Evaluation of Endothelial Progenitor Cell Characteristics as Clinical Biomarkers for Elderly Patients with Ischaemic Stroke

Abstract

Ageing impairs endothelial function and predisposes the person to ischaemic stroke (IS). Endothelial progenitor cells (EPCs) repair endothelial damage and induce post-ischaemic neovascularisation. Given the prevalence of IS in older population, this study explored whether changes in EPC number and function may reliably predict the type or outcome of stroke in patients ≥ 65 years of age. For this, blood samples were collected once from healthy volunteers (HVs, n = 40) and four times (admission and days 7, 30 and 90 post-stroke) from participants with lacunar (n = 38) or cortical (n = 43) stroke. EPCs were counted with flow cytometry and defined as non-haematopoietic cells (CD45-) expressing markers for stemness (CD34 +), immaturity (CD133 +) and endothelial maturity (KDR +). Clonogenesis, tubulogenesis, migration and proliferation assays were performed as measures of EPC functionality. Biochemical profile of plasma inflammatory and angiogenic agents were studied using specific ELISAs. Primary outcome was disability or dependence on day 90 post-stroke, assessed by the modified Rankin Scale (mRS). Compared to HVs, EPC numbers were higher in stroke patients at all time points studied, reaching significance at baseline and day 30. No differences in EPC counts and functionality were observed between lacunar and cortical stroke groups at any time. Plasma endostatin, PDGF-BB, TNF-α and VEGF levels were higher in stroke patients vs HVs. Patient outcome, evaluated by mRS on day 90 post-stroke, did not correlate with EPC count or functionality. Baseline EPC counts may serve as a diagnostic marker for stroke but fail to distinguish between different stroke subtypes and predict post-stroke outcome. Graphical Abstract

Immunological Profile and Markers of Endothelial Dysfunction in Elderly Patients with Cognitive Impairments

“…On the other hand, in a study by Rakkar et al, EPC numbers were higher in stroke patients at all-time points studied, reaching significance at baseline and day 30 [48]. Moreover, they came to the conclusion that baseline EPC counts may serve as a diagnostic marker for stroke but fail to distinguish between different stroke subtypes and predict post-stroke outcomes [48]. We revealed no significant deviations in EPC levels in the AIS group, which may be due to the age-related characteristics of our patients, the level of vascular damage, or the time period after the event, but most likely due to a combination of all these reasons.…”

“…Depletion of CD34+ and KDR+ EPCs is an independent predictor of early subclinical atherosclerosis in healthy subjects and may provide additional information beyond the classic risk factors and inflammatory markers [62]. On the other hand, in a study by Rakkar et al, EPC numbers were higher in stroke patients at all-time points studied, reaching significance at baseline and day 30 [48]. Moreover, they came to the conclusion that baseline EPC counts may serve as a diagnostic marker for stroke but fail to distinguish between different stroke subtypes and predict post-stroke outcomes [48].…”

“…MSCs are defined by the expression of CD105, CD73, and CD90 [46]. EMPs are usually evaluated as CD146 + and CD31+ cells, while EPCs can be evaluated as CD34 + and CD133+, CD34 + and VEGFR2+ cells, or CFU-En colony-forming units [47,48]. EPCs are defined as non-hematopoietic cells (CD45-) expressing markers for stemness (CD34+), immaturity (CD133+), and endothelial maturity (KDR+) [48].…”

“…EMPs are usually evaluated as CD146 + and CD31+ cells, while EPCs can be evaluated as CD34 + and CD133+, CD34 + and VEGFR2+ cells, or CFU-En colony-forming units [47,48]. EPCs are defined as non-hematopoietic cells (CD45-) expressing markers for stemness (CD34+), immaturity (CD133+), and endothelial maturity (KDR+) [48]. In the absence of hematopoietic (CD45 and CD14) and progenitor markers (CD34 and CD133), circulating EMPs can be identified as the cells expressing the endothelial markers CD146, CD144, VWF, and VEGFR2 [49].…”

Analysis of endothelial progenitor cell subtypes as clinical biomarkers for elderly patients with ischaemic stroke

“…Substantial decreases reported in the number of circulating EPCs expressing markers specifically for stemness and immaturity in healthy individuals over 65 years of age versus those between 18 and 64 years confirm the influence of ageing on distinct EPC subtypes 10 . In light of these and further findings implying the value of circulating EPCs for endothelial repair 6 , 11 , 17 and as potential prognostic biomarkers 18 , the present study hypothesised that changes in circulating numbers of certain EPC subtypes, defined as cells co-expressing a variety of markers for stemness (CD34 +), immaturity (CD133 +) and endothelial cell maturity (KDR +), may explain the differences reported in the severity and/or outcome of ischaemic stroke in older patients. Observation of a significant correlation in the current study between higher CD34 + KDR + and CD133 + KDR + numbers during the acute phase of stroke and better neurological and functional outcome on D90 post-stroke corroborate this hypothesis and attribute a key role to these particular EPC subtypes in neurovascular repair 19 , 20 .…”