Characterization of a novel mouse platelet transfusion model.

BACKGROUND AND OBJECTIVES: Platelet transfusions are increasing with medical advances. Based on FDA criteria, platelet units are assessed by in vitro measures; however, it is not known how platelet processing and storage duration affect function in vivo. Our study's aim was to develop a novel platelet transfusion model stored in mouse plasma that meets FDA criteria adapted to mice, and transfused fresh and stored platelets are detectable in clots in vivo. STUDY DESIGN AND METHODS: Platelet units stored in mouse plasma were prepared using a modified platelet-rich plasma (PRP) collection protocol. Characteristics of fresh and stored units, including pH, cell count, in vitro measures of activity, including activation and aggregation, and post-transfusion recovery (PTR), were determined. Lastly, a tail transection assay was conducted using mice transfused with fresh or stored units, and transfused platelets were identified by confocal imaging. RESULTS: Platelet units had acceptable platelet and white cell counts and were negative for bacterial contamination. Fresh and 1-day stored units had acceptable pH; the platelets were activatable by thrombin and adenosine diphosphate, agreeable with thrombin, had acceptable PTR, and were present in vivo in clots of recipients after tail transection. In contrast, 2-day stored units had clinically unacceptable quality. CONCLUSION: We developed mouse platelets for transfusion analogous to human platelet units using a modified PRP collection protocol with maximum storage of 1 day for an 'old' unit. This provides a powerful tool to test how process modifications and storage conditions affect transfused platelet function in vivo.

Autologous platelet-rich plasma treatment for moderate-severe Asherman syndrome: the first experience.

PURPOSE: Treatment of Asherman syndrome (AS) presents a significant clinical challenge. Based on our in vitro data showing that PRP could activate endometrial cell proliferation and migration, we hypothesized that intrauterine infusion of autologous platelet-rich plasma (PRP) may improve endometrial regeneration and fertility outcomes in patients with moderate-severe AS. MATERIALS AND METHODS: Subjects with moderate-severe AS were randomized to PRP or saline control administered following hysteroscopic adhesiolysis. Due to relative inability to randomize patients to the control group, after initial randomization of 10 subjects (6 in PRP and 4 in control groups), the remainder were prospectively enrolled in PRP group (n = 9), with 11 historic controls added to control group, for a total of 30 subjects (PRP n = 15; saline control n = 15). Right after hysteroscopy, 0.5-1 mL of PRP or saline was infused into the uterus via a Wallace catheter, followed by estrogen therapy. The primary outcomes were changes in endometrial thickness (EMT, checked in 3 weeks) and in menstrual flow; secondary outcomes were pregnancy and live birth rates. EMT and menstrual bleeding pattern were assessed before and after the intervention. Pregnancy was assessed over a 6-month period. RESULTS: There were no statistically significant differences in age, gravidity/parity, cause of AS, preoperative menses assessment, AS hysteroscopy score, and intrauterine balloon placement between the groups. There was no statistically significant difference (p = 0.79) in EMT pre-PRP infusion for control (5.7 mm, 4.0-6.0) and study arm (5.3 mm, 4.9-6.0). There was no statistically significant change (p = 0.78) in EMT after PRP infusion (1.4 mm, - 0.5-2.4) vs saline (1.0 mm, 0.0-2.5). Patients tolerated the procedure well, with no adverse effects. There was no difference in the predicted likelihood of pregnancy (p = 0.45) between the control (0.67, 0.41-0.85) and study arm (0.53, 0.29-0.76). CONCLUSIONS: PRP was well accepted and tolerated in AS patients. However, we did not observe any significant EMT increase or improved pregnancy rates after adding PRP infusion, compared to standard treatment only. The use of intrauterine PRP infusion may be a feasible option, and its potential use must be tested on a larger sample size of AS patients.

Effects of Platelet-Rich Plasma on Cellular Populations of the Central Nervous System: The Influence of Donor Age.

Platelet-rich plasma (PRP) is a biologic therapy that promotes healing responses across multiple medical fields, including the central nervous system (CNS). The efficacy of this therapy depends on several factors such as the donor's health status and age. This work aims to prove the effect of PRP on cellular models of the CNS, considering the differences between PRP from young and elderly donors. Two different PRP pools were prepared from donors 65‒85 and 20‒25 years old. The cellular and molecular composition of both PRPs were analyzed. Subsequently, the cellular response was evaluated in CNS in vitro models, studying proliferation, neurogenesis, synaptogenesis, and inflammation. While no differences in the cellular composition of PRPs were found, the molecular composition of the Young PRP showed lower levels of inflammatory molecules such as CCL-11, as well as the presence of other factors not found in Aged PRP (GDF-11). Although both PRPs had effects in terms of reducing neural progenitor cell apoptosis, stabilizing neuronal synapses, and decreasing inflammation in the microglia, the effect of the Young PRP was more pronounced. In conclusion, the molecular composition of the PRP, conditioned by the age of the donors, affects the magnitude of the biological response.

Platelet-Rich Plasma: New Performance Understandings and Therapeutic Considerations in 2020.

Emerging autologous cellular therapies that utilize platelet-rich plasma (PRP) applications have the potential to play adjunctive roles in a variety of regenerative medicine treatment plans. There is a global unmet need for tissue repair strategies to treat musculoskeletal (MSK) and spinal disorders, osteoarthritis (OA), and patients with chronic complex and recalcitrant wounds. PRP therapy is based on the fact that platelet growth factors (PGFs) support the three phases of wound healing and repair cascade (inflammation, proliferation, remodeling). Many different PRP formulations have been evaluated, originating from human, in vitro, and animal studies. However, recommendations from in vitro and animal research often lead to different clinical outcomes because it is difficult to translate non-clinical study outcomes and methodology recommendations to human clinical treatment protocols. In recent years, progress has been made in understanding PRP technology and the concepts for bioformulation, and new research directives and new indications have been suggested. In this review, we will discuss recent developments regarding PRP preparation and composition regarding platelet dosing, leukocyte activities concerning innate and adaptive immunomodulation, serotonin (5-HT) effects, and pain killing. Furthermore, we discuss PRP mechanisms related to inflammation and angiogenesis in tissue repair and regenerative processes. Lastly, we will review the effect of certain drugs on PRP activity, and the combination of PRP and rehabilitation protocols.

Avaliação morfológica do concentrado autólogo de plaquetas em cães sob refrigeração e criopreservação em DMSO 6% / [Morphological evaluation of the autologous platelet concentrate in dogs under refrigeration and criopreservation in 6% DMSO]

The morphological characteristics of the autologous platelet concentrate (APC) of 31 dogs were evaluated after cooling and freezing in 6% DMSO. Blood from the jugular vein of each patient was collected and centrifuged at 191g for six minutes to obtain APC. In the fresh sample, the platelet count, MPV, PDW and cell morphology were evaluated. Four samples of each animal were sent for storage, one refrigerated at 4°C for seven days, another for 30 days and two more stored in a freezer at -80°C in the same time interval, using 6% DMSO as cryoprotectant. The conserved samples were submitted to the same laboratory analysis as the fresh sample. There was a difference between fresh and preserved samples for platelet count, cell concentration, MPV and PDW (P<0.05), except in the 30-day refrigerated group, which showed severe morphological changes. In the frozen group for seven days, no difference was observed in the percentage of activation (P>0.05). The results obtained lead to the conclusion that cryopreservation with 6% DMSO at -80°C for seven days is a favorable option for the maintenance of platelet concentrations and the morphological characteristics of APC in dogs.(AU)

Leukocyte-rich platelet-rich plasma application in post-traumatic osteoarthritis with popliteal cyst: a case report.

Aim: To describe the successful treatment of a Baker's cyst in the setting of post-traumatic osteoarthritis using ultrasound-guided injection of platelet-rich plasma. Setting: Outpatient sports clinic. Patient: 29-year old male basketball player. Case description: The patient presented with 2-months history of right knee pain, 17 months after undergoing right knee anterior cruciate ligament reconstruction surgery. Exam revealed medial joint line and medial collateral ligament tenderness with posterior knee swelling. After aspiration, a corticosteroid injection was administered with temporary symptom relief. Diagnostic ultrasound examination confirmed the Baker's cyst. The patient then underwent two serial leukocyte-rich platelet-rich plasma injections into his right knee. Results: The patient reported complete resolution of pain and cyst size. Conclusion: Leukocyte-rich platelet-rich plasma may be considered as a treatment option for patients with Baker's cysts in the setting of post-traumatic osteoarthritis.

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.

Pathogen reduction with riboflavin and ultraviolet light induces a quasi-apoptotic state in blood leukocytes.

BACKGROUND: Alloimmunization to platelet-rich plasma (PRP) transfusions can cause adverse reactions such as platelet refractoriness or transplant rejection. Pathogen reduction treatment with ultraviolet light and riboflavin (UV + R) of allogeneic PRP was shown to reduce allogeneic antibody responses and confer partial antigen-specific immune tolerance to subsequent transfusions in mice. Studies have shown that UV + R was effective at both rapidly killing donor white blood cells (WBCs) and reducing their ability to stimulate an allogeneic response in vitro. However, the manner in which UV + R induces WBC death and its associated role in the immune response to treated PRP is unknown. METHODS AND MATERIALS: This study evaluates whether UV + R causes WBC apoptosis by examining phosphatidylserine exposure on the plasma membrane, membrane asymmetry, caspase activity, and chromatin condensation by flow cytometry. The immunogenicity of WBCs killed with UV + R versus apoptotic or necrotic pathways was also examined in vivo. RESULTS: WBCs after UV + R exhibited early apoptotic-like characteristics including phosphatidylserine exposure on the outer leaflet of the plasma membrane and loss of membrane asymmetry, but unlike canonical apoptotic cells, caspase activity and chromatin condensation were not apparent. However, in vivo studies demonstrated, unlike untreated or necrotic WBCs, both apoptotic WBCs and UV + R-treated WBCs failed to prime alloantibody responses to subsequent untreated transfusions. CONCLUSION: Overall, the mechanism of WBC death following UV + R treatment shares some membrane characteristics of early apoptosis but is distinct from classic apoptosis. Despite these differences, UV + R-treated and apoptotic WBCs both offer some protection from alloimmunization.

The Current Status of Cell-Based Therapies for Primary Knee Osteoarthritis.

There is a growing interest in cell therapy for knee osteoarthritis. This study systematically reviews the current status of cell-based therapies. The authors review treatment modalities, clinical outcomes, and the economics of cell therapy. Inclusion criteria were articles containing cellular therapy, platelet-rich plasma, and knee osteoarthritis in the title. Letters, editorial material, abstracts not published, and manuscripts with incomplete data were excluded. Forty-two articles met these inclusion criteria and were critically reviewed. Cell-based therapy holds promise as a means of restoring deficient local cartilage cell populations. There is no evidence-based information for the use of cell-based therapies in knee osteoarthritis.

Haemostasis and analgesia with autologous platelet-rich plasma in tonsillectomy.

OBJECTIVE: A single-centre, single-blinded prospective experimental study was conducted to determine the effectiveness of autologous platelet-rich plasma applied to the tonsillar bed post-operatively in reducing post-operative pain and haemorrhage. METHODS: Platelet-rich plasma, prepared prior to surgery, was applied with calcium gluconate to one randomly chosen tonsillar fossa. Pain and haemorrhage were analysed, using a visual analogue scale and a pre-defined grading scale respectively, four times on the day of surgery at 2-hourly intervals, and thrice on the following day. RESULTS: The pain score and haemorrhage grade on the test side were lower than on the control side. These findings were statistically significant. CONCLUSION: This pilot study, conducted in India, revealed valid positive results for a promising new technology. The manual preparation of platelet-rich plasma could be automated in the future to allow a larger sample size.

Injeção de agregados plaquetários no rejuvenescimento facial: uma revisão sistemática / Injection of platelet aggregates in facial rejuvenation: a systematic review

Introdução: Essa revisão sistemática foi conduzida para avaliar se a associação da aplicação da injeção de agregados plaquetários quando comparada a outras terapias faciais favorece no rejuvenescimento facial em pacientes adultos. Métodos: A pesquisa buscou ensaios clínicos randomizados que compararam uso de técnicas de rejuvenescimento facial isoladas com as mesmas técnicas aliadas à injeção de agregados plaquetários. A busca foi realizada em bases de dados indexadas e literatura cinzenta. A ferramenta de risco de viés da "Cochrane Collaboration" foi aplicada para a avaliação da qualidade dos estudos. Resultados: Foram identificados 7137 artigos. Apenas quatro estudos permaneceram na síntese qualitativa, e os demais foram considerados com risco indefinido de viés nos domínios chaves. Conclusão: Existem poucos estudos na literatura que comparam o uso de agregados plaquetários em rejuvenescimento facial e os que estão disponíveis têm risco de viés "indefinido" ou "alto". Há necessidade de realizar mais estudos clínicos bem delineados que comparem o uso de injeção de agregados plaquetários associados ou não às técnicas de rejuvenescimento facial.

Introduction: This systematic review was conducted to assess whether the use of a platelet aggregate injection with or without associated facial rejuvenation techniques favors facial rejuvenation in adult patients. Methods: Randomized clinical trials that compared the use of techniques for facial rejuvenation alone with the same techniques coupled with the injection of platelet aggregates were searched. The search was performed in indexed databases and in the gray literature. The Cochrane Collaboration bias risk tool was applied to assess the quality of the studies. Results: In total, 7137 articles were identified. Only four studies remained in the qualitative synthesis, and the others were considered as having undefined bias risk in the key domains. Conclusion: There are few studies in the literature that compare the use of platelet aggregates in facial rejuvenation and those that are available have a risk of "undefined" or "high" bias. There is a need for more well-designed clinical studies comparing the use of platelet aggregate injection with or without associated facial rejuvenation techniques.

Development of Autologous Platelet-Rich Plasma Mixed-Microfat as an Advanced Therapy Medicinal Product for Intra-Articular Injection of Radio-Carpal Osteoarthritis: From Validation Data to Preliminary Clinical Results.

Wrist osteoarthritis (OA) is one of the most common conditions encountered by hand surgeons with limited efficacy of non-surgical treatments. The purpose of this study is to describe the Platelet-Rich Plasma (PRP) mixed-microfat biological characteristics of an experimental Advanced Therapy Medicinal Product (ATMP) needed for clinical trial authorization and describe the clinical results obtained from our first three patients 12 months after treatment (NCT03164122). Biological characterization of microfat, PRP and mixture were analysed in vitro according to validated methods. Patients with stage four OA according to the Kellgren Lawrence classification, with failure to conservative treatment and a persistent daily painful condition >40 mm according to the visual analog scale (VAS) were treated. Microfat-PRP ATMP is a product with high platelet purity, conserved viability of stromal vascular fraction cells, chondrogenic differentiation capacity in vitro and high secretion of IL-1Ra anti-inflammatory cytokine. For patients, the only side effect was pain at the adipose tissue harvesting sites. Potential efficacy was observed with a pain decrease of over 50% (per VAS score) and the achievement of minimal clinically important differences for DASH and PRWE functional scores at one year in all three patients. Microfat-PRP ATMP presented a good safety profile after an injection in wrist OA. Efficacy trials are necessary to assess whether this innovative strategy could delay the necessity to perform non-conservative surgery.

Effects of a protective agent on freeze-dried platelet-rich plasma.

: Freeze-drying is an effective means of storing platelets. In this study, we investigated the effects of a protective agent on freeze-dried platelet-rich plasma (FD-PRP) after a 12-week preservation period. Platelet structure was measured by transmission electron microscopy (TEM), and the expression levels of procaspase activating compound (PAC)-1 and CD62P were measured by flow cytometry. The levels of transforming growth factor-beta (TGF-ß), platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) were determined by ELISA. The effect of FD-PRP on cell proliferation was measured by cell counting. TEM revealed that most platelets were intact, and their internal structure was evident. The expression levels of the platelet activation marker CD62P in FD-PRP and fresh PRP were 36.83% ±â€Š8.21 and 35.47% ±â€Š4.11, respectively, without a significant difference (P > 0.05). The expression levels of PAC-1 in FD-PRP and fresh PRP were 3.23% ±â€Š0.49 and 2.83% ±â€Š0.44, respectively, without a significant difference (P > 0.05). Upon activation of FD-PRP and fresh PRP by thrombin, the levels of TGF-ß, PDGF and VEGF were not significantly decreased in FD-PRP. Moreover, FD-PRP promoted cell proliferation in a manner similar to that of fresh PRP. The protective agent maintained the biological activity of FD-PRP after a 12-week preservation period.

The Role of Platelet-Rich Plasma in Cartilage Pathology: An Updated Systematic Review of the Basic Science Evidence.

PURPOSE: To review the basic science studies on platelet-rich plasma (PRP) for cartilage and determine whether there has been an improvement in methodology and outcome reporting that would allow for a more meaningful analysis regarding the mechanism of action and efficacy of PRP for cartilage pathology. METHODS: The PubMed/MEDLINE and EMBASE databases were screened in May 2017 with publication dates of January 2011 through May 2017 using the following key words: "platelet-rich plasma OR PRP OR autologous conditioned plasma (ACP) OR ACP AND cartilage OR chondrocytes OR chondrogenesis OR osteoarthritis OR arthritis." Two authors independently performed the search, determined study inclusion, and extracted data. Data extracted included cytology/description of PRP, study design, and results. RESULTS: Twenty-seven studies (11 in vitro, 13 in vivo, 3 in vitro and in vivo) met the inclusion criteria and were included in the study. All of the studies (100%) reported the method by which PRP was prepared. Two studies reported basic cytologic analysis of PRP, including platelet, white blood cell, and red blood cell counts (6.7%). Nine studies reported both platelet count and white blood cell count (30.0%). Twelve studies reported platelet count alone (40.0%). Nine studies (30.0%) made no mention at all as to the composition of the PRP used. PRP was shown to increase cell viability, cell proliferation, cell migration, and differentiation. Several studies demonstrated increased proteoglycan and type II collagen content. PRP decreased inflammation in 75.0% of the in vitro studies reporting data and resulted in improved histologic quality of the cartilage tissue in 75.0% of the in vivo studies reporting data. CONCLUSIONS: Although the number of investigations on PRP for cartilage pathology has more than doubled since 2012, the quality of the literature remains limited by poor methodology and outcome reporting. A majority of basic science studies suggest that PRP has beneficial effects on cartilage pathology; however, the inability to compare across studies owing to a lack of standardization of study methodology, including characterizing the contents of PRP, remains a significant limitation. Future basic science and clinical studies must at a minimum report the contents of PRP to better understand the clinical role of PRP for cartilage pathology. CLINICAL RELEVANCE: Establishing proof of concept for PRP to treat cartilage pathology is important so that high-quality clinical studies with appropriate indications can be performed.

Allogeneic platelet rich plasma serves as a scaffold for articular cartilage derived chondroprogenitors.

Limited self-restorative ability of the cartilage has necessitated the use of cell and tissue engineering based therapies. Recent advances in the isolation, expansion and characterization of articular cartilage derived chondroprogenitors(CPs) has gained popularity in its role for cartilage repair. Platelet rich plasma (PRP) is a reliable biological scaffold for in-vitro and in-vivo studies with reported therapeutic applications in cartilage and bone pathologies. The aim of this study was to evaluate whether human allogeneic PRP could serve as a biological scaffold for chondroprogenitors (CPs) in cartilage repair. CPs were isolated from the superficial layer of three osteoarthritic knee joints by fibronectin adhesion assay and characterized using flow cytometric analysis. Allogeneic citrated blood was harvested from three subjects to obtain PRP. CPs at a concentration of one million cells per ml were gelled with PRP using calcium chloride. The PRP-CP scaffolds were subjected for adipogeneic, osteogenic, chondrogeneic differentiation and processed for post differentiation-staining studies (Oil Red O, Von Kossa, Alcian blue staining), immunofluorescence (collagen II) and live dead assays (Calcein AM-Ethidium Homodimer). We show that PRP was able to sustain CP cell viability and differentiate towards adipogenic, osteogenic and chondrogenic lineage under appropriate culture conditions. We also noted positive extracellular matrix production in PRP-CP scaffolds cultured without chondrogenic supplementation. Our results suggest that PRP could be a promising bio-active scaffold due to its synergistic effect in supporting cell proliferation, maintaining cell viability and favoring extracellular matrix production. PRP can be used as biological scaffold for the delivery of CPs in cartilage healing.

Platelet-rich plasma or blood-derived products to improve endometrial receptivity?

The use of platelet-rich plasma (PRP) to improve endometrial receptivity is gaining increasing attention in assisted reproduction technologies. The authors report that autologous PRP intrauterine administration improves pregnancy and birth rates, particularly in cases of patients presenting poor endometrial growth. Different groups of scientists proposed a similar approach years ago using whole blood-derived products also to improve endometrial receptivity. The important role played by cytokines and growth factors during embryo implantation has been well-known for a long time. These signaling molecules are present and released by blood cells during physiological, normal endometrial growth and implantation. Similar blood mediators are released from platelet granules upon a blood vessel injury. Methods described for PRP preparation for intrauterine administration are not precise, and they seem to be similar to those used to prepare peripheral blood-derived products. Thus, it is possible that when preparing PRP from whole blood, the final plasma product used as "PRP" contains platelets in addition to the important cytokines and growth factors released by the peripheral blood mononuclear cells present in the whole blood. Precise knowledge of the identity, concentration, and effects of the individual blood factors, their origin, whether platelets or blood mononuclear cells, will greatly contribute to improve and to make results obtained in fertility treatments more repeatable.

Concentrations of Blood Components in Commercial Platelet-Rich Plasma Separation Systems: A Review of the Literature.

BACKGROUND: Platelet-rich plasma (PRP) has proven to be a very safe therapeutic option in the treatment of tendon, muscle, bone, and cartilage injuries. Currently, several commercial separation systems are available for the preparation of PRP. The concentrations of blood components in PRP among these separation systems vary substantially. PURPOSE: To systematically review and evaluate the differences between the concentrations of blood components in PRP produced by various PRP separation systems. STUDY DESIGN: Systematic review. METHODS: MEDLINE/PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE were searched for studies that compared the concentrations of blood components and growth factors in PRP between various separation systems and studies that reported on the concentrations of blood components and growth factors of single separation systems. The primary outcomes were platelet count, leukocyte count, and concentration of growth factors (eg, platelet-derived growth factor-AB [PDGF-AB], transforming growth factor-ß1 [TGF-ß1], and vascular endothelial growth factor [VEGF]). Furthermore, the preparation protocols and prices of the systems were compared. RESULTS: There were 1079 studies found, of which 19 studies were selected for inclusion in this review. The concentrations of platelets and leukocytes in PRP differed largely between, and to a lesser extent within, the studied PRP separation systems. Additionally, large differences both between and within the studied PRP separation systems were found for all the growth factors. Furthermore, preparation protocols and prices varied widely between systems. CONCLUSION: There is a large heterogeneity between PRP separation systems regarding concentrations of platelets, leukocytes, and growth factors in PRP. The choice for the most appropriate type of PRP should be based on the specific clinical field of application. As the ideal concentrations of blood components and growth factors for the specific fields of application are yet to be determined for most of the fields, future research should focus on which type of PRP is most suitable for the specific field.

An important and overlooked parameter in platelet rich plasma preparation: The mean platelet volume.

BACKGROUND: The platelets are the most heterogeneous cellular elements of the blood in size whereas larger platelets have more granules that make them more reactive rather than their smaller counterparts. OBJECTIVES: The aim of this study is to report the distribution of platelets in the plasma after centrifugation steps. METHODS: Twelve healthy male subjects were enrolled.5.4 mL of whole blood samples were collected for each tube containing 0.6 mL of acid citrate dextrose. Four samples were centrifuged at the force of 180 × g for 15 minutes. Then, 0.6 mL buffy coat was drawn from one of the four centrifuged tubes and 1/3 of the lower layer of the plasma (1.0 mL) from the second centrifuged tube; 1/3 of the middle(1.0 mL) and 1/3 of the upper layer (1.0 mL) of the plasma from third and fourth ones were drawn for blood analysis. RESULTS: Blood analysis including MPV and platelet concentrations were significantly different between the layers (P < .05). Together buffy coat and lower third of plasma layers contain 87% of the entire platelet mass. CONCLUSIONS: Platelets should not be argued only with their concentration, but it would be appropriate to evaluate with their yielded concentration and volume with MPV together while comparing PRP preparation protocols and kits.

Treatment of male pattern alopecia with platelet-rich plasma: A double-blind controlled study with analysis of platelet number and growth factor levels.

BACKGROUND: Promising results with platelet-rich plasma (PRP) in androgenetic alopecia that could be associated with platelet number and growth factor levels were described. OBJECTIVE: Analyze the platelet countand growth factor levels in PRP and their correlation with hair growth parameters evaluated by using the TrichoScan (Tricholog GmbH, Freiburg, Germany). METHODS: A total of 26 patients were randomized to receive 4 subcutaneous injections of PRP or saline. Hair growth, hair density, and percentage of anagen hairs were evaluated by using the TrichoScan method before injection, 15 days after the last injection, and again 3 months after the last injection. Growth factors (platelet-derived growth factor, epidermal growth factor, and vascular endothelial growth factor) were measured by the Luminex method (Millipore, Bedford, MA). RESULTS: We demonstrated a significant increase in hair count (P = .0016), hair density (P = .012) and percentage of anagen hairs (P = .007) in the PRP group versus in the control group, without correlation with platelet counts or quantification of the growth factors in PRP. LIMITATIONS: Other growth factors that could be related to response to PRP were not evaluated. CONCLUSION: Our data favor the use of PRP as a therapeutic alternative in the treatment of androgenetic alopecia. The lack of association between platelet count, platelet-derived growth factor, epidermal growth factor, and vascular endothelial growth factor levels and clinical improvement suggest that other mechanisms could be involved in this response.

Leukocyte-Poor Platelet-Rich Plasma-Derived Growth Factors Enhance Human Fibroblast Proliferation In Vitro.

BACKGROUND: Leukocyte-poor platelet-rich plasma (LP-PRP) from peripheral blood is currently used as a concentrated source of growth factors to stimulate repair at sites of soft tissue injury. Fibroblasts are primary mediators of wound healing. Thus, we aimed to assess the positive effect of LP-PRP on human fibroblast proliferation in vitro. METHODS: LP-PRP was prepared from 49 donors. The fibroblasts were seeded, and at 24 hours after seeding, 1 × 107/10 µL LP-PRP was added once to each well. The cells were harvested 10 times during study period at our planned points, and we examined cell proliferation using the water-soluble tetrazolium salt-1 assay. We collected the supernatants and measured the amount of growth factors such as platelet-derived growth factor (PDGF)-AB/BB, insulin-like growth factor-1 (IGF-1), transforming growth factor-ß1 (TGF-ß1), and vascular endothelial growth factor (VEGF), which are known to be involved in wound healing processes, by multiplex assay. RESULTS: Human fibroblasts treated with LP-PRP showed a significant increase in proliferation when compared to untreated controls (p < 0.001 at days 4, 6, and 8). Multiplex cytokine assays revealed various secretion patterns. PDGF-AB/BB appeared at early time points and peaked before fibroblast proliferation. IGF-1 and TGF-ß1 secretion gradually increased and peaked on days 4 and 6 post-treatment. The early VEGF concentration was lower than the concentration of other growth factors but increased along with cell proliferation. CONCLUSIONS: Platelets in LP-PRP release growth factors such as PDGF, IGF-1, TGF-ß1 and VEGF, and these growth factors have a promoting effect for human fibroblast proliferation, one of the important mediators of wound healing. These results suggest that growth factors derived from LP-PRP enhance the proliferation of human fibroblast.