Differences between Platelets Derived from Neonatal Cord Blood and Adult Peripheral Blood Assessed by Mass Spectrometry

It
has been proposed that differences may exist between umbilical cord
blood (CB) platelets and adult peripheral blood (APB) platelets, including
altered protein levels of the main platelet integrins. We have now
compared the protein expression profiles of CB and APB platelets employing
a label-free comparative proteomics approach. Aggregation studies
showed that CB platelets effectively aggregate in the presence of
thromboxane A2 analogue, collagen, and peptide agonists of the proteinase-activated
receptors 1 and 4. In agreement with previous studies, higher concentrations
of the agonists were required to initiate aggregation in the CB platelets.
Mass spectrometry analysis revealed no significant difference in the
expression levels of critical platelet receptors like glycoprotein
(GP)­Ib, GPV, GPIX, and integrin αIIbβ3. This was confirmed
using flow cytometry-based approaches. Gene ontology enrichment analysis
revealed that elevated proteins in CB platelets were in particular
enriched in proteins contributing to mitochondrial energy metabolism
processes. The reduced proteins were enriched in proteins involved
in, among others, platelet degranulation and activation. In conclusion,
this study reveals that the CB and APB platelets are distinct. In
particular, changes were observed for proteins that belong to metabolic
and energy generation processes and not for the critical adhesive
platelet integrins and glycoproteins.