PLATELET-ENRICHED PLASMA (PRP) AND CYTOSKELETON REARRANGEMENT IN HUMAN OSTEOBLASTS

Aim: The use of platelet-enriched plasma (PRP) has been proposed as a source of growth factors in enhancing new bone formation after fractures. However, the molecular mechanism at the basis of PRP action in tissue regeneration is not fully understood yet. The recent finding that PRP is a potent chemoattractive agent of osteoblasts “in vitro” (Celotti at al. 2006), prompted us to investigate whether the increased cell migration might be due to cytoskeleton rearrangements. Methods: Human osteoblastic cells (SaOS-2), grown to semiconfluence, were pre-treated with different PRP dilutions (1/1000 or 1/100) for different times (30, 60 or 150 minutes). The microchemotaxis assay was performed in Boyden chamber using FCS1% as chemotactic stimulus. The migrated cells were counted under optical microscope; F-actin was labelled with FITC-phalloidin and examined under laser confocal microscope. Results: PRP pre-treatment stimulates cell migration both in absence (DMEM) and in presence of FCS 1% in a dose- and time-dependent manner. Interestingly, PRP pre-treatment induces cytoskeleton reorganization of the actin microfilaments, promoting the formation of F-actin bundles. The extent of the rearrangement is dependent on the concentration and the lenght of the pre-treatment: PRP 1/100 is more effective in early F-actin organization (60 min.), while PRP 1/1000 needs a longer time to have the same effect. Conclusions: The pre-treatment with PRP is able to increase the migratory and chemokinesis capacity of osteoblastic cells by cytoskeleton reorganization. The molecular pathway linking PRP to actin microfilaments rearrangement is under investigation.