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.

The effect of platelet-rich plasma injection on chronic Achilles tendinopathy and acute Achilles tendon rupture.

Several clinical trials exploring the effect of platelet-rich plasma (PRP) on Achilles tendon rupture (ATR) or Achilles tendinopathy (AT) have been published. However, current evidence is limited to small-sized trials. This study aims to evaluate whether PRP improves the outcomes of ATR or AT. PubMed, Web of Science, EMBASE, and Cochrane Library databases were searched to identify randomized controlled trials comparing PRP injection versus placebo for ATR or AT. Eleven studies with 574 patients were included. Quantitative synthesis suggested that compared with placebo, AT patients in PRP group had higher VISA-A score improvement at six-week follow-up (mean difference (MD) = 2.64; 95% CI) = 1.12 to 4.15). However, there was no significant difference between two groups for VISA-A score improvement at three-month follow-up (MD = 0.93; 95% CI = -2.75 to 4.62), or 6-month follow-up (MD = 5.46; 95% CI = -1.19 to 12.11). In ATR patients, quantitative synthesis suggested that no significant difference was seen between PRP and control group at 3-month, 6-month, and 1-year follow-up. In addition, no significant difference was detected between the two groups in improving tendon thickness and pain for AT patients, and no significant difference was seen in improving heel-rise work, maximum heel-rise height, dorsal and plantar flexion, rate of returning to sports activities, and complication for ATR patients. To conclude, no evidence indicates that PRP injection can improve the patient-reported/clinical/functional outcomes of AT or ATR. The increasing times of PRP injection could improve the outcomes, and further clinical randomized controlled trials are expected to be conducted to verify this hypothesis.

Platelet-rich plasma for the treatment of burn wounds: A meta-analysis of randomized controlled trials.

BACKGROUND: To evaluate the efficacy and safety of platelet-rich plasma in the treatment of burn wounds through a meta-analysis of randomized controlled trials. METHODS: We conducted a comprehensive study from electronic medical journal databases. The primary outcome was healing rate, and the secondary outcomes were healing time, adverse events, pain score and scar score. The data was analyzed using Review Manager 5.3 and Stata 12. The odds ratio (OR) among different groups was calculated by using 95 % confidence interval (CI). RESULTS: We included 8 randomized controlled trials with a total of 539 patients. The results showed that platelet-rich plasma could improve the healing rate of burn wound (OR 4.43, 95 % CI 2.13-9.22). The wound healing time of the platelet-rich plasma treatment group was significantly shorter than that of the conventional treatment group (OR -4.23, 95 % CI -5.48 to -2.98), both the superficial burn (OR -3.80, 95 % CI -4.53 to -3.07) and the deep burn group (OR -4.65, 95 % CI -6.90 to -2.40) had shorter healing time. Otherwise, the incidences of adverse events (OR 0.30, 95 % CI 0.11-0.78), pain score (OR -0.80, 95 % CI -1.40 to -0.21) and scar score (OR -0.38, 95 % CI -0.69 to -0.07) were all better in the platelet rich plasma treatment group. CONCLUSION: Topical platelet-rich plasma treatment on burn wounds can improve wound healing and reduce the incidence of adverse events. Further research is needed to standardize the preparation and use of platelet-rich plasma and to evaluate the long-term clinical outcome of platelet-rich plasma in the treatment of burn wounds.

An Optimized Extract, Named Self-Growth Colony, from Platelet-Rich Plasma Shows Robust Skin Rejuvenation and Anti-Ageing Properties: A Novel Technology in Development of Cosmetics.

INTRODUCTION: Inspired by application of platelet-rich plasma (PRP) in skin treatment during injuries, an extracting method was developed here to recover high amounts of cytokines and growth factors from PRP; this prepared extract was named as self-growth colony (SGC). METHODS: In optimization of SGC preparation, various parameters were tested, for example, centrifugation force, freeze-thaw, sonication, and inclusion of calcium chelator. The amounts of cytokines and growth factors, including platelet factor 4, ß-thromboglobulin, epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, were measured by ELISA assay. RESULTS: By comparing to PRP, the prepared SGC contained a significant higher amount of measured growth factors. In addition, the degradation of growth factors within SGC during the storage was calibrated, which showed better stability as compared to that of PRP preparation. Having possible application in skin care, the optimized SGC was chemically standardized by using the enrichment of growth factors. Application of SGC in cultured keratinocytes stimulated the wound healing of injured cultures. In line to this notion, SGC was applied onto human skin, and thereafter the robust improvement of skin properties was revealed. CONCLUSIONS: The potential application of SGC in treating skin rejuvenation and ageing, as well as its elaborated application for medical purpose, that is, wound healing, was illustrated.

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.

Application of high-sensitivity flow cytometry in combination with low-voltage scanning electron microscopy for characterization of nanosized objects during platelet concentrate storage.

Platelet concentrates are used in clinic for therapy and prophylaxis of conditions associated with platelet deficiency or malfunction. The characteristics of platelet concentrates gradually change during pretransfusion storage, affecting their clinical effectiveness and the risk of adverse transfusion reactions. The presence of platelet-derived membrane vesicles is an important characteristic of platelet concentrates. Due to their functionality, changes in the number and molecular compositions of platelet-derived vesicles have major effects on the clinical properties of platelet preparations. The existence of different subpopulations of membrane vesicles requires analytical methods capable of providing information at the individual vesicle level. Such methods include flow cytometry and electron microscopy. However, conventional flow cytometry has certain limitations, since the diameters of many platelet-derived membrane vesicles are smaller than its detection limit. The use of classical scanning electron microscopy is also limited due to the requirement for coating with a layer of conductive material, which impedes the detection of small extracellular vesicles. Here, a combination of high-sensitivity flow cytometry and low-voltage scanning electron microscopy was used to increase sensitivity and resolution in the detection of nanosized objects present in platelet concentrates during storage. Apheresis platelet concentrates from eight healthy adult donors were investigated on days 2 and 7 of storage. Fractions of nanosized objects were obtained by differential centrifugation. Fluorophore-conjugated antibodies were used to detect marker-positive vesicles derived from platelets (CD41), red blood cells (CD235a), leukocytes (CD45), and endothelial cells (VEGFR2). Near-spherical objects with diameters ranging from 25 to 700 nm were observed by low-voltage scanning electron microscopy in platelet concentrates and its fractions. On day 7 of storage, objects with diameters of less than 100 nm were attached to and clustered near the terminal ends of pseudopod-like projections. High-sensitivity flow cytometry showed that during storage numbers of CD41(pos) vesicles elevated more than fivefold and numbers of marker-negative nanosized objects, which did not carry any of the investigated cell type-specific markers elevated more than twofold. Major changes in both CD41(pos) vesicles and marker-negative nanosized objects abundances were observed for objects with diameters around 100 nm bead equivalents. Overall, these results emphasized the importance of application of high-sensitivity methods for monitoring the characteristics of cell-derived nanosized objects during platelet concentrate storage.

The Role of Platelet Homeostasis in a Novel Topical PRP Formulation.

BACKGROUND: Topical platelet-rich plasma (PRP) must demonstrate stability to insure biologic activity in aesthetic medicine. OBJECTIVE: The objective of this research was to evaluate the role of platelet homeostasis in a novel PRP topical cosmetic formulation to provide facial appearance improvement. METHODS: The stability of the topical PRP formulation was evaluated in vitro followed by clinical in vivo testing. The in vitro evaluation examined platelet stability and morphology over a 90-day period within the preservative cosmetic base utilizing ELISA and light microscopy (LM)/scanning electron microscopy (SEM). The in vivo clinical study enrolled 20 subjects in a 120-day double blind split face study to evaluate the effect of 5–7x concentrated PRP compared to 2–3x concentrated PRP on facial photoaging. Cosmetic effect was evaluated by the subject and the dermatologist investigator on a 5-point ordinal scale at baseline, week 8, and week 16. RESULTS: 90-day stability for the topical PRP formulation was verified via ELISA and LM/SEM. ELISA showed the PRP was more inactive than control conditions via analyte concentration curves (PDGF-AB, EGF, and P-Selectin). LM/SEM demonstrated the PRP had less aggregation/activation over time within the cosmetic base and that refrigeration is superior to room-temperature storage thus delaying full platelet degranulation. The in vivo clinical study demonstrated parity between 20ml and 60ml PRP in terms of clinical efficacy. CONCLUSION: Platelets remain viable for up to 90 days in a refrigerated cosmetic vehicle with demonstrated topical clinical PRP facial benefits. PRP kits of 20ml and 60ml volumes for topical PRP are equally efficacious. J Drugs Dermatol. 2020;19(12): doi:10.36849/JDD.2020.5495.

Platelet Concentrates in Musculoskeletal Medicine.

Platelet concentrates (PCs), mostly represented by platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are autologous biological blood-derived products that may combine plasma/platelet-derived bioactive components, together with fibrin-forming protein able to create a natural three-dimensional scaffold. These types of products are safely used in clinical applications due to the autologous-derived source and the minimally invasive application procedure. In this narrative review, we focus on three main topics concerning the use of platelet concentrate for treating musculoskeletal conditions: (a) the different procedures to prepare PCs, (b) the composition of PCs that is related to the type of methodological procedure adopted and (c) the clinical application in musculoskeletal medicine, efficacy and main limits of the different studies.

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.

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.

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.

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.

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.

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.

Preliminary observations of a new approach to tissue repair: Peripheral blood mononuclear cells in platelet-rich plasma injected into skin graft area.

Our purpose was accelerating the physiologic wound healing, stimulating tissue regeneration and the reparative tissue processes in resistant skin ulcers as in a case of an erosive lichen planus of the soles and after a surgical treatment as for severe Darier disease. The challenge was to establish an effective therapy to enhance tissue healing by the injection of a mixture of peripheral blood mononuclear cells (PB-MNCs) and platelet-rich plasma (PRP) into a skin autograft area. This new perioperative biotechnological approach enriches PRP with the effects of PB-MNCs. It offers a novel advanced strategy that could become an ideal biologic blood-derived therapy, whose components are entirely autologous and produced by a protocol independent by the operator.

The use of platelet-rich plasma (PRP) in the treatment of gastrocnemius strains: a retrospective observational study.

The aim of the present retrospective observational study was to evaluate the time of functional recovery following a specific combined therapeutic approach characterized by an active exercise therapy carried out immediately after Platelet-rich plasma (PRP) injections for the treatment of the muscular lesion of the distal musculotendinous junction of the gastrocnemius medial head.Medical records of 31 subjects treated with three PRP intra-lesional ultrasound guided injections and 30 patients treated with the standard therapeutic approach (control group) were analyzed. Both groups followed the same rehabilitation therapy. Patients in the control group were able to start active exercise with a significant delay when compared to the PRP treated subjects: 17 ± 7.2 days and 9 ± 3.8 days (p = 0.0001), respectively. This delay was mainly due to the persistence of pain in the subjects in the control group. The time necessary to return to walk without pain was significantly shorter in the PRP treated group: 24.27 ± 12.36 days versus 52.4 ± 20.03 days in the control group (p < 0.001) as well as the time needed to fully return to practice the previous sport activity: 53.33 ± 27.74 days versus 119.3 ± 43.87 days in the control group (p < 0.001).The present study showed that ultrasound guided delivery of PRP into the site of muscle injury has to be considered a valid therapeutic approach with the potentiality of significantly reduce time and costs for reaching a complete functional recovery.

The contribution of leucocytes to the antimicrobial activity of platelet-rich plasma preparations: A systematic review.

The infection of a wound is one of the major contributors to delays in healing and tissue regeneration. As multi-drug resistance to antibiotics is becoming a serious threat, research in this field has focused on finding new agents and strategies to fight infection and additionally to reduce healing times. The topical use of autologous Platelet Rich Plasma (PRP) as a biological accelerator of the healing process, has been safely used as a form of treatment for wounds since the 1990s. Although the presence or absence of leucocytes in PRP preparation was previously neglected, in the last decade more attention has been paid to their role and several studies have been conducted to explore both their immuno-metabolic effects and their antimicrobial properties. In this review, we aim to summarise the literature on the contribution of leucocytes included in PRP preparations in terms of their antimicrobial properties. This should help to inform clinical practice and additional research in this promising field.

Bone marrow concentrate and platelet-rich plasma differ in cell distribution and interleukin 1 receptor antagonist protein concentration.

PURPOSE: Bone marrow concentrate (BMC) and platelet-rich plasma (PRP) are used extensively in regenerative medicine. The aim of this study was to determine differences in the cellular composition and cytokine concentrations of BMC and PRP and to compare two commercial BMC systems in the same patient cohort. METHODS: Patients (29) undergoing orthopaedic surgery were enrolled. Bone marrow aspirate (BMA) was processed to generate BMC from two commercial systems (BMC-A and BMC-B). Blood was obtained to make PRP utilizing the same system as BMC-A. Bone marrow-derived samples were cultured to measure colony-forming units, and flow cytometry was performed to assess mesenchymal stem cell (MSC) markers. Cellular concentrations were assessed for all samples. Catabolic cytokines and growth factors important for cartilage repair were measured using multiplex ELISA. RESULTS: Colony-forming units were increased in both BMCs compared to BMA (p < 0.0001). Surface markers were consistent with MSCs. Platelet counts were not significantly different between BMC-A and PRP, but there were differences in leucocyte concentrations. TGF-ß1 and PDGF were not different between BMC-A and PRP. IL-1ra concentrations were greater (p = 0.0018) in BMC-A samples (13,432 pg/mL) than in PRP (588 pg/mL). The IL-1ra/IL-1ß ratio in all BMC samples was above the value reported to inhibit IL-1ß. CONCLUSIONS: The bioactive factors examined in this study have differing clinical effects on musculoskeletal tissue. Differences in the cellular and cytokine composition between PRP and BMC and between BMC systems should be taken into consideration by the clinician when choosing a biologic for therapeutic application. LEVEL OF EVIDENCE: Clinical, Level II.

Overcoming the bottleneck of platelet lysate supply in large-scale clinical expansion of adipose-derived stem cells: A comparison of fresh versus three types of platelet lysates from outdated buffy coat-derived platelet concentrates.

BACKGROUND: Platelet lysates (PL) represent a promising replacement for xenogenic growth supplement for adipose-derived stem cell (ASC) expansions. However, fresh platelets from human blood donors are not clinically feasible for large-scale cell expansion based on their limited supply. Therefore, we tested PLs prepared via three methods from outdated buffy coat-derived platelet concentrates (PCs) to establish an efficient and feasible expansion of ASCs for clinical use. METHODS: PLs were prepared by the freeze-thaw method from freshly drawn platelets or from outdated buffy coat-derived PCs stored in the platelet additive solution, InterSol. Three types of PLs were prepared from outdated PCs with platelets suspended in either (1) InterSol (not manipulated), (2) InterSol + supplemented with plasma or (3) plasma alone (InterSol removed). Using these PLs, we compared ASC population doubling time, cell yield, differentiation potential and cell surface markers. Gene expression profiles were analyzed using microarray assays, and growth factor concentrations in the cell culture medium were measured using enzyme-linked immunosorbent assay (ELISA). RESULTS: Of the three PL compositions produced from outdated PCs, removal of Intersol and resuspension in plasma prior to the first freezing process was overall the best. This specific outdated PL induced ASC growth kinetics, surface markers, plastic adherence and differentiation potentials comparable with PL from fresh platelets. ASCs expanded in PL from fresh versus outdated PCs exhibited different expressions of 17 overlapping genes, of which 10 were involved in cellular proliferation, although not significantly reflected by cell growth. Only minor differences in growth factor turnover were observed. CONCLUSION: PLs from outdated platelets may be an efficient and reliable source of human growth supplement allowing for large-scale ASC expansion for clinical use.