Transplanting Retinal Cells Using Bucky Paper for Support

NASA Tech Briefs, Aug 2004

Bucky paper supports the cells before, during, and after surgery.

Ames Research Center, Moffett Field, California

A novel treatment for retinal degenerative disorders involving transplantation of cells into the eye is currently under development at NASA Ames Research Center and Stanford University School of Medicine. The technique uses bucky paper as a support material for retinal pigment epithelial (RPE) cells, iris pigment epithelial (IPE) cells, and/or stem cells. This technology is envisioned as a treatment for age-related macular degeneration, which is the leading cause of blindness in persons over age 65 in Western nations. Additionally, patients with other retinal degenerative disorders, such as retinitis pigmentosa, may be treated by this strategy.

Bucky paper is a mesh of carbon nanotubes (CNTs), as shown in Figure 1, that can be made from any of the commercial sources of CNTs. Bucky paper is biocompatible and capable of supporting the growth of biological cells. Because bucky paper is highly porous, nutrients, oxygen, carbon dioxide, and waste can readily diffuse through it. The thickness, density, and porosity of bucky paper can be tailored in manufacturing. For transplantation of cells into the retina, bucky paper serves simultaneously as a substrate for cell growth and as a barrier for new blood vessel formation, which can be a problem in the exudative type of macular degeneration.

Bucky paper is easily handled during surgical implantation into the eye. Through appropriate choice of manufacturing processes, bucky paper can be made relatively rigid yet able to conform to the retina when the bucky paper is implanted. Bucky paper offers a distinct advantage over other materials that have been investigated for retinal cell transplantation - lens capsule and Descemet's membrane - which are difficult to handle during surgery because they are flimsy and do not stay flat.

In preparation for implantation, the selected cells are first cultured onto a piece of bucky paper. A retinotomy is then performed, the cell-covered bucky paper is implanted, and the retina is reattached. Because bucky paper does not trigger an inflammatory reaction in the eye, it can be left in place after transplantation to serve as a basement membrane patch.

The attachment of RPE (see Figure 2), IPE, and/or stem cells onto the bucky paper may be enhanced by chemically modifying or coating the bucky paper with one or more biologically active substances. The ability to easily make these modifications may serve as an important way of optimizing retinal cell transplantation for macular degeneration and retinitis pigmentosa and may facilitate other ophthalmologic applications as well.

This patent pending work was performed by David J. Loftus, Martin Cinke, and Meyya Meyyappan of Ames Research Center, Center for Nanotechnology, and by Harvey Fishman, Ted Leng, Philip Huie, and Kalayaan Bilbao of Stanford University School of Medicine, Department of Ophthalmology. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the BioMedical category.

Inquiries concerning rights for the commercial use of this invention should be addressed to the Patent Counsel, Ames Research Center, (650) 604-5104. Refer to ARC-14940.