title: Leukocyte presence does not increase microbicidal activity of Platelet-rich Plasma in vitro.
abstract: BACKGROUND
  Human 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.
  
  
  RESULTS
  L-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.
  
  
  CONCLUSIONS
  We 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).
authors.affiliation: Laboratory of Immunorheumatology and Tissue Regeneration/RAMSES, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136, Bologna, Italy. erminia.mariani@unibo.it.|Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy. erminia.mariani@unibo.it.
authors.forename: Erminia
authors.initials: E
authors.lastname: Mariani
authors.affiliation: Laboratory of Immunorheumatology and Tissue Regeneration/RAMSES, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136, Bologna, Italy. valentina.canella@ior.it.
authors.forename: Valentina
authors.initials: V
authors.lastname: Canella
authors.affiliation: Unit of Clinical Microbiology, St. Orsola University Hospital, University of Bologna, Bologna, Italy. berli.a@libero.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Berlingeri
authors.affiliation: Unit of Clinical Microbiology, St. Orsola University Hospital, University of Bologna, Bologna, Italy. alessandra.bielli@gmail.com.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bielli
authors.affiliation: Laboratory of Immunorheumatology and Tissue Regeneration/RAMSES, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136, Bologna, Italy. luca.cattini@ior.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Cattini
authors.affiliation: Unit of Clinical Microbiology, St. Orsola University Hospital, University of Bologna, Bologna, Italy. mariapaola.landini@unibo.it.
authors.forename: Maria Paola
authors.initials: MP
authors.lastname: Landini
authors.affiliation: Laboratory of Biomechanics and Technology Innovation/NABI, 2nd Orthopaedic and Traumatologic Clinic, Rizzoli Orthopaedic Institute, via di Barbiano 1/10, Bologna, Italy. e.kon@biomec.ior.it.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Kon
authors.affiliation: Laboratory of Biomechanics and Technology Innovation/NABI, 2nd Orthopaedic and Traumatologic Clinic, Rizzoli Orthopaedic Institute, via di Barbiano 1/10, Bologna, Italy. m.marcacci@biomec.ior.it.
authors.forename: Maurilio
authors.initials: M
authors.lastname: Marcacci
authors.affiliation: Laboratory of Biomechanics and Technology Innovation/NABI, 2nd Orthopaedic and Traumatologic Clinic, Rizzoli Orthopaedic Institute, via di Barbiano 1/10, Bologna, Italy. berardo.dimatteo@gmail.com.
authors.forename: Berardo
authors.initials: B
authors.lastname: Di Matteo
authors.affiliation: Laboratory of Biomechanics and Technology Innovation/NABI, 2nd Orthopaedic and Traumatologic Clinic, Rizzoli Orthopaedic Institute, via di Barbiano 1/10, Bologna, Italy. giuseppe@filardo.eu.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Filardo
mesh_terms: D000328:Adult; D001770:Blood Bactericidal Activity; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D007962:Leukocytes / Q000382:microbiology*; D050296:Microbial Viability / Q000187:drug effects; D053657:Platelet-Rich Plasma / Q000382:microbiology*