Z47 - Seed and Soil: A 3D Model to Study Breast Cancer and Mesenchymal Stem Cell Interactions

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Fernanda Tamayo

Biomedical Engineering Student
University of California, Irvine
Chula Vista, California, United States

Co-Author(s)

Timothy Burg

Professor
University of Georgia
Athens, Georgia, United States

Last Author(s)

Karen Burg, PhD

Professor
University of Georgia
Athens, Georgia, United States

Co-Author(s)

RA

Rigsby Arnold

Biomedical Physiology Student
University of Georgia
Weitong Chen, MSc, PhD

Senior Research Associate
University Georgia
Athens , Georgia, United States

Introduction: : Breast cancer is the most commonly diagnosed cancer, where approximately 70% of all breast cancer metastasis cases involve bone tissue.1 Breast cancer bone metastasis (BCBM) typically originates within the bone marrow microenvironment, which is characterized by a high number of mesenchymal stem cells (MSCs) residing in the porous cavities of cancellous bone. Currently, the investigations of interactions between MSCs and breast cancer cells on 3D models are limited, with contradictory results (for example, MSCs stimulating versus MSCs suppressing breast cancer proliferation or tumor formation).2,3 In this study, 3D-printed scaffolds were developed with the micro-porous architecture of bone, in order to model the interactions within the cancellous bone microenvironment during the early stages of breast cancer metastasis, specifically focusing on the interaction between MSCs and MCF-7 breast cancer cells. The scaffolds were fabricated using polyethylene terephthalate glycol (PETG) and nano-hydroxyapatite (nHA), to mimic the chemical components of native bone. The purpose of this work was to create a reproducible, more bone-like environment, with physical features of porosity, to study MSC-breast cancer interactions.

Materials and

Methods: : The composite bone scaffolds were printed using a filament of 70wt% PETG (Polyethylene Terephthalate Glycol) and 30wt% nHA with average diameter of 1.65-1.85 mm. A PETG filament was used to print PETG scaffolds. Using a PRUSA MK4 3D Printer, cylindrical scaffolds were printed with the as-designed diameter of 10mm and height of 6mm. To mimic the porous geometries of cancellous bone, the scaffolds were printed with “gyroid” infill shapes and 40% infill density (60% porosity) to mimic the structure of healthy cancellous bone. Four groups of scaffolds were created (n=12 for each group): PETG scaffolds seeded with MSCs (group 1A), PETG scaffolds seeded with both MSCs and MCF-7s (group 1B), composite scaffolds (denoted as PETG-nHA) seeded with only MSCs (group 2A), and composite scaffolds seeded with both MSCs and MCF-7s (group 2B).

The surface of PETG-nHA scaffolds was treated with sodium hydroxide solution (pH=12, 15 mins) to expose the encapsulated HA nano-particles and improve hydrophilicity and cell-material interactions. Hydrophilicity and pore size were evaluated before and after treatment to ensure that the treatment did not affect pore size, while effectively modifying the hydrophilicity. Prior to seeding, MSCs and MCF-7s were fluorescently labeled with CellTracker™ Green and Red to allow visualization and quantification. Consequently, all scaffolds (groups 1A, 1B, 2A, and 2B) were seeded with 1×105 MSCs, groups 1B and 2B were subsequently seeded with 1×105 MCF-7s.

Results, Conclusions, and Discussions:: The PETG-nHA composite was successfully extruded into filaments and subsequently fabricated into scaffolds via 3D printing. The hydrophilicity, as measured by water contact angle (WCA), increased following the addition of nHA to PETG and increased further when the composite material was treated with sodium hydroxide (84.5 ± 3.1o vs. 79.4 ± 3.7 o vs. 70.7 ± 3.5 o, FIG. 1.). As hypothesized, the proliferation of MSCs on Day 7 was much higher in the composite material compared to the PETG only material (486 ± 127.5 vs 342.5 ± 57.5, arrow labeled “A” in FIG. 2.), supporting the theory that the addition of nHA and enhanced hydrophilicity improves cell proliferation. As expected, the proliferation of MCF-7s was significantly higher than that of MSCs, both in the PETG only material and the composite material (940 ± 93 cells vs. 343 ± 58 cells and 782 ± 94 cells vs. 486 ± 128 cells at Day 7 in FIG. 2). Interestingly, the PETG-nHA material supported lower MCF-7 cell proliferation than PETG (782 ± 94 cells vs 940 ± 93 cells as indicated by arrow labeled “B” in FIG. 2) when MSC numbers were higher, reinforcing the previously suggested concept that the MSCs have the potential to inhibit the proliferation of MCF-7s.4
The 3D printed, treated PETG-nHA scaffolds had high structure fidelity and hydrophilicity, and supported a higher number of MSCs compared to other materials used for bone modeling. The presence of MSCs may inhibit MCF-7 cell growth. To further understand the interaction between MSCs and MCF-7s on the tested substrate, future research will evaluate the impact of MCF-7s on the differentiation and mineralization of MSCs, which can provide a potential direction for clinical intervention in the early stages of breast cancer bone metastasis.

Acknowledgements and/or References (Optional): : 1. Brewer, T.M. et al. (2013). Chapter 11: Bone metastasis of breast cancer. In A. Ahmad (Ed.), Breast cancer metastasis and drug resistance (2nd Edition, pp. 105-129). Springer.
2. Zhu, W. et al. Engineering a biomimetic three-dimensional nanostructured bone model for breast cancer bone metastasis study. Acta Biomater. 14, 164–174 (2015).
3. Bartosh, T.J. et al. Cancer cells enter dormancy after cannibalizing mesenchymal stem/stromal cells (MSCs). Proc. Natl. Acad. Sci. U. S. A. 113, E6447–E6456 (2016).
4. Mirabdollahi, M. et al. Human Wharton’s jelly mesenchymal stem cells-derived secretome could inhibit breast cancer growth in vitro and in vivo. Iran. J. Basic Med. Sci. 23, 945–953 (2020).