In Vitro Vascularized Tumor Platform for Modeling Tumor-Vasculature Interactions of Inflammatory Breast Cancer

Inflammatory breast cancer (IBC), a rare form of breast cancer associated with increased angiogenesis and metastasis, is largely driven by tumor-stromal interactions with the vasculature and the extracellular matrix (ECM). However, there is currently a lack of understanding of the role these interactions play in initiation and progression of the disease. In this study, we developed the first three-dimensional, in vitro, vascularized, breast tumor platform to quantify the spatial and temporal dynamics of tumor-vasculature and tumor-ECM interactions specific to IBC. Platforms consisting of collagen type 1 ECM with an endothelialized blood vessel were cultured with IBC cells, MDA-IBC3 (HER2+) or SUM149 (triple negative), and for comparison to non-IBC cells, MDA-MB-231 (triple negative). An acellular collagen platform with an endothelial blood vessel served as control. SUM149 and MDA-MB-231 platforms exhibited a significantly (p<0.05) higher vessel permeability and decreased endothelial coverage of the vessel lumen compared to the control. Both IBC platforms, MDA-IBC3 and SUM149, expressed higher levels of VEGF (p<0.05) and increased collagen ECM porosity compared to non-IBC MDA-MB-231 (p<0.05) and control (p<0.01) platforms. Additionally, unique to the MDA-IBC3 platform, we observed progressive sprouting of the endothelium over time resulting in viable vessels with lumen. The newly sprouted vessels encircled clusters of MDA-IBC3 cells replicating a feature of in vivo IBC. The IBC in vitro vascularized platforms introduced in this study model well-described in vivo and clinical IBC phenotypes and provide an adaptable, high throughout tool for systematically and quantitatively investigating tumor-stromal mechanisms and dynamics of tumor progression.

💡 Research Summary

Inflammatory breast cancer (IBC) is a highly aggressive breast cancer subtype characterized by rapid angiogenesis, extensive lymphovascular invasion, and poor prognosis. Existing pre‑clinical models—2‑D monolayers, xenografts, and simple 3‑D spheroids—fail to recapitulate the dynamic tumor‑vascular microenvironment of IBC, especially the continuous endothelial barrier and physiologic flow conditions. To address this gap, Gadde et al. engineered a novel three‑dimensional, microfluidic, vascularized tumor platform that integrates a collagen‑I extracellular matrix (ECM) with a perfusable, endothelialized lumen. Human breast cancer cell lines representing HER2⁺ IBC (MDA‑IBC3), triple‑negative IBC (SUM149), and non‑IBC triple‑negative (MDA‑MB‑231) were embedded at 1 × 10⁶ cells mL⁻¹ within a 7 mg mL⁻¹ collagen gel. A 22‑gauge needle created a central channel subsequently seeded with 2 × 10⁵ mKate‑labeled TIME (telomerase‑immortalized microvascular endothelial) cells, forming a continuous vessel. A graded shear‑stress protocol (0.01 → 0.1 → 1 dyn cm⁻² over 78 h) established a confluent, aligned endothelium that mimics physiological wall shear stress.

Four experimental groups were compared: (1) endothelial‑only control, (2) TIME + MDA‑MB‑231, (3) TIME + SUM149, and (4) TIME + MDA‑IBC3. The authors quantified (i) endothelial morphology and junctional integrity via PECAM‑1/F‑actin immunofluorescence, (ii) vessel permeability using 70 kDa Oregon‑Green dextran, (iii) ECM porosity by scanning electron microscopy, and (iv) angiogenic cytokine secretion (VEGF) by ELISA. Key findings include:

• Both IBC lines (MDA‑IBC3, SUM149) produced significantly higher VEGF levels than the non‑IBC line (p < 0.05).
• SUM149 and MDA‑MB‑231 platforms displayed increased vessel permeability and reduced endothelial coverage relative to the control (p < 0.05), indicating tumor‑driven barrier disruption.
• IBC platforms exhibited greater collagen porosity, suggesting active ECM remodeling that could facilitate tumor cell invasion.
• Notably, the MDA‑IBC3 platform showed progressive endothelial sprouting over three weeks. Confocal imaging revealed increasing sprout length, total network area, and sprout number (Kolmogorov‑Smirnov test, p < 0.001). Injection of 1 µm fluorescent microspheres confirmed lumen formation within sprouts on days 14 and 21, and sprouts encircled clusters of MDA‑IBC3 cells, recapitulating the in‑vivo “vascular nesting” phenotype of IBC.

The platform’s strengths lie in its ability to (a) maintain a continuous, shear‑conditioned endothelium, (b) provide a tunable ECM stiffness comparable to breast tumors, (c) allow real‑time, high‑resolution imaging of tumor‑vascular interactions, and (d) support high‑throughput experimental designs. Compared with prior 3‑D vascularized breast cancer models that lack IBC cells or continuous lumens, this system uniquely captures IBC‑specific angiogenic behavior and ECM dynamics.

Implications: This vascularized IBC model offers a versatile pre‑clinical testbed for dissecting mechanistic pathways (e.g., VEGF‑driven angiogenesis, ECM‑mediated invasion), screening anti‑angiogenic or anti‑invasive therapeutics, and potentially integrating immune or stromal components for more comprehensive studies. By bridging the gap between simplistic in‑vitro assays and costly animal models, it paves the way for more predictive, mechanistically informed drug development targeting the aggressive IBC phenotype.