A method of isolation and culture of microvascular endothelial cells from mouse skin

Isolating and cryopreserving pig skin cells for single-cell RNA sequencing study

The pig skin architecture and physiology are similar to those of humans. Thus, the pig model is very valuable for studying skin biology and testing therapeutics. The single-cell RNA sequencing (scRNA-seq) technology allows quantitatively analyzing cell types, compositions, states, signaling, and receptor-ligand interactome at single-cell resolution and at high throughput. scRNA-seq has been used to study mouse and human skins. However, studying pig skin with scRNA-seq is still rare. A critical step for successful scRNA-seq is to obtain high-quality single cells from the pig skin tissue. Here we report a robust method for isolating and cryopreserving pig skin single cells for scRNA-seq. We showed that pig skin could be efficiently dissociated into single cells with high cell viability using the Miltenyi Human Whole Skin Dissociation kit and the Miltenyi gentleMACS Dissociator. Furthermore, the obtained single cells could be cryopreserved using 90% FBS + 10% DMSO without causing additional cell death, cell aggregation, or changes in gene expression profiles. Using the developed protocol, we were able to identify all the major skin cell types. The protocol and results from this study are valuable for the skin research scientific community.

Effects of IL-1β and TNF-α on the Expression of P311 in Vascular Endothelial Cells and Wound Healing in Mice

Objective

This study aimed to define the role of interleukine-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the expression of P311 in vascular endothelial cells (VECs) and in wound healing.

Methods

DAPI staining, a CCK-8 assay, cell migration assay, and an angiogenesis assay were used to assess the effects exerted by TNF-α and IL-1β at various concentrations on morphology, proliferation, migration, and angiogenesis of VECs. Western blot (WB) and reverse transcription-polymerase chain reaction (RT-PCR) models were employed to observe the effects exerted by proteins related to the nuclear factor-kappa B (NF-κB) signaling pathway and P311 mRNA expression. Bioinformatics analysis was performed on the binding sites of P311 and NF-κB. Finally, to investigate the effects of IL-1β and TNF-α on wound healing and the length of new epithelium in mice, we established a full-thickness wound defect model in mice. Immunohistochemistry was used to measure changes in P311, proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), CD31 (platelet endothelial cell adhesion molecule-1, PECAM-1/CD31), as well as other related proteins.

Results

When levels of TNF-α and IL-1β were both 20 ng/ml, their effects on cell proliferation, cytoskeleton protein expression, cell migration, and angiogenesis were the greatest (P < 0.05). IL-1β and TNF-α at moderate concentrations effectively promoted P311 mRNA and p-NF-κB protein expression (P < 0.05), while p-NF-K b protein expression was decreased (P < 0.05). Luciferase assays showed that P311 expression was also relatively greater when stimulated at moderate concentrations (P < 0.05), while relative expression was significantly lower when the p-NF-K b inhibitor CAPE was added (P < 0.05). On 7-day wound healing rate comparison, the control, IL-1β, IL-1βab, TNF-α, and TNF-αab groups were 18, 37, 35, 39, and 36%, respectively, while control group + P311 siRNA was 31% (P < 0.05). New epithelial length, granulation tissue thickness, and number of blood vessels trends were also the same. In the control group, P311 showed lower relative expression levels than the others (P < 0.05). P311 relative expression levels trended as follows: control group > IL-1βab > IL-1β > TNF-αab > TNF-α (P < 0.05).

Conclusion

When IL-1β and TNF-α concentrations are moderate, they effectively promote the proliferation, expression, migration, and angiogenesis of VECs, possibly by promoting the expression of the NF-K b pathway and thereby promoting the expression of P311. In vitro experiments on mice suggest that P311 effectively promotes wound healing, and its mechanism may be closely related to PCNA, CD31, and VEGF.

Mesenchymal-endothelial transition-derived cells as a potential new regulatory target for cardiac hypertrophy

The role of Mesenchymal-endothelial transition (MEndoT) in cardiac hypertrophy is unclear. To determine the difference between MEndoT-derived and coronary endothelial cells is essential for understanding the revascularizing strategy in cardiac repair. Using lineage tracing we demonstrated that MEndoT-derived cells exhibit highly heterogeneous which were characterized with highly expression of endothelial markers such as vascular endothelial cadherin(VECAD) and occludin but low expression of Tek receptor tyrosine kinase(Tek), isolectin B4, endothelial nitric oxide synthase(eNOS), von Willebrand factor(vWF), and CD31 after cardiac hypertrophy. RNA-sequencing showed altered expression of fibroblast lineage commitment genes in fibroblasts undergoing MEndoT. Compared with fibroblasts, the expression of p53 and most endothelial lineage commitment genes were upregulated in MEndoT-derived cells; however, the further analysis indicated that MEndoT-derived cells may represent an endothelial-like cell sub-population. Loss and gain function study demonstrated that MEndoT-derived cells are substantial sources of neovascularization, which can be manipulated to attenuate cardiac hypertrophy and preserve cardiac function by improving the expression of endothelial markers in MEndoT-derived cells. Moreover, fibroblasts undergoing MEndoT showed significantly upregulated anti-hypertrophic factors and downregulated pro-hypertrophic factors. Therefore MEndoT-derived cells are an endothelial-like cell population that can be regulated to treat cardiac hypertrophy by improving neovascularization and altering the paracrine effect of fibroblasts.

P311 Deficiency Leads to Attenuated Angiogenesis in Cutaneous Wound Healing

P311 was identified to markedly promote cutaneous wound healing by our group. Angiogenesis plays a key role in wound healing. In this study, we sought to define the role of P311 in skin wound angiogenesis. It was noted that P311 was expressed in endothelial cells in the dermis of murine and human skin wounds. The expression of P311 was confirmed in cultured murine dermal microvascular endothelial cells (mDMECs). Moreover, it was found that knockout of P311 could attenuate the formation of tubes and motility of mDMECs significantly in vitro. In the subcutaneous Matrigel implant model, the angiogenesis was reduced significantly in P311 knockout mice. In addition, wound healing was delayed in P311 knockout mice compared with that in the wild type. Granulation tissue formation during the defective wound healing showed thinner and blood vessel numbers in wound areas in P311 knockout mice were decreased significantly. A reduction in VEGF and TGFβ1 was also found in P311 KO mice wounds, which implied that P311 may modulate the exprssion of VEGF and TGFβ1 in wound healing. Together, our findings suggest that P311 plays an important role in angiogenesis in wound healing.

VEGF165 induces differentiation of hair follicle stem cells into endothelial cells and plays a role in in vivo angiogenesis

Within the vascular endothelial growth factor (VEGF) family of five subtypes, VEGF165 secreted by endothelial cells has been identified to be the most active and widely distributed factor that plays a vital role in courses of angiogenesis, vascularization and mesenchymal cell differentiation. Hair follicle stem cells (HFSCs) can be harvested from the bulge region of the outer root sheath of the hair follicle and are adult stem cells that have multi-directional differentiation potential. Although the research on differentiation of stem cells (such as fat stem cells and bone marrow mesenchymal stem cells) to the endothelial cells has been extensive, but the various mechanisms and functional forms are unclear. In particular, study on HFSCs' directional differentiation into vascular endothelial cells using VEGF165 has not been reported. In this study, VEGF165 was used as induction factor to induce the differentiation from HFSCs into vascular endothelial cells, and the results showed that Notch signalling pathway might affect the differentiation efficiency of vascular endothelial cells. In addition, the in vivo transplantation experiment provided that HFSCs could promote angiogenesis, and the main function is to accelerate host-derived neovascularization. Therefore, HFSCs could be considered as an ideal cell source for vascular tissue engineering and cell transplantation in the treatment of ischaemic diseases.

Recent updates in experimental protocols for endothelial cells

Scleroderma (systemic sclerosis, SSc) is a multisystem autoimmune disease of unknown etiology. The disease is characterized by vascular disorder, activation of the immune system, and excessive deposition of matrix proteins in the skin and involved organs. The vascular disorder is believed to play a crucial role in disease pathogenesis. Endothelial injury and dysfunction, subsequent capillary loss and arteriolar wall thickness, are well documented in all involved organs. The resulting tissue hypoxia and ischemia fail to initiate new vessel formation leading to progressive loss of vasculature with no apparent replenishment. Issues related to endothelial injury/activation, dysfunction and failure of angio/vasculogenesis are central to the understanding of SSc vasculopathy. Isolation of endothelial cells and cells involved in the genesis of new vessels is enormously important in the investigation of mechanisms involved in SSc vasculopathy. Nevertheless, this goal has been difficult to achieve in view of the charac­teristic slow growth of endothelial cells, the high demand for growth factors and rapid growth of contaminating cells and the scarcity of circulating cells involved in angio/vasculogenesis hampered this line of investigation. Nonetheless, recent technologic progress in the last decade provided us with the tools to isolate vascular cells with an acceptable purity based on unique cell surface markers using immunoselection methods. The purpose of this review is to update the readers on current technical state-of-the-art methods of isolation and propagation of vascular cells. We wish that this review will spark interest in more investigations of this crucial phase of SSc pathogenesis.

Microvascular endothelial cells from preeclamptic women exhibit altered expression of angiogenic and vasopressor factors

Preeclampsia (PE) is a severe complication of pregnancy associated with maternal and fetal morbidity and mortality. The underlying pathophysiology involves maternal systemic vascular and endothelial dysfunction associated with circulating antiangiogenic factors, although the specific etiology of the disease remains elusive. Our aim was to investigate the maternal endothelium in PE by exploring the expression of genes involved with endothelial function in a novel platform of maternal primary endothelial cells. Adipose tissue was sampled at the time of caesarean section from both normal and preeclamptic patients. Maternal microvascular endothelial cells were isolated by tissue digestion and CD31 magnetic Dynabeads. Cell purity was confirmed by immunofluorescence microscopy and flow cytometry. Western analyses revealed VEGF activation of VEGF receptor 2 (VEGFR2) and ERK in primary cells. Quantitative PCR analyses revealed significantly altered mRNA levels of various genes involved with angiogenesis and blood pressure control in preeclamptic cells, including soluble fms-like tyrosine kinase-1, endoglin, VEGFR2, angiotensin receptor 1, and endothelin compared with cells isolated from normal pregnancies. Overall, maternal endothelial cells from preeclamptic patients exhibit extensive alteration of expression of factors associated with antiangiogenic and vasoconstrictive phenotypes, shedding light on the underlying mechanisms associated with the vascular dysfunction characteristic of PE.

Interleukin-17A promotes functional activation of systemic sclerosis patient-derived dermal vascular smooth muscle cells by extracellular-regulated protein kinases signalling pathway

INTRODUCTION

Dermal vascular smooth muscle cells (DVSMCs) are important for vascular wall fibrosis in microangiopathy of systemic sclerosis (SSc). T helper 17 cell-associated cytokines, particularly interleukin-17A (IL-17A), have been demonstrated to play a role in the pathogenesis of SSc. However, the effect of IL-17A on the DVSMCs in microangiopathy of SSc has not been established. In the present study, we investigated the effect of IL-17A on the SSc patient-derived DVSMCs.

METHODS

DVSMCs from patients with SSc and healthy subjects were incubated using IL-17A or serum derived from patients with SSc. Subsequently, the proliferation, collagen synthesis and secretion, and migration of DVSMCs were analysed using a cell counting kit-8 (CCK-8), dual-luciferase reporter assay, real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and transwell assay. The protein phosphorylation of signalling pathways in the process of IL-17A-mediated DVSMC activation was investigated and validated by specific signalling pathway inhibitor.

RESULTS

IL-17A and serum from patients with SSc could promote the proliferation, collagen synthesis and secretion, and migration of DVSMCs. IL-17A neutralising antibody could inhibit the IL-17A-induced activation of DVSMCs. Additionally, IL-17A induced the activation of extracellular-regulated protein kinases 1/2 (ERK1/2) in DVSMCs, and ERK1/2 inhibitor could block the IL-17A-elicited activation of DVSMCs.

CONCLUSIONS

Our results suggested that IL-17A derived from patients with SSc might induce the proliferation, collagen synthesis and secretion, and migration of DVSMCs via ERK1/2 signalling pathway, raising the likelihood that IL-17A and ERK1/2 might be promising therapeutic targets for the treatment of SSc-related vasculopathy.

Characterization of microvascular endothelial cells isolated from the dermis of adult mouse tails

Dermal microvascular endothelial cells (DMECs) play an important role in physiological and pathophysiological processes such as wound healing, cell differentiation, antigen-presentation, inflammation, tumor metastasis, and diabetes. The study of these processes requires a suitable and accessible in vitro model, such as murine DMECs (mDMECs). However, since these cells are difficult to isolate and propagate, some of their properties are not fully characterized. We isolated these cells from C57BL/6J adult mouse tail skin and purified them using magnetic sorting. Then, we tested several culture conditions and oxygen concentrations for mDMEC growth and propagation. After obtaining optimal culture conditions, we characterized the expression of EC markers and compared such expression with an established murine microvascular EC line (EOMA). Our results indicate that mDMECs isolated from mouse tails expressed most of the characteristic EC markers such as von Willebrand Factor (vWF), CD31, Tie1, Tie2, ANGPT1, ANGPT2, FLK-1, FLT-1, and VEGF-A. Further characterization demonstrated that these cells also expressed proteins involved in organogenesis such as bone morphogenetic proteins-2, -4 (BMP-2/-4), and their receptor (BMPR1A). Surprisingly, higher expression of vWF, ANGPT1, and BMP-2 was observed in mDMECs compared to EOMA cells. For mDMEC in vitro propagation, we found a twofold increase in cell proliferation in cells that grew at 1% O(2) compared to those cells that grew at standard 20% O(2.) Therefore, the method described herein for mDMECs isolation and propagation allowed us to analyze in more detail their biological properties that can be relevant for the study of pathological processes using mouse models.

Novel 14S,21-dihydroxy-docosahexaenoic acid rescues wound healing and associated angiogenesis impaired by acute ethanol intoxication/exposure

Acute ethanol intoxication and exposure (AE) has been known to impair wound healing and associated angiogenesis. Here, we found that AE diminished the formation of novel reparative lipid mediator 14S,21-dihydroxy-docosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid (14S,21-diHDHA) and its biosynthetic intermediate 14S-hydroxy-DHA (14S-HDHA) from docosahexaenoic acid (DHA) in murine wounds. However, AE did not reduce the formation of DHA and the intermediate 21-HDHA. These results indicate that in the biosynthetic pathways of 14S,21-diHDHA in wounds, AE suppresses the 14S-hydroxy-generating activity of 12-lipoxygenase-like (LOX-like), but does not suppress the 21-hydroxy-generating activity of cytochrome P450 and DHA-generating activities. The AE-suppression of 12-LOX-like activity was further confirmed by the diminished formation of 12-hydroxy-eicosatetraenoic acid in wounds under AE. Supplementing 14S,21-diHDHA to wounds rescued the AE-impaired healing and vascularization. 14S,21-diHDHA restored AE-impaired processes of angiogenesis in vitro: endothelial cell migration, tubulogenesis, and phosphorylation of p38 mitogen-activated protein kinase (MAPK). Taken together, the suppression of 14S,21-diHDHA formation is responsible, at least partially, for the AE-impairment of cutaneous wound healing and angiogenesis. Supplementing 14S,21-diHDHA to compensate its deficit in AE-impaired wounds rescues the healing and angiogenesis. These results provide a novel mechanistic insight for AE-impaired wound healing that involves the necessary roles of 14S,21-diHDHA. They also offer leads for developing 14S,21-diHDHA-related therapeutics to ameliorate AE-impairment of wound healing.

14S,21R-dihydroxydocosahexaenoic acid remedies impaired healing and mesenchymal stem cell functions in diabetic wounds

Treatment of diabetes-impaired wound healing remains a major unresolved medical challenge. Here, we identified suppressed formation of a novel reparative lipid mediator 14S,21R-dihydroxydocosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid (14S,21R-diHDHA) in cutaneous wounds of diabetic db/db mice. These results indicate that diabetes impedes the biosynthetic pathways of 14S,21R-diHDHA in skin wounds. Administration of exogenous 14S,21R-diHDHA to wounds in diabetic animals rescued healing and angiogenesis. When db/db mesenchymal stem cells (MSCs) were administered together with 14S,21R-diHDHA to wounds in diabetic animals, they coacted to accelerate wound re-epithelialization, granulation tissue formation, and synergistically improved vascularization. In the pivotal cellular processes of angiogenesis, 14S,21R-diHDHA enhanced VEGF release, vasculature formation, and migration of db/db dermal microvascular endothelial cells (DMVECs), as well as remedied paracrine angiogenic functions of db/db MSCs, including VEGF secretion and the promotion of DMVEC migration and vasculature formation. Our results show that 14S,21R-diHDHA activates the p38 MAPK pathway in wounds, db/db MSCs, and DMVECs. Overall, the impeded formation of 14S,21R-diHDHA described in this study suggests that diabetes could affect the generation of pro-healing lipid mediators in wound healing. By restoring wound healing and MSC functions, 14S,21R-diHDHA is a new lead for the development of better therapeutics used in treating wounds of diabetics.

Targeting angiogenesis in pancreatic cancer: rationale and pitfalls

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer responsible for over 20% of deaths due to gastrointestinal malignancies. PDAC is usually diagnosed at an advanced stage which, in part, helps to explain its high resistance to chemotherapy and radiotherapy. In addition, the cancer cells in PDAC have a high propensity to metastasize and to aberrantly express several key regulators of angiogenesis and invasion. Chemotherapy has only provided a modest impact on mean survival and often induces side effects. Targeting angiogenesis alone or in combination with other modalities should be investigated to determine if it may provide for increased survival.

MATERIALS AND METHODS

This review summarizes the alterations in PDAC that play a critical role in angiogenesis and provides an overview of current and therapeutic strategies that may be useful for targeting angiogenesis in this malignancy.

Endothelial nitric oxide synthase stimulates aneurysm growth in aged mice

BACKGROUND/AIMS

Age-associated changes in endothelial nitric oxide synthase (eNOS) expression have not been definitively linked to the pathophysiology of aortic aneurysms. We examined the role of eNOS in human patients and an age-appropriate mouse model.

METHODS

eNOS transcripts and immunodetectable protein were assessed by quantitative PCR and immunohistochemistry in human ascending thoracic aneurysms (n = 29) and referent aortae (n = 31). Carotid aneurysms were induced with CaCl2 in young adult (3 months) and aged (18 months) C57BL/6 and eNOS-knockout (eNOS-KO) mice.

RESULTS

eNOS transcripts and protein were reduced in human aneurysms compared with controls, although aortic eNOS expression also decreased with patient age. Aged wild-type mice had significantly larger aneurysm diameter than young adult mice. Aged wild-type mice had reduced eNOS transcripts and protein compared with young adult mice. Aged eNOS-KO mice had smaller aneurysms compared with aged wild-type mice but similar size aneurysms compared with young eNOS-KO and young wild-type mice.

CONCLUSION

eNOS expression is reduced in both aged human and aged mouse endothelium and eNOS expression is linked to aneurysm expansion in aged but not young adult mice. These findings support the relevance of age-associated changes in eNOS expression in clinical aneurysmal disease.

Vascular-specific quantification in an in vivo Matrigel chamber angiogenesis assay

The study of angiogenesis as a therapeutic target requires reliable in vivo assays that can provide physiologically relevant data. A murine in vivo Matrigel-based angiogenesis assay is presented here which includes the quantitative assessment of vascular-specific indicators of neovascularization. Matrigel containing 175 ng/ml bFGF is encapsulated in synthetic chambers which are implanted subcutaneously in C57/B16J mice. Ex vivo implants can be imaged to qualitatively view perfused vasculature within the chambers, or histologically processed to confirm the presence of vascular-specific tissue within the Matrigel. Viable cells are recovered from the excised chambers and quantified cytometrically using endothelial cell-specific markers CD34 and CD144, and for a marker of nucleated cells, Hoechst 33342. Thalidomide, 200 mg/kg/day, was tested using the assay and was found to inhibit angiogenesis by 46%. Angiogenesis inhibitors secreted by LL/M27 tumors were also characterized, where tumor-bearing mice showed a 73% inhibition of angiogenesis compared to tumor-free controls. Analysis of the number of nucleated cells in these samples failed to show a strong correlation with the number of endothelial cells, indicating that quantification of nonvascular-specific tissue in in vivo angiogenesis assays may not be sufficient. This new assay provides an objective, comprehensive determination of the vasculature-specific response of both endogenous and exogenous angiogenesis inhibitors in vivo, and also creates new opportunities for obtaining primary murine endothelial cells.