The goal of the project is to develop well-defined synthetic matrices composed of polymers and peptides to support stem cell growth and differentiation. Over the past year, we have used our array-based, high-throughput approach for the systematic investigation of the effects of polymers and peptides on human pluripotent stem cell (hPSCs) maintenance and differentiation. We have also extended our studies to neural progenitor cells (NPCs) derived from hPSCs because they offer a unique model system to study neural development and are a possible source of cells to treat a variety of neurodegenerative disorders. Current practices for deriving, expanding, and differentiating NPCs generally utilize empirically determined combinations of reagents, which are expensive, difficult to isolate, subject to batch-to-batch variations, and unsuitable for cell-based therapies. In contrast, synthetic polymers that are inexpensive and easy to fabricate represent a reliable alternative for in vitro NPC expansion.
We found that a combination of physical cues modulate protein adsorption to our previously developed hydrogels as well as the signaling properties of these proteins, which in turn directly affect human pluripotent stem cell (hPSCs) maintenance and differentiation. We identified of a number of candidate polymers that support short-term NPC attachment, growth, and maintenance of pluripotency. Furthermore, we are starting to test large polymer coated slides to investigate the scalability of the polymers’ physiochemical properties and biological performance. Our data shows that the optimum polymer composition was able to support the attachment and growth of NPCs and that they retained the ability to differentiate to cells with neuronal-like morphologies.
In addition, we also diversified our microarray technology to use a library of synthetic peptides that are designed to have similar functionalities to those of extracellular matrix proteins. These peptides retain the functional properties of proteins, are more stable and versatile, and are relatively inexpensive. Preliminary data demonstrate that hPSCs are able to adhere to these peptides in a dose dependent manner.
Previously established extracellular matrix protein (ECMP) and growth factor (GF) array technology are currently testing optimal ECMP-GF combinations for their ability to maintain and stabilize a definitive endoderm population over multiple passages. These experiments are an extension of several recent publications from our group. Although these studies do not involve synthetic polymers or peptides, they provide important proof-of-principle that this screening platform can be applied to the differentiation and expansion of definitive endoderm.