A Single-Cell Survey of Cellular Heterogeneity in Human Great Saphenous Veins

Abstract

Background: The great saphenous vein (GSV) is the most commonly used conduit for coronary arterial bypass graft. However, the status of the GSV, including metabolic dysfunction such as diabetes mellitus (DM) complication, is strongly associated with vein graft failure (VGF). To date, the molecular mechanism underlying VGF remains elusive. Detailed characterization of the cellular components and corresponding expression regulation in GSVs would be of great importance for clinical decision making to reduce VGF. Methods: To this end, we performed single-cell RNA sequencing to delineate cellular heterogeneity in three human GSV samples. Results: Scrutinization of cellular composition and expression revealed cell diversity in human GSVs, particularly endothelial cells (ECs). Our results unraveled that functional adaptation drove great expression differences between venous ECs and valvular ECs. For instance, cell surface receptor ACKR1 demarcated venous Ecs, whereas ACRK3/ACKR4 were exclusively expressed by valvular ECs. Differential gene expression analysis suggested that genes highly expressed in venous ECs were mainly involved in vasculature development and regulation of leukocyte adhesion, whereas valvular ECs have more pronounced expression of genes participating in extracellular matrix organization, ossification and platelet degranulation. Of note, pseudo-time trajectory analysis provided in silico evidence indicating that venous ECs, valvular ECs and lymphatic vessels were developmentally connected. Further, valvular ECs might be an importance source for lymphatic vessel differentiation in adults. Additionally, we found a venous EC subset highly expressing IL6, which might be associated with undesirable prognosis. Meanwhile, we identified a population of ANGPTL7+ fibroblasts (FBs), which may be profibrotic and involved in insulin resistance in human GSVs. Additionally, our data suggest that immune cells only accounted for a small fraction, most of which were macrophages. By assessing the intertwined remodeling in metabolic dysfunction that potentially increases the gene expression regulatory network in mural cells and leukocytes, we found that transcription factor KLF9 likely operated a proinflammatory program, inducing the transcription of metallothionein proteins in two mural cell subsets and proinflammatory immune cells. Lastly, cellular communication analysis revealed that proinflammatory signaling, including TRAIL, PVR, CSF and GDF, were uniquely activated in patients with metabolic dysfunction. Conclusions: Our results identified critical cell-specific responses and cellular interactions in GSVs. Beyond serving as a repertoire, this work illustrates multifactorial likelihood of VGF.

The intricate cellular ecosystem of human peripheral veins as revealed by single-cell transcriptomic analysis

“…This secretory population, characterized by high APOD expression, was also widely distributed throughout the wall ( Fig 4B , S8B Fig ). Lastly, a small ANGPTL7 + fibroblast population (284 cells; Fig 4A ) with potential pro-fibrotic effects [ 66 ] was detected in agreement with previous studies [ 6 ].…”

“…The proportion of ECs ranged from 7.8 to 10.1% across the 4 veins analyzed ( Fig 1C ), for a total of 1,695 cells out of 20,006 in the focused uniform manifold approximation and projection (UMAP) plot ( Fig 2A ). These subdivided into five groups corresponding to arteriovenous zonation phenotypes annotated elsewhere [ 6 , 28 – 30 ]: EC1 [arteriolar-like], 215 cells; EC2 [capillary-like], 400; EC3 [venous-like], 712; EC4 [valvular-like], 257; and EC5 [lymphatic-like], 111 ( Fig 2 ). Canonical markers in common among all EC subsets were CDH5 , CLDN5 , ERG , PECAM1 , and VWF ( Fig 1D ), while markers characterizing each population are presented in S3A Fig and Table 1 .…”

Single cell transcriptome analysis of cavernous tissues reveals the key roles of pericytes in diabetic erectile dysfunction

“…Since the marker genes of pericytes and smooth muscle cells often overlap, and their expression patterns are tissue-specific, identifying suitable in vivo markers to accurately interpret transcriptional and phenotypic changes in these cell types is of utmost importance (Chasseigneaux et al, 2018, Kumar et al, 2017, Smyth et al, 2018. Recent studies have identified pericyte-specific markers in different tissues using single-cell RNA sequencing (Baek et al, 2022, Sun et al, 2022, enabling characterization of various cell types and their cell-cell communication. In this study, a single-cell transcriptome analysis was performed to examine the cellular heterogeneity in erectile dysfunction caused by diabetes.…”

Single-cell transcriptome analysis of cavernous tissues reveals the key roles of pericytes in diabetic erectile dysfunction

“…Since the marker genes of pericytes and SMCs often overlap, and their expression patterns are tissue-specific, identifying suitable in vivo markers to accurately interpret transcriptional and phenotypic changes in these cell types is of utmost importance ( Chasseigneaux et al, 2018 ; Kumar et al, 2017 ; Smyth et al, 2018 ). Recent studies have identified pericyte-specific markers in different tissues using single-cell RNA sequencing ( Baek et al, 2022 ; Sun et al, 2022 ), enabling characterization of various cell types and their cell-cell communication. In this study, a single-cell transcriptome analysis was performed to examine the cellular heterogeneity in ED caused by diabetes.…”