Interaction of Particles on Material Surfaces
Central to the development of biomaterials for use in a biomedical application is their ability to interact with the surrounding tissue in a favorable manner either by repelling the cells as in antimicrobial and antiviral surfaces, or by promoting cellular growth and in regulating cell behavior as in regenerative medicine. These interactions are modulated by the proteins that are first adsorbed onto the material surface. In our laboratory, we have been studying these protein-substrate and cell-substrate interactions by several direct and indirect measurements. Quartz crystal microbalance that can measure adsorbed masses with nanogram sensitivity, is used to measure the adsorption, or its absence, by monitoring the changes in the mass, as well as the viscoelastic behavior of the substrate. We often employ Langmuir balance to measure the thermodynamics of the interactions between polymer surfaces and proteins. Surface-sensitive x-ray scattering measurements are also used to investigate interactions of particles onto materials surfaces. These physical measurements are validated by appropriate direct observation of cell response by growing and monitoring the cells on these surfaces.
Scaffold-guided Lineage Specific Differentiation of Stem Cells
Extracellular matrix (ECM) harbors biological cues to guide cellular behaviors. Polymeric scaffolds with tunable mechanical properties can be modified with cell type specific ECM. We are interested in exploring the role of cell type specific ECM on the differentiation of stem cells. ECM-polymeric hybrid scaffolds are prepared by culturing and decellularizing different type of primary cells on 3D polymer scaffolds. We showed that cell-type specific ECM-polymer scaffolds can guide the linage-specific differentiation of human stem cells.
The chemistry and structure of polymeric scaffold influence the cellular functions. We are also interested in investigating the effect of polymer design on the differentiation of stem cells.
Expansion of Chondrocytes with Reduced Dedifferentiation
In vitro expansion of chondrocytes is a key step for cell-based cartilage repair therapy. However, the in vitro expansion of chondrocytes inevitably leads to the dedifferentiation of cells and results in the poor quality of chondrocytes after expansion. We are interested in studying ways to mitigate the dedifferentiation of chondrocytes. We have identified a lower adhesive substrate and chondrocyte-derived ECM can reduce the dedifferentiation during in vitro expansion.
Antimicrobial activity of biomaterials
We are interested in the antimicrobial properties of biological materials and synthetic polymeric materials. We demonstrated the mechanism of action of the anti-bacterial activity of human amniotic membrane. We use standard or customized anti-bacterial including anti-biofilm assays to evaluate the infection resistant properties of polymeric surfaces.
Cells interact with mechanical signals from their environment. These physical cues play an important role in directing cell function and fate, yet the mechanisms by which mechanical signals lead to changes in gene expression are not fully understood. We are interested in using biomaterials to make engineered microenvironments to study how mechanical signals influence different cellular processes.