Tissue engineering the retinal ganglion cell nerve fiber layer

Abstract

Retinal degenerative diseases, such as glaucoma and macular degeneration, affect millions of people worldwide and ultimately lead to retinal cell death and blindness. Cell transplantation therapies for photoreceptors demonstrate integration and restoration of function, but transplantation into the ganglion cell layer is more complex, requiring guidance of axons from transplanted cells to the optic nerve head in order to reach targets in the brain. Here we create a biodegradable electrospun (ES) scaffold designed to direct the growth of retinal ganglion cell (RGC) axons radially, mimicking axon orientation in the retina. Using this scaffold we observed an increase in RGC survival and no significant change in their electrophysiological properties. When analyzed for alignment, 81% of RGCs were observed to project axons radially along the scaffold fibers, with no difference in alignment compared to the nerve fiber layer of retinal explants. When transplanted onto retinal explants, RGCs on ES scaffolds followed the radial pattern of the host retinal nerve fibers, whereas RGCs transplanted directly grew axons in a random pattern. Thus, the use of this scaffold as a cell delivery device represents a significant step towards the use of cell transplant therapies for the treatment of glaucoma and other retinal degenerative diseases.

Polycaprolactone Microfibrous Scaffolds to Navigate Neural Stem Cells

“…21 In addition to PCL, other biocompatible polymers have been used in nerve tissue engineering such as gelatin and polylactic acid (PLA). 16,17 However, accurately aligning the fibers in electrospinning method is difficult. 16,22,31 This method is not functional for cell encapsulating purposes due to the fact that the size of the fibers are mostly limited to nanoscales.…”

Retinal ganglion cell polarization using immobilized guidance cues on a tissue-engineered scaffold

“…[19] Briefly, Poly-D L-lactic acid (PLA, Purac Biomaterials Inc., PDL20) was dissolved in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP, Chem-Impex International Inc.) at a concentration of 6.6 % (wt/vol). The PLA solution was pumped by syringe pump (New Era Pump Systems Inc., NE-500) at a continuous feed rate of 2 ml/hr and ionized in a 20 gauge blunt-tipped needle (Hamilton) using a high voltage power supply (SpellmanHV, 230-30R).…”

Towards the development of a human glaucoma disease-in-a-dish model using stem cells

“…Already, bioengineered implants are being used to address this issue in animal models [85]. This group used a biodegradable electro-spun scaffold that promotes axonal radial growth towards the center of the retina.…”

“…For example, there are many obstacles in successfully co-culturing RGCs with superior colliculi explants in a 2D system, while attempting to study axonal growth guided by 3D signaling gradients and mechanical boundaries. Although techniques have been designed to bridge the gap between the artificial arrangement of co-cultured tissues and their in vivo counterparts, such as NASA's HRB, electrospun biodegradable scaffolding and ex vivo perfused human outflow pathway models, the field is lacking reliable substrates/ techniques for accurate modeling of the proposed co-culture systems [46,[58][59][60][61]85,86,88]. Even the complex 3D retina or optic nerve models that we described and proposed for future experiments are not physiologically representative of an in vivo system due to various reasons.…”