Abstract
Purpose :
We have recently prepared a biomaterial (patent pending) that comprises extracellular matrix proteins and proteoglycans (EMC). A cornea-like construct fabricated using EMC promoted the regeneration of corneal epithelium and fibroblasts (ARVO abstracts 2018, #2253). Biological or synthetic materials needed to make devices such as cornea-substitutes must possess characteristics of native tissue. The current study elucidated the physicochemical, optical and biological characteristics of the EMC and a cornea-like construct prepared with the biomaterial.
Methods :
EMC prepared in 15 mM HEPES buffer (pH 7.5) or in DMEM/F12 was used in all studies. Glutaraldehyde-based chemical crosslinking of EMC was employed to prepare a cornea-like construct. Optical (refractive index and transparency) and rheological properties (viscosity and viscoelasticity) were determined by employing standard protocols and appropriate equipment. Collagen fibrillar organization in the biomaterial and construct was analyzed by scanning electron microscopy (SEM). Epithelial and fibroblasts primary cultures were prepared using human or porcine corneas.
Results :
The light transmittance of EMC measured over wavelength range 400-750 nm was 80-90%, whereas the transmittance of the construct was 75-80%. The mean refractive index of EMC and construct is 1.335. Rheological data indicated viscous and elastic nature of the biomaterial. A linear decrease in EMC viscosity (2.0 to 0.0 Pa.s) was observed with an increase in applied shear rate (0.2-1.0 per sec). Viscoelasticity of EMC as determined from storage G’ and loss G’’ moduli as a function of angular frequency (rad/s) revealed the capability of EMC to transition from a liquid to solid state. The collagen fibril organization in EMC resembled that of stroma of human cornea. SEM images of both human cornea and EMC showed honeycomb architecture with interspersing spaces between the fibrils. Chemical processing to transform EMC into a construct did not alter the fiber arrangement. EMC activated intracellular signaling cascades and promoted the expression of corneal epithelial cell cycle progressing proteins.
Conclusions :
EMC possesses optical, physicochemical and biological features that are characteristic of cornea tissue. This biomaterial is highly suitable for the fabrication of a clinically viable therapeutic tool for the repair or replacement human corneas damaged due to trauma or dystrophy.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.