Endothelial cell-derived pentraxin 3 limits the vasoreparative therapeutic potential of circulating angiogenic cells

Abstract

AimsCirculating angiogenic cells (CACs) promote revascularization of ischaemic tissues although their underlying mechanism of action and the consequences of delivering varying number of these cells for therapy remain unknown. This study investigates molecular mechanisms underpinning CAC modulation of blood vessel formation.Methods and resultsCACs at low (2 × 105 cells/mL) and mid (2 × 106 cells/mL) cellular densities significantly enhanced endothelial cell tube formation in vitro, while high density (HD) CACs (2 × 107 cells/mL) significantly inhibited this angiogenic process. In vivo, Matrigel-based angiogenesis assays confirmed mid-density CACs as pro-angiogenic and HD CACs as anti-angiogenic. Secretome characterization of CAC-EC conditioned media identified pentraxin 3 (PTX3) as only present in the HD CAC-EC co-culture. Recombinant PTX3 inhibited endothelial tube formation in vitro and in vivo. Importantly, our data revealed that the anti-angiogenic effect observed in HD CAC-EC co-cultures was significantly abrogated when PTX3 bioactivity was blocked using neutralizing antibodies or PTX3 siRNA in endothelial cells. We show evidence for an endothelial source of PTX3, triggered by exposure to HD CACs. In addition, we confirmed that PTX3 inhibits fibroblast growth factor (FGF) 2-mediated angiogenesis, and that the PTX3 N-terminus, containing the FGF-binding site, is responsible for such anti-angiogenic effects.ConclusionEndothelium, when exposed to HD CACs, releases PTX3 which markedly impairs the vascular regenerative response in an autocrine manner. Therefore, CAC density and accompanying release of angiocrine PTX3 are critical considerations when using these cells as a cell therapy for ischaemic disease.

MSC-derived cytokines repair radiation-induced intra-villi microvascular injury

“…They found that under the same condition, VEGF concentrations were altered in the medium conditioned by MSCs from different donors, indicating different capabilities of MSCs in producing growth factors [ 19 ]. In addition, the present results also showed that pentraxin 3, which was capable of inhibiting tube formation of ECs [ 20 ], was also present in MSC-CM. Nevertheless, we still observed that HUVEC formed networks as soon as 4 hours after intervention by MSC-CM, implying that angiogenic factors of MSC-CM might contribute together to HUVEC branching in vitro .…”

The Vasoreparative Function of Myeloid Angiogenic Cells Is Impaired in Diabetes Through the Induction of IL1β

“…We have shown previously that MACs promote angiogenesis in mature endothelial cells through secretion of paracrine factors . Here, we have used ECFCs, as a recognized subtype of endothelial progenitors , because they are an ideal human endothelial test bed for investigating angiogenic responses with enhanced sensitivity.…”

“…Preliminary results have shown cytotherapy to be safe, tolerable, and feasible although clinical efficacy has been inconsistent . Myeloid angiogenic cells (MACs), isolated from the mononuclear cell (MNC) fraction of human peripheral blood, are also known as circulating angiogenic cells (CACs) and we have previously characterized them in detail . MACs have shown promising results in preclinical models for critical limb ischemia , acute myocardial infarction , and pulmonary arterial hypertension .…”

Vascular Regeneration for Ischemic Retinopathies: Hope from Cell Therapies

“…The immunophenotype of MACs is positive for CD45, CD14 and CD31, while negative for CD146. 42,70 In culture, MACs do not have significant proliferative capacity, and are known to promote angiogenesis through paracrine mechanisms. 70 Transcriptome and proteomic analysis have revealed that MACs, unlike ECFCs, are myeloid in origin and express markers of M2 activated macrophages.…”

“…42,70 In culture, MACs do not have significant proliferative capacity, and are known to promote angiogenesis through paracrine mechanisms. 70 Transcriptome and proteomic analysis have revealed that MACs, unlike ECFCs, are myeloid in origin and express markers of M2 activated macrophages. 71 In the murine model of hind-limb ischemia, infusion of CD14 + MNC-derived EPCs (akin to MACs) induced neovascularization of ischemic muscle within 24 h. 72 The emerging promise has led to trials investigating the therapeutic efficacy of autologous MAC-like cells for treating ischemic pathologies in patients with critical limb ischemia 73 , myocardial infarction 74 and pulmonary arterial hypertension.…”