Perspective Platelet-rich plasma: a healing virtuoso

Platelets, 2013

Platelet derivatives are commonly used in wound healing and tissue regeneration. Different procedures of platelet preparation may differentially affect growth factor release and cell growth. Preparation of platelet-rich fibrin (PRF) is accompanied by release of growth factors, including platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and transforming growth factor b1 (TGFb1), and several cytokines. When compared with the standard procedure for platelet-rich plasma (PRP), PRF released 2-fold less PDGF, but 415-fold and 42-fold VEGF and TGFb1, respectively. Also, the release of several cytokines (IL-4, IL-6, IL-8, IL-10, IFNg, MIP-1a, MIP-1b and TNFa) was significantly increased in PRF-conditioned medium (CM), compared to PRP-CM. Incubation of both human skin fibroblasts and human umbilical vein endothelial cells (HUVECs) with PRF-derived membrane (mPRF) or with PRF-CM enhanced cell proliferation by 42-fold (p50.05). Interestingly, PRP elicited fibroblast growth at a higher extent compared to PRF. At variance, PRF effect on HUVEC growth was significantly greater than that of PRP, consistent with a higher concentration of VEGF in the PRF-CM. Thus, the procedure of PRP preparation leads to a larger release of PDGF, as a possible result of platelet degranulation, while PRF enhances the release of proangiogenic factors.

The therapeutic basis of platelet-rich plasma use in medicine is derived from the growth factor content and provisional matrix provided by the platelets themselves. This chapter briefly reviews the platelet research which led to the conceptual development of PRP as a treatment and also the early history of its use. An overview of platelet structure and function is provided to enhance the clini-cian's understanding of the cell biology behind PRP therapy. The 2 major growth factors in PRP (PDGF and TGFb) are also discussed. Finally, a review of the experimental PRP literature (in vitro and animal studies) is presented, which describes the evidence for use of PRP in tendon/ligament, bone, and joints. Standardization of PRP use remains a challenging prospect due to the number of variables involved in its preparation and administration. It may be that individually tailored PRP protocols are actually more beneficial for our patients—only time and further research will bear this out. Origins and Overview of PRP Use in Medicine As recently as forty years ago, platelets were considered to be exclusively hemostatic cells. Today we know that platelets actually perform myriad diverse functions. The conventional paradigm of limited platelet function began to shift in 1974, as the pathogenesis of atherosclerosis was beginning to be unraveled. Researchers studying the proliferation of smooth muscle cells in the vascular intima knew that 10 % serum was crucial to support cell growth in culture, but did not know which component of serum was responsible for the observed anabolic

International journal of implant dentistry, 2016

The development of platelet-rich fibrin (PRF) drastically simplified the preparation procedure of platelet-concentrated biomaterials, such as platelet-rich plasma (PRP), and facilitated their clinical application. PRF's clinical effectiveness has often been demonstrated in pre-clinical and clinical studies; however, it is still controversial whether growth factors are significantly concentrated in PRF preparations to facilitate wound healing and tissue regeneration. To address this matter, we performed a comparative study of growth factor contents in PRP and its derivatives, such as advanced PRF (A-PRF) and concentrated growth factors (CGF). PRP and its derivatives were prepared from the same peripheral blood samples collected from healthy donors. A-PRF and CGF preparations were homogenized and centrifuged to produce extracts. Platelet and white blood cell counts in A-PRF and CGF preparations were determined by subtracting those counts in red blood cell fractions, supernatant ac...

Orthopedic Research and Reviews

Platelet-rich plasma (PRP) contains many growth factors, such as FGF, which induces the production of type I collagen, and VEGF, which induces neovascularization, all of which are important in bone healing. This study aimed to evaluate the effect of PRP administration on type I collagen production, VEGF expression, and neovascularization in rat models following femoral bone implants using K-wire. Methods: An experimental randomized control study was conducted on 24 white male rats (Rattus norvegicus) in the Wistar strain that underwent K-wire implantation, where PRP was administered to the treatment groups. The amount of type I collagen was measured by immunohistochemistry VEGF expression using sandwich ELISA, and neovascularization by histopathological examination. Results: The amount of type I collagen in the treatment group (50->150/field of view) was significantly higher than the control group (0-99/field of view; p=0.003). VEGF expression in the treatment groups was significantly higher than controls: 10.90±4.47 and 2.29 ±0.92, respectively (p=0.006). Mean number of new vessels formed on fibrotic capsules in the treatment groups was significantly (p=0.007) higher than the control groups (2.69±1.03 vs 0.67±0.52). Conclusion: The use of PRP significantly increased type I collagen production, VEGF expression, and neovascularization in rat models, elucidating the potential of PRP to be used in clinical settings to enhance the bone-healing process.

Journal of Clinical and Molecular Medicine, 2018

Thrombosis and Haemostasis, 2003

SummaryPlatelets are known for their role in haemostasis where they help prevent blood loss at sites of vascular injury. To do this, they adhere, aggregate and form a procoagulant surface leading to thrombin generation and fibrin formation. Platelets also release substances that promote tissue repair and influence the reactivity of vascular and other blood cells in angiogenesis and inflammation. They contain storage pools of growth factors including PDGF, TGF-β and VEGF as well as cytokines including proteins such as PF4 and CD40L. Chemokines and newly synthesised active metabolites are also released. The fact that platelets secrete growth factors and active metabolites means that their applied use can have a positive influence in clinical situations requiring rapid healing and tissue regeneration. Their administration in fibrin clot or fibrin glue provides an adhesive support that can confine secretion to a chosen site. Additionally, the presentation of growth factors attached to p...

The Journal of Dentists, 2013

PDGF and VEGF are two of the most potent mitogen for connective tissue, its secretion appears to be particularly important when the source is Platelet Rich Plasma (PRP), hence the latter leading role in tissue regeneration. ELISA PDGFBB levels in PRP, Platelet Poor Plasma (PPP) and exudates, were determined in 32 healthy subjects before and 24 hours after ingestion of Aspirin (ASA) and Clopidogrel (CLO). Results: PDGFBB baseline levels were 10.6 ± 1.9 ng / ml (PPP), 12.12 ± 2.5 ng / ml (PRP) and 10.84 ± 1.68 ng / ml (exudate) While after treatment with PDGFBB ASA concentrations were at 8.96 ± 1.4 ng / ml (PPP), 11.36 ± 1.48 ng / ml (PRP), 11.11 ± 1.14 ng / ml (exudate) and the Clopidogrel were 8.53 ± 0.59 ng / ml (PPP), 9.65 ± 1.17 ng / ml (PRP) and 8.51 ± 0.75 ng / ml (exudate) . VEGF basal values were 973.9 ± 590.3 pg / ml (PPP), 1184.2 ± 288.4 pg / ml (PRP), 1069.3 ± 192.3 pg / ml (exudate). After treatment with ASA VEGF values ??were at 1439.5 ± 117.4 pg / ml (PPP), 1802.3 ± 123...

Clinical cases in mineral and bone metabolism : the official journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases, 2011

Platelet-rich plasma (PRP) is defined as a portion of the plasma fraction of autologous blood having platelet concentrations above baseline. When activated the platelets release growth factors that play an essential role in bone healing such as Platelet-derived Growth Factor, Transforming Growth Factor-β, Vascular Endothelial Growth Factor and others.Multiple basic science and in vivo animal studies agree that PRP has a role in the stimulation of the healing cascade in ligament, tendon, muscle cartilage and in bone regeneration in the last years PRP had a widespread diffusion in the treatment of soft tissue and bone healing.The purpose of this review is to describe the biological properties of platelets and its factors, the methods used for producing PRP, to provide a background on the underlying basic science and an overview of evidence based medicine on clinical application of PRP in bone healing.

BioMed Research International, 2016

Platelet-Rich Plasma (PRP) is a low-cost procedure to deliver high concentrations of autologous growth factors (GFs). Platelet activation is a crucial step that might influence the availability of bioactive molecules and therefore tissue healing. Activation of PRP from ten voluntary healthy males was performed by adding 10% of CaCl2, 10% of autologous thrombin, 10% of a mixture of CaCl2+ thrombin, and 10% of collagen type I. Blood derivatives were incubated for 15 and 30 minutes and 1, 2, and 24 hours and samples were evaluated for the release of VEGF, TGF-β1, PDGF-AB, IL-1β, and TNF-α. PRP activated with CaCl2, thrombin, and CaCl2/thrombin formed clots detected from the 15-minute evaluation, whereas in collagen-type-I-activated samples no clot formation was noticed. Collagen type I produced an overall lower GF release. Thrombin, CaCl2/thrombin, and collagen type I activated PRPs showed an immediate release of PDGF and TGF-β1that remained stable over time, whereas VEGF showed an inc...

Biomedicine

Introduction and Aim: Activated autologous platelet-rich plasma (aaPRP) is becoming a popular therapy to accelerate healing in the field of plastic surgery. Platelets, which are abundant in aaPRP, can release many growth factors including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). This study aims to examine the plasma levels of PDGF and VEGF in healthy subjects after intravenous administration of aaPRP. Materials and Methods: Nine healthy patients with no prior history of metabolic disease were divided into two groups (control and experiment group). The treatment group which consists of six patients received intravenous aaPRP treatment. The preparation of aaPRP starts with the collection of 24 mL of whole blood in sodium citrate tubes followed a two-step centrifugation procedure and subsequent chemical activation. aaPRP was then administered intravenously to patients. Meanwhile, the control group received no intervention. Venous blood samp...

Journal of Thrombosis and Haemostasis, 2003

Background: Vascular endothelial growth factor (VEGF) is an endothelial cell-speci®c potent mitogen that induces angiogenesis and microvascular hyperpermeability. Recently, it has been reported that megakaryocytes and platelets contain VEGF in their cytoplasm. Objectives: To elucidate and con®rm the bioactivity and role of VEGF in platelets (platelet VEGF), which may be closely related to vascular thrombosis and atherosclerosis. Methods: The VEGF localization in megakaryocytes on bone marrow smears was analyzed by immunouorescence and confocal laser scanning microscopic analysis. The intracellular VEGF expressed in platelets was determined by¯ow cytometric analysis. Platelet-rich plasma and washed platelets were used to analyze the secretion of VEGF during platelet aggregation by thrombin or gelatinase A (matrix metalloproteinase-2) stimulation. Immunohistochemical studies for VEGF in the thrombotic region were performed. Results and conclusions: Megakaryocytes and platelets are a very rich source of circulating VEGF. Gelatinase A, which is closely associated with vascular remodeling, enhances the VEGF levels released from platelets. VEGF was clearly detected in the ®brin nets of a thrombus. Taken together, platelet VEGF is bioactive as a direct angiogenic growth factor, and may play a very important role in wound healing and atherosclerosis in conjunction with other platelet cytokines such as platelet-derived growth factor, platelet-derived endothelial cell growth factor, transforming growth factor (TGF)-a, and TGF-b.

Acta Oncologica, 1993

Platelet-derived Growth Factor Structure, Function, and Roles in Normal and Transformed Cells Polypeptide growth factors regulate the proliferation of cells in culture alone or in concert with other mitogens by inducing DNA synthesis and cell division in specific target cells. The mechanisms of action and the in vivo functions of these polypeptide growth factors are not known. It seems likely that growth factors have some role in cell development, differentiation, and tissue repair. Of the known growth factors, epidermal growth factor (EGF),' the platelet-derived growth factor (PDGF), and nerve growth factor are best defined. Each interacts with target cells through specific cell-surface receptors, leading to DNA synthesis, cell proliferation, and morphological and biochemical changes which resemble those characteristic of cells transformed by acute retroviruses (1-5). Malignant transformed cells also synthesize and secrete polypeptide growth factors which may stimulate autonomous cellular proliferation by an autocrine mechanism (6). In this article, we will summarize results of recent studies on the structure and biology of one well-characterized growth factor, PDGF, and attempt to relate how PDGF and perhaps PDGF-like molecules may play important roles in malignant transformation and cell growth of virus-transformed cells. Origins ofPDGF Platelets do not bind to intact endothelium. PDGF is contained in alpha granules of platelets and is released only during blood clotting or when platelets adhere at sites of blood vessel injury. Secretion of platelet contents can be initiated by exposure of platelets to foreign surfaces such as subendothelial basement membrane or collagen (7-9). PDGF may serve to promote wound healing since it is the most potent mitogen in serum for cells of mesenchymal origins, including fibroblasts, glial cells, and smooth muscle cells (10, 11). Cells ordinarily are Receivedfor publication I May 1984.

Archives of Orthopaedic and Trauma Surgery, 2013

Journal of Vascular Surgery, 1988

Neointimal fibromuscular hyperplasia (NFH) in vein grafts and perianastomotic zones of vascular prostheses has been attributed to the effects of platelet-derived growth factor (PDGF) released by platelets interacting with bypass conduits. But inhibition of platelet aggregation often fails to prevent NFH, and recurrent growth of intact, platelet-free endothelium over perianastomotic areas where NFH occurs is inconsistent with the concept of sustained PDGF release from platelets causing NFH progression at late times after surgical procedures. Cultured bovine aortic endothelial cells (ECs) and human umbilical vein ECs have been shown to release a PDGF-like molecule. We report that confluent cultured fourth passage adult human saphenous vein ECs (AHSVECs) grown in the presence of heparin (100 micrograms/ml) and retina-derived growth factor (RDGF) studied by Northern blotting transcribed a messenger ribonucleic acid (mRNA) of 3.9 kb, strongly hybridizing to PDGF B chain probes, and two species of 2.0 and 2.6 kb hybridizing to PDGF A chain probes. Withdrawal of RDGF and heparin from these cultures for 48 hours before mRNA extraction amplified the scanning densitometric mRNA signal per cell by 8.0 +/- 7.6 fold (mean +/- SD) (N = 4 cultures) for B chain mRNA and 5.2 +/- 3.6 fold (N = 3 cultures) for A chain mRNA. In addition, AHSVEC cultures released a PDGF-like substance, because 50% vol/vol AHSVEC-conditioned serum-free medium increased tritiated thymidine uptake elevenfold in PDGF receptor-bearing 3T3 cells whereas an excess (50 micrograms/ml) of nonspecific goat anti-human-PDGF antibody significantly reduced this increase by a mean of 30% to 7.0 +/- 3.4 fold (N = 6 trials, p less than 0.001). Flow cytometry determined AHSVEC cultures to be proliferating with a mean of 6.2% +/- 1.9% (N = 3 culture lines) of ECs in S phase even at confluence when deprived of EC mitogens for 48 hours. Adult human ECs, which proliferate on bypass conduits and host vessels after perioperative injury, may play a role in causing NFH by stimulating proliferation of adjacent smooth muscle cells. Prevention of NFH may require not only antiplatelet agents but also ways to prevent EC release of smooth muscle cell mitogens in response to perioperative EC injury.