Cell-type-specific consequences of mosaic structural variants in hematopoietic stem and progenitor cells.

The functional impact and cellular context of mosaic structural variants (mSVs) in normal tissues is understudied. Utilizing Strand-seq, we sequenced 1,133 single-cell genomes from 19 human donors of increasing age, and discovered the heterogeneous mSV landscapes of hematopoietic stem and progenitor cells. While mSVs are continuously acquired throughout life, expanded subclones in our cohort are confined to individuals >60. Cells already harboring mSVs are more likely to acquire additional somatic structural variants, including megabase-scale segmental aneuploidies. Capitalizing on comprehensive single-cell micrococcal nuclease digestion with sequencing reference data, we conducted high-resolution cell-typing for eight hematopoietic stem and progenitor cells. Clonally expanded mSVs disrupt normal cellular function by dysregulating diverse cellular pathways, and enriching for myeloid progenitors. Our findings underscore the contribution of mSVs to the cellular and molecular phenotypes associated with the aging hematopoietic system, and establish a foundation for deciphering the molecular links between mSVs, aging and disease susceptibility in normal tissues.

Impact of aortic root geometry and degree of aortic calcification on outcomes of patients undergoing TAVI procedure.

AIMS: Adequate differentiation of calcifications in contrast-enhanced CT scans remains difficult to assess TAVI parameters. The size of the aortic leaflets has not been taken into account so far in present studies. The aim of our study was to establish a new method for optimized quantification of the aortic valve calcification degree in contrast-enhanced CT scans for better preoperative prediction of postoperative paravalvular leak after TAVI. METHODS AND RESULTS: We retrospectively analyzed preoperative contrast-enhanced CT scans of patients who underwent TAVI in our institution between 2014 and 2017. Calcium volume was quantified by a method using contrast enhanced computer tomography (3mensio-Structural Heart-7.2 software) with different iodine contents for better discrimination of contrast agent from calcium and by an individually set Houndsfield Unit (HU) threshold with 50HU above the individually determined reference value. Calcium volume was correlated with surface area of each aortic cusp. Perioperative variables were analyzed. All patients (n = 150) with severe aortic stenosis were treated with TAVI implantation. Overall incidence of postoperative trace to moderate PVL was 37%. The amount of calcium correlated with the incidence of PVL. In a logistic regression analysis total volume of calcification (p = .032) as well as calcification of each aortic cusp (NC_p = .001; RC_p < .001; LC_p = .001) were independent predictors. CONCLUSIONS: Calcification degree as well as its correlation with the surface area of each aortic cusp significantly influence incidence of PVL. Our new method improves preoperative quantification of the calcification degree by use of contrast agents with different iodine contents and thereby helps to improve patients' outcomes.

Aging of human hematopoietic stem cells is linked to changes in Cdc42 activity.

In this study, we characterize age-related phenotypes of human hematopoietic stem cells (HSC). We report increased frequencies of HSC, hematopoietic progenitor cells and lineage negative cells in the elderly but a decreased frequency of multi-lymphoid progenitors. Aged human HSC further exhibited a delay in initiating division ex vivo though without changes in their division kinetics. The activity of the small RhoGTPase Cdc42 was elevated in aged human hematopoietic cells and we identified a positive correlation between Cdc42 activity and the frequency of HSC upon aging. The frequency of human HSC polar for polarity proteins was, similar to the mouse, decreased upon aging, while inhibition of Cdc42 activity via the specific pharmacological inhibitor of Cdc42 activity, CASIN, resulted in re-polarization of aged human HSC with respect to Cdc42. Elevated activity of Cdc42 in aged HSC thus contributed to age-related changes in HSC. Xenotransplant, using NBSGW mice as recipients, showed elevated chimerism in recipients of aged compared to young HSC. Aged HSC treated with CASIN ex vivo displayed an engraftment profile similar to recipients of young HSC. Taken together, our work reveals strong evidence for a role of elevated Cdc42 activity in driving aging of human HSC, and similar to mice, this presents a likely possibility for attenuation of aging in human HSC.

First successful transcatheter double valve replacement from a transapical access and nine-month follow-up.

AIMS: While TAVI is the treatment of choice in patients with aortic stenosis considered inoperable or at high risk, interventional replacement of the mitral valve is still in the preclinical or early clinical phase. Our aim was to report on the first transcatheter double valve replacement into native valves from a transapical access. METHODS AND RESULTS: A 67-year-old, highly symptomatic female patient considered inoperable due to severe calcification of the mitral annulus and comorbidities was scheduled for transcatheter double valve replacement by the local Heart Team. Preoperative planning was carried out by multiplanar reconstruction from cardiac CT. Through a transapical access, the mitral valve was replaced first by an inverted 29 mm Edwards SAPIEN 3 prosthesis, then the aortic valve by a 23 mm SAPIEN 3, both during rapid pacing. Both prostheses revealed excellent function in angiography and echocardiography. The patient was extubated early after surgery and transferred to the normal ward the following day. After five months, she exhibited signs of cardiac failure again. Migration of the mitral prosthesis was detected, and the mitral valve was replaced surgically. CONCLUSIONS: Transcatheter double valve replacement can be performed through a transapical access. The key to success is thorough preoperative planning based on CT, not only for sizing, but also for estimating the anatomical relationship of the prostheses. However, late migration can be expected and may lead to LVOT obstruction.