Cell lineages and tissue boundaries in cardiac arterial and venous poles: developmental patterns, animal models, and implications for congenital vascular diseases

Transforming growth factor serum concentrations in patients with proven non-syndromic aortopathy

Background

The mechanism underlying aortic dilatation is still unknown. Vascular dilatation is thought to be the result of progressive aortic media degeneration caused by defective vascular matrix hemostasis, including TGF-β1 dysregulation. The goal of this study is to draw attention to the potential utility of TGF-β1 as a diagnostic marker in non-syndromic patients with aortic dilatation.

Methods

TGF-β1 levels in plasma were measured in 50 patients who had undergone surgery and had a tricuspid or bicuspid aortic valve as well as a normal or dilated ascending aorta. A pathologist also examined thirty resected aorta samples. To specify the reference range of TGF-β1, a control group of 40 volunteers was enrolled in this study.

Results

We discovered a significant difference in TGF-β1 levels between patients with aortic dilatation and the control group (32.5 vs. 63.92; P < 0.001), as well as between patients with non-dilated aorta but with aortic valve disease, and the control group (27.68 vs. 63.92; P < 0.001). There was no difference between the dilated ascending aorta group and the non-dilated ascending aorta group. We found a poor correlation between TGF-β1 levels and ascending aorta diameter as well as the grade of ascending aorta histopathological abnormalities.

Conclusion

TGF-β1 concentration does not meet the criteria to be a specific marker of aortic dilatation, but it is sensitive to aortic valvulopathy-aortopathy. A larger patient cohort study is needed to confirm these findings.

Pathogenesis of acute aortic dissection: a finite element stress analysis

BACKGROUND

Type A and type B aortic dissections typically result from intimal tears above the sinotubular junction and distal to the left subclavian artery (LSA) ostium, respectively. We hypothesized that this pathology results from elevated pressure-induced regional wall stress.

METHODS

We identified 47 individuals with normal thoracic aortas by electrocardiogram-gated computed tomography angiography. The thoracic aorta was segmented, reconstructed, and triangulated to create a geometric mesh. Finite element analysis using a systolic pressure load of 120 mm Hg was performed to predict regional thoracic aortic wall stress.

RESULTS

There were local maxima of wall stress above the sinotubular junction in the ascending aorta and distal to the ostia of the supraaortic vessels, including the LSA, in the aortic arch. No local maximum of wall stress was found in the descending thoracic aorta. Comparison of the mean peak wall stress above the sinotubular junction (0.43 ± 0.07 MPa), distal to the LSA (0.21 ± 0.07 MPa), and in the descending thoracic aorta (0.06 ± 0.01 MPa) showed a significant effect for wall stress by aortic region (p < 0.001).

CONCLUSIONS

In the normal thoracic aorta, there are peaks in wall stress above the sinotubular junction and distal to the LSA ostium. This stress distribution may contribute to the pathogenesis of aortic dissections, given their colocalization. Future investigations to determine the utility of image-derived biomechanical calculations in predicting aortic dissection are warranted, and therapies designed to reduce the pressure load-induced wall stress in the thoracic aorta are rational.

Differential availability/processing of decorin precursor in arterial and venous smooth muscle cells

The existence of specific differentiation markers for arterial smooth muscle (SM) cells is still a matter of debate. A clone named MM1 was isolated from a library of monoclonal antibodies to adult porcine aorta, which in vivo binds to arterial but not venous SM cells, except for the pulmonary vein. MM1 immunoreactivity in Western blotting involved bands in the range of M(r) 33-226 kDa, in both arterial and venous SM tissues. However, immunoprecipitation experiments revealed that MM1 bound to a 100-kDa polypeptide that was present only in the arterial SM extract. By mass spectrometry analysis of tryptic digests from MM1-positive 130- and 120-kDa polypeptides of aorta SM extract, the antigen recognized by the antibody was identified as a decorin precursor. Using a crude decorin preparation from this tissue MM1 reacted strongly with the 33-kDa polypeptide and this pattern did not change after chondroitinase ABC treatment. In vitro, decorin immunoreactivity was found in secreted grainy material produced by confluent arterial SM cells, although lesser amounts were also seen in venous SM cells. Western blotting of extracts from these cultures showed the presence of the 33-kDa band but not of the high-molecular-weight components, except for the 100-kDa monomer. The 100/33-kDa combination was more abundant in arterial SM cells than in the venous counterpart. In the early phase of neointima formation, induced by endothelial injury of the carotid artery or vein-to-artery transposition, the decorin precursor was not expressed, but it was up-regulated in the SM cells of the media underlying the neointima in both models. Collectively, these data suggest a different processing/utilization of the 100-kDa monomer of proteoglycan decorin in arterial and venous SM cells, which is abolished after vein injury.

How congenital heart disease originates in fetal life

Knowledge of the early development of the heart has increased rapidly in recent years as microscopic techniques, experimental models using animal, avian and insect species, and various genetic techniques have been brought to bear on the mysteries of human fetal cardiac development. The development of the heart occurs rapidly from embryonic day 18 in humans to the twelfth week of fetal life. The stages include gastrulation and formation of the primitive heart tube with rhythmic contractions appearing at day 21, segmentation of the primitive heart tube, looping, realignment of inflow and outflow segments, septation of the atria, ventricles and outflow segments, formation of atrio-ventricular valves, and development of aortic and pulmonary trunks and aortic arches. The genes and factors currently known to be involved in cardiac development are reviewed, but much is still to be determined as the field is evolving with extraordinary rapidity.