Optimisation of platelet concentrates therapy: Composition, localisation, and duration of action

Do autologous platelet concentrates (APCs) have a role in intra-oral bone regeneration? A critical review of clinical guidelines on decision-making process

In the past decades, personalized regenerative medicine has gained increased attention. Autologous platelet concentrates (APCs) such as PRP, PRGF, and L-PRF, all serving as a source of a large variety of cells and growth factors that participate in hard and soft tissue healing and regeneration, could play a significant role in regenerative periodontal procedures. This narrative review evaluated the relative impact of APCs in alveolar ridge preservation, sinus floor augmentation, and the regeneration of bony craters around teeth, both as a single substitute or in combination with a xenograft. L-PRF has a significant beneficial effect on alveolar ridge preservation (bone quality). The data for PRGF are less convincing, and PRP is controversial. L-PRF can successfully be used as a single substitute during transcrestal (≥3.5 mm bone gain) as well as 1-stage lateral window sinus floor elevation (>5 mm bone gain). For PRGF and especially PRP the data are very scarce. In the treatment of bony craters around teeth, during open flap debridement, L-PRF as a single substitute showed significant adjunctive benefits (e.g., >PPD reduction, >CAL gain, >crater depth reduction). The data for PRP and PRGF were non-conclusive. Adding PRP or L-PRF to a xenograft during OFD resulted in additional improvements (>PPD reduction, >CAL gain, >bone fill), for PRGF no data were found. Autologous platelet concentrates demonstrated to enhance bone and soft tissue healing in periodontal regenerative procedures. The data for L-PRF were most convincing. L-PRF also has the advantage of a greater simplicity of production, and its 100% autologous character.

Platelet-rich plasma: a comparative and economical therapy for wound healing and tissue regeneration

Rise in the incidences of chronic degenerative diseases with aging makes wound care a socio-economic burden and unceasingly necessitates a novel, economical, and efficient wound healing treatment. Platelets have a crucial role in hemostasis and thrombosis by modulating distinct mechanistic phases of wound healing, such as promoting and stabilizing the clot. Platelet-rich plasma (PRP) contains a high concentration of platelets than naïve plasma and has an autologous origin with no immunogenic adverse reactions. As a consequence, PRP has gained significant attention as a therapeutic to augment the healing process. Since the past few decades, a robust volume of research and clinical trials have been performed to exploit extensive role of PRP in wound healing/tissue regeneration. Despite these rigorous studies and their application in diversified medical fields, efficacy of PRP-based therapies is continuously questioned owing to the paucity of large samplesizes, controlled clinical trials, and standard protocols. This review systematically delineates the process of wound healing and involvement of platelets in tissue repair mechanisms. Additionally, emphasis is laid on PRP, its preparation methods, handling, classification,application in wound healing, and PRP as regenerative therapeutics combined with biomaterials and mesenchymal stem cells (MSCs).

Platelet-Rich Plasma in the Treatment of Facet Mediated Low Back Pain: A Comprehensive Review

Background

Facet-mediated pain is a major cause of low back pain and as a result, is a significant cause of morbidity, including disability and reduced functionality.

Setting

The present investigation involved a PubMed literature review between June 1, and 2021-January 1, 2022.

Methods

We systematically reviewed was carried Pubmed using the search terms "platelet-rich plasma", "inflammatory mediators", "facet arthropathy", "axial back pain", and "leukoreduction". Data extraction and quality assessment were performed by 3 independent reviewers. Out of the studies analyzed 2 were retrospective, while 1 was a prospective study.

Results

PRP injections for facet mediated or modulated pain are an alternative to conventional pharmacotherapies and interventional injections/radiofrequency. There are limited numbers of studies in world literature at present.

Limitations

Small number of articles in the world literature and small numbers of patients in those published studies.

Conclusions

At present, there are limited studies in the literature; however, larger well-designed studies are warranted to precisely understand efficacy, potential side effects and best practice techniques for PRP injections for facet mediated or modulated pain.

Adipose tissue as a source of growth factors to promote wound healing: a human study of skin graft donor sites

Objective:

In the microenvironment of wound sites, naturally occurring growth factors are crucial for cell migration, opsonisation, chemotaxis, differentiation and angiogenesis. Exogenous growth factors, such as platelet-rich plasma (PRP) and adipose tissue, also improve healing.

Method:

In the present within-subject study, we described the effects of PRP and adipose tissue extract (ATE) on skin graft donor site wound healing in patients requiring split-thickness skin grafts. Each patient, having at least two donor sites, received both control (no growth factor) and experimental (PRP or ATE) treatments. Wounds were evaluated on days 5, 7, 10, 15, 30 and 60. Digital photography and spectral images were used to analyse haemoglobin and melanin content, and re-epithelialisation area. Pain was assessed by visual analogue scale. Scar characteristics were scored on days 30 and 60. Biomaterial samples were analysed for growth factor and protein content.

Results:

The study included 24 patients (18 male and six female; mean age: 59.1 years). PRP was topically applied to wounds in 11 patients (13 donor sites) and ATE in 13 patients (15 sites). ATE-treated donor sites exhibited significantly accelerated wound re-epithelialisation on days 5 and 7 compared with control sites (p=0.003 and 0.04, respectively). PRP accelerated healing on day 7 compared with control sites (p=0.001). Additionally, the application of ATE improved scar quality on days 30 and 60 (p=0.0005 and 0.02, respectively). Pain scores did not differ significantly between treatments.

Conclusion:

In this study, both growth factor sources stimulated wound healing. ATE is an alternative source of growth factors that promote early wound healing and improve scar quality.

Clinical Response After Treatment of Knee Osteoarthritis With a Standardized, Closed-System, Low-Cost Platelet-Rich Plasma Product: 1-Year Outcomes

Background:

Intra-articular infiltration of platelet-rich plasma (PRP) is an alternative therapeutic option to classic hyaluronic acid for the treatment of symptomatic knee osteoarthritis (KOA). However, variation in preparation methods and quality assessment of PRP makes the study of its real clinical efficacy difficult.

Purpose:

To (1) evaluate the clinical efficacy of a characterized PRP product prepared in a standardized manner and in a closed-system for the treatment of KOA and to (2) evaluate the association of the clinical response to PRP-related variables.

Study Design:

Case series; Level of evidence, 4.

Methods:

We recruited 130 patients with nonoperative KOA and evaluated them for 1 year. PRP was prepared from a donation of autologous blood, obtaining 3 aliquots of approximately 10mL of product, which were frozen, allowing platelet disruption, platelet factor release, and long-term storage, until administration. Patients were treated 3 consecutive times every 4 weeks with an intra-articular PRP knee injection under sterile conditions. Complete blood count was performed on the whole-blood sample and the processed PRP before freezing it, for product quality assessment. Patients were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and basic satisfaction scale at 3 months, 6 months, and 1 year after intervention.

Results:

Quality assessment confirmed a leukocyte-poor PRP product (white blood cell count, 0.09 ± 0.09 × 10⁹/L) with a high platelet purity (platelet count, 630.86 ± 191.75 × 10⁹/L). WOMAC scores improved, and basic satisfaction was achieved in 70% of patients. No adverse events were reported. No correlations were observed between PRP quality parameters and clinical results. PRP complete treatment production costs were €108/US$125 (€36/US$41.6 per injection).

Conclusion:

This standardized PRP production method resulted in improved WOMAC scores at 1 year postoperatively in 70% of patients with KOA. This technique was safe and affordable and ensured consecutive infiltrations with the same product to each patient.

Platelet-Rich Plasma for the Treatment of Degenerative Lumbosacral Stenosis: A Study with Retired Working Dogs

Traditionally, canine degenerative lumbosacral stenosis (DLS) has been defined as a multifactorial syndrome characterized by lumbosacral pain triggered by the compression of the nerve rootlets of the cauda equina. There is still no consensus on the treatment of this condition, probably because there are a plethora of possible causes. In addition to compression, inflammation is a very important factor in the physiopathology of the disorder. Platelet-rich plasma (PRP) consists of an increased concentration of autologous platelets suspended in a small amount of plasma. Platelets are a source of several growth factors. Growth factors were shown to help in wound healing and biological processes, such as chemotaxis, neovascularization and synthesis of extracellular matrix, and growth factors were used to improve soft tissue healing and bone regeneration. PRP also facilitates the restoration of the structural integrity of the affected anatomy. Fourteen dogs diagnosed with DLS were treated with three epidural injections of PRP on days 0, 15 and 45. All dogs showed clinical improvement 3 months after the initial treatment. Gait was also objectively assessed by means of the use of force platform analysis before and after treatment, showing significant improvement. The results show that PRP may provide a good alternative to other nonsurgical treatments, such as prednisolone epidural injection.

Functional repertoire of EV-associated miRNA profiles after lipoprotein depletion via ultracentrifugation and size exclusion chromatography from autologous blood products

Cartilage breakdown, inflammation and pain are hallmark symptoms of osteoarthritis, and autologous blood products such as citrate-anticoagulated platelet-rich plasma (CPRP) or hyperacute serum (hypACT) have been developed as a regenerative approach to rebuild cartilage, inhibit inflammation and reduce pain. However, mechanisms of action of these blood derivatives are still not fully understood, in part due to the large number of components present in these medical products. In addition, the discovery of extracellular vesicles (EVs) and their involvement in intercellular communication mediated by cargo molecules like microRNAs (miRNAs) opened up a whole new level of complexity in understanding blood products. In this study we focused on the development of an isolation protocol for EVs from CPRP and hypACT that can also deplete lipoproteins, which are often co-isolated in EV research due to shared physical properties. Several isolation methods were compared in terms of particle yield from CPRP and hypACT. To gain insights into the functional repertoire conveyed via EV-associated miRNAs, we performed functional enrichment analysis and identified NFκB signaling strongly targeted by CPRP EV miRNAs, whereas hypACT EV miRNAs affect IL6- and TGFβ/SMAD signaling.

Potential of Lyophilized Platelet Concentrates for Craniofacial Tissue Regenerative Therapies

Objective: The use of platelet concentrates (PCs) in oral and maxillofacial surgery, periodontology, and craniofacial surgery has been reported. While PCs provide a rich reservoir of autologous bioactive growth factors for tissue regeneration, their drawbacks include lack of utility for long-term application, low elastic modulus and strength, and limited storage capability. These issues restrict their broader application. This review focuses on the lyophilization of PCs (LPCs) and how this processing approach affects their biological and mechanical properties for application as a bioactive scaffold for craniofacial tissue regeneration. Materials and Methods: A comprehensive search of five electronic databases, including Medline, PubMed, EMBASE, Web of Science, and Scopus, was conducted from 1946 until 2019 using a combination of search terms relating to this topic. Results: Ten manuscripts were identified as being relevant. The use of LPCs was mostly studied in in vitro and in vivo craniofacial bone regeneration models. Notably, one clinical study reported the utility of LPCs for guided bone regeneration prior to dental implant placement. Conclusions: Lyophilization can enhance the inherent characteristics of PCs and extends shelf-life, enable their use in emergency surgery, and improve storage and transportation capabilities. In light of this, further preclinical studies and clinical trials are required, as LPCs offer a potential approach for clinical application in craniofacial tissue regeneration.

Autologous Matrix of Platelet-Rich Fibrin in Wound Care Settings: A Systematic Review of Randomized Clinical Trials

Platelet-rich fibrin (PRF) consists of a matrix that provides the necessary elements for wound healing, acting as a biodegradable scaffold for cell migration, proliferation, and differentiation, in addition to the delivery of growth factors and angiogenesis. This study aims to determine the effectiveness of the autologous PRF in the treatment of wounds of different etiologies. We carried out a systematic review of randomized clinical trials, guided by the recommendations of the Cochrane Collaboration using the following databases: Pubmed/MEDLINE, EMBASE, Web of Science, and CENTRAL. The search strategy resulted in the inclusion of ten studies that evaluated the use of PRF dressings for the healing of acute or chronic wounds of multiple etiologies. Among the 172 participants treated with PRF in wounds of varying etiologies and different segment times, 130 presented favorable events with the use of the intervention. Among the 10 studies included, only two of them did not demonstrate better results than the control group. The studies showed clinical heterogeneity, making it impossible to perform a meta-analysis. The findings do not provide enough evidence to support the routine use of PRF dressings as the first line of treatment for the healing of acute or chronic wounds of different etiologies. There was great variability in the application of the various protocols and the ways to prepare the PRF, resulting in clinical heterogeneity. Therefore, it makes it impossible to synthesize and to collect evidence from different types of studies in the meta-analysis, which affects the results and their proper discussion.

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.

Regenerative Effect of Platelet Concentrates in Oral and Craniofacial Regeneration

Platelet concentrates (PCs) are biological autologous products derived from the patient's whole blood and consist mainly of supraphysiologic concentration of platelets and growth factors (GFs). These GFs have anti-inflammatory and healing enhancing properties. Overall, PCs seem to enhance bone and soft tissue healing in alveolar ridge augmentation, periodontal surgery, socket preservation, implant surgery, endodontic regeneration, sinus augmentation, bisphosphonate related osteonecrosis of the jaw (BRONJ), osteoradionecrosis, closure of oroantral communication (OAC), and oral ulcers. On the other hand, no effect was reported for gingival recession and guided tissue regeneration (GTR) procedures. Also, PCs could reduce pain and inflammatory complications in temporomandibular disorders (TMDs), oral ulcers, and extraction sockets. However, these effects have been clinically inconsistent across the literature. Differences in study designs and types of PCs used with variable concentration of platelets, GFs, and leucocytes, as well as different application forms and techniques could explain these contradictory results. This study aims to review the clinical applications of PCs in oral and craniofacial tissue regeneration and the role of their molecular components in tissue healing.

Platelet-Rich Plasma for the Treatment of Low Back Pain: a Comprehensive Review

PURPOSE OF REVIEW

Back pain is a growing problem worldwide, incurring enormous economic costs and disability. Current treatment modalities often provide adequate relief but fail to address underlying conditions. Regenerative cellular modalities aim to restore anatomical function in degenerative conditions which may cause low back pain. Platelet-rich plasma (PRP) consists of an increased concentration of autologous platelets suspended in a small amount of plasma. PRP can be administered via injection or topically and is prepared using various techniques.

RECENT FINDINGS

While a unifying mechanism of action is not well understood, biochemical and cellular changes involved in inflammation and mechanical structure have been detected in both in vitro and in vivo studies. At a higher level, PRP injection research utilizing animal models and patient data have provided insights into pain relief, chondroprotection, and factors that impact the therapy's efficacy. Recently, a small number of studies have promoted PRP injection as a relatively safe means of treating patients with degenerative disc disease who have failed other means of managing their lower back pain. PRP injections for sacroiliac joint-related pain are not an accepted or common treatment modality; the evidence for their efficacy remains to be seen outside of small RCTs and case reports. A small number of prospective trials have suggested there may be some benefit to using PRP injection in the treatment of pain or functional decline caused by facet joint arthropathy. These commonly used modalities require further study to improve quality of evidence and to investigate the safety and efficacy of PRP injections for various common causes of chronic low back.

Molecular and Cellular Aspects of Socket Healing in the Absence and Presence of Graft Materials and Autologous Platelet Concentrates: a Focused Review

OBJECTIVES

The present manuscript aims to critically detail the physiologic process of socket healing, in the absence or presence of grafting materials or platelet concentrates, addressing the associated molecular and cellular events that culminate in the restoration of the lost tissue architecture and functionality.

MATERIAL AND METHODS

An electronic search in the National Library of Medicine database MEDLINE through its online site PubMed and Web of Science from inception until May 2019 was conducted to identify articles concerning physiologic process of socket healing, in the absence or presence of grafting materials or platelet concentrates. The search was restricted to English language articles without time restriction. Additionally, a hand search was carried out in oral surgery, periodontology and dental implants related journals.

RESULTS

In total, 122 literature sources were obtained and reviewed. The detailed biological events, at the molecular and cellular level, that occur in the alveolus after tooth extraction and socket healing process modulated by grafting materials or autologous platelet concentrates were presented as two entities.

CONCLUSIONS

Tooth extraction initiates a convoluted set of orderly biological events in the alveolus, aiming wound closure and socket healing. The healing process comprises a wide range of events, regulated by the interplay of cytokines, chemokines and growth factors that determine cellular recruitment, proliferation and differentiation in the healing milieu, in a space- and time-dependent choreographic interplay. Additionally, the healing process may further be modulated by the implantation of grafting materials or autologous platelet concentrates within the tooth socket, aiming to enhance the regenerative outcome.

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.

Growth factor release and enhanced encapsulated periodontal stem cells viability by freeze-dried platelet concentrate loaded thermo-sensitive hydrogel for periodontal regeneration

Periodontium regeneration is a highly challenging process as it requires the regeneration of three different tissues simultaneously. The aim of this study was to develop a composite material that can be easily applied and can sufficiently deliver essential growth factors and progenitor cells for periodontal tissue regeneration.

Freeze-dried platelet concentrate (FDPC) was prepared and incorporated in a thermo-sensitive chitosan/β-glycerol phosphate (β-GP) hydrogel at concentrations of 5, 10, or 15 mg/ml. The viscosity of the hydrogels was investigated as the temperature rises from 25 °C to 37 °C and the release kinetics of transforming growth factor (TGF-β1), platelet-derived growth factor (PDGF-BB) and insulin-like growth factor (IGF-1) were investigated at four time points (1 h, 1 day, 1 week, 2 weeks). Periodontal ligament stem cells (PDLSCs) were isolated from human third molars and encapsulated in the different hydrogel groups. Their viability was investigated after 7 days in culture in comparison to standard culture conditions and non FDPC-loaded hydrogel.

Results showed that loading FDPC in the hydrogel lowered the initial viscosity in comparison to the unloaded control group and did not affect the sol-gel transition in any group. All FDPC-loaded hydrogel groups exhibited sustained release of TGF-β1 and PDGF-BB for two weeks with significant difference between the different concentrations. The loading of 10 and 15 mg/ml of FDPC in the hydrogel increased the PDLSCs viability significantly compared to the unloaded hydrogel and was comparable to the standard culture conditions.

Accordingly, it may be concluded that loading FDPC in a chitosan/β-GP hydrogel can offer enhanced injectability, a sustained release of growth factors and increased viability of encapsulated stem cells which can be beneficial in periodontium tissue regeneration.

Platelet Rich Plasma: New Insights for Cutaneous Wound Healing Management

The overall increase of chronic degenerative diseases associated with ageing makes wound care a tremendous socioeconomic burden. Thus, there is a growing need to develop novel wound healing therapies to improve cutaneous wound healing. The use of regenerative therapies is becoming increasingly popular due to the low-invasive procedures needed to apply them. Platelet-rich plasma (PRP) is gaining interest due to its potential to stimulate and accelerate the wound healing process. The cytokines and growth factors forming PRP play a crucial role in the healing process. This article reviews the emerging field of skin wound regenerative therapies with particular emphasis on PRP and the role of growth factors in the wound healing process.