Endothelial progenitor cell (EPC) nomenclature remains ambiguous and there is a general lack of concordance in the stem cell field with many distinct cell sub-types continually grouped under the term “EPC”. It would be highly advantageous to agree standards to confirm an endothelial progenitor phenotype and this should include detailed immunophenotyping, potency assays, and clear separation from haematopoietic angiogenic cells which are not endothelial progenitors. In this review, we seek to discourage the indiscriminate use of ‘EPCs’, and instead propose precise terminology based on defining cellular phenotype and function. Endothelial colony forming cells (ECFCs) and myeloid angiogenic cells (MACs) are examples of two distinct and well-defined cell types that have been considered ‘EPCs’ because they both promote vascular repair, albeit by completely different mechanisms of action. It is acknowledged that scientific nomenclature should be a dynamic process driven by technological and conceptual advances; ergo the ongoing ‘EPC’ nomenclature ought not to be permanent and should become more precise in the light of strong scientific evidence. This is especially important as these cells become recognised for their role in vascular repair in health and disease; and, in some cases, progress towards use in cell therapy.

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Most genetic susceptibility to cutaneous melanoma remains to be discovered. Meta-analysis genome-wide association study (GWAS) of 36,760 melanoma cases (67% newly-genotyped) and 375,188 controls identified 54 significant loci with 68 independent SNPs. Analysis of risk estimates across geographical regions and host factors suggests the acral melanoma subtype is uniquely unrelated to pigmentation. Combining this meta-analysis with nevus count and hair color GWAS, and transcriptome association approaches, uncovered 31 potential secondary loci, for a total of 85 cutaneous melanoma susceptibility loci. These findings provide substantial insights into cutaneous melanoma genetic architecture, reinforcing the importance of nevogenesis, pigmentation, and telomere maintenance together with identifying potential new pathways for cutaneous melanoma pathogenesis.

Context During pregnancy, fetal CD34 + cells enter the maternal circulation, persist for decades, and create a state of physiologic microchimerism. Many studies have confirmed the residual presence of fetal cells in maternal blood and tissues following pregnancy. Fetal cells may respond to maternal injury by developing multilineage capacity in maternal organs. Objective To verify that fetal microchimeric cells express markers of epithelial, leukocyte, and hepatocyte differentiation within maternal organs. Design, Setting, and Patients Archived paraffin-embedded tissue section specimens from 10 women who had male offspring and were previously found to have high numbers of microchimeric cells, and 11 control women who had no prior male pregnancies. Male cells were identified by fluorescence in situ hybridization, using X and Y chromosome-specific probes, followed by histologic and immunochemical studies using anticytokeratin (AE1/AE3) as a marker of epithelial cells, anti-CD45 as a leukocyte marker, and heppar-1 as a hepatocyte marker. Main Outcome Measure Percentage of microchimeric cells expressing nonhematopoietic markers. Results A total of 701 male (XY+) microchimeric cells were identified (mean [SD], 227 [128] XY+ cells per million maternal cells). In maternal epithelial tissues (thyroid, cervix, intestine, and gallbladder), 14% to 60% of XY+ cells expressed cytokeratin. Conversely, in hematopoietic tissues, such as lymph nodes and spleen, 90% of XY+ cells expressed CD45. In 1 liver sample, 4% of XY+ cells expressed heppar-1. Histologic and immunochemical evidence of differentiation, as assessed by independent observers, was highly concordant (=0.72). Conclusion The detection of microchimeric male cells, bearing epithelial, leukocyte, or hepatocyte markers, in a variety of maternal tissue specimens suggests the presence of fetal cells that may have multilineage capacity.

Our findings support an entirely novel endothelial hierarchy, from EVP to TA to D, as defined by self-renewal, differentiation, and molecular profiling of an endothelial progenitor. This paradigm shift in our understanding of vascular-resident endothelial progenitors in tissue regeneration opens new avenues for better understanding of cardiovascular biology.

Fetal cells circulate in pregnant women and persist in blood and tissue for decades post-partum. The mother thus becomes chimeric. Factors that may influence such fetal cell microchimerism include histocompatibility, fetal or placental abnormalities, or a reproductive history that includes miscarriage or elective termination. Fetal cell microchimerism is associated with some maternal autoimmune diseases, such as systemic sclerosis. Moreover, a novel population of fetal cells, the pregnancy-associated progenitor cells (PAPCs), appears to differentiate in diseased or injured maternal tissue. The cellular origin of these cells is at present unknown but could be a hematopoietic stem cell, a mesenchymal stem cell, or a novel cell type. Pregnancy therefore results in the acquisition of cells with stem-cell-like properties that may influence maternal health post-partum. Rather than triggering disease, these cells may instead combat it.

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Erythema nodosum and pyoderma gangrenosum are the most common cutaneous manifestations in inflammatory bowel diseases (IBD). We conducted the current study to assess the cumulative prevalence of erythema nodosum and pyoderma gangrenosum in patients with IBD and to appraise their association with demographic, clinical, and prognostic factors related to IBD. Between 2000 and 2005, data for all patients with IBD at our gastroenterology department were prospectively and systematically collected using a standardized protocol. Among 2402 patients (1521 diagnosed with Crohn disease [63.3%] and 744 with ulcerative colitis [31.0%]), 140 (5.8%) had at least 1 skin manifestation. The most frequent dermatologic symptoms were erythema nodosum (4.0%) and pyoderma gangrenosum (0.75%). In multivariate analyses, erythema nodosum was significantly and independently associated with a diagnosis of Crohn disease (p < 0.001), female sex (p < 0.001), eye and joint involvement (p < 0.001), and pyoderma gangrenosum (p < 0.0001). Among patients with Crohn disease, erythema nodosum was associated with isolated colonic involvement (p = 0.0001). Pyoderma gangrenosum was significantly and independently associated with black African origin (p = 0.003), familial history of ulcerative colitis (p = 0.0005), uninterrupted pancolitis as the initial location of IBD (p = 0.03), permanent stoma (p = 0.002), eye involvement (p = 0.001), and erythema nodosum (p < 0.0001). It is noteworthy that the association between pyoderma gangrenosum and permanent stoma persisted after exclusion of patients with peristomal pyoderma gangrenosum (p = 0.07). In conclusion, neither erythema nodosum nor pyoderma gangrenosum was significantly associated with the severity criteria in IBD; however, their occurrence may reflect a peculiar phenotype among affected patients.