(616c) Biomimicry of Cellular Ligand Presentation in 3D Stem Cell Scaffolds Via Proteolipobead-Matrix Hybrid Systems

Biomimicry of Cellular Ligand Presentation in 3D Stem Cell Scaffolds Via Proteolipobead-Matrix Hybrid Systems 

Eric Fried¹, Bin He¹, Michelle Gupta², Devika Varma², Steve Nicoll, PhD² and M. Lane Gilchrist, PhD¹

¹Department of Chemical Engineering, The City College of New York (of CUNY)

²Department of Biomedical Engineering, The City College of New York (of CUNY)

Re-creation of the complex 3-D microenvironment of the stem cell niche in order to elicit regenerative control is one of the major challenges in biomaterials research. We hypothesize that the introduction of biomembrane-microsphere assemblies into 3D scaffolds is a viable biomimetic means to present ligands/bound factors to stem cells and mimic cellular communication in the stem cell niche. We have developed a new platform to present molecules to stem cells in 3D within a biomimetic architecture: as laterally-mobile molecules embedded in a tailored biomembrane. The presentation of ligands/bound factors involved in cell-cell interactions (e.g. cadherin) has begun in 2D culture systems by surface patterning but has not yet been well established in 3D stem cell culture systems. 

We present results on three aspects of this study: 1) the fabrication and characterization of functionalized microspheres that contain supported lipid bilayers; 2) the construction and characterization of hydrogel/microsphere hybrid scaffolds that integrate tether-supported lipid bilayers on microspheres of various sizes and 3) preliminary studies of human mesenchymal stem cells (hMSCs) microencapsulated into matrix/microsphere hybrid scaffolds. Special attention was given to the hMSC cytoskeletal response, including 3D localization of tubulin, actin, and catenin. Biosynthesis of extracellular matrix proteins by hMSCs was also monitored. 

Confocal microscopy studies were conducted to visualize proteolipobead-displayed N-cadherin engaged in interactions with hMSCs in situ, from 3D CLSM reconstruction of hMSCs in N-cadherin proteolipobead/matrix 3D constructs. Immunohistochemical staining was used to localize the N-Cadherin within the hybrid matrices relative to counterstained supported lipid bilayers. Ongoing experimentation utilizes confocal spectral 3-D imaging and state-of-the-art structured illumination microscopy (SIM) for superesolution imaging. This work constitutes a new method for displaying a wide range of complex membrane proteins and signaling molecules to live cells within 3D matrices. We present further investigations of MSC-PLB interactions under a range of conditions and surface/material characteristics of the PLB substrates.