(805c) Novel 3D Microenvironments for Mesenchymal Stem Cell Engagement By Hydrogel-Embedded Proteolipobeads

Fried, E., City College of New York of CUNY
Gilchrist, L., City College of New York of CUNY
Nicoll, S., City College of New York
Gupta, M., City College of New York of CUNY
Varma, D., City College of New York of CUNY

A major challenge in biomaterials research is the re-creation of complex 3D stem cell microenvironments as a route to regenerative control. 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. Our ligand display platform, termed proteolipobeads (PLBs), features laterally-mobile proteins and peptides 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 viability of hMSCs within this platform, as well as the frequency and extent of hMSC-PLB interactions.

 Confocal microscopy studies were conducted to visualize N-cadherin-mediated PLB interactions with hMSCs in situ. Immunohistochemical staining was used to localize the N-Cadherin within the hybrid matrices relative to counterstained supported lipid bilayers. Ongoing experimentation utilizes state-of-the-art structured illumination microscopy (SIM) for superesolution fluorescence imaging of live cells. This work constitutes a new method for displaying a wide range of complex membrane proteins and signaling molecules to live cells within 3D matrices.