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For drug discovery, new in vitro cancer models are needed to obtain more translatable study outcomes in a low-cost and high-throughput manner. For this purpose, 3D cancer spheroids have been established as more effective than 2D models. Current commercial techniques, however, rely heavily on self-aggregation of dissociated cells and cannot replicate key features of the native tumor microenvironment, particularly due to a lack of control over extracellular matrix components and heterogeneity in size and aggregate-forming tendencies. Also, current spheroidal techniques are typically limited to one spheroid per well, therefore providing a narrow range of cell numbers per well, disadvantageous for assay development in drug screening. Here, we overcome these challenges by coupling tissue engineering toolsets with microfluidic technologies to create engineered cancer microspheres and sorting desired numbers of microspheres into assay-ready well-plate format. To form the engineered cancer microspheres, MCF7 (non-metastatic) and MDA-MB-231 (metastatic) breast cancer cells were encapsulated within poly(ethylene glycol)-fibrinogen hydrogels using our previously developed microfluidic platform. Highly uniform cancer microspheres (intra and inter-batch coefficient of variation ≤ 5%) with high cell densities (over 20 × 106 cells/ml) were produced rapidly, which is critical for use in drug testing. The microspheres supported the 3D culture of both breast cancer cell lines over at least 14 days in culture. Encapsulated cells displayed cell type-specific differences in morphology, proliferation, metabolic activity, ultrastructure, and overall microsphere size distribution and bulk stiffness. To prepare assay-ready pre-plated microspheres, a COPAS FP flow cytometer was used for its ability to analyze and sort large sample particles such as tumor spheroids and hydrogel cancer microspheres generated in this study. When using a 96-well plate, the sorting rate varied from 2.5 - 6 microspheres per second, depending on the sample concentration. When sorting a desired number of microspheres per well, the accuracy was greater than 95% as verified visually by microscopy. Viability of sorted microspheres was verified 24 hours post-sort. Shipping conditions were established that maintained cell viability for remote use in drug testing. Methods for compound addition by pinning and imaging were tested and optimized. Using these approaches, the microsphere system was shown to be compatible with an automated liquid handling system for administration of drug compounds; MDA-MB-231 microspheres were distributed in 384 well plates and treated with chemotherapeutic drugs. Expected responses were quantitated using CellTiter-Glo® 3D and detected using automated imaging. Overall, our results demonstrate initial applicability for the tissue-engineered cancer microspheres for drug screening.
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Microsphere‐Enabled Modular Formation of Miniaturized In Vitro Breast Cancer Models
Abstract In search of effective therapeutics for breast cancers, establishing physiologically relevant in vitro models is of great benefit to facilitate the clinical translation. Despite extensive progresses, it remains to develop the tumor models maximally recapturing the key pathophysiological attributes of their native counterparts. Therefore, the current study aimed to develop a microsphere‐enabled modular approach toward the formation of in vitro breast tumor models with the capability of incorporating various selected cells while retaining spatial organization. Poly (lactic‐co‐glycolic acid) microspheres (150‐200 mm) with tailorable pore size and surface topography are fabricated and used as carriers to respectively lade with breast tumor‐associated cells. Culture of cell‐laden microspheres assembled within a customized microfluidic chamber allowed to form 3D tumor models with spatially controlled cell distribution. The introduction of endothelial cell‐laden microspheres into cancer‐cell laden microspheres at different ratios would induce angiogenesis within the culture to yield vascularized tumor. Evaluation of anticancer drugs such as doxorubicin and Cediranib on the tumor models do demonstrate corresponding physiological responses. Clearly, with the ability to modulate microsphere morphology, cell composition and spatial distribution, microsphere‐enabled 3D tumor tissue formation offers a high flexibility to satisfy the needs for pathophysiological study, anticancer drug screening or design of personalized treatment.
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- Award ID(s):
- 2219014
- PAR ID:
- 10526359
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Small
- Volume:
- 20
- Issue:
- 17
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/smll.202307365
