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Controlled local presentation of matrix proteins in microparticle-laden cell aggregates
Abigail B Bernard1, Rebeccah Z Chapman, Kristi S Anseth
1Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, Colorado, 80303.
Insights
This study developed a novel cell-culture platform using hydrogel microwells to precisely control extracellular matrix (ECM) protein presentation within multicellular aggregates, enhancing research into cell-matrix interactions.
Area of Science:
- Biomaterials Science
- Cell Biology
- Tissue Engineering
Background:
- Multicellular aggregates, like Islets of Langerhans, interact with extracellular matrix (ECM) proteins.
- Existing cell-culture methods often limit ECM interaction to the exterior cells of aggregates.
- Platforms enabling study of internal ECM-cell interactions in 3D aggregates are needed.
Purpose of the Study:
- To develop a method for controlled, localized presentation of ECM proteins within multicellular aggregates.
- To investigate the spatial distribution and incorporation of ECM proteins using microparticles.
- To assess the scalability of the method for different aggregate sizes.
Main Methods:
- Utilized hydrogel microwell arrays to incorporate protein-laden microparticles during MIN6 β-cell aggregate formation.
- Varied microparticle seeding density to control protein incorporation.
- Co-presented multiple ECM proteins (laminin, fibronectin) using distinct microparticle populations.
- Scaled microwell dimensions to form aggregates of different sizes (∼80 and 160 µm).
Main Results:
- Reproducibly controlled the number of incorporated microparticles (total protein amount) by adjusting seeding density.
- Achieved relatively uniform spatial distribution of ECM-coated microparticles throughout the 3D aggregates.
- Demonstrated preservation of uniform local protein concentrations across different aggregate sizes.
- Showed that microparticle fraction within aggregates depended on seeding density, not aggregate size.
Conclusions:
- Developed a scalable cell-culture platform for precise control over ECM protein presentation within 3D multicellular aggregates.
- This method allows for uniform ECM-cell interaction studies throughout aggregates, overcoming limitations of previous techniques.
- The platform facilitates research into the role of ECM in cell function and survival within complex cellular structures.
Abstract:
Multi-cellular aggregates are found in healthy and diseased tissues, and while cell-cell contact is important for regulating many cell functions, cells also interact, to varying degrees, with extra-cellular matrix (ECM) proteins. Islets of Langerhans are one such example of cell aggregates in contact with ECM, both at the periphery of the cluster and dispersed throughout. While several studies have investigated the effect of reintroducing contact with ECM proteins on islet cell survival and function, the majority of these experiments only allow contact with the exterior cells. Thus, cell-culture platforms that enable the study of ECM-cell interactions throughout multi-cellular aggregates are of interest. Here, local presentation of ECM proteins was achieved using hydrogel microwell arrays to incorporate protein-laden microparticles during formation of MIN6 β-cell aggregates. Varying the microparticle seeding density reproducibly controlled the number of microparticles incorporated within three-dimensional aggregates (i.e., total amount of protein). Further, a relatively uniform spatial distribution of laminin- and fibronectin-coated microparticles was achieved throughout the x-, y-, and z-directions. Multiple ECM proteins were presented to β-cells in concert by incorporating two distinct populations of microparticles throughout the aggregates. Finally, scaling the microwell device dimensions allowed for the formation of two different sized cell-particle aggregates, ∼80 and 160 µm in diameter. While the total number of microparticles incorporated per aggregate varied with size, the fraction of the aggregate occupied by microparticles was affected only by the microparticle seeding density, indicating that uniform local concentrations of proteins can be preserved while changing the overall aggregate dimensions.
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