Clinical Application of Platelet-Rich Fibrin in Plastic and Reconstructive Surgery: A Systematic Review

Autologous Platelet-rich Fibrin as a Three-dimensional Structural Scaffold in the Healing of Contracted Orbital Sockets

PURPOSE

Evaluation of platelet-rich fibrin as an adjuvant in surface healing of contracted orbital sockets.

METHODS

Prospective, interventional, and comparative study of 25 patients with moderate to severe contracted sockets conducted over 2 years (February 2020-February 2022). Group 1 underwent a dermis-fat graft with fornix forming sutures supplemented by a platelet-rich fibrin membrane, while group 2 received a dermis-fat graft with fornix forming sutures only. Patients over 18 years were evaluated as per prefixed inclusion and exclusion criteria. Assessments were conducted at 1, 3, and 12 months postsurgery, focusing on wound evaluation, socket epithelialization, postoperative pain, prosthesis rehabilitation, and complications, if any. Wound evaluation and pain intensity were assessed utilizing the wound evaluation score and visual analog scale, respectively. Socket epithelization was documented clinically at every visit.

RESULTS

The study showed a mean age of 38.8 ± 8.8 years, with a 2:1 male-to-female ratio. Group 1 consistently scored higher on wound evaluation score than group 2 at all follow-up points. In group 1, 81.8% achieved a maximum wound evaluation score at 4 weeks and 100% at 3 and 12 months, compared to group 2's 42.8%, 50%, and 57.1%, respectively (p < 0.05). Postoperative contracture occurred in 3 group 2 patients at the final follow-up, with 6 showing unsatisfactory appearance. Group 1 demonstrated significantly lower pain intensity on postoperative day 1 (p = 0.03), and greater epithelization at 4 weeks.

CONCLUSION

platelet-rich fibrin appears to be an effective solution for enhancing wound healing during socket reconstruction, attributed to its sustained release of growth factors and mesenchymal stem cells.

Three Milliliters of Peripheral Blood Is Sufficient for Preparing Liquid Platelet-Rich Fibrin (PRF): An In Vitro Study

Platelet-rich fibrin (PRF) has assumed an important role in supporting tissue regeneration in different fields. To date, the standard protocol for liquid PRF requires at least 10 mL of peripheral blood. The present study aimed to analyze the composition, growth factor release, and effects on the cell proliferation of PRF samples produced using 3 mL vs. 10 mL of peripheral blood in vitro. Peripheral venous blood from six healthy donors was used to prepare liquid PRF using either 3 mL or 10 mL tubes. Three different centrifugation protocols were used according to the low-speed centrifugation concept. The cellular distribution was evaluated using immunohistology and automated cell count. ELISA was used to determine the release of different growth factors (EGF, TGF-β1, and PDGF) and interleukin 8 at different time points. Primary human osteoblasts (pOBs) were cultivated for 7 days using PRF-conditioned media acquired from either 3 mL or 10 mL of peripheral blood. The results showed that 3 mL of peripheral blood is sufficient to produce a liquid PRF concentrate similar to that acquired when using 10 mL blood. The concentrations of platelets and leukocytes were comparable regardless of the initial blood volume (3 mL vs. 10 mL). Similarly, the release of growth factors (EGF, TGF-β1, and PDGF) and interleukin 8 was often comparable in both groups over 7 days. The cultivation of pOBs using PRF-conditioned media showed a similar proliferation rate regardless of the initial blood volume. This proliferation rate was also similar to that of pOBs treated with 20% FBS-conditioned media. These findings validated the use of 3 mL of peripheral blood to generate liquid PRF matrices according to the low-speed centrifugation concept, which may open new application fields for research purposes such as in vivo experiments and clinical applications such as pediatric surgery.

Platelet-rich fibrin improves repair and regeneration of damaged endometrium in rats

Purpose

Intrauterine adhesion (IUA) is the most common cause of uterine infertility. This study aims to evaluate whether platelet-rich fibrin (PRF) treatment can stimulate damaged endometrium regeneration in rats.

Methods

First, hematoxylin and eosin (HE) staining, scanning and transmission electron microscopy, and ELISAs were used to evaluate the microstructure of PRF. Then, mechanical damage was used to establish an IUA rat model. A total of 40 SD female rats were randomized to three groups: PRF transplantation group, IUA group, and sham group. Rats were sacrificed at 3, 7, and 14 days and uteruses were obtained for further analysis. Finally, functional and histological recovery of the damaged endometrium was analyzed by pregnancy test, HE staining, Masson's staining, and immunohistochemistry.

Results

PRF has two distinct zones, platelets and fibrin zone. Long and narrow fibrin fibers interconnected with each other and formed a three-dimensional, flexible, and elastic structure; platelet aggregates were trapped in fibrin fibers, and each platelet is associated with several fibrin fibers. PRF exudates promoted endometrial stromal cell proliferation and migration in vitro. PRF transplantation was beneficial for maintaining uterine structure, promoting endometrial luminal epithelium and endometrial gland regeneration, and decreasing fibrotic areas in vivo.

Conclusion

Intrauterine administration of PRF was demonstrated to be effective in preventing IUA and stimulating damaged endometrium regeneration in rats. This study not only provided a promising method for its potential in endometrial regeneration in women who suffer from uterine infertility but also may prevent IUA after intrauterine surgery in clinical cases.

Can Our Blood Help Ensure Antimicrobial and Anti-Inflammatory Properties in Oral and Maxillofacial Surgery?

In recent decades, the potential of PRF has been extensively studied. The number of studies about PRF has increased three times since the year 2012, but the full spectrum of its fundamental properties, such as antimicrobial and anti-inflammatory activity, is not clearly described. In oral and maxillofacial surgery, PRF is described in alveolar ridge preservation, orthognathic surgery, cleft lip and palate surgery, maxillary sinus augmentation, and dental implant placement as demonstrating favorable results and its clinical advantages. The structural complexity, inhomogeneous nature, and clotting ability of PRF make its antimicrobial effect evaluation complicated. Nevertheless, most of the used antimicrobial testing methods are based on antibacterial agent diffusion ability in culture media. Because the oral and maxillofacial region is the most frequent area of PRF application, its antimicrobial activity evaluation also prevails in the oral microbiome. PRF's biological potential is highly dependent on the specific preparation protocol and methodology used; it should be carefully prepared and kept under proper conditions to keep cellular content alive. PRF's influence on living cells demonstrates a stimulating effect on bone regeneration, and an angiogenetic effect, and it provides anti-inflammatory activity. According to analyzed studies, PRF demonstrated success in oral and maxillofacial surgery in various methods of application. Antibacterial and anti-inflammatory properties were proven by antibacterial activity against different bacterial species, sustained growth factor, sustained release, and cell activity on the material application. Accurately and correctly prepared PRF can ensure antibacterial and anti-inflammatory properties, and it can be a beneficial clinical tool in oral and maxillofacial surgery.

Evolution and Clinical Advances of Platelet-Rich Fibrin in Musculoskeletal Regeneration

Over the past few decades, various forms of platelet concentrates have evolved with significant clinical utility. The newer generation products, including leukocyte-platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF), have shown superior biological properties in musculoskeletal regeneration than the first-generation concentrates, such as platelet-rich plasma (PRP) and plasma rich in growth factors. These newer platelet concentrates have a complete matrix of physiological fibrin that acts as a scaffold with a three-dimensional (3D) architecture. Further, it facilitates intercellular signaling and migration, thereby promoting angiogenic, chondrogenic, and osteogenic activities. A-PRF with higher leukocyte inclusion possesses antimicrobial activity than the first generations. Due to the presence of enormous amounts of growth factors and anti-inflammatory cytokines that are released, A-PRF has the potential to replicate the various physiological and immunological factors of wound healing. In addition, there are more neutrophils, monocytes, and macrophages, all of which secrete essential chemotactic molecules. As a result, both L-PRF and A-PRF are used in the management of musculoskeletal conditions, such as chondral injuries, tendinopathies, tissue regeneration, and other sports-related injuries. In addition to this, its applications have been expanded to include the fields of reconstructive cosmetic surgery, wound healing in diabetic patients, and maxillofacial surgeries.

Autologous platelet concentrates for facial rejuvenation

Autologous platelet concentrates (APCs) are promising therapeutic agents in facial rejuvenation since they are a great source of cytokines, growth factors and other biologically active substances. Obtained from the patient’s blood, they have the advantages of reducing immunological reactions, making the procedure safer, well tolerated, with minimal adverse effects and lower cost. Currently, they are used for facial rejuvenation both in combination with microneedling and in mesotherapy techniques, as well as to treat facial acne scars, melasma and wounds after laser ablative treatments. This review summarizes current knowledge on the use of APCs, ranging from basic concepts related to their composition and mechanisms of action to up-to-date information on their clinical efficacy.

Postoperatif peritoneal adhezyonların önlenmesinde saf zeytinyağı ve PRF’nin etkinliği

Purpose: In this study, we applied platelet rich fibrin (PRF) and pure olive oil on the incision surfaces of rats. We aimed to examine whether PRF may be used safely to prevent peritoneal adhesions. Materials and Methods: Fourty rats were divided into 4 groups (n=8). Eight rats, not included in the study groups, were used to obtain PRF material. Group 1 had no surgical procedure, Group 2 was operated without medication, Group 3 was operated and received 1cc olive oil, Group 4 was operated and received 1 cc PRF. After 21 days, cecum areas were examined histopathologically. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and platelet-derived growth factor (PDGF) levels were measured in serum by ELISA. Results: The adhesion scores and severity of fibrosis in Group 3 and 4 were significantly lower than Group 2. Plasma TNF-α value was significantly higher in Group 2 than Group 4. Plasma PDGF value was significantly higher in Group 2 than Group 3 and 4. Discussion: PRF reduced intestinal adhesion by inhibiting the proliferation of fibroblasts and inflammatory cells, and promoting the proliferation of mesothelial cells. PRF has anti-inflammatory effect and prevented postop adhesions, based mainly on growth factors and cytokines in its content.

Platelet-rich fibrin: An effective chronic wound healing accelerator

BACKGROUND

Platelets are cells that play a central role in wound healing, and they are the main source of the growth factor complex that plays the main role in natural wound healing. It is aimed to present the beneficial effects of topical application of PRF on chronic ulcers that do not respond to standard wound care in cases of chronic ulcers that require a long treatment process and high costs.

MATERIALS AND METHODS

The study included 16 patients between the dates of January 2017 and September 2019. The study was approved by the local ethics board and planned retrospectively.

RESULTS

The mean number of PRF applications in the patients was 4.37 (range: 1-8), while the wounds of 10 patients were completely closed up to the mean number of applications, and at least 50% of the wounds of 4 patients were closed up to the mean number of applications.

DISCUSSION

Choukroun's platelet-rich fibrin may be considered as a 2nd-generation platelet concentration. Its preparation protocol is reported to be highly simple and low-cost.

CONCLUSION

PRF is a safe, practical, easy to use adjuvant treatment method which has a potential for closing chronic wounds.

Comparison of Conventional and Platelet-Rich Plasma-Assisted Fat Grafting: A Systematic Review and Meta-analysis

BACKGROUND

Autologous fat grafting (FG) is a popular technique for soft-tissue augmentation, but the fat survival rate is unpredictable. Platelet-rich plasma (PRP) has emerged as an adjuvant to enhance fat graft survival.

OBJECTIVES

This literature review and meta-analysis aimed to investigate the effect of PRP on the survival rate of fat grafting.

METHODS

A comprehensive systematic literature search was done to identify clinical studies on PRP and fat cotransplantation in PubMed, Cochrane Library, Web of Science, and EMBASE databases up to May 2020. The reference lists of selected articles were reviewed to identify any additional related articles. A meta-analysis was conducted to compare PRP + FG and conventional FG in terms of fat graft survival rate, patient satisfaction rate, and recovery time after surgery.

RESULTS

Eleven studies consisting of 1125 patients were analyzed. Patients were followed up from 3 to 24 months post-FG. The fat survival rate varied from 20.5% to 54.8% in FG alone and from 24.1% to 89.2% in the PRP + FG groups. The survival rate was significantly higher and recovery time was significantly lower in the PRP + FG group than in the FG alone group. However, there was no significant difference in the patient satisfaction rate between the groups.

CONCLUSIONS

This study demonstrates that PRP-enhanced fat transplantation has better efficacy than conventional fat grafting. Further studies are required to provide the optimum concentration of PRP and the long-term efficacy of the technique. There is not enough evidence to compare the rate of complications with PRP and fat cotransplantation and conventional fat grafting.

Ligation of intersphincteric fistula tract (LIFT) with or without injection of platelet-rich plasma (PRP) in management of high trans-sphincteric fistula-in-ano: Short-term outcomes of a prospective, randomized trial

BACKGROUND

Success rate after ligation of the inter-sphincteric fistula tract ranges from 40% to 75%. Platelet-rich plasma is hypothesized to improve healing by slowly releasing growth factors. The objective of the study was to compare the efficacy and outcome of ligation of the inter-sphincteric fistula tract plus platelet-rich plasma local injection versus ligation of the inter-sphincteric fistula tract alone in the management of high trans-sphincteric anal fistula in regards to postoperative pain, time for healing, morbidity, fistula closure rate, recurrence, and quality of life.

METHODS

This was a prospective randomized trial. Patients with trans-sphincteric anal fistulas involving >50% of anal sphincters were included. Patients were randomly assigned to either ligation of the inter-sphincteric fistula tract plus platelet-rich plasma or ligation of the inter-sphincteric fistula tract (49 in each group). The primary endpoints were successful complete fistula closure and duration needed for healing. Secondary endpoints were morbidity, recurrence after 1 year of follow-up, postoperative pain, and quality of life.

RESULTS

Complete primary healing was recorded in 42 patients in the ligation of the inter-sphincteric fistula tract plus platelet-rich plasma group and 32 patients in the ligation of the inter-sphincteric fistula tract group, and the difference was statistically significant (P = .03). The mean time to complete healing after ligation of the inter-sphincteric fistula tract plus platelet-rich plasma was significantly shorter than after ligation of the inter-sphincteric fistula tract alone (15.7 ± 4 days vs 21.6 ± 5.4 days; P = .03). One year after complete healing of anal fistula, recurrence was recorded in 4/42 patients in the ligation of the inter-sphincteric fistula tract plus platelet-rich plasma group and 3/32 patients in the ligation of the inter-sphincteric fistula tract group with no statistically significant difference (P = .99). Patients in the ligation of the inter-sphincteric fistula tract plus platelet-rich plasma group had significantly lower pain scores after both 1 and 7 days. Quality of life and level of happiness were significantly better 1 month after ligation of the inter-sphincteric fistula tract plus platelet-rich plasma.

CONCLUSION

Ligation of the inter-sphincteric fistula tract plus platelet-rich plasma for the treatment of high trans-sphincteric fistula-in-ano is a safe modality with significantly higher successful healing rate, shorter healing time, and less postoperative pain compared with ligation of the inter-sphincteric fistula tract alone. Ligation of the inter-sphincteric fistula tract plus platelet-rich plasma does not improve the rate of recurrence; however, it results in significantly higher short-term quality of life.

Blood-Derived Biomaterial for Catheter-Directed Arterial Embolization

Vascular embolization is a life-saving minimally invasive catheter-based procedure performed to treat bleeding vessels. Through these catheters, numerous metallic coils are often pushed into the bleeding artery to stop the blood flow. While there are numerous drawbacks to coil embolization, physician expertise, availability of these coils, and their costs further limit their use. Here, a novel blood-derived embolic material (BEM) with regenerative properties, that can achieve instant and durable intra-arterial hemostasis regardless of coagulopathy, is developed. In a large animal model of vascular embolization, it is shown that the BEM can be prepared at the point-of-care within 26 min using fresh blood, it can be easily delivered using clinical catheters to embolize renal and iliac arteries, and it can achieve rapid hemostasis in acutely injured vessels. In swine arteries, the BEM increases cellular proliferation, angiogenesis, and connective tissue deposition, suggesting vessel healing and durable vessel occlusion. The BEM has significant advantages over embolic materials used today, making it a promising new tool for embolization.

Considerations for Clinical Use of Concentrated Growth Factor in Maxillofacial Regenerative Medicine

Different strategies have been utilized to facilitate mineralized/soft tissues. Concentrated growth factor (CGF) emerges as a promising biomaterial for regenerative therapy due to high levels of platelets, growth factors, and nucleated cells entrapped in the fibrin scaffold. This review aimed to collect extensive studies on CGF used in maxillofacial regenerative medicine, discussing current obstacles, and expressing some considerations of CGF use. Articles were retrieved systematically without time limitation. In total, 27 human studies were included and separated accordingly. In general, CGF has been most evaluated in implant related therapy and maxillofacial bone regeneration where a majority of articles have revealed favorable outcomes. Little studies have supported the effects on improving probing periodontal depth reductions and clinical attachment level gains for intrabony and furcation defect regeneration. Very little data with high-level evidence was available directly to investigate its effects on the soft tissue regeneration and postoperative complications reduction. The evidence supporting the clinical efficacy of CGF in maxillofacial regenerative medicine is limited. Some conflicting results are worrisome. In addition, the characterization of CGF preparation protocols and CGF's components was not performed in most studies. Further studies should make a consensus on standardized end-product of CGF including characterization of protocols and optimal ratio of CGF' components. Defined algorithms and evidence-based protocols for the clinical use of CGF should be also available.

Injectable platelet-rich fibrin for facial rejuvenation: A prospective, single-center study

BACKGROUND

Autologous platelet-derived preparations have been used in many surgical fields to improve healing outcomes, with benefits reported in several aesthetic indications.

AIMS

This single-center, prospective, uncontrolled study evaluated the efficacy of injectable platelet-rich fibrin (i-PRF) for facial skin rejuvenation using an objective skin analysis system and validated patient-reported outcome measures.

PATIENTS/METHODS

PRF^® PROCESS system technology was used to prepare i-PRP. Eleven healthy female individuals were included in the study and over 3-months received monthly intradermal injections of i-PRF in 3 facial regions: malar areas (1 mL each side), nasolabial fold (0.5 mL each side), and upper lip skin above the vermilion border (1 mL). The efficacy of the procedures was assessed by objective skin analysis (VISIA^® ) and a subjective patient-reported outcome (FACE-Q) assessment at baseline and after 3 months.

RESULTS

A significant improvement in skin surface spots (P = .01) and pores (P = .03) was seen at 3-months follow-up. Other variables, such as skin texture, wrinkles, ultraviolet spots, and porphyrins, showed a numerical improvement. FACE-Q scales that measure satisfaction with appearance all showed a significant improvement from baseline, including satisfaction with skin (P = .002), satisfaction with facial appearance (P = .025), satisfaction with cheeks (P = .001), satisfaction with lower face and jawline (P = .002), and satisfaction with lips (P = .04). No major adverse effects were reported.

CONCLUSIONS

A series of three i-PRF injections resulted in significant rejuvenation of the face skin at 3-month follow-up, as shown by improved skin analysis parameters and patient self-assessment scores.

Cytokine Expression Pattern and Protein-Protein interaction network analysis of Leucocyte Rich Platelet Rich Fibrin and Injectable Form of Platelet Rich Fibrin

PURPOSE

Platelet-rich fibrin (PRF) such as leucocyte-rich PRF (L-PRF) and injectable form of PRF (i-PRF) are widely used in various surgical applications. L-PRF- and i-PRF-derived cytokine variations and functional pathways are still unexplored. The aim of the study was to evaluate the expression pattern of Th1-, Th2-, and Th17-related cytokines by L-PRF and i-PRF under in vitro.

METHODS

Cytokine levels were evaluated using multi-analyte ELISArray kit. Using elevated level of cytokines, the protein-protein interaction and pathway were predicted by computational method.

RESULTS

The expressed cytokine levels were higher in L-PRF than in i-PRF. Specifically in L-PRF, IL8, IL2, IL6, and IL1A were expressed abundantly, whereas IL4, IL10, and IL6 were significantly high in i-PRF. Furthermore, protein-protein interaction (PPI) networks (cytokine-cytokine interactions) and pathway analyses were predicted using higher-order cytokines. PPI networks and gene ontology enrichment analysis showed functional variations between L-PRF and i-PRF. Kyoto Encyclopedia of Gene and Genome pathway analysis found that L-PRF mediates NF-k B signaling, Toll-like receptor signaling (TLR), and MAPK signaling via T-cell receptor signaling pathway. i-PRF is significantly involved in JAK-STAT signaling pathway through upregulation of STAT1.

CONCLUSION

Our study concludes that L-PRF and i-PRF act via different pathways that confirm functional variations between them. Therefore, we speculate that L-PRF may be effective in acute phase of chronic wounds such as in diabetes mellitus and immunocompromised patients whereas i-PRF may have a better outcome in acute wounds.

Platelet-Rich Fibrin Improves Fat Graft Survival Possibly by Promoting Angiogenesis and Adipogenesis, Inhibiting Apoptosis, and Regulating Collagen Production

BACKGROUND

Platelet-rich fibrin (PRF) can promote fat graft survival, but limited data are currently available, and the underlying mechanism of this effect has not yet been explained.

OBJECTIVES

The aim of this study was to explore the mechanism by which PRF promotes fat graft survival, from the aspects of angiogenesis, adipogenesis, cellular apoptosis, and collagen production.

METHODS

Nude mice were randomly assigned to a PRF group (subcutaneously injected with PRF and fat in the ratio of 1:5 by volume) and a control group (subcutaneously injected with normal saline and fat in the ratio of 1:5 by volume). On days 0, 3, 7, 14, 21, and 28 after transplantation, graft samples (n = 12) were obtained for quantification of target growth factors. In weeks 1, 2, 3, and 4 after transplantation, graft samples (n = 12) were obtained for the following evaluations. The volume and weight retention rates were calculated; gene and protein expression of vascular endothelial growth factor A (VEGF-A), peroxisome proliferator-activated receptor γ (PPAR-γ), COL1-A1, and BAX were evaluated; hematoxylin & eosin staining, Masson's trichrome staining, α smooth muscle actin staining, and perilipin-1 staining were performed to evaluate graft survival.

RESULTS

After transplantation, the concentrations of growth factors produced by the fat increased to varying degrees, and the addition of PRF made these concentration changes ever greater. Compared with the control group, the PRF group had a higher volume and weight retention rate, a higher expression level of VEGF-A and PPAR-γ, a lower expression level of COL1-A1 and BAX, a higher vessel density, less fibrosis, and more viable adipocytes.

CONCLUSIONS

PRF can promote autocrine function of the grafted fat to produce more growth factors. It greatly increased fat retention rate, possibly by promoting vascularization and adipogenic differentiation, inhibiting cellular apoptosis, and regulating collagen production.

Surgical and Immunohistochemical Outcomes of Scleral Reconstruction with Autogenic, Allogenic and Xenogenic Grafts: An Experimental Rabbit Model

Purpose: Choukroun's platelet-rich fibrin (PRF), a second-generation platelet concentrate, has unique morphological and chemical features and may be considered as a scaffold for scleral reinforcement and regeneration. The purpose of this study was to compare the use of xenogenic human-derived amniotic membrane (HAM), allogenic sclera, and autogenic PRF in rabbit lamellar scleral defect model with respect to both anatomical and immunohistochemical improvement. Methods: A total of 45 adult New Zealand rabbits were randomized into five groups: normal control; without surgical procedure, negative control; scleral defect model (SDM), xenogenic HAM; SDM+HAM graft, allogenic sclera; SDM+allogenic sclera graft, autogenic PRF; SDM+autogenic PRF graft. Clinical findings, Hematoxylin&Eozin (HE), Masson Trichrome, Verhoeff Acid Fuchsin, Transforming Growth Factor β Receptor 1, Fibroblast Growth Factor, Bone Morphogenetic Protein 2, collagen type 1, aggrecan, and Matrix Metalloproteinase 2 were evaluated. Results: Ocular surface inflammation was significantly lower in normal control and autogenic PRF groups (p < .001). Graft was avascular and not integrated to scleral wound area in 25% rabbits of allogenic sclera group (p = .02), was out of the scleral wound in 33.3% rabbits of xenogenic HAM group (p > .05), all the grafts were at the normal location and viable in autogenic PRF group. The inflammation and vascularization in autogenic PRF group was significantly lower than negative control and xenogenic HAM groups in HE (p < .001). The collagen score of negative control and xenogenic HAM groups were significantly lower than normal control (p < .001) and autogenic PRF (p < .001) groups. There were insignificant differences between allogenic sclera and autogenic PRF groups (p > .05). For immunohistochemistry, the closest values to normal control group were detected in autogenic PRF group for all immunomarkers. Conclusion: Autogenic PRF showed superior features via its excellent anatomical and chemical composition for scleral regeneration when compared to single-layered xenogenic HAM and allogenic sclera grafts.

Autologous platelet concentrates in maxillofacial regenerative therapy

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

Involvement of PDGF-BB and IGF-1 in Activation of Human Schwann Cells by Platelet-Rich Plasma

BACKGROUND

Platelet-rich plasma contains high concentrations of growth factors that stimulate proliferation and migration of various cell types. Earlier experiments demonstrated that local platelet-rich plasma administration activates Schwann cells to improve axonal regeneration at a transected peripheral nerve lesion. However, the optimal concentration of human platelet-rich plasma for activation of human Schwann cells has not been determined, and mechanisms by which platelet-rich plasma activates Schwann cells remain to be clarified.

METHODS

Human Schwann cells were cultured with various concentrations of platelet-rich plasma in 5% fetal bovine serum/Dulbecco's Modified Eagle Medium. Cell viability, microchemotaxis, flow cytometry, and quantitative real-time polymerase chain reaction assays were performed to assess proliferation, migration, cell cycle, and neurotrophic factor expression of the human Schwann cells, respectively. Human Schwann cells were co-cultured with neuronal cells to assess their capacity to induce neurite extension. Neutralizing antibodies for platelet-derived growth factor-BB (PDGF-BB) and insulin-like growth factor-1 (IGF-1) were added to the culture to estimate contribution of these cytokines to human Schwann cell stimulation by platelet-rich plasma.

RESULTS

An addition of platelet-rich plasma at 5% strongly elevated proliferation, migration, and neurotrophic factor production of human Schwann cells. Both PDGF-BB and IGF-1 may be involved in mitogenic effect of platelet-rich plasma on human Schwann cells, and PDGF-BB may also play an important role in the migration-inducing effect of platelet-rich plasma. Neutralization of both PDGF-BB and IGF-1 cancelled the promoting effect of platelet-rich plasma on neurite-inducing activity of human Schwann cells.

CONCLUSION

This study may suggest the optimal concentration of platelet-rich plasma for human Schwann cell stimulation and potential mechanisms underlying the activation of human Schwann cells by platelet-rich plasma, which may be quite useful for platelet-rich plasma therapy for peripheral nerve regeneration.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

An Overview of Principles and New Techniques for Facial Fat Grafting

Facial fat grafting is a small-volume procedure and is primarily performed for facial rejuvenation, contouring, or regenerative surgery. The unsatisfying retention rate after fat grafting, however, led to unpredictable outcomes, subsequent multiple procedures, and even some complications. A variety of methods have been proposed to enhance the results of facial fat grafting, including several established surgical principles and many possible new techniques. Adding stem cells, fat preparations, and platelet concentrates may improve the survival after fat grafting but randomized controlled clinical studies are needed to determine their safety and efficacy as well as clinical indications for each technique.

Striking Differences in Platelet Distribution between Advanced-Platelet-Rich Fibrin and Concentrated Growth Factors: Effects of Silica-Containing Plastic Tubes

Compared with platelet-rich plasma, the preparation of platelet-rich fibrin (PRF) is simple and has not been overly modified. However, it was recently demonstrated that centrifugation conditions influence the composition of PRF and that silica microparticles from silica-coated plastic tubes can enter the PRF matrix. These factors may also modify platelet distribution. To examine these possibilities, we prepared PRF matrices using various types of blood-collection tubes (plain glass tubes and silica-containing plastic tubes) and different centrifugation speeds. The protocols of concentrated growth factors and advanced-PRF represented high- and low-speed centrifugation, respectively. Platelet distribution in the PRF matrix was examined immunohistochemically. Using low-speed centrifugation, platelets were distributed homogeneously within the PRF matrix regardless of tube types. In high-speed centrifugation, platelets were distributed mainly on one surface region of the PRF matrix in glass tubes, whereas in silica-coated tubes, platelet distribution was commonly more diffusive than in glass tubes. Therefore, both blood-collection tube types and centrifugal conditions appeared to influence platelet distribution in the PRF matrix. Platelets distributed in the deep regions of the PRF matrix may contribute to better growth factor retention and release. However, clinicians should be careful in using silica-coated tubes because their silica microparticles may be a health hazard.

Evidence for Contamination of Silica Microparticles in Advanced Platelet-Rich Fibrin Matrices Prepared Using Silica-Coated Plastic Tubes

Platelet-rich fibrin (PRF) therapy has been widely applied in regenerative dentistry, and PRF preparation has been optimized to efficiently form fibrin clots using plain glass tubes. Currently, a shortage of commercially available glass tubes has forced PRF users to utilize silica-coated plastic tubes. However, most plastic tubes are approved by regulatory authorities only for diagnostic use and remain to be approved for PRF therapy. To clarify this issue, we quantified silica microparticles incorporated into the PRF matrix. Blood samples were collected into three different brands of silica-containing plastic tubes and were immediately centrifuged following the protocol for advanced-PRF (A-PRF). Advanced-PRF-like matrices were examined using a scanning electron microscope (SEM), and silica microparticles were quantified using a spectrophotometer. Each brand used silica microparticles of specific size and appearance. Regardless of tube brands and individual donors, significant, but not accidental, levels of silica microparticles were found to be incorporated into the A-PRF-like matrix, which will be consequently incorporated into the implantation sites. Presently, from the increasing data for cytotoxicity of amorphous silica, we cannot exclude the possibility that such A-PRF-like matrices negatively influence tissue regeneration through induction of inflammation. Further investigation should be performed to clarify such potential risks.

Platelet-rich plasma (PRP) versus fibrin glue in cryptogenic fistula-in-ano: a phase III single-center, randomized, double-blind trial

PURPOSE

To compare the clinical outcome of autologous platelet-rich growth factor (PRP) with commercial fibrin glue in the management of high cryptogenic fistulae-in-ano.

METHOD

The study was conducted at a single center between July 2012 and July 2015 and performed as a phase III, randomized, double-blind comparison of autologously prepared PRP versus fibrin glue for cryptoglandular anal fistulae without active sepsis. Patients were assessed with clinical and endosonographic follow-up. Patients were followed up at 1 week and then at 3, 6, and 12 postoperative months. The primary outcome measure was the fistula healing rate (complete, partial, and non-healing) with secondary outcome measures assessing fistula recurrence, continence status, quality of life, and visual analog pain scores.

RESULTS

Of the 56 enrolled patients, 32 were PRP-treated and 24 were fibrin-treated. The groups were well matched for fistula type with an improved overall healing rate for PRP-treated over fibrin-treated cases (71% vs. 58.3%, respectively; P = 0.608); a complete healing rate of 48.4% vs. 41.7%, respectively; and a partial healing rate of 22.6% vs. 16.7%, respectively. The median pain scores of PRP-treated patients were lower at the first visit with a greater initial pain decrease early during follow-up. Improvements in pain reduction impacted the quality of life measures (P = 0.035). All adverse events were minor and no patient experienced a negative impact on continence.

CONCLUSION

Treatment of complex cryptoglandular anal fistula with autologous PRP is as effective as fibrin glue with less cost and no adverse effect on continence.

The Application of Three-Dimensional Printing Model and Platelet-Rich Fibrin Technology in Guided Tissue Regeneration Surgery for Severe Bone Defects

A 36-year-old male patient diagnosed with severe chronic periodontitis was treated with novel surgery for his maxillary right lateral incisor. Preoperatively, a 3D printer was used, based on CBCT datasets, to produce a photosensitive resin bony anatomy replica. The patient's blood was centrifuged to obtain advanced platelet-rich fibrin (A-PRF) and injected platelet-rich fibrin (I-PRF), then mixed with Bio-Oss and packed onto the 3D replica to form the ideal shape. The replica was positioned at the planned sites without changes. The A-PRF membrane was applied over the replica as well as a Bio-Gide collagen membrane. Fifteen months after the surgery, clinical and radiographic followup revealed greatly reduced pocket depths and significant 3D alveolar bone fill at the treatment site. Based on these short-term results, the initial 3D printing surgical temple assisted guided tissue regeneration method resulted in significant clinical and radiographic improvements; A-PRF/I-PRF should be considered an ideal biomaterial for regenerative periodontal therapy.

The use of fat grafting and platelet-rich plasma for wound healing: A review of the current evidence

Fat grafting is becoming a common procedure in regenerative medicine because of its high content of growth factors and adipose derived stem cells (ADSCs) and the ease of harvest, safety, and low cost. The high concentration of ADSCs found in fat has the potential to differentiate into a wide range of wound-healing cells including fibroblasts and keratinocytes as well as demonstrating proangiogenic qualities. This suggests that fat could play an important role in wound healing. However retention rates of fat grafts are highly variable due in part to inconsistent vascularisation of the transplanted fat. Furthermore, conditions such as diabetes, which have a high prevalence of chronic wounds, reduce the potency and regenerative potential of ADSCs. Platelet-rich plasma (PRP) is an autologous blood product rich in growth factors, cell adhesion molecules, and cytokines. It has been hypothesised that PRP may have a positive effect on the survival and retention of fat grafts because of improved proliferation and differentiations of ADSCs, reduced inflammation, and improved vascularisation. There is also increasing interest in a possible synergistic effect that PRP may have on the healing potential of fat, although the evidence for this is very limited. In this review, we evaluate the evidence in both in vitro and animal studies on the mechanistic relationship between fat and PRP and how this translates to a benefit in wound healing. We also discuss future directions for both research and clinical practice on how to enhance the regenerative potential of the combination of PRP and fat.