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

The Role of Leukocyte-Platelet-Rich Fibrin in Promoting Wound Healing in Diabetic Foot Ulcers

To explore the effect of leukocyte-platelet-rich fibrin (L-PRF) on promoting wound healing in diabetic foot ulcers. A total of 42 patients with diabetic foot ulcers at our hospital from January 2017 to July 2020 were retrospectively analyzed. A control group and a PRF group were established. The two groups of patients underwent debridement. In the platelet-rich fibrin (PRF) group, autologous L-PRF was used to cover ulcer wounds. One time each week, Vaseline gauze was used to cover the ulcer wounds. In contrast, the control group was treated with the external application of mupirocin ointment and recombinant human epidermal growth factor gel (yeast). Two times each week, the sterile Vaseline gauze was covered with a bandage. Both groups were treated for 5 weeks. The wound recovery of the two groups was observed. During the early stage of treatment (first and second weeks) for diabetic foot ulcers, the wound healing rate was significantly better with L-PRF treatment than traditional treatment. For later-stage treatment (third to fifth weeks), the overall cure rate was higher with L-PRF than the traditional treatment method. L-PRF can effectively promote wound healing in diabetic foot ulcers.

Using platelet-rich fibrin scaffolds with diced cartilage graft in the treatment of empty nose syndrome

Empty nose syndrome (ENS) is a rare entity in patients who undergo sinonasal surgery due to over-resection of the turbinate. This syndrome leads to debilitating symptoms that include dry nose, painful nasal breathing, paradoxical nasal obstruction, crusting, and sleep disorder. The goal of surgical treatment is to reestablish the volume of the turbinates to rehabilitate the nasal resistance. Endonasal microplasty with cartilage implants on the lateral wall of the nasal cavity is useful for creating the neoturbinate. Here, we present 2 cases that describe the management of empty nose syndrome by endonasal microplasty using platelet-rich fibrin (PRF) scaffolds embedded with a diced cartilage graft. The integration of the PRF scaffolds with diced cartilage efficiently facilitated the reestablishment of the neoturbinate. This autologous biomaterial is suitable for the treatment of ENS.

Multifunctional hydrogel/platelet-rich fibrin/nanofibers scaffolds with cell barrier and osteogenesis for guided tissue regeneration/guided bone regeneration applications

Periodontal defect seriously affects people's life health and quality. Guided tissue regeneration (GTR) and guided bone regeneration (GBR) have made great progress in periodontal disease treatment, but some deficiencies existed in commercial materials of GTR and GBR. For obtaining better therapeutic effects, multifunctional composite scaffolds containing different biological macromolecules were developed in this study. Chitosan/poly (γ-glutamic acid)/nano-hydroxyapatite hydrogels (CP/nHA) made by electrostatic interactions and lyophilization were filled in the bone defects to achieve osteogenesis. Platelet-rich fibrin (PRF) extracted from blood could accelerate bone formation by releasing various bioactive substances as middle layer of composite scaffolds. Polycaprolactone/gelatin nanofibers (PG) prepared by electrospinning were attached to the junction of soft and hard tissue, which could prevent fibrous tissue from infiltrating into bone defects. The composite scaffolds showed good morphology, biocompatibility, cell barriers and osteogenic differentiation in vitro. The excellent ability of bone formation was verified by implantation of triple-layered composite scaffolds into alveolar bone defects in rabbit in vivo. The hierarchical structure was conducive to personalized customization to meet the needs of different defects. All in all, the multifunctional scaffolds could play important roles of GTR and GBR in alveolar bone regeneration and provide good application prospect for bone repair in clinic.

In Vitro Antimicrobial Properties and Their Mechanisms in Relation to Reactive Oxygen Species of Canine Platelet-Rich Fibrin

Platelet-rich fibrin (PRF), which has been shown to promote wound and bone regeneration, has demonstrated antimicrobial properties against periodontal pathogens. However, in veterinary medicine, no study has determined the antimicrobial effects of canine platelet-rich fibrin (cPRF). Therefore, this study aimed to determine the antimicrobial effect of cPRF against E. coli and S. pseudintermedius found in dogs' wounds and against the standard strain S. aureus. Additionally, the mechanism of the existing antibacterial activity of cPRF, which involves the formation of reactive oxygen species (ROS), was tested. Blood samples from six dogs were processed for cPRF. The antimicrobial properties of three groups (growth control, cPRF, and drug control) were evaluated at 0.5, 4, 8, and 24 h using a time-kill assay. The killing mechanisms involving ROS were evaluated using horseradish peroxidase (HRP) to suppress ROS production in PRF (PRF-SR). Subsequently, tests for antimicrobial properties and ROS generation were compared to those of the growth control and cPRF groups. The results showed that cPRF had significant antimicrobial properties against E. coli but no antimicrobial properties against S. pseudintermedius. After the ROS suppression, PRF-SR did not show an antimicrobial property against E. coli. Moreover, cPRF-treated bacteria exhibited significantly greater intracellular ROS than PRF-SR. In conclusion, canine PRF showed an antimicrobial effect against E. coli, and its antibacterial mechanism was related to releasing ROS.

Platelet-rich plasma for pilonidal disease: a systematic review

OBJECTIVE

To examine the use of platelet-rich plasma (PRP) for treatment of pilonidal disease (PD) and thus provide a reference for clinical application.

METHODS

A systematic review of PubMed and the Cochrane Library was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We considered all studies that reported the use of PRP for treatment of PD. Extracted data included the first author's name, year of publication, study type, number of included patients, inclusion and exclusion criteria, interventions, anesthesia, application of PRP (source, preparation, dose, and operation), antibiotics, follow-up time, therapeutic outcomes, and adverse events.

RESULTS

In total, eight randomized controlled trials and one prospective cohort study involving 809 patients were included. PRP reduced pain, accelerated healing, and reduced adverse events. The application of combined minimally invasive surgery achieved better results. However, overfilling of the wound with PRP in minimally invasive surgeries was shown to potentially increase the risk of adverse events.

CONCLUSION

PRP can be used as an adjuvant treatment in PD surgery to improve the therapeutic effect and reduce adverse events. The optimal combination of PRP and various factors is an important direction of future research.INPLASY registration number: INPLASY2023100070.

Reinforcement of colon anastomosis healing with leukocyte platelet-rich fibrin in rabbit model

AIM

This study investigated the regenerative efficacy of leukocyte platelet-rich fibrin (L-PRF) on colon anastomotic healing in rabbits.

MAIN METHODS

Thirty-six healthy male white New Zealand rabbits were subjected to complete transactions of the ascending colon. The rabbits were equally divided into two groups: the control group, where the transected colon ends were anastomosed by a simple interrupted suture pattern, and the L-PRF-treated group, in which L-PRF was wrapped entirely around the anastomotic line. The postoperative acute pain scale was assessed using the Bristol Rabbit Pain Scale before surgery and at each four-hour interval post-operatively. After euthanizing the rabbits, the adhesion degree score, anastomotic bursting pressure, and stenosis degree of the anastomotic colon were assessed, and histopathological examination at the 7th, 14th, and 28th days postoperatively.

KEY FINDINGS

Rabbits in both groups showed a significant increase in pain scores compared to baseline. Postoperatively, the L-PRF group exhibited significantly lower pain scores, adhesion scores, and stenosis degrees than the control group. However, the anastomotic bursting pressure was significantly higher in the L-PRF group. Re-epithelialization, polymorphonuclear neutrophil infiltration, granulation tissue formation, and collagen deposition scores were improved considerably in the L-PRF group compared to the control group. Immunostaining of growth factor expression was significantly lower in the control than in the L-PRF group.

SIGNIFICANCE

The L-PRF can augment collagen deposition, re-epithelialize the mucosa, promote angiogenesis, reduce adhesions, and diminish the stenosis degree scores. Therefore, it can be considered a promising aid in healing bowel anastomoses.

Hypoxia Preconditioned Serum (HPS) Promotes Proliferation and Chondrogenic Phenotype of Chondrocytes In Vitro

Autologous chondrocyte implantation (ACI) for the treatment of articular cartilage defects remains challenging in terms of maintaining chondrogenic phenotype during in vitro chondrocyte expansion. Growth factor supplementation has been found supportive in improving ACI outcomes by promoting chondrocyte redifferentiation. Here, we analysed the chondrogenic growth factor concentrations in the human blood-derived secretome of Hypoxia Preconditioned Serum (HPS) and assessed the effect of HPS-10% and HPS-40% on human articular chondrocytes from osteoarthritic cartilage at different time points compared to normal fresh serum (NS-10% and NS-40%) and FCS-10% culture conditions. In HPS, the concentrations of TGF-beta1, IGF-1, bFGF, PDGF-BB and G-CSF were found to be higher than in NS. Chondrocyte proliferation was promoted with higher doses of HPS (HPS-40% vs. HPS-10%) and longer stimulation (4 vs. 2 days) compared to FCS-10%. On day 4, immunostaining of the HPS-10%-treated chondrocytes showed increased levels of collagen type II compared to the other conditions. The promotion of the chondrogenic phenotype was validated with quantitative real-time PCR for the expression of collagen type II (COL2A1), collagen type I (COL1A1), SOX9 and matrix metalloproteinase 13 (MMP13). We demonstrated the highest differentiation index (COL2A1/COL1A1) in HPS-10%-treated chondrocytes on day 4. In parallel, the expression of differentiation marker SOX9 was elevated on day 4, with HPS-10% higher than NS-10/40% and FCS-10%. The expression of the cartilage remodelling marker MMP13 was comparable across all culture conditions. These findings implicate the potential of HPS-10% to improve conventional FCS-based ACI culture protocols by promoting the proliferation and chondrogenic phenotype of chondrocytes during in vitro expansion.

Osteochondral Regeneration Ability of Uncultured Bone Marrow Mononuclear Cells and Platelet-Rich Fibrin Scaffold

OBJECTIVES

Platelet-rich fibrin (PRF) and bone marrow mononuclear cells are potential scaffolds and cell sources for osteochondral regeneration. The main aim of this paper is to examine the effects of PRF scaffolds and autologous uncultured bone marrow mononuclear cells on osteochondral regeneration in rabbit knees.

MATERIALS AND METHODS

Three different types of PRF scaffolds were generated from peripheral blood (Ch-PRF and L-PRF) and bone marrow combined with uncultured bone marrow mononuclear cells (BMM-PRF). The histological characteristics of these scaffolds were assessed via hematoxylin-eosin staining, PicroSirius red staining, and immunohistochemical staining. Osteochondral defects with a diameter of 3 mm and depth of 3 mm were created on the trochlear groove of the rabbit's femur. Different PRF scaffolds were then applied to treat the defects. A group of rabbits with induced osteochondral defects that were not treated with any scaffold was used as a control. Osteochondral tissue regeneration was assessed after 2, 4, and 6 weeks by macroscopy (using the Internal Cartilage Repair Society score, X-ray) and microscopy (hematoxylin-eosin stain, safranin O stain, toluidine stain, and Wakitani histological scale, immunohistochemistry), in addition to gene expression analysis of osteochondral markers.

RESULTS

Ch-PRF had a heterogeneous fibrin network structure and cellular population; L-PRF and BMM-PRF had a homogeneous structure with a uniform distribution of the fibrin network. Ch-PRF and L-PRF contained a population of CD45-positive leukocytes embedded in the fibrin network, while mononuclear cells in the BMM-PRF scaffold were positive for the pluripotent stem cell-specific antibody Oct-4. In comparison to the untreated group, the rabbits that were given the autologous graft displayed significantly improved healing of the articular cartilage tissue and of the subchondral bone. Regeneration was gradually observed after 2, 4, and 6 weeks of PRF scaffold treatment, which was particularly evident in the BMM-PRF group.

CONCLUSIONS

The combination of biomaterials with autologous platelet-rich fibrin and uncultured bone marrow mononuclear cells promoted osteochondral regeneration in a rabbit model more than platelet-rich fibrin material alone. Our results indicate that autologous platelet-rich fibrin scaffolds combined with uncultured bone marrow mononuclear cells applied in healing osteochondral lesions may represent a suitable treatment in addition to stem cell and biomaterial therapy.

Fibrin and Marine-Derived Agaroses for the Generation of Human Bioartificial Tissues: An Ex Vivo and In Vivo Study

Development of an ideal biomaterial for clinical use is one of the main objectives of current research in tissue engineering. Marine-origin polysaccharides, in particular agaroses, have been widely explored as scaffolds for tissue engineering. We previously developed a biomaterial based on a combination of agarose with fibrin, that was successfully translated to clinical practice. However, in search of novel biomaterials with improved physical and biological properties, we have now generated new fibrin-agarose (FA) biomaterials using 5 different types of agaroses at 4 different concentrations. First, we evaluated the cytotoxic effects and the biomechanical properties of these biomaterials. Then, each bioartificial tissue was grafted in vivo and histological, histochemical and immunohistochemical analyses were performed after 30 days. Ex vivo evaluation showed high biocompatibility and differences in their biomechanical properties. In vivo, FA tissues were biocompatible at the systemic and local levels, and histological analyses showed that biointegration was associated to a pro-regenerative process with M2-type CD206-positive macrophages. These results confirm the biocompatibility of FA biomaterials and support their clinical use for the generation of human tissues by tissue engineering, with the possibility of selecting specific agarose types and concentrations for applications requiring precise biomechanical properties and in vivo reabsorption times.

Silver nanoparticles and platelet-rich fibrin accelerate tendon healing in donkey

This study investigated the effect of the silver nanoparticles (AgNPs) and platelet-rich fibrin (PRF) in the healing of the severed superficial digital flexor tendon in donkeys (SDFT). Twenty-seven adult donkeys were used in the study. The animals were divided into three equal groups. The first group (control group) in which the severed SDFT was sutured without the addition of any adjuvant. In the second group, there was a suture of severed SDFT with the addition of 1 ml of 1 mM silver nanoparticles (AgNPs group). The third group was subjected to the cutting of SDFT and then the addition of PRF after its suture. Each group of animals was divided into three equal subgroups that were examined after 1, 2, and 3 months. Each group of animals was clinically evaluated by assessing lameness. Gross and microscopic examinations of the healed tendons were performed after 1, 2, and 3 months of surgery. In comparison to the control group, the lameness degree decreased in the PRF and AgNPs groups, particularly in the third month after surgery. Furthermore, the lameness decreased significantly after the 3rd month relative to the 1st-month lameness in the AgNPs group. Interestingly, it was found that the PRF and AgNPs enhanced cell alignment and collagen deposition at the site of tendon injury, particularly among third-month subgroups. Therefore, it could be concluded that the PRF and AgNPs are effective materials for enhancing SDFT healing in donkeys.

Double membrane platelet-rich fibrin (PRF) - Synovium succeeds in regenerating cartilage defect at the knee: An experimental study on rabbit

Background

This study aims to prove the healing results (regeneration) in cartilage defects using a combination treatment of microfractures and transplantation synovium-platelet rich fibrin (S-PRF).

Methods

A cartilage defect was made in the trochlear groove of the knee of adult New Zealand white rabbits, and was classified into three treatment groups. The group 1 was cartilage defect without treatment, 2 with microfracture treatment, and 3 with microfracture covered with a synovium-platelet rich fibrin (S-PRF) membrane. Twelve weeks after the intervention, the animals were macroscopically and histologically examined, and evaluated by the International Cartilage Repair Society (ICRS). Additionally, the expression of aggrecan and type 2 collagen was examined by real-time-PCR.

Results

The ICSR scores for macroscopic were significantly higher in the microfracture and S-PRF transplant group than in the other groups. Also, the ICSR scores for histology were significantly higher in this group. The expression of aggrecan and type 2 collagen was higher in the group that received complete treatment.

Conclusions

Microfractures and transplantation of synovium-platelet rich fibrin (S-PRF) can regenerate knee cartilage defects which have been shown to increase the expression of mRNA aggrecan and mRNA type 2 collagen resulting in excellent repair.

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.

Preclinical and clinical orthotopic transplantation of decellularized/engineered tracheal scaffolds: A systematic literature review

Severe tracheal injuries that cannot be managed by mobilization and end-to-end anastomosis represent an unmet clinical need and an urgent challenge to face in surgical practice; within this scenario, decellularized scaffolds (eventually bioengineered) are currently a tempting option among tissue engineered substitutes. The success of a decellularized trachea is expression of a balanced approach in cells removal while preserving the extracellular matrix (ECM) architecture/mechanical properties. Revising the literature, many Authors report about different methods for acellular tracheal ECMs development; however, only few of them verified the devices effectiveness by an orthotopic implant in animal models of disease. To support translational medicine in this field, here we provide a systematic review on studies recurring to decellularized/bioengineered tracheas implantation. After describing the specific methodological aspects, orthotopic implant results are verified. Furtherly, the only three clinical cases of compassionate use of tissue engineered tracheas are reported with a focus on outcomes.

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.

The effect of the silver nanoparticles and platelet-rich fibrin in the healing of the severed superficial digital flexor tendon in donkeys (Equus asinus).. [DOI: 10.21203/rs.3.rs-2075827/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

This study investigated the effect of the silver nanoparticles (AgNPs) and platelet-rich fibrin (PRF) in the healing of the severed superficial digital flexor tendon in donkeys (SDFT). Twenty-seven adult donkeys were used in the study. The animals were divided into three equal groups. The 1st group (control group) in which the severed SDFT was sutured without the addition of any adjuvant. In the 2nd group, there was a suture of severed SDFT with the addition of 1ml of 1mM silver nanoparticles (AgNPs group). The 3rd group was subjected to the cutting of SDFT and then the addition of PRF after its suture. Each group of animals was divided into three equal subgroups that were examined after one, two, and three months, respectively. Each group of animals was clinically evaluated by assessing lameness. Gross and microscopic examinations of the healed tendons were performed after 1, 2, and 3 months of surgery. The results revealed that the lameness degree decreased in the PRF and AgNPs groups, in comparison to the control group, especially in the third month after surgery. As well as the lameness decreased significantly after the 3rd month relative to the 1st-month lameness in the AgNPs group. Interestingly, it was found that the PRF and AgNPs enhanced cell alignment and collagen deposition at the site of tendon injury, particularly among third-month subgroups. Therefore, it could be concluded that the PRF and AgNPs are effective materials for enhancing SDFT healing in donkeys.

Treatment of bone defects with bovine hydroxyapatite xenograft and platelet rich fibrin (PRF) to accelerate bone healing

INTRODUCTION

The autograft treatment has become a gold standard therapy for bone defects, although it has its drawbacks and a side effect of donor site morbidity. Furthermore, the bovine hydroxyapatite xenograft due to its excellent osteoconduction characteristic combined with platelet-rich fibrin (PRF), which is a source of growth factor, makes both utilized as therapeutic measures. Therefore, this study examines the potential use of bovine hydroxyapatite xenograft and platelet-rich fibrin in the treatment of bone defects.

METHOD

The report on three cases of bone defects that were treated using a combination of bovine hydroxyapatite xenograft and platelet-rich fibrin (PRF) for internal fixation and grafting was used for this investigation. The study showed that delayed and non-union fractures of the femur, humerus, and tibia may cause bone deformities.

RESULT

The outcome revealed a positive clinical and radiological finding about using the combination of bovine hydroxyapatite xenograft and platelet-rich fibrin (PRF) in the repair of bone defects and acceleration of healing processes.

CONCLUSION

The use of a combination of bovine hydroxyapatite xenograft and platelet-rich fibrin (PRF) in the repair of bone defects shows more effective and accelerated healing. Future studies with a bigger sample size may be carried out and are expected to yield optimal results.

Progress of Platelet Derivatives for Cartilage Tissue Engineering

Articular cartilage has limited self-regeneration ability for lacking of blood vessels, nerves, and lymph that makes it a great challenge to repair defects of the tissue and restore motor functions of the injured or aging population. Platelet derivatives, such as platelet-rich plasma, have been proved effective, safe, and economical in musculoskeletal diseases for their autologous origin and rich in growth factors. The combination of platelet derivatives with biomaterials provides both mechanical support and localized sustained release of bioactive molecules in cartilage tissue engineering and low-cost efficient approaches of potential treatment. In this review, we first provide an overview of platelet derivatives and their application in clinical and experimental therapies, and then we further discuss the techniques of the addition of platelet derivatives and their influences on scaffold properties. Advances in cartilage tissue engineering with platelet derivatives as signal factors and structural components are also introduced before prospects and concerns in this research field. In short, platelet derivatives have broad application prospects as an economical and effective enhancement for tissue engineering–based articular cartilage repair.

Osteochondral regeneration in rabbit using xenograft decellularized ECM in combination with different biological products; platelet-rich fibrin, amniotic membrane extract, and mesenchymal stromal cells

This study aimed to investigate the regenerative effect of decellularized osteochondral ECM xenograft in combination with various biological products in an osteochondral (OC) defect. OC tissue from the sheep femur were obtained and decellularized. The decellularized ECM (dECM) was combined with either platelet-rich fibrin (PRF), amniotic membrane extract (AME), or rabbit bone marrow-derived mesenchymal stromal cells (rBMSCs). The hybrid dECM-biological products were then utilized for the treatment of rabbit OC critical size defects. The regenerative potential of different groups was compared using; MRI, macroscopic assessment, histopathology, and histomorphometry. All characterizations analysis verified successful decellularization. Three months post-surgery, macroscopic findings indicated that dECM was better compared to controls. Also, dECM in combination with AME, PRF, and rBMSCs showed enhanced OC regeneration compared to only dECM (AME: +100%, PRF: +61%, rBMSCs: +28%). In particular, the dECM+AME group results in the best integration of new cartilage into surrounding cartilage tissue. The histomorphometric evaluations demonstrated enhancement in new cartilage formation and bone tissue (86.5 ± 5.9% and 90 ± 7.7%, respectively) for the dECM+AME group compared to other groups. Furthermore, histological results for the dECM+AME elucidated a mature hyaline cartilage tissue that covered the new and symmetrically formed subchondral bone, exhibiting a significantly higher regenerative effect compared to all other treated groups. This finding was also confirmed with MRI images. The current study revealed that in addition to the benefits of dECM alone, its combination with AME indicated to have a superior regenerative effect on OC regeneration. Overall, dECM+AME may be considered a suitable construct for treating knee OC injuries.

Autologous Platelet-Rich Fibrin Membrane to Augment Healing of Microfracture Has Better Macroscopic and Histologic Grades Compared With Microfracture Alone on Chondral Defects in a Rabbit Model

PURPOSE

To determine the in vivo effectiveness of a single-stage surgical procedure that combines microfracture and an autologous platelet-rich fibrin (PRF) membrane for cartilage repair in a rabbit model.

METHODS

Cartilage defects were created in the trochlear groove of the knees of adult white rabbits. Defects were divided into 2 treatment groups: microfracture only (control group) and microfracture covered by a PRF membrane (PRF group). To evaluate the repair cartilage, assessments were performed at 4, 12, and 24 weeks postoperatively using the International Cartilage Repair Society (ICRS) macroscopic scoring system and modified Wakitani histologic grading system.

RESULTS

The mean ICRS macroscopic scores in the control and PRF groups were 4.1 and 5.8, respectively, at 4 weeks (P = .0623); 6.3 and 9.8, respectively, at 12 weeks (P = .006); and 6.5 and 10.3, respectively, at 24 weeks (P = .010). The mean modified Wakitani scores in the control and PRF groups were 4.0 and 3.9, respectively, at 4 weeks (P > .999); 5.3 and 10.4, respectively, at 12 weeks (P = .006); and 2.6 and 7.4, respectively, at 24 weeks (P = .012).

CONCLUSIONS

The ICRS macroscopic scores and modified Wakitani scores showed that a single-stage surgical procedure combining microfracture and a PRF membrane was more effective than surgery with only microfracture for promoting cartilage repair.

CLINICAL RELEVANCE

A single-stage surgical procedure combining microfracture and an autologous PRF membrane is a potentially beneficial treatment method for cartilage defects that does not require using any xenocollagen membrane.

Adipose Stem Cells in Regenerative Medicine: Looking Forward

Over the last decade, stem cell-based regenerative medicine has progressed to clinical testing and therapeutic applications. The applications range from infusions of autologous and allogeneic stem cells to stem cell-derived products. Adult stem cells from adipose tissue (ASCs) show significant promise in treating autoimmune and neurodegenerative diseases, vascular and metabolic diseases, bone and cartilage regeneration and wound defects. The regenerative capabilities of ASCs in vivo are primarily orchestrated by their secretome of paracrine factors and cell-matrix interactions. More recent developments are focused on creating more complex structures such as 3D organoids, tissue elements and eventually fully functional tissues and organs to replace or repair diseased or damaged tissues. The current and future applications for ASCs in regenerative medicine are discussed here.

Endogenous repair theory enriches construction strategies for orthopaedic biomaterials: a narrative review

The development of tissue engineering has led to new strategies for mitigating clinical problems; however, the design of the tissue engineering materials remains a challenge. The limited sources and inadequate function, potential risk of microbial or pathogen contamination, and high cost of cell expansion impair the efficacy and limit the application of exogenous cells in tissue engineering. However, endogenous cells in native tissues have been reported to be capable of spontaneous repair of the damaged tissue. These cells exhibit remarkable plasticity, and thus can differentiate or be reprogrammed to alter their phenotype and function after stimulation. After a comprehensive review, we found that the plasticity of these cells plays a major role in establishing the cell source in the mechanism involved in tissue regeneration. Tissue engineering materials that focus on assisting and promoting the natural self-repair function of endogenous cells may break through the limitations of exogenous seed cells and further expand the applications of tissue engineering materials in tissue repair. This review discusses the effects of endogenous cells, especially stem cells, on injured tissue repairing, and highlights the potential utilisation of endogenous repair in orthopaedic biomaterial constructions for bone, cartilage, and intervertebral disc regeneration.

Culture and Differentiation of Human Umbilical Cord-Derived Mesenchymal Stem Cells on Growth Factor-Rich Fibrin Scaffolds to Produce Engineered Cartilages

INTRODUCTION

After injuries, the cartilage healing capacity is limited owing to its nature as a particular connective tissue without blood vessels, lymphatics, or nerves. The creation of artificial cartilage tissue mimics the biological properties of native cartilage and can reduce the need for donated tissue. Fibrin is a type of biodegradable scaffold that has great potential in tissue engineering applications. It can become good material for cell adhesion and proliferation in vitro. Therefore, this study aimed to create a cartilage tissue in vitro using umbilical cord-derived mesenchymal stem cells (UCMSC) and growth factor-rich fibrin (GRF) scaffolds.

METHODS

UCMSCs were isolated and expanded, and platelet-rich plasma (PRP) preparations were performed following previously published protocols. PRP was activated (aPRP) by a 0.45-μm syringe filter to release growth factors inside the platelets. Each 2.105 of the UCMSCs were suspended in 2 ml of aPRP to make the mixture of MSC and PRP (MSC-PRP). Then, Ca2+ solution was added to this mixture to produce the fibril scaffold with UCMSCs inside. UCMSCs' adhesion and proliferation inside the scaffold were evaluated by observation under inverted microscopy, H-E staining, MTT assays, and scanning electron microscopy (SEM). The fibril structure containing UCMSCs was cultured, and chondrogenesis was induced using commercial chondrogenesis media for 21 days (iMSC-GRF). The differentiation in efficacy toward cartilage was evaluated based on the accumulation of aggrecan (acan), glycosaminoglycans (GAGs), and collagen type II (Col II).

RESULTS

The results showed that we successfully created a cartilage tissue with some characteristics that mimic the properties of natural cartilage. The engineered cartilage tissue was positive with some cartilage protein, such as acan, GAG, and Coll II. In vitro cartilage presented some natural chondrocyte-like cells. The artificial cartilage tissue was positive for CD14, CD34, CD90, CD105, and HLA-DR and negative for CD44, CD45, and CD73.

CONCLUSION

These results showed that using UCMSCs and growth factor-rich fibril from platelet-rich plasma was feasible to produce engineered cartilage tissue for further experiments or clinical usage.

Extracellular Matrix Scaffold Using Decellularized Cartilage for Hyaline Cartilage Regeneration

The repair of osteochondral defects is among the top ten medical needs of humans in the 21st centuries with many countries facing rapidly aging population involved with osteoarthritis as a major contributor to global disease burden. Tissue engineering methods have offered new windows of hope to treat such disorders and disabilities. Regenerative approaches to cartilage injuries require careful replication of the complex microenvironment of the native tissue. The decellularized hyaline cartilage derived from human allografts or xenografts is potentially an ideal scaffold, simulating the mechanical and biochemical properties, as well as biological microarchitecture of the hyaline cartilage. There have been many attempts to regenerate clinically viable hyaline cartilage tissue using decellularized cartilage-derived extracellular matrix with stem cell technology. This chapter describes the reproducible methods for hyaline cartilage decellularization and recellularization. In addition, quality control and characterization requirements of the product at each step, as well as the clinical applications of final product have been discussed.

Supercritical carbon dioxide decellularized porcine cartilage graft with PRP attenuated OA progression and regenerated articular cartilage in ACLT-induced OA rats

Knee osteoarthritis (OA) is a common degenerative articular disorder and considered one of the primary causes of pain and functional disability. Knee OA is prevalent in 10% of men and 13% of women aged 60 years above. The study aims to use cartilage tissue engineering that combines the triads of decellularized porcine cartilage graft as "scaffold," plasma rich platelet (PRP) as "signal" and chondrocytes from rat as "cell" to attenuate ACLT-induced OA progression and regenerate the knee cartilage in rats. Decellularization of the porcine cartilage was characterized by hematoxylin and eosin, 4,6-Diamidino-2-phenylindole staining, scanning electron microscopy and residual DNA quantification. The protective effect of decellularized porcine cartilage graft (dPCG) was evaluated by intra-articular administration in surgically induced anterior cruciate ligament transection (ACLT) rat osteoarthritis (OA) model. Supercritical carbon dioxide technology completely decellularized the porcine cartilage. Intra-articular administration of dPCG with or without PRP significantly reduced the ACLT-induced OA symptoms and attenuated the OA progression. Pain-relief by dPCG with or without PRP was assessed by capacitance meter and improved articular cartilage damage in the rat knee was characterized by X-ray and micro-CT. Besides, the histological analysis depicted cartilage protection by dPCG with or without PRP. The repairation and attenuation effect by dPCG with or without PRP in the articular knee cartilage damage were also explored by safranin-O, type II collagen, aggrecan and SOX-9 immuno-staining. To conclude, intra-articular administration of dPCG with or without PRP is efficient in repairing the damaged cartilage in the experimental OA model.

Regenerative Potential of Platelet-Rich Fibrin Releasate Combined with Adipose Tissue-Derived Stem Cells in a Rat Sciatic Nerve Injury Model

Sciatic nerve injuries, not uncommon in trauma with a limited degree of functional recovery, are considered a persistent clinical, social, and economic problem worldwide. Accumulating evidence suggests that stem cells can promote the tissue regeneration through various mechanisms. The aim of the present study was to investigate the role of adipose tissue–derived stem cells (ADSCs) and combine with platelet-rich fibrin releasate (PRFr) in the regeneration of sciatic nerve injury in rats. Twenty-four Sprague-Dawley rats were randomly assigned to four groups, a blade was used to transect the left hindlimb sciatic nerve, and silicon tubes containing one of the following (by injection) were used to bridge the nerve proximal and distal ends (10-mm gap): group 1: untreated controls; group 2: PRFr alone; group 3: ADSCs alone; group 4: PRFr + ADSCs-treated. Walking function was assessed in horizontal rung ladder apparatus to compare the demands of the tasks and test sensitivity at 1-mo interval for a total of 3 mo. The gross inspection and histological examination was performed at 3 mo post transplantation. Overall, PRFr + ADSCs-treated performed better compared with PRFr or ADSCs injections alone. Significant group differences of neurological function were observed in ladder rung walking tests in all treated groups compared to that of untreated controls (P < 0.05). This injection approach may provide a successfully employed technique to target sciatic nerve defects in vivo, and the combined strategy of ADSCs with PRFr appears to have a superior effect on nerve repair.

Cues from human atrial extracellular matrix enrich the atrial differentiation of human induced pluripotent stem cell-derived cardiomyocytes

New robust and reproducible differentiation approaches are needed to generate induced pluripotent stem cell (iPSC)-derived cardiomyocytes of specific subtypes in predictable quantities for tissue-specific disease modeling, tissue engineering, and eventual clinical translation. Here, we assessed whether powdered decellularized extracellular matrix (dECM) particles contained chamber-specific cues that could direct the cardiac differentiation of human iPSCs toward an atrial phenotype. Human hearts were dissected and the left ventricle (LV) and left atria (LA) were isolated, minced, and decellularized using an adapted submersion decellularization technique to generate chamber-specific powdered dECM. Comparative proteomic analyses showed chamber-specific dECM segregation, with atrial- and ventricle-specific proteins uniquely present in powdered dECM-hA and dECM-hV, respectively. Cell populations differentiated in the presence of dECM-hA showed upregulated atrial molecular markers and a two-fold increase in the number of atrial-like cells as compared with cells differentiated with dECM-hV or no dECM (control). Finally, electrophysiological data showed an increase in action potentials characteristic of atrial-like cells in the dECM-hA group. These findings support the hypothesis that dECM powder derived from human atria retained endogenous cues to drive cardiac differentiation toward an atrial fate.

Application of Concentrated Growth Factors Membrane for Human Umbilical Cord Wharton’s Jelly Mesenchymal Stem Cell Differentiation towards Keratinocytes

Concentrated growth factors are extracted from platelet-rich plasma obtained from healthy adult veins by physical gradient centrifugation, and the activated platelets release various growth factors and cytokines, which can be further converted into concentrated growth factors liquid or gel preparations by different centrifuge tubes. These preparations are widely used in clinical treatments in various fields, such as dentistry, dermatology and surgery. In this article, concentrated growth factors gel and platelet-poor plasma gel obtained from six healthy adults were pressed into a concentrated growth factors membrane and platelet-poor plasma membrane. We examined whether the 3D fibrin mesh and the various concentrated growth factors within the concentrated growth factors membrane could be used as a bioscaffold for the human Wharton’s jelly umbilical cord stem cell line or the HaCaT cell line to attach, proliferate and form epidermal-like tissue. We also aimed to implant umbilical cord stem cells on the concentrated growth factors membrane or platelet-poor plasma membrane, and further compare the characteristics of similar tissues after 4 weeks in in vitro culture. The results showed that human Wharton’s jelly umbilical cord mesenchymal stem cells, implanted on the upper surface of the concentrated growth factors membrane, showed subsequent cell attachment and proliferation. After 4 weeks of ex vivo tissue culture, a multi-layer epidermal-like tissue formed on the upper surface of the membrane containing concentrated growth factors. This tissue had a minimum thickness of 89.91 µm to a maximum of 204.19 µm, mean ± SD = 144.36 µm ± 43.14 µm. Sections of these multi-layer epidermal-like tissues were used for immunohistochemical staining. We found that 79.8% ± 7.2% of the cells expressed the pancytokeratin marker, 29.5% ± 9.4% of the cells expressed the P63 marker, and 71.7% ± 3.9% of the cells expressed the vimentin marker. After the same 4 weeks in the in vitro culture, the HaCaT cells could attach to the concentrated growth factors membrane and proliferate to form a multi-layer tissue, The tissue had a minimum thickness of 63.17 µm to a maximum of 100.26 µm, mean ± SD = 74.05 µm ± 13.44 µm. We found that 88.1% ± 4.9% of the cells expressed the pancytokeratin marker, 63.6% ± 11.4% of the cells expressed the P63 marker, and 79% ± 9.9% of the cells expressed the vimentin marker. Also, after 4 weeks in the in vitro culture, it showed that umbilical cord stem cells could attach to the platelet-poor plasma membrane, proliferate and distribute in the whole-tissue sections. We found that 9.7% ± 2.4% of the cells expressed the pancytokeratin marker, 7.45% ± 1.9% of the cells expressed the P63 maker, and 95.9% ± 3.7% of the cells expressed the vimentin marker. In terms of the percentage of umbilical cord stem cells expressing pancytokeratin, P63, or vimentin cell markers, there was a significant difference between cultivating in the concentrated growth factors membrane scaffold and the platelet-poor plasma membrane scaffolds. In terms of the percentage of umbilical cord stem cells or HaCaT cells (cultivating in the concentrated growth factors membrane) expressing pancytokeratin, P63, or vimentin cell markers, there was no significant difference. These results suggested that umbilical cord Wharton’s jelly mesenchymal stem cells can use the concentrated growth factors membrane (composed of 3D fibrin mesh, and various growth factors and cytokines) as an effective and self-contained bioscaffold to differentiate towards keratinocytes-like cells. In the future, donors’ own concentrated growth factors membrane can be applied as an auxiliary tool for autologous tissue regeneration.

Large-Pore Platelet-Rich Fibrin with a Mg Ring to Allow MC3T3-E1 Preosteoblast Migration and to Improve Osteogenic Ability for Bone Defect Repair

Platelet-rich fibrin (PRF) is a natural fibrin meshwork material with multiple functions that are suitable for tissue engineering applications. PRF provides a suitable scaffold for critical-size bone defect treatment due to its platelet cytokines and rich growth factors. However, the structure of PRF not only promotes cell attachment but also, due to its density, provides a pool for cell migration into the PRF to facilitate regeneration. In our study, we used repeated freeze drying to enlarge the pores of PRF to engineer large-pore PRF (LPPRF), a type of PRF that has expanded pores for cell migration. Moreover, a biodegradable Mg ring was used to provide stability to bone defects and the release of Mg ions during degradation may enhance osteoconduction and osteoinduction. Our results revealed that cell migration was more extensive when LPPRF was used rather than when PRF was used and that LPPRF retained the growth factors present in PRF. Moreover, the Mg ions released from the Mg ring during degradation significantly enhanced the calcium deposition of MC3T3-E1 preosteoblasts. In the present study, a bone substitute comprising LPPRF combined with a Mg ring was demonstrated to have much potential for critical-size bone defect repair.

Platelet-rich fibrin: Basics of biological actions and protocol modifications

Platelet-rich fibrin (PRF) represents second generation of platelet concentrates, which has gained increasing awareness in recent years for regenerative procedures. This biologic additive is completely autologous, easy to prepare, has minimal expense, and possesses prolonged growth factor release, together with several other advantages over traditionally prepared platelet concentrates. Since its introduction, various protocols for PRF preparation have been proposed with different amounts of growth factors and other biomolecules necessary for wound healing. However, reference data about potential effect of some PRF components on hard and soft tissue healing are still conflicting. The current article intends to clarify the relevant advances about physiological role of certain PRF components and to provide insight into the new developmental approach. Also, this review summarizes the evolution of platelet concentrates and biologic properties of different modifications of PRF procedure.

Applications of Biocompatible Scaffold Materials in Stem Cell-Based Cartilage Tissue Engineering

Cartilage, especially articular cartilage, is a unique connective tissue consisting of chondrocytes and cartilage matrix that covers the surface of joints. It plays a critical role in maintaining joint durability and mobility by providing nearly frictionless articulation for mechanical load transmission between joints. Damage to the articular cartilage frequently results from sport-related injuries, systemic diseases, degeneration, trauma, or tumors. Failure to treat impaired cartilage may lead to osteoarthritis, affecting more than 25% of the adult population globally. Articular cartilage has a very low intrinsic self-repair capacity due to the limited proliferative ability of adult chondrocytes, lack of vascularization and innervation, slow matrix turnover, and low supply of progenitor cells. Furthermore, articular chondrocytes are encapsulated in low-nutrient, low-oxygen environment. While cartilage restoration techniques such as osteochondral transplantation, autologous chondrocyte implantation (ACI), and microfracture have been used to repair certain cartilage defects, the clinical outcomes are often mixed and undesirable. Cartilage tissue engineering (CTE) may hold promise to facilitate cartilage repair. Ideally, the prerequisites for successful CTE should include the use of effective chondrogenic factors, an ample supply of chondrogenic progenitors, and the employment of cell-friendly, biocompatible scaffold materials. Significant progress has been made on the above three fronts in past decade, which has been further facilitated by the advent of 3D bio-printing. In this review, we briefly discuss potential sources of chondrogenic progenitors. We then primarily focus on currently available chondrocyte-friendly scaffold materials, along with 3D bioprinting techniques, for their potential roles in effective CTE. It is hoped that this review will serve as a primer to bring cartilage biologists, synthetic chemists, biomechanical engineers, and 3D-bioprinting technologists together to expedite CTE process for eventual clinical applications.

Novel hybrid polyester-polyacrylate hydrogels enriched with platelet-derived growth factor for chondrogenic differentiation of adipose-derived mesenchymal stem cells in vitro

Background

The goal of the present study was to create a new biodegradable hybrid PCL-P (HEMA-NIPAAm) thermosensitive hydrogel scaffold by grafting PNIPAAm-based copolymers with biodegradable polyesters to promote the chondrogenic differentiation of human progenitor cells (adipose-derived stem cells-hASCs) in the presence of the platelet-derived growth factor (PDGF-BB). Different mixture ratios including 50 mmol ε-caprolactone and 10 mmol HEMA (S-1), 30 mmol ε-caprolactone and 10 mmol HEMA (S-2), 10 mmol ε-caprolactone and 30 mmol HEMA (S-3) were copolymerized followed by the addition of NIPAAm.

Results

A mild to moderate swelling and wettability rates were found in S-2 group copmpared to the S-1 ans S-3 samples. After 7 weeks, S-2 degradation rate reached ~ 43.78%. According to the LCST values, S-2, reaching 37 °C, was selected for different in vitro assays. SEM imaging showed nanoparticulate structure of the scaffold with particle size dimensions of about 62–85 nm. Compressive strength, Young’s modulus, and compressive strain (%) of S-2 were 44.8 MPa, 0.7 MPa, and 75.5%. An evaluation of total proteins showed that the scaffold had the potential to gradually release PDGF-BB. When hASCs were cultured on PCL-P (HEMA-NIPAAm) in the presence of PDGF-BB, the cells effectively attached and flattened on the scaffold surface for a period of at least 14 days, the longest time point evaluated, with increased cell viability rates as measured by performing an MTT assay (p < 0.05). Finally, a real-time RT-PCR analysis demonstrated that the combination of PCL-P (HEMA-NIPAAm) and PDGF-BB promoted the chondrogenesis of hASCs over a period of 14 days by up-regulating the expression of aggrecan, type-II collagen, SOX9, and integrin β1 compared with the non-treated control group (p < 0.05).

Conclusion

These results demonstrate that the PCL-P(HEMA-NIPAAm) hydrogel scaffold carrying PDGF-BB as a matrix for hASC cell seeding is a valuable system that may be used in the future as a three-dimensional construct for implantation in cartilage injuries.

Evidence-based indications of platelet-rich plasma therapy

Introduction: Platelet-rich plasma (PRP) is an autologous blood-derived product that contains platelet concentrations at least 2/3 times above the normal level and includes platelet-related growth factors. The concept of PRP began in the 1970s in the field of hematology to treat patients with thrombocytopenia. In the 1980s and 1990s, PRP began to be used in surgical procedures such as maxillofacial surgery and plastic surgery. Since then, PRP had been used in orthopedic procedures, cardiac surgery, sports injuries, plastic surgery, gynecology, urology, and more recently in medical esthetics. Areas covered: This review analyzes the mechanisms of action, current indications, clinical evidence, safety and future directions of PRP in the management of various medical conditions. The literature search methodology included using medical subject headings terms to search in PubMed. Articles used were screened and critically appraised by the coauthors of this review. Expert Opinion: Platelet-rich plasma is a therapeutic option used to treat many medical conditions. PRP could be used alone or in combination with other procedures. The effectiveness and safety of PRP has been demonstrated in many medical scenarios, however there is limited availability of large randomized clinical trials.

Spinal Reflex Recovery after Dorsal Rhizotomy and Repair with Platelet-Rich Plasma (PRP) Gel Combined with Bioengineered Human Embryonic Stem Cells (hESCs)

Dorsal root rhizotomy (DRZ) is currently considered an untreatable injury, resulting in the loss of sensitive function and usually leading to neuropathic pain. In this context, we recently proposed a new surgical approach to treat DRZ that uses platelet-rich plasma (PRP) gel to restore the spinal reflex. Success was correlated with the reentry of primary afferents into the spinal cord. Here, aiming to enhance previous results, cell therapy with bioengineered human embryonic stem cells (hESCs) to overexpress fibroblast growth factor 2 (FGF2) was combined with PRP. For these experiments, adult female rats were submitted to a unilateral rhizotomy of the lumbar spinal dorsal roots, which was followed by root repair with PRP gel with or without bioengineered hESCs. One week after DRZ, the spinal cords were processed to evaluate changes in the glial response (GFAP and Iba-1) and excitatory synaptic circuits (VGLUT1) by immunofluorescence. Eight weeks postsurgery, the lumbar intumescences were processed for analysis of the repaired microenvironment by transmission electron microscopy. Spinal reflex recovery was evaluated by the electronic Von Frey method for eight weeks. The transcript levels for human FGF2 were over 37-fold higher in the induced hESCs than in the noninduced and the wildtype counterparts. Altogether, the results indicate that the combination of hESCs with PRP gel promoted substantial and prominent axonal regeneration processes after DRZ. Thus, the repair of dorsal roots, if done appropriately, may be considered an approach to regain sensory-motor function after dorsal root axotomy.

Evaluation of Autologously Derived Biomaterials and Stem Cells for Bone Tissue Engineering

Despite progress, clinical translation of tissue engineering (TE) products/technologies is limited. A significant effort is underway to develop biomaterials and cells through a minimally modified process for clinical translation of TE products. Recently, bone marrow aspirate (BMA) was identified as an autologous source of cells for TE applications and is currently being tested in clinical therapies, but the isolation methods need improvement to avoid potential for contamination and increase progenitor cell yield. To address these issues, we reproducibly processed human peripheral blood (PB) and BMA to develop autologously derived biomaterials and cells. We demonstrated PB-derived biomaterial/gel cross-linking and fibrin gel formation with varied gelation times as well as biocompatibility through support of human bone marrow-derived stem cell survival and growth in vitro. Next, we established a plastic culture-free process that concentrates and increases the yield of CD146+/CD271+ early mesenchymal progenitor cells in BMA (concentrated BMA [cBMA]). cBMA exhibited increased colony formation and multipotency (including chondrogenic differentiation) in vitro compared with standard BMA. PB-derived gels encapsulated with cBMA also demonstrated increased cell proliferation and enhanced mineralization when assessed for bone TE in vitro. This strategy can potentially be developed for use in any tissue regeneration application; however, bone regeneration was used as a test bed for this study.

A Comprehensive Review of Concentrated Growth Factors and Their Novel Applications in Facial Reconstructive and Regenerative Medicine

BACKGROUND

Concentrated growth factors (CGFs) are the latest generation of platelet concentrates. The objective of developing CGF is to increase therapeutic efficacy. However, few studies have supported the superiority of CGF in composition and efficacy. The reconstruction and regeneration process is complicated and long term, whereas bioactivity of CGF is not durable. The purpose of this review is threefold. The first is to recommend more comparative studies between CGF and other platelet concentrates. The second is to constitute a continuous drug delivery system by combining CGF with other biomaterials. Finally, the novel use of CGF in facial regenerative and reconstructive medicine will be highlighted.

METHODS

A comprehensive review of literature regarding the use of CGF in facial regenerative and reconstructive medicine was performed. Based on the inclusion and exclusion criteria, a total of 135 articles were included.

RESULTS

The use of CGF involving facial rejuvenation, cartilage grafting, facial bone defects, facial peripheral nerve injury and wounding is reviewed. The reconstructive and regenerative principles lie in firm fibrin scaffolds and continuous in situ delivery of multiple growth factors.

CONCLUSIONS

CGF represents an advance in personalized medicine concept. However, the current scientific evidences about the use of CGF are limited. More basic and clinical studies should be conducted to understand the characteristics and clinical application of CGF.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

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

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

Therapeutic Potential of Dental Pulp Stem Cells and Leukocyte- and Platelet-Rich Fibrin for Osteoarthritis

Osteoarthritis (OA) is a degenerative and inflammatory joint disorder with cartilage loss. Dental pulp stem cells (DPSCs) can undergo chondrogenic differentiation and secrete growth factors associated with tissue repair and immunomodulation. Leukocyte- and platelet-rich fibrin (L-PRF) emerges in regenerative medicine because of its growth factor content and fibrin matrix. This study evaluates the therapeutic application of DPSCs and L-PRF in OA via immunomodulation and cartilage regeneration. Chondrogenic differentiation of DPSCs, with or without L-PRF exudate (ex) and conditioned medium (CM), and of bone marrow-mesenchymal stem cells was compared. These cells showed differential chondrogenesis. L-PRF was unable to increase cartilage-associated components. Immature murine articular chondrocytes (iMACs) were cultured with L-PRF ex, L-PRF CM, or DPSC CM. L-PRF CM had pro-survival and proliferative effects on unstimulated and cytokine-stimulated iMACs. L-PRF CM stimulated the release of IL-6 and PGE2, and increased MMP-13, TIMP-1 and IL-6 mRNA levels in cytokine-stimulated iMACs. DPSC CM increased the survival and proliferation of unstimulated iMACs. In cytokine-stimulated iMACs, DPSC CM increased TIMP-1 gene expression, whereas it inhibited nitrite release in 3D culture. We showed promising effects of DPSCs in an in vitro OA model, as they undergo chondrogenesis in vitro, stimulate the survival of chondrocytes and have immunomodulatory effects.

Multifunctional Triple-Layered Composite Scaffolds Combining Platelet-Rich Fibrin Promote Bone Regeneration

There has been substantial progress made in the development of bone regeneration materials, driven by the deficiencies that exist in current clinical products, such as finite sources, donor site complications, and potential for disease transmission. To overcome these shortcomings, multifunctional scaffolds should be developed to integrate the relationship among osteoinduction, osteoconduction, and osseointegration. In this study, we fabricated polycaprolactone/gelatin (PG) nanofiber films by electrospinning, to act as barriers against connective tissue migration into bone defect sites; chitosan/poly (γ-glutamic acid)/hydroxyapatite (CPH) hydrogels were formed by electrostatic interaction and lyophilization, to exert osteoconduction; and platelet-rich fibrin (PRF) was extracted from rat abdominal aorta and combined with composite scaffolds, to promote bone induction through the release of growth factors. Hydrogels were immersed in simulated body fluid (SBF) for 1 month to investigate mineralization in vitro. Cytocompatibility, cell barrier effect, and osteogenic differentiation were also explored in vitro. The ability to effectively regenerate bone was analyzed by implantation of triple-layered composite scaffolds into rat calvarial defects in vivo. Size-matched hydrogel filled the defect site, and then, fresh PRF was applied to the hydrogel surface. Finally, P2G3 nanofiber films were applied and attached to the surrounding soft tissue. In short, we fabricated multifunctional triple-layered scaffolds by combining the advantages of osteoinduction, osteoconduction, and osseointegration, which could give full play to the role of PRF in bone regeneration and provide new and pragmatic concepts for bone tissue regeneration in clinical applications.

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.