Modeling of Lowe Patient-Derived Induced Pluripotent Stem Cells Into Trabecular Meshwork.

PURPOSE: Congenital glaucoma is the leading cause of vision loss in patients with Lowe syndrome (LS), a rare X-linked disease caused by mutations in the OCRL gene. OCRL encodes an inositol polyphosphate 5-phosphatase. Despite significant research efforts, the pathogenesis of glaucoma caused by OCRL deficiency remains unclear, partly due to the inaccessibility of patient-derived ocular cells.

DESIGN

The study design is a comparative cell-based study focused on the functional characterization of induced human trabecular meshwork (iHTM) cell lines.

METHODS

Two induced LS pluripotent stem cell (iPSC) lines, previously isolated and generated from an LS patient family, were differentiated into trabecular meshwork cells. LS100 is an affected LS patient; LS200 is an unaffected healthy sibling. Patient-based trabecular meshwork (iHTM) cell models were generated. Both stem cell and trabecular meshwork markers were evaluated by both immunoblot as well as immunostaining analysis.

RESULTS

Induced trabecular meshwork cells expressed TM cell markers such as collagen IV, accompanied by the loss of pluripotency markers like OCT4. TM-like responses upon dexamethasone challenge included increased cross-linked actin network formation. The phagocytic function of TM cells was demonstrated by fluorescent labeling phagocytosis assay. Immunostaining revealed that compared to LS200-iHTM, LS100-iHTM had shortened primary cilia. This defect was further supported by reduced Gli1 protein expression in LS100-iHTM. Immunostaining of LAMP1, a lysosome marker, showed greater perinuclear lysosome clustering in LS100-iHTM than LS200-iHTM, indicating potentially dysfunctional nutrient sensing in the patient-derived iHTM cells.

CONCLUSIONS

We established two iHTM cell lines derived from iPSCs of an LS patient and his healthy sibling. Functional characterization of both cell lines showed that OCRL deficiency in LS altered downstream pathways related to phagocytosis, primary ciliogenesis, and lysosome positioning. iHTM cells function like TM cells and retain LS-associated defects, highlighting their potential as in vitro models for future mechanistic and therapeutic studies.