed tomography ({micro}CT), combined with a novel application of Fontana-Masson stain to image melanosomes at high resolution, we characterize melanosome distribution and morphology in several variably colored plumage patches across Capuchino species. Melanosome morphologies followed patch-specific patterns that did not directly correlate with coloration: crown feather melanosomes were larger, more elongated, and had greater percent eumelanin content than those in belly, throat, or dorsum/rump patches. We also observed that dorsal patches had more total melanin than ventral ones, with pigment and coloration patterns suggesting possible signaling and photoprotective roles. More generally, we show how the patch-specific coloration of male Capuchinos is accompanied by differences in melanosome morphology and melanin composition and abundance. Our work highlights the challenges that remain in understanding how the nanoscale mechanisms of melanin-based pigmentation translate into macroscale plumage coloration.

evolutionary biology↗

bioRxiv2025

Assessing cellular metabolic dynamics with NAD(P)H fluorescence polarization imaging

Altered metabolism enables adaptive advantages for cancer, driving the need for improved methods for non-invasive long-term monitoring of cellular metabolism from organelle to population level. Here we present two-photon steady-state fluorescence polarization ratiometric microscopy (FPRM), a label-free imaging method that uses nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) autofluorescence as a functional readout of cellular metabolism. The method is simple to implement and operates an order of magnitude faster than the NAD(P)H-fluorescence lifetime imaging microscopy (FLIM) imaging modality, reducing cytotoxic stress while providing long-term monitoring capacity. FPRM enables high-resolution dynamic tracking of NAD(P)H signals with subcellular details and we have established a set of instrument-independent ratiometric parameters that correlates NAD(P)H signals with metabolic status during pharmaceutical and environmental perturbations. We further integrated FPRM readouts with other parameters such as cell shape and migration on 2D and 3D collagen matrices, demonstrating the techniques versatility across bioengineered platforms for cancer metabolism research.

biophysics↗

bioRxiv2024

Bone mineral density affects tumor growth by shaping microenvironmental heterogeneity

Breast cancer bone metastasis is the leading cause of mortality in patients with advanced breast cancer. Although decreased mineral density is a known risk factor for bone metastasis, the underlying mechanisms remain poorly understood because studying the isolated effect of bone mineral density on tumor heterogeneity is challenging with conventional approaches. Here, we investigate how bone mineral content affects tumor growth and microenvironmental complexity in vivo by combining single-cell RNA-sequencing with mineral-containing or mineral-free decellularized bone matrices. We discover that the absence of bone mineral significantly influences fibroblast and immune cell heterogeneity, promoting phenotypes that increase tumor growth and alter the response to injury or disease. Importantly, we observe that the stromal response to matrix mineral content depends on host immunocompetence and the murine tumor model used. Collectively, our findings suggest that bone mineral density affects tumor growth by altering microenvironmental complexity in an organism-dependent manner.

bioengineering↗

bioRxiv2024

Collagen mineralization decreases NK cell-mediated cytotoxicity of breast cancer cells via increased glycocalyx thickness

Skeletal metastasis is common in patients with advanced breast cancer, and often caused by immune evasion of disseminated tumor cells (DTCs). In the skeleton, tumor cells not only disseminate to the bone marrow, but also to osteogenic niches in which they interact with newly mineralizing bone extracellular matrix (ECM). However, it remains unclear how mineralization of collagen type I, the primary component of bone ECM, regulates tumor-immune cell interactions. Here, we have utilized a combination of synthetic bone matrix models with controlled mineral content, nanoscale optical imaging, and flow cytometry to evaluate how collagen type I mineralization affects the biochemical and biophysical properties of the tumor cell glycocalyx, a dense layer of glycosylated proteins and lipids decorating their cell surface. Our results suggest that collagen mineralization upregulates mucin-type O-glycosylation and sialylation by tumor cells, which increased their glycocalyx thickness while enhancing resistance to attack by Natural Killer (NK) cells. These changes were functionally linked as treatment with a sialylation inhibitor decreased mineralization-dependent glycocalyx thickness and made tumor cells more susceptible to NK cell attack. Together, our results suggest that interference with glycocalyx sialylation may represent a therapeutic strategy to enhance cancer immunotherapies targeting bone-metastatic breast cancer.

cancer biology↗

bioRxiv2022

Biofunctional matrix models reveal mineral-dependent mechanoregulation of bone metastatic breast cancer

Bone metastasis is a leading cause of breast cancer-related deaths and often initiated by tumor cell dissemination to osteogenic niches. During new bone formation, osteoblasts first deposit osteoid, the collagen I-rich, unmineralized component of bone ECM, within which carbonated hydroxyapatite nanoparticles subsequently form. However, it remains elusive how bone matrix mineralization dictates tumor cell phenotype due in part to the lack of relevant model systems. Using biofunctional, collagen I-based bone matrix models with physiological, intrafibrillar mineralization, we show that mineralization inhibits proliferation, while inducing a stem-like phenotype in tumor cells. These changes were due to reduced mechanosignaling contradicting the conventional assumption that increased rigidity caused by mineralization stimulates metastatic progression. Our findings are translationally relevant as the presence of mineral reduced tumor growth in vivo and upregulated a gene signature that correlated with decreased patient mortality. Our results could help explain why decreased bone mineral density increases the risk for bone metastasis in patients and highlight that bone metastasis models should integrate organic and inorganic matrix components in a manner that mimics physiological mineralization.

bioengineering↗