Human Aortic Valve Interstitial Cells Display Proangiogenic Properties During Calcific Aortic Valve Disease

OBJECTIVE

The study's aim was to analyze the capacity of human valve interstitial cells (VICs) to participate in aortic valve angiogenesis. Approach and Results: VICs were isolated from human aortic valves obtained after surgery for calcific aortic valve disease and from normal aortic valves unsuitable for grafting (control VICs). We examined VIC in vitro and in vivo potential to differentiate in endothelial and perivascular lineages. VIC paracrine effect was also examined on human endothelial colony-forming cells. A pathological VIC (VICp) mesenchymal-like phenotype was confirmed by CD90+/CD73+/CD44+ expression and multipotent-like differentiation ability. When VICp were cocultured with endothelial colony-forming cells, they formed microvessels by differentiating into perivascular cells both in vivo and in vitro. VICp and control VIC conditioned media were compared using serial ELISA regarding quantification of endothelial and angiogenic factors. Higher expression of VEGF (vascular endothelial growth factor)-A was observed at the protein level in VICp-conditioned media and confirmed at the mRNA level in VICp compared with control VIC. Conditioned media from VICp induced in vitro a significant increase in endothelial colony-forming cell proliferation, migration, and sprouting compared with conditioned media from control VIC. These effects were inhibited by blocking VEGF-A with blocking antibody or siRNA approach, confirming VICp involvement in angiogenesis by a VEGF-A dependent mechanism.

CONCLUSIONS

We provide here the first proof of an angiogenic potential of human VICs isolated from patients with calcific aortic valve disease. These results point to a novel function of VICp in valve vascularization during calcific aortic valve disease, with a perivascular differentiation ability and a VEGF-A paracrine effect. Targeting perivascular differentiation and VEGF-A to slow calcific aortic valve disease progression warrants further investigation.

Management specificities for abdominal, pelvic and vascular penetrating trauma

Management of patients with penetrating trauma of the abdomen, pelvis and their surrounding compartments as well as vascular injuries depends on the patient's hemodynamic status. Multiple associated lesions are the rule. Their severity is directly correlated with initial bleeding, the risk of secondary sepsis, and lastly to sequelae. In patients who are hemodynamically unstable, the goal of management is to rapidly obtain hemostasis. This mandates initial laparotomy for abdominal wounds, extra-peritoneal packing (EPP) and resuscitative endovascular balloon occlusion of the aorta (REBOA) in the emergency room for pelvic wounds, insertion of temporary vascular shunts (TVS) for proximal limb injuries, ligation for distal vascular injuries, and control of exteriorized extremity bleeding with a tourniquet, compressive or hemostatic dressings for bleeding at the junction or borderline between two compartments, as appropriate. Once hemodynamic stability is achieved, preoperative imaging allow more precise diagnosis, particularly for retroperitoneal or thoraco-abdominal injuries that are difficult to explore surgically. The surgical incisions need to be large, in principle, and enlarged as needed, allowing application of damage control principles.

Variation of daily warm season mortality as a function of micro-urban heat islands

Background:

Little attention has been paid to how heat-related health effects vary with the micro-urban variation of outdoor temperatures. This study explored whether people located in micro-urban heat islands are at higher risk of mortality during hot summer days.

Methods:

Data used included (1) daily mortality for Montreal (Canada) for June–August 1990–2003, (2) daily mean ambient outdoor temperatures at the local international airport and (3) two thermal surface images (Landsat satellites, infrared wavelengths). A city-wide temperature versus daily mortality function was established on the basis of a case-crossover design; this function was stratified according to the surface temperature at decedents’ place of death.

Results:

The risk of death on warm summer days in areas with higher surface temperatures was greater than in areas with lower surface temperatures.

Conclusions:

This study suggests that measures aimed at reducing the temperature in micro-urban heat islands (eg, urban greening activities) may reduce the health impact of hot temperatures. Further studies are needed to document the variation of heat-related risks within cities and to evaluate the health benefits of measures aimed at reducing the temperature in micro-urban heat islands.