Form Of Platelet-rich Plasma Research Articles

An In Vitro Study on the Application of Silver-Doped Platelet-Rich Plasma in the Prevention of Post-Implant-Associated Infections.

Implant therapy is a common treatment option in dentistry and orthopedics, but its application is often associated with an increased risk of microbial contamination of the implant surfaces that cause bone tissue impairment. This study aims to develop two silver-enriched platelet-rich plasma (PRP) multifunctional scaffolds active at the same time in preventing implant-associated infections and stimulating bone regeneration. Commercial silver lactate (L) and newly synthesized silver deoxycholate:β-Cyclodextrin (B), were studied in vitro. Initially, the antimicrobial activity of the two silver soluble forms and the PRP enriched with the two silver forms has been studied on microbial planktonic cells. At the same time, the biocompatibility of silver-enriched PRPs has been assessed by an MTT test on human primary osteoblasts (hOBs). Afterwards, an investigation was conducted to evaluate the activity of selected concentrations and forms of silver-enriched PRPs in inhibiting microbial biofilm formation and stimulating hOB differentiation. PRP-L (0.3 µg/mm2) and PRP-B (0.2 µg/mm2) counteract Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans planktonic cell growth and biofilm formation, preserving hOB viability without interfering with their differentiation capability. Overall, the results obtained suggest that L- and B-enriched PRPs represent a promising preventive strategy against biofilm-related implant infections and demonstrate a new silver formulation that, together with increasing fibrin binding protecting silver in truncated cone-shaped cyclic oligosaccharides, achieved comparable inhibitory results on prokaryotic cells at a lower concentration.

Beneficial effects of intraovarian injection of platelet-rich plasma in women with poor ovarian response.

Infertility can result from a diminished ovarian reserve, but a potential remedy exists in the form of platelet-rich plasma (PRP) administration. This treatment involves both biological factors and tissue trauma mechanisms, which stimulate folliculogenesis, making it a promising and effective strategy. We assessed the impact of direct PRP injections into the ovaries on the fertility outcomes of women classified as poor responders. A quasi-experimental study was conducted from April 2021 to December 2022, focusing on patients classified as POSEIDON grade 3 or 4. PRP injections were administered into both ovaries. After 3 months, data were collected on anti-Müllerian hormone (AMH) level, follicle-stimulating hormone (FSH) level, and the numbers of oocytes, mature oocytes, and good-quality embryos following ovarian stimulation. We then compared the data from before and after PRP injection. This study included 50 women, with a mean of 39 years (interquartile range [IQR], 35 to 43) and 4 years (IQR, 2 to 6) for age and infertility duration, respectively. FSH levels decreased after treatment, while AMH levels and the numbers of oocytes, metaphase II oocytes, and high-quality embryos increased. However, only the increase in high-quality embryos was significant. The pregnancy and spontaneous pregnancy rates were 20% and 14%, respectively. Notably, women with secondary infertility exhibited a significantly higher pregnancy rate than those with primary infertility. Ample evidence suggests that PRP can enhance ovarian function. However, further studies are needed to identify the appropriate candidates for this procedure, establish the optimal PRP preparation method, and standardize the procedure for its adjuvant use in assisted reproductive technology cycles.

Evaluation of different platelet-rich plasma protocols for use in the equine reproductive clinic

Platelet-rich plasma (PRP) is a biological product used in equine regenerative medicine., Several methods and protocols for obtaining the different forms of PRP exist, depending on the application. In reproductive medicine, there is a need to classify the product according to the number of leukocytes, erythrocytes, and platelets present in PRP. This evaluation allows the classification of pure plasma rich in platelets (P-PRP) or plasma rich in leukocytes and platelets (L-PRP) and not just with the generic name of PRP. The objective of this study was to evaluate the concentration of platelets, erythrocytes, leukocytes, and bacterial load present in PRP, produced by two protocols already used in the equine reproductive clinic and two new protocols that aimed for greater efficiency/simplicity in the separation process. Ten horses of different breeds were selected, and from each one, five total blood samples were collected by venipuncture: one for the complete blood count and four protocols to produce PRP using different protocols (P1, P2, P3, and P4). In P1 and P2, the blood was collected in a vacutainer (4 mL glass tubes) with sodium citrate at 3.2%. P3 and P4 blood collections were in an open system into 50 mL conical plastic tubes using sodium citrate at 3.2% and citrate-phosphate-dextrose adenine (CPDA-1) at 14%, respectively. P1 used 120g/ 10 min centrifugation, and P2 performed two centrifugations, one at 120g / 10min and the other at 240g / 10 min. In both protocols, P3 and P4 used two centrifugations (215g / 10 min and 863g / 10 min). Analysis of blood components and bacterial growth was performed. Protocols were considered independent factors, and platelet, erythrocyte, and leukocyte concentrations as dependent variables. Platelet concentration was analyzed with ANOVA and t-test; erythrocytes and leukocytes concentration with Kruskal Wallis and Mann Whitney test. Platelet concentration was higher in P3 and P4 than in P1 (P < 0.0009) and equal to P2. P1 presented a lower concentration of erythrocytes than P2, P3, and P4 (P = 0.0014). Leukocytes were observed in all groups. However, P1 had a lower number of leukocytes than P3 and P4 (P = 0.0120) but showed no difference from P2. All groups were identified as being P-PRP and without bacterial contamination. The characterization of quantities and proportions of the blood cells after each protocol will lead to a specific clinical use (intrauterine platelets will aid in persistent post-covering endometritis), since the presence of certain blood cells, can generate different results in tissue proliferation, differentiation, and immunity. Therefore, the P3 and P4 protocols may have advantages in treating reproductive diseases, as the larger volumes make the procedure faster and simpler.

Swiss Medical Devices for Autologous Regenerative Medicine: From Innovation to Clinical Validation

Regenerative medicine, based on the use of autologous tissues and embryonic, stem or differentiated cells, is gaining growing interest. However, their preparation, in a manner compliant with good practices and health regulations, is a technical challenge. The aim of this manuscript is to present the design of reliable CE marked medical devices for the preparation of standardized platelet-rich plasma (PRP) and other autologous biologics intended for therapeutic uses. There are numerous PRP isolation processes. Depending on the methodology used, PRP composition varies greatly in terms of platelet concentration, platelet quality, and level of contamination with red and white blood cells. This variability in PRP composition might affect the clinical outcomes. The devices presented here are based on a specific technology, patented all over the world, that allows the precise separation of blood components as a function of their density using thixotropic separator gels in closed systems. This allows the preparation, in an automated manner, of leukocyte poor PRP with a standardized composition. Production of different forms of PRP is a clinical asset to suit various therapeutic needs. Therefore, we are offering solutions to prepare PRP either in liquid or gel form, and PRP combined with hyaluronic acid. These biologics have been successfully used in many different therapeutic domains, resulting in more than 150 published clinical studies. We also developed the CuteCell technology platform for cell culture expansion for further autologous cell therapies. This technology enables the safe and rapid in vitro expansion of cells intended for therapeutic use in good manufacturing practices (GMP) and autologous conditions, using blood-derived products as culture media supplementation. We summarize in this article our 20 years’ experience of research and development for the design of PRP devices and, more recently, for PRP combined with hyaluronic acid.

Role of Masson’s trichrome stain in evaluating the effect of platelet-rich plasma on collagenesis after induction of thermal burn in adult male albino rats

Background Burns are a global health problem, accounting for about 180 000 deaths annually especially in low- and middle-income countries. Many reports have concentrated on the role of platelet-rich plasma (PRP) in the treatment of soft tissue burn lesions. Aim This work aimed to study the role of Masson’s trichrome stain in evaluating the effect of PRP on induced thermal burn in adult male albino rats. Materials and methods In all, 50 adult male albino rats were divided into blood donor group (10 rats), control group (10 rats), and experimental group (30 rats). The experimental group was further subdivided into subgroups A, B, and C. For the experimental group, the rats were anesthetized and exposed to thermal burn. Subgroup A were subjected to contact thermal burn and left without treatment. Subgroup B were subcutaneously injected with 0.3 ml of autologous PRP. In subgroup C autologous topical PRP was applied. Skin specimens were obtained and stained by Masson’s trichrome for histological evaluation at days 1, 7, 14, and 28 after burn induction. Results The subgroups that were treated by PRP were found with better collagen organization and earlier restoration of normal histological features of skin tissue. Conclusion Application of different forms of PRP (injectable and topical) helps healing of burn wounds.

Evaluation of platelet-rich plasma vs. platelet lysate: VEGF and PDGF concentration, stability, and shelf life

Cell-free biologicals are a novel method of treating clinical conditions which involve chronic inflammation such as tendonitis and osteoarthritis. Standard approaches for addressing such conditions involve steroids and powerful pain killers, which predispose patients to unfavorable clinical outcomes. Cell-free biologicals like platelet-rich plasma (PRP) and platelet lysate (PL) derived from blood provide a reliable approach to treat chronic inflammation. aPRP is the activated form of PRP and is assumed to contained higher concentration of cytokines. These blood derivatives are safe and can be administered with ease over long periods. Although this approach is widely popular among physicians, it requires scientific standardization of its growth factors and a complete analysis of its shelf life and stability. In this study, we compared platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) in PRP, activated PRP (aPRP), and PL. We analyzed the shelf life at different storage temperature over three weeks. We hypothesized that PL would contain higher concentrations of growth factors than PRP and that different storage temperatures for PL would diminish cytokine expression. Our results demonstrated PL had the highest concentrations of both cytokines, with concentrations slightly diminishing at-80C. aPRP and PRP demonstrated lower concentrations of PDGF and VEGF than PL.

Effect of collagen-chitosan hydrogel formula combined with platelet-rich plasma (A study of ph, viscocity, and swelling test)

Platelet-rich plasma (PRP) contains growth factors that speed up a healing process. The liquid form of PRP is difficult to be applied, so it needs material as a carrier of collagen. Collagen can be used as carrier materials and capable to activate growth factors and increase the concentration of the PRP to become a gel. Collagen often losses its shape and size due to degradation when exposed to body fluids. In the selection of materials, collagen can synthesize with chitosan. Collagen-chitosan hydrogel has potential as scaffold. Many formulations for proper hydrogel applied in the oral cavity need to pay more attention to several conditions, such as a neutral pH, high viscosity and ideal swelling. The aims of this study was to examine the influence of various formulations of collagenchitosan hydrogel PRPagainst pH, viscosity, and swelling. The study samples consisted of 25 collagen-chitosanhydrogel formulations. The samples were divided into five groups: 100/0; 75/25; 50/50; 25/75; 0/100. The first stage of the test was pH, viscosity and swelling measurement of the collagen-chitosan hydrogel to determine which ones matched the criteria. Collagen-chitosan hydrogel formulations were added with PRP with a ratio of 1:1. The second stage was to measure the pH, viscosity, and swelling measurement to see the results of the physical parameters of the hydrogel after mixed with PRP. The observation data were analyzed by t-test for pH and viscosity, while twoway ANOVA and post hoc LSD for swelling test. The results showed that collagen-chitosan hydrogel formulations of 25/75 and 0/100 met the criteria of pH, viscosity, and swelling. The pH of both groups showed no significant difference (p&gt;0.05), but the viscosity and swelling variables showed significant difference (p&lt;0.05). To conclude, collagen-chitosan hydrogel formulations mixed with PRP had no effect on pH, but had an effect on viscosity and swelling test. The collagen-chitosan hydrogel formulations mixed with PRP which matched the criteria were 25/75 and 0/100.

Platelet-Rich Plasma: Optimal Use in Surgical Wounds

Activated platelets release a rich broth of growth factors involved in wound healing. One way to deliver activated platelets to wounds is in the form of platelet-rich plasma (PRP) harvested by centrifuging the patient's venous blood after activating the platelets with collagen or calcium chloride and/or autologous thrombin, then delicately removing the supernatant, called platelet-poor plasma (PPP). Platelet-rich plasma is usually injected into the lesion and/or applied topically, then sealed in or over the wound using a moisture-retentive dressing. Platelet-rich plasma (often with PPP) has been applied at different times, depths, and frequencies to chronic and acute wounds using various PRP doses and vehicles to achieve widely differing results. Meta-analyses have reported that PRP improved healing rates of open diabetic foot ulcers and venous ulcers and may reduce pain and surgical site infection (SSI) incidence in open and closed acute surgical wounds. However, inconsistency in study methods and outcome measures limited consistency of pain and SSI results. No consistent effect on healing or deep SSI rates was reported as a result of adding 1 intraoperative dose of PRP in the surgical site before closing elective foot and ankle surgery incisions of 250 patients as compared with 250 similar patients receiving the same procedure without PRP. After decades of research, ideal parameters of PRP delivery and use on each type of wound remain unclear for improving SSI, acute wound pain, and healing outcomes. This installment of the Evidence Corner reviews 2 surgical studies that may provide clues about optimal PRP use. One triple-blind randomized clinical trial (RCT) focused on irrigation of freshly closed carpal ligament surgical incisions with PRP as compared with PPP. Another non-blind RCT explored the effect of injecting PRP into open pilonidal sinus excisions 4 days and 12 days after surgery.

In Vitro Osteogenic Potential of Freeze-Dried Homologous Platelet-Rich Plasma

Introduction: Platelet-rich plasma (PRP) is paid attention for regenerative therapy because it clinically improves neoangiogenesis and periodontal regeneration. PRP can be made in form of homologous PRP (HPRP) from healthy, screened, and habitual blood donors and freeze-dried to increase stored time of HPRP and maintain growth factors. The purpose of this study is to evaluate freeze-dried homologous platelet-rich plasma (FD HPRP) on osteogenesis. Material and Methods: HPRP was taken from the blood bank and then a freeze-drying and γ-radiation process was carried out with doses of 20 and 25 KGy, respectively, for the sterilization. Blood was collected as much as 10 mL and then centrifuged at 700 rpm for 3 minutes to produce injectable platelet-rich fibrin (iPRF) as a positive control. Cell line MG63 were cultured to confluent, and then treated with FD HPRP 20 kGy, FD HPRP 25 kGy, iPRF, and one group non treated as a negative control. Osteocytes were determined based on morphology after hematoxylin staining to see the differentiation process. The data were analyzed using one-way analysis of variance (ANOVA). Results: There was a significant difference in the number of osteocytes between FD HPRP and negative control (P < 0.05). The number of osteocytes FD HPRP 25 was higher than FD HPRP 20. Conclusion: The present results indicate that FD HPRP could support the bone regeneration and used without any preparation like fresh PRP.

Intra-articular injection with Autologous Conditioned Plasma does not lead to a clinically relevant improvement of knee osteoarthritis: a prospective case series of 140 patients with 1-year follow-up

Background and purpose — Platelet-rich plasma (PRP) is broadly used in the treatment of knee osteoarthritis, but clinical outcomes are highly variable. We evaluated the effectiveness of intra-articular injections with Autologous Conditioned Plasma (ACP), a commercially available form of platelet-rich plasma, in a tertiary referral center. Second, we aimed to identify which patient factors are associated with clinical outcome. Patients and methods — 140 patients (158 knees) with knee osteoarthritis (Kellgren and Lawrence grade 0–4) were treated with 3 intra-articular injections of ACP. The Knee Injury and Osteoarthritis Outcome Score (KOOS), pain (Numeric Rating Scale; NRS), and general health (EuroQol 5 Dimensions; EQ5D) were assessed at baseline and 3, 6, and 12 months’ follow-up. The effect of sex, age, BMI, Kellgren and Lawrence grade, history of knee trauma, and baseline KOOS on clinical outcome at 6 and 12 months was determined using linear regression. Results — Mean KOOS increased from 37 at baseline to 44 at 3 months, 45 at 6 months, and 43 at 12 months’ follow-up. Mean NRS-pain decreased from 6.2 at baseline to 5.3 at 3 months, 5.2 at 6 months, and 5.3 at 12 months. EQ5D did not change significantly. There were no predictors of clinical outcome. Interpretation — ACP does not lead to a clinically relevant improvement (exceeding the minimal clinically important difference) in patients suffering from knee osteoarthritis. None of the investigated factors predicts clinical outcome.

Tissue particularities and problems related to bone healing and fracture repair

Tissue particularities and problems related to bone healing and fracture repair

Effect of light-emitting diodes, platelet-rich plasma, and their combination on the activity of sheep tenocytes.

Healthy tendons play an important role in joint movements and subjected to a group of pathologies called tendinopathy due to multiple factors. Tendons have a slowly repairing process due to the low vascularity and cellularity. Treatment options aimed at potentiating the healing response and relieving symptoms. Phototherapy and platelet-rich plasma were novel treatment modalities in tendons based on photobiomodulation and growth factors during healing, and the results were encouraging suggesting calibrating treatment parameters. This study utilizes cell culture to explore the potential effect of light-emitting diode and/or growth factors in the form of platelet-rich plasma (PRP) on the activity of tenocytes isolated from sheep Achilles tendons by measuring the cell metabolism and cell mobility using cell viability and migration assays to proof safety and confirm activity. Results showed that sheep tenocyte-cultured groups treated with 5% platelet-rich plasma alone or combined with 4J/cm2 light-emitting diode have increased viability significantly when compared to control group after a 48h, while light-emitting diode treatment has not decreased cell migration significantly when compared with control. Result suggests that using platelet-rich plasma alone or combined with light-emitting diode might have potential to enhance healing response at the conditions applied. PRP could enhance proliferation while LED could enhance migration and proliferation. Further research is needed at longer durations.

PROSPECTS FOR THE DEVELOPMENT OF REGENERATIVE TECHNOLOGIES. CURRENT KNOWLEDGE OF PLATELET RICH PLASMA AND THE POSSIBILITY OF ITS APPLICATION IN TREATMENT OF COMPLICATED UROLOGICAL DESEASES

Currently, the most actual problem in daily work of a surgeon is to get satisfactory results of the surgery, and to decrease the quantity of different complications, such as: recurrence of diseases, inflammatory and infection damage of operating wounds.The most difficult for surgery treatment are urological diseases associated with the decrease of tissue vascularization, which leads to common fibrosis and the prevalence of soft tissue scarring, consequences of the radiation therapy.Impaired wound healing is usually associated with lack of adequate blood supply, decrease of regenerative properties, increase of pro-inflammatory mechanisms. Platelet rich plasma is able to produce a lot of different growth factors, which stimulate neoangiogenesis, cytokines and сhemokines secretion, initialization of inflammatory cascade. These features lead to activation of regenerative mechanisms and growth of new blood vessels. In the present time, several forms of platelet rich plasma with different biological activity have been studied. The methods of its preparation and activation have been described. In this work the modern information of platelet rich plasma will be described in details.

Enhanced Sternal Healing Through Platelet-Rich Plasma and Biodegradable Gelatin Hydrogel.

Platelet-rich plasma (PRP) contains numerous growth factors and promotes bone fracture healing. The aim of this study was to evaluate the effectiveness of the controlled release of PRP from biodegradable gelatin hydrogel for promoting healing in a rabbit ischemic sternal model. PRP was prepared from the whole blood of a Japanese white rabbit. Sixteen rabbits were randomized into four groups (each n = 4) and all underwent median sternotomy and bilateral internal thoracic artery removal. Before the sternum was closed, the following solutions were applied between the sternum incisions in three of the groups: 30 mg of gelatin hydrogel incorporating 300 μL of phosphate-buffered saline, 300 μL of a solution form of PRP, or 30 mg of gelatin hydrogel incorporating 300 μL of PRP (PRP + Gel). The fourth group acted as a control. Sternal healing was evaluated by histology and microcomputed tomography 7 days after the intervention. The PRP + Gel group showed a significantly higher proportion of fibrosis within the fracture area (an indicator of sternal healing) than the other groups and a significantly higher mean intensity of osteocalcin. These results indicate that the controlled release of PRP from locally applied gelatin hydrogel was markedly effective in enhancing sternal healing in the early postoperative period. This novel therapy could potentially help prevent complications, such as deep sternal wound infection and could result in early postoperative ambulation after median sternotomy.

A Method for the Activation of Platelet-Rich Plasma via Bead Mill Homogenizer for Mesenchymal Stem Cell Culture.

Activated platelet-rich plasma (PRP) has been studied as a replacement for fetal bovine serum (FBS) in stem cell culture. However, current methods are time-consuming or require addition of exogenous substances to activate PRP, which have disadvantages in clinical applications. In this study, we developed a new method for PRP activation using a bead mill homogenizer and compared it with previous methods of PRP activation. PRP was prepared via a two-step centrifugation process and activated via calcium (Ca-PRP), freeze-thaw cycles (FT-PRP), or bead mill homogenizer processing (BM-PRP). Quantification of growth factors in PRP revealed that all forms of activated PRP released higher levels of platelet-derived growth factor-AB and transforming growth factor-β1 than those in platelet-poor plasma; however, BM-PRP resulted in significantly higher levels of growth factors than those from Ca-PRP and FT-PRP. Next, we analyzed the ability of the various forms of PRP to stimulate proliferation, migration, and differentiation of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). Our results showed that BM-PRP significantly increased proliferation and migration rates of UCB-MSCs while maintaining the phenotypical properties and stem cell abilities of MSCs. Therefore, the developed method could be suitable for PRP activation, and the BM-activated PRP could be an adequate replacement for FBS in stem cell culture.

The effect of intradermal administration of inactive platelet-rich plasma on flap viability in rats.

To evaluate the effect of inactive form of platelet rich plasma (PRP) on the flap viability. Thirty six rats were used. Rats were divided into six groups then 9x3 cm random pattern skin flaps were elevated from dorsum of all rats. For precluding vascularization from the base, a silicone layer was placed under the flap in groups 2(only flap+silicone), 4(saline+silicone) and 6(PRP+silicone). In groups 1(only flap), 2(only flap+silicone) nothing was done except flap surgery. In groups 3(saline) and 4(saline+silicone), saline was applied intradermally , in groups 5(PRP) and 6(PRP+silicone), inactive form of PRP which obtained from different 16 rats was applied intradermally, into certain points of flaps immediately after surgery. After 7 days flap necrosis ratio was measured in all groups. Mean necrosis rate in group 5(PRP) (16.05%) was statistically significantly lower than group 1(only flap) (31,93%) and group 3(saline) (30,43%) (p<0.001). Mean necrosis rate in group 6(PRP+silicone) (36.37%) was statistically significantly lower than group 2(only flap+silicone) (47.93%) and group 4(saline+silicone) (45.65%) (p<0.001). Intradermal inactive platelet rich plasma administration decreases flap necrosis so for skin application.

Liquid and Gel Platelet Rich Plasma as Skin Healing Adjuvant

Background: In recent decades, many researches have been conducted on processes involved in tissue repairing, mainly in the development of resources and technology designed to improve the wound healing progress. Platelet rich plasma (PRP) derived from autologous blood is defined as a plasma volume with platelet concentration higher than physiological level. It is an autogenous and low cost source of growth factors, which are essential for tissue regeneration due to their angiogenic, mitogenic, and chemotactic properties. The aim of this study was evaluate two forms of PRP- liquid and gel - regarding their capacity to influence quality and repair time of standardized skin injuries.Materials, Methods &amp; Results: New Zealand healthy rabbits were distributed in three groups (n = 6): control group (CG), liquid platelet rich plasma group (LIQPRP), and gel platelet rich plasma group (GELPRP). Acute skin lesions were inducted in two areas approximately 2 cm close to scapular edge and depth including epidermis, dermis, and hypodermis to external muscular fascia. Animals received treatment according to each group. Injuries were measured with digital pachymeter in two directions: longer length (l) and longer width (w), every two days. Areas and healing rates were calculated. Microscopic analysis samples were collected on days seven and 14 and evaluated through hematoxylin and eosin staining (HE) for global tissue examination, and through Masson’s trichrome (MT) to collagen fibers present within the interstice. These analyzes considered: angiogenesis, inflammation infiltrated and collagen fibers quantity. Immunohistochemistry with anti-Ki-67 antibody was utilized for proliferative profile assessment. Kruskal-Wallis’ non-parametric tests of independent samples was performed for comparison of values obtained through platelet count, referring to evaluation of platelet increase on treatments. Scar contraction rate (CR) was evaluated through Shapiro-Wilk’s normality test, and then submitted to mixed models test. Results obtained by histopathological and immunohistochemistry were also evaluated by Shapiro-Wilk’s normality test (for all tests a 5% level of significance was considered). Platelet concentration achieved with liquid PRP was 8.64 and gel PRP reached 5.62 times higher than physiological values. Platelet increase mean for both groups was 7.95. No statistical significance was observed between groups. No side-effects or adverse reactions related to PRP usage were observed while study was conducted.Discussion: In the present study, there was a need to raise platelet poor plasma volume in order to obtain autogenous thrombin required for gel PRP. After this modification, a stable and reasonable platelet concentration gel was produced. However, this form of PRP application requires more time for sample preparation, increasing the production cost. Furthermore, injection of liquid PRP directly in the wound site activates platelets by generated substances due to needle perforation, and mainly due to tissue trauma generated at the lesion site. Relating to the therapies administered, gel PRP was considered more manageable, since 3D structure could easily adapt to wound site after simply deposition of it. Liquid PRP was administered with needle and syringe, which required the surgeon to be more careful and perform a slow injection in order to avoid any spill and loss of material. Furthermore, histopathological analysis did not point any clot traces formed by gel PRP dehydration, although it is not possible to ensure that the clot was eliminated, reabsorbed, or even removed by the animal. By this protocol, a stable and reasonable platelet concentration gel was produced. Further studies are encouraged as well as employment of alternative diagnostic tools, in order to better understand found results.

Does Platelet-Rich Plasma Increase Tendon Metabolism?

Acute and overuse tendon disorders are frequently observed in the middle-aged active population. Tendon overuse injuries are currently designated as "tendinopathy". Histopathological studies have shown that chronic tendinopathy is frequently characterised by degenerative changes, such as decreased organisation of collagen, altered cell distribution and neovascularisation. In the recent years, scientific research and technology in the field of regenerative medicine has provided a new perspectives on managing chronic tendinopathy. An initiation of tissue healing can be attempted by local delivery of growth factors. Nowadays, platelet-rich plasma (PRP) is a commonly applied approach to achieve this. Platelet degranulation leads to a release of various growth factors and cytokines. There is a classification system to define the different forms of PRP. In the past decade, a number of studies have been published on the effects of PRP in different basic science studies. These studies suggest that PRP modulates some aspects of tendon metabolic activity. This is one of the reasons why PRP is increasingly used by many clinicians as treatment option for tendinopathy in daily clinical practice. There is, however, evidence from the literature that it does not lead to improved outcome on imaging findings and on patient-reported outcomes. This questions the role of PRP injections as regular treatment for tendinopathy. Moreover, it results in a broader discussion on the required effects that need to occur for tendon healing and symptom relieve.

The Basic Science of Platelet-rich Plasma (PRP)

Platelet-rich plasma (PRP) has been advocated for the biological augmentation of tissue healing and regeneration through the local introduction of increased levels (above baseline) of platelets and their associated bioactive molecules. In theory, the increased levels of autologous growth factors and secretory proteins provided by the concentrated platelets may enhance the wound healing process, especially in degenerative tissues or biologically compromised individuals. Although PRP has been increasingly utilized in the treatment of a variety of sports-related injuries, improvements in healing and clinical outcomes have not been universally reported. One reason for this may be the fact that all PRP preparations are not the same. Variations in the volume of whole blood taken, the platelet recovery efficacy, the final volume of plasma in which the platelets are suspended, and the presence or absence of white blood cells, and the addition of exogenous thrombin to activate the platelets or calcium chloride to induce fibrin formation, can all affect the character and potential efficacy of the final PRP product. This article will review the basic principles involved in creating PRP and examine the potential basic scientific significance of the individual blood components contained in the various forms of PRP currently used in sports medicine.

Platelet-Rich Plasma Exerts Antinociceptive Activity by a Peripheral Endocannabinoid-Related Mechanism

In regenerative medicine, platelet by-products containing factors physiologically involved in wound healing, have been successfully used in the form of platelet-rich plasma (PRP) for the topical therapy of various clinical conditions since it produces an improvement in tissue repair as well as analgesic effects. Measurement of endocannabinoids and related compounds in PRP revealed the presence of a significant amount of anandamide, 2-arachidonoylglycerol, palmitoylethanolamide, and oleoylethanolamide. Investigation of the activity of PRP on the keratinocyte cell line NCTC2544 in physiological and inflammatory conditions showed that, under inflammatory conditions, PRP induced in a statistically significant manner the production of these compounds by the cells suggesting that PRP might induce the production of these analgesic mediators particularly in the physiologically inflamed wounded tissue. Studies in a mouse model of acute inflammatory pain induced by formalin injection demonstrated a potent antinociceptive effect against both early and late nocifensive responses. This effect was observed following intrapaw injection of (1) total PRP; (2) lipids extracted from PRP; and (3) an endocannabinoid-enriched lipid fraction of PRP. In all conditions, antagonists of endocannabinoid CB1 and CB2 receptors, injected in the paw, abrogated the antinociceptive effects strongly suggesting for this preparation a peripheral mechanism of action. In conclusion, we showed that PRP and PRP lipid extract exert a potent antinociceptive activity linked, at least in part, to their endocannabinoids and related compound content, and to their capability of elevating the levels of these lipid mediators in cells.