Abstract
Purpose: :
Silk fibroin is a choice biomaterial for the design of cellular scaffolds for applications related to regenerative medicine. Recently, the use of fibroin films for ophthalmic applications has been under investigation due to their transparent nature and controllable material properties. Of particular interest is the recent finding that silk film surfaces can be patterned to produce a variety of surface topographies. The following study investigates the effects of various silk film geometrical topographies upon corneal epithelium cell adhesion, proliferation, and cell sheet migration.
Methods: :
Microfabrication techniques were utilized to manufacture various silicon surfaces. Each patterned surface consisted of 2 um width, 2 um pitch, and 1.5 um depth features. Features were designed to produce various geometrical shapes consisting of lines, concentric rings, and spiral patterns. PDMS negative molds were produced from the silicon pattern, which were then used to cast silk fibroin solution upon. A well characterized cell line, human corneal-limbal epithelium (HCLE), was used to assess initial cell adhesion, culture proliferation, and cell sheet migration effects upon the various topographies, which included both flat silk film surfaces and tissue culture plastic (TCP).
Results: :
Cell adhesion studies demonstrated that on average all silk film surfaces exhibited equal cell attachment after a 2 hr culture period; in addition, it was found that TCP had 60% greater cell adherence than silk film substrates. MTT cell proliferation assays indicated that cell number was at 30% TCP levels for silk films after day 1 in culture and increased to equal levels by day 5. Scratch wound cell migration assays indicated that cell sheet movement into the damaged region followed the geometrical pattern orientation, while overall migration rates varied for each substrate.
Conclusions: :
Silk films provide a less adhesive surface for initial cell attachment when compared to TCP, while allowing for culture expansion over time that is comparable to TCP. En masse migration is affected by the presented topography. These results indicate that patterned silk films may offer a new biomaterial option in the clinical setting for potential uses in ocular surface repair for expediting epithelial healing after injury.
Keywords: cornea: epithelium • proliferation • regeneration