Transcriptome analysis for the identification of cellular markers related to trabecular meshwork differentiation.

BACKGROUND: Development of primary open-angle glaucoma (POAG) is associated with the malfunctioning trabecular meshwork (TM). Cell therapy offers great potential for the treatment of POAG, but requires the generation of functional TM cells in vitro to replace the lost/dysfunctional cells. TM differentiation in vitro from various stem cell types must be monitored by the expression of specific markers. However, no single definitive marker of the TM has been identified. RESULTS: To identify robust markers of TM differentiation, we performed global transcriptome profiling using high-density oligonucleotide microarray on ex vivo TM tissue and cultured TM progenitors. Corneal and scleral tissues were also used in the analysis. After removal of genes expressed in the cornea and sclera, 18 genes were identified that were differentially expressed in the TM relative to the other samples. CDH23, F5, KCNAB1, FGF9, SPP1, and HEY1 were selected among the genes highly expressed in the TM, together with BDNF which was repressed, compared to progenitors for further investigation. Expression analysis by qPCR verified the differential expression and immunofluorescence of the anterior segment confirmed strong expression in the TM. CONCLUSIONS: Three independent cohort of expression studies have identified novel markers, fitting in identifying TM cells and in evaluating directed TM differentiation in vitro.

Identification and characterization of mesenchymal stem cells derived from the trabecular meshwork of the human eye.

Mesenchymal stem cells (MSC) have been isolated from several adult human tissues. Their propensity to differentiate into cell types of connective tissue, such as osteocytes, chondrocytes, and adipocytes, suggests that MSC may function as a reserve of progenitor cells that repair and maintain healthy adult tissues. Dysfunction of the trabecular meshwork (TM), a connective tissue at the anterior region of the human eye that regulates intraocular pressure, plays a major role in the pathogenesis of glaucoma. The mechanobiology and pharmacological aspects of the TM tissue have been relatively well studied in disease states. Less well understood is if there are progenitor cells within the TM that contribute to maintenance of this tissue. In this study, we have identified and characterized an expandable population of cells that have stem cell-like properties. In particular, these cells express the markers CD73, CD90, and CD105, which are typically associated with MSC. Thus, we have named these cells TM-MSC. As further evidence that these cells are MSC, they were differentiated in vitro into adipocytes, osteocytes, and chondrocytes. Through genomic characterization, we show that TM-MSC have gene expression patterns most similar to MSC derived from other tissues. TM-MSC express genes found on adult TM tissue, suggesting that TM-MSC are progenitor cells that serve to maintain a healthy TM.