Abstract
Purpose: :
Severe ocular surface chemical injury can lead to limbal stem cell deficiency (LSCD). Clinical features of LSCD include conjunctivalization of the ocular surface, corneal neovascularization, stromal scarring, and visual loss. Autologous omental cell transplantation has been used in animal models for the treatment of renal and spinal cord injuries with beneficial effects. Omental stromal cells (OSC) in culture express adult stem cell and pluripotent embryonic cell markers including: WT-1, CXCR4, CD133, OCT-4, and NANOG. These cells have successfully been shown to migrate to injured kidney and subcutaneous sites after systemic or local injection. The clinical role of these cells in ocular injury models has not been reported. This study examines the effect of subconjunctival delivery of isolated omental stromal cells on the healing process in an alkali induced stem cell deficiency model in rats.
Methods: :
OSCs were isolated from donor Fisher 344 rats using an established protocol involving initial intraperitoneal injection with 5 ml polydextran particle slurry and subsequent culture of the "activated" omental cells. Bilateral corneal alkali injury was created in another group of Fisher 344 rats using lens paper soaked in 2.5 N NaOH placed onto the cornea for 20 seconds. Cultured omental cells (5 X 105 cells = 0.1 ml) or an equal volume of culture medium without serum were injected subconjunctivally 1 day following injury (n=6). Anterior segment photographs were taken at days 0, 4, and 8. On post-injury days 4 and 8, all rats were graded for corneal opacification and corneal neovascularization using an established grading technique in a masked fashion.
Results: :
A Mann-Whitney test was used to determine the significance of differences in corneal opacification and neovascularization between the control and test groups at both 4 and 8 days after alkali burn injury. Within our sample, there was no significant difference in the grade of corneal opacification between the control eyes and the omental cell injection eyes. However, the grade of corneal neovascularization did differ significantly between the control and omental cell injection eyes at both 4 days (U = 7, p < 0.05 one-tailed), and at 8 days (U = 0, p < 0.01 one-tailed).
Conclusions: :
Our results suggest that omental stromal cells may have a beneficial role in corneal healing after alkali burn injury. In particular, the significant difference in corneal neovascularization suggests that omental stromal cells may provide some inhibitory effect on the neovascular growth and perhaps support limbal stem cell survival. Further studies are necessary to elucidate the exact mechanism of action of the omental stromal cells in this chemical injury model.
Keywords: cornea: basic science • cornea: clinical science • cornea: epithelium