The Healing Potential of Platelet‐Rich Plasma: Advances in Preparation Methods, Biomedical Applications, and Emerging Challenges

Background Platelet-rich plasma (PRP) and its derivatives are used in several aesthetic, dental, and musculoskeletal procedures. Their efficacy is primarily due to the release of various growth factors (GF), interleukins, cytokines, and white blood cells. However, the PRP preparation methods are highly variable, and studies lack consistency in reporting complete procedures to prepare PRP and characterize PRP and its derivatives. Also, all the tissue-specific (in vivo and in vitro) interactions and functional properties of the various derivatives/factors of the PRP have not been taken into consideration by any study so far. This creates a potential space for further standardization of the PRP preparation methods and customization of PRP/PRP derivatives targeted at tissue-specific/pathology specific requirements that would enable efficacious and widely acceptable usage of PRP as main therapy, rather than being used as adjuvant therapy. The main objective of our study was to investigate the variability in PRP preparation methods and to analyze their efficacy and reliability. Method This study considered articles published in the last 5 years, highlighting the variability in their PRP preparation methods and characterization of PRP. Following the PRISMA protocol, we selected 13 articles for the study. The selected articles were assessed using NHLBI quality assessment tool. Results We noted differences in (1) approaches to producing PRP, (2) extent of characterization of PRP, (3) small scale and large-scale preparation methods, (4) in vitro and in vivo studies. Conclusion We identified two studies describing the procedures which are simple, reproducible, economical, provide a good yield of platelets, and therefore can be considered methods for further tissue-specific and pathology-specific standardizations of PRP and its derivatives. We recommend further randomized studies to understand the full therapeutic potential of the constituents of PRP and its derivatives.

Background: Platelet-rich plasma (PRP) refers to an enriched platelet suspension in plasma. In addition to the clinical application of PRP in the context of various orthopedic diseases and beyond, PRP and platelet lysate (PL) have been in focus in the field of tissue engineering. In this review, we discuss the application of PRP as a cell culture supplement and as part of tissue engineering strategies, particularly emphasizing current hurdles and ambiguities regarding the efficacy of PRP in these approaches. Summary: As a putative autologous replacement for animal-derived supplements such as fetal calf serum (FCS), PRP has been applied as cell culture supplement for the expansion of stem and progenitor cells for tissue engineering applications and cell therapies. Attributed to the high content of growth factors in platelets, PRP has been shown to promote cell growth, which was mostly superior to standard cultures supplemented with FCS, while the differentiation capacity of progenitor cells seems not to be affected. However, it was also suggested that cultivation of cells with PRP significantly alters the protein expression profile in cells in comparison to FCS, indicating that the influence of PRP on cell behavior should be thoroughly investigated. Moreover, different PRP preparation methods and donor variations have to be considered for the use of PRP under good manufacturing practice conditions. PRP has been used for various tissue engineering applications in the context of bone, cartilage, skin, and soft tissue repair, where most studies were conducted in the field of bone tissue engineering. These approaches take either advantage of the release of chemoattractive, angiogenic, proliferative, and putatively pro-regenerative growth factors from PRP, and/or the hydrogel properties of activated PRP, making it suitable as a cell delivery vehicle. In many of these studies, PRP is combined with biomaterials, cells, and in some cases recombinant growth factors. Although the experimental design often does not allow conclusions on the pro-regenerative effect of PRP itself, most publications report beneficial effects if PRP is added to the tissue-engineered construct. Furthermore, it was demonstrated that the release of growth factors from PRP may be tailored and controlled when PRP is combined with materials able to capture growth factors. Key Messages: Platelet-derived preparations such as PRP and PL represent a promising source of autologous growth factors, which may be applied as cell culture supplement or to promote regeneration in tissue-engineered constructs. Furthermore, activated PRP is a promising candidate as an autologous cell carrier. However, the studies investigating PRP in these contexts often show conflicting results, which most likely can be attributed to the lack of standardized preparation methods, particularly with regard to the platelet content and donor variation of PRP. Ultimately, the use of PRP has to be tailored for the individual application.

Leukocyte concentration and composition in platelet-rich plasma (PRP) influences the growth factor and protease concentrations.

Background:Despite its increasing use in the management of musculoskeletal conditions, questions remain regarding the preparation methods of platelet-rich plasma (PRP) and its clinical applications for intra-articular hip disorders, including femoroacetabular impingement syndrome (FAIS), labral pathology, and osteoarthritis (OA).Purpose:To systematically review and assess the preparation methods and clinical outcomes from randomized clinical trials (RCTs) on the use of PRP for intra-articular hip disorders.Study Design:Systematic review; Level of evidence, 2.Methods:A systematic review in accordance with the 2009 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was performed in September 2019. The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, PubMed, Ovid Medline, and Embase were queried for studies regarding the use of PRP to treat intra-articular hip disorders. Qualifying articles were English-language RCTs describing the use of PRP for intra-articular hip disorders, either as standalone treatment or surgical augmentation. Two authors independently assessed article eligibility. Data pertaining to patient characteristics, indication for treatment, PRP preparation method, follow-up period, and clinical outcomes were extracted. Study results were qualitatively reported and quantitatively compared using meta-analysis when appropriate.Results:Seven RCTs met inclusion criteria. Four studies described the use of PRP for hip OA and 3 utilized PRP at arthroscopy for FAIS and labral tears. Outcomes after PRP for OA demonstrated improvement in validated patient-reported outcome measures for up to 1 year; however, pooled effect sizes found no statistically significant difference between PRP and hyaluronic acid (HA) regarding pain visual analog scale scores at short-term (≤2 months; P = .27), midterm (4-6 months; P = .85), or long-term (1 year; P = .42) follow-up. When injected at arthroscopy, 1 study reported improved outcomes, 1 reported no difference in outcomes, and 1 reported worse outcomes compared with controls. The meta-analysis demonstrated no statistically significant difference on the modified Harris Hip Score (mHHS) between PRP and control cohorts at a minimum 1-year follow-up. There were considerable deficiencies and heterogeneity in the reporting of PRP preparation methods for both indications.Conclusion:Treatment of OA with PRP demonstrated reductions in pain and improved patient-reported outcomes for up to 1 year. However, there was no statistically significant difference between PRP and HA in pain reduction. Likewise, for FAIS and labral surgery there was no statistically significant difference in mHHS outcomes between patients treated with PRP and controls. Given the limited number of studies and variability in PRP preparations, additional high-quality randomized trials are warranted.

Implementation of a closed platelet-rich-plasma preparation method using the local blood bank infrastructure at the Principality of Asturias (Spain): Back to basic methodology and a demographics perspective after 1 year

Background: platelets are a rich source of various growth factors and hence platelet rich plasma (PRP) is being used therapeutically in the fi eld of dermatology, orthopaedics and dentistry with promising results. However, methods of preparation of PRP vary with many commercial kits also available. Scoring systems like DEPA score, PAW system and sports medicine criteria score help in determining the quality of the fi nal product and guide therapy. Here we test a simple two step method for preparation of PRP and score it according to the abovementioned criteria while comparing it with the commercial kits analysed in literature. Methods: 10 ml whole blood was collected in 1.5 ml ACD solution from 100 healthy willing participants and analysed for platelet concentration. Sample was then centrifuged at 1600 rpm X 4 minutes in a calibrated laboratory centrifuge and supernatant was collected in a sterile tube using a sterile syringe. The supernatant was further concentrated for platelets by centrifuging at 3600 rpm X 10 minutes to form a platelet pellet at the bottom. All but 1 ml supernatant (Platelet defi cient plasma) was discarded and the platelet pellet was suspended again to form platelet rich plasma. Platelet count was estimated in this sample as done with the whole blood sample. The results were compared and analysed using statistical methods to determine the effi cacy of concentrating platelets by this method. Results: The tested method gave a fi nal concentration of more than four times the baseline concentration with approximately 30% effi ciency of capture and 80% purity. This was comparable to majority of the commercial systems tested in literature at a fraction of the cost. The scores according to various classifi cation systems were determined and reported. Conclusion: Every platelet rich plasma prepared for therapeutic purposes should be classifi ed according to any of the available scoring systems to determine its suitability for the purpose and to maintain uniformity in the quality of the product. The proposed two step method of preparation yields satisfactory quality of PRP by utilizing services of a basic laboratory at a fraction of the cost of commercial systems thereby enabling smaller medical institutions to utilize PRP therapy.

This comprehensive review delves into the emerging role of platelet-rich plasma (PRP) in accelerating bone healing. PRP, a blood-derived product rich in platelets and growth factors, has garnered attention for its regenerative potential. The review begins by defining PRP and providing a historical background, highlighting its significance in expediting bone healing. PRP's composition and preparation methods, including centrifugation techniques and commercial kits, are explored. Mechanistically, PRP operates by releasing growth factors, chemotaxis, and angiogenesis, elucidating its cellular effects. Applications in fracture healing and orthopaedic surgeries, such as joint arthroplasty and spinal fusion, are discussed, emphasising the promising outcomes in clinical trials. Safety considerations, patient selection criteria, and the need for PRP preparation and application standardisation are underscored. The review outlines ongoing research trends, potential technological advancements, and unexplored areas in paediatric applications and inflammatory bone disorders. The implications for clinical practice involve informed decision-making, optimised protocols, and interdisciplinary collaboration. In conclusion, the future of PRP in bone healing holds exciting prospects, with the potential for precision medicine, integration with emerging therapies, expanded applications, and enhanced technological innovations shaping its trajectory in orthopaedics and regenerative medicine.

Greater trochanteric pain syndrome (GTPS) is a prevalent musculoskeletal condition characterised by lateral hip pain and reduced function. Platelet-rich plasma (PRP) injections have gained attention as a potential treatment due to their regenerative properties. However, variability in PRP preparation methods and insufficient standardisation in the literature complicate the evaluation of its efficacy and reproducibility. This systematic review aims to assess the level of standardisation in PRP injection protocols for GTPS, focusing on preparation methods, injection techniques, and reported outcomes. A systematic review was conducted using comprehensive searches of major databases. Inclusion criteria targeted randomised controlled trials (RCTs) evaluating PRP for GTPS in adults. Four eligible RCTs were identified, and data were extracted on PRP preparation methods, injection protocols, and reported outcomes. The risk of bias was assessed using the Cochrane Risk of Bias 2 (RoB 2) tool. The included studies demonstrated significant heterogeneity in PRP preparation methods, including centrifugation speeds (1,100 gravitational force (g) to 3,850 revolutions per minute (rpm)), blood volumes (25-54 mL), and platelet concentrations (9.23 × 10⁹/L to 1232 × 10⁹/L). Injection sites varied from the gluteal tendons to the trochanteric bursa, with volumes ranging from 4 mL to 7 mL. Only one study conducted ultrasound-guided injections into the tendon. Despite the variability, two studies reported significant improvements in pain and function, while two found no difference compared to the control. This review highlights the lack of standardisation in PRP preparation and injection protocols for GTPS. Standardised guidelines are urgently needed to improve comparability across studies and optimise clinical outcomes. Future research should establish consensus on PRP preparation, classification, and reporting standards to advance its clinical application.

We would like to thank Prof. Dhillon and colleagues for the opportunity to revisit and explore some interesting and very controversial aspects of this innovative biological treatment approach. In a previous study [5] and in the subsequent analysis ‘‘platelet-rich plasma intra-articular knee injections for the treatment of degenerative cartilage lesions and osteoarthritis’’ [3] cited by Dhillon et al., we aimed to analyze our preliminary results with the use of intra-articular knee injections of platelet-rich plasma (PRP) as minimally invasive treatment for knee degenerative pathology. Our findings suggested the potential to reduce pain and improve both knee function and quality of life with short-term efficacy, especially in younger patients with chondral degenerative lesions or early osteoarthritis (OA). First of all, we would like to answer the observations made about the PRP preparation method. Our procedure involved a 150-ml venous blood sample, which was centrifuged twice to produce a 20-ml unit of PRP. The PRP was then divided into 4 small units of 5 ml each. All of the open procedures were performed in an A-class sterile hood. As correctly underlined, once prepared, the first PRP sample was injected within 4–6 h. The remaining samples were immediately stored at -30 C, in order to avoid the risks of bacterial proliferation and accumulation of pyrogenic cytokines, and towed after 3 and 6 weeks for the other cycle injections. We disagree with the doubts about the storing procedure. Freezing them gives us the time to proceed with the quality analysis. This has to be considered as an advantage, not a disadvantage, with respect to the open procedures for fresh PRP application. In fact, now in our clinical practice, we are also freezing the first sample; this delays the first injection but increases the safety procedure, ensuring a controlled not contaminated intraarticular delivery of the product. The alteration of the morphology and decrease in platelet functional properties, which includes degranulation of alpha-granules, after storing platelets in freezing conditions, is well known. On the contrary, there are no data on the effect of freezing on the clinical results of platelet injections and freeze-thawing is even one of the methods used for releasing intracellular GFs [2, 9]. Some studies, as well as some of our preliminary unpublished data, show a not significant influence of freezing on GF release, and frozen platelets have also been used by other authors [2, 8]. Regarding methods that increase the storage life of platelets in freezing conditions, such as the mentioned dimethylsulfoxide (DMSO), they involve further platelet manipulation and carry some risks, too (not excluding severe adverse events such as neurological toxicity), and removing it before patient administration also means losing cells and bioactive molecules [4]. Having freshly harvested PRP might preserve all the platelet functions better, but currently the data are still controversial and we cannot say that freeze-thawing adversely affects their properties to the point of impairing their clinical efficacy. Cellularity is another debated aspect of not secondary importance when evaluating PRP properties and the results obtained with its application. In fact, not only platelets but also leukocytes, monocytes, macrophages, and mast cells are contained in many platelet concentrates. Some authors define PRP as only platelets and attribute better results to leukocyte depletion, because of the deleterious effects of proteases and reactive oxygen released from white cells; G. Filardo E. Kon (&) M. Marcacci Biomechanics Laboratory–III Clinic, Rizzoli Orthopaedic Institute, Bologna, Italy e-mail: e.kon@biomec.ior.it

Using systematic review methodology, we endeavored to answer the following questions concerning the treatment of osteochondral pathology: (1) what pathologies have been treated in vivo with the use of platelet-rich plasma (PRP); (2) what methods of PRP preparation and delivery have been reported; (3) what assessment tools and comparison group have been used to assess its effectiveness; and (4) what are the clinical outcomes of its use. A systematic literature search was performed of the OVID, EMBASE, and Evidence Based Medicine Reviews databases to identify all studies published up to October 2012 that assessed clinical outcomes of the use of PRP for the treatment of chondral and osteochondral pathology, excluding those including concomitant management of acute fractures or ligament reconstruction. The included studies were reviewed and the following data were extracted and tabulated: study authors' year and journal, study design and level of evidence, pathology treated, methods of PRP preparation and delivery, and clinical outcome scores. Ten studies were included in the final analysis. The majority of studies assessed the use of PRP in the treatment of degenerative osteoarthritis of the knee or hip (representing 570 of a total of 662 joints). The majority of patients were treated with intra-articular injections, whereas 2 studies used PRP as an adjunct to surgical treatment. Significant improvements in joint-specific clinical scores (7 of 8 studies), general health scores (4 of 4 studies), and pain scores (4 of 6 studies) compared with baseline were reported up to 6-month follow-up, but few studies provided longer-term data. No studies reported worse scores compared with baseline at final follow-up. Three of 4 comparative studies reported significantly better clinical and/or pain scores when compared with hyaluronic acid injections at similar follow-up times. Currently, there is a paucity of data supporting the use of PRP for the management of focal traumatic osteochondral defects. There is limited evidence suggesting short-term clinical benefits with the use of PRP for symptomatic osteoarthritis of the knee, but the studies published to date are of poor quality and at high risk for bias. Further high-quality comparative studies with longer follow-up are needed to ascertain whether PRP is beneficial, either alone or as an adjunct to surgical procedures, in the management of articular cartilage pathology.

Objective.Platelet Rich Plasma (PRP) is an autologous preparation currently used in oral and maxillofacial reconstructive surgery.Blood collection and preparation of platelet concentrates may lead to platelet activation and the premature loss of their granular load.In this study, we have analyzed the quality of the PRP obtained from a small volume of whole blood through a double centrifugation technique, so called "tube method".Design.We obtained 50 ml of whole blood from 45 patients and centrifuged at 200 g for 10 minutes.The plasma and buffy-coat were collected and we then centrifuged at 700g for 15 minutes.The pellet was resuspended after discarding 2/3 of the plasma.The platelet concentration, platelet activation and the functional response to thrombin were analyzed in these samples.Results.By using this method of PRP preparation, we obtained a 364 ± 177% increase in platelet concentration in comparison with whole blood levels.Platelet activation, measured by flow cytometry analysis of CD62 expression, was of 2.7% in unprocessed blood and 3.6% in fresh PRP.This figure increased to 16% in PRP samples after overnight storage at room temperature.A percentage of 96% of platelets showed activation in PRP samples after thrombin stimulation.Conclusion.Our results show that platelets contained in PRP concentrates obtained by this method are not significantly activated.A good functional platelet reserve is preserved through the procedure, since platelets maintained a satisfactory response to thrombin after PRP preparation.

To summarize the research progress of platelet-rich plasma (PRP) for the treatment of discogenic low back pain (DLBP). The literature on the treatment of DLBP with PRP was extensively reviewed, and the classification, treatment mechanism, in vitro and in vivo experiments and clinical trial progress of PRP were summarized. According to the PRP composition, preparation methods, and physicochemical properties, there are five commonly used PRP classification systems at present. PRP is involved in delaying or reversing the progress of disc degeneration and pain control by promoting the regeneration of nucleus pulposus cells, increasing the synthesis of extracellular matrix, and regulating the internal microenvironment of degenerative intervertebral disc. Although several in vitro and in vivo studies have confirmed that PRP can promote disc regeneration and repair, significantly relieve pain, and even improve the mobility of DLBP patients. But the contrary conclusion has been reached in a few studies, and there are limitations to the application of PRP. Current studies have confirmed the effectiveness and safety of PRP in the treatment of DLBP and intervertebral disc degeneration, as well as the advantages of PRP in terms of ease of extraction and preparation, low immunological rejection, high regenerative and repair capacity, and the ability to compensate for the shortcomings of traditional treatment modalities. However, relevant studies are still needed to further optimize PRP preparation methods, unify systematic classification guidelines, and clarify its long-term effectiveness.

Thin endometrium (TE) is a significant limiting factor for successful in vitro fertilization (IVF) and embryo transfer (ET), often resulting in poor pregnancy outcomes. Current therapeutic options remain limited and inconsistent in efficacy. This review aims to comprehensively evaluate the clinical potential of platelet-rich plasma (PRP) therapy as an emerging treatment to improve endometrial thickness and fertility outcomes in patients with TE. A systematic analysis of recent studies was conducted to summarize advancements in PRP application for TE. This includes evaluating PRP preparation techniques, treatment protocols, and reported clinical outcomes. Mechanistic insights into how PRP promotes endometrial regeneration through growth factors and angiogenesis were also explored. Evidence from current literature suggests that intrauterine infusion of PRP may enhance endometrial thickness and improve implantation and pregnancy rates in women with refractory TE. However, variations in PRP preparation methods and treatment protocols limit the comparability of results. Safety profiles appear favorable, with few reported adverse events. PRP therapy holds promise as a regenerative approach for the treatment of TE. Nonetheless, the lack of standardized protocols and robust randomized controlled trials necessitates further research. Establishing consensus on preparation methods and treatment timing will be crucial for translating PRP therapy into routine clinical practice.

Platelet-rich plasma (PRP) has emerged as a promising therapeutic approach in regenerative medicine. It contains various growth factors and bioactive molecules that play pivotal roles in tissue repair, regeneration, and inflammation modulation. This comprehensive narrative review delves into the therapeutic potential of PRP in experimental goat and sheep research, exploring recent advancements, challenges, and future prospects in the field. PRP has been explored for its application in musculoskeletal injuries, wound healing, and orthopedic conditions. Studies have demonstrated the ability of PRP to accelerate tissue healing, reduce inflammation, and improve the overall quality of healing. Recent advancements in PRP technology have led to the development of novel formulations and delivery methods to enhance its therapeutic efficacy. PRP has shown promise in tendon and ligament injuries, osteoarthritis, and bone fractures in experimental goat and sheep research. Despite these advancements, several challenges and opportunities exist to harness the full therapeutic potential of PRP in regenerative medicine. Standardizing PRP preparation protocols, including blood collection techniques, centrifugation parameters, and activation methods, is essential to ensure consistency and reproducibility of the findings. Moreover, further research is needed to elucidate the optimal dosing, frequency, and timing of PRP administration for different clinical indications. Research conducted in goat and sheep models provides evidence supporting the translational potential of PRP in tissue engineering and regenerative medicine. By harnessing the regenerative properties of PRP and leveraging insights from preclinical studies, researchers can develop innovative therapeutic strategies to address unmet clinical needs and improve patient outcomes in diverse medical specialties.

<h3>Introduction and history</h3> While regenerative medicine may seem like a novel intervention in the chronic pain armamentarium, its evolution and in a sense its definition has been intricately related to...