The Number of Platelets in Patient's Blood Influences the Mechanical and Morphological Properties of PRP-Clot and Lysophosphatidic Acid Quantity in PRP.

Michela Bosetti,Massimiliano Leigheb,Massimiliano Leigheb,Mattia Colli,Matteo Brucoli,Alice Marchetti,Paolo Boffano

doi:10.3390/ijms21010139

Abstract

The objectives of this study were to compare platelet-rich plasma (PRP) from patients with different concentrations of platelets and to assess the influence of these PRP preparations on human osteoblast (hOB) activity. In the literature, growth factors released by activated platelets have been considered responsible for the active role of PRP on bone regeneration but no specific role has been attributed to lysophosphatidic acid (LPA) as a possible effector of biological responses. In this study, patients were grouped into either group A (poor in platelets) or group B (rich in platelets). Clots from PRP fraction 2 (F2-clots), obtained with CaCl2 activation of PRP from the two groups, were compared macroscopically and microscopically and for their mechanical properties before testing their activity on the proliferation and migration of hOB. LPA was quantified before and after PRP fractioning and activation. The fibrin network of F2-clots from patients with a lower platelet concentration had an organized structure with large and distinct fibers while F2-clots from patients in group B revealed a similar structure to those in group A but with a slight increase in density. ELISA results showed a significantly higher plasma level of LPA in patients with a higher platelet concentration (group B) in comparison to those in group A (p < 0.05). This different concentration was evidenced in PRP but not in the clots. Depending on the number of platelets in patient’s blood, a PRP-clot with higher or lower mechanical properties can be obtained. The higher level of LPA in PRP from patients richer in platelets should be considered as responsible for the higher hOB activity in bone regeneration.

Highlights

In the field of regenerative medicine and tissue engineering, there is great interest in the search for new compounds to be used as fillers and as promoters of tissue regeneration
We demonstrated that lysophosphatidic acid (LPA) confers osteoconductive properties to scaffold materials and that it fastens bone fragments through actin cytoskeleton reorganization and myosin light chain phosphorylation of human primary osteoblasts [17]
Few differences were found in the consistency and macroscopic structure of clots obtained by Platelet-rich plasma (PRP)-F2 coagulation with calcium chloride using PRP from patients of group A and patients of group B (Figure 1A,B)

Summary

Introduction

In the field of regenerative medicine and tissue engineering, there is great interest in the search for new compounds to be used as fillers and as promoters of tissue regeneration. The use of platelet concentrates in combination with natural and synthetic biomaterials has been widely assessed and examined, with the aim of obtaining a faster and better bone healing [1]. Platelet-rich plasma (PRP) is a widely used biomaterial for bone tissue regeneration, both as a three-dimensional scaffold with filling function and as a pharmacologically active compound capable of stimulating cell migration and cell proliferation at the site of the lesion [2,3,4]. Dental pulp tissue represents a source of mesenchymal stem cells that have a strong differentiation potential towards the osteogenic lineage and decellularized bone extracellular matrix might be considered as suitable scaffolds to support osteogenic differentiation of dental pulp stem cells [5]. Novel strategies to replace bone tissue can be considered too. Kerativitayanan et al reported synthesis and fabrication of porous and elastomeric nanocomposite scaffolds from biodegradable poly (glycerol sebacate) (PGS) and osteoinductive nanosilicates [6]

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