Protein Engineering of Multi-functional Biomaterials for Regenerative Medicine
Stem cell transplantation is a promising therapy for a myriad of debilitating diseases and injuries; however, current delivery protocols are inadequate. Transplantation by direct injection, which is clinically preferred for its minimal invasiveness, commonly results in less than 5% cell viability, greatly inhibiting clinical outcomes. We demonstrate that mechanical membrane damage results in significant acute loss of viability at clinically relevant injection rates. As a strategy to protect cells from these detrimental forces, we show that cell encapsulation within hydrogels can significantly improve transplanted cell viability. Building on these fundamental studies, we have designed a family of injectable, bioresorbable, customizable hydrogels using protein-engineering technology. By integrating protein science methodologies with simple polymer physics models, we manipulate the polypeptide chain interactions and demonstrate the direct ability to tune the material properties including hydrogel mechanics, cell-adhesion, and biodegradation. Through a series of in vitro and in vivo studies, we demonstrate that protein-engineered hydrogels may significantly improve transplanted stem cell retention and regenerative function. Furthermore, many of the lessons learned about designing injectable biomaterials can be extended to design new bio-inks for 3D printing applications. While 3D printing has enormous potential for tissue engineering, few bio-inks are currently available to facilitate the printing of complex, cell-laden constructs. We demonstrate the design of a new, customizable bio-ink that enables the printing of multiple cell types into distinct geometric forms.
Materials Science and Engineering Stanford University
Sarah Heilshorn’s interests include biomaterials in regenerative medicine, engineered proteins with novel assembly properties, microfluidics and photolithography of proteins, and synthesis of materials to influence stem cell differentiation. Current projects include tissue engineering for spinal cord and blood vessel regeneration, designing injectable materials for use in stem cell therapies, and the design of microfluidic devices to study the directed migration of cells (i.e., chemotaxis). She graduated from Georgia Tech with a BS in Chemical Engineering in 1998, and completed her Ph.D. at Caltech in 2004. Dr. Heilshorn’s awards and honors include the National Institutes of Health New Innovator Award, the National Science Foundation’s CAREER Award, the American Chemical Society’s New Investigator Award. She is a Fellow of the American Institute for Medical and Biological Engineering (AIMBE) and a William R. and Gretchen B. Kimball University Fellow in Undergraduate Education at Stanford.
Molecular Engineering and Sciences Seminar Series
This weekly seminar brings together students, faculty and invited guests from various disciplines across campus to explore current trends in molecular engineering and nanotechnology. It is a forum for active interdisciplinary discussions. These talks are open to the public and attract a diverse audience of students and faculty.