Abstract
Background aims. The clinical use of human mesenchymal stromal cells (MSC) requires ex vivo expansion in media containing supplements such as fetal bovine serum or, alternatively, human platelet lysate (PL). Methods. Platelet concentrates were frozen, quarantine stored, thawed and sterile filtered to obtain PL. PL content and its effect on fibroblast–colony-forming unit (CFU-F) formation, MSC proliferation and large-scale expansion were studied. Results. PL contained high levels of basic fibroblast growth factor (bFGF), soluble CD40L (sCD40L), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-derived growth factor AA (PDGF-AA), platelet-derived growth factor AB/BB (PDGF-AB/BB), chemokine (C-C) ligand 5 (CCL5; RANTES) transforming growth factor-β1 (TGF-β1) and chemokine (C-X-C) ligand 1/2/3 (GRO), with low batch-to-batch variability, and most were stable for up to 14 days. Inhibition of PDGF-BB and bFGF decreased MSC proliferation by about 20% and 50%, respectively. The strongest inhibition (about 75%) was observed with a combination of anti-bFGF + anti-PDGF-BB and anti-bFGF + anti-TGF-β1 + anti-PDGF-BB. Interestingly, various combinations of recombinant PDGF-BB, bFGF and TGF-β1 were not sufficient to promote cell proliferation. PL from whole blood-derived pooled platelet concentrates and apheresis platelet concentrates did not differ significantly in their growth-promoting activity on MSC. Conclusions. PL enhances MSC proliferation and can be regarded as a safe tool for MSC expansion for clinical purposes. \in particular, PDGF-BB and bFGF are essential components for the growth-promoting effect of PL, but are not sufficient for MSC proliferation.
Acknowledgments
We appreciate the excellent technical assistance of G. Baur, T. Becker, S. Chester, D. Erz, K. Fuchs, S. Kluge, U. Schäfer and C. Späth. We are thankful for the possibility of obtaining BM from Dr Marx, University Freiburg, Germany.
This work was supported by a grant from the 7th Framework Program of the European Commission: CASCADE (Cultivated Adult Stem Cells as Alternative for Damaged Tissue) (number 223236; HEALTH-F5-2009–223236) and REBORNE (REgenerating BOne defects using New biomedical Engineering approaches) (number HEALTH-2009-1.4.2-241879).
Disclosure of interest: NF, DF, CM, JD, RL, HS and MTR are employed by a German transfusion service that produces and distributes platelet lysate. MG, SF-C, PB and LS are employed by a French Transfusion Service that produces platelet lysate. AI declares no conflict of interest.