Bioengineering the Corneal Endothelium

February 1, 2012 -
11:45am to 1:00pm

The Fox Center for Vision Restoration organizes an exciting lecture series focusing on ocular regeneration and new therapies.

Distinguished national and international speakers present their innovative and multidisciplinary approaches to finding cures for vision impairment. The objective of this lecture series is to accelerate research through knowledge sharing, partnership building and out of the box thinking.

This lecture series should be of interest to: clinicians with an interest in ophthalmology; scientists and engineers interested in tissue engineering, cellular therapies and assistive technologies; students, postdoctoral fellows, residents and research staff.Adam Feinberg

Dr. Feinberg is the principal investigator of the Regenerative Biomaterials and Therapeutics Group, founded at Carnegie Mellon University in 2010. He earned his BS in Materials Science and Engineering from Cornell University in 1999 with co-op experience at Abiomed, Inc., working on total artificial hearts. This was followed by MS and PhD degrees in Biomedical Engineering from the University of Florida, where his doctoral work focused on engineering cell-material interactions to prevent and enhance adhesion.

Dr. Feinberg then moved to Harvard University as a Postdoctoral Fellow working on developing new biomaterials and cardiac tissue engineering strategies for 3-dimensional myocardial regeneration, with a focus on stem cell-based approaches (and two publications in Science). He subsequently joined CMU in the fall of 2010 as an Assistant Professor with joint appointments in Biomedical Engineering and Materials Science and Engineering.  His research group focuses on bottom-up engineering of the extracellular matrix, investigating the basic properties of engineered ECM as well as applying the engineered ECM to build new tissues. Dr. Feinberg has co-authored over 15 peer-reviewed publications and holds 9 US patents and patent applications.
 
Dr. Palchesko attended Indiana University of Pennsylvania for her undergraduate degree majoring in Biochemistry. She then attended Duquesne University working with Dr. Ellen Gawalt where she received her doctorate in Feb 2011 in surface chemistry focusing on covalently modifying the surface of bRachelle Palchesko one scaffold materials with bioactive molecules. She began in March 2011 as a Fox Center for Vision Restoration OTERO fellow working with Dr. Adam Feinberg at Carnegie Mellon University and Dr. James Funderburgh at the University of Pittsburgh.

Presentation Abstract

The corneal endothelium is responsible for maintaining the clarity of the cornea and loss of corneal endothelial cells (CECs) leads to impaired vision and the need for corneal transplantation. Descemet’s Membrane Endothelial Keratoplasty (DMEK) and related techniques are successful at restoring the pumping function of the endothelium, however donor corneas are limited worldwide and CEC loss can recur due to damage incurred during transplantation. A bioengineered corneal endothelium could be implanted using existing DMEK surgical techniques, but faces two primary challenges; (i) CECs are non-proliferative in vivo with minimal proliferation in vitro,making expansion of these cells for therapeutic application difficult and (ii) cell-sheet engineering techniques are unable to recreate a basement membrane similar to Descemet’s membrane (DM) for attachment to the anterior side of the stroma. 

Here we report initial work toward solving these two major challenges and making a bioengineered corneal endothelium a therapeutic reality. First, in vitro expansion of CECs is limited to a few passages and the CECs rapidly de-differentiate into fibroblast-like cells that lose CEC phenotypic markers. This makes it difficult to expand enough CECs in vitro for therapeutic applications such as bioengineering a corneal endothelium. We hypothesized that mimicking the extracellular matrix (ECM) and mechanical properties of the DM would promote maintenance of phenotype while enabling cell expansion. Compared to standard tissue culture polystyrene, we have engineered a biomimetic substrate with a unique ECM protein coating and low stiffness that enables bovine CECs to be passaged up to 8-times while maintaining a hexagonal morphology and expression of zona occludens 1 (ZO-1). Preliminary estimates indicate a ~3000-fold expansion of CECs, suggesting that a similar strategy may be successful for expanding human CECs. Second, DMEK is a clinically successful procedure, suggesting that a bioengineered cornea with similar handling characteristics and pumping function would be a viable option for corneal repair. We hypothesized that engineering a basement membrane with chemical and mechanical properties similar to the DM would be an ideal scaffold. We have used surface-initiated assembly to engineer ECM protein nanofabrics that match the laminin and collagen type IV composition of the DM and are working towards engineering a functional endothelium using these materials.  

In summary, we have developed a number of biomimetic technologies for tissue engineering a corneal endothelium. The in vitro expansion of bovine CECs was significantly enhanced by engineering cell culture substrates that match the chemical and mechanical properties of the DM. Using a similar strategy, we have engineered ECM scaffolds from laminin and collagen type IV and are actively developing methods to use these to form bioengineered endothelium. Future work includes transitioning from bovine to human CECs, establishing in vitro assays to validate pump function of the bioengineered endothelium and in vivo evaluation in an animal DMEK model.

Location and Address

Eye and Ear Boardroom, 5th floor, Eye and Ear Institute
203 Lothrop Street, Pittsburgh PA 15213