Plasma rich in growth factors promote gingival tissue regeneration by stimulating fibroblast proliferation and migration and by blocking transforming growth factor-β1-induced myodifferentiation

Human platelet lysate: Replacing fetal bovine serum as a gold standard for human cell propagation?

The essential physiological role of platelets in wound healing and tissue repair builds the rationale for the use of human platelet derivatives in regenerative medicine. Abundant growth factors and cytokines stored in platelet granules can be naturally released by thrombin activation and clotting or artificially by freeze/thaw-mediated platelet lysis, sonication or chemical treatment. Human platelet lysate prepared by the various release strategies has been established as a suitable alternative to fetal bovine serum as culture medium supplement, enabling efficient propagation of human cells under animal serum-free conditions for a multiplicity of applications in advanced somatic cell therapy and tissue engineering. The rapidly increasing number of studies using platelet derived products for inducing human cell proliferation and differentiation has also uncovered a considerable variability of human platelet lysate preparations which limits comparability of results. The main variations discussed herein encompass aspects of donor selection, preparation of the starting material, the possibility for pooling in plasma or additive solution, the implementation of pathogen inactivation and consideration of ABO blood groups, all of which can influence applicability. This review outlines the current knowledge about human platelet lysate as a powerful additive for human cell propagation and highlights its role as a prevailing supplement for human cell culture capable to replace animal serum in a growing spectrum of applications.

PRGF exerts a cytoprotective role in zoledronic acid-treated oral cells

OBJECTIVES

Bisphosphonates-related osteonecrosis of the jaw (BRONJ) is a common problem in patients undergoing long-term administration of highly potent nitrogen-containing bisphosphonates (N-BPs). This pathology occurs via bone and soft tissue mechanism. Zoledronic acid (ZA) is the most potent intravenous N-BP used to prevent bone loss in patients with bone dysfunction. The objective of this in vitro study was to evaluate the role of different ZA concentrations on the cells from human oral cavity, as well as the potential of plasma rich in growth factors (PRGF) to overcome the negative effects of this BP.

MATERIAL AND METHODS

Primary human gingival fibroblasts and primary human alveolar osteoblasts were used. Cell proliferation was evaluated by means of a fluorescence-based method. A colorimetric assay to detect DNA fragmentation undergoing apoptosis was used to determine cell death, and the expression of both NF-κB and pNF-κB were quantified by Western blot analysis.

RESULTS

ZA had a cytotoxic effect on both human gingival fibroblasts and human alveolar osteoblasts. This BP inhibits cell proliferation, stimulates apoptosis, and induces inflammation. However, the addition of PRGF suppresses all these negative effects of the ZA.

CONCLUSIONS

PRGF shows a cytoprotective role against the negative effects of ZA on primary oral cells.

CLINICAL RELEVANCE

At present, there is no definitive treatment for bisphosphonates-related osteonecrosis of the jaw (BRONJ), being mainly palliatives. Our results revealed that PRGF has a cytoprotective role in cells exposed to zoledronic acid, thus providing a reliable adjunctive therapy for the treatment of BRONJ pathology.

Platelet-Rich Plasma Promotes Axon Regeneration, Wound Healing, and Pain Reduction: Fact or Fiction

Platelet-rich plasma (PRP) has been tested in vitro, in animal models, and clinically for its efficacy in enhancing the rate of wound healing, reducing pain associated with injuries, and promoting axon regeneration. Although extensive data indicate that PRP-released factors induce these effects, the claims are often weakened because many studies were not rigorous or controlled, the data were limited, and other studies yielded contrary results. Critical to assessing whether PRP is effective are the large number of variables in these studies, including the method of PRP preparation, which influences the composition of PRP; type of application; type of wounds; target tissues; and diverse animal models and clinical studies. All these variables raise the question of whether one can anticipate consistent influences and raise the possibility that most of the results are correct under the circumstances where PRP was tested. This review examines evidence on the potential influences of PRP and whether PRP-released factors could induce the reported influences and concludes that the preponderance of evidence suggests that PRP has the capacity to induce all the claimed influences, although this position cannot be definitively argued. Well-defined and rigorously controlled studies of the potential influences of PRP are required in which PRP is isolated and applied using consistent techniques, protocols, and models. Finally, it is concluded that, because of the purported benefits of PRP administration and the lack of adverse events, further animal and clinical studies should be performed to explore the potential influences of PRP.

Platelet-Rich Plasma Prolongs Myofibroblast Accumulation in Corneal Stroma with Incisional Wound

PURPOSE

The purpose of this study was to determine whether platelet-rich plasma (PRP) has an effect on corneal stromal cells in a rat model of wound healing following corneal incision.

MATERIALS AND METHODS

The effect of PRP on corneal wound healing in vivo was investigated in a corneal incision wound model in rats. 40 rats were wounded by deep corneal incision, and treated with either topically administered PRP (20 rats) or sodium chloride (20 rats). At 4 h and 1, 3, and 5 days after incision, α-smooth muscle actin (α SMA), SMAD2 and SMAD3 expression and apoptosis in stromal cells were evaluated by immunohistochemistry, and IL-1β mRNA expression was evaluated by real time PCR.

RESULTS

PRP-treated corneas exhibited reduced stromal cell apoptosis at day 3 and day 5 (p = 0.038, and <0.001, respectively) relative to controls. Interleukin-1β mRNA expression, however, was unchanged in PRP-treated corneas relative to controls. Topical PRP treatment resulted in a higher proportion of αSMA-positive myofibroblasts recruited to the wound site relative to control corneas. PRP did not affect activation of SMAD2 but activation of SMAD3 was significantly reduced at day 1 (p = 0.001) and dramatically increased at day 5 (p = 0.032).

CONCLUSIONS

PRP treatment resulted in suppressed stromal cell apoptosis followed by SMAD3 activation and a greater proportion of myofibroblasts present at the wound site. Suppression of stromal cell apoptosis after corneal wounding by use of a growth factor-rich formulation may lead to myofibroblast accumulation by modulation of the TGF-β pathway.

Leukocyte inclusion within a platelet rich plasma-derived fibrin scaffold stimulates a more pro-inflammatory environment and alters fibrin properties

One of the main differences among platelet-rich plasma (PRP) products is the inclusion of leukocytes that may affect the biological efficacy of these autologous preparations. The purpose of this study was to evaluate whether the addition of leukocytes modified the morphological, biomechanical and biological properties of PRP under normal and inflammatory conditions. The release of pro-inflammatory cytokines from plasma rich in growth factors (PRGF) and leukocyte-platelet rich plasma (L-PRP) scaffolds was determined by enzyme-linked immunosorbent assay (ELISA) and was significantly increased under an inflammatory condition when leukocytes were included in the PRP. Fibroblasts and osteoblasts treated with L-PRP, under an inflammatory situation, underwent a greater activation of NFĸB pathway, proliferated significantly less and secreted a higher concentration of pro-inflammatory cytokines. These cellular events were assessed through Western blot and fluorimetric and ELISA methods, respectively. Therefore, the inclusion of leukocytes induced significantly higher pro-inflammatory conditions.

Predictive SNPs for radiation-induced damage in lung cancer patients with radiotherapy: a potential strategy to individualize treatment

In the treatment of lung cancer, radiotherapy has become one of the most important therapies, despite its sometimes unpredictable side effects. As such, identifying lung cancer patients who are at high risk of developing severe radiation-induced damage (mainly radiation pneumonitis and radiation-induced esophageal toxicity) and applying effect intervention or monitoring techniques are important. Although human diversity to a certain amount is explained by clinical and dosimetric factors, the presence of specific genetic determinants also influences the occurrence of radiation-induced damage. Here we summarize the data on mechanisms of radiation pneumonitis and radiation-induced esophageal toxicity supporting the involvement of variances of genes in the evolution of radiation-induced damage. Furthermore, the available evidence from current clinical studies of genetic polymorphisms for the prediction of radiation pneumonitis and radiation-induced esophageal toxicity is discussed. Eventually, this may help to truly individualize radiotherapy, using a personal genetic profile of the most relevant genes for each lung cancer patient.

Additive effect of autologous platelet concentrates in treatment of intrabony defects: a systematic review and meta-analysis

The aim of the present review is to systematically evaluate the additive effect of autologous platelet concentrates (APCs) in treatment of intrabony defects when used along with other regenerative procedures and when used alone in terms of clinical and radiological outcomes. A search was performed in electronic databases (i.e., MEDLINE and the Cochrane Central Register of Controlled Trials) in order to identify randomized clinical trials (RCTs) assessing the additive efficacy of APCs for healing and regeneration of hard and soft tissues in patients undergoing regenerative surgical procedures for the treatment of intrabony defects, having a follow-up of at least 9 months. Included studies underwent risk of bias assessment and data extraction. The main variables evaluated for efficacy were: pocket depth (PD), clinical attachment level (CAL), radiographic bone filling, and postoperative pain. The effect of APCs adjunct was evaluated for the following procedures: open flap debridement (OFD) alone, OFD plus grafting of the defect with autogenous bone or bone substitutes, and grafting in combination with a covering membrane for guided tissue regeneration (GTR). Platelet-rich fibrin (PRF) has a significant additive effect when used along with OFD. Platelet-rich plasma (PRP) has a significant additive effect when used along with bone grafts. Conversely, PRP was found to be ineffective when used in combination with GTR procedures. No study evaluated the effect of APCs on postoperative pain. Platelet-rich plasma may be used advantageously as an adjunct to grafting materials, but not in combination with GTR, for treatment of intrabony defects. Moreover, PRF can be effective as a sole regenerative material, in combination with OFD. There is still a lack of evidence regarding the effect of PRF in combination with grafting materials and GTR, the effect of other types of APCs such as plasma rich in growth factors, and the effect of APCs on postoperative pain.

Clinical, radiographical, and histological outcomes of plasma rich in growth factors in extraction socket: a randomized controlled clinical trial

OBJECTIVES

Platelet-rich plasma has been used in the treatment of extraction socket; however, randomized controlled clinical trial is still lacking to evaluate its effect on extraction socket healing.

MATERIALS AND METHODS

Single center, assessor-blinded, parallel group, randomized controlled clinical trial was conducted. Sixty patients with indication of a simple one molar extraction in the mandible were randomized to receive plasma rich in growth factors (PRGF) or blood clot. A cross-stitch suture was placed in both groups. Clinical, radiographical, and histological assessments were performed during 10-12 weeks of follow-up.

RESULTS

Cone beam CT analysis has shown that the percentage of patients where the sockets are regenerated at ≥75 % of the baseline volume was significantly higher in PRGF group (96.7 %) than the control group (45.5 %). Pain and inflammation (day 3 and day 7) have been significantly lower in PRGF group than the control group but not at day 15. Soft tissue healing scores have been significantly higher in the test group. No serious adverse events have been occurred in both groups. Histological analysis has indicated the presence of significantly thicker keratinized epithelium and significantly higher newly formed bone in the PRGF group.

CONCLUSIONS

PRGF was associated with enhanced healing of extraction socket of mandibular molars throughout the observation period.

CLINICAL RELEVANCE

Plasma rich in growth factors could be a useful tool to enhance the healing of extraction sockets by minimizing postoperative complications and stimulating the hard and soft tissues regeneration.

Ozone dosing alters the biological potential and therapeutic outcomes of plasma rich in growth factors

BACKGROUND AND OBJECTIVE

Until now, ozone has been used in a rather empirical way. This in-vitro study investigates, for the first time, whether different ozone treatments of plasma rich in growth factors (PRGF) alter the biological properties and outcomes of this autologous platelet-rich plasma.

MATERIAL AND METHODS

Human plasma rich in growth factors was treated with ozone using one of the following protocols: a continuous-flow method; or a syringe method in which constant volumes of ozone and PRGF were mixed. In both cases, ozone was added before, during and after the addition of calcium chloride. Three ozone concentrations, of the therapeutic range 20, 40 and 80 μg/mL, were tested. Fibrin clot properties, growth factor content and the proliferative effect on primary osteoblasts and gingival fibroblasts were evaluated.

RESULTS

Ozone treatment of PRGF using the continuous flow protocol impaired formation of the fibrin scaffold, drastically reduced the levels of growth factors and significantly decreased the proliferative potential of PRGF on primary osteoblasts and gingival fibroblasts. In contrast, treatment of PRGF with ozone using the syringe method, before, during and after the coagulation process, did not alter the biological outcomes of the autologous therapy.

CONCLUSION

These findings suggest that ozone dose and the way that ozone combines with PRGF may alter the biological potential and therapeutic outcomes of PRGF.

The effect of different drugs on the preparation and biological outcomes of plasma rich in growth factors

Chronic diseases are the major contributors to the global burden of disease and involve prodigious consumption of various drugs that usually affect platelet function. The autologous technology of plasma rich in growth factors (PRGF) provides a biological approach using autologous platelets as a reservoir and local delivery of proteins to promote tissue healing. The purpose of this study was to evaluate the effect of the consumption of acetylsalicylic acid, acenocoumarol and glucosamine sulfate on the preparation as well as on the biological properties of the PRGF technology. Clotting time and platelet activation of PRGF was evaluated. The latter was performed by flow cytometry. PRGF growth factor content and the release of various biomolecules by gingival fibroblasts were quantified by enzyme-linked immunosorbent assay. Cell proliferation was evaluated by means of a fluorescence-based method and cell migration was performed on culture inserts. None of the parameters evaluated was modified by the consumption of any of the three drugs tested; only the plasma of patients who had consumed acetylsalicylic acid and acenocoumarol expressed greater gingival fibroblast migration compared to plasma control. The intake of acetylsalicylic acid, acenocoumarol and glucosamine sulfate does not alter the preparation and biological properties of the autologous technology of PRGF.

Efficacy of platelet-rich plasma applied to post-extraction retained lower third molar alveoli. A systematic review

Dental retentions have a high prevalence among the general population and their removal can involve multiple complications. The use of platelet rich plasma has been proposed in an attempt to avoid these complications, as it contains high growth factors and stimulates diverse biological functions that facilitate the healing of soft and hard tissues. Objectives: To evaluate the available scientific evidence related to the application of platelet-rich plasma in the post-extraction alveoli of a retained lower third molars. Material and Methods: A systematic review of published literature registered in the Medline, EMBASE, Cochrane and NIH databases. The following categories were included: human randomized clinical studies. Key search words were: platelet rich plasma; platelet rich plasma and oral surgery; platelet rich in growth factors and third molar. Results: Of 101 potentially valid articles, seven were selected, of which four were rejected as they failed to meet quality criteria. Three studies fulfilled all selection and quality criteria: Ogundipe et al.; Rutkowski et al.; Haraji et al. The studies all measured osteoblast activity by means of sintigraphy, and also registered pain, bleeding, inflammation, temperature, numbness as perceived by the patients, radiological bone density and the incidence of alveolar osteitis. Conclusions: Scientific evidence for the use of PRP in retained third molar surgery is poor. For this reason randomized clinical trials are needed before recommendations for the clinical application of PRP can be made.

Key words:Platelet rich plasma, lower third molar surgery, postoperative.

Platelet-rich plasma, low-level laser therapy, or their combination promotes periodontal regeneration in fenestration defects: a preliminary in vivo study

BACKGROUND

This study histomorphometrically analyzes the influence of platelet-rich plasma (PRP), low-level laser therapy (LLLT), or their combination on the healing of periodontal fenestration defects (PFDs) in rats.

METHODS

PFDs were surgically created in the mandibles of 80 rats. The animals were randomly divided into four groups: 1) C (control) and 2) PRP, defects were filled with blood clot or PRP, respectively; 3) LLLT and 4) PRP/LLLT, defects received laser irradiation, were filled with blood clot or PRP, respectively, and then irradiated again. Animals were euthanized at either 10 or 30 days post-surgery. Percentage of new bone (NB), density of newly formed bone (DNB), new cementum (NC), and extension of remaining defect (ERD) were histomorphometrically evaluated. Data were statistically analyzed (analysis of variance; Tukey test, P <0.05).

RESULTS

At 10 days, group PRP presented ERD significantly lower than group C. At 30 days, group PRP presented NB and DNB significantly greater than group C. Groups LLLT, PRP, and PRP/LLLT showed significant NC formation at 30 days, with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any group C specimen.

CONCLUSIONS

LLLT, PRP, or their combination all promoted NC formation with a functional periodontal ligament. The combination PRP/LLLT did not show additional positive effects compared to the use of either therapy alone.

Variations of circulating endothelial progenitor cells and transforming growth factor-beta-1 (TGF-β1) during thoracic radiotherapy are predictive for radiation pneumonitis

Background

The vascular endothelial cells are important targets of radiotherapy, which may be involved in the pathogenesis of radiation pneumonitis (RP). This study investigated the variations of circulating endothelial progenitor cells (EPCs) and transforming growth factor-beta-1 (TGF-β1) during three-dimensional conformal radiation therapy (3D-CRT) in patients with non–small-cell lung cancer (NSCLC) and analyzed the correlation between these variations with the occurrence of RP.

Patients and methods

From November 2008 to November 2009, eighty-four consecutive patients receiving 3D-CRT for stage III disease were evaluated prospectively. Circulating EPCs and TGF-β1 levels were measured at baseline, every 2 weeks during, and at the end of treatment. RP was evaluated prospectively at 6 weeks after 3D-CRT.

Results

Thirty-eight patients (47.5%) experienced score 1 or more of RP. The baseline levels of EPCs and TGF-β1 were analyzed, no difference was found between patients with and without RP during and after 3D-CRT. By serial measurement of TGF-β1 and EPCs levels, we found that the mean levels of EPCs in the whole population remained stable during radiotherapy, but the mean levels of TGF-β1 increased slowly during radiotherapy. TGF-β1 and EPCs levels were all significantly higher at week 2, week 4 and week 6 in patients with RP than that in patients without RP, respectively. During the period of radiation treatment, TGF-β1 levels began to increase in the first 2 weeks and became significantly higher at week 6 (P < 0.01). EPCs levels also began to increase in the first 2 weeks and reached a peak at week 4. Using an ANOVA model for repeated-measures, we found significant associations between the levels of TGF-β1 and EPCs during the course of 3D-CRT and the risk of developing RP (P < 0.01). Most of the dosimetric factors showed a significant association with RP.

Conclusion

Early variations of TGF-β1 and EPCs levels during 3D-CRT are significantly associated with the risk of RP. Variations of circulating TGF-β1 and EPCs levels during 3D-CRT may serve as independent predictive factors for RP.

Trial registration

Trials registration number: 20070618

Release kinetics of platelet-derived and plasma-derived growth factors from autologous plasma rich in growth factors

Many studies have evaluated the biological effects of platelet rich plasma reporting the final outcomes on cell and tissues. However, few studies have dealt with the kinetics of growth factor delivery by plasma rich in growth factors. Venous blood was obtained from three healthy volunteers and processed with PRGF-Endoret technology to prepare autologous plasma rich in growth factors. The gel-like fibrin scaffolds were then incubated in triplicate, in a cell culture medium to monitor the release of PDGF-AB, VEGF, HGF and IGF-I during 8 days of incubation. A leukocyte-platelet rich plasma was prepared employing the same technology and the concentrations of growth factors and interleukin-1β were determined after 24h of incubation. After each period, the medium was collected, fibrin clot was destroyed and the supernatants were stored at -80°C until analysis. The growth factor delivery is diffusion controlled with a rapid initial release by 30% of the bioactive content after 1h of incubation and a steady state release when almost 70% of the growth factor content has been delivered. Autologous fibrin matrix retained almost 30% of the amount of the growth factors after 8 days of incubation. The addition of leukocytes to the formula of platelet rich plasma did not increase the concentration of the growth factors, while it drastically increased the presence of pro-inflammatory IL-1β. Further studies employing an in vitro inflammatory model would be interesting to study the difference in growth factors and pro-inflammatory cytokines between leukocyte-free and leukocyte-rich platelet rich plasma.

An autologous platelet-rich plasma stimulates periodontal ligament regeneration

BACKGROUND

Regeneration of periodontal tissues is one of the most important goals for the treatment of periodontal disease. The technology of plasma rich in growth factors provides a biologic approach for the stimulation and acceleration of tissue healing. The purpose of this study is to evaluate the biologic effects of this technology on primary human periodontal ligament fibroblasts.

METHODS

The authors studied the response of periodontal ligament cells to this pool of growth factors on cell proliferation, cell migration, secretion of several biomolecules, cell adhesion, and expression of α2 integrin. Cell proliferation and adhesion were evaluated by means of a fluorescence-based method. Cell migration was performed on culture inserts. The release of different biomolecules by periodontal ligament fibroblasts was quantified through enzyme-linked immunosorbent assay. The α2 integrin expression was assessed through Western blot.

RESULTS

This autologous technology significantly stimulated cell proliferation, migration, adhesion, and synthesis of many growth factors from cells including vascular endothelial growth factor, thrombospondin 1, connective tissue growth factor, hepatocyte growth factor, and procollagen type I. The α2 integrin expression was lower in plasma rich in growth factor-treated cells compared to non-stimulated cells, although no statistically significant differences were observed.

CONCLUSION

This plasma rich in growth factors exerts positive effects on periodontal ligament fibroblasts, which could be positive for periodontal regeneration.

Plasma rich in growth factors promotes bone tissue regeneration by stimulating proliferation, migration, and autocrine secretion in primary human osteoblasts

BACKGROUND

Alveolar bone loss can be a major clinical concern affecting both functionality and esthetics. Osteoblasts are the main cells charged with the repair and regeneration of missing bone tissue. Plasma rich in growth factors (PRGF) allows delivery of a cocktail of proteins and growth factors that promote wound healing and tissue regeneration to the site of injury. This study tests the effect of this endogenous regenerative technology to stimulate alveolar osteoblast bone-forming potential.

METHODS

Primary human osteoblasts were retrieved from alveolar bone of patients undergoing oral surgery. Cell proliferation was evaluated, and culture inserts and permeable transwell supports were used to assess cell migration and chemotaxis. The expression of differentiation markers was quantified by enzyme-linked immunosorbent assay.

RESULTS

PRGF succeeded in increasing proliferation, migration, and chemotaxis of osteoblasts. Also, PRGF significantly enhanced the autocrine expression of two relevant proangiogenic factors, vascular endothelial growth factor and hepatocyte growth factor, and three markers of osteoblastic activity, procollagen I, osteocalcin, and alkaline phosphatase.

CONCLUSION

The results indicate that PRGF can stimulate some of the biologic processes of the main cells responsible for bone regeneration and help support the positive clinical outcomes that have been reported with this technology.

Inactivation of epidermal growth factor by Porphyromonas gingivalis as a potential mechanism for periodontal tissue damage

Porphyromonas gingivalis is a Gram-negative bacterium associated with the development of periodontitis. The evolutionary success of this pathogen results directly from the presence of numerous virulence factors, including peptidylarginine deiminase (PPAD), an enzyme that converts arginine to citrulline in proteins and peptides. Such posttranslational modification is thought to affect the function of many different signaling molecules. Taking into account the importance of tissue remodeling and repair mechanisms for periodontal homeostasis, which are orchestrated by ligands of the epidermal growth factor receptor (EGFR), we investigated the ability of PPAD to distort cross talk between the epithelium and the epidermal growth factor (EGF) signaling pathway. We found that EGF preincubation with purified recombinant PPAD, or a wild-type strain of P. gingivalis, but not with a PPAD-deficient isogenic mutant, efficiently hindered the ability of the growth factor to stimulate epidermal cell proliferation and migration. In addition, PPAD abrogated EGFR-EGF interaction-dependent stimulation of expression of suppressor of cytokine signaling 3 and interferon regulatory factor 1. Biochemical analysis clearly showed that the PPAD-exerted effects on EGF activities were solely due to deimination of the C-terminal arginine. Interestingly, citrullination of two internal Arg residues with human endogenous peptidylarginine deiminases did not alter EFG function, arguing that the C-terminal arginine is essential for EGF biological activity. Cumulatively, these data suggest that the PPAD-activity-abrogating EGF function in gingival pockets may at least partially contribute to tissue damage and delayed healing within P. gingivalis-infected periodontia.