BACKGROUNDPlatelet-rich plasma (PRP) as a storage vehicle of growth factors has been successfully used in clinical applications, but in most cases the platelets were autologous. However, the large volume of blood withdrawn has detrimental effects on patients with anemia or poor general health. To overcome these limitations, this study was designed to separate the growth factors in homologous platelet-rich plasma.

METHODSThe gel chromatography with Superdex-75 column was applied to separate PRP supernatants into 4 major fractions. Then the four fractions were vacuumed freeze-dried and re-dissolved in phosphate buffered saline. Proteins concentrations in PRP and in four fractions were detected by bicinchoninic acid protein assay; platelet derived growth factor-AB (PDGF-AB) and transforming growth factor beta1 (TGF-beta1) levels were determined by sandwich enzyme-linked immunosorbent assays. The effects of fractions on the proliferation of human marrow-derived mesenchymal stem cells (MSCs) were determined by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay.

RESULTSPRP supernatants were separated into four major fractions by gel chromatography. The proteins recovery was 96.72%. Of the four fractions, fraction B contained the highest TGF-beta1 and PDGF-AB levels, and the highest proteins concentrations. Cell proliferation curves of MSC demonstrated that fraction B and C induced a remarkable increase of MTT values compared to the untreated culture (P < 0.05), and the effects of fraction B and C showed no significant difference compared to the PRP group (P > 0.05). Fraction A and D showed no significant difference to the negative control group (P > 0.05).

CONCLUSIONSThe growth factors in PRP supernatants could be preliminarily separated into four fractions by gel chromatography, and the freeze-drying fractions retained the biological activity of growth factors. The growth factors were mostly presented in fraction B and C, and they promoted cell proliferation effectively.