Leukocyte presence does not increase microbicidal activity of Platelet-rich Plasma in vitro

Abstract

BackgroundHuman platelets are a rich reservoir of molecules that promote regenerative processes and microbicidal activity. This activity might be increased by concentration in platelet-rich plasma (PRP) products and modulated by the presence of leukocytes. Despite extensive use in clinical procedures, only few studies have investigated PRP’s real microbicidal potential. Therefore, this study aimed at comparing the in vitro microbicidal activity of platelets and leukocyte-enriched PRP (L-PRP) to pure platelet-rich plasma (P-PRP) and the contribution of leukocytes to microbicidal properties.Antimicrobial effects of P- and L-PRP were tested against Escherichia Coli, Staphylococcus Aureus, Klebsiella Pneumoniae, Pseudomonas Aeruginosa and Enterococcus Faecalis. Furthermore, L-PRP was frozen (L-PRP cryo) to assess whether the preparation maintained in vitro characteristics. Microbicidal proteins released by the three preparations were also evaluated.ResultsL-PRP, L-PRP cryo and P-PRP generally induced comparable bacterial growth inhibition for up to 4 h’ incubation, range 1–4 log. MIP-1α, RANTES, GRO-α, IL-8, NAP-2, SDF-1α and IL-6 showed strong microbicidal potential.ConclusionsWe found in vitro antibacterial activity of L-PRP and P-PRP and the possibility to cryopreserve L-PRP, without important changes to its effectiveness; similar microbicidal activity between preparations containing or not leukocytes; and the contribution of three new molecules (NAP-2, SDF-1α and IL-6).

Leukocyte depletion does not affect the in�vitro healing ability of platelet rich plasma

“…It is still a subject of debate whether leukocytes have a positive or negative effect on healing processes (15). They may have beneficial effects because they stimulate the immune response against infections (19), but it has been recently demonstrated that L-PRP and P-PRP generally inhibit bacterial growth in a comparable way (20); leukocytes also increase GF release, contributing to angiogenesis, matrix production and hypercellularity (21). On the other hand, leukocytes may release inflammatory cytokines (such as TNF-α and reactive oxygen species) that may increase inflammation, having a detrimental effect by delaying tissue healing (17,22).…”

Platelet-Rich Plasma for the Treatment of Tissue Infection: Preparation and Clinical Evaluation

“…71 However, Mariani et al reported that leukocytes did not enhance the microbicidal activity of PRP in vitro, when L-PRP and pure PRP (P-PRP) were compared. 72 They concluded that the similar in vitro antibacterial activity of L-PRP and P-PRP may result from antimicrobial peptide release from both formulations, such as neutrophil-activating protein-2.…”

Platelets and Infections

“…[10] Known facts and quality of evidence Despite the role of leucocytes in invalidating the bacterial growth, the fact that the myeloper-oxidate concentration was similar in products with and without leucocytes indicates the antibacterial role of platelets. [11] Nevertheless, bacterial growth inhibition is determined by the quality of PRP. Variables that influence the quality and quantity of PRP are: the number of donor's platelets, the type of activating and clotting agent, the number of centrifugation steps, the force of gravity, the validation of method with positive results from clinical trials.…”