CoCl2 Administration to Vascular MSC Cultures as an In Vitro Hypoxic System to Study Stem Cell Survival and Angiogenesis

Extra villous trophoblast-derived PDL1 can ameliorate macrophage inflammation and promote immune adaptation associated with preeclampsia

INTRODUCTION

Severe preeclampsia (sPE) is a systemic syndrome that may originate from chronic inflammation. Maintaining maternal-fetal hemostasis by the co-inhibitory molecule programmed death ligand 1 (PDL1) can be favorable for ameliorating inflammation from immune cells. Apart from programmed death 1 (PD1) expression, decidual macrophages (dMs) produce inflammatory cytokines, in response to cells which express PDL1. However, strong evidence is lacking regarding whether the PDL1/PD1 interaction between trophoblasts and decidual macrophages affects inflammation during sPE development.

METHODS

To determine whether the trophoblast-macrophage crosstalk via the PDL1/PD1 axis modulates the inflammatory response in sPE-like conditions, at first, maternal-fetal tissues from sPE and normal patients were collected, and the PDL1/PD1 distribution was analyzed by Western blot, immunohistochemistry/ immunofluorescence and flow cytometry. Next, a coculture system was established and flow cytometry was used to identify how PDL1 was involved in macrophage-related inflammation under hypoxic stress. Transcriptional analysis was performed to clarify the inflammation-associated pathway induced by the PDL1/PD1 interaction. Finally, the Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) mouse model was used to examine the effect of PDL1 on macrophage-related inflammation by measuring PE-like symptoms.

RESULTS

In maternal-fetal tissue from sPE patients, placental extravillous trophoblasts (EVTs) and dMs had a surprisingly increase of PDL1 and PD1 expression, respectively, accompanied by a higher percentage of CD68 +CD86 + dMs. In vitro experiments showed that trophoblast-derived PDL1 under hypoxia interacted with PD1 on CD14 +CD80 +macrophages, leading to suppression of inflammation through the TNFα-p38/NFκB pathway. Accordingly, the PE-like mouse model showed a reversal of PE-like symptoms and a reduced F4/80 + CD86 + macrophage percentage in the uterus in response to recombinant PDL1 protein administration, indicating the protective effect of PDL1.

DISCUSSION

Our results initially explained an immunological adaptation of trophoblasts under placental hypoxia, although this protection was insufficient. Our findings suggest the possible capacity of modulating PDL1 expression as a potential therapeutic strategy to target the inflammatory response in sPE.

Trophoblast Exosomal UCA1 Induces Endothelial Injury through the PFN1-RhoA/ROCK Pathway in Preeclampsia: A Human-Specific Adaptive Pathogenic Mechanism

Preeclampsia is regarded as an evolution-related disease that has only been observed in humans and our closest relatives, and the important factor contributing to its pathogenesis is endothelial dysregulation secondary to a stressed placenta. Hypoxia-inducible factor 1 subunit alpha (HIF1α), a highly conserved molecule in virtually all mammals, is regarded as a crucial regulator of the hypoxia adaptation and evolution. Persistent high expression of HIF1α in the placenta is one of the pathogenic mechanisms of preeclampsia. Therefore, human-specific molecules should link increased HIF1α to preeclampsia. We reported that urothelial cancer associated 1 (UCA1) is a potential mediator because it is a human-specific long noncoding RNA (lncRNA) that is upregulated in placental tissues and maternal serum from women with preeclampsia and is regulated by HIF1α. The cellular HIF1α-UCA1 pathway promoted the adaptation of trophoblasts to hypoxia by inducing vascular endothelial growth factor (VEGF) secretion and changes in the levels of key enzymes in glycolysis. On the other hand, circulating exosomal UCA1 secreted from stressed trophoblasts induced vascular endothelial dysfunction, especially excess ROS production, as measured by exosome extraction and a coculture system. At the molecular level, UCA1 physically bound to ubiquitin-specific peptidase 14 (USP14), which is a deubiquitinating enzyme, and UCA1 functioned as a scaffold to recruit USP14 to profilin 1 (PFN1), an actin-binding protein contributing to endothelial abnormalities and vascular diseases. This ternary complex inhibited the ubiquitination-dependent degradation of PFN1 and prolonged its half-life, further activating the RhoA/Rho-kinase (ROCK) pathway to induce ROS production in endothelial cells. Taken together, these observations suggest a role for the evolution-related UCA1 in the HIF1α-induced adaptive pathogenic mechanism of preeclampsia, promoting the survival of hypoxic trophoblasts and injuring maternal endothelial cells.

Effect of the Recombinant Adenovirus-Mediated HIF-1 Alpha on the Expression of VEGF in the Hypoxic Brain Microvascular Endothelial Cells of Rats

OBJECTIVE

To investigate the effect of recombinant adenovirus-mediated HIF-1 alpha (HIF-1α) on the expression of vascular endothelial growth factor (VEGFA) and HIF-1α in hypoxic brain microvascular endothelial cells (BMEC) in rats.

METHODS

Primary cultured rat BMEC in vitro were treated without or with either recombinant adenovirus-mediated hypoxia-inducible factor-1 alpha (AdHIF-1α) or recombinant adenovirus empty vector (Ad) in the presence of CoCl₂ (simulating hypoxia conditions), or were grown under normoxia conditions. The expression of VEGFA and HIF-1α was analyzed at 12h, 24h, 48h and 72h incubation time, respectively. We also accessed a GEO dataset of stroke to analyze in vivo the alteration of HIF-1α and VEGFA expression, and the correlations between HIF-1α, VEGFA and CD31 mRNA levels in vascular vessels after stroke.

RESULTS

VEGFA and HIF-1α expression were significantly higher in at each time point in the AdHIF-1α than other groups (p<0.05), whereas the Ad group and hypoxia group, showed no statistically significant difference (p>0.05). Moreover, VEGFA and HIF-1α levels were significantly higher in BMEC under hypoxia conditions than normoxia conditions (p <0.05). Both HIF-1α and VEGFA expression significantly increased after stroke in vivo with 1.30 and 1.57 fold-change in log2, respectively. There were significantly positive associations between HIF-1α, VEGFA and CD31 mRNA levels in vivo after stroke.

CONCLUSION

Hypoxia-induced HIF-1α and VEGFA expression in vascular vessels, and recombinant AdHIF-1α could up-regulate VEGFA, and enhance HIF-1ααlevels in BMEC in vitro, which may play an important role in the recovery of stroke.

CXCR4 Antagonist AMD3100 Promotes Mesenchymal Stem Cell Mobilization in Rats Preconditioned with the Hypoxia-Mimicking Agent Cobalt Chloride

Mobilization of mesenchymal stem cells (MSCs) is an attractive strategy for cell therapy. Our previous study demonstrated that MSCs can be mobilized in circulating blood by short-term hypoxia, and hypoxia-inducible factor-1α is essential for MSC mobilization. In the present study, the effect of the hypoxia-mimicking agent CoCl₂ was examined on MSC mobilization. The results indicated that the frequency of circulating MSCs increased slightly by administration of CoCl₂. However, the mobilization efficiency was low. Considering the critical role of stromal cell-derived factor-1α (SDF-1)/CXCR4 axis in the regulation of MSC migration, the effects of granulocyte colony-stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100 were investigated on MSC mobilization. The experiments were notably demonstrated in animals preconditioned with CoCl₂. The frequency of colony-forming unit fibroblast and the proportion of CD45^-CD90⁺ cells did not significantly increase in the peripheral blood of rats treated with G-CSF and/or AMD3100 alone. The concomitant administration of G-CSF with CoCl₂ could not stimulate the release of MSCs. However, AMD3100 dramatically increased MSC mobilization efficiency in rats pretreated with CoCl_2. Furthermore, we identified and compared the multilineage differentiation capacities of MSCs derived from bone marrow (BM-MSCs) and mobilized peripheral blood (PB-MSCs). The results indicated that PB-MSCs exhibited higher osteogenic potential and lower adipogenic differentiation as compared with BM-MSCs. The findings may inform studies investigating mechanisms of the regulation of MSC mobilization and can aid in the development of clinically useful therapeutic agents.

The crosstalk between vascular MSCs and inflammatory mediators determines the pro-calcific remodelling of human atherosclerotic aneurysm

Background

Human mesenchymal stem cells (MSCs) possess well-known reparative abilities, but any defect of the immunomodulatory activity and/or the differentiation process may determine the development of human diseases, including those affecting the vascular wall. MSCs residing within the human aortic wall represent a potential cell mediator of atherosclerotic aneurysm development.

Methods

MSCs isolated from healthy and aneurysm aortas were characterized by flow cytometer and tested for differentiation properties. Healthy aorta (ha)-MSCs were then subjected to inflammatory stimuli to evaluate the microenvironmental impact on their function and involvement in vascular remodelling.

Results

Abdominal aortic aneurysm (AAA)-MSCs were isolated from calcified and inflamed aortas of 12 patients with high serum levels of MMP-9 protein. AAA-MSCs expressed typical mesenchymal markers and, in line with the histological analysis, elevated levels of OPN, an osteogenic marker also involved in vascular remodelling. AAA-MSCs were highly osteogenic and underwent intense calcium deposition under proper stimulation; moreover, AAA-MSCs were able to differentiate into tubule-like structures in Matrigel, even if the lack of CD146 and the reduced structural stability suggested an inefficient maturation process. We further demonstrated an association between osteogenesis and inflammation; indeed, ha-MSCs cultured with either cytokines (TNF-α, IL-1β) or AAA-PBMCs showed increased expression of MMP-9 and osteogenic markers, to the detriment of the adipogenic regulator PPAR-γ. Interestingly, the culture with inflammatory cells highly stimulated ha-MSCs towards the osteogenic commitment.

Conclusions

AAA-MSCs displayed high osteogenic potential and pathological angiogenesis that represent crucial steps for AAA progression; we showed that the inflammatory process critically addresses human vascular MSCs towards a pathological behaviour, inducing vascular bone matrix deposition and remodelling. Inhibition of this pathway may represent a pharmacological approach against arterial calcification.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0554-x) contains supplementary material, which is available to authorized users.

Mesenchymal stem cells in the aseptic loosening of total joint replacements

Peri-prosthetic osteolysis remains as the main long-term complication of total joint replacement surgery. Research over four decades has established implant wear as the main culprit for chronic inflammation in the peri-implant tissues and macrophages as the key cells mediating the host reaction to implant-derived wear particles. Wear debris activated macrophages secrete inflammatory mediators that stimulate bone resorbing osteoclasts; thus bone loss in the peri-implant tissues is increased. However, the balance of bone turnover is not only dictated by osteoclast-mediated bone resorption but also by the formation of new bone by osteoblasts; under physiological conditions these two processes are tightly coupled. Increasing interest has been placed on the effects of wear debris on the cells of the bone-forming lineage. These cells are derived primarily from multipotent mesenchymal stem cells (MSCs) residing in bone marrow and the walls of the microvasculature. Accumulating evidence indicates that wear debris significantly impairs MSC-to-osteoblast differentiation and subsequent bone formation. In this review, we summarize the current understanding of the effects of biomaterial implant wear debris on MSCs. Emerging treatment options to improve initial implant integration and treat developing osteolytic lesions by utilizing or targeting MSCs are also discussed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1195-1207, 2017.