Platelet-rich plasma (PRP) contains growth factors that promote tissue regeneration. Previously, we showed that heparin-conjugated fibrin (HCF) exerts the sustained release of growth factors with affinity for heparin. Here, we hypothesize that treatment of skin wound with a mixture of PRP and HCF exerts sustained release of several growth factors contained in PRP and promotes skin wound healing. The release of fibroblast growth factor 2, platelet-derived growth factor-BB, and vascular endothelial growth factor contained in PRP from HCF was sustained for a longer period than those from PRP, calcium-activated PRP (C-PRP), or a mixture of fibrin and PRP (F-PRP). Treatment of full-thickness skin wounds in mice with HCF-PRP resulted in much faster wound closure as well as dermal and epidermal regeneration at day 12 compared to treatment with either C-PRP or F-PRP. Enhanced skin regeneration observed in HCF-PRP group may have been at least partially due to enhanced angiogenesis in the wound beds. Therefore, this method could be useful for skin wound treatment.
angiogenesis inducing agents; endothelial growth factors; fibrin; fibroblast growth factor 2; heparin; neovascularization, physiologic; platelet-derived growth factor; platelet-rich plasma; wound healing
A possible strategy to promote the wound-healing cascade in both soft and hard
tissues is the preparation of an autologous platelet-rich plasma (PRP) to encourage
the release of growth factors from activated platelets. In this process, PRP
combines the advantage of an autologous fibrin clot that will aid in hemostasis as
well as provide growth factors in high concentrations to the site of a tissue
defect. The PRP preparation can be used as a biological enhancer in the healing of
fractures and lumbar fusions. The local application of growth factors seems to
promote initiation and early maturation of bone formation. Autologous bone or bone
substitutes can be added to this mixture to increase the volume of grafting
material. A simplified technique utilizing a commercially available separation
system (GPS—Gravitational Platelet Separation System) is described. This system
provides a less costly alternative to other previously described augmentation
techniques and also presents a patient-friendly and operator-safe alternative.
Further experimental studies of the actual concentrations of the growth factors in
the PRP samples are necessary in order to validate the platelet concentration and
growth-factor activation by laboratory evidence. In further prospective clinical
trials, the safety and efficacy of PRP, in combination with autologous bone or bone
graft substitutes, must be evaluated.
Platelet concentrate; Growth factors; Bone healing; Platelet-rich plasma; GPS
Platelet-rich plasma (PRP) is a new approach to tissue regeneration and it is becoming a valuable adjunct to promote healing in many procedures in dental and oral surgery, especially in aging patients. PRP derives from the centrifugation of the patient's own blood and it contains growth factors that influence wound healing, thereby playing an important role in tissue repairing mechanisms. The use of PRP in surgical practice could have beneficial outcomes, reducing bleeding and enhancing soft tissue healing and bone regeneration. Studies conducted on humans have yielded promising results regarding the application of PRP to many dental and oral surgical procedures (i.e. tooth extractions, periodontal surgery, implant surgery). The use of PRP has also been proposed in the management of bisphosphonate-related osteonecrosis of the jaw (BRONJ) with the aim of enhancing wound healing and bone maturation. The aims of this narrative review are: i) to describe the different uses of PRP in dental surgery (tooth extractions and periodontal surgery) and oral surgery (soft tissues and bone tissue surgery, implant surgery and BRONJ surgery); and ii) to discuss its efficacy, efficiency and risk/benefit ratio. This review suggests that the use of PRP in the alveolar socket after tooth extractions is certainly capable of improving soft tissue healing and positively influencing bone regeneration but the latter effect seems to decrease a few days after the extraction. PRP has produced better results in periodontal therapy in association with other materials than when it is used alone. Promising results have also been obtained in implant surgery, when PRP was used in isolation as a coating material. The combination of necrotic bone curettage and PRP application seem to be encouraging for the treatment of refractory BRONJ, as it has proven successful outcomes with minimal invasivity. Since PRP is free from potential risks for patients, not difficult to obtain and use, it can be employed as a valid adjunct in many procedures in oral and dental surgery. However, further RCTs are required to support this evidence.
PRP; Wound healing; Bone regeneration; Dental surgery; Oral surgery; Tooth extraction; Periodontal surgery; Implant surgery; BRONJ
The underlying rationale of platelet rich plasma (PRP) therapy is that an injection of concentrated PRP at the site of injury may promote tissue repair via cytokine release from platelets. The molecular mechanisms of PRP therapy in the skin wound healing process are not well understood at present, and would benefit from clarification.
PRP was stimulated with angonists for 5 min, and cytokine profile analysis was performed. To investigate the wound healing activity of PRP, cell proliferation and migration analyses were performed in skin cells. The effects of PRP were analyzed on the expression and activity of matrix metalloproteinase (MMP)-1, -2, -9, and the activation of transcription factors.
Thrombin was found to be a strong stimulator of PRP activation to release growth factors and chemokines. PRP induced cell proliferation and migration in HUVECs, HaCaT cells, and HDFs, as well as MMP-1and MMP-9 expression in HaCaT cells, but PRP did not have a significant effect on the expression or activity of MMPs in HDFs. The transcription factors, including signal transducer and activator of transcription-3 (STAT-3) were found to be phosphorylated following PRP treatment in HaCaT cells.
In this study, we have identified the cytokine profile of activated PRP after agonist stimulation. We have shown that PRP plays an active role in promoting the proliferation and migration of skin cells via the regulation of MMPs, and this may be applicable to the future development of PRP therapeutics to enhance skin wound healing.
Platelet rich plasma (PRP); Wound healing; Cytokine profile; Cell proliferation; Cell migration; Matrix metalloproteinase
Autologous platelet concentrates (PCs) have been extensively used in a variety of medical fields to promote soft and hard tissue regeneration. The significance behind their use lies in the abundance of growth factors in platelets α-granules that promotes wound healing. In addition, antibacterial properties of PCs against various bacteria have been recently pointed out. In this study, the antimicrobial effect of pure platelet-rich plasma (P-PRP) was evaluated against oral cavity microorganisms such as Enterococcus faecalis, Candida albicans, Streptococcus agalactiae, Streptococcus oralis and Pseudomonas aeruginosa. Blood samples were obtained from 17 patients who underwent oral surgery procedures involving the use of P-PRP. The antibacterial activity of P-PRP, evaluated as the minimum inhibitory concentration (MIC), was determined through the microdilution twofold serial method.
P-PRP inhibited the growth of Enterococcus faecalis, Candida albicans, Streptococcus agalactiae and Streptococcus oralis, but not of Pseudomonas aeruginosa strains.
P-PRP is a potentially useful substance in the fight against postoperative infections. This might represent a valuable property in adjunct to the enhancement of tissue regeneration.
Platelet concentrate; Oral infection; Antimicrobial effect; Minimum inhibitory concentration; Oral cavity
The economic, social and public health burden of chronic ulcers and other compromised wounds are enormous and rapidly increasing with the aging population. The growth factors derived from platelets play an important role in tissue remodeling including neovascularization. Platelet-rich plasma (PRP) has been utilized and studied for the last four decades. Platelet gel and fibrin sealant, derived from PRP mixed with thrombin and calcium chloride, have been exogenously applied to tissues to promote wound healing, bone growth, hemostasis and tissue sealing. In this study we first characterized recovery and viability of as well as growth factor release from platelets in a novel preparation of platelet gel and fibrin matrix, namely, platelet rich fibrin matrix (PRFM). Next, the effect of PRFM application in a delayed model of ischemic wound angiogenesis was investigated. The study for the first-time shows the kinetics of the viability of platelet embedded fibrin matrix. A slow and steady release of growth factors from PRFM was observed. The VEGF released from PRFM was primarily responsible for endothelial mitogenic response via ERK activation pathway. Finally, this preparation of PRFM effectively induced endothelial cell proliferation and improved wound angiogenesis in chronic wounds, providing evidence of probable mechanisms of action of PRFM in healing of chronic ulcers.
platelet rich plasma (PRP); wound healing; angiogenesis; autologous platelet gels; ischemic wounds
Platelet-rich plasma (PRP) has been clinically used as an easily prepared growth factor cocktail that can promote wound healing, angiogenesis, and tissue remodeling. However, the therapeutic effects of PRP are still controversial, due partly to the lack of optimized and standardized preparation protocols. We used whole blood (WB) samples to optimize the preparation protocols for PRP, white blood cell-containing (W-PRP), platelet-concentrated plasma (PCP), and noncoagulating platelet-derived factor concentrate (PFC). PRP and W-PRP were most efficiently collected by 10 min centrifugation in a 15-mL conical tube at 230–270 g and 70 g, respectively. To prepare PCP, platelets were precipitated by centrifugation of PRP at >2300 g, 90% of supernatant plasma was removed, and the platelets were resuspended. For preparation of noncoagulating PFC, the supernatant was replaced with one-tenth volume of saline, followed by platelet activation with thrombin. Platelet (before activation) and platelet-derived growth factor (PDGF)-BB (after activation) concentrations in PCP were approximately 20 times greater than those in WB, whereas PFC contained a 20-times greater concentration of platelets before platelet activation and a 50-times greater concentration of PDGF-BB without formation of a fibrin gel after platelet activation than WB. Surprisingly, total PDGF-BB content in the PFC was twice that of activated WB, which suggested that a substantial portion of the PDGF-BB became trapped in the fibrin glue, and replacement of plasma with saline is crucial for maximization of platelet-derived factors. As an anticoagulant, ethylene di-amine tetra-acetic acid disodium inhibited platelet aggregation more efficiently than acid citrate dextrose solution, resulting in higher nonaggregated platelet yield and final PDGF-BB content. These results increase our understanding of how to optimize and standardize preparation of platelet-derived factors at maximum concentrations.
Complicated diabetic patients show impaired, delayed wound healing caused by multiple factors. A study on wound healing showed that platelet-rich plasma (PRP) was effective in normal tissue regeneration. Nonetheless, there is no evidence that when plateletrich plasma is applied to diabetic wounds, it normalizes the diabetic wound healing process. In this study, we have analyzed matrix metalloproteinase (MMP)-2, MMP-9 expression to investigate the effect of PRP on diabetic wounds.
Twenty-four-week-old male Otsuka Long-Evans Tokushima Fatty rats were provided by the Tokushima Research Institute. At 50 weeks, wounds were arranged in two sites on the lateral paraspinal areas. Each wound was treated with PRP gel and physiologic saline gauze. To determine the expression of MMP-2, MMP-9, which was chosen as a marker of wound healing, reverse transcription polymerase chain reaction (RT-PCR) was performed and local distribution and expression of MMP-2, MMP-9 was also observed throughout the immunohistochemical staining.
RT-PCR and the immunohistochemical study showed that the levels of MMP-2, MMP-9 mRNA expression in PRP applied tissues were higher than MMP-2, MMP-9 mRNA expression in saline-applied tissues. MMP-9 mRNA expression in wounds of diabetic rats decreased after healing began to occur. But no statistical differences were detected on the basis of body weight or fasting blood glucose levels.
This study could indicate the extracellular matrix-regulating effect observed with PRP. Our results of the acceleration of wound healing events by PRP under hyperglycemic conditions might be a useful clue for future clinical treatment for diabetic wounds.
Platelet-rich plasma; Rats, OLETF; Matrix mtalloproteinase-2; Matrix metalloproteinase-9
Objective: Platelet-rich plasma (PRP) is considered to enhance bone formation especially at early stages of wound
healing, depending on the limited and short life-span of platelets and growth factors. The aim of this study was to
evaluate efficacy of double-application of PRP (DA-PRP) on bone healing in a rabbit calvarial defect model.
Study design: Twenty-eight rabbits, each had two surgically prepared calvarial bone defects (10mm diameter),
were included in this study and randomly divided into six groups. Defects (n=56) were treated with single-application
of PRP (SA-PRP)(n=10), SA-PRP and beta-tricalciumphosphate (SA-PRP+TCP)(n=10), DA-PRP (n=8),
DA-PRP and beta-tricalciumphosphate (DA-PRP+TCP)(n=8), beta-tricalciumphosphate (TCP)(n=10) or left empty
(Control)(n=10). Animals were sacrificed at 30 days postoperatively.
Results: The new bone (NB%) and defect fill (DF%) percentages were calculated from histological slides by
image-analyzer software and statistically analysed. All test groups showed higher NB% than control, but differences
among all groups were insignificant. The TCP treated groups had significantly higher DF% than groups
treated without TCP, however the DF% differences between control, SA-PRP and DA-PRP or TCP, SA-PRP+TCP
or DA-PRP+TCP were insignificant.
Conclusion: Although new bone formation was histomorphologically remarkable at double-application PRP
groups, statistical analyses of the histomorphometric data revealed no significant difference.
Key words: Platelet-Rich Plasma, double application, bone formation, wound healing.
Platelet-rich plasma (PRP) has been increasingly used in sports medicine applications. Platelets are thought to release growth factors important in wound healing, including transforming growth factor (TGF-β1), platelet-derived growth factor (PDGF-AB), and vascular endothelial growth factor (VEGF). However, little is known about the effect of platelet activator choice on growth factor release kinetics.
The choice of platelet activator would affect the timing and level of growth factor release from PRP.
Controlled laboratory study.
Platelet-rich plasma aliquots were activated with either thrombin or collagen. A control group of whole blood aliquots was clotted with thrombin. Supernatant containing the released growth factors was collected daily for 1 week. Levels of TGF-β1, PDGF-AB, and VEGF were measured using enzyme-linked immunosorbent assay (ELISA).
The use of thrombin as an activator resulted in immediate release of TGF-β1 and PDGF-AB, while the collagen-activated PRP clots released similar amounts each day for 5 days. The use of collagen as an activator resulted in an 80% greater cumulative release of TGF-β1 from the PRP aliquots over 7 days (P < .001). Concentrating platelets to 3 times the systemic blood level resulted in a 3-fold higher release of TGF-β1, 2.5-fold greater release of PDGF, and 5-fold greater release of VEGF (all P < .0001) when compared with whole blood control clots, but no significant differences in the timing of release were noted.
These experiments demonstrated that the choice of platelet activator can significantly influence the release kinetics of cytokines from PRP, with thrombin resulting in an immediate release and collagen having a more sustained release pattern.
The level and rate of growth factor release depends on the selected platelet activator, a factor that should be considered when selecting a PRP system for a given application.
blood clot; growth factor; platelet activation; release kinetics
The platelet-rich plasma (PRP) has been advocated as a way to introduce increased concentrations of growth factors and other bioactive molecules to injured tissues in an attempt to optimize the local healing environment. A 94-yr-old woman with various comorbidities presented with a two-week history of severe cutaneous ulcer on the left dorsum of foot. It was caused by recurrent mechanical trauma and did not respond to several wound debridement and simple dressings. However, after she was completed on seven times of autologous PRP treatments, we observed complete healing of the skin lesion within 3 months. Herein, we report a case of recalcitrant cutaneous ulcer with various comorbidities and discuss about the promising possibility of autologous PRP as an effective alternative therapeutic modality.
Platelet Rich Plasma (PRP); Refractory Ulcer; Aged; Diabetes
Platelet-rich plasma (PRP) is an autologous platelet concentrate. It is prepared by separating the platelet fraction of whole blood from patients and mixing it with an agent to activate the platelets. In a clinical setting, PRP may be reapplied to the patient to improve and hasten the healing of tissue. The therapeutic effect is based on the presence of growth factors stored in the platelets. Current evidence in orthopedics shows that PRP applications can be used to accelerate bone and soft tissue regeneration following tendon injuries and arthroplasty. Outcomes include decreased inflammation, reduced blood loss and post-treatment pain relief. Recent shoulder research indicates there is poor vascularization present in the area around tendinopathies and this possibly prevents full healing capacity post surgery (Am J Sports Med36(6):1171–1178, 2008). Although it is becoming popular in other areas of orthopedics there is little evidence regarding the use of PRP for shoulder pathologies. The application of PRP may help to revascularize the area and consequently promote tendon healing. Such evidence highlights an opportunity to explore the efficacy of PRP use during arthroscopic shoulder surgery for rotator cuff pathologies.
PARot is a single center, blinded superiority-type randomized controlled trial assessing the clinical outcomes of PRP applications in patients who undergo shoulder surgery for rotator cuff disease. Patients will be randomized to one of the following treatment groups: arthroscopic subacromial decompression surgery or arthroscopic subacromial decompression surgery with application of PRP.
The study will run for 3 years and aims to randomize 40 patients. Recruitment will be for 24 months with final follow-up at 1 year post surgery. The third year will also involve collation and analysis of the data. This study will be funded through the NIHR Biomedical Research Unit at the Oxford University Hospitals NHS Trust.
Current Controlled Trials: ISRCTN10464365
Platelet-rich-plasma; Rotator cuff; Tendinopathies; Surgery; Growth factors
Venous ulcers are wounds that are thought to occur due to improper functioning of venous valves, usually of the legs. They are the major cause of chronic wounds, occurring in 70% to 90% of chronic wound cases. The treatment of venous ulcers also entails substantial costs. Autologous platelet rich plasma (PRP) is a simple office based procedure which helps in enhancing the wound healing by releasing many growth factors like platelet derived growth factors, fibroblast derived growth factors and epidermal growth factors.
To study the efficacy of autologous platelet rich plasma in the management of chronic venous ulcer.
12 patients with 17 venous ulcers were treated with PRP and treatment outcome was measured by percentage of improvement in area and volume of the ulcer.
12 patients with 17 ulcers were treated with PRP. The mean age of the patients was 33.5 years (SD 9.82). 10 were males and 2 were females. The mean duration of the healing of the ulcers was in 5.1 weeks (SD 3.1). The mean percentage improvement in the area and volume of the ulcer was 94.7% (SD 11.12) and 95.6% (SD 10.19) respectively.
PRP is safe, simple and effective procedure in treating chronic venous ulcers
Non healing; platelet rich plasma; venous ulcers
Platelet-rich plasma (PRP) has recently been found to be a useful delivery system for growth factors important in oral tissue healing. However, application of PRP in a liquid form to a wound site within the oral cavity can be complicated by significant loss of the PRP into the surrounding oral space unless gelation via the clotting mechanism is accomplished. Gelation is currently accomplished using bovine thrombin; however, rare but serious complications of this method have led to the search for alternative clotting mechanisms, including the use of soluble collagen as a clotting activator. In this paper, our hypothesis was that soluble Type I collagen would be as effective as bovine thrombin in causing clotting of the PRP and of stimulating growth factor release from the platelets and granulocytes.
MATERIALS AND METHODS
PRP from human donors was clotted using Type I collagen or bovine thrombin. Clot retraction was determined by measuring clot diameters over time. The release of PDGF-AB, TGF-β1 and VEGF from both types of clots was measured over 10 days using ELISA.
Clots formed using Type I collagen had far less retraction than those formed with bovine thrombin. Bovine thrombin and Type I collagen stimulated similar release of PDGF-AB and VEGF between 1 and 10 days; however, thrombin activation resulted in a greater release of TGF-β1 during the first five days after activation.
The use of Type I collagen to activate clotting of PRP may be a safe and effective alternative to bovine thrombin. The use of collagen results in less clot retraction and equal release of PDGF-AB and VEGF when compared to currently available methods of clot activation.
Platelet-rich Plasma; collagen; thrombin; PDGF-AB; TGF-β1; VEGF
Platelet-rich plasma (PRP) therapy is a recently developed technique that uses a concentrated portion of autologous blood to try to improve and accelerate the healing of various tissues. There is a considerable interest in using these PRP products for the treatment used in bone deficiency healing. Because PRP products are safe and easy to prepare and administer, there has been increased attention toward using PRP in numerous clinical settings. The benefits of PRP therapy appear to be promising, and many investigators are exploring the ways in which this therapy can be used in the clinical setting. At present, the molecular mechanisms of bone defect repair studies have focused on three aspects of the inflammatory cytokines, growth factors and angiogenic factors. The role of PRP works mainly through these three aspects of bone repair. The purpose of this paper is to review the current evidence on the mechanism of the effect of PRP in bone deficiency healing.
Previous topical growth factor studies have shown that recombinant human platelet-derived growth factor-BB isomer (rhPDGF-BB) is an efficacious treatment of chronic diabetic foot ulceration. A newer treatment, autologous platelet-rich plasma (PRP), represents a greater similarity to the natural healing process as a composite of multiple growth factors, is safe due to its autologous nature, and is produced as needed from patient blood. A review of the literature shows few studies performed with scientific rigor, although the safety of PRP appears to be validated. As the use of PRP increases, additional studies may establish PRP as an efficacious treatment modality and guide future treatment of chronic diabetic foot ulceration.
platelet-rich plasma; wounds; wound healing; autologous; therapy; diabetic foot; ulcer
Platelet-derived Growth Factors (GFs) are biologically active peptides that enhance tissue repair mechanisms such as angiogenesis, extracellular matrix remodeling, and cellular effects as stem cells recruitment, chemotaxis, cell proliferation, and differentiation. Platelet-rich plasma (PRP) is used in a variety of clinical applications, based on the premise that higher GF content should promote better healing. Platelet derivatives represent a promising therapeutic modality, offering opportunities for treatment of wounds, ulcers, soft-tissue injuries, and various other applications in cell therapy. PRP can be combined with cell-based therapies such as adipose-derived stem cells, regenerative cell therapy, and transfer factors therapy. This paper describes the biological background of the platelet-derived substances and their potential use in regenerative medicine.
Platelet-rich plasma (PRP) is defined as a portion of the plasma fraction of autologous blood having platelet concentrations above baseline. When activated the platelets release growth factors that play an essential role in bone healing such as Platelet-derived Growth Factor, Transforming Growth Factor-β, Vascular Endothelial Growth Factor and others.
Multiple basic science and in vivo animal studies agree that PRP has a role in the stimulation of the healing cascade in ligament, tendon, muscle cartilage and in bone regeneration in the last years PRP had a widespread diffusion in the treatment of soft tissue and bone healing.
The purpose of this review is to describe the biological properties of platelets and its factors, the methods used for producing PRP, to provide a background on the underlying basic science and an overview of evidence based medicine on clinical application of PRP in bone healing.
growth factors; bone regeneration; Platelet-Rich Plasma.
Musculoskeletal injuries are the most common cause of severe long-term pain and physical disability, and affect hundreds of millions of people around the world. One of the most popular methods used to biologically enhance healing in the fields of orthopaedic surgery and sports medicine includes the use of autologous blood products, namely, platelet rich plasma (PRP). PRP is an autologous concentration of human platelets to supra-physiologic levels. At baseline levels, platelets function as a natural reservoir for growth factors including platelet-derived growth factor (PDGF), epidermal growth factor (EGF), transforming growth factor-beta 1 (TGF-β1), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF), hepatocyte growth factor (HGF), and insulin-like growth factor (IGF-I). PRP is commonly used in orthopaedic practice to augment healing in sports-related injuries of skeletal muscle, tendons, and ligaments. Despite its pervasive use, the clinical efficacy of PrP therapy and varying mechanisms of action have yet to be established. Basic science research has revealed that PRP exerts is effects through many downstream events secondary to release of growth factors and other bioactive factors from its alpha granules. These effects may vary depending on the location of injury and the concentration of important growth factors involved in various soft tissue healing responses. This review focuses on the effects of PrP and its associated bioactive factors as elucidated in basic science research. Current findings in PRP basic science research, which have shed light on its proposed mechanisms of action, have opened doors for future areas of PrP research.
Treatment of gingival recession has become an important therapeutic issue due to increasing cosmetic demand. Multiple surgical procedures have been developed to obtain predictable esthetic root coverage. More specifically, after periodontal regenerative surgery, the aim is to achieve complete wound healing and regeneration of the periodontal unit. A recent innovation in dentistry is the preparation and use of platelet-rich plasma (PRP), a concentrated suspension of the growth factors, found in platelets. These growth factors are involved in wound healing and postulated as promoters of tissue regeneration. This paper reports the use of PRF membrane for root coverage on the labial surfaces of the mandibular anterior teeth. This was accomplished using laterally displaced flap technique with platelet rich fibrin (PRF) membrane at the recipient site.
Plasma rich-derivative (PRF membrane); recession; regeneration; repair
Platelets partake in hemostasis, wound healing and tumor growth. Although platelet-rich-plasma (PRP) has been used in surgery for several years, its mechanism of action and application methods are still poorly characterized.
Materials and Methods
A single unit of human platelets obtained by plateletpheresis was diluted in plasma and divided into three equal volumes. One volume was stored at room temperature as fresh platelets (RT), another volume frozen by storage at −80 °C (FZ) and the third volume frozen at −80 °C with 6% DMSO (FZ6). Plasma (PL) was used as control. Using flow cytometry, platelets were tested for platelet glycoprotein GPIb and annexin V binding, as survival and activation markers, respectively. Hemostatic function was assessed by thromboelastometry.
In vivo, platelets were topically applied on 1 cm2, full-thickness wounds on db/db mice (n=10/group) and healing was staged microscopically and macroscopically.
All platelet preparations showed hemostatic ability. RT platelets were GPIb positive (nonactivated-quiescent platelets) and stimulated angiogenesis by 3-fold, and cell proliferation by 4-fold in vivo. FZ platelets were positive for annexin V, indicating activated platelets and, in vivo, increased only wound granulation. FZ6 platelets contained 30% nonactivated-quiescent and 50% activated platelets and stimulated granulation, angiogenesis, cell proliferation and promoted re-epithelialization in vivo.
Platelets showed distinct mechanisms to induce hemostasis and wound healing. Quiescent platelets are required to induced angiogenesis in vivo. Platelets stored at room temperature and frozen with 6% DMSO and stored at −80 °C achieved optimal wound healing in diabetic mice.
The purpose of this systematic review was to address the treatment of rotator cuff tears by applying tissue engineering approaches to improve tendon healing, specifically platelet rich plasma (PRP) augmentation, stem cells, and scaffolds. Our systematic search was performed using the combination of the following terms: “rotator cuff”, “shoulder”, “PRP”, “platelet rich plasma”, “stemcells”, “scaffold”, “growth factors”, and “tissue engineering”. No level I or II studies were found on the use of scaffolds and stem cells for rotator cuff repair. Three studies compared rotator cuff repair with or without PRP augmentation. All authors performed arthroscopic rotator cuff repair with different techniques of suture anchor fixation and different PRP augmentation. The three studies found no difference in clinical rating scales and functional outcomes between PRP and control groups. Only one study showed clinical statistically significant difference between the two groups at the 3-month follow up. Any statistically significant difference in the rates of tendon rerupture between the control group and the PRP group was found using the magnetic resonance imaging. The current literature on tissue engineering application for rotator cuff repair is scanty. Comparative studies included in this review suggest that PRP augmented repair of a rotator cuff does not yield improved functional and clinical outcome compared with non-augmented repair at a medium and long-term followup.
Chronic pressure ulcers affect patient health, emotional state, and quality of life, causing considerable morbidity and mortality in addition to contributing to significant health care costs from lengthy hospitalizations to advanced home care and surgical care costs. The conventional treatment of these wounds can be slow due to their chronic inflammatory state and the senescence of local reparative cells. Platelet-rich plasma (PRP) therapy has been growing as a viable treatment alternative for a number of clinical applications and has potential benefit for use in chronic wounds. The sustained release of large quantities of autologous growth factors, cytokines, and other mediators found in PRP plus the favorable mononuclear cell profile of PRP may help us to stimulate wound healing and resolve chronic inflammation.
Three veterans with spinal cord injury (SCI), presenting with chronic stage IV pressure ulcers, were treated with a sustained release PRP therapy to stimulate wound healing.
PRP treatment consistently resulted in the formation of granulation tissue and improved vascularity for each of the three patients treated, while reducing the overall ulcer area and volume.
The controlled release of growth factors from PRP demonstrated a positive stimulatory effect on the healing rate of chronic pressure ulcers in individuals with SCI.
Spinal cord injuries; Pressure ulcers; Tetraplegia; Paraplegia; Wound healing; Platelet-rich plasma therapy
Platelet-rich plasma (PRP) is an autogenous source of growth factor and has been shown to enhance bone healing both in clinical and experimental studies. PRP in combination with porous hydroxyapatite has been shown to increase the bone ingrowth in a bone chamber rat model. The present study investigated whether the combination of beta tricalcium phosphate (β-TCP) and PRP may enhance spinal fusion in a controlled animal study. Ten Danish Landrace pigs were used as a spinal fusion model. Immediately prior to the surgery, 55 ml blood was collected from each pig for processing PRP. Three-level anterior lumbar interbody fusion was performed with carbon fiber cages and staples on each pig. Autogenous bone graft, β-TCP, and β-TCP loaded with PRP were randomly assigned to each level. Pigs were killed at the end of the third month. Fusion was evaluated by radiographs, CT scanning, and histomorphometric analysis. All ten pigs survived the surgery. Platelet concentration increased 4.4-fold after processing. Radiograph examination showed 70% (7/10) fusion rate in the autograft level. All the levels with β-TCP+PRP showed partial fusion, while β-TCP alone levels had six partial fusions and four non-fusions (P=0.08). CT evaluation of fusion rate demonstrated fusion in 50% (5/10) of the autograft levels. Only partial fusion was seen at β-TCP levels and β-TCP+PRP levels. Histomorphometric evaluation found no difference between β-TCP and β-TCP+PRP levels on new bone volume, remaining β-TCP particles, and bone marrow and fibrous tissue volume, while the same parameters differ significantly when compared with autogenous bone graft levels. We concluded from our results in pigs that the PRP of the concentration we used did not improve the bone-forming capacity of β-TCP biomaterial in anterior spine fusion. Both β-TCP and β-TCP+PRP had poorer radiological and histological outcomes than that of autograft after 3 months.
Spinal fusion; Bone substitute; Platelet-rich plasma; Tricalcium phosphate; Pig
Platelet-rich plasma (PRP) is nowadays widely applied in different clinical scenarios, such as orthopedics, ophthalmology and healing therapies, as a growth factor pool for improving tissue regeneration. Studies into its clinical efficiency are not conclusive and one of the main reasons for this is that different PRP preparations are used, eliciting different responses that cannot be compared. Platelet quantification and the growth factor content definition must be defined in order to understand molecular mechanisms behind PRP regenerative strength. Standardization of PRP preparations is thus urgently needed.
PRP was prepared by centrifugation varying the relative centrifugal force, temperature, and time. Having quantified platelet recovery and yield, the two-step procedure that rendered the highest output was chosen and further analyzed. Cytokine content was determined in different fractions obtained throughout the whole centrifugation procedure.
Our method showed reproducibility when applied to different blood donors. We recovered 46.9 to 69.5% of total initial platelets and the procedure resulted in a 5.4-fold to 7.3-fold increase in platelet concentration (1.4 × 106 to 1.9 × 106 platelets/μl). Platelets were highly purified, because only <0.3% from the initial red blood cells and leukocytes was present in the final PRP preparation. We also quantified growth factors, cytokines and chemokines secreted by the concentrated platelets after activation with calcium and calcium/thrombin. High concentrations of platelet-derived growth factor, endothelial growth factor and transforming growth factor (TGF) were secreted, together with the anti-inflammatory and proinflammatory cytokines interleukin (IL)-4, IL-8, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-α. No cytokines were secreted before platelet activation. TGF-β3 and IFNγ were not detected in any studied fraction. Clots obtained after platelet coagulation retained a high concentration of several growth factors, including platelet-derived growth factor and TGF.
Our study resulted in a consistent PRP preparation method that yielded a cytokine and growth factor pool from different donors with high reproducibility. These findings support the use of PRP in therapies aiming for tissue regeneration, and its content characterization will allow us to understand and improve the clinical outcomes.
Platelet-rich plasma; Centrifugation; Growth factors; Cytokine; Activation