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The circulating endothelial progenitor cells (EPCs) in blood of acute myocardial infarction (AMI) patient have been monitored in many previous studies. The number of circulating EPC increases in the blood of patients at onset of the AMI. EPC is originated from bone marrow. It performs vessel regeneration. There are many markers used for detecting EPC. Four of these markers, CD31, CD34, CD45, and CD146, were concurrently detected at the single cell level for the identification of EPC in the present preliminary study. The CD45 negative cell sorting was performed to peripheral blood mononuclear cells (PBMCs) acquired from four AMI patients with a magnetic bead sorter, since, EPCs expressed CD45 negative or dim. The resultant PBMC eluents were treated with quantum-antibody conjugates for the probing four different markers of EPCs and then applied to a high-content single cell imaging cytometer using acousto-optical tunable filter (AOTF). The use of quantum dot, with narrow emission wavelength range and AOTF enabling cellular image at a particular single wavelength, is very advantageous for accurate high-content AMI diagnosis based on simultaneous monitoring of many markers. The number of EPC increased as compared with control in three of four AMI patients. In this approach, two EPC subtypes were found, CD31(+), CD34(+), CD45(-/dim), CD146(-) as early outgrowth EPCs and CD31(+), CD34(+), CD45(-/dim), CD146(+) as late outgrowth EPCs. Patient 1 had CD31(+), CD34(+), CD45(-/dim), CD146(+) cells whose percentage was 4.21% of cells. Patient 2 had 2.38% of CD31(+), CD34(+), CD45(-/dim), CD146(-) cells and patient 3 had 4.28% of CD31(+), CD34(+), CD45(-/dim), CD146(+) cells., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In vitro expanded bone marrow stromal cells contain at least two populations of fibroblasts, a CD146/MCAM positive population, previously reported to be critical for establishing the stem cell niche and a CD146-negative population that expresses CUB domain-containing protein 1 (CDCP1)/CD318. Immunohistochemistry of marrow biopsies shows that clusters of CDCP1+ cells are present in discrete areas distinct from areas of fibroblasts expressing CD146. Using a stromal cell line, HS5, which approximates primary CDCP1+ stromal cells, we show that binding of an activating antibody against CDCP1 results in tyrosine-phosphorylation of CDCP1, paralleled by phosphorylation of Src Family Kinases (SFKs) Protein Kinase C delta (PKC-δ). When CDCP1 expression is knocked-down by siRNA, the expression and secretion of myelopoietic cytokines is increased. These data suggest CDCP1 expression can be used to identify a subset of marrow fibroblasts functionally distinct from CD146+ fibroblasts. Furthermore the CDCP1 protein may contribute to the defining function of these cells by regulating cytokine expression.

The in vivo identity of stem cells is not yet clear. Numerous studies involve the perivascular niches as providers of stem cells during regenerative processes. CD146, in humans, as well as gicerin, at chicken, play roles in neuronal development and neurites extension. CD146 is a marker of stemness but also a pericytary marker. Stem cells in vascular niches can differentiate in neural cells. By applying CD146 and CD105 antibodies on human retinas from glaucomatous eyes, CD146-positive retinal ganglion cells (RGCs) were found, some being placed in perivascular positions; ongoing processes of neurites extension were related to these neurons. On other hand, RGCs were positively labeled by CD105 antibodies. These results support the hypothesis that in glaucoma eyes the CD146-positive RGCs result from regenerative processes driven by stem cells in the retinal perivascular niches. Further experiments are needed to evaluate whether CR146-positive neurons indicate also a physiological process of maintenance of retina., (Copyright © 2014 Elsevier Ltd. All rights reserved.)