The Biologic Character of Donor Corneal Endothelial Cells Influences Endothelial Cell Density Post Successful Corneal Transplantation

Purpose: Corneal endothelial cell density (ECD) gradually decreases after corneal transplantation by unknown biologic, biophysical, or immunologic mechanism. Our purpose was to assess the association between donor corneal endothelial cell (CEC) maturity in culture and postoperative endothelial cell loss (ECL) after successful corneal transplantation. Design: Prospective cohort study. Participants: This cohort study was conducted at Baptist Eye Institute, Kyoto, Japan, between October 2014 and October 2016. It included 68 patients with a 36-month follow-up period who had undergone successful Descemet stripping automated endothelial keratoplasty (DSAEK) or penetrating keratoplasty. Methods: Human CECs (HCECs) from remaining peripheral donor corneas were cultured and evaluated for maturity by surface markers (CD166+, CD44−/dull, CD24−, and CD105−) using fluorescence-activated cell sorting. Postoperative ECD was assessed according to the mature-differentiated HCEC contents: high-maturity group: > 70%, middle-maturity group: 10% to 70%, low-maturity group: < 10%. The successful rate of ECD maintained at 1500 cells/mm2 at 36 months postoperative was analyzed using the log-rank test. Main Outcome Measures: Endothelial cell density and ECL at 36 months postoperative. Results: The 68 included patients (mean [standard deviation] age 68.1 [13.6] years, 47.1% women, 52.9% DSAEK). The high, middle, and low-maturity groups included 17, 32, and 19 eyes, respectively. At 36 months postoperative, the mean (standard deviation) ECD significantly decreased to 911 (388) cells/mm2 by 66% in the low-maturity group, compared with 1604 (436) by 40% and 1424 (613) cells/mm2 by 50% in the high and middle-maturity groups (P < 0.001 and P = 0.007, respectively) and the low-maturity group significantly failed to maintain ECD at 1500 cells/mm2 at 36 months postoperative (P < 0.001). Additional ECD analysis for patients who underwent DSAEK alone displayed a significant failure to maintain ECD at 1500 cells/mm2 at 36 months postoperative (P < 0.001). Conclusions: The high content of mature-differentiated HCECs expressed in culture by the donor peripheral cornea was coincident with low ECL, suggesting that a high-maturity CEC content predicts long-term graft survival. Understanding the molecular mechanism for maintaining HCEC maturity could elucidate the mechanism of ECL after corneal transplantation and aid in developing effective interventions. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references

The Interplay Between Metabolites and MicroRNAs in Aqueous Humor to Coordinate Corneal Endothelium Integrity

Purpose: The purpose of the study was to clarify the interplay between metabolites and microRNAs (miRs) in the aqueous humor (AqH) of bullous keratopathy (BK) patients to retain human corneal endothelium (HCE) integrity. Design: Prospective, comparative, observational study. Participants: A total of 55 patients with BK and 31 patients with cataract (Cat) as control. Methods: A biostatic analysis of miRs and metabolites in the AqH, hierarchical clustering, and a least absolute shrinkage and selection operator (Lasso) analysis were employed. The miR levels in AqH of BK (n = 18) and Cat (n = 8) patients were determined using 3D-Gene human miR chips. Hierarchical clusters of metabolites detected by liquid chromatography–mass spectrometry or gas chromatography–mass spectrometry in AqH specimens from 2 disease groups, BK (total n = 55) and Cat (total n = 31), were analyzed twice to confirm the reproducibility. The analytical procedure applied for investigating the association between metabolites and miRs in AqH was the exploratory data analysis of biostatistics to avoid any kind of prejudice. This research procedure includes a heat-map, cluster analysis, feature extraction techniques by principal component analysis, and a regression analysis method by Lasso. The cellular and released miR levels were validated using reverse transcription polymerase chain reaction and mitochondria membrane potential was assessed to determine the functional features of the released miRs. Main Outcome Measures: Identification of interacting metabolites and miRs in AqH attenuating HCE degeneration. Results: The metabolites that decreased in the AqH of BK patients revealed that 3-hydroxyisobutyric acid (HIB), 2-aminobutyric acid (AB) and branched-chain amino acids, and serine were categorized into the same cluster by hierarchical clustering of metabolites. The positive association of HIB with miR-34a-5p was confirmed (P = 0.018), and the Lasso analysis identified the interplay between miR-34a-5p and HIB, between miR-24-3p and AB, and between miR-34c-5p and serine (P = 0.041, 0.027, and 0.009, respectively). 3-hydroxyisobutyric acid upregulated the cellular miR-34a expression, mitochondrial membrane potential, and release of miR-184 in dedifferentiated cultured HCE cells. Conclusions: Metabolites and miRs in AqH may synchronize in ensuring the integrity of the HCE to maintain efficient dehydration from the stroma. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references