Platelet-enriched Plasma Research Articles

In vitro biocompatibility evaluation of ePTFE graft with controlled release of heparin from mesoporous material

Heparin-loaded mesoporous-expanded poly(tetrafluoroethylene) (ePTFE) vascular prosthesis (HMVP-n) are prepared and the biocompatibility is studied by contact angle, heparin release, platelet resistance, chromogenic assay, endothelial progenitor cells (EPCs) proliferation and produced-NO function, in order to illustrate the relationship between the performance of artificial vessels and their mesostructure. Through in situ synthesis of mesoporous silica on ePTFE grafts, different mesoporous silica materials can be uniformly coated on the surface as well as the internal fibers of the artificial vessels to give various mesoporous vascular prosthesis, named as MVP-n. Structure analysis through scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX) analysis and nitrogen sorption experiment indicates that different MVP-n series own the similar nF/nSi ratio of both surface and cross-section, large Brunauer-Emmett-Tellerand (BET) surface area and average pore size located in meso range but different textural properties. Owning to the existence of mesostucture, controlled release and high bioactivity of heparin can be achieved, and the biocompatibility greatly enhance: surface hydrophilicity increases; no adherent platelet was observed on the surface of HMVP-n when they contacted with platelet-enriched plasma; endothelial progenitor cells proliferous potential and produced-NO function exhibit better endothelial coverage of grafts. And the performance is closely related to the mesostructure, suggesting a new way to improve the biocompatibility of biomaterials through controlling their mesostructure.

Plasma Rich in Growth Factors (PRGF-Endoret) Stimulates Proliferation and Migration of Primary Keratocytes and Conjunctival Fibroblasts and Inhibits and Reverts TGF-β1–Induced Myodifferentiation

Plasma rich in growth factors (PRGF-Endoret) technology is an autologous platelet-enriched plasma obtained from patient's own blood, which after activation with calcium chloride allows the release of a pool of biologically active proteins that influence and promote a range of biological processes including cell recruitment, and growth and differentiation. Because ocular surface wound healing is mediated by different growth factors, we decided to explore the potential of PRGF-Endoret technology in stimulating the biological processes related with fibroblast-induced tissue repair. Furthermore, the anti-fibrotic properties of this technology were also studied. Blood from healthy donors was collected, centrifuged and, whole plasma column (WP) and the plasma fraction with the highest platelet concentration (F3) were drawn off, avoiding the buffy coat. Primary human cells including keratocytes and conjunctival fibroblasts were used to perform the "in vitro" investigations. The potential of PRGF-Endoret in promoting wound healing was evaluated by means of a proliferation and migration assays. Fibroblast cells were induced to myofibroblast differentiation after the treatment with 2.5 ng/mL of TGF-β1. The capability of WP and F3 to prevent and inhibit TGF-β1-induced differentiation was evaluated. Results show that this autologous approach significantly enhances proliferation and migration of both keratocytes and conjunctival fibroblasts. In addition, plasma rich in growth factors prevents and inhibits TGF-β1-induced myofibroblast differentiation. No differences were found between WP and F3 plasma fractions. These results suggest that PRGF-Endoret could reduce scarring while stimulating wound healing in ocular surface. F3 or whole plasma column show similar biological effects in keratocytes and conjunctival fibroblast cells.

Long-term Regulation of Genetically Modified Primary Hematopoietic Cells in Dogs

We report long-term results from a large animal model of in vivo selection. Nine years ago, we transplanted two dogs (E900 and E958) with autologous marrow CD34(+) cells that had been transduced with a gammaretrovirus vector encoding a conditionally activatable derivative of the thrombopoietin receptor. Receptor activation through administration of a chemical inducer of dimerization (CID) (AP20187 or AP1903) confers a growth advantage. We previously reported responses to two 30-day intravenous (i.v.) courses of AP20187 administered within the first 8 months post-transplantation. We now report responses to 5-day subcutaneous (s.c.) courses of AP20187 or AP1903 at months 14, 90, and 93 (E900), or month 18 (E958), after transplantation. Long-term monitoring showed no rise in transduced cells in the absence of drug. Retroviral insertion site analysis showed that 4 of 6 (E958) and 5 of 12 (E900) transduced hematopoietic cell clones persisted lifelong. Both dogs were euthanized for reasons unrelated to the gene therapy treatment at 8 years 11 months (E958) and 11 years 1 month (E900) of age. Three clones from E900 remained detectable in each of two secondary recipients, one of which was treated with, and responded to, AP1903. Our results demonstrate the feasibility of safely regulating genetically engineered hematopoietic cells over many years.

Neovasculogenesis stimulation is a new trend in the treatment of chronic arterial occlusive diseases of lower extremities

An analysis of experimental investigation of 70 male Vistar rates and results of examination and treatment of 30 patients suffered by chronic low limbs ischemia caused by atherosclerosis has been completed. All experimental animals were divided into three groups: healthy, control, and investigated respectively. A chronic limb ischemia was achieved by excision of the main vessel such as femoral, popliteal, and upper part of calf vessels. Having achieved an ischemia a treatment was not done in the control group. Whereas animals of the control group received injection of platelet enriched autoplasm into the calf and thigh muscles. It was discovered that intramascular injection of platelet enriched autoplasm into the animals ischemic limb increases microcirculation level 2,4 times and dicreases area of muscular necrosis by 2,4 times to 28 experimental day. In patients 500 ml of blood were derived, from which a platelet enriched plasma was made. 100 ml of the plasma were injected under ultrasound guidance along the deep femoral and popliteal arteries of the more 2nd b degree ischemic limb. A contralateral limb was used as a control group. After the treatment a blood flow volume was increased 1,4 times, main 885,08 in 1,3 times, and microcirculation level in 1,2 times.

Platelet-Enriched Plasma and Muscle Strain Injuries: Challenges Imposed by the Burden of Proof

To review the evidence for the clinical utilization of autologous plasma products in the management of muscle strain injuries. Systematic review using EMBASE and MEDLINE (up to March 2010). There is no level 1, 2, and 3 evidence for the use of autologous plasma products in muscle strain injuries. Furthermore, significant methodological limitations impact on the interpretation of the few published studies in this field. Although basic science and the use of recombinant growth factors in animal models support the concept of applying growth factors to acute muscle injuries, it is unclear if this evidence can be directly translated to reflect outcomes from platelet-enriched plasma. There remain a large number of unanswered questions, including the principle questions regarding safety and efficacy, which require appropriate scientific investigation. It is incumbent on sports physicians wishing to enhance athlete care, together with researchers, to search for these answers.

Caption™: a filtration-based platelet concentration system

Despite significant advances, wound management remains a medical challenge and a major health-expense problem. Currently, a wide range of therapeutic interventions are available for wound care. This is only partially explained by the variability in the presenting clinical situation and shows that there is no panacea for this complex medical problem. Over time, a multitude of interventions have been proposed as solutions for faster and more effective healing; however, only a few are still part of the wound care armamentarium today. Based on the fact that platelets contain a high concentration of growth factors, the application of platelet-enriched plasma over wound sites was recently introduced as a novel therapeutic modality. As increasing evidence started to validate its benefit, several devices for platelet-rich plasma preparation became available. Here, we present the most recently introduced platelet concentration system and provide insights on the current and possible future applications of this treatment modality.

Regenerative medicine: a review

Regenerative medicine is a technique to replace or repair defective or diseased tissue or organs by in vitro design with in vivo usage. It can be considered a relatively new branch of medicine born in 1997 when Whithman DH et al. proposed to integrate platelet enriched plasma (PRP) in fibrin glue. In 1998 Marx et al. demonstrated that PRP was able to induce bone regeneration of the jaw. In the same period it was discovered that a fraction of stem cells of bone marrow origin was able to repair several mesenchymal tissues or organs.

Engraftment in NOD/SCID Mice of TPO Amplified CB Cells To Promote Platelet Development.

A major disadvantage of human umbilical cord blood (CB) transplant is the delayed engraftment of platelets, which can lead to hemorrhagic complication, increased platelet transfusion requirements, prolonged alloimmunization and hospitalization. As a strategy for accelerating platelet recovery, the infusion of ex vivo expanded megakaryocytic progenitors to transplant patients has been proposed. NOD/SCID mice constitute an in vivo model to study human megakaryocytopiesis and platelet development after transplantation. CB was obtained from the placenta of full-term newborn, after informed consent provided according to the Declaration of Helsinki, CD34+ progenitors with amplified 100ng/ml thrombopoietin (TPO) were transplanted in NOD/SCID mice, and their ability to promote differentiation of the megakaryocytic lineage, with production of functional platelets was assessed. The engraftment was evaluated on bone marrow cells by flow cytometry analysis using human CD45 MoAb staining. Four weeks after transplantation, a mean value of 3.22% CD45+ human cells was obtained; this percentage significantly increased at week 8 (39.6% hCD45+ cells) and was observed to have remained constant at week 12 (45.6% hCD45+ cells). To evaluate the capacity of engrafted cells to produce platelets, we performed Facs analysis to monitor the appearance of human platelets in mouse peripheral blood. Mouse peripheral blood was collected via retro-orbital bleeding at different times (2, 4, 6 and 8 weeks) in EDTA-coated tubes. Platelet enriched plasma was analyzed after human CD41a-FITC staining by flow cytometry. Of the mice analyzed, 78.8% produced >0.1% human platelets. The results obtained with CB CD34+ cells amplified with TPO were compared with cells amplified in the presence of a cocktail of growth factors (100ng/ml KL, 50ng/ml FL, 10ng/ml IL6) containing TPO at low concentration (10ng/ml) (T10KF6) or high concentration (100ng/ml) (T100KF6). The mean engraftment values were 57.7% in the T10KF6 group and 10.0% in T100KF6 group. However, although reduced engraftment was obtained in T100KF6, a mean of 60.8% of mice produced (>0.1%) human platelets. In T10KF6 this percentage was reduced to 45.2%. Despite the strong variability in platelets production, a mean percentage of 0.49% human platelets was detected at week 2 after transplantation; at week 4, this percentage peaked, reaching 1.26% (which translated into 7.6×109/L total human platelet count). In some mice, a human platelet percentage of 7% (42.2×109/L) was obtained. The platelet count gradually decreased between weeks 6 and 8, with a mean of 1.02% (8.05×109/L) and 0.86% (7.99×109/L) respectively. Our results showed that TPO maintained about 2.2 times higher platelet count than T100KF6 and T10KF6 and that TPO might play an important role in the ex vivo expansion of haematopoietic cells, supporting the hypothesis that Mk lineage engraftment is capable of shortening time of human platelet recovery when transplanted in NOD/SCID mice.

Functional Recovery after Peripheral Nerve Repair Associated with Transplanted Bone Marrow, Adult Mesenchymal Stem Cells, and Platelet-Enriched Plasma

Functional Recovery after Peripheral Nerve Repair Associated with Transplanted Bone Marrow, Adult Mesenchymal Stem Cells, and Platelet-Enriched Plasma

Effect of platelet‐rich plasma on migration and proliferation of SaOS‐2 osteoblasts: role of platelet‐derived growth factor and transforming growth factor‐β

Platelet-enriched plasma (PRP) is used in therapy as a source of growth factors in bone fracture and wound healing; however, few data exist on its role in the different aspects of the healing process. The effect of PRP and of the two main growth factors present in this preparation (platelet-derived growth factor [PDGF] and transforming growth factor-beta [TGF-beta]) was evaluated in vitro using the human osteoblastic cell line SaOS-2, which was shown by reverse transcription-polymerase chain reaction to express both PDGF-alpha and -beta receptors. Batroxobine-activated PRP was added in different concentrations to SaOS-2 cells to assess cell migration (by a microchemotaxis assay) and cell proliferation (by [3H]-thymidine incorporation into the DNA). Immunoneutralization with anti-PDGF-beta or anti-TGF-beta antibodies allowed the assessment of the specific role of these growth factors. The overall results obtained indicate that PRP dose-dependently stimulates both chemotaxis and cell proliferation. PDGF and TGF-beta appear to exert distinct effects on the two parameters, the former involved in stimulating cell migration and the latter in inhibiting cell proliferation. It is concluded that the different growth factors present in activated PRP can specifically contribute to the main processes of tissue regeneration.

Response to aspirin and clopidogrel monitored with different platelet function methods

Laboratory non-response to aspirin or clopidogrel is defined as an inability to cause in vitro detectable platelet function inhibition. It would be beneficial to monitor response to aspirin or clopidogrel with widely available and routinely used platelet function methods, like the platelet function analyzer (PFA-100®) or the fully automated coagulation analyzer BCT®. The aim of this study was to assess the potential of the coagulation analyzer BCT® and the platelet function analyzer PFA-100® in monitoring the response of aspirin and clopidogrel. A group of 125 consecutive patients with arterial occlusive disease treated either with aspirin 100 mg/day (82 patients) or clopidogrel 75 mg/day (43 patients) as only antiplatelet drug were investigated. For the first time platelet-enriched plasma (PRP), not adjusted to a fixed predetermined concentration of platelets, was used for aggregation studies and the effect of clopidogrel alone without combination of aspirin treatment on platelet function was investigated. Response to aspirin was observed in 85% (70/82) of patients using PFA-100®, while performing the arachidonic acid-induced aggregation on the BCT showed an inhibitory effect to aspirin in 91% (75/82) of patients. Non-response to aspirin was assessed with both platelet function methods in 7% (6/82) of patients. Clopidogrel response was observed in 58% (25/43) of patients when performing ADP-induced aggregation on the BCT. On the PFA-100® the antiplatelet effect of clopidogrel could not be detected. In conclusion, measurement of platelet aggregation on the BCT using native platelet-enriched plasma allows the quantification of individual inhibitory effects to aspirin as well as to clopidogrel, while the PFA-100® seems only suitable to investigate the degree of platelet inhibition induced by aspirin but not by clopidogrel.

Composition and characteristics of an autologous thrombocyte gel

Background The purpose of the current study was to characterize and compare an autologous thrombocyte gel containing several blood components with a commercially available glue. Materials and methods Twenty-five volunteers had blood drawn, and lab values, characteristics of the platelet-enriched plasma (PRP), thrombocyte aggregation, electron microscopic examinations, and the breaking strength were determined and compared to a commercial glue. Results Overall 65% of the total thrombocytes could be isolated from the volunteers and an enrichment of 300% with an autotransfusion device could be achieved. Thrombocyte aggregation as a marker for thrombocyte function decreased from 92% in patients to 71% in the PRP. The autologous glue demonstrated a significant reduced breaking strength (0,76 N/cm 3) compared to the commercial glue (7.42 N/cm 2), P < 0.05. The decrease in breaking strength could be correlated with the thrombocyte concentration, P < 0.05. Conclusions In the present study we have shown that an autologous platelet-enriched plasma cannot be used as a glue in the common sense to seal stitches or prosthesis. Platelet gels, however, have a high concentration of platelets that release the bioactive proteins and growth factors are necessary to initiate and accelerate tissue repair and enhance dermal and epidermal regeneration. To evaluate the possible clinical implication prospective, randomized studies should be performed to examine the effect of autologous plasma platelet-enriched plasma on wound healing.

Neonatal transfusion medicine: The use of blood, plasma, oxygen-carrying solutions, and adjunctive therapies in foals

The need for usage of blood, plasma, or blood substitutes arises not infrequently in equine practice. There are multiple conditions common to foals in the neonatal period that may result in a requirement for blood transfusion or augmentation of oxygen-carrying capacity, and the recognition and management of these problems is discussed. Administering plasma or other products in the face of immunologic insufficiency because of failure of passive transfer is revisited, and thrombocytopenia in newborn foals is discussed, as an indication for supplementing platelets with platelet-enriched plasma.

Antithrombotic activity of N,N-dichlorotaurine on mouse model of thrombosis in vivo.

Intravenous injection of chloramine derivatives of amino acids and taurine reduced the mortality rate in mice with thrombosis induced by intravenous injection of ADP or collagen-epinephrine mixture. Intravenous injection of N,N-dichlorotaurine caused 50% inhibition of platelet aggregation induced by ADP and measured in the platelet-enriched plasma in vitro. The antithrombotic effect of chloramine derivatives of amino acids and taurine is related to their ability to suppress functional activity of platelets.

Fibrin-depolymerization activity and the antiplatelet effect of small cyclic and linear proline-containing peptides

In our study of the effect of proline-containing linear di- and tri-peptides (Pro-Gly, Pro-Gly-Pro) and cyclic peptide cPro-Gly in vitro, we have found that they show depolymerizing activity towards the nonstabilized form of fibrin in the presence and in the absence of sigma-aminocapronic acid, an inhibitor of enzymatic fibrinolysis. The peptides have an inhibitory effect on platelet aggregation in platelet-enriched blood plasma, when the process is induced by ADP, they also diminish the activity of factor XIIIa in blood plasma.

Inhibition of platelet aggregability by losartan in essential hypertension

Most clinical events associated with hypertension have a thrombotic component. Losartan is a selective, competitive antagonist of the thromboxane A 2 receptor in experiments performed in isolated vascular strips and in human and rat platelet-enriched plasma. In this study, we investigated for the first time whether losartan at therapeutic doses has an effect on platelet aggregability and indexes of fibrinolysis in essential hypertensive subjects. Changes in the dose-response curve to platelet aggregation induced by the thrombin receptor-activating peptide SFLRRN-NH 2 were determined in 9 patients (56% men, 72% white; mean age 52.8 years) with stage I or II essential hypertension and in 9 untreated healthy volunteers. After a 4-week washout period, hypertensive subjects received 2 weeks of placebo followed by 4 weeks of losartan 50 mg/day. Both subjects and end points were blinded for treatment assignment. In addition, plasminogen activator inhibitor type 1 antigen and von Willebrand antigen were studied in all patients and controls. Four weeks of losartan produced a statistically significant (p <0.05) increase in the concentration of SFLRRN-NH 2 required to induce a half-maximal response in platelet aggregation extent and rate 4 weeks after initiation of treatment. The decrease in platelet aggregability was independent of blood pressure control and the effects of gender and age. Losartan had no effect on plasma concentrations of plasminogen activator inhibitor-1 and von Willebrand factor in hypertensive subjects. These data demonstrate for the first time a novel antiplatelet effect of losartan at therapeutic doses, which was independent of changes in blood pressure, plasma markers of fibrinolytic activity, and endothelial perturbation.

Biocompatibility of Polysulfone II. Platelet Adhesion and CHO Cell Growth

Experimental results on the platelet adhesion, and CHO cell adhesion and growth onto nonionic surfactant which is composed of a long alkyl chain (n = 12-18) as the hydrophobic part, and a polyethyleneoxide (PEO) segment (n = 10-23) as the hydrophilic part coated and air-plasma treated PSf surfaces are presented in terms of PEOs functionality and surface wettability to improved blood- and cell-compatibility of polysulfone. Platelet adhesion experiments on surface treated PSf films were carried out with platelet enriched plasma (PRP) in the parallel flow chamber in vitro. Number and morphology of adhered platelets were observed by scanning electron microscope. The number of adhered platelets on nonionic surfactant coated surfaces decreased significantly compared to the control. Also, the adhesion of platelets on to PSf substrate decreased with increasing coating concentration of nonionic surfactant. In the dry air-plasma exposed PSf sample, the adhesion of platelets decreased independently of plasma exposure time, and significant diminution of platelet adhesion was observed below about 40 degrees of the contact angle. It is believed that less platelet adhesion is preceded by less protein adsorption due to hydrophobic dehydration interaction. In Chinese hamster ovary (CHO) cell, adhesion and growth cells grew better on the air-plasma treated PSf surfaces. From these results, it can be proposed that surface wettability of PSf is very important for cell adhesion and growth.

Effect of triofen on the aggregating properties of platelets

The problem of prevention of the thrombohemorrhagic syndrome is a very acute one in contemporary clinical medicine. Disturbances of the aggregating properties of platelets, expressed primarily as slowing of aggregation and inability of the cells to undergo reversible interaction, are directly related to the formation of this syndrome. Irreversible aggregation is evidence of gross disturbances of platelet function and is a factor predisposing to latent intravascular thrombosis and microcirculatory disorders [3]. Acetylsalicylic acid (aspirin), dipyridamole (Curantyl or Persantin), salicylates, heparin, preparations of the pyrazolone series, xanthins, and nicotinic acid have been used as antiaggregants in clinical practice [i]. Important disadvantages of all known antiaggregants are the low efficacy of most of them (Persantin, pyrazolones), the probability of an undesirable side effect, the impossibility of parenteral administration of most of them (aspirin). Hence the necessity for a search for new and improved antiaggregants. The aim of the present investigation was to study the antiaggregant properties of the drug Triofen (trade mark No. 78660), known as a biological stimulator. EXPERIMENTAL METHOD The investigation was based on a study on the effect of Triofen in vitro on aggregation of platelets from 12 normal blood donors and 20 patients with acute suppurative-destructive diseases of the lungs and pleura, in whom hyperaggregation of the erythrocytes was observed [2]. Platelet aggregation was studied by Born's method [4] on a photoelectrometric aggreograph specially designed for the purpose. The measuring part of the aggreograph consisted of an FEK-56M photoelectric colorimeter, the recording part of an LKD-4 laboratory compensator. Platelet-enriched plasma was mixed in the cuvette with a working edge of 3 mm by means of a fluorine plastic mixer, rotating at a speed of 700 rpm by means of an EM-120 electric motor. Platelet-enriche

Direct and indirect antiaggregating action of sodium hypochlorite on platelet-enriched blood plasma

Direct and indirect antiaggregating action of sodium hypochlorite on platelet-enriched blood plasma

Arteriovenous difference in levels of vascular and platelet factors of hemostasis

The authors study arteriovenous differences that lie at the basis of the mechanism of thrombus formation in arteries and veins. The experiments were carried out on rats. ADP-induced platelet aggregation, the malonic dialdehyde concentration, and the cAMP concentration, the last by radioimmunoassay, were determined in the platelet-enriched plasma. The antiaggregation activity of the aorta and posterior vena cava was estimated by determination of the antiaggregation properties and cAMP level in the vessel walls by radioimmunoassay. It is concluded that great importance in the mechanism of white thrombus formation must be ascribed to disturbance of the vascular-platelet component of the hemostasis system, and in the mechanism of formation of the red thrombus - to disturbance of the coagulation component.