Mitochondrial elongation in retinal vascular cells as a result of exposure to high-glucose conditions

Abstract

Purpose : Diabetic retinopathy results in the proliferation of endothelial cells and excessive vascularization in the retina, leading to blindness. In diabetic mice, these structural changes succeed changes in oxygen metabolism in the retinal microvasculature. This suggests that changes in mitochondrial function may precede diabetic retinopathy.

Methods : To investigate intracellular mitochondrial changes, we used Stochastic Optical Reconstruction Microscopy (STORM) to visualize mitochondrial morphology variations in primary mouse retinal pericyte (PC) and endothelial cells (EC) with and without five-day incubation in a high-glucose culture medium. This allowed us to visualize mitochondrial morphology down to a ~50nm resolution level. We then segmented and analyzed the images, looking at size, shape, and distributional changes in the mitochondria over different conditions, using an unpaired t-test to compare between groups.

Results : Preliminary results suggest that in primary PC cells treated with glucose, there is a significant level of mitochondrial elongation compared to untreated PC cells. The median length of mitochondria goes increased from 0.41 to 0.90 µm (p<0.05) between the control and glucose treated cells. Furthermore, the median total area of each 2D cell image covered with mitochondria increased from 208 to 298 µm² (p<0.05) with no corresponding increase in cytoplasm or nucleus size and with no corresponding increase in the number of mitochondria.

Conclusions : The elongation of mitochondria in the PC suggests an increased metabolic rate in these cells after glucose treatment. Future studies could explore the relationship between PC metabolic rate and the level of vascularization in the retina.

This is a 2021 ARVO Annual Meeting abstract.

 

Figure 1. A panel of retinal vascular cells with and without glucose treatment (a) A PC cell without glucose treatment showing a fragmented mitochondrial morphology. (b) A PC cell after glucose treatment showing an elongated mitochondrial morphology. (c) An EC cell without glucose treatment showing a mostly fragmented mitochondrial morphology. (d) An EC cell after glucose treatment showing a mostly fragmented mitochondrial morphology. All cell images were captured using STORM and labeled using an antibody against TOM20.