Leukocyte- and Platelet-Rich Fibrin (L-PRF) for Long-Term Delivery of Growth Factor in Rotator Cuff Repair: Review, Preliminary Results and Future Directions

Clinical Effect of Platelet-Rich Fibrin Combined with BIO-GENE Artificial Bone Meal in Bone Defects After Jaw Cyst Surgery

Purpose

To compare the clinical repair effects of leaving the defect empty and using Platelet-Rich Fibrin (PRF) combined with BIO-GENE artificial bone powder in patients with bone defects 6 months after jaw cystectomy.

Patients and Methods

From June 2021 to June 2022, 70 patients who were admitted to the Department of Stomatology, Affiliated Hospital of Yanbian University, and were diagnosed with jaw cysts postoperatively were selected. All of the patients were divided into two groups according to random method, among which 35 patients who underwent cystectomy alone were recorded as group A, which served as blank control; 35 patients who underwent cystectomy and PRF combined with BIO-GENE artificial bone meal repaired bone defects during the same period were recorded as group B. 3D Slicer 5.0.3 software was used to reconstruct Cone Beam Computed Tomography (CBCT) after operation. In this study, the preoperative and postoperative CBCT data of the patients were analyzed using 3D Slicer 5.0.3 software in DICOM format to calculate the cleft volume before surgery and the newly formed bone volume after surgery. The osteogenesis rate was measured based on these calculations.The bone formation percentage in the bone defect area was recorded at 6 months, and the clinical curative effects of the two groups were compared.

Results

After 6 months of surgery, the patients showed varying degrees of restoration in the jaw cyst area.The osteogenesis rate at 6 months in group A was 76.06±13.38%, while group B had a rate of 92.87±5.72%.The CBCT values in group B were higher than those in group A at 6 months post-surgery (P<0.05), t=-6.84.Group A and Group B showed a statistically significant difference.

Conclusion

Compared with simple cystectomy, PRF combined with BIO-GENE artificial bone powder has a better effect on the speed of bone repair after cystectomy within 6 months and provides more favorable effects for the repair of postoperative dentition defects, and provides support to repair teeth after defects such as dental implants.

The Effect of Leukocyte- and Platelet-Rich Fibrin on Central and Peripheral Nervous System Neurons-Implications for Biomaterial Applicability

Leukocyte- and Platelet-Rich Fibrin (L-PRF) is a second-generation platelet concentrate that is prepared directly from the patient's own blood. It is widely used in the field of regenerative medicine, and to better understand its clinical applicability we aimed to further explore the biological properties and effects of L-PRF on cells from the central and peripheral nervous system. To this end, L-PRF was prepared from healthy human donors, and confocal, transmission, and scanning electron microscopy as well as secretome analysis were performed on these clots. In addition, functional assays were completed to determine the effect of L-PRF on neural stem cells (NSCs), primary cortical neurons (pCNs), and peripheral dorsal root ganglion (DRG) neurons. We observed that L-PRF consists of a dense but porous fibrin network, containing leukocytes and aggregates of activated platelets that are distributed throughout the clot. Antibody array and ELISA confirmed that it is a reservoir for a plethora of growth factors. Key molecules that are known to have an effect on neuronal cell functions such as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) were slowly released over time from the clots. Next, we found that the L-PRF secretome had no significant effect on the proliferative and metabolic activity of NSCs, but it did act as a chemoattractant and improved the migration of these CNS-derived stem cells. More importantly, L-PRF growth factors had a detrimental effect on the survival of pCNs, and consequently, also interfered with their neurite outgrowth. In contrast, we found a positive effect on peripheral DRG neurons, and L-PRF growth factors improved their survival and significantly stimulated the outgrowth and branching of their neurites. Taken together, our study demonstrates the positive effects of the L-PRF secretome on peripheral neurons and supports its use in regenerative medicine but care should be taken when using it for CNS applications.

Effect of platelet concentrates for pain and symptom management in oral lichen planus: an evidence-based systematic review

BACKGROUND

Platelet Concentrate (PC) injection therapy has shown potential as a local therapy for oral lichen planus (OLP). However, its safety and efficacy have not yet been fully established. Our research compared the efficacy of PC with topical steroid treatment in alleviating pain and symptoms related to OLP. We aims to present evidence-based alternatives that dentists can use to improve patient outcomes while reducing potential side effects.

METHODS

We conducted a systematic search of five electronic databases up to April 2023, including Embase, Cochrane Central Register of Controlled Trials, PubMed, OVID Medline, and WanFang, to evaluate PCs' efficacy compared to topical corticosteroid therapy for OLP. The literature quality was assessed using the Cochrane ROB tool. A fixed-effects model was used to determine the Weighted Mean Difference (WMD) and Mean Difference (MD) at a 95% confidence interval (CI) for pain severity and other relevant clinical indicators.

RESULTS

The comparison between topical corticosteroid therapy and PCs showed no significant difference for pain relief (WMD = -0.07, CI = 95% -0.34 to 0.19), symptom improvement (MD = -0.21, CI = 95% -0.55 to 0.13), or the severity of included lesions measured by REU scores (MD = -0.25, CI = 95% -0.32 to 0.82).

CONCLUSIONS

Locally injected PC have been found efficient in managing oral lichen planus, indicating that they are a promising alternative option to steroid therapy for OLP patients, particularly those who have not responded favorably to steroid therapy. However, further research is needed to establish determining the recurrence rate and long-term adverse effects.

TRIAL REGISTRATION

The systematic review protocol has been registered in advance with the PROSPERO database (CRD42023415372).

Angiogenesis and Tissue Repair Depend on Platelet Dosing and Bioformulation Strategies Following Orthobiological Platelet-Rich Plasma Procedures: A Narrative Review

Angiogenesis is the formation of new blood vessel from existing vessels and is a critical first step in tissue repair following chronic disturbances in healing and degenerative tissues. Chronic pathoanatomic tissues are characterized by a high number of inflammatory cells; an overexpression of inflammatory mediators; such as tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1); the presence of mast cells, T cells, reactive oxygen species, and matrix metalloproteinases; and a decreased angiogenic capacity. Multiple studies have demonstrated that autologous orthobiological cellular preparations (e.g., platelet-rich plasma (PRP)) improve tissue repair and regenerate tissues. There are many PRP devices on the market. Unfortunately, they differ greatly in platelet numbers, cellular composition, and bioformulation. PRP is a platelet concentrate consisting of a high concentration of platelets, with or without certain leukocytes, platelet-derived growth factors (PGFs), cytokines, molecules, and signaling cells. Several PRP products have immunomodulatory capacities that can influence resident cells in a diseased microenvironment, inducing tissue repair or regeneration. Generally, PRP is a blood-derived product, regardless of its platelet number and bioformulation, and the literature indicates both positive and negative patient treatment outcomes. Strangely, the literature does not designate specific PRP preparation qualifications that can potentially contribute to tissue repair. Moreover, the literature scarcely addresses the impact of platelets and leukocytes in PRP on (neo)angiogenesis, other than a general one-size-fits-all statement that "PRP has angiogenic capabilities". Here, we review the cellular composition of all PRP constituents, including leukocytes, and describe the importance of platelet dosing and bioformulation strategies in orthobiological applications to initiate angiogenic pathways that re-establish microvasculature networks, facilitating the supply of oxygen and nutrients to impaired tissues.

Infiltration therapy in the context of cartilage surgery

Guideline-based surgical cartilage therapy for focal cartilage damage offers highly effective possibilities to sustainably reduce patients' complaints and to prevent or at least delay the development of early osteoarthritis. In the knee joint, it has the potential to reduce almost a quarter of the arthroses requiring joint replacement caused by cartilage damage. Biologically effective injection therapies could further improve these results. Based on the currently available literature and preclinical studies, intra- and postoperative injectables may have a positive effect of platelet-rich plasma/fibrin (PRP/PRF) and hyaluronic acid (HA) on cartilage regeneration and, in the case of HA injections, also on the clinical outcome can be assumed. The role of a combination therapy with use of intra-articular corticosteroids is lacking in the absence of adequate study data and cannot be defined yet. With regard to adipose tissue-based cell therapy, the current scientific data do not yet justify any recommendation for its use. Further studies also regarding application intervals, timing and differences in different joints are required.

Use of Leukocyte-rich and Platelet-rich Fibrin (L-PRF) Adjunct to Surgical Debridement in the Treatment of Stage 2 and 3 Medication-Related Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) is characterized by exposed necrotic bone persisting for more than 8 weeks in the maxillofacial region in patients using antiresorptive or antiangiogenetic drugs for several treatment options like bone metastasis or osteoporosis. There are several treatment options studied in scientific literature, and one of them with promising results is using platelet concentrates adjunct to surgical therapy. The aim of this study is to examine the therapeutic effect of leukocyte and platelet-rich fibrin (L-PRF) on patients with MRONJ. This 2-centered study investigated patients referred to oral and maxillofacial surgery departments of 2 university clinics between the years 2014 and 2020 with the diagnosis of MRONJ. Demographic data, the indication of the drug usage, drug type, duration, administration route, and systemic comorbidities of the patients were recorded. L-PRF was applied to 20 osteonecrotic lesions of 19 patients following surgical debridement. The male/female ratio was 5/14. Except 1 of the patients, all of the indications of medication were neoplasia-related. The mean follow-up period of patients was 27.9±9.2 months. Most common antirezorptive drug was zoledronate (84.2%). Complete resolution was observed in 16 necrosis sites (80%). It could be concluded that the use of L-PRF may represent an important adjunct in the surgical management of MRONJ.

Comparative analysis of the effect of 4MATRIX with and without PRF on regeneration of infrabony periodontal pockets

Aim

The aim was to compare the effect in improvement of periodontal pocket depth (PPD) and clinical attachment level (CAL) between application of 4MATRIX and 4 MATRIX combined with PRF in advanced periodontal disease during follow-up of 6, 12 and 18 months.

Methods

Thirty patients of both genders aged 25-50 years were included. The patients were clinically and radiologically diagnosed with generalized advanced chronic periodontitis with the presence of periodontal pockets with a depth of ≥ 5 mm bilaterally in the upper jaw. Both sides were treated with a flap intervention in all patients. On one side a bone substitute 4MATRIX was applied, and the other side was treated with an application 4MATRIX and PRF. The clinical assessment and measurements were performed in four stages, immediately before the intervention, and then 6, 12 and 18 months after the intervention. PPD and CAL were determined in all four timepoints.

Results

PPD was the highest at zero time before the surgery for both groups and was 5.56 ± 0.28 mm. In the postoperative follow-up period, the PPD value decreased gradually with the lowest average value of 5.10 ± 0.18 mm after 18 months in Group I and 4.67 ± 0.13 mm in Group II (p < 0.001, respectively). Moreover, comparing the values of PPD at 6, 12 and 18 months after the surgery, a significant difference was found between the patients from the 4MATRIX vs 4MATRIX + PRF (p < 0.001 respectively). The postoperative follow-up period showed a decrease in CAL value with the lowest value after 18 months. A significant difference in CAL was found between the four measurement times (p < 0.001, respectively). The average level of CAL was the highest before surgical treatment in both groups. The intergroup analysis of CAL after 18 months in group I (4MATRIX) was 5.27 ± 0.17 mm and in group II 4.10 ± 0.14 mm (p < 0.001).

Conclusion

Treatment of adult patients with advanced chronic periodontitis with periodontal pockets of ≥ 5 mm bilaterally in the upper jaw using 4MATRIX and 4MATRIX + PRF showed improvement of PPD and lower CAL loss after 18 months of the treatment. In the group treated with 4MATRIX + PRF patients showed the highest improvement in PPD and CAL loss. The analysis of treatment with 4MATRIX and 4MATRIX + PRF showed the lowest values after 18 months of the treatment.

Pure Platelet and Leukocyte-Platelet-Rich Plasma for Regenerative Medicine in Orthopedics-Time- and Preparation-Dependent Release of Growth Factors and Effects on Synovial Fibroblasts: A Comparative Analysis

Intra-articular injections of autologous platelet concentrates are considered capable to enhance the healing of cartilage lesions, alleviate joint inflammation, and relieve other musculoskeletal pathological conditions. The aim of this study was to analyze the soluble fractions obtained from platelet-rich plasma (pure- and leukocyte-PRP) to compare time- and preparation-dependent modifications of growth factor concentrations and the supporting activity of the two preparations on synovial fibroblast growth and hyaluronic acid (HA) production in vitro. The release kinetics of FGF-2, SDF-1, VEGF, HGF, EGF, PD GF-AB/BB, IGF-1, VCAM-1, and TGF-β isoforms were followed up to 168 h after PRP activation, and their amounts were determined by multiplex-beads immunoassay. Synovial cell growth and supernatant HA production were respectively analyzed by Alamar Blue assay and ELISA. Time-dependent modifications grouped molecules in three peculiar patterns: one reaching the highest concentrations within 18 h and decreasing afterwards, another progressively increasing up to 168 h, and the last peaking at the central time points. Synovial fibroblast growth in response to L-PRP and P-PRP revealed differences over time and among added concentrations. Both preparations displayed a preserved supporting capacity of HA synthesis.

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.

Advanced Biomaterials, Coatings, and Techniques: Applications in Medicine and Dentistry

The field of biomaterials is very extensive, encompassing both the materials themselves and the manufacturing methods, which are constantly developing [...]

Novel Growth Factor Combination for Improving Rotator Cuff Repair: A Rat In Vivo Study

BACKGROUND

The lack of healing at the repaired tendon-bone interface is an important cause of failure after rotator cuff repair. While augmentation with growth factors (GFs) has demonstrated promise, the ideal combination must target all 3 tissue types at the tendon-bone interface.

HYPOTHESIS

The GF combination of transforming growth factor beta 1, Insulin-like growth factor 1, and parathyroid hormone will promote tenocyte proliferation and differentiation and improve the biomechanical and histological quality of the repaired tendon-bone interface.

STUDY DESIGN

Controlled laboratory study.

METHODS

In vitro, human tenocytes were cultured in the presence of the GF combination for 72 hours, and cell growth assays and the expression of genes specific to tendon, cartilage, and bone were analyzed. In vivo, adult rats (N = 46) underwent detachment and repair of the left supraspinatus tendon. A PVA-tyramine gel was used to deliver the GF combination to the tendon-bone interface. Histological, biomechanical, and RNA microarray analysis was performed at 6 and 12 weeks after surgery. Immunohistochemistry for type II and X collagen was performed at 12 weeks.

RESULTS

When treated with the GF combination in vitro, human tenocytes proliferated 1.5 times more than control (P = .04). The expression of scleraxis increased 65-fold (P = .013). The expression of Sox-9 (P = .011), type I collagen (P = .021), fibromodulin (P = .0075), and biglycan (P = .010) was also significantly increased, while the expression of PPARγ was decreased (P = .007). At 6 and 12 weeks postoperatively, the quality of healing on histology was significantly higher in the GF group, with the formation of a more mature tendon-bone interface, as confirmed by immunohistochemistry for type II and X collagen. The GF group achieved a load at failure and Young modulus >1.5 times higher at both time points. Microarrays at 6 weeks demonstrated upregulation of genes involved in leukocyte aggregation (S100A8, S100A9) and tissue mineralization (Bglap, serglycin, Fam20c).

CONCLUSION

The GF combination promoted protendon and cartilage responses in human tenocytes in vitro; it also improved the histological appearance and mechanical properties of the repair in vivo. Microarrays of the tendon-bone interface identified inflammatory and mineralization pathways affected by the GF combination, providing novel therapeutic targets for further research.

CLINICAL RELEVANCE

The use of this GF combination is translatable to patients and may improve healing after rotator cuff repair.

Feasibility of Growth Factor Agent Therapy in Repairing Motor Injury

Growth factors (GF), with the activity of stimulating cell growth, play a significant role in biology, medicine, and exercise physiology. In the process of exercise, human tissues are impacted, making cells suffer damage. Growth factor can accelerate the repair of damaged cells and regulate the synthesis of protein, so biological preparations of growth factors can be added to traditional therapies. A combination of growth factor biologics and conventional therapies may improve the efficiency of injury repair, but growth factor biologics may not produce any results. The feasibility of growth factor biologics in the treatment of motor injury was discussed. The research have shown that: 1) GF biological agent therapy is a very promising treatment for motor injury, which is based on the power of autologous growth factor (GFs) to accelerate tissue healing, promote muscle regeneration, increase angiogenesis, reduce fibrosis, and make the muscle injury rapid recovery. 2) There are various methods for delivering the higher dose of GF to the injured tissue, but most of them depend on the platelet release of GF. At the site of injury, there are several ways to deliver higher doses of GF to the injured tissue. 3) At present, the inhibition of GF is mainly through signal transduction inhibitors and inhibition of transcription factor production. 4) Pattern of GF during wound repair: GF directly regulates many key steps of normal wound repair, including inflammatory cell chemotaxis, division and proliferation of fibroblasts, keratinocytes and vascular endothelial cells, formation of new blood vessels, and synthesis and degradation of intercellular substances. 5) When GF promotes chronic wound healing, in most cases, certain GF can be used targeted only when in vivo regulation still cannot meet the need for repair.

Promising results of surgical management of advanced medication related osteonecrosis of the jaws using adjunctive leukocyte and platelet rich fibrin

Background

Leukocyte- and platelet-rich fibrin (L-PRF) is an autologous matrix scaffold which regulates inflammation by stimulating cytokines and growth factors that are involved in the immune response. L-PRF is suggested as a viable adjunctive method to surgical interventions due to its advantages on tissue healing. This study aims to retrospectively evaluate the adjunctive role of L-PRF in surgically treated medication-related osteonecrosis of the jaws (MRONJ) patients.

Methods

Between January 2012 and December 2020, patients with AAOMS stage II and III MRONJ lesions, who were treated surgically with adjunctive use of L-PRF in the authors’ institution were enrolled. Surgical interventions consisted of either marginal resection or sequestrectomy with peripheral ostectomy (SPO) or curettage and L-PRF application. Medical records of these patients were retrospectively reviewed and healing was assessed according to certain parameters including mucosal closure and presence of infection, exposed bone, fistula or radiologic markers of disease progression for a minimum of 12 months.

Results

Thirteen patients (7 women and 6 men) with an average age of 72.4 years (± 10.61, range 54–84) were included in the study, nine of whom had AAOMS stage III and four stage II MRONJ. Three patients had a marginal resection, nine patients had sequestrectomy with peripheral ostectomy (SPO) and one patient underwent a curettage procedure. All marginal resection and six SPO patients showed complete healing while four patients, who had SPO or curettage experienced incomplete healing. Mean follow up was 20.1 ± 18.29 months.

Conclusion

The use of L-PRF may be a favorable adjunctive option in the treatment of MRONJ owing to its favorable effects on tissue repair, ease of application, minimally invasive and cost-effective character and autogenous nature.

Trial registration Retrospectively registered.

Apheresis Platelet Rich-Plasma for Regenerative Medicine: An In Vitro Study on Osteogenic Potential

Background: Platelet-Rich Plasma (PRP) induces bone regeneration; however, there is low evidence supporting its efficacy in bone healing. The lack of a standardized protocol of administration represents the main obstacle to its use in the clinical routine for bone defects’ treatment. The purpose of this study was to characterize PRP and elucidate its osteogenic potential. Methods: Platelet count, fibrinogen levels, and growth factors concentration were measured in PRP obtained by four apheresis procedures. HOB-01-C1, a pre-osteocytic cell line, was used to examine the effects of different PRP dilutions (from 1% to 50%) on cell viability, growth, and differentiation. Gene expression of RUNX2, PHEX, COL1A1, and OCN was also assayed. Results: PRP showed a mean 4.6-fold increase of platelets amount compared to whole blood. Among the 36 proteins evaluated, we found the highest concentrations for PDGF isoforms, EGF, TGF-β and VEGF-D. PDGF-AA positively correlated with platelet counts. In three of the four tested units, 25% PRP induced a growth rate comparable to the positive control (10% FBS); whereas, for all the tested units, 10% PRP treatment sustained differentiation. Conclusions: This study showed that PRP from apheresis stimulates proliferation and differentiation of pre-osteocyte cells through the release of growth factors from platelets.

Platelet-Rich Product Supplementation in Rotator Cuff Repair Reduces Retear Rates and Improves Clinical Outcomes: A Meta-analysis of Randomized Controlled Trials

PURPOSE

The purpose of this study was to conduct a comprehensive systematic review and meta-analysis to investigate the clinical and imaging outcomes of all 4 types of platelet-rich therapies (pure platelet-rich plasma [P-PRP], leukocyte and platelet-rich plasma, pure platelet-rich fibrin, and leukocyte and platelet-rich fibrin) in rotator cuff repairs.

METHODS

A systematic literature search was performed to identify rotator cuff tears comparing any of the 4 types of platelet-rich products (PRP) to a control in rotator cuff repair. Data extracted from the studies included retear rates diagnosed with imaging studies, as well as outcome scores such as Constant, American Shoulder and Elbow Surgeons (ASES), University of California Los Angeles (UCLA), Simple Shoulder Test (SST), and visual analog scale (VAS). Meta-analyses compared postoperative outcome scores and retear rates between the control and study groups.

RESULTS

Seventeen studies were included in the meta-analysis. When pooling data from all studies, retear rate for the treatment group was 19.3%, compared to 25.4% for the control group (odds ratio [OR] 0.59, P = .0037). When stratified based on PRP type, only P-PRP resulted in a significant reduction in retear rate (OR 0.26, P = .0005). Overall, treatment with PRP significantly improved Constant scores when compared to controls (mean difference [MD] 2.41, P =.0027), as well as VAS scores (MD -0.12, P = .0014), and SST scores (MD 0.41, P = .0126). There was no significant difference in ASES scores (MD 0.37, P = .7762) or UCLA scores (MD 0.76, P =0.2447) between treatment and controls when pooling data from all studies.

CONCLUSIONS

This analysis demonstrates significant reductions in retear rates when rotator cuff repair is augmented with PRP. P-PRP appears to be the most effective formulation, resulting in significantly improved retear rates and clinical outcome scores when compared with controls.

Randomized and Controlled Clinical Trial of Bone Healing After Alveolar Ridge Preservation Using Xenografts and Allografts Versus Plasma Rich in Growth Factors

The aim of this study was to compare bone regeneration in the anterior maxilla between bone substitutes and autologous platelet concentrate in alveolar ridge preservation. Forty patients requiring tooth extraction in the anterior maxilla were randomly allocated to the following 4 treatment modalities: spontaneous healing (control), natural bovine bone mineral covered with resorbable native collagen membrane (BBM/CM), freeze-dried bone allograft covered with resorbable native collagen membrane (FDBA/CM), and plasma rich in growth factors (PRGF) alone. Bone biopsies and histomorphometrical analysis were performed after 3 months of healing. The following parameters were assessed: newly formed mineralized tissue, newly formed nonmineralized tissue, and residual bone-grafting material (if applicable). Statistical analysis was performed to provide descriptive analysis and to compare the parameters of the bone regeneration between the study groups. Histomorphometrical analysis revealed the highest new mineralized tissue formation in the PRGF group. Statistically significant differences in new mineralized tissue formation were found between control/PRGF (46.4% ± 15.2% vs 75.5% ± 16.3%), control/(BBM/CM) (46.4% ± 15.2% vs 20.3% ± 21.9%), control/(FDBA/CM) (46.4% ± 15.2% vs 7.2% ± 8.6%), PRGF/(BBM/CM) (75.5% ± 16.3% vs 20.3% ± 21.9%), and PRGF/(FDBA/CM) (75.5% ± 16.3% vs 7.2% ± 8.6%) groups. The new mineralized tissue formation was in the following order: PRGF > control > BBM > FDBA. Alveolar ridge preservation in the esthetic zone with PRGF was the most effective for bone regeneration of the alveolar ridge.

Evidence-Based Clinical Efficacy of Leukocyte and Platelet-Rich Fibrin in Maxillary Sinus Floor Lift, Graft and Surgical Augmentation Procedures

Bone augmentation techniques have increasingly been indicated for re-creating adequate bone height and volume suitable for dental implant sites. This is particularly applicable in the severely atrophic posterior maxilla where sinus perforation (ruptured Schneiderian membrane) is a very common complication and sinus floor elevation or lift is frequently considered a standard procedure. The augmentation of the maxillary sinus can be performed with or without grafting biomaterials. Herein, numerous biomaterials and bone substitutes have been proposed, primarily to sustain the lifted space. In addition, cytokines and growth factors have been used to stimulate angiogenesis, enhance bone formation as well as improve healing and recovery period, either as the sole filling material or in combination with bone substitute materials. Within such, is the family of autologous blood extracts, so-called platelet concentrates, which are simply the "product" resulting from the simple centrifugation of collected whole blood samples of the patient, immediately pre-surgery. Platelet-Rich Fibrin (PRF), a sub-family of platelet concentrates, is a three-dimensional (3-D) autogenous biomaterial obtained, without including anti-coagulants, bovine thrombin, additives, or any gelifying agents during the centrifugation process. Today, it is safe to say that, in implant dentistry and oral and maxillofacial surgery, PRFs (particularly, the pure platelet-rich fibrin or P-PRF and leukocyte and platelet-rich fibrin or L-PRF sub-classes) are receiving the most attention, essentially due to their simplicity, rapidness, user-friendliness/malleability, and cost-effectiveness. Whether used as the sole "bioactive" filling/additive material or combined with bone substitutes, the revolutionary second-generation PRFs have been very often associated with promising clinical results. Hence, this review aims to provide a 10-years update on the clinical effectiveness of L-PRF when applied/used as the "sole" biomaterial in maxillary sinus augmentation procedures. An electronic search using specific keywords for L-PRF and maxillary sinus augmentation was conducted in three main databases (PubMed-MEDLINE database, Google Scholar and Cochrane library) for the period between January 2009-February 2020. The quest yielded a total of 468 articles. Based on the pre-established strict inclusion/exclusion criteria, only seven articles were deemed eligible and included in the analysis. Surprisingly, of the 5 studies which used de-proteinized bovine bone mineral (DBBM) in combination with L-PRF, 60% acclaimed no significant effects and only 40% declared positive effects. Of the two articles which had used allogenous bone graft, 50% declared no significant effects and 50% acclaimed positive effects. Only one study had used L-PRF as the sole grafting material and reported a positive effect. Likewise, positive effects were reported in one other study using L-PRF in combination with a collagen membrane. Due to the heterogeneity of the included studies, this review is limited by the inability to perform a proper systematic meta-analysis. Overall, most of the published studies reported impressive results of L-PRF application as a grafting material (sole or adjuvant) in maxillary sinus augmentation and dental implant restorative procedures. Yet, distinct technical processing for L-PRF preparation was noted. Hence, studies should be approached with caution. Here in, in sinus lift and treatment of Schneider membrane, the formation of mature bone remains inconclusive. More studies are eagerly awaited in order to prove the beneficial or detrimental effects of PRFs, in general and L-PRFs, in specific; especially in their tissue regenerative potential pertaining to the promotion of angiogenesis, enhancing of cell proliferation, stimulation of cell migration and autocrine/paracrine secretion of growth factors, as well as to reach a consensus or a conclusive and distinct determination of the effect of leukocytes (and their inclusion) on inflammation or edema and pain; a call for standardization in PRFs and L-PRFs composition reporting and regimenting the preparation protocols.

Effects of applying platelet-rich plasma during arthroscopic rotator cuff repair: a systematic review and meta-analysis of randomised controlled trials

Because of its healing properties, platelet-rich plasma (PRP) has been applied to the bone-tendon interface during arthroscopic rotator cuff repair to improve surgical outcomes. However, its effects remain ambiguous. Therefore, we conducted this systematic review and meta-analysis to assess the effects of PRP on retear rate and functional outcomes. Randomised control trials were identified and extracted. Data collection was completed on 15 February 2020. The results are expressed as the risk ratio (RR) for the categorical variables and weighted mean difference for the continuous variables, with 95% confidence intervals (CIs). Analyses were performed using RevMan 5.3 software. Seven randomised controlled trials published from 2013 to 2018, with 541 patients in total, were included. The results revealed a significant decrease in retear rate [RR 0.38, 95% CI (0.22, 0.68), P = 0.0009). Furthermore, a significant improvement was observed regarding short-term Constant score [mean difference = 3.28, 95% CI (1.46, 5.11), P = 0.0004), short-term University of California at Los Angeles activity score [mean difference = 1.60, 95% CI (0.79, 2.42), P = 0.0001], and short-term visual analogue scale score [mean difference =  - 0.14, 95% CI (- 0.23, - 0.05), P = 0.002]. This systematic review indicates the efficacy of PRP when applied to the bone-tendon interface during arthroscopic rotator cuff repair.

In vivo behavior of untreated and compressed concentrated growth factors as biomaterials in rabbits

To characterize concentrated growth factors (CGFs) in vivo, we examined the degradation of implanted CGF in rabbits. Untreated CGF (U-CGF) and compressed CGF (C-CGF) were subcutaneously implanted into the dorsum. Histological analyses showed that the U-CGF and C-CGF induced very few inflammatory cells and that the U-CGF and C-CGF were subsequently degraded with dendritic invasion of granulation tissue. The C-CGF histopathologically remained for longer term than the U-CGF. Aggregated CD31+ and RAM11+ cells appeared in and around the implanted CGF. The number of macrophages and blood vessels in the CGF-implanted groups was greater than that in the sham group. There were more blood vessels in the U-CGF group than that in the C-CGF and sham group. We showed that CGF was degraded by macrophages in 4 weeks and enhanced angiogenesis with dendritically branching new capillaries. Therefore, the U-CGF and C-CGF can be clinically applied as a biomaterial inducing angiogenesis.

Bone regeneration in rabbit calvarial defects using PRGF and adipose-derived stem cells: histomorphometrical analysis

Aim: The aim of this study was to evaluate the osteogenic potential of adipose-derived stem cells (ADSCs) and to assess the influence of plasma rich in growth factors (PRGF) on bone regeneration using ADSCs. Materials & methods: Bone defects were randomly allocated to the five treatment modalities: spontaneous healing, natural bovine bone mineral (BBM), BBM loaded with PRGF, BBM loaded with ADSCs and BBM loaded with a combination of ADSCs and PRGF. Results: The PRGF significantly enhanced the biomaterial-to-bone contact. Defects treated with ADSCs and PRGF or a combination of both showed the greatest bone regeneration. Conclusion: Combining PRGF and ADSCs boosts the bone graft regenerative potential at the earliest period of healing.

In vitro and in vivo effects of concentrated growth factor on cells and tissues

This article reviews the biological outcome of the concentrated growth factor (CGF), a new platelet derivative used for tissue regeneration, in published articles related to the use of this product in basic and clinical studies. An electronic literature research using PubMed and SCOPUS was performed using combination of keywords: "concentrated growth factor" (OR "CGF"), AND "stem cells," AND "cells" OR "cell proliferation" OR "cell migration" OR "cell differentiation," AND "repair" OR "survival" OR "revitalization," AND "tissue" OR "bone." Forty-five articles that were published between 2012 and 2020 met the inclusion criteria. These studies have used CGF as fresh solid form, freeze-dried, membrane, extract, or exudate. Most studies demonstrate the positive effects of CGF in a dose-dependent manner under certain concentrations. Studies comparing CGF with other platelet concentrates, report lower efficiency, no statistically significant differences, or better results for CGF. Combination of CGF with stem cells and biomaterials significantly improves bone regeneration and the effect of allograft or collagen membrane is better than CGF alone. For a better examination of the biological outcomes of CGF, the standardization of CGF preparation regarding the choice of the test tube material for blood collection, the required volume of blood, the necessary count of platelets in CGF, and the most appropriate type of CGF are recommended.

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 Fibrin and its Emerging Therapeutic Benefits for Musculoskeletal Injury Treatment

New therapies that accelerate musculoskeletal tissue recovery are highly desirable. Platelet-rich fibrin (PRF) is a leukocyte- and platelet-rich fibrin biomaterial that acts as a binding site for both platelets and growth factors. Through increasing the local concentration of growth factors at specific tissues, PRF promotes tissue regeneration. PRF has been frequently used in combination with bone graft materials to reduce healing times and promote bone regeneration during maxillofacial surgery. However, its benefits during muscle repair and recovery are less well-documented. Here, we perform a narrative review on PRF therapies and muscle injuries to ascertain its beneficial effects. We reviewed the factors that contribute to the biological activity of PRF and the published pre-clinical and clinical evidence to support its emerging use in musculoskeletal therapy. We include in vitro studies, in vivo animal studies and clinical articles highlighting both the success and failures of PRF treatment. PRF can promote the healing process when used in a range of orthopaedic and sports-related injuries. These include cartilage repair, rotator cuff surgery and anterior cruciate ligament surgery. However, conflicting data for these benefits have been reported, most likely due to inconsistencies in both PRF preparation protocols and dosing regimens. Despite this, the literature generally supports the use of PRF as a beneficial adjuvant for a range of chronic muscle, tendon, bone or other soft tissue injuries. Further clinical trials to confirm these benefits require consistency in PRF preparation and the classification of a successful clinical outcome to fully harness its potential.

Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside

Nowadays, research in Tissue Engineering and Regenerative Medicine is focusing on the identification of instructive scaffolds to address the requirements of both clinicians and patients to achieve prompt and adequate healing in case of injury. Among biomaterials, hemocomponents, and in particular Platelet-rich Fibrin matrices, have aroused widespread interest, acting as delivery platforms for growth factors, cytokines and immune/stem-like cells for immunomodulation; their autologous origin and ready availability are also noteworthy aspects, as safety- and cost-related factors and practical aspects make it possible to shorten surgical interventions. In fact, several authors have focused on the use of Platelet-rich Fibrin in cartilage and tendon tissue engineering, reporting an increasing number of in vitro, pre-clinical and clinical studies. This narrative review attempts to compare the relevant advances in the field, with particular reference being made to the regenerative role of platelet-derived growth factors, as well as the main pre-clinical and clinical research on Platelet-rich Fibrin in chondrogenesis and tenogenesis, thereby providing a basis for critical revision of the topic.

A Novel Method of Obtaining Platelet Rich Fibrin from Rats and Quantifying Platelet Count

Background and objectives: Rat experimentation is the first line of research by which a medical hypothesis is usually tested. Platelet Rich Fibrin (PRF) is a relatively new bio-material that has shown promise to enhance healing in the field of bone research and tissue engineering. In order to perform PRF based experiments on rats, a proper protocol of obtaining PRF from rats needs to be established. Materials and Methods: 35 Wistar rats were used to obtain PRF by using cardiac puncture blood draw and quick subsequent centrifugation. The PRF samples wereanalyzed and compared to standard literature PRF composition. Results: PRF samples analysis showed persistent results pertaining to known PRF composition. Conclusions: Our experiment has shown that our protocol of obtaining PRF is capable of providing high quality PRF from rats.

The Efficacy of Platelet-Rich Plasma and Platelet-Rich Fibrin in Arthroscopic Rotator Cuff Repair: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Basic science studies suggest that platelet-rich therapies have a positive effect on tendon repair. However, the clinical evidence is conflicted on whether this translates to increased tendon healing and improved functional outcomes.

PURPOSE

To perform a systematic review of randomized controlled trials (RCTs) in the literature to ascertain whether platelet-rich plasma (PRP) or platelet-rich fibrin (PRF) improved patient outcomes in arthroscopic rotator cuff repair.

STUDY DESIGN

Meta-analysis.

METHODS

Two independent reviewers performed the literature search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, with a third author resolving any discrepancies. RCTs comparing PRP or PRF to a control in rotator cuff repair were included. Quality of evidence was assessed using the Jadad score. Clinical outcomes were compared using the risk ratio for dichotomous variables and the mean difference for continuous variables. A P value <.05 was deemed statistically significant.

RESULTS

Eighteen RCTs with 1147 patients were included in this review. PRP resulted in significantly decreased rates of incomplete tendon healing for all tears combined (17.2% vs 30.5%, respectively; P < .05), incomplete tendon healing in small-medium tears (22.4% vs 38.3%, respectively; P < .05), and incomplete tendon healing in medium-large tears (12.3% vs 30.5%, respectively; P < .05) compared to the control. There was a significant result in favor of PRP for the Constant score (85.6 vs 83.1, respectively; P < .05) and the visual analog scale score for pain at 30 days postoperatively (2.9 vs 4.3, respectively; P < .05) and at final follow-up (1.2 vs 1.4, respectively; P < .05) compared to the control. PRF did not result in a significantly decreased rate of incomplete tendon healing for all tears combined (23.0% vs 24.6%, respectively; P = .74) or an improved Constant score (80.8 vs 79.8, respectively; P = .27) compared to the control. PRF resulted in a significantly longer operation time (99.1 vs 83.3 minutes, respectively; P< .05) compared to the control.

CONCLUSION

The current evidence indicates that the use of PRP in rotator cuff repair results in improved healing rates, pain levels, and functional outcomes. In contrast, PRF has been shown to have no benefit in improving tendon healing rates or functional outcomes.

Platelet derived growth factor-BB levels in gingival crevicular fluid of localized intrabony defect sites treated with platelet rich fibrin membrane or collagen membrane containing recombinant human platelet derived growth factor-BB: A randomized clinical and biochemical study

BACKGROUND

Development of autologous and recombinant growth factor/matrix combination products represent a new emerging trend in regenerative therapeutics and have gained increasing attention as a strategy to optimize tissue regeneration. The aim of the present study was to evaluate the levels of platelet derived growth factor-BB (PDGF-BB) in gingival crevicular fluid (GCF) during early healing period after the regenerative treatment of intrabony defects using beta tricalcium phosphate (β-TCP) as a bone regeneration material with either platelet rich fibrin (PRF) membrane or collagen membrane (CM) treated with recombinant human PDGF-BB (rhPDGF-BB).

METHODS

Twenty patients (13 males and 7 females) with chronic periodontitis participated in this prospective, randomized clinical and biochemical study. Each patient was randomly assigned to PRF membrane (group A) or CM incorporated with rhPDGF-BB (group B). GCF samples were obtained on days 3, 7, 14, and 30 for evaluation of PDGF-BB levels and alkaline phosphatase (ALP) levels.

RESULTS

On days 3 and 7 following surgery, mean levels of PDGF-BB at sites treated with PRF membrane or CM incorporated with rhPDGF-BB as a barrier membrane were not significantly different. PDGF-BB levels decreased significantly in samples collected on days 14 and 30 with significant differences between both the groups. ALP levels significantly increased from day 3 to day 30 but there was no difference between two groups.

CONCLUSION

Within the limitations of the study, both PRF membrane and CM incorporated with rhPDGF-BB showed comparable GCF levels of PDGF-BB initially with PRF showing more sustained levels throughout the study period.

Does Intraoperative Platelet-rich Plasma Improve Clinical and Structural Outcomes after Arthroscopic Repair of Isolated Tears of the Supraspinatus Tendon?

BACKGROUND

Arthroscopic cuff repair is a highly successful technique, but postoperative rehabilitation is complex and the rate of tear recurrence is not negligible. Biological augmentations have been proposed to overcome these drawbacks. The platelet-rich plasma (PRP) is a platelet-rich blood fraction that is applied on the repair site to enhance tendon healing. This study evaluates the effectiveness of PRP application in arthroscopic cuff repair.

MATERIALS AND METHODS

A prospective nonrandomized study was carried out on 22 patients undergoing arthroscopic rotator cuff repair. Only patients with isolated and repairable supraspinatus tears were included and divided into two groups: 11 patients (Group A) received intraoperative PRP and 11 patients (Group B) did not. All patients had the same rehabilitation and followup protocol. Clinical-functional parameters (visual analog score, active range of motion, University of California at Los Angeles - UCLA, Constant) were recorded at predefined intervals, and magnetic resonance imaging (MRI) was performed 1 year postoperative.

RESULTS

Only one patient of Group B did not complete the study protocol. No intraoperative or postoperative complications were observed. No differences were found in the clinical-functional parameters during the entire study. At 1 year, MRI showed 1 retear in Group A and 2 retears in Group B, but the difference was not significant.

CONCLUSIONS

The role of PRP as an adjuvant for surgical repair of rotator cuff tears is controversial. In this study, we could not demonstrate significant advantages of PRP for arthroscopic repair of isolated supraspinatus tears. The potential improvement in the structural outcome should be evaluated in the long term to justify the additional costs related to PRP application.

The effect of leukocyte-platelet-rich fibrin on bone morphogenetic protein-2 and insulin-like growth factor-1 levels in patients with chronic periodontitis: a randomized split mouth clinical trail

The present study evaluates the effects of leukocyte-platelet-rich fibrin (L-PRF) combined with open flap debridement (OFD) on clinical parameters and growth factors levels (GFL) in chronic periodontitis (CP) patients. This trial was registered at clinicaltrials.gov as NCT02594605. 16 patients (32 sites) with chronic periodontitis who had at least two areas of horizontal bone loss, were treated with OFD alone or L-PRF with OFD (OFD + L-PRF). GFL in gingival crevicular fluid (GCF) were analyzed at baseline, 1 week, 2 weeks and 4 weeks after operation. Probing depth (PD) and clinical attachment level (CAL) were measured at baseline and 6 months postoperatively. PD reduction and CAL gain were significantly higher in the OFD + L-PRF sites than in OFD sites. OFD + L-PRF group showed significantly increased bone morphogenetic protein-2 and insulin-like growth factor-1 at 2 weeks compared with baseline. L-PRF combined with OFD significantly increases GFL and thus, it enhances the periodontal healing on CP patients.

Clinical and Structural Evaluations of Rotator Cuff Repair With and Without Added Platelet-Rich Plasma at 5-Year Follow-up: A Prospective Randomized Study

BACKGROUND

Platelet-rich plasma (PRP) has been studied with the objective of reducing the retear rate and improving functional outcomes after rotator cuff repair. Only one study to date has reported its midterm effect.

HYPOTHESIS

PRP promotes better functional and structural results in arthroscopic rotator cuff repair.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

All patients underwent arthroscopic single-row repair of small to medium supraspinatus tears. At the end of the surgical procedure, liquid PRP prepared by apheresis with autologous thrombin was applied in the tendon-to-bone interface in the PRP group. The outcomes were assessed by the University of California, Los Angeles (UCLA) and Constant scales and the visual analog scale (VAS) for pain at 6, 12, 24, and 60 months after surgery and magnetic resonance imaging at 12 and 60 months.

RESULTS

Of 54 patients initially randomized, we analyzed the clinical outcomes in 51 (25 control, 26 PRP) and the structural outcomes in 44 (22 each group). At 60-month follow-up, the mean UCLA scores were 32.5 ± 3.8 and 32.1 ± 4.6 in the control and PRP groups, respectively ( P = .992). The mean Constant scores were 82.0 ± 9.5 in the control group and 82.1 ± 11.0 in the PRP group ( P = .699). The mean VAS scores were 1.4 ± 1.8 and 1.5 ± 2.1 in the control and PRP groups, respectively ( P = .910). None of the clinical assessments at 6, 12, and 24 months in either group produced statistically significant differences, and both groups showed significant improvements throughout the follow-up time in the 3 evaluations ( P < .001). The control group exhibited 1 full-thickness retear (Sugaya type IV) and 11 partial-thickness retears (Sugaya type III), while the PRP group had 7 partial-thickness retears (Sugaya type III). The overall number of retears did not differ between groups ( P = .203).

CONCLUSION

PRP obtained by apheresis and applied in liquid form with the addition of thrombin at the end of single-row repair of supraspinatus tears did not promote better clinical or structural results at 60-month follow-up.

REGISTRATION

NCT01029574 ( ClinicalTrials.gov identifier).

Platelet-rich plasma in fibrin matrix to augment rotator cuff repair: a prospective, single-blinded, randomized study with 2-year follow-up

BACKGROUND

Application of autologous platelet-rich plasma in fibrin matrix (PRPFM) improves tendon healing in patients undergoing arthroscopic rotator cuff repair. We performed a prospective, randomized, single-blinded study of 76 patients, with an α level of 5% and power of 80%.

MATERIALS AND METHODS

Seventy-six patients were divided into 2 randomized groups. The treatment group underwent arthroscopic rotator cuff repair with PRPFM. The control group did not receive the PRPFM treatment. Patients were evaluated preoperatively and at 6 months and 24 months postoperatively with validated clinical outcome scores, and dynamometer examination. A magnetic resonance imaging scan was performed at 6 months postoperatively.

RESULTS

The 2 randomized groups were homogeneous. Western Ontario Rotator Cuff (WORC) scores were not statistically different at any time interval. The WORC scores changed from 1257 to 139 in the control group and from 1106 to 99 in the PRPFM group over the 24-month study period. On the Simple Shoulder Test, improvement over the study period was noted from 45% to 96% in the control group and from 49% to 96% in the PRPFM group. Strength of the supraspinatus at 24 months by dynamometer testing was 99.8% in the control group and 96.3% in the PRPFM group. Infraspinatus strength was 104% in the control group and 103% in the PRPFM group. The secondary outcome of retear occurred at a rate of 19% for the double-row technique and 7.4% for the PRPFM technique at 6 months. All our results were statistically insignificant.

CONCLUSIONS

Our results showed no benefit from PRPFM used for rotator cuff repair according to the WORC Index, Simple Shoulder Test, and shoulder strength index.

Regenerative Potential of Platelet Rich Fibrin (PRF) for Curing Intrabony Periodontal Defects: A Systematic Review of Clinical Studies

Platelet-rich fibrin (PRF) has been used in regenerative medicine and dentistry. Recently, its use has been advocated for regenerative periodontics and wound healing. The randomized control trials have assessed the regenerative efficacy of the PRF for restoring intrabony periodontal defects. The objectives are to critically analyze and appraise the currently available literature, focusing on the use of PRF in regenerating periodontal bone defects. An electronic search was conducted (PubMed/MEDLINE, Google Scholar, ISI-WOS). Various combinations of following keywords were used: 'platelet-rich fibrin', 'intrabony', 'periodontal', 'bone defect' and 'guided tissue regeneration'. A secondary search was conducted by analyzing the reference lists of the articles obtained in initial search. The final search resulted in 13 randomized controlled trials being included. In majority of studies, PRF resulted in better clinical/radiographic outcomes than open flap debridement and augmented therapeutic effects of bone grafts. The combination of bovine bone substitutes and PRF resulted in better performance compared to alone. Similarly better outcomes were observed while using PRF in combination with nanohydroxyapatite, metformin and demineralized freeze-dried bone allograft. It can be concluded that PRF produces better outcomes than open flap debridement alone and augments the regenerative effects of bone substitutes.

The biology of rotator cuff healing

Despite advances in surgical reconstruction of chronic rotator cuff (RC) tears leading to improved clinical outcomes, failure rates of 13-94% have been reported. Reasons for this rather high failure rate include compromised healing at the bone-tendon interface, as well as the musculo-tendinous changes that occur after RC tears, namely retraction and muscle atrophy, as well as fatty infiltration. Significant research efforts have focused on gaining a better understanding of these pathological changes in order to design effective therapeutic solutions. Biological augmentation, including the application of different growth factors, platelet concentrates, cells, scaffolds and various drugs, or a combination of the above have been studied. It is important to note that instead of a physiological enthesis, an abundance of scar tissue is formed. Even though cytokines have demonstrated the potential to improve rotator cuff healing in animal models, there is little information about the correct concentration and timing of the more than 1500 cytokines that interact during the healing process. There is only minimal evidence that platelet concentrates may lead to improvement in radiographic, but not clinical outcome. Using stem cells to biologically augment the reconstruction of the tears might have a great potential since these cells can differentiate into various cell types that are integral for healing. However, further studies are necessary to understand how to enhance the potential of these stem cells in a safe and efficient way. This article intends to give an overview of the biological augmentation options found in the literature.

Advances in biologic augmentation for rotator cuff repair

Rotator cuff tear is a very common shoulder injury that often necessitates surgical intervention for repair. Despite advances in surgical techniques for rotator cuff repair, there is a high incidence of failure after surgery because of poor healing capacity attributed to many factors. The complexity of tendon-to-bone integration inherently presents a challenge for repair because of a large biomechanical mismatch between the tendon and bone and insufficient regeneration of native tissue, leading to the formation of fibrovascular scar tissue. Therefore, various biological augmentation approaches have been investigated to improve rotator cuff repair healing. This review highlights recent advances in three fundamental approaches for biological augmentation for functional and integrative tendon-bone repair. First, the exploration, application, and delivery of growth factors to improve regeneration of native tissue are discussed. Second, applications of stem cell and other cell-based therapies to replenish damaged tissue for better healing are covered. Finally, this review will highlight the development and applications of compatible biomaterials to both better recapitulate the tendon-bone interface and improve delivery of biological factors for enhanced integrative repair.

Growth factor and pro-inflammatory cytokine contents in platelet-rich plasma (PRP), plasma rich in growth factors (PRGF), advanced platelet-rich fibrin (A-PRF), and concentrated growth factors (CGF)

Background

The development of platelet-rich fibrin (PRF) drastically simplified the preparation procedure of platelet-concentrated biomaterials, such as platelet-rich plasma (PRP), and facilitated their clinical application. PRF’s clinical effectiveness has often been demonstrated in pre-clinical and clinical studies; however, it is still controversial whether growth factors are significantly concentrated in PRF preparations to facilitate wound healing and tissue regeneration. To address this matter, we performed a comparative study of growth factor contents in PRP and its derivatives, such as advanced PRF (A-PRF) and concentrated growth factors (CGF).

Methods

PRP and its derivatives were prepared from the same peripheral blood samples collected from healthy donors. A-PRF and CGF preparations were homogenized and centrifuged to produce extracts. Platelet and white blood cell counts in A-PRF and CGF preparations were determined by subtracting those counts in red blood cell fractions, supernatant acellular serum fractions, and A-PRF/CGF exudate fractions from those counts of whole blood samples. Concentrations of growth factors (TGF-β1, PDGF-BB, VEGF) and pro-inflammatory cytokines (IL-1β, IL-6) were determined using ELISA kits.

Results

Compared to PRP preparations, both A-PRF and CGF extracts contained compatible or higher levels of platelets and platelet-derived growth factors. In a cell proliferation assay, both A-PRF and CGF extracts significantly stimulated the proliferation of human periosteal cells without significant reduction at higher doses.

Conclusions

These data clearly demonstrate that both A-PRF and CGF preparations contain significant amounts of growth factors capable of stimulating periosteal cell proliferation, suggesting that A-PRF and CGF preparations function not only as a scaffolding material but also as a reservoir to deliver certain growth factors at the site of application.

SECEC Research Grant 2008 II: Use of platelet- and leucocyte-rich fibrin (L-PRF) does not affect late rotator cuff tendon healing: a prospective randomized controlled study

BACKGROUND

Because the retear rate after rotator cuff repairs remains high, methods to improve healing are very much needed. Platelet-rich concentrates have been shown to enhance tenocyte proliferation and promote extracellular matrix synthesis in vitro; however, their clinical benefit remains unclear. We hypothesized that arthroscopic rotator cuff repair with leucocyte- and platelet-rich fibrin (L-PRF) results in better clinical and radiographic outcome at 12 months of follow-up than without L-PRF.

METHODS

Thirty-five patients were randomized to receive arthroscopic rotator cuff repair with L-PRF locally applied to the repair site (L-PRF+ group, n = 17) or without L-PRF (L-PRF- group, n = 18). Preoperative and postoperative clinical evaluation included the Subjective Shoulder Value, visual analog score for pain, Simple Shoulder Test, and Constant-Murley score. The anatomic watertight healing, tendon thickness, and tendon quality was evaluated using magnetic resonance arthrography at 12 months of follow-up.

RESULTS

No complications were reported in either group. The mean Subjective Shoulder Value, Simple Shoulder Test, and Constant-Murley scores increased from preoperatively to postoperatively, showing no significant differences between the groups. Complete anatomic watertight healing was found in 11 of 17 in the L-PRF+ group and in 11 of 18 in the L-PRP- group (P = .73). The mean postoperative defect size (214 ± 130 mm(2) in the L-PRF+ group vs 161 ± 149 mm(2) in the L-PRF- group; P = .391) and the mean postoperative tendon quality according to Sugaya (L-PRF+ group: 3.0 ± 1.4, L-PRF- group: 3.0 ± 0.9) were similar in both groups at 12 months of follow-up.

CONCLUSION

Arthroscopic rotator cuff repair with application of L-PRF yields no beneficial effect in clinical outcome, anatomic healing rate, mean postoperative defect size, and tendon quality at 12 months of follow-up.

Concentrated growth factor increases Schwann cell proliferation and neurotrophic factor secretion and promotes functional nerve recovery in vivo

Concentrated growth factor (CGF) is a newly generated complex that comprises a fibrin matrix incorporating growth factors and plasmatic and leukocyte cytokines. It has been widely used in bone regenerative medicine. However, the effect of CGF on peripheral nerve regeneration had not been previously investigated. The aim of the present study was to evaluate the possibility of using CGF for nerve regeneration by i) investigating the effect of CGF on the proliferation of Schwann cells (SCs) and secretion of neurotrophic factors nerve growth factor (NGF) and glial cell line‑derived neurotrophic factor (GDNF) in vitro; and ii) analyzing the effect of CGF on functional nerve recovery after nerve injury in vivo. CGF was prepared from venous blood taken from rats, and using scanning electron microscopy (SEM) we noted that it featured a fiber‑like appearance with pore size ranging from 0.1 to 1.0 µm. The soluble component of CGF was used to produce conditioned media with which to treat the Schwann cell line. A cell counting kit-8 assay and cell cycle analysis were both used to study the proliferative effect of CGF on SCs. Reverse transcription-quantitative PCR and western blot analysis demonstrated that there was an increase in the mRNA and protein expression of NGF and GDNF, both of which are markers of SC neurotrophic secretion. A model of sciatic nerve crush injury was established for the in vivo experiment, and CGF was found to increase the sciatic functional index (indicative of nerve function). We noted that CGF increased SC proliferation and secretion of neurotrophic factors in vitro, and promoted functional recovery after peripheral nerve injuries in vivo. These results suggest that CGF is a promising candidate biomaterial for peripheral nerve regeneration, and may potentially be utilized to repair nerve injuries.

Influence of Leukocyte- and Platelet-Rich Fibrin (L-PRF) in the Healing of Simple Postextraction Sockets: A Split-Mouth Study

The aim of this study was to evaluate the effects of leukocyte- and platelet-rich fibrin (L-PRF) on the pain and soft tissue healing after tooth extractions. Twenty-six patients (9 males and 17 females) were treated with multiple extractions (2 to 8), with a total of 108 extractions. This was an exploratory single blinded randomized clinical trial with a split-mouth design. The pain after the surgery was assessed in each patient by the VAS scale (1 to 10) at intervals of 24-48-72-96 hours. The soft tissue healing was clinically evaluated at 3, 7, 14, and 21 days after surgery by the same examiner surgeon, using the modified Healing Index (4 to 12). The mean value of postextraction pain was 3.2 ± 0.3 in the experimental sides and 4.1 ± 0.1 in the control sides. After 7 days from the extractions, the values of modified Healing Index in the experimental and control groups were, respectively, 4.8 ± 0.6 and 5.1 ± 0.9. The use of L-PRF in postextraction sockets filling can be proposed as a useful procedure in order to manage the postoperative pain and to promote the soft tissue healing process, reducing the early adverse effects of the inflammation.

PRP and articular cartilage: a clinical update

The convincing background of the recent studies, investigating the different potentials of platelet-rich plasma, offers the clinician an appealing alternative for the treatment of cartilage lesions and osteoarthritis. Recent evidences in literature have shown that PRP may be helpful both as an adjuvant for surgical treatment of cartilage defects and as a therapeutic tool by intra-articular injection in patients affected by osteoarthritis. In this review, the authors introduce the trophic and anti-inflammatory properties of PRP and the different products of the available platelet concentrates. Then, in a complex scenario made of a great number of clinical variables, they resume the current literature on the PRP applications in cartilage surgery as well as the use of intra-articular PRP injections for the conservative treatment of cartilage degenerative lesions and osteoarthritis in humans, available as both case series and comparative studies. The result of this review confirms the fascinating biological role of PRP, although many aspects yet remain to be clarified and the use of PRP in a clinical setting has to be considered still exploratory.

Platelet-rich concentrates differentially release growth factors and induce cell migration in vitro

BACKGROUND

Platelet-rich concentrates are used as a source of growth factors to improve the healing process. The diverse preparation protocols and the gaps in knowledge of their biological properties complicate the interpretation of clinical results.

QUESTIONS/PURPOSES

In this study we aimed to (1) analyze the concentration and kinetics of growth factors released from leukocyte- and platelet-rich fibrin (L-PRF), leukocyte- and platelet-rich plasma (L-PRP), and natural blood clot during in vitro culture; (2) investigate the migration of mesenchymal stem cells (MSCs) and human umbilical vein endothelial cells (HUVECs) as a functional response to the factors released; and (3) uncover correlations between individual growth factors with the initial platelet/leukocyte counts or the induced cell migration.

METHODS

L-PRF, L-PRP, and natural blood clot prepared from 11 donors were cultured in vitro for 28 days and media supernatants collected after 8 hours and 1, 3, 7, 14, and 28 days. Released transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), insulin growth factor (IGF-1), platelet-derived growth factor AB (PDGF-AB), and interleukin-1β (IL-1β) were measured in the supernatants with enzyme-linked immunosorbent assay. Migration of MSC and HUVEC induced by the supernatants was evaluated in Boyden chambers.

RESULTS

More TGF-ß1 was released (mean ± SD in pg/mL of blood) from L-PRF (37,796 ± 5492) compared with L-PRP (23,738 ± 6848; p < 0.001) and blood clot (3739 ± 4690; p < 0.001), whereas more VEGF and IL-1ß were released from blood clot (1933 ± 704 and 2053 ± 908, respectively) compared with both L-PRP (642 ± 208; p < 0.001 and 273 ± 386; p < 0.001, respectively) and L-PRF (852 ± 376; p < 0.001 and 65 ± 56, p < 0.001, respectively). No differences were observed in IGF-1 and PDGF-AB released from any of the concentrates. TGF-β1 release peaked at Day 7 in L-PRF and at 8 hours and Day 7 in L-PRP and 8 hours and Day 14 in blood clot. In all concentrates, main release of VEGF occurred between 3 and 7 days and of IL-1β between Days 1 and 7. IGF-1 and PDGF-AB were released until Day 1 in L-PRP and blood clot, in contrast to sustained release over the first 3 days in L-PRF. The strongest migration of MSC occurred in response to L-PRF, and more HUVEC migration was seen in L-PRF and blood clot compared with L-PRP. TGF-β1 correlated with initial platelet counts in L-PRF (Pearson r = 0.66, p = 0.0273) and initial leukocyte counts in L-PRP (Pearson r = 0.83, p = 0.0016). A positive correlation of IL-1β on migration of MSC and HUVEC was revealed (Pearson r = 0.16, p = 0.0208; Pearson r = 0.31, p < 0.001).

CONCLUSIONS

In comparison to L-PRP, L-PRF had higher amounts of released TGF-β1, a long-term release of growth factors, and stronger induction of cell migration. Future preclinical studies should confirm these data in a defined injury model.

CLINICAL RELEVANCE

By characterizing the biologic properties of different platelet concentrates in vitro, we may gain a better understanding of their clinical effects and develop guidelines for specific future applications.

Dynamic Intraligamentary Stabilization (DIS) for treatment of acute anterior cruciate ligament ruptures: case series experience of the first three years

Background

In recent years, the scientific discussion has focused on new strategies to enable a torn anterior cruciate ligament (ACL) to heal into mechanically stable scar tissue. Dynamic intraligamentary stabilization (DIS) was first performed in a pilot study of 10 patients. The purpose of the current study was to evaluate whether DIS would lead to similarly sufficient stability and good clinical function in a larger case series.

Methods

Acute ACL ruptures were treated by using an internal stabilizer, combined with anatomical repositioning of torn bundles and microfracturing to promote self-healing. Clinical assessment (Tegner, Lysholm, IKDC, and visual analogue scale [VAS] for patient satisfaction scores) and assessment of knee laxity was performed at 3, 6, 12, and 24 months. A one-sample design with a non-inferiority margin was chosen to compare the preoperative and postoperative IKDS and Lysholm scores.

Results

278 patients with a 6:4 male to female ratio were included. Average patient age was 31 years. Preoperative mean IKDC, Lysholm, and Tegner scores were 98.8, 99.3, and 5.1 points, respectively. The mean anteroposterior (AP) translation difference from the healthy contralateral knee was 4.7 mm preoperatively. After DIS treatment, the mean 12-month IKDC, Lysholm, and Tegner scores were 93.6, 96.2, and 4.9 points, respectively, and the mean AP translation difference was 2.3 mm. All these outcomes were significantly non-inferior to the preoperative or healthy contralateral values (p < 0.0001). Mean patient satisfaction was 8.8 (VAS 0–10). Eight ACL reruptures occurred and 3 patients reported insufficient subjective stability of the knee at the end of the study period.

Conclusions

Anatomical repositioning, along with DIS and microfracturing, leads to clinically stable healing of the torn ACL in the large majority of patients. Most patients exhibited almost normal knee function, reported excellent satisfaction, and were able to return to their previous levels of sporting activity. Moreover, this strategy resulted in stable healing of all sutured menisci, which could lower the rate of osteoarthritic changes in future. The present findings support the discussion of a new paradigm in ACL treatment based on preservation and self-healing of the torn ligament.