Single-cell RNA-seq and bulk-seq identify RAB17 as a potential regulator of angiogenesis by human dermal microvascular endothelial cells in diabetic foot ulcers

Background:Angiogenesis is crucial in diabetic wound healing and is often impaired in diabetic foot ulcers(DFUs).Human dermal microvascular endothelial cells(HDMECs)are vital components in dermal angiogenesis;however,their functional and transcriptomic characteristics in DFU patients are not well understood.This study aimed to comprehensively analyse HDMECs from DFU patients and healthy controls and find the potential regulator of angiogenesis in DFUs.Methods:HDMECs were isolated from skin specimens of DFU patients and healthy controls via magnetic-activated cell sorting.The proliferation,migration and tube-formation abilities of the cells were then compared between the experimental groups.Both bulk RNA sequencing(bulk-seq)and single-cell RNA-seq(scRNA-seq)were used to identify RAB17 as a potential marker of angiogenesis,which was further confirmed via weighted gene co-expression network analysis(WGCNA)and least absolute shrink and selection operator(LASSO)regression.The role of RAB17 in angiogenesis was examined through in vitro and in vivo experiments.Results:The isolated HDMECs displayed typical markers of endothelial cells.HDMECs isolated from DFU patients showed considerably impaired tube formation,rather than proliferation or migration,compared to those from healthy controls.Gene set enrichment analysis(GSEA),fGSEA,and gene set variation analysis(GSVA)of bulk-seq and scRNA-seq indicated that angiogenesis was downregulated in DFU-HDMECs.LASSO regression identified two genes,RAB17 and CD200,as characteristic of DFU-HDMECs;additionally,the expression of RAB17 was found to be significantly reduced in DFU-HDMECs compared to that in the HDMECs of healthy controls.Overexpression of RAB17 was found to enhance angiogenesis,the expression of hypoxia inducible factor-1α and vascular endothelial growth factor A,and diabetic wound healing,partially through the mitogen-activated protein kinase/extracellular signal-regulated kinase signalling pathway.Conclusions:Our findings suggest that the impaired angiogenic capacity in DFUs may be related to the dysregulated expression of RAB17 in HDMECs.The identification of RAB17 as a potential molecular target provides a potential avenue for the treatment of impaired angiogenesis in DFUs.

Functional states of resident vascular stem cells and vascular remodeling

Recent evidence indicates that different types of vascular stem cells （VSCs） reside within the mural layers of arteries and veins. The precise identities of these resident VSCs are still unclear; generally, postnatal vasculature contains multilineage stem cells and vascular cell lineage-specific progenitor/stem cells which may participate in both vascular repair and lesion formation. However, the underlying mechanism remains poorly understood. In this review, we summarize the potential molecular mechanisms, which may control the quiescence and activation of resident VSCs and highlight a notion that the differential states of resident VSCs are directly linked to vascular repair or lesion formation.

Graphene-incorporated hyaluronic acid-based hydrogel as a controlled Senexin A delivery system

Perivascular delivery of therapeutic agents against established aetiologies for occlusive vascular remodelling has great therapeutic potential for vein graft failure.However,none of the perivascular drug delivery systems tested experimentally have been translated into clinical practice.In this study,we established a novel strategy to locally and sustainably deliver the cyclin-dependent kinase 8/19 inhibitor Senexin A(SenA),an emerging drug candidate to treat occlusive vascular disease,using graphene oxide-hybridised hyaluronic acid-based hydrogels.We demonstrated an approach to accommodate SenA in hyaluronic acid-based hydrogels through utilising graphene oxide nanosheets allowing for non-covalent interaction with SenA.The resulting hydrogels produced sustained delivery of SenA over 21 days with tunable release kinetics.In vitro assays also demonstrated that the hydrogels were biocompatible.This novel graphene oxide-incorporated hyaluronic acid hydrogel offers an optimistic outlook as a perivascular drug delivery system for treating occlusive vascular diseases,such as vein graft failure.