Leukocyte- And Platelet-rich Plasma Research Articles

Efficacy of Platelet-Rich Plasma Intra-articular Injections in Hip and Knee Osteoarthritis.

Osteoarthritis (OA) is a chronic degenerative disorder that causes significant pain and functional limitations. Platelet-rich plasma (PRP) therapy has gained considerable attention in recent years in the treatment of musculoskeletal injuries. In this narrative review, we aim to investigate the role of intra-articular PRP injections in the treatment of knee and hip OA. The review also discusses different classifications of PRP based on composition. Furthermore, this narrative review also identified various limitations of PRP therapy in OA. PRP is classified into different types based on cell content and fibrin architecture, including pure platelet-rich plasma (P-PRP), leukocyte- and platelet-rich plasma (L-PRP),pure platelet-rich fibrin (P-PRF), and leukocyte- andplatelet-rich fibrin (L-PRF).Various clinical trials have shown that PRP is an effective option for the treatment of knee and hip OA. However, the superiority of PRP over hyaluronic acid has been reported inconsistently. This variability can be attributed to PRP preparation techniques. The safety profiles of PRP are generally favorable and the adverse effects are generally mild in nature. Although there is sufficient evidence in support of PRP in the treatment of OA, the long-term effects of PRP have not been reported. Further studies should focus on longer follow-up periods to identify the efficacy and safety of PRP in treating knee OA. There is also a need for standardization of PRP preparations in OA management.

Leukocyte and Platelet-Rich Plasma (L-PRP) in Tendon Models: A Systematic Review and Meta-Analysis of in vivo/in vitro Studies.

To perform a systematic review on the application of leukocyte- and platelet-rich plasma (L-PRP) in tendon models by reviewing in vivo/in vitro studies. The searches were performed via electronic databases including PubMed, Embase, and Cochrane Library up to September 2022 using the following keywords: ((tenocytes OR tendon OR tendinitis OR tendinosis OR tendinopathy OR tendon injury) AND (platelet-rich plasma OR PRP OR autologous conditioned plasma OR leukocyte- and platelet-rich plasma OR L-PRP OR leukocyte-richplatelet-rich plasma Lr-PRP)). Only in vitro and in vivo studies that assessed the potential effects of L-PRP on tendons and/or tenocytes are included in this study. Description of PRP, study design and methods, outcomes measured, and results are extracted from the data. A total of 17 studies (8 in vitro studies and 9 in vivo studies) are included. Thirteen studies (76%) reported leukocyte concentrations of L-PRP. Four studies (24%) reported the commercial kits. In in vitro studies, L-PRP demonstrated increased cell proliferation, cell migration, collagen synthesis, accelerated inflammation, and catabolic response in the short term. In addition, most in vivo studies indicated increased collagen type I content. According to in vivo studies reporting data, L-PRP reduced inflammation response in 71.0% of studies, while it enhanced the histological quality of tendons in 67.0% of studies. All 3 studies reporting data found increased biomechanical properties with L-PRP treatment. Most evidence indicates that L-PRP has some potential effects on tendon healing compared to control. However, it appears that L-PRP works depending on the biological status of the damaged tendon. At an early stage, L-PRP may accelerate tendon healing, but at a later stage, it could be detrimental.

High-Throughput Proteomic Analysis of Human Dermal Fibroblast Response to Different Blood Derivatives: Autologous Topical Serum Derived from Plasma Rich in Growth Factors (PRGF) versus Leukocyte- and Platelet-Rich Plasma (L-PRP).

Platelet-rich plasma (PRP) is nowadays used in the treatment of different types of cutaneous lesions. However, different compositions can influence clinical outcomes. Among them, the inclusion of leukocytes is controversial. High-throughput proteomics techniques were used to analyze the proteins that are differentially expressed in human dermal fibroblasts (HDFs) after treatment for 24 h with two PRP types, autologous topical serum (Endoret serum—ES) derived from plasma rich in growth factors (PRGF) and leukocyte- and platelet-rich plasma (L-PRP). The identified proteins were then classified by both Gene Ontology and Ingenuity Pathway Analysis. The obtained results show that the compositions of ES and L-PRP differ in such a way that they induce different responses in HDFs. ES-treated HDFs overexpress growth factor-related proteins, leading to protein synthesis, cell proliferation and migration. By contrast, L-PRP treatment induces a response similar to that caused by proinflammatory molecules. These data could explain the contradictory clinical results obtained for the different types of PRP, especially with respect to their leukocyte contents.

Method to obtain PRP and L-PRP for the use in routine medical practice of orthopedic traumatologist

The paper presents the results of experimental study of two methods for blood processing to obtain platelet-rich plasma (PRP). Due to the widespread clinical use of platelet-rich plasma in orthopedics and traumatology, a differential approach to the use of PRP and leukocyte- and platelet-rich plasma (L-PRP) has become relevant. Most commercial kits for PRP preparation significantly increase the cost of treatment. In addition, the main attention is focused on the concentration of platelets in the final product and the marketing features of a particular kit (separating gel, tube shape, anticoagulant, activator, etc.). The role of leukocytes in the features of the regenerative effect of platelet-rich plasma stays out of focus. The blood of volunteers was processed in two different ways and the cellular composition of the obtained products was analyzed. Sample No. 1 was used as a control for the baseline blood cell composition. Sample No. 2 was centrifuged in a sterile plastic tube, platelet rich plasma was collected manually. Sample No. 3 was centrifuged in a sterile modified syringe, platelet rich plasma was collected using a closed technique by means of connectors together with a rich layer. The results of statistical analysis showed that there were obtained totally different biological products with different concentrations of platelets and leukocytes. The first sample (control) had platelet concentration of (228.69 ± 39.15) × 109/l and leukocyte concentration of (5.18 ± 1.32) × 109/l. In the second sample (tube + manual sampling), platelet concentration was (429.38 ± 79.92) × 109/l and leukocyte concentration — (0.85 ± 0.34) × 109/l. The third sample (syringe plunger + closed vacuum collection) had platelet concentration of (541.15 ± 85.49) × 109/l and leukocytes of (6.56±1.92)×109/l. The data are given without regard to –12.5% deviation on dilution with citrate dextrose. As the result of the work, orthopedic traumatologists can use the simplest non-commercial methods for obtaining PRP and L-PRP in their practice depending on nosology and clinical tasks.

Effects of leukocyte- and platelet-rich plasma on tendon disorders based on in vitro and in vivo studies (Review).

Tendon-related disorders are common musculoskeletal system disorders in clinical practice, accounting for 30-50% of all sports-related injuries, and they are difficult to treat due to the hypovascular structure of the tendons. Platelet-rich plasma (PRP), including pure PRP and leukocyte- and platelet-rich plasma (L-PRP), has been attracting increasing attention, as it may stimulate tissue regeneration through the release of growth factors and cytokines. The aim of the present review was to provide a summary of the effects of L-PRP on tendon disorders and the underlying mechanisms through a comprehensive examination of the published literature, including in vitro, animal and clinical studies. It has been demonstrated that L-PRP results in comparatively greater pain relief and improved function in patients suffering from tendon disorders. Furthermore, L-PRP may exert its effects through a diverse range of mechanisms, such as neovascularization, cell proliferation and differentiation of tendon/progenitor stem cells into tenocytes, as well as extracellular matrix reorganization by transforming type III to type I collagen fibers. It has also been indicated that the effects of leukocytes in L-PRP depend on the biological state of the injured tissue and its surrounding microenvironment. L-PRP is beneficial and promotes tendon healing at the early stage, whereas it is likely detrimental to the repair of tendon at a later stage because of the risk of excessive catabolic and inflammatory responses. Overall, the application of L-PRP in tendon disorders appears to be a promising field that is worthy of further research.

Plate-Rich Plasma and its Utility in Clinical Conditions: A Systematic Review

Platelet-rich plasma (PRP) is an autologous product derived from whole blood through the process of density gradient centrifugation which contains a concentrated form of a large number of platelets in a small volume of plasma. PRP has a higher concentration of growth factors than whole blood. These growth factors promote natural healing. PRP is becoming more popular as a treatment option for a broad spectrum of medical disorders. PRP has been studied but has received less attention. The objective of this literature review was to focus on the utility of PRP on various medical conditions and, to consolidate the available evidence on PRP for the practicing dermatological conditions.
 Keywords: Pure Platelet-Rich Plasma (P-PRP), Leukocyte-and Platelet-Rich Plasma (L-PRP), Red - Platelet-Rich Plasma (R-PRP), Injectable Platelet Rich Fibrin (i-PRF), Platelet-rich plasma (PRP), Platelet-poor plasma (PPP), Cytokines, Growth factors.

Efficacy of a Semi Automated Commercial Closed System for Autologous Leukocyte- and Platelet-Rich Plasma (l-prp) Production in Dogs: A Preliminary Study.

Simple SummaryThere are few publications on the subject of canine platelet concentrates and further studies are required to characterize these for clinical applications. The aim of this study determined platelet, erythrocyte, and leukocyte counts in canine leukocyte- and platelet rich plasma (L-PRP) produced using a commercial semi-automated closed system (CPUNT 20, Eltek group, Casale Monferrato, Alessandria, Italy). Whole blood (WB) from 30 healthy dogs was used. In 10 L-PRP bovine thrombin activated samples platelet-derived growth factor isoform BB (PDGF-BB) concentration was also measured. The CPUNT 20 produced clinically useful quantities of sterile canine L-PRP containing a high concentration of platelets (767,633 ± 291,001 μL, p < 0.001), with a 4.4 fold increase in platelet count, lower concentration of erythrocytes (528,600 ± 222,773 μL, p < 0.001) and similar concentration of leukocytes (8422 ± 6346 μL, p = 0.9918) compared with WB. Neutrophils, lymphocytes and monocytes average percent content in L-PRP was 14.8 ± 13.2, 71.7 ± 18.5 and 10.7 ± 6.4, respectively. Activated L-PRP has an average of 3442 ± 2061 pg/mL of PDGF-BB.Background: To characterize the cellular composition (platelets, erythrocytes, and leukocytes) and determine platelet-derived growth factor isoform BB (PDGF-BB) concentration in canine leukocyte- and platelet rich plasma (L-PRP) produced using a commercial semi-automated closed system. Methods: Twenty milliliters of citrated whole blood were obtained from 30 healthy un-sedated canine blood donors and processed using a semi-automated completely closed commercial system (CPUNT 20, Eltek group, Casale Monferrato, Alessandria, Italy) according to the manufacturer’s instructions. Erythrocyte, leukocyte, and platelet counts were determined in both whole blood (WB) and resultant L-PRP. The PDGF-BB concentration was evaluated after bovine thrombin activation of 10 L-PRP samples. Results: This commercial system produced on average 2.3 ± 0.7 mL of L-PRP containing a high concentration of platelets (767,633 ± 291,001 μL, p < 0.001), with a 4.4 fold increase in platelet count, lower concentration of erythrocytes (528,600 ± 222,773 μL, p < 0.001) and similar concentration of leukocytes (8422 ± 6346 μL, p = 0.9918) compared with WB. L-PRP had an average of 3442 ± 2061 pg/mL of PDGF-BB after thrombin activation. Neutrophils, lymphocytes and monocytes average percent content in L-PRP was 14.8 ± 13.2, 71.7 ± 18.5 and 10.7 ± 6.4, respectively. Conclusion: Sterile canine L-PRP prepared using this semi-automated closed system is easy to obtain, produces a significant increase in platelet count compared to WB and contains a detectable concentration of PDGF-BB after activation. Additional in vitro and in vivo studies are needed to assess inflammatory markers concentration and the therapeutic efficacy of this L-PRP in dogs.

Autologous platelet concentrates in maxillofacial regenerative therapy.

Platelet concentrates have emerged as innovative autologous blood products that enhance tissue healing and regeneration in regenerative therapy. A common feature of these products is their higher than baseline platelet concentration, which improves wound healing and tissue repair. Four main categories of products can be easily defined, based on their leukocyte content and fibrin architecture: pure platelet-rich plasma, such as Cell Separator PRP or Anitua' PRGF; leukocyte- and platelet-rich plasma (L-PRP), such as PCCS or Ace PRP; pure platelet-rich fibrin (P-PRF), such as Fibrinet PRFM; and leukocyte- and platelet-rich fibrin (L-PRF), such as Choukroun's PRF. Two families contain significant concentrations of leukocytes: L-PRP and L-PRF. These four families of products have different biological signatures and mechanisms and obviously different clinical applications. An L-PRF membrane releases growth factors and matrix proteins over a period longer than 7 days, whereas a PRP gel matrix releases and disperses its growth factors in a relatively quick download. In the near future, simple and inexpensive products such as L-PRF are expected to have applications in oral-maxillofacial surgery, periodontal surgery, plastic surgery, orthopedic surgery, and sports medicine. Leukocytes substantially affect the intrinsic biology and properties of platelet concentrates, not only because they enhance immune function and antibacterial potential, but also because they have essential roles in the wound healing process. Unfortunately, their impact has been almost completely neglected in the literature. Improved understanding of the effects of leukocytes in wound healing is essential for development of new clinical applications of platelet concentrates.

Bioactive Fibrin Scaffolds for Use in Musculoskeletal Regenerative Medicine

Abstract Autologous fibrin matrices derived from the Leukocyte and Platelet Rich Plasma (L-PRP) and Leukocyte and Platelet Rich Fibrin (L-PRF) techniques present great potential to act as a bioactive scaffold in regenerative medicine, contributing to the maintenance of cell viability, proliferation stimulus and differentiation. In contrast, there are few studies that characterize the bioactive potential of these fibrin scaffolds by considering the process of production. The objective of this work was to characterize the intrinsic potential of maintaining cell viability of different fibrin scaffolds containing platelets and leukocytes. In order to achieve that, blood samples from a volunteer were collected and processed to obtain fibrin clots using the suggested techniques. To characterize the potential for in vitro viability, mesenchymal stem cells from human infrapatellar fat were used. The scaffolds were cellularized (1x105 cells/scaffolds) and maintained for 5 and 10 days under culture conditions with Dulbecco's Modified Eagle Medium, without addition of fetal bovine serum, and subsequently subjected to analyses by Fourrier transform infra-red spectroscopy, circular dichroism and fluorescence microscopy. The results demonstrated distinct intrinsic potential viability between the scaffolds, and L-PRP was responsible for promoting higher levels of viability in both periods of analysis. No viable cells were identified in the fibrin matrix used as controls. These results allow us to conclude that both fibrin substrates have presented intrinsic potential for maintaining cell viability, with superior potential exhibited by L-PRP scaffold, and represent promising alternatives for use as bioactive supports in musculoskeletal regenerative medicine.

The Effects of Leukocyte- and Platelet-Rich Plasma (L-Prp) and Pure Platelet-Rich Plasma (P-Prp) in a Rat Endometriosis Model

Objective: We aimed to investigate the effect of platelet‑rich plasma (PRP) derivatives, which can be produced from the patient’s blood and have minimal side effects, on endometriosis.Methods: To our knowledge, this is the first study in the literature that studies the relationship between PRP and endometriosis. Endometriosis foci were created in the first operation. In the second operation (30th day), four groups were formed wherein group 1 (n = 8) was administered saline, group 2 (n = 7) leukocyte and platelet‑rich plasma (L‑PRP), group 3 (n = 8) pure platelet‑rich plasma (P‑PRP) and group 4 (n = 10) was used to obtain PRP. In the last operation (60th day), the endometriotic foci was measured and then excised.Findings: There was no statistically significant difference between the pre and post volumes of the endometriotic foci, between their volume differences, and volume difference rates (P > 0.05). However, it was observed that existing implant volumes in all groups decreased statistically significantly within their groups by the end of the experiment compared to the previous volumes (P < 0.05).Conclusion: When the implants were assessed through histopathological scoring in terms of edema, vascular congestion, inflammatory cell infiltration, hemorrhage, epithelial line, and hemosiderin accumulation, and immunohistochemical staining was assessed in terms of VEGF, there was no significant difference in the comparison between the groups. Although L‑PRP and P‑PRP generated more reduction in the endometriosis foci, they did not create any statistical differences. Key words: L‑Prp; P‑Prp; VEGF; endometriosis.

Hyaluronic acid and fibrin from L-PRP form semi-IPNs with tunable properties suitable for use in regenerative medicine.

Autologous leukocyte- and platelet-rich plasma (L-PRP) combined with hyaluronic acid (HA) has been widely used in local applications for cartilage and bone regeneration. The association between L-PRP and HA confers structural and rheological changes that differ among individual biomaterials but has not been investigated. Therefore, the standardization and characterization of L-PRP-HA are important to consider when comparing performance results to improve future clinical applications. To this end, we prepared semi-interpenetrating polymer networks (semi-IPNs) of L-PRP and HA and characterized their polymerization kinetics, morphology, swelling ratio, stability and rheological behavior, which we found to be tunable according to the HA molar mass (MM). Mesenchymal stem cells derived from human adipose tissue (h-AdMSCs) seeded in the semi-IPNs had superior viability and chondrogenesis and osteogenesis capabilities compared to the viability and capabilities of fibrin. We have demonstrated that the preparation of the semi-IPNs under controlled mixing ensured the formation of cell-friendly hydrogels rich in soluble factors and with tunable properties according to the HA MM, rendering them suitable for clinical applications in regenerative medicine.

Centrifugation Conditions in the L-PRP Preparation Affect Soluble Factors Release and Mesenchymal Stem Cell Proliferation in Fibrin Nanofibers.

Leukocyte and platelet-rich plasma (L-PRP) is an autologous product that when activated forms fibrin nanofibers, which are useful in regenerative medicine. As an important part of the preparation of L-PRP, the centrifugation parameters may affect the release of soluble factors that modulate the behavior of the cells in the nanofibers. In this study, we evaluated the influences of four different centrifugation conditions on the concentration of platelets and leukocytes in L-PRP and on the anabolic/catabolic balance of the nanofiber microenvironment. Human adipose-derived mesenchymal stem cells (h-AdMSCs) were seeded in the nanofibers, and their viability and growth were evaluated. L-PRPs prepared at 100× g and 100 + 400× g released higher levels of transforming growth factor (TGF)-β1 and platelet-derived growth factor (PDGF)-BB due to the increased platelet concentration, while inflammatory cytokines interleukin (IL)-8 and tumor necrosis factor (TNF)-α were more significantly released from L-PRPs prepared via two centrifugation steps (100 + 400× g and 800 + 400× g) due to the increased concentration of leukocytes. Our results showed that with the exception of nanofibers formed from L-PRP prepared at 800 + 400× g, all other microenvironments were favorable for h-AdMSC proliferation. Here, we present a reproducible protocol for the standardization of L-PRP and fibrin nanofibers useful in clinical practices with known platelet/leukocyte ratios and in vitro evaluations that may predict in vivo results.

A new aspect of in vitro antimicrobial leukocyte- and platelet-rich plasma activity based on flow cytometry assessment

The current literature suggests that the antibacterial effect of leukocyte- and platelet-rich plasma (L-PRP) is directly related to platelet and leukocyte concentrations. The aim of this study was twofold: first, to evaluate the antimicrobial effect of L-PRP against selected bacterial strains in vitro, and second, to correlate this effect with leukocyte and platelet content in the final concentration. Blood was collected from 20 healthy males, and L-PRP, acellular plasma (AP), and autologous thrombin were consecutively prepared. Flow cytometry analysis of the blood, L-PRP, and AP was performed. The L-PRP gel, liquid L-PRP, and thrombin samples were tested in vitro for their antibacterial properties against seven selected bacterial strains using the Kirby–Bauer disk-diffusion method. There was notable antimicrobial activity against selected bacterial strains. No statistically significant correlations between antimicrobial activities and the platelet concentration in L-PRP were observed. Statistically significant positive correlations between selected leukocyte subtypes and antimicrobial activity were noted. A negative correlation was found between elevated monocyte count and antimicrobial activity of L-PRP against one bacterial strain studied. L-PRP possesses antimicrobial activity and can be potentially useful in the fight against certain postoperative infections. The bactericidal effect of L-PRP is caused by leukocytes, and there exists a relationship among selected leukocyte subtypes and L-PRP antimicrobial activity.

Antibacterial Activity of Leukocyte- and Platelet-Rich Plasma: An In Vitro Study.

The aim of the study was to investigate the leukocyte- and platelet-rich plasma (L-PRP) antimicrobial activity. The studied sample comprised 20 healthy males. The L-PRP gel, liquid L-PRP, and thrombin samples were tested in vitro for their antibacterial properties against selected bacterial strains using the Kirby-Bauer disc diffusion method. Two types of thrombin were used (autologous and bovine). Zones of inhibition produced by L-PRP ranged between 6 and 18 mm in diameter. L-PRP inhibited the growth of Staphylococcus aureus (MRSA and MSSA strains) and was also active against Enterococcus faecalis and Pseudomonas aeruginosa. There was no activity against Escherichia coli and Klebsiella pneumoniae. The statistically significant increase of L-PRP antimicrobial effect was noted with the use of major volume of thrombin as an activator. Additionally, in groups where a bovine thrombin mixture was added to L-PRP the zones of inhibition concerning MRSA, Enterococcus faecalis, and Pseudomonas aeruginosa were larger than in the groups with autologous thrombin. Based on the conducted studies, it can be determined that L-PRP can evoke in vitro antimicrobial effects and might be used to treat selected infections in the clinical field. The major volume of thrombin as an activator increases the strength of the L-PRP antimicrobial effect.

Sustained or higher levels of growth factors in platelet-rich plasma during 7-day storage

BackgroundThe effectiveness of platelet-rich plasma (PRP) for treating soft tissue injuries is still controversial. Most of PRPs were prepared simply by concentrating in volume and were injected right after preparation in physician offices. Neither platelet count nor growth factors were quantitated in advance. We prepared and stored leukocyte and platelet-rich plasma (L-PRP) by regular separation protocols for blood components in the blood bank. And we investigated the dynamic change of growth factors in the L-PRPs over the period of storage. MethodsThe L-PRPs were prepared by 2-step centrifugation and stored agitatedly at22 °C for 7 days in the platelet incubator of blood bank. Levels of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF)-basic, hepatocyte growth factor (HGF), insulin-like growth factor (IGF)-1, platelet derived growth factor (PDGF)-AB, endothelial growth factor (EGF), and transforming growth factor (TGF) over the period of storage were evaluated daily after freeze-thawing to release growth factors from platelet. ResultsCompared to original whole blood, platelet concentration, VEGF, FGF-basic, PDGF-AB, EGF, and TGF-beta1 levels of L-PRPs significantly increased after PRP preparation. Both HGF and IGF-1 in L-PRPs remained the original plasma level. Platelet, FGF, and TGF-beta1 concentrations sustained during storage, and concentrations of VEGF, HGF, IGF-1, PDGF-AB, and EGF in L-PRPs increased over the period of storage. ConclusionsDuring the storage in blood bank, platelet counts and 7 growth factors sustained or reached higher level than L-PRP obtained on first day. Multiple injections of stored PRPs could become applicable by our protocol.

Effect of L-PRP treatment on wound healing after surgical skin incision in an experimental animal model

ABSTRACTAim of the study: The aim of the study was to evaluate the effect of leukocyte- and platelet-rich plasma (L-PRP) treatment on a noncomplicated would healing after surgical skin incision in an experimental animal model.Materials and Methods: The blood from 64 male Wistar rats was used to prepare L-PRP before a transverse dorsal incision was made and consecutively closed. At the same time after the surgery was completed, autologous L-PRP in the rats from the L-PRP group (n = 32) and NaCl in the control group (n = 32) were injected subcutaneously into the wound. The examination included clinical observations, laboratory examination, and examination of biopsy specimens taken from sacrificed animals on the second, third, fourth, and sixth days after the surgery (histopathological examination, immunochemistry, molecular examination).Results: In all cases, no healing process complications were noted. The intergroup comparison revealed no statistically significant differences in terms of histopathological, immunohistochemical, and molecular examinations results. In the intragroup analysis, statistically significant differences were observed within each group between periods of observations in terms of immunohistochemical and molecular examinations results.Conclusions: L-PRP treatment does not significantly accelerate a noncomplicated wound healing after surgical skin incision in an experimental animal model.

Distribution, recovery and concentration of platelets and leukocytes in L-PRP prepared by centrifugation

Platelet-rich plasma (PRP) is an autologous product prepared from whole blood (WB) that is widely used in regenerative medicine. In clinical practice, discontinuous centrifugation is used for both hand- and machine-prepared PRP. However, separation of WB fractions via centrifugation is a complex process, and the lack of clear mechanisms limits the understanding and evaluation of PRP preparation methods This paper focuses on the distribution, recovery and concentration factor of platelets and leukocytes in L-PRP (leukocyte and platelet-rich plasma) to define a concentration pattern for these blood components due to centrifugation conditions. WB collected from three healthy donors was centrifuged for 10min at 50–800 xg in a first step and then at 400 xg in a second step. The results from the first centrifugation step showed most platelets to be distributed in the upper layer (UL) and the buffy coat (BC), with approximately 14.5±5.2% retained in the bottom layer (BL). Most leukocytes were present in the BL. The greatest platelet recoveries from L-PRP were obtained at up to 150 xg (88.5±16.9%). The cumulative concentration factors with respect to the WB from the second centrifugation step were 6 and 1.2 for platelets and leukocytes, respectively. Thus, the concentration patterns delineated three centrifugation ranges with platelet/leukocyte ratios of 205±18, 325±15 and 107±4 and lymphocyte/granulocyte ratios of 1.54±0.74, 0.90±0.08 and 0.42±0.07. These findings contribute to a scientifically based standardization of L-PRP preparations.

Comparative evaluation of leukocyte- and platelet-rich plasma and pure platelet-rich plasma for cartilage regeneration

Platelet-rich plasma (PRP) has gained growing popularity in the treatment of articular cartilage lesions in the last decade. However, the potential harmful effects of leukocytes in PRP on cartilage regeneration have seldom been studied in vitro, and not at all in vivo yet. The objective of the present study is to compare the effects of leukocyte- and platelet-rich plasma (L-PRP) and pure platelet-rich plasma (P-PRP) on cartilage repair and NF-κB pathway, in order to explore the mechanism underlying the function of leukocytes in PRP in cartilage regeneration. The constituent analysis showed that P-PRP had significantly lower concentrations of leukocytes and pro-inflammatory cytokines compared with L-PRP. In addition, cell proliferation and differentiation assays indicated P-PRP promoted growth and chondrogenesis of rabbit bone marrow mesenchymal stem cells (rBMSC) significantly compared with L-PRP. Despite similarity in macroscopic appearance, the implantation of P-PRP combining rBMSC in vivo yielded better cartilage repair results than the L-PRP group based on histological examination. Importantly, the therapeutic effects of PRP on cartilage regeneration could be enhanced by removing leukocytes to avoid the activation of the NF-κB pathway. Thus, PRP without concentrated leukocytes may be more suitable for the treatment of articular cartilage lesions.

The Properties of 3 Different Plasma Formulations and Their Effects on Tendinopathic Cells

Background: Tendinopathies are attributed to failure of the healing process and inadequate tissue remodeling. Plasma injections can trigger regenerative responses by modifying the molecular microenvironment. Purpose: To examine the differences in the mitotic, chemotactic, anabolic, and inflammatory effects between leukocyte- and platelet-rich plasma (L-PRP), platelet-rich plasma (PRP), and platelet-poor plasma (PPP). Study Design: Controlled laboratory study. Methods: Tendinopathic cells were cultured in 3-dimensional (3D) hydrogels formed using PPP, PRP, and L-PRP. Cell migration was evaluated using a μ-Slide chemotaxis chamber with video microscopy. Proliferation was assessed using XTT assays. Expression of genes associated with matrix turnover, including type 1 collagen (COL1A1), COL3A1, aggrecan, decorin, fibronectin, matrix metalloproteinase 1 (MMP-1), MMP-3, A Disintegrin-Like And Metalloprotease With Thrombospondin Type 1 Motif proteins 4 (ADAMTS-4), and ADAMTS-5, was assessed using real-time reverse-transcription polymerase chain reaction. Secreted inflammatory proteins, including interleukin (IL)–1β, IL-6, IL-8, monocyte chemotactic protein 1 (MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES), as well as vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF), were quantified using enzyme-linked immunosorbent assay. Results: Tendinopathic cells migrate at a higher velocity along L-PRP and PRP than along PPP gradients. PRP and L-PRP promote hypercellularity. PPP and PRP showed more pronounced anabolic properties, as demonstrated by enhanced COL1A1 and COL3A1 and reduced MMP-1 expression. Decorin, fibronectin, and aggrecan were downregulated in L-PRP compared with PPP and PRP. L-PRP and PRP were shown to be more proinflammatory than PPP in terms of IL-6 secretion, but cells in PPP showed MCP-1high phenotype. CTGF secretion was significantly reduced in L-PRP compared with PPP and PRP. Conclusion: The main advantages of L-PRP and PRP use, compared with PPP, include their stronger chemotactic and proliferative properties. While PPP and PRP stimulate matrix anabolism, L-PRP is more proinflammatory. Emphasis should be placed on the temporal needs and biological characteristics of injured tendons, and plasma formulations need to be tailored accordingly. Clinical Relevance: Versatile systems allowing the preparation of different plasma formulations, such as PPP, PRP, or L-PRP, can help refine clinical applications by taking advantage of their different biological properties.

Benefit of Leukocyte- and Platelet-Rich Plasma in Operative Wound Closure in Oral and Maxillofacial Surgery.

This article reports the influence of an autologous leukocyte- and platelet-rich plasma (L-PRP) injection as a minimally invasive method on supporting wound healing processes after a mandibular odontogenic cystectomy and double mandibular fracture fixation. 113 patients were enrolled into a control group (received no L-PRP injection) and 102 patients were enrolled into an L-PRP group with an oral mucosa incision. 18 patients after a double mandibular fracture were operated on using 2 external submandibular approaches receiving no fluids in the right site (a control group) and an L-PRP injection in the left incision (L-PRP group). Clinical observations showed that the oral mucosa healed faster in patients treated with L-PRP, in comparison to cases where inductive biomaterial was not added. Pain at the L-PRP injection site was relieved within few hours after an operation in patients with double mandibular fractures. However, there were no differences observed in the progression of the healing process. L-PRP possesses inductive properties that could stimulate healing processes and it seems to be one of the most promising methods in the future for the treatment of soft tissue defects.