Kazuko Asada

Cell Homogeneity Indispensable for Regenerative Medicine by Cultured Human Corneal Endothelial Cells

PURPOSE To identify the subpopulation (SP) among heterogeneous cultured human corneal endothelial cells (cHCECs) devoid of cell-state transition applicable for cell-based therapy. METHODS Subpopulation presence in cHCECs was confirmed via surface CD-marker expression level by flow cytometry. CD markers effective for distinguishing distinct SPs were selected by analyzing those on established cHCECs with a small cell area and high cell density. Contrasting features among three typical cHCEC SPs was confirmed by PCR array for extracellular matrix (ECM). Combined analysis of CD markers was performed to identify the SP (effector cells) applicable for therapy. ZO-1 and Na+/K+ ATPase, CD200, and HLA expression were compared among heterogeneous SPs. RESULTS Flow cytometry analysis identified the effector cell expressing CD166+CD105-CD44-∼+/-CD26-CD24-, but CD200-, and the presence of other SPs with CD166+ CD105-CD44+++ (CD26 and CD24, either + or -) was confirmed. PCR array revealed three distinct ECM expression profiles. Some SPs expressed ZO-1 and Na+/K+ ATPase at comparable levels with effector cells, while only one SP expressed CD200, but not on effector cells. Human leukocyte antigen expression was most reduced in the effector SP. The proportion of effector cells (E-ratio) inversely paralleled donor age and decreased during prolonged culture passages. The presence of Rho-associated protein kinase (ROCK) inhibitor increased the E-ratio in cHCECs. The average area of effector cells was approximately 200∼220 μm2, and the density of cHCECs exceeded 2500 cells/mm2. CONCLUSIONS A specified cultured effector cell population sharing the surface phenotypes with mature HCECs in corneal tissues may serve as an alternative to donor corneas for the treatment of corneal endothelial dysfunction.

Metabolic Plasticity in Cell State Homeostasis and Differentiation of Cultured Human Corneal Endothelial Cells.

Purpose To clarify whether cultured human corneal endothelial cells (cHCECs), heterogeneous in their differentiation state, exhibit distinctive energy metabolism with the aim to develop a reliable method to sort cHCECs applicable for regenerative medicine. Methods The presence of cHCEC subpopulations (SPs) was verified via surface cluster-of-differentiation (CD) marker expression. Cultured HCEC metabolic extracts or corresponding culture supernatants with distinctive cellular phenotypes in regard to energy-metabolism-related functional markers c-Myc and CD44 were prepared and analyzed via capillary electrophoresis-tandem mass spectrometry. The metabolic requirements of heterogeneous SPs of cHCECs were also investigated. Results After successfully discriminating SPs, as verified via surface CD markers in terms of their secretory metabolites, we found that the CD44+++ SP with cell-state transition (CST) exhibited disposition for anaerobic glycolysis, whereas the CD44-SP without CST was disposed to mitochondria-dependent oxidative phosphorylation (OXPHOS). These results raised the possibility of establishing effective culture conditions to selectively expand mature cHCECs with a hexagonal cobblestone shape and inclination for mitochondria-dependent OXPHOS. Conclusions The findings of this study open a pathway for monitoring the disposition of cHCECs via their energy metabolism, thus leading to safe and stable regenerative medicine by use of metabolically defined cHCECs in cell-suspension form.

Concomitant Evaluation of a Panel of Exosome Proteins and MiRs for Qualification of Cultured Human Corneal Endothelial Cells

PURPOSE We elucidate a method to use secreted miRNA profiles to qualify cultured human corneal endothelial cells (cHCECs) adaptable for cell-injection therapy. METHODS The variations of cHCECs in their composites of heterogeneous subpopulations (SPs) were verified in relation to their surface cluster-of-differentiation (CD) markers. Integrated analysis of micro RNA (miRNA) profiles in culture supernatants (CS) were investigated by 3D-Gene Human microRNA Chips. To validate 3D-Gene results, quantitative real-time PCR was done from numerous cultures with distinct morphology and SP composition. Exosomes and miRNAs in CS also were analyzed. RESULTS Secreted miRNA profiles among morphologically-diverse cHCEC SPs proved useful for individual distinction. Candidate miRNAs to discriminate CD44- SPs from those with CD44++ ∼ CD44+++ phenotypes were miRs 221-3p, 1246, 1915-3p, and 4732-5p. The levels of the latter-three miRs decreased dramatically in cHCEC CS without cell-state transition (CST) compared to those of control medium, whereas those from cHCECs with senescence-like CST showed an increase. MicroR184 decreased inversely in parallel with the upregulation of CD44 on cHCECs. CD9+ exosomes were more elevated in cHCEC CS with senescence-like CST than those without CST, indicating the possible import of these extracellular vesicles (EVs) into cHCECs without CST. CONCLUSIONS Cultured HCECs sharing a CD44- phenotype of matured HCECs may be discriminated by measuring the amount of miRNAs or exosome in CS. Thus, miRNA in CS may serve as a tool to qualify cHCECs. Future detailed analysis of cell-to-cell communication via these EVs might open novel pathways for a better understanding of CST in HCEC cultures.

Gene Signature-Based Development of ELISA Assays for Reproducible Qualification of Cultured Human Corneal Endothelial Cells.

PURPOSE To develop a method to qualify the function of cultured human corneal endothelial cells (cHCECs) applicable for clinical settings. METHODS The diversified gene and microRNA (miRNA) signatures in HCECs from a variety of tissue donors were confirmed by three-dimensional (3D) gene human miRNA profiling. These were compared with those of more than 20 cHCECs distinct in their cell morphology or culture lots. Candidate genes were selected after quantitative (q)RT-PCR validation, and gene products were assayed by ELISA. After three additional screening steps, final candidate cytokines for qualification were selected. RESULTS Gene and miRNA signatures among distinct cHCEC lots were greatly diversified compared with those among fresh tissues from different age donors. By comparing more than 20 lots of cultures, 32 candidate genes were assigned to be seemingly linked to distinct cHCEC morphologic features. The validation of candidate genes by qRT-PCR revealed the genes, either upregulated or downregulated, corresponding to morphologic variances in cHCECs (e.g., epithelial-mesenchymal transition or cell senescence). Further adding the ELISA results by Bio-Plex Human Cytokine 27-Plex Panel, 11 candidate cytokines suitable to qualify cHCEC function were selected. In consideration of the presence of these cytokines in the anterior chamber, IL-8, tissue inhibitors of metalloproteinases 1 (TIMP-1), monocyte chemotactic protein-1 (MCP-1), and platelet-derived growth factor-BB (PDGF-BB) were ultimately selected and applied in practice for the qualification of cHCECs actually used in our clinical cell-injection studies. CONCLUSIONS The specified cytokines properly discriminating the functional features of cHCECs indicates a correlation between profiling signatures and cell morphology.

Production of Homogeneous Cultured Human Corneal Endothelial Cells Indispensable for Innovative Cell Therapy

Purpose Cultured human corneal endothelial cells (cHCECs) are anticipated to become an alternative to donor corneas for the treatment of corneal endothelial dysfunction. The aim of this study was to establish proper culture protocols to successfully obtain a reproducibly homogeneous subpopulation (SP) with matured cHCEC functions and devoid of cell-state transition suitable for cell-injection therapy. Methods The presence of SPs in cHCECs was investigated in terms of surface cluster-of-differentiation (CD) marker expression level by flow cytometry, as combined analysis of CD markers can definitively specify the SP (effector cells) conceivably the most suitable for cell therapy among diverse SPs. The culture conditions were evaluated by flow cytometry in terms of the proportion (E-ratio) of effector cells designated by CD markers. Results Flow cytometry analysis identifying CD44-CD166+CD133-CD105-CD24-CD26- effector cells proved convenient and reliable for standardizing the culture procedures. To ascertain the reproducible production of cHCECs with E-ratios of more than 90% and with no karyotype abnormality, the preferred donor age was younger than 29 years. The continuous presence of Rho-associated protein kinase (ROCK)-inhibitor Y-27632 greatly increased the E-ratios, whereas the presence of transforming growth factor-beta/Smad-inhibitor SB431542 greatly reduced the number of recovered cHCECs. The seeding cell density during culture passages proved vital for maintaining a high E-ratio for extended passages. The continuous presence of ROCK-inhibitor Y-27632 throughout the cultures greatly improved the E-ratio. Conclusions Our findings elucidated the culture conditions needed to obtain reproducible cHCECs with high E-ratios, thus ensuring homogeneous cHCECs with matured functions for the treatment of corneal endothelial dysfunction.