Comparative Anti-Platelet Profiling Reveals a Potent Anti-Aggregatory Effect of CD34+ Progenitor Cell-Derived Late-Outgrowth Endothelial Cells in vitro.

BACKGROUND/AIMS: Platelets affect endothelial progenitor cell (EPC) functionality, inducing their differentiation into mature endothelial cells. However, it remains to be established whether EPCs can influence platelet functionality. METHODS: Mononuclear proangiogenic cells (MPCs) and early outgrowth cells (EOCs) were prepared from peripheral blood mononuclear cells, whereas late-outgrowth endothelial cells (OECs) were prepared from cord blood CD34+ cells. The effect of the above cells and their supernatants on washed platelet aggregation was studied. The effect of OECs and their supernatant on the adenosine diphosphate (ADP)-induced magnitude of platelet integrin receptor αIIbß3 activation and on P-selectin membrane expression was investigated. The levels of nitric oxide (NO) and prostacyclin (PGI2) that were secreted from EOCs, OECs, and human umbilical vein endothelial cells (HUVECs) were also assessed. RESULTS: Among all progenitors, OECs and their supernatant exhibited the most potent inhibitory activity towards platelet aggregation. Furthermore, OECs and their supernatant, but not CD34+ cells, reduced αIIbß3 activation and P-selectin membrane expression. Finally, OECs secreted higher NO and PGI2 levels than EOCs did. CONCLUSION: The anti-platelet effect of EPCs depends highly on the degree of their endothelial phenotype, with OECs expressing the highest potency. Therefore, the induction of OEC generation and the enhancement of their functionality in vivo could be a new approach for the treatment of patients at a high thrombotic risk.

The Effect of Platelet-Rich Plasma on Endothelial Progenitor Cell Functionality.

Platelets mediate circulating endothelial progenitor cell (EPC) recruitment and maturation, participating in vascular repair, however the underlying mechanism(s) remain unclear. We investigated the effect of platelet-rich plasma (PRP) on the functionality of CD34+-derived late-outgrowth endothelial cells (OECs) in culture. Confluent OECs were coincubated with PRP under platelet aggregation (with adenosine diphosphate; ADP) and nonaggregation conditions, in the presence/absence of the reversible P2Y12 platelet receptor antagonist ticagrelor. Outgrowth endothelial cell activation was evaluated by determining prostacyclin (PGI2) and monocyte chemoattractant protein-1 (MCP-1) release and intercellular adhesion molecule-1 (ICAM-1) membrane expression. Similar experiments were performed using human umbilical vein endothelial cells (HUVECs). Platelet-rich plasma increased ICAM-1 expression and PGI2 and MCP-1 secretion compared with autologous platelet-poor plasma, whereas ADP-aggregated platelets in PRP did not exhibit any effect. Platelet-rich plasma pretreated with ticagrelor prior to activation with ADP increased all markers to a similar extent as PRP. Similar results were obtained using HUVECs. In conclusion, PRP induces OEC activation, a phenomenon not observed when platelets are aggregated with ADP. Platelet inhibition with ticagrelor restores the PRP capability to activate OECs. Since EPC activation is important for endothelial regeneration and angiogenesis, we suggest that agents inhibiting platelet aggregation, such as ticagrelor, may promote platelet-EPC interaction and EPC function.

Alopecia associated with birth injury.

BACKGROUND: Alopecia after birth-related caput succedaneum is an extremely rare complication. CASE: The case of a child with permanent alopecia due to birth-related caput succedaneum is presented. After delivery with vacuum extraction, caput succedaneum at the left occipitoparietal region of the neonate's head was noted, which subsided within a week, leaving a circular necrotic crust and finally a circular bald area. At age 4, the child was referred at a tertiary center for the management of alopecia. Treatment initially consisted of the expansion of the hair-bearing skin adjacent to the bald area, which was excised at a second stage and covered with the expanded skin. A pleasing esthetic result was achieved. CONCLUSION: Neonatal alopecia is a rare birth-associated complication. Premature rupture of the membranes, prolonged second stage of the labor, and prolonged vacuum extraction time may be important features in the pathogenesis of this complication. In case of permanent alopecia, excellent esthetic results can be achieved with the use of reconstructive plastic surgery techniques.