Changes in platelet-rich fibrin composition after trauma and surgical intervention

Characterization of Fat Used for the Optimization of the Soft Tissue Envelope of the Nose in Rhinoplasty

Septorhinoplasty (SRP) is one of the most common aesthetic procedures worldwide. A thin or scarred soft tissue envelope, especially in the context of secondary SRP, can lead to unpredictable scarring, shrinkage, and discoloration of the skin. Other than the careful preparation of the soft tissue mantle, no gold standard exists to minimize the above-mentioned risks. Our aim was to create a thin "separation layer" between the nasal bridge (osseous and cartilaginous) and the skin envelope by autologous fat transfer with the addition of platelet-rich fibrin (PRF) to conceal small irregularities, to improve the quality of the skin soft tissue mantle, and to optimize the mobility of the skin. We report 21 patients who underwent SRP on a voluntary basis. All patients had either thin skin and/or revision SRP with scarring. Macroscopic fat harvested from the periumbilical or rib region was minced and purified. PRF was obtained by centrifugation of autologous whole blood samples and mixed with the fat to form a graft, which was then transferred to the nasal dorsum. Postoperative monitoring of graft survival included sonography and magnetic resonance imaging (MRI) of the nose. The harvested adipose tissue was also analyzed in vitro. In the postoperative follow-up after 1 year, survival of the adipose tissue was demonstrated in all patients by both sonography and MRI. The in vitro analysis showed interindividual differences in the quantity, size, and quality of the transplanted adipocytes. Camouflage of the nasal bridge by using adipose tissue was beneficial for the quality of the skin soft tissue mantle and hence represents a good alternative to known methods. Future aims include the ability to assess the quality of adipose tissue to be transplanted based on clinical parameters. Level of evidence: N/A.

Autologous Platelet and Extracellular Vesicle-Rich Plasma as Therapeutic Fluid: A Review

The preparation of autologous platelet and extracellular vesicle-rich plasma (PVRP) has been explored in many medical fields with the aim to benefit from its healing potential. In parallel, efforts are being invested to understand the function and dynamics of PVRP that is complex in its composition and interactions. Some clinical evidence reveals beneficial effects of PVRP, while some report that there were no effects. To optimize the preparation methods, functions and mechanisms of PVRP, its constituents should be better understood. With the intention to promote further studies of autologous therapeutic PVRP, we performed a review on some topics regarding PVRP composition, harvesting, assessment and preservation, and also on clinical experience following PVRP application in humans and animals. Besides the acknowledged actions of platelets, leukocytes and different molecules, we focus on extracellular vesicles that were found abundant in PVRP.

Growth Factor Release within Liquid and Solid PRF

Aim: The purpose of this study was to obtain data concerning growth factor release within liquid and solid platelet-rich fibrin (PRF) matrices and to estimate the amount of potential interindividual variations as a basis for further preclinical and clinical trials. Therefore, we aimed to determine possible differences in the release of growth factors between liquid and solid PRF. Materials and Methods: Blood samples obtained from four subjects were processed to both liquid and solid PRF matrices using a standard centrifugation protocol. Five growth factors (vascular endothelial growth factor, VEGF; epidermal growth factor, EGF; platelet-derived growth factor-BB, PDGF-BB; transforming growth factor-β1, TGF-β1; and matrix metallopeptidase 9, MMP-9) have been evaluated at six time points by ELISA over a total observation period of 10 days (1 h, 7 h, 1 d, 2 d, 7 d, and 10 d). Results: Growth factor release could be measured in all samples at each time point. Comparing liquid and solid PRF matrices, no significant differences were detected (p > 0.05). The mean release of VEGF, TGFβ-1, PDGF-BB, and MMP-9 raised to a peak at time point five (day 7) in both liquid and solid PRF matrices. VEGF release was lower in liquid PRF than in solid PRF, whereas those of PDGF-BB and MMP-9 were higher in liquid PRF than in solid PRF at all time points. EGF had its peak release already at time point two after 7 h in liquid and solid matrices (hour 7 EGF solid: mean = 180 pg/mL, SD = 81; EGF liquid: mean = 218 pg/mL, SD = 64), declined rapidly until day 2, and had a second slight peak on day 7 in both groups (day 7 EGF solid: mean = 182 pg/mL, SD = 189; EGF liquid: mean = 81 pg/mL, SD = 70). Conclusions: This study detected growth factor release within liquid and solid PRF matrices with little variations. Further preclinical trials are needed to precisely analyze the growth factor release in larger samples and to better understand their effects on wound healing in different clinical indications.

The feasibility of injectable PRF (I-PRF) for bone tissue engineering and its application in oral and maxillofacial reconstruction: From bench to chairside

Among all the biomaterials introduced in the field of bone tissue engineering, injectable platelet-rich fibrin (I-PRF) has recently gained considerable attention. I-PRF, as a rich source of biologically active molecules, is a potential candidate which can be easily obtained in bedside and constitutes several biological factors which can result in higher anti-bacterial, anti-inflammatory and regenerative capabilities. According to the studies evaluating the osteogenic efficacy of I-PRF, this biomaterial has exhibited favorable outcomes in terms of adhesion, differentiation, migration, proliferation and mineralization potential of stem cells. In addition, the injectability and ease-of-applicability of this biomaterial has led to its various clinical applications in the oral and maxillofacial bone regeneration such as ridge augmentation, sinus floor elevation, cleft palate reconstruction and so on. Furthermore, to enhance the clinical performance of I-PRF, albumin gel-PRF as a long-lasting material for long-term utilization has been recently introduced with a gradual increase in growth factor release pattern. This review provides a comprehensive approach to better evaluate the applicability of I-PRF by separately appraising its performance in in-vitro, in-vivo and clinical situations. The critical approach of this review toward the different production protocols and different physical and biological aspects of I-PRF can pave the way for future studies to better assess the efficacy of I-PRF in bone regeneration.

Optimization of the Soft Tissue Envelope of the Nose in Rhinoplasty Utilizing Fat Transfer Combined with Platelet-Rich Fibrin

A thin or damaged skin soft tissue envelope may cause concerns in primary and secondary rhinoplasty. During postoperative healing, unpredictable scarring and contraction may occur and lead to significant aesthetic and trophic sequelae. Besides a meticulous surgical technique, there are no reliable techniques to prevent long-term skin damage and shrinkage. Fat transfer with addition of platelet-rich fibrin (PRF) harbors the possibility of local soft tissue regeneration and skin rejuvenation through growth factors and mesenchymal stem cells. It may also facilitate the creation of a thin fat layer on the dorsum to prevent shrink-wrap forces and conceal small irregularities. The goal is to provide evidence for the feasibility, durability, and beneficial effect of diced macrofat transfer bonded with PRF on the nasal dorsum. We present the technique of fat transfer conjugated with PRF as a nasal dorsal graft. Clinical endpoints were the prevention of trophic disturbances and atrophy at a 1-year postoperative follow-up. We present the skin mobility test as a clinical indicator of a healthy soft tissue envelope. The presented case series consists of 107 rhinoplasties. Fat was harvested in the umbilical or costal region. PRF was created by centrifugation of autologous whole blood samples. Macrofat was diced, cleaned, and bonded with PRF. The compound transplants were transferred to the nasal dorsum. There were no perioperative complications or wound-healing issues. Mean follow-up was 14 months. Clinical inspection showed good skin quality and no signs of shrinkage, marked scarring, or color changes with positive skin mobility test in all patients. Survival of fat was confirmed by ultrasonography and magnetic resonance imaging. Diced macrofat transfer in conjunction with PRF to the nasal dorsum is a feasible and safe method. A beneficial effect on the soft tissue envelope is demonstrated as well as the prevention of shrink-wrap forces.

First Human Leucocyte Antigen (HLA) Response and Safety Evaluation of Fibrous Demineralized Bone Matrix in a Critical Size Femoral Defect Model of the Sprague-Dawley Rat

Treatment of large bone defects is one of the great challenges in contemporary orthopedic and traumatic surgery. Grafts are necessary to support bone healing. A well-established allograft is demineralized bone matrix (DBM) prepared from donated human bone tissue. In this study, a fibrous demineralized bone matrix (f-DBM) with a high surface-to-volume ratio has been analyzed for toxicity and immunogenicity. f-DBM was transplanted to a 5-mm, plate-stabilized, femoral critical-size-bone-defect in Sprague-Dawley (SD)-rats. Healthy animals were used as controls. After two months histology, hematological analyses, immunogenicity as well as serum biochemistry were performed. Evaluation of free radical release and hematological and biochemical analyses showed no significant differences between the control group and recipients of f-DBM. Histologically, there was no evidence of damage to liver and kidney and good bone healing was observed in the f-DBM group. Reactivity against human HLA class I and class II antigens was detected with mostly low fluorescence values both in the serum of untreated and treated animals, reflecting rather a background reaction. Taken together, these results provide evidence for no systemic toxicity and the first proof of no basic immunogenic reaction to bone allograft and no sensitization of the recipient.

3D-Printing of Hierarchically Designed and Osteoconductive Bone Tissue Engineering Scaffolds

In Bone Tissue Engineering (BTE), autologous bone-regenerative cells are combined with a scaffold for large bone defect treatment (LBDT). Microporous, polylactic acid (PLA) scaffolds showed good healing results in small animals. However, transfer to large animal models is not easily achieved simply by upscaling the design. Increasing diffusion distances have a negative impact on cell survival and nutrition supply, leading to cell death and ultimately implant failure. Here, a novel scaffold architecture was designed to meet all requirements for an advanced bone substitute. Biofunctional, porous subunits in a load-bearing, compression-resistant frame structure characterize this approach. An open, macro- and microporous internal architecture (100 µm-2 mm pores) optimizes conditions for oxygen and nutrient supply to the implant's inner areas by diffusion. A prototype was 3D-printed applying Fused Filament Fabrication using PLA. After incubation with Saos-2 (Sarcoma osteogenic) cells for 14 days, cell morphology, cell distribution, cell survival (fluorescence microscopy and LDH-based cytotoxicity assay), metabolic activity (MTT test), and osteogenic gene expression were determined. The adherent cells showed colonization properties, proliferation potential, and osteogenic differentiation. The innovative design, with its porous structure, is a promising matrix for cell settlement and proliferation. The modular design allows easy upscaling and offers a solution for LBDT.