Influence of identified proteins and ATP on MSC proliferation. (A-C) MSC were seeded in 5% pHPL, tPRP and FBS, respectively, and stimulated for 3 days with: (A) 125, 250 and 500 μg/ml fibrinogen, (B) 20, 40 and 80 μg/ml apoA1 and (C) 45, 90, 180, and 106 nM ATP. Cell counts were measured using the CellTiter-Glo assay and then normalized to the unstimulated control to calculate relative cell count values. Symbols indicate statistically significant diffences between: * stimulation; + supplements; # MSC sources; (one symbol p < 0.05; two symbols p < 0.01). (D) Western blot verification of differentially expressed proteins, fibrinogen and apo-A1 in pHPL and tPRP (2.5 μg protein/lane, eight different batches, respectively). Functional platelet interaction network analysis for fibinogen gamma (E) and apolipoprotein A1 (F) was performed using PlateletWeb and subnet extraction according to Boyanova et al.  (white circles denote platelet proteins with no detected phosphorylation sites; black circles denote platelet proteins with phosphorylation sites detected in platelets; grey circles denote platelet proteins with phosphorylation sites detected in human cells).