Assessment of Differentiation States of Hematopoietic Stem Cells Following in Vitro Culture Using Side and Forward Scatter of Flow Cytometry

Hematopoietic stem cells (HSC) are defined by the International Society of Hematotherapy and Graft Engineering (ISHAGE) as those at low side scatter, positive for CD34 and CD45dim for their numeration with flow cytometry. However, we found that these CD34+ cells increase their granularity and size following in vitro culture, which was exhibited in flow cytometry as more events at higher side scatter and forward scatter. To further determine whether such a change in the cell event distribution is related to HSC differentiation, HSC markers and differentiation markers of in vitro-cultured HSC were detected by flow cytometry at different side scatter and forward scatter levels using modified ISHAGE gating strategies.nbsp The results revealed that cultured HSC with higher side scatter have a lower percentage of cells positive for HSC markers and a higher percentage of differentiation makers, while those with higher forward scatter have a higher percentage of differentiation makers but a slightly higher percentage of stem cell markers, suggesting that side scatter and forward scatter levels of cultured HSC correlate with the differentiation level of these cells

Diastolic Ventricular Interaction in Heart Failure With Preserved Ejection Fraction

Background Exercise‐induced pulmonary hypertension is common in heart failure with preserved ejection fraction (HFpEF). We hypothesized that this could result in pericardial constraint and diastolic ventricular interaction in some patients during exercise. Methods and Results Contrast stress echocardiography was performed in 30 HFpEF patients, 17 hypertensive controls, and 17 normotensive controls (healthy). Cardiac volumes, and normalized radius of curvature (NRC) of the interventricular septum at end‐diastole and end‐systole, were measured at rest and peak‐exercise, and compared between the groups. The septum was circular at rest in all 3 groups at end‐diastole. At peak‐exercise, end‐systolic NRC increased to 1.47±0.05 (P<0.001) in HFpEF patients, confirming development of pulmonary hypertension. End‐diastolic NRC also increased to 1.54±0.07 (P<0.001) in HFpEF patients, indicating septal flattening, and this correlated significantly with end‐systolic NRC (ρ=0.51, P=0.007). In hypertensive controls and healthy controls, peak‐exercise end‐systolic NRC increased, but this was significantly less than observed in HFpEF patients (HFpEF, P=0.02 versus hypertensive controls; P<0.001 versus healthy). There were also small, non‐significant increases in end‐diastolic NRC in both groups (hypertensive controls, +0.17±0.05, P=0.38; healthy, +0.06±0.03, P=0.93). In HFpEF patients, peak‐exercise end‐diastolic NRC also negatively correlated (r=−0.40, P<0.05) with the change in left ventricular end‐diastolic volume with exercise (ie, the Frank‐Starling mechanism), and a trend was noted towards a negative correlation with change in stroke volume (r=−0.36, P=0.08). Conclusions Exercise pulmonary hypertension causes substantial diastolic ventricular interaction on exercise in some patients with HFpEF, and this restriction to left ventricular filling by the right ventricle exacerbates the pre‐existing impaired Frank‐Starling response in these patients