Progenitors for the Corneal Endothelium and Trabecular Meshwork: A Potential Source for Personalized Stem Cell Therapy in Corneal Endothelial Diseases and Glaucoma

Abstract

Several adult stem cell types have been found in different parts of the eye, including the corneal epithelium, conjunctiva, and retina. In addition to these, there have been accumulating evidence that some stem-like cells reside in the transition area between the peripheral corneal endothelium (CE) and the anterior nonfiltering portion of the trabecular meshwork (TM), which is known as the Schwalbe's Ring region. These stem/progenitor cells may supply new cells for the CE and TM. In fact, the CE and TM share certain similarities in terms of their embryonic origin and proliferative capacity in vivo. In this paper, we discuss the putative stem cell source which has the potential for replacement of lost and nonfunctional cells in CE diseases and glaucoma. The future development of personalized stem cell therapies for the CE and TM may reduce the requirement of corneal grafts and surgical treatments in glaucoma.

Bovine Posterior Limbus: An Evaluation of an Alternative Source for Corneal Endothelial and Trabecular Meshwork Stem/Progenitor Cells

“…However, meridional examination shows that the most anterior portion of the bovine TM also taper to insert beneath the peripheral cornea. This observation is novel as far as we know, leading to the speculation that stem-like cells may also be present in the bovine transition area, since the transition in primates is considered stem cell-rich [6].…”

“…Nonetheless, these may not lower the IOP adequately in some patients. Therefore, the potential to repair or replace the diseased CE or TM through a cell repopulation approach is an important area that needs to be explored [6]. It is believed that the IOP-lowering effect of glaucoma laser treatment has given a proof of principle for the credibility of a tissue rejuvenation approach [7].…”

“…In fact, the putative stem cells in the peripheral CE, transition zone, and TM have not been clearly defined. Thus, we have collectively named them PET cells (progenitor cells of the endothelium and trabeculum) [6].…”

“…Our data suggest that the spheres had a bipotent potential and were more prone to adopt their original lineage, indicating that they may be more appropriate for regeneration purposes than pluripotent or multipotent stem cells. The evidence suggesting the presence of stem cells in the human TM has been accumulating for some time [6,7,9,12,15]. To date, there have been five studies that successfully cultivated the TM stem cells in vitro [16][17][18]72,73].…”

Biomaterials for Regenerative Medicine Approaches for the Anterior Segment of the Eye

“…[4] There is a fourth nonfiltering region, termed the insert region, where the trabecular meshwork inserts under the periphery of the corneal endothelium and is the location of the progenitor cell niche. [5] The uveal meshwork is located closest to the anterior chamber, composed of large connective tissue beams of lamellae which form large irregular intratrabecular spaces. The CS region is composed of flatter lamellae with progressively smaller intratrabecular spaces toward the JCT.…”