Antibacterial effect of plasma rich in growth factors (PRGF®-Endoret®) against Staphylococcus aureus and Staphylococcus epidermidis strains.
ABSTRACT Formulations containing plasma rich in growth factors (PRGF) are opening new avenues in the field of regenerative medicine.
To evaluate the potential antimicrobial effects of a product (plasma rich in growth factors; PRGF(®)-Endoret(®)) against both methicillin-sensitive and methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. The potential effect of incorporating the patient's leucocytes into the PRGF formulation (F3+leu) was also studied.
Blood samples were obtained from five healthy volunteers and used to prepare each type of PRGF (F1, F3 and F3+leu). Various biological assays were performed to compare the characteristics of the different formulations, including measurement of the concentration of platelets and leucocytes, and assays of coagulation. The microbiological activity of PRGF-Endoret against both staphylococcal strains was performed by counting the number of the surviving bacterial colonies after incubation at 0, 4 and 8 h with the different formulations.
The three PRGF-Endoret formulations evaluated were enriched in platelets by 1.10, 2.57 and 1.89 times, respectively, and the leucocyte concentration in the F3+leu sample was increased by 3.9 times. We found that all formulations had a strong bacteriostatic effect, especially in the first 4 h after application. All formulations had an antibacterial effect at 4 h for three of the four strains, with the exception of methicillin-sensitive S. epidermidis. No differences in the bacterial inhibitory effect were found between the formulations.
This is the first time different formulations of this product have been evaluated, and the results suggest that PRGF-Endoret could be used in the fight against postoperative and wound infections.
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ABSTRACT: Platelets share structural and functional similarities with granulocytes known to participate in antimicrobial host defense. To evaluate the potential antimicrobial activities of platelet proteins, normal human platelets were stimulated with human thrombin in vitro. Components of the stimulated-platelet supernatants were purified to homogeneity by reversed-phase high-performance liquid chromatography. Purified peptides with inhibitory activity against Escherichia coli ML35 in an agar diffusion antimicrobial assay were characterized by mass spectrometry, amino acid analysis, and sequence determination. These analyses enabled the identification of seven thrombin-releasable antimicrobial peptides from human platelets: platelet factor 4 (PF-4), RANTES, connective tissue activating peptide 3 (CTAP-3), platelet basic protein, thymosin beta-4 (Tbeta-4), fibrinopeptide B (FP-B), and fibrinopeptide A (FP-A). With the exception of FP-A and FP-B, all peptides were also purified from acid extracts of nonstimulated platelets. The in vitro antimicrobial activities of the seven released peptides were further tested against bacteria (E. coli and Staphylococcus aureus) and fungi (Candida albicans and Cryptococcus neoformans). Each peptide exerted activity against at least two organisms. Generally, the peptides were more potent against bacteria than fungi, activity was greater at acidic pHs, and antimicrobial activities were dose dependent. Exceptions to these observations were observed with PF-4, which displayed a bimodal dose-response relationship in microbicidal assays, and Tbeta-4, which had greater activity at alkaline pHs. At concentrations at which they were individually sublethal, PF-4 and CTAP-3 exerted synergistic microbicidal activity against E. coli. Collectively, these findings suggest a direct antimicrobial role for platelets as they are activated to release peptides in response to trauma or mediators of inflammation.Infection and Immunity 01/2003; 70(12):6524-33. · 4.07 Impact Factor
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ABSTRACT: Platelet microbicidal proteins (PMPs), small cationic peptides released at sites of endovascular damage, kill common bloodstream pathogens in vitro. Our group previously showed that in vitro resistance of clinical staphylococcal and viridans group streptococcal bacteremic strains to PMPs correlated with the diagnosis of infective endocarditis (IE) (Wu et al., Antimicrob. Agents Chemother. 38:729-732, 1994). However, that study was limited by (i) the small number of Staphylococcus aureus isolates from IE patients, (ii) the retrospective nature of the case definitions, and (iii) the diverse geographic sources of strains. The present study evaluated the in vitro PMP susceptibility phenotype of a large number of staphylococcemic isolates (n = 60), collected at a single medical center and categorized by defined and validated clinical criteria. A significantly higher proportion of staphylococcemic strains from patients with IE was PMP resistant in vitro than the proportion of strains from patients with soft tissue sepsis (83% and 33%, respectively; P < 0.01). Moreover, the levels of PMP resistance (mean percent survival of strains after 2-h exposure to PMP in vitro) were significantly higher for isolates from patients with IE and with vascular catheter sepsis than for strains from patients with abscess sepsis (P < 0.005 and P < 0.01, respectively). These data further support the concept that bloodstream pathogens that exhibit innate or acquired PMP resistance have a survival advantage with respect to either the induction or progression of endovascular infections.Antimicrobial Agents and Chemotherapy 01/1999; 42(12):3169-72. · 4.57 Impact Factor
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ABSTRACT: Mammalian platelets contain small, cationic, staphylocidal peptides, termed thrombin-induced platelet-microbicidal proteins (tPMPs). Evidence suggests that tPMPs play a key role in host defense against endovascular infections, such as infective endocarditis (IE). In the present study, we evaluated the influence of differences in staphylococcal tPMP-susceptibility profiles in vitro on disease severity in experimental IE. Experimental IE was induced in rabbits with either a tPMP-susceptible or an isogenic tPMP-resistant Staphylococcus aureus strain. Vegetation size, left ventricular fractional shortening, and onset of aortic valvular regurgitation were serially assessed by echocardiography over an 11-day postinfection period. In addition, blood cultures were performed daily. Parameters delineated at autopsy included vegetation weights; bacterial densities in vegetations, myocardium, and kidneys; extent of valvular and perivalvular tissue damage; and renal embolization. The following significant differences were observed in animals infected with the tPMP-susceptible versus the tPMP-resistant S aureus strain: substantially lower bacteremia rates (P=0.02); reduced vegetation growth (P<0.001) and weight (P<0.001); a later onset of aortic valvular regurgitation (P=0.0039); increased preservation of left ventricular function (P<0.001); reduced valvular tissue damage (P=0.01) and perivalvular inflammation (P=0.015); and reduced bacterial densities in vegetations (P<0.001) and kidneys (P<0.01). The in vitro tPMP-susceptibility profile in S aureus substantially affects a number of well-defined cardiac and microbiological parameters related to disease severity and prognosis in IE. These findings underscore the likelihood that platelets mitigate the pathogenesis of endovascular infections via local secretion of antimicrobial peptides.Circulation 03/2002; 105(6):746-52. · 15.20 Impact Factor