Organ culture, but not hypothermic storage, facilitates the repair of the corneal endothelium following mechanical damage

Abstract

ABSTRACT.Purpose: To evaluate the reparative capacity of the mechanically injured endothelium of corneas stored under organ culture (OC) or hypothermic conditions. Methods: The central endothelium of 12 pairs of human corneas with similar endothelial parameters was damaged to create a 1 mm 2 lesion. One cornea from each pair was stored under OC and one under hypothermic conditions. The endothelial cell density (ECD), coefficient of variation, hexagonality and percentage of dead cells were assessed before and after damage and on days 7, 14, 21 and 28 of storage. Results: The mean ECD of corneas subsequently stored under OC or hypothermic conditions was 2764 ⁄ mm 2 . Immediately after damage, a denuded Descemet's membrane with a few remaining dead cells was observed at the injured area. After 7 days of storage under OC conditions, almost no dead cells were observed at the place of injury. A non-significant worsening of the qualitative parameters (polymegatism and pleomorphism) was found. After 14 days, ECD was 1933 ⁄ mm 2 and 2478 ⁄ mm 2 centrally and pericentrally, respectively. Similar values were found after 21 and 28 days of storage. The lesions with remnant dead cells persisted throughout hypothermic preservation. From day 14 the corneas became cloudy and in poor condition, while the pericentral ECD was 2523 ⁄ mm 2 . Conclusion: The reparative capacity of the cornea is maintained under OC but not under hypothermic conditions. For corneas containing dead endothelial cells, OC is therefore the method of choice because it may improve the quality of the stored tissue.

Effect of Low-Temperature Preservation in Optisol-GS on Preloaded, Endothelium-Out DMEK Grafts

“…Conversely, a rearrangement of the endothelial mosaic can be observed following a metabolic activation triggered by storage at higher temperatures, as shown in previous studies on epithelial cells [29,30]. This could explain why a progressive ECD variation was found in tissues preserved at different temperatures, such as in Group A compared to Group C, an effect likely due to endothelial repair reactivation caused by increased temperatures [31]. Finally, studies on cultured endothelial cells show that the ox-idative stress generated by low storage temperatures might be particularly damaging to the mitochondria-rich endothelial cell [24,32].…”

“…To date, two main storage systems of corneal tissue have been developed: cold storage, mainly used in America and Asia, maintains the cornea between 2 • C and 8 • C for a maximum of 14 days, while Organ Culture preservation, which uses room temperature up to 31-37 • C for storage of corneas, can preserve the tissues for up to 28 days [1,18,23]. The advantages of cold storage (no microbiology, no serum, less cost and storing space, ease of transport) must be weighed against those of organ culture, which is more technically difficult and time-consuming but can support cell metabolism under physiologic conditions and maintain cell viability for longer periods of time [20,23,24,30,31].…”

Effect of Low-Temperature Preservation in Optisol-GS on Preloaded, Endothelium-Out DMEK Grafts

“…Conversely, a rearrangement of the endothelial mosaic can be observed following a metabolic activation triggered by storage at higher temperatures, as shown in previous studies on epithelial cells [29,30]. This could explain why a progressive ECD variation was found in tissues preserved at different temperatures, such as in Group A compared to Group C, an effect likely due to endothelial repair reactivation caused by increased temperatures [31]. Finally, studies on cultured endothelial cells show that the ox-idative stress generated by low storage temperatures might be particularly damaging to the mitochondria-rich endothelial cell [24,32].…”

“…To date, two main storage systems of corneal tissue have been developed: cold storage, mainly used in America and Asia, maintains the cornea between 2 • C and 8 • C for a maximum of 14 days, while Organ Culture preservation, which uses room temperature up to 31-37 • C for storage of corneas, can preserve the tissues for up to 28 days [1,18,23]. The advantages of cold storage (no microbiology, no serum, less cost and storing space, ease of transport) must be weighed against those of organ culture, which is more technically difficult and time-consuming but can support cell metabolism under physiologic conditions and maintain cell viability for longer periods of time [20,23,24,30,31].…”

Endothelial Cell Density Before and After the Preparation of Corneal Lamellae for Descemet Membrane Endothelial Keratoplasty With a Stromal Rim

“…This could be explained by a greater sensitivity to mechanical trauma in corneas with a relatively lower ECD. 17 OC storage provides time for the elimination of DC and the repair of denuded areas by the surrounding cells, 21,22 which, in our study, is reflected in a significant decrease in %DC after 48 hours of storage in both groups compared with that immediately after preparation.…”

Endothelial Cell Viability after DMEK Graft Preparation

“……”

Effect of Low-Temperature Preservation in Optisol-GS on Preloaded, Endothelium-Out DMEK Grafts

“…Conversely, a rearrangement of the endothelial mosaic can be observed following a metabolic activation triggered by storage at higher temperatures, as shown in previous studies on epithelial cells [29,30]. This could explain why a progressive ECD variation was found in tissues preserved at different temperatures, such as in Group A compared to Group C, an effect likely due to endothelial repair reactivation caused by increased temperatures [31]. Finally, studies on cultured endothelial cells show that the ox-idative stress generated by low storage temperatures might be particularly damaging to the mitochondria-rich endothelial cell [24,32].…”

“…To date, two main storage systems of corneal tissue have been developed: cold storage, mainly used in America and Asia, maintains the cornea between 2 • C and 8 • C for a maximum of 14 days, while Organ Culture preservation, which uses room temperature up to 31-37 • C for storage of corneas, can preserve the tissues for up to 28 days [1,18,23]. The advantages of cold storage (no microbiology, no serum, less cost and storing space, ease of transport) must be weighed against those of organ culture, which is more technically difficult and time-consuming but can support cell metabolism under physiologic conditions and maintain cell viability for longer periods of time [20,23,24,30,31].…”

Endothelial Cell Density Before and After the Preparation of Corneal Lamellae for Descemet Membrane Endothelial Keratoplasty With a Stromal Rim

“…This could be explained by a greater sensitivity to mechanical trauma in corneas with a relatively lower ECD. 17 OC storage provides time for the elimination of DC and the repair of denuded areas by the surrounding cells, 21,22 which, in our study, is reflected in a significant decrease in %DC after 48 hours of storage in both groups compared with that immediately after preparation.…”

Endothelial Cell Viability after DMEK Graft Preparation

“……”

Effect of Low-Temperature Preservation in Optisol-GS on Preloaded, Endothelium-Out DMEK Grafts

“…Conversely, a rearrangement of the endothelial mosaic can be observed following a metabolic activation triggered by storage at higher temperatures, as shown in previous studies on epithelial cells [29,30]. This could explain why a progressive ECD variation was found in tissues preserved at different temperatures, such as in Group A compared to Group C, an effect likely due to endothelial repair reactivation caused by increased temperatures [31]. Finally, studies on cultured endothelial cells show that the ox-idative stress generated by low storage temperatures might be particularly damaging to the mitochondria-rich endothelial cell [24,32].…”

“…To date, two main storage systems of corneal tissue have been developed: cold storage, mainly used in America and Asia, maintains the cornea between 2 • C and 8 • C for a maximum of 14 days, while Organ Culture preservation, which uses room temperature up to 31-37 • C for storage of corneas, can preserve the tissues for up to 28 days [1,18,23]. The advantages of cold storage (no microbiology, no serum, less cost and storing space, ease of transport) must be weighed against those of organ culture, which is more technically difficult and time-consuming but can support cell metabolism under physiologic conditions and maintain cell viability for longer periods of time [20,23,24,30,31].…”

Endothelial Cell Density Before and After the Preparation of Corneal Lamellae for Descemet Membrane Endothelial Keratoplasty With a Stromal Rim

“…This could be explained by a greater sensitivity to mechanical trauma in corneas with a relatively lower ECD. 17 OC storage provides time for the elimination of DC and the repair of denuded areas by the surrounding cells, 21,22 which, in our study, is reflected in a significant decrease in %DC after 48 hours of storage in both groups compared with that immediately after preparation.…”

Endothelial Cell Viability after DMEK Graft Preparation

“……”