(VP103) SPATIAL TRANSCRIPTOMIC ANALYSIS OF MICROVASCULAR ENDOTHELIAL CELLS IN DIABETIC AND NON-DIABETIC MICE: INSIGHT INTO DIFFERENTIAL RESPONSES TO HYPERGLYCEMIA IN DIFFERENT TARGET ORGANS OF DIABETES

Background: Diabetes causes chronic microvascular complications such as diabetic retinopathy, cardiomyopathy, and nephropathy. Microvascular endothelial cells (MECs) are the centerpiece of these microvascular diabetic complications because they are more susceptible to hyperglycemia and are constantly in direct contact with high glucose in the blood. Despite being the same cell type, MECs from different tissue contexts are influenced by tissue-specific factors, leading to functional and phenotypical differences, and resulting in differing in outcomes across different complications. A better understanding of the basal differences, tissue-specific MEC responses, and common responses to hyperglycemia will improve our understanding of diabetic complications and may inform better approaches to treatment and management.

METHODS AND RESULTS: Diabetes was induced in 6-week-old C67BL/6 mice using streptozotocin. Diabetic and age-matched non-diabetic mice were sacrificed after 2 months. Eyes, kidneys, and hearts were harvested. Nanostring Digital Spatial Profiling was done in order to assess gene expression in MECs from these tissues. Briefly, tissues were sectioned and immunohistochemically stained for a structural endothelial marker, CD31, then treated with mouse-specific ISH probes hybridized to UV-cleavable barcode sequences. Barcode from CD31+ cells corresponding to microvessels were UV-cleaved, retrieved, and quantified to generate an EC-specific spatial transcriptomic profile. Data were analyzed using the GeoMx DSP analysis suite.

Results: Gene expression profiles of retinal, renal, and cardiac MECs were different in non-diabetic mice. Diabetes caused substantial changes in transcriptomic profiles in all MEC types, with the renal MECs having the largest number of significantly changed genes and significantly enriched pathways, and retinal MECs having the least. More pathways were upregulated rather than downregulated in response to hyperglycemia in diabetes in all MEC types. Most significantly changed genes were unique to each MEC type, but significantly enriched pathways showed slightly more similarity across MEC types.

Conclusion: Due to being in different organ contexts, MECs from different tissues are transcriptomically distinct from one another in the normal, non-diabetic, state. Diabetes causes changes across all MEC types, but the responses are largely unique to each type of MEC. Genes and pathways that are commonly altered by glucose across retinal, renal, and cardiac MECs could represent key targets in the management or treatment of chronic microvascular diabetic complications.