Lyophilised Platelet-Rich Fibrin: Physical and Biological Characterisation

Platelet-rich fibrin as an autologous biomaterial for bone regeneration: mechanisms, applications, optimization

Platelet-rich fibrin, a classical autologous-derived bioactive material, consists of a fibrin scaffold and its internal loading of growth factors, platelets, and leukocytes, with the gradual degradation of the fibrin scaffold and the slow release of physiological doses of growth factors. PRF promotes vascular regeneration, promotes the proliferation and migration of osteoblast-related cells such as mesenchymal cells, osteoblasts, and osteoclasts while having certain immunomodulatory and anti-bacterial effects. PRF has excellent osteogenic potential and has been widely used in the field of bone tissue engineering and dentistry. However, there are still some limitations of PRF, and the improvement of its biological properties is one of the most important issues to be solved. Therefore, it is often combined with bone tissue engineering scaffolds to enhance its mechanical properties and delay its degradation. In this paper, we present a systematic review of the development of platelet-rich derivatives, the structure and biological properties of PRF, osteogenic mechanisms, applications, and optimization to broaden their clinical applications and provide guidance for their clinical translation.

Lyophilized platelet rich fibrin and gelatin incorporated bioadhesive bone cement composite for repair of mandibular continuity defects

Mandibular continuity defects stem from conditions such as malignancies, trauma, cysts, osteomyelitis and osteoradionecrosis, presenting significant challenges. If mandibular reconstruction fails, it can result in facial collapse, causing significant aesthetic and functional concerns for the patient. In the present study we developed a bio-adhesive Bone Cement (BC) enriched with lyophilised PRF and gelatin to enhance bone repair and induce regeneration. The developed BC consisted of a mixture of Tetracalcium Phosphate (TTCP) and O-Phospho-l-serine (OPLS) in addition to lyophilised Platelet Rich Fibrin (PRF) for sustained growth factor release and gelatin (GE) for improved cement resorption. It is primarily designed for in-situ application, conforming to the shape and size of the defect for effective bone repair and regeneration. The study evaluated four groups: (i) BC (control), (ii) BC-GE (control), (iii) BC-PRF, and (iv) BC-GE-PRF. All the four groups were characterised using FTIR, SEM and XRD. The mechanical studies of the prepared beads exhibited a significant increase in the compressive strength of the PRF loaded bone cement composites. In vitro degradation study of the beads over a 60-day period revealed a significantly higher percentage of bone cement resorption in the gelatin-incorporated groups, BC-GE (44 ± 0.5 %), and BC-GE-PRF (45 ± 2 %). The assessment of growth factor release (TGF-β and VEGF) using ELISA revealed a prolonged and sustained release of both growth factors over a 28-day period. In vitro studies were performed on human Dental Follicle Stem Cells (DFSCs) to assess cell attachment, proliferation, mineralisation and osteogenic differentiation. These studies clearly depicted that BC-PRF and BC-GE-PRF showed significantly greater proliferation of DFSCs. Furthermore, BC-PRF and BC-GE-PRF samples exhibited notably elevated expression of Runx2 and OPN (osteogenic markers), as well as a higher intensity of alizarin red stain (mineralisation). Therefore, it was concluded that PRF incorporated bioadhesive bone cement composites greatly enhance the cell attachment, proliferation, mineralisation and osteogenic differentiation of the DFSCs. Thus, the PRF and gelatin incorporated bone cement composites is expected to facilitate effective and faster bone regeneration and healing in a wide range of dental and maxillofacial defects.

THERAPEUTIC EFFECT OF USING AUTOLOGOUS PLATELET CONCENTRATE IN VITRECTOMY FOR MACULAR HOLE: A Systematic Review and Meta-Analysis

PURPOSE

To summarize the current evidence regarding the therapeutic effect of using autologous platelet concentrate (APC) in vitrectomy for macular hole (MH).

METHODS

The PubMed, Web of Science, and Embase databases were searched according to the PROSPERO protocol (CRD42022366202). Controlled trials comparing whether APC was used in the vitrectomy of MH were included. The primary outcome was the closure rate of MH and postoperative best-corrected visual acuity, and the secondary outcome was the incidence of different types of complications.

RESULTS

Seven studies that included 634 eyes were eligible. For the primary outcome, the usage of APC significantly improved the closure rate of MH in vitrectomy (odds ratio [OR] = 5.34, 95% confidence interval, 2.83-10.07, P < 0.001). Postoperative visual acuity did not significantly differ between the APC group and similar baseline controls (SMD = -0.07, 95% confidence interval, -0.35 to 0.22, P = 0.644). For the secondary outcome, using APC did not result in additional complications regarding postoperative retinal detachment or the recurrence of MH.

CONCLUSION

The use of APC in vitrectomy was associated with a superior closure rate of the hole and no additional complications; therefore, it is effective and safe in MH surgery.

3D printing of 'green' thermo-sensitive chitosan-hydroxyapatite bone scaffold based on lyophilized platelet-rich fibrin

The critical bone defect is still an urgent problem in the field of bone repair. Here, we reported a new type of chitosan (CS)-hydroxyapatite (HAP) scaffolds based on lyophilized platelet-rich fibrin (L-PRF) for releasing abundant growth factors to realize their respective functions. It also has strong mechanical properties to maintain the stability of the bone repair environment. However, acid-soluble CS hydrogels often contain toxic and organic solvents. Moreover, chemical agents may be used for cross-linking for better mechanical properties, further increasing cytotoxicity. In this study, we used an alkali/urea dissolution system to dissolve CS, which improved its mechanical properties and made it thermo-sensitive. Finally, the L-PRF-CS-HAP (P-C-H) composite scaffold was constructed by extrusion-based printing. The results showed that the printing ink had desirable printability and temperature sensitivity. The compressive properties of the scaffolds exhibited a trend of decline with L-PRF content increasing, but all of them could meet the strength of cancellous bone. Meanwhile, the scaffolds had high hydrophilicity, porosity, and could be degraded stablyin vitro. The antibacterial properties of the scaffolds were also verified, greatly reducing the risk of infection during bone repair. It was also demonstrated that the release time of growth factor from L-PRF was significantly prolonged, and growth factor could still be detected after 35 d of sustained release. The capacity of cells to proliferate increased as the number of L-PRF components increased, indicating that L-PRF still exhibited biological activity after 3D printing.

Rescuing “hopeless” avulsed teeth using autologous platelet-rich fibrin following delayed reimplantation: Two case reports

BACKGROUND

Tooth avulsion is one of the most severe types of dental trauma. Most avulsed teeth undergo long-term ankylosis and replacement resorption after delayed reimplantation and exhibit a poor prognosis. The aim of this work was to improve the success rate of avulsed teeth after delayed reimplantation using autologous platelet-rich fibrin (PRF).

CASE SUMMARY

Case 1 was a 14-year-old boy who fell and knocked out his left upper central incisor 18 h prior to his arrival at the department. The diagnoses were avulsion of tooth 21, lateral luxation of tooth 11 and alveolar fracture of teeth 11 and 21. In case 2, a 17-year-old boy fell 2 h prior to his presentation to the hospital, and his left upper lateral incisor was completely knocked out of the alveolar socket. The diagnoses included avulsion of tooth 22, complicated crown fracture of tooth 11 and complicated crown-root fracture of tooth 21. The avulsed teeth were reimplanted along with autologous PRF granules and splinted using a semiflexible titanium preshaped labial arch. The root canals of the avulsed teeth were filled with calcium hydroxide paste, and root canal filling was performed 4 wk after reimplantation. The reimplanted teeth showed no symptoms of inflammatory root resorption or ankylosis at the 3-, 6-, and 12-mo follow-up examinations after reimplantation with autologous PRF. In addition to the avulsed teeth, the other injured teeth were treated using corresponding conventional treatment methods.

CONCLUSION

These cases provide examples of the successful use of PRF to reduce pathological root resorption of the avulsed teeth, and the application of PRF may provide new healing opportunities for traditionally “hopeless” avulsed teeth.

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.

Effect of Currently Available Nanoparticle Synthesis Routes on Their Biocompatibility with Fibroblast Cell Lines

Nanotechnology has acquired significance in dental applications, but its safety regarding human health is still questionable due to the chemicals utilized during various synthesis procedures. Titanium nanoparticles were produced by three novel routes, including Bacillus subtilis, Cassia fistula and hydrothermal heating, and then characterized for shape, phase state, size, surface roughness, elemental composition, texture and morphology by SEM, TEM, XRD, AFM, DRS, DLS and FTIR. These novel titanium nanoparticles were tested for cytotoxicity through the MTT assay. L929 mouse fibroblast cells were used to test the cytotoxicity of the prepared titanium nanoparticles. Cell suspension of 10% DMEM with 1 × 104 cells was seeded in a 96-well plate and incubated. Titanium nanoparticles were used in a 1 mg/mL concentration. Control (water) and titanium nanoparticles stock solutions were prepared with 28 microliters of MTT dye and poured into each well, incubated at 37 °C for 2 h. Readings were recorded on day 1, day 15, day 31, day 41 and day 51. The results concluded that titanium nanoparticles produced by Bacillus subtilis remained non-cytotoxic because cell viability was >90%. Titanium nanoparticles produced by Cassia fistula revealed mild cytotoxicity on day 1, day 15 and day 31 because cell viability was 60−90%, while moderate cytotoxicity was found at day 41 and day 51, as cell viability was 30−60%. Titanium nanoparticles produced by hydrothermal heating depicted mild cytotoxicity on day 1 and day 15; moderate cytotoxicity on day 31; and severe cytotoxicity on day 41 and day 51 because cell viability was less than 30% (p < 0.001). The current study concluded that novel titanium nanoparticles prepared by Bacillus subtilis were the safest, more sustainable and most biocompatible for future restorative nano-dentistry purposes.

In Vitro Assessment of Lyophilized Advanced Platelet-Rich Fibrin from Dogs in Promotion of Growth Factor Release and Wound Healing

Advanced platelet-rich fibrin (A-PRF) induces more proliferation and migration of fibroblasts compared with standard PRF, but it being freshly prepared prior to it being applied is necessary. Therefore, this study aimed to determine the effect of lyophilized A-PRF on growth factor release and cell biological activity. Blood samples were collected from six dogs and processed for fresh and lyophilized A-PRF. The growth factors released included transforming growth factor beta-1 (TGF-β1), vascular endothelial growth factor-A (VEGFA), and platelet-derived growth factor-BB (PDGF-BB), and the fibroblast proliferation as well as wound closure enhancement of both products were compared. The results showed that TGF-β1, PDGF-BB, and VEGFA were continually released from lyophilized A-PRF for over 72 h. Lyophilized A-PRF released significantly more accumulated VEGEA and a tendency to release more TGF-β1 at 72 h as well as VEGFA at 24 h and 72 h than fresh A-PRF. Moreover, lyophilized A-PRF increased fibroblast proliferation and induced a significantly faster wound closure than the control, while no significant difference between fresh and lyophilized A-PRF was found. In conclusion, the lyophilization of canine A-PRF can preserve the release of growth factors and has similar biological activities to a fresh preparation. This encourages the substitution of lyophilized A-PRF instead of fresh A-PRF in regenerative treatments in which the stability of the product is concerned.

Third-Generation Platelet Concentrates in Periodontal Regeneration: Gaining Ground in the Field of Regeneration

Platelets are important for hemostasis and the healing of wounds. In clinical settings, healing cytokines including insulin-like growth factors (IGF), platelet-derived growth factors (PDGF), and transforming growth factors (TGF) are commonly implemented. The regenerative approach in dentistry frequently employs platelet concentrates (PCs) that are “autologous in origin” and have a high concentration of platelets, growth factors, and leukocytes. First-generation PCs is made of platelet-rich plasma (PRP), while second-generation PC is made of platelet-rich fibrin (PRF). Both have limitations, so modification protocols and development in PRP and PRF derivatives are required for advancement mechanisms, strength, biodegradability, retention ability in the field of regenerative dentistry, and so on. As third-generation PC, newer genera kinds of PRF, such as advanced-PRF (A-PRF), advanced-PRF+ (A-PRF+), injectable-PRF (i-PRF), and titanium-PRF (T-PRF), were introduced. A-PRF matrices in their solid form were introduced using the low-speed centrifugation concept (LSCC). The applied relative centrifugal force (RCF) for A-PRF is reduced to 208 g as a result of this improved preparation process. A-PRF features a greater number of neutrophil granules in the distal region, especially at the red blood cells-buffer coat (RBC-BC) interface, and the A-PRF clot has a more porosity-like structure with a bigger interfibrous space than PRF. Since the PRF is in a gel form and is difficult to inject, i-PRF was formulated to address this problem. Compared to the other two protocols, the i-PRF protocol requires far less time, and this is the advantage of this PC. This is because i-PRF just needs the blood components to be separated, which happens within the first two to four minutes. Compared to normal L-PRF, T-PRF creates fibrin that is thicker and more densely woven. Titanium has a higher hemocompatibility than glass, which could lead to greater polymerized fibrin formation. In periodontal regenerative operations, oral surgery, and implant dentistry, PRF and its newer advanced modifications have demonstrated promising results and desirable results in both soft and hard tissue regenerative techniques.

Insights Into the Role of Platelet-Derived Growth Factors: Implications for Parkinson’s Disease Pathogenesis and Treatment

Parkinson’s disease (PD), the second most common neurodegenerative disease after Alzheimer’s disease, commonly occurs in the elderly population, causing a significant medical and economic burden to the aging society worldwide. At present, there are few effective methods that achieve satisfactory clinical results in the treatment of PD. Platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFRs) are important neurotrophic factors that are expressed in various cell types. Their unique structures allow for specific binding that can effectively regulate vital functions in the nervous system. In this review, we summarized the possible mechanisms by which PDGFs/PDGFRs regulate the occurrence and development of PD by affecting oxidative stress, mitochondrial function, protein folding and aggregation, Ca2+ homeostasis, and cell neuroinflammation. These modes of action mainly depend on the type and distribution of PDGFs in different nerve cells. We also summarized the possible clinical applications and prospects for PDGF in the treatment of PD, especially in genetic treatment. Recent advances have shown that PDGFs have contradictory roles within the central nervous system (CNS). Although they exert neuroprotective effects through multiple pathways, they are also associated with the disruption of the blood–brain barrier (BBB). Our recommendations based on our findings include further investigation of the contradictory neurotrophic and neurotoxic effects of the PDGFs acting on the CNS.