A single-cell transcriptome atlas of the adult human retina.

The retina is a specialized neural tissue that senses light and initiates image processing. Although the functional organization of specific retina cells has been well studied, the molecular profile of many cell types remains unclear in humans. To comprehensively profile the human retina, we performed single-cell RNA sequencing on 20,009 cells from three donors and compiled a reference transcriptome atlas. Using unsupervised clustering analysis, we identified 18 transcriptionally distinct cell populations representing all known neural retinal cells: rod photoreceptors, cone photoreceptors, Müller glia, bipolar cells, amacrine cells, retinal ganglion cells, horizontal cells, astrocytes, and microglia. Our data captured molecular profiles for healthy and putative early degenerating rod photoreceptors, and revealed the loss of MALAT1 expression with longer post-mortem time, which potentially suggested a novel role of MALAT1 in rod photoreceptor degeneration. We have demonstrated the use of this retina transcriptome atlas to benchmark pluripotent stem cell-derived cone photoreceptors and an adult Müller glia cell line. This work provides an important reference with unprecedented insights into the transcriptional landscape of human retinal cells, which is fundamental to understanding retinal biology and disease.

Supply and Demand of Domestic Corneal Tissue and Its Implications on Export Potential-Using Australia as an Example.

PURPOSE: Corneal tissue importation is only possible if another country is able to export corneas without impacting its own domestic demand. Currently, there is little evidence to indicate whether export nations have such surplus capacity and in a position to export. To explore this concept, we examined our nation, Australia, which is reported to routinely decline donations because of its ability to meet domestic corneal transplant demand. Our research offers insights and opportunities for Australia and other nations to evaluate their domestic and international supply and allocation of corneal tissue in this space. METHOD: We collated 12 months of data on collected and noncollected donations, through participating Australian Eye Banks. The explanation of why some known donors were declined or not pursued indicated if demand was met and potential surplus-for-export levels. RESULTS: There were 7.5% (n = 11,889) of deaths in Australia that were notified to Australian Eye Banks during our reporting period. Of those, 9.3% (n = 1106/11,889) were recovered and allocated, 15.7% (n = 1863/11,889) were known but declined, and 75% (n = 8920/11,889) were not pursued. Of those that were declined, 64.3% (n = 1197/1863) were declined because of limitations with service/manpower at the eye bank, whereas 35.7% (n = 666/1863) were declined because demand was met. CONCLUSIONS: Australia did not meet demand all the time, during our data period. There were adequate quantities of potential donors to support increasing recovery for domestic allocation and provide for exportation without hindrance to Australian demand. Further examination of domestic supply and demand cycles and the export process is required before routine exportation.

Histopathological evaluation of anterior lamellar corneal tissue-on/-off storage conditions on DSAEK donor tissue after storage in organ culture.

PURPOSE: To compare the quality of corneal endothelium of precut Descemet-stripping automated endothelial keratoplasty (DSAEK) tissue when transported with and without the anterior lamellar corneal tissue (ALCT) when organ-culture corneal storage methods are used. METHODS: After microkeratome-assisted excision of anterior corneal lamella, five pairs of corneas (10 eyes) were stored either with the ALCT on the stroma (five eyes) or with ALCT off the stroma (five eyes) in organ-culture medium. Three pairs (six matched corneas) were left in the transport medium for 24 h prior to the microkeratome cut. Two pairs (four matched corneas) were left in the transport medium for 48 h prior to the microkeratome cut. All cuts were performed using a 300 (four eyes) or 350 (six eyes) microns head. A vital dye assay (alizarin red S and trypan blue) was used to identify devitalized and necrotic endothelial cells. RESULTS: In all matched cases, there was no difference between the endothelial cell appearance with or without the anterior corneal lamella. In all cases, there was no evidence for trypan blue stained cells beyond that normally seen on acceptable transplantable corneas and there was no evidence of loss of cells or any lifting of Descemet's membrane. CONCLUSIONS: There is no difference between the quality of the donor endothelial cell appearance with ALCT-on or -off when the donor cornea is stored using the organ-culture system of corneal storage. Organ-culture storage system is a safe and effective system in regard to preparation and transport of donor lenticules for DSAEK.