RESUMEN
To understand the response of oral epithelial cells, transplanted on corneal surface to the ocular cues in vivo. The corneal bu on obtained after penetrating keratoplasty (PK) of an eye of a patient with total limbal stem cell defi ciency (LSCD), previously treated with cultured oral mucosal epithelial transplantation (COMET) was examined by immunohistochemistry for the expression of keratins, p63, p75, PAX6, Ki-67, CD31, and CD34. COMET followed by optical-PK has improved visual acuity to 20/40 and rendered a stable ocular surface. The excised corneal tissue showed the presence of stratifi ed epithelium with vasculatures. The epithelial cells of the corneal bu on expressed K3, K19, Ki- 67, p63, p75 and the cornea-specifi c PAX6 and K12. This study confi rms that the oral cells, transplanted to corneal surface, survive and stably reconstruct the ocular surface. They maintain their stemness at the ectopic site and acquire some of the corneal epithelial-like characters.
RESUMEN
It has only been a quarter of a century since the discovery of adult stem cells at the human corneo-scleral limbus. These limbal stem cells are responsible for generating a constant and unending supply of corneal epithelial cells throughout life, thus maintaining a stable and uniformly refractive corneal surface. Establishing this hitherto unknown association between ocular surface disease and limbal dysfunction helped usher in therapeutic approaches that successfully addressed blinding conditions such as ocular burns, which were previously considered incurable. Subsequent advances in ocular surface biology through basic science research have translated into innovations that have made the surgical technique of limbal stem cell transplantation simpler and more predictable. This review recapitulates the basic biology of the limbus and the rationale and principles of limbal stem cell transplantation in ocular surface disease. An evidence-based algorithm is presented, which is tailored to clinical considerations such as laterality of affl iction, severity of limbal damage and concurrent need for other procedures. Additionally, novel fi ndings in the form of factors infl uencing the survival and function of limbal stem cells aft er transplantation and the possibility of substituting limbal cells with epithelial stem cells of other lineages is also discussed. Finally this review focuses on the future directions in which both basic science and clinical research in this fi eld is headed.
RESUMEN
Millions of people world over suffer visual disability due to retinal dystrophies which can be age-related or a genetic disorder resulting in gradual degeneration of the retinal pigmented epithelial (RPE) cells and photoreceptors. Therefore, cell replacement therapy offers a great promise in treating such diseases. Since the adult retina does not harbour any stem cells, alternative stem cell sources like the embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) offer a great promise for generating different cell types of the retina. Here, we report the derivation of four iPSC lines from mouse embryonic fibroblasts (MEFs) using a cocktail of recombinant retroviruses carrying the genes for Oct4, Sox2, Klf4 and cMyc. The iPS clone MEF-4F3 was further characterized for stemness marker expression and stable reprogramming by immunocytochemistry, FACS and RT-PCR analysis. Methylation analysis of the nanog promoter confirmed the reprogrammed epigenetic state. Pluripotency was confirmed by embryoid body (EB) formation and lineage-specific marker expression. Also, upon retinal differentiation, patches of pigmented cells with typical cobble-stone phenotype similar to RPE cells are generated within 6 weeks and they expressed ZO-1 (tight junction protein), RPE65 and bestrophin (mature RPE markers) and showed phagocytic activity by the uptake of fluorescent latex beads.