Erythroid differentiation of human induced pluripotent stem cells is independent of donor cell type of origin

Epigenetic memory in induced pluripotent stem cells, which is related to the somatic cell type of origin of the stem cells, might lead to variations in the differentiation capacities of the pluripotent stem cells. In this context, induced pluripotent stem cells from human CD34(+) hematopoietic stem cells might be more suitable for hematopoietic differentiation than the commonly used fibroblast-derived induced pluripotent stem cells. To investigate the influence of an epigenetic memory on the ex vivo expansion of induced pluripotent stem cells into erythroid cells, we compared induced pluripotent stem cells from human neural stem cells and human cord blood-derived CD34(+) hematopoietic stem cells and evaluated their potential for differentiation into hematopoietic progenitor and mature red blood cells. Although genome-wide DNA methylation profiling at all promoter regions demonstrates that the epigenetic memory of induced pluripotent stem cells is influenced by the somatic cell type of origin of the stem cells, we found a similar hematopoietic induction potential and erythroid differentiation pattern of induced pluripotent stem cells of different somatic cell origin. All human induced pluripotent stem cell lines showed terminal maturation into normoblasts and enucleated reticulocytes, producing predominantly fetal hemoglobin. Differences were only observed in the growth rate of erythroid cells, which was slightly higher in the induced pluripotent stem cells derived from CD34(+) hematopoietic stem cells. More detailed methylation analysis of the hematopoietic and erythroid promoters identified similar CpG methylation levels in the induced pluripotent stem cell lines derived from CD34(+) cells and those derived from neural stem cells, which confirms their comparable erythroid differentiation potential.close1

Embolic Cerebral Insults After Transapical Aortic Valve Implantation Detected by Magnetic Resonance Imaging

ObjectivesThis study assessed the rate of periprocedural embolic ischemic brain injury during transapical aortic valve replacement in 25 consecutive patients.BackgroundTranscatheter aortic valve implantation is rapidly being established as a new therapeutic approach for aortic valve stenosis. Although initial clinical results are promising, it is unknown whether mobilization and embolization of calcified particles may lead to cerebral ischemia.MethodsTwenty-five consecutive patients (10 men, 15 women, mean age: 81 ± 5 years, mean log EuroSCORE [European System for Cardiac Operative Risk Evaluation]: 32 ± 10%) scheduled for transapical aortic valve implantation were included. All patients received a baseline cerebral magnetic resonance imaging scan. The scan was repeated approximately 6 days after valve implantation. The magnetic resonance imaging studies included axial diffusion–weighted, T2-weighted, fluid attenuated inversion recovery–weighted, and T2 gradient echo sequences. Standardized assessment of the neurologic status was performed before aortic valve replacement and post-operatively.ResultsTransapical aortic valve implantation was successfully performed in all patients. In 17 patients (68%), new cerebral lesions could be detected, whereas 8 patients showed no new cerebral insults. The pattern of distribution and morphology were typical of embolic origin. Despite the high incidence of morphologically detectable lesions, only 5 patients showed clinical neurologic alterations. Out of these patients, only 1 suffered from a permanent stroke.ConclusionsNew embolic ischemic cerebral insults are detected in 68% of patients after transapical valve implantation. Clinical symptoms are rare and usually transitory. Larger trials will need to establish the clinical significance of asymptomatic ischemic lesions as well as the rate of ischemic events in patients undergoing transfemoral valve replacement

Preferential inhibition of adaptive immune system dynamics by glucocorticoids in patients after acute surgical trauma

Glucocorticoids (GC) are commonly used to suppress undesirable inflammatory responses. Here the authors show, using hi-dimensional flow cytometry data, that GC treatment following major surgeries alters adaptive immunity without significant modulation of innate immune responses or pain/functional impairment

Author Correction: Preferential inhibition of adaptive immune system dynamics by glucocorticoids in patients after acute surgical trauma

An amendment to this paper has been published and can be accessed via a link at the top of the paper