Platelet concentration and its effect on bone formation in calvarial defects: an experimental study in rabbits

Osseointegration and Histopathological Evaluation of Titanium-Titanium Diboride Composite Compared to Pure Titanium Implant Materials Prepared by Powder Metallurgy (In Vivo Study)

The efficacy and osseointegration rate of an implant depend on its biocompatibility. Modern implantology seeks fast and reliable osseointegration, which is essential for clinical success. The objective of this research was to assess the osseointegration and biocompatibility of a titanium-titanium diboride composite (Ti-TiB2) in rabbits in contrast to those of pure titanium (Ti). A total of 64 cylindrical implant specimens were fabricated, consisting of two sets: pure Ti (32 implants) and Ti-TiB2 composite (32 implants). In this study, two implants were implanted per tibia (left and right tibias) in 16 white male New Zealand rabbits, for a total of four implants per rabbit (4 × 16 = 64 implants). A pushout test was used to assess implant specimen-bone bonding after 2 and 6 weeks of healing. The experiment utilized five rabbits per healing phase, which means that 20 implants per time point were used for the pushout tests. (10 for pure Ti and 10 for the composite). Histology was used to examine the tissue response to biocompatibility, and histomorphometry was used to measure new bone growth at the two time points. With three rabbits per time point, 12 implants were employed for the histological analyses. After implantation, the pushout shear strength results revealed that the mean shear strength of the Ti-TiB2 implant specimens (5.4 ± 0.029 MPa for 2 weeks, 7.9 ± 0.029 MPa for 6 weeks) was statistically greater (p < 0.0001) than that of the pure Ti implant specimens (5.1 ± 0.015 MPa for 2 weeks, 6.6 ± 0.047 MPa for 6 weeks). After 2 weeks, woven bone tissues were observed around the pure titanium implants, and active osteoid tissue around the composite implants exhibited significant differences in new bone formation areas (NBFAs) (0.54 ± 0.004 mm2 for Ti and 0.65 ± 0.003 mm2 for the composite). After 6 weeks, there was new bone formation with osteocytes around the pure titanium implants (NBFA of 2.44 mm2) and osteoid maturation with the observation of reversal lines around the composite implants (NBFA of 2.89 mm2). The developed Ti-TiB2 material was biocompatible and demonstrated superior bone growth compared to that of the pure Ti materials after 2 and 6 weeks.

Multi-walled carbon nanotube/hydroxyapatite nanocomposite with leukocyte- and platelet-rich fibrin for bone regeneration in sheep model

BACKGROUND

The aim of this study was to evaluate the effects of multi-walled carbon nanotubes/hydroxyapatite (MWCNT/HA) granules with or without leukocyte- and platelet-rich fibrin (L-PRF) on bone regeneration in cancellous bone of sheep model.

METHODS

Totally, 32 cylindrical holes were drilled in female sheep (n = 4) in the distal epiphysis and proximal metaphysis of right and left humerus and femur. The defects were randomly filled with (1) MWCNT/HA, (2) MWCNT/HA mixed with L-PRF, (3) L-PRF, and (4) left empty as control. After 8 weeks, defects were evaluated and compared radiographically using multi-slice computed tomographic (CT) scan and cone beam CT scans, histologically and histomorphometrically.

RESULTS

The results showed that there was no significant inflammation (> 10%) or foreign body reaction around the granules. The new lamellar bone was regenerated around the MWCNT/HA nanocomposite granules. Addition of L-PRF to MWCNT/HA demonstrated significantly improvement of new bone formation, about 27.40 ± 1.08%, in comparison with the L-PRF alone, about (12.16 ± 1.46%) (P < 0.01). Also, the rate of new bone formation was significantly greater with the use of MWCNT/HA granules (24.59 ± 1.54%) compared to the control (10.36 ± 1.17%) (P < 0.01).

CONCLUSION

Consequently, both biocompatibility and osteoconductivity of MWCNT/HA nanocomposite were demonstrated in the preclinical sheep model, and the use of L-PRF in combination with MWCNT/HA nanocomposite can improve bone regeneration.

Comparative study of bone regeneration using fibrin sealant with xenograft in rabbit sinus: pilot study

Background

Stability of the grafted bone volume is one of the important factors to the success of alveolar bone grafts. For this, platelet-rich plasma (PRP) or fibrin sealant is mixed with the bone graft material. Bio-Oss® is a protein-free bovine mineral commonly used in bone graft procedures. The grafting particles are commonly combined with a standard fibrin sealant (Tisseel®) to fabricate a plastic implantable product. The purpose of this experiment was to evaluate the efficacy of fibrin sealant (Tisseel®) in bone regeneration performance in a rabbit maxillary sinus model.

Methods

A total of five 3.5 kg weight New Zealand white rabbits were used for the study. After elevating the sinus membrane in both maxillary sinus cavities, Bio-Oss® mixed with normal saline (group 1) was filled into the right side, and Tisseel® mixed Bio-Oss® (group 2) was inserted into the other side. The bone mineral density and bone volume were analyzed with microscopic computed tomography (micro-CT) and histomorphometric 12 weeks after application.

Results

Histologically, new bone formation rate was 14.8%, and grafted bone rate was 70.5% in group 1. In group 2, they were 18.5% and 60.4%, respectively. According to micro-CT analysis, bone mineral density (mg/cm³, BMD) was 2.5% larger in group 1.

Conclusions

The findings from this study suggest that, although the difference in the bone formation between group 1 and group 2 appears to be insignificant, group 2 had an advantage in using smaller amount of bone substances to achieve the reliable bone formation.

Comparative in vitro study on binary Mg-RE (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) alloy systems

Correct selection of alloying elements is important for developing novel biodegradable magnesium alloys with superior mechanical and biological performances. In contrast to various reports on nutrient elements (Ca, Zn, Sr, etc.) as alloying elements of biomedical magnesium alloys, there is limited information about how to choose the right rare earth elements (REEs) as alloying elements of magnesium. In this work, 16 kinds of REEs were individually added into Mg, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Du, Ho, Er, Tm, Yb and Lu, to fabricate binary Mg-RE model alloys with different composition points. Under the same working history, comparative studies were undertaken and the impact of each kind of rare earth element on the microstructure, mechanical property, corrosion behavior and biocompatibility of Mg were investigated. The corresponding influence level for the 16 kinds of REEs were ranked. The results showed that the second phases were detected in some Mg-RE alloys, which were mainly composed of Mg₁₂RE. By adding different REEs into Mg with proper contents, the mechanical properties of resulting Mg-RE binary alloys could be adjusted in wide range. The corrosion resistance of Mg-light REE alloys was generally better than Mg-heavy REE alloys. As for biocompatibility, Mg-RE model alloys showed no cytotoxic effect on MC3T3-E1 cells. The hemolysis rates of all experimental Mg-RE model alloys were lower than 5% except for Mg-Lu alloy model. In general, the addition of different REEs into Mg could improve its performance from different aspects. This work provides a better understanding on suitable REEs as alloying elements for magnesium, and the future R&D direction on biomedical Mg-RE alloys was proposed. STATEMENT OF SIGNIFICANCE: In contrast to various reports on nutrient elements (Ca, Zn, Sr, etc.) as alloying elements of biomedical magnesium alloys, until now there is limited information about how to choose the right rare earth elements (REEs) as alloying elements of magnesium. In this work, comparative studies were undertaken by individually adding 16 kinds of REEs, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Du, Ho, Er, Tm, Yb and Lu, into Mg to fabricate binary Mg-RE model alloys, with different composition points, then the impact of each kind of rare earth element on the microstructure, mechanical property, corrosion behavior and biocompatibility of Mg under the same working history were investigated, and the corresponding influence level for the 16 kinds of REEs were ranked. This work provides a better understanding on suitable REEs as alloying elements for magnesium, and the future R&D direction on biomedical Mg-RE alloys was proposed.

Efficacy of Combining PRP and MMP Inhibitors in Treating Moderately Damaged Tendons Ex Vivo

Platelet-rich plasma (PRP) and broad-spectrum matrix metalloproteinase inhibitors (MMPIs) have been used as therapeutic options for tendinopathy. However, mixed results have been reported regarding their efficacy. We posited that the combination of these two treatment strategies would be more beneficial for healing tendons than each treatment alone. Rat tail tendons were harvested and cultured without mechanical stress for 0, 4, or 10 days. Single and combination treatment with PRP and MMPIs with either broad- or narrow-spectrum (MMP-13 selective), was administered to 4-day stress-deprived (SD) tendons, an ex vivo model for moderate tendinopathy. This treatment was applied to the damaged tendons over 6 days. At the end of their culture time, the tendons were subjected to traction testing and pathohistology, immunohistochemistry, and viability assays. The results showed better histological features for the PRP + narrow-spectrum MMPI group compared with all individual treatment modalities. Moreover, higher fiber density, more elongated nucleus shape, smaller space between fibers, and a trend toward higher mechanical strength were noted for PRP + narrow-spectrum MMPI group compared with 10-day SD tendons. This study shows that the combination of PRP + narrow-spectrum MMPI is a potentially effective treatment approach for tendinopathy. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1838-1847, 2019.

Platelet concentrate as an additive to bone allografts: a laboratory study using an uniaxial compression test

Chemical cleaning procedures of allografts are destroying viable bone cells and denaturing osteoconductive and osteoinductive proteins present in the graft. The aim of the study was to investigate the mechanical differences of chemical cleaned allografts by adding blood, clotted blood; platelet concentrate and platelet gel using a uniaxial compression test. The allografts were chemically cleaned, dried and standardized according to their grain size distribution. Uniaxial compression test was carried out for the four groups before and after compacting the allografts. No statistically significant difference was found between native allografts, allografts mixed with blood, clotted blood, platelet concentrate and platelet concentrate gel regarding their yield limit after compaction. The authors recommend to chemical clean allografts for large defects, optimize their grain size distribution and add platelet concentrate or platelet rich plasma for enhancing as well primary stability as well bone ingrowth.

Progress in TiO2 nanotube coatings for biomedical applications: a review

Titanium dioxide nanotubes (TNTs) have drawn wide attention and been extensively applied in the field of biomedicine, due to their large specific surface area, good corrosion resistance, excellent biocompatibility, and enhanced bioactivity. This review describes the preparation of TNTs and the surface modification that entrust the nanotubes with better antibacterial property and enhanced osteoblast adhesion, proliferation, and differentiation. Considering the contact between TNTs' surface and surrounding tissues after implantation, the interactions between TNTs (with properties including their diameter, length, wettability, and crystalline phase) and proteins, platelets, bacteria, and cells are illustrated. The state of the art in the applications of TNTs in dentistry, orthopedic implants, and cardiovascular stents are introduced. In particular, the application of TNTs in biosensing has attracted much attention due to its ability for the rapid diagnosis of diseases. Finally, the difficulties and challenges in the practical application of TNTs are also discussed.

Can gray values derived from CT and cone beam CT estimate new bone formation? An in vivo study

OBJECTIVES

The main aim of this study was to investigate whether Hounsfield unit derived from computed tomography (HU/CT) and gray value derived from cone beam computed tomography (GV/CBCT) can predict the amount of new bone formation (NBF) in the defects after bone reconstruction surgeries.

MATERIALS AND METHODS

Thirty calvaria defects created in 5 rabbits and grafted with both radiolucent (RL, n = 15) and radiopaque (RO, n = 15) bone substitute materials were evaluated, 8 weeks postoperatively. The defects were scanned by multislice computed tomography (Somatom®, Siemens Healthineers, Erlangen, Germany) and CBCT (NewTom VG®, Qualitative Radiology, Verona, Italy). MSCT and CBCT scans were matched to select the exact region of interest (ROI, diameter = 5 mm and height = 1 mm). HU/CT and GV/CBCT of each ROI were obtained. Mean amount of NBF in whole of the defects was measured using serial histomorphometric assessment. We investigated the correlation between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF generally, and separately among the RL or RO grafted defects, by linear generalized estimating equation modeling. Receiver operation characteristic analysis was performed to check the accuracy of HU/CT and GV/CBCT in diagnosing more than 10% NBF in the samples.

RESULTS

There were linear correlations between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF.

CONCLUSION

According to the results, both HU/CT and GV/CBCT can be considered as fairly good predictors for assessment of the amount of NBF following bone reconstruction surgeries.

Platelet-Rich Plasma Injections as a Treatment for Refractory Patellar Tendinosis: A Meta-Analysis of Randomised Trials

Purpose

Patellar tendinosis (PT) is a common condition amongst athletes. In this study, we perform a meta-analysis on randomised controlled trials (RCTs) to evaluate the use of platelet-rich plasma (PRP) for refractory PT.

Methods

A literature search was undertaken in various databases from their year of inception to October 2015. The primary outcome measure was the Victorian Institute of Sports Assessment-Patella (VISA-P) score.

Results

We identified 2 RCTs comparing PRP injections to alternative treatment options (extracorporeal shockwave therapy [ESWT] and dry needling of the tendon). Meta-analysis showed no significant difference in mean VISA-P scores between PRP injection and control at early assessment (2 or 3 months; estimated difference in means, 11.9; standard error [SE], 7.4; 95% confidence interval [CI], -2.7 to 26.4; p=0.109). However, PRP was statistically better than control with regards to VISA-P scores at longer follow-up (6 months or longer; estimated difference in means, 12.7; SE, 4.4; 95% CI, 4.1 to 21.3; p=0.004).

Conclusions

There is a paucity of RCTs evaluating the role of PRP in PT. Our results suggest that, based on limited evidence, PRP is superior over other established non-surgical treatments (dry needling and ESWT) for refractory PT. Larger RCTs may allow better characterisation of the role of PRP in this condition.

Efficacy of platelets in bone healing: A systematic review on animal studies

In presence of large bone defects, delayed bone union, non-union, fractures, and implant surgery, bone reconstruction may be necessary. Different strategies have been employed to enhance bone healing among which the use of autologous platelet concentrates. Due to the high content of platelets and platelet-derived bioactive molecules (e.g., growth factors, antimicrobial peptides), they are promising candidates to increase bone healing. However, a high heterogeneity of both preclinical and clinical studies resulted in contrasting results. Aim of the present systematic review was to evaluate the efficacy of platelet concentrates in animal models of bone regeneration, considering the possible factors which might affect the outcome. An electronic search was performed on MEDLINE and SCOPUS databases. Animal studies with a minimum follow up of 2 weeks and a sample size of five subjects per group, using platelet concentrates for bone regeneration, were included. Articles underwent risk of bias assessment and further quality evaluation was done. Sixty studies performed on six animal species (rat, rabbit, dog, sheep, goat, and mini-pig) were included. The present part of the review considers only studies performed on rats and rabbits (35 articles). The majority of the studies were considered at medium risk of bias. Animal species, healthy models, platelet, growth factors and leukocytes concentration, and type of bone defect seemed to influence the efficacy of platelet concentrates in bone healing. However, final conclusions were not be drawn, since only few included studies evaluated leukocyte, growth factor content, or presence of other bioactive molecules in platelet concentrates. Further studies with a standardized protocol including characterization of the final products will provide useful information for clinical application of platelet concentrates in bone surgery.

Hybrid composites of mesenchymal stem cell sheets, hydroxyapatite, and platelet-rich fibrin granules for bone regeneration in a rabbit calvarial critical-size defect model

The reconstruction of large bone defects remains a major clinical challenge, and tissue engineering is a promising technique for resolving this problem. Many attempts have been made to optimize bone tissue engineering protocols. The aim of the present study was to develop a process incorporating mesenchymal stem cell (MSC) sheets with nanoscale hydroxyapatite (nano-HA) and autologous platelet-rich fibrin (PRF) granules for enhanced bone formation within a critical-sized rabbit cranial defect. MSC sheets and PRF were prepared prior to in vivo experiments. The osteogenic differentiation ability of MSCs and the ultrastructure of PRF were also studied. A total of 15 New Zealand white rabbits were used in the current study and critical-size defects (CSDs) were surgically introduced in the cranium (diameter, 15 mm). The surgical defects were treated with MSC/PRF composites, MSC composites or left empty. Animals were euthanized at week 8 post-surgery. Iconography, histological and histomorphometric analysis were performed to assess de novo bone formation. The percentage of new bone in the MSC/PRF group (35.7±5.1%) was significantly higher than that in the MSC (18.3±3.2%; P<0.05) and empty defect groups (4.7±1.5%; P<0.05). The results of the present study suggest that combined application of an MSC sheet with nano-HA and granular PRF enhances bone regeneration in a rabbit calvarial CSD model, and provides a novel insight into bone tissue regeneration for large bone defects.

Acceleration of osteogenesis by platelet-rich plasma with acellular dermal matrix in a calvarial defect model

PURPOSE

The effects of platelet-rich plasma (PRP) on improvement of bone regeneration have been widely investigated. However, use of a proper scaffold is also important to the delivery of bioactive materials. The aim of this study was to analyze the effects of PRP with acellular dermal matrix (ADM) as a bone substitute in a cranial defect model.

METHODS

Twenty-nine New Zealand white rabbits were randomly divided into four groups including control, PRP, ADM, and PRP with ADM. A 15 × 15-mm(2) bony defect was carefully created in the cranium. The experimental materials were applied in each group. After 16 weeks, the volume and surface area of new bone were measured using three-dimensional computed tomography and digital photography, and the new bone was analyzed histologically.

RESULTS

The PRP with ADM group exhibited a statistically significant increase in volume and surface area of newly formed bone compared with the other groups (p < 0.05). Histological findings revealed compact lamellar bone in the PRP with ADM group. In contrast, scattered bone islands were detected within the fibrous connective tissue in the other groups.

CONCLUSIONS

The regeneration of mature and augmented bone was achieved following the application of PRP mixed with ADM. The results indicated that the PRP combined with ADM could be a potentially useful substitute for bone and may aid in the elimination of additional donor-site harvest procedures.

Comparison of Effects of Pulsed Electromagnetic Field Stimulation on Platelet-Rich Plasma and Bone Marrow Stromal Stem Cell Using Rat Zygomatic Bone Defect Model

BACKGROUND

Reconstruction of bone defects that occur because of certain reasons has an important place in plastic and reconstructive surgery. The objective of the treatments of these defects was to reinstate the continuity of tissues placed in the area in which the defect has occurred. In this experimental study, the effect of pulsed electromagnetic field stimulation on platelet-rich plasma (PRP) and bone marrow stromal cell, which propounded that they have positive impact on bone regeneration, was evaluated with the bone healing rate in the zygomatic bone defect model enwrapped with superficial temporal fascia.

METHODS

After creating a 4-mm defect on the zygomatic bone of the experiments, the defect was encompassed with a superficial temporal fascial flap and a nonunion model was created. After surgery, different combinations of the PRP, bone marrow stromal cell, and electromagnetic field applications were implemented on the defective area. All the experiments were subjected to bone density measurement.

RESULTS

The result revealed that the PRP and pulsed electromagnetic field implementation were rather a beneficial and an effective combination in terms of bone regeneration.

CONCLUSIONS

It was observed that the superficial temporal fascial flap used in the experiment was a good scaffold choice, providing an ideal bone regeneration area because of its autogenous, vascular, and 3-dimensional structures. As a result, it is presumed that this combination in the nonhealing bone defects is a rather useful treatment choice and can be used in a reliable way in clinical applications.

Autologous blood preparations rich in platelets, fibrin and growth factors

OBJECTIVES

Bone regeneration is often needed prior to dental implant treatment due to the lack of adequate quantity and quality after infectious diseases. The greatest regenerative power was obtained with autologous tissue, primarily the bone alive, taken from the same site or adjacent sites, up to the use centrifugation of blood with the selection of the parts with the greatest potential regenerative. In fact, various techniques and technologies were chronologically successive to cope with an ever better preparation of these concentrates of blood. Our aim is to review these advances and discuss the ways in which platelet concentrates may provide such unexpected beneficial therapeutic effects.

METHODS

The research has been carried out in the MEDLINE and Cochrane Central Register of Controlled Trials database by choosing keywords as "platelet rich plasma", "platelet rich fibrin", "platelet growth factors", and "bone regeneration" and "dentistry".

RESULTS

Autologous platelet rich plasma is a safe and low cost procedure to deliver growth factors for bone and soft tissue healing.

CONCLUSION

The great heterogeneity of clinical outcomes can be explained by the different PRP products with qualitative and quantitative difference among substance.

Platelet-rich plasma: quantitative assessment of growth factor levels and comparative analysis of activated and inactivated groups

Background

Platelet-rich plasma (PRP) has more concentrated platelets than normal plasma (approximately 150-400×10³ cell/dL). Platelets excrete several growth factors and cytokines that are associated with the healing and regeneration process. However, even though PRP is widely used, the mechanism or actual effect is presently unclear. Therefore, this study was performed to investigate the levels of growth factors and platelet concentration rate.

Methods

Autologous blood for preparing PRP was obtained from healthy subjects aged 25 to 35 years. The samples were divided into 4 experimental groups (inactivated whole blood, inactivated PRP, activated whole blood with thrombin and calcium chloride, and activated PRP). The platelet counts in the blood were analyzed and the growth factors were quantitatively measured. A statistical analysis was performed by using Dunn's multiple comparison test.

Results

In the blood cell analysis, the platelet count of the PRP group was approximately 4.25 times higher than that of the whole blood group. In the quantitative analysis of growth factors, the platelet-derived growth factor (PDGF)-AB, PDGF-BB, and transforming growth factor-β of the inactivated and activated PRP groups were higher than those of the inactivated and activated whole blood groups (P<0.05).

Conclusions

In this study, the platelet count and the levels of PDGF-AB and PDGF-BB in the PRP were determined. Further, more research is required on the bioactivity level of the growth factors secreted during the process of PRP preparation and the potency of growth factors that can be exerted physiologically in vivo.

A comparative study of the regenerative effect of sinus bone grafting with platelet-rich fibrin-mixed Bio-Oss® and commercial fibrin-mixed Bio-Oss®: an experimental study

Anorganic bovine bone (Bio-Oss®) particles are one of the most popular grafting materials. The particles are often mixed with platelet-rich fibrin (PRF) or a commercial fibrin (Tisseel®) to form a mouldable graft material. The objective of this study was to compare the potentials of PRF-mixed Bio-Oss® and Tisseel®-mixed Bio-Oss® to enhance bone regeneration in a canine sinus model. Six mongrel dogs were used in this study. After elevating the sinus membrane in both maxillary sinus cavities, an implant was placed into the sinus cavity. In one of the sinus cavities, the PRF/Bio-Oss® composite was grafted, and the Tisseel®/Bio-Oss® composite was grafted in the other sinus cavity. After a 6 month healing period, bone formation in the graft sites and bone-implant contact were evaluated. The mean osseointegration rate was 43.5 ± 12.4% and new bone formation rate 41.8 ± 5.9% in the PRF/Bio-Oss® composite sites. In the Tisseel®/Bio-Oss® composite sites they were 30.7 ± 7.9% and 31.3 ± 6.4%. There were statistically significant differences between the groups. The findings from this study suggest that when platelet-rich fibrin is used as an adjunct to Bio-Oss® particles for bone augmentation in the maxillary sinus, bone formation in the graft sites is significantly greater than when Tisseel® is used.

Repair of calvarial defects in rabbits with platelet-rich plasma as the scaffold for carrying bone marrow stromal cells

OBJECTIVE

Platelet-rich plasma (PRP) is becoming a new application in tissue engineering and a developing area for clinicians and researchers because it is a natural source of growth factors, many of which can accelerate and promote bone regeneration. However, few studies have reported the potentiality of using PRP as a scaffold in bone tissue engineering. The present study investigated the feasibility of using PRP as a scaffold to carry bone marrow stromal cells (BMSCs) to repair calvarial defects in a rabbit model.

STUDY DESIGN

The primary cultured BMSCs were divided into 2 groups. One group was induced with dexamethasone and the other was not induced. Full-thickness bone defects of 5-mm diameter (4 defects per calvarium) were created on the calvaria of 10 New Zealand white rabbits. PRP or whole blood was used, respectively to incorporate the induced or uninduced BMSCs. Then, the composites were activated and applied to repair the defects. The samples were harvested 8 weeks later and bone regeneration was assessed grossly and analyzed by radiographic or histologic examination.

RESULTS

Eight weeks after the implantation of the materials, substantial bone regeneration was observed at the calvarial defect restored with PRP incorporating the induced BMSCs. Less new bone formation was observed at the defect implanted with PRP incorporating the uninduced BMSCs. In contrast, no bone regeneration was detected at the defects implanted with the whole blood incorporating BMSCs, whether the BMSCs were induced or not.

CONCLUSIONS

PRP can be used as a scaffold to carry in vitro expanded BMSCs to repair a rabbit's calvarial defect, but its inductive ability to BMSCs was limited.

Platelet-rich plasma versus focused shock waves in the treatment of jumper's knee in athletes

BACKGROUND

Tendinopathies represent a serious challenge for orthopaedic surgeons involved in treatment of athletes.

PURPOSE

To compare the effectiveness and safety of platelet-rich plasma (PRP) injections and focused extracorporeal shock wave therapy (ESWT) in athletes with jumper's knee.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Forty-six consecutive athletes with jumper's knee were selected for this study and randomized into 2 treatment groups: 2 autologous PRP injections over 2 weeks under ultrasound guidance (PRP group; n = 23), and 3 sessions of focused extracorporeal shock wave therapy (2.400 impulses at 0.17-0.25 mJ/mm(2) per session) (ESWT group; n = 23). The outcome measures were Victorian Institute of Sports Assessment-Patella (VISA-P) questionnaire, pain visual analog scale (VAS), and modified Blazina scale. A reviewer who was blinded as to the group allocation of participants performed outcome assessments before treatment and at 2, 6, and 12 months after treatment. Nonparametric tests were used for within-group (Friedman/Wilcoxon test) and between-group (Kruskal-Wallis/Fisher test) testing, and the significance level was set at .05.

RESULTS

The 2 groups were homogeneous in terms of age, sex, level of sports participation, and pretreatment clinical status. Patients in both groups showed statistically significant improvement of symptoms at all follow-up assessments. The VISA-P, VAS, and modified Blazina scale scores showed no significant differences between groups at 2-month follow-up (P = .635, .360, and .339, respectively). The PRP group showed significantly better improvement than the ESWT group in VISA-P, VAS scores at 6- and 12-month follow-up, and modified Blazina scale score at 12-month follow-up (P < .05 for all).

CONCLUSION

Therapeutic injections of PRP lead to better midterm clinical results compared with focused ESWT in the treatment of jumper's knee in athletes.

Platelet rich plasma therapy: A comparative effective therapy with promising results in plantar fasciitis

Chronic muscle & tendon injuries are one of the problems which are encountered by human being since last long time. These injuries are generally repetitive strain injuries, commonly found in athletes. There are various treatments which include conservative methods in initial stages to surgery in later stages. On minimal invasive aspect Ultrasound-guided fenestration and tenotomy surgery has been used with good results as an effective treatment of chronic tendinopathies.(1,2) There are various injectable agents which were also researched including simple solutions such as hyperosmolar dextrose(3) (prolotherapy) to complex orthobiologic agents such as bone morphogenic protein,(4) but none have achieved uniform success. Platelet rich plasma (PRP) injection has emerged as a treatment alternative for many musculoskeletal conditions. We have done this study on sixty patients to evaluate & compare the effects of platelet rich plasma & steroid injection on patients with planter fasciitis. The results at the 1, 3 & 6 months were evaluated, which showed the good results with platelet rich plasma in comparison to steroid injections.

Autologous platelet-poor plasma decreases the bronchial stump necrosis in rat

BACKGROUND

Necrosis of the bronchial stump is a very important trigger for bronchopleural fistula. The administration of local autologous platelet-poor plasma (PPP) could protect the bronchial stump.

MATERIALS AND METHODS

Left pneumonectomy was performed in 25 Sprague-Dawley rats. Animals were randomly assigned to a control group (n=13) and PPP group (n=12). PPP was locally administered on the bronchial stump after pneumonectomy. We analyzed histologic changes in the bronchial stump and messenger RNA expression changes of genes involved in wound repair at 10 and 20 d.

RESULTS

Local PPP treatment produced a mass of fibrous tissue surrounding the bronchial stump and significantly decreased the presence of necrosis at 20 d. PPP increased the expression of insulin like growth factor 1 at 10 d although it did not reach statistical significance.

CONCLUSIONS

Our findings indicate that local PPP treatment of the bronchial stump after pneumonectomy decreased necrosis and could have a protective effect on the bronchial stump.

Platelet-rich plasma-loaded chitosan scaffolds: preparation and growth factor release kinetics

The aim of this study is to compare the effects of different platelet-rich plasma (PRP) preparation methods on platelet activity and to investigate the growth factor (GF) release kinetics from PRP-loaded chitosan scaffolds for tissue engineering applications. Flow cytometry analysis showed that centrifugation processes used for PRP preparation did not cause significant effect on platelet activation levels by means of markers investigated. Two different methods were used to prepare PRP-loaded chitosan scaffolds: (i) PRP was added to chitosan gel before freeze-drying to prepare scaffolds called as "GEL" and (ii) PRP was embedded to freeze-dried chitosan scaffolds to prepare scaffolds called as "SPONGE." In addition, nonactivated PRP and PRP activated with type-I collagen were used as control groups. Scanning electron microscopy images demonstrated that, in GEL group, there is no deterioration on the scaffolds porous, 3D, and interconnected structure. GF release kinetics was determined by enzyme-linked immunosorbent assay for platelet-derived GF-BB, transforming GF-β1, and insulin-like GF-1. A sustained release of GFs was achieved in GEL group while a sharp burst release was observed for all the GFs from the SPONGE groups. Moreover, platelet-derived GF-BB, insulin-like GF-1, and transforming GF-β1 releases were prolonged to 20 days in GEL groups, and the biological activities of all GFs released from GEL and SPONGE scaffolds were preserved. This study demonstrated that chitosan scaffold that was called GEL could be an appropriate carrier for PRP applications by providing sustained release of GFs.

Evaluation of healing processes of intraosseous defects with and without guided bone regeneration and platelet rich plasma. An animal study

BACKGROUND

In most cases, the natural healing of intrabony defects only leads to restoration of tissue continuity without differentiation and function. However, repair is not regarded to be an optimal treatment method, as confirmed in many clinical cases. Thus it is important to choose a surgical procedure which makes it possible to achieve restitution ad integrum of the bone structure. The choice of the GBR technique is crucial, in terms of the clinical conditions and limitations resulting from the use of a particular material.

OBJECTIVE

The objective of this study has been the analysis of effectiveness of selected surgical treatment techniques of intrabony defects in rabbits.

MATERIALS AND METHODS

Research was conducted on 36 white rabbits. The operation technique was a criterion of division into 3 groups: BG/BOC (Bio-Oss Collagen(®)+Bio-Gide Perio(®)), BOC/PRP (Bio-Oss Collagen(®)+PRP), C (control group). Qualitative and quantitative histopathological evaluation was carried out after 1, 3, 6 and 12 months.

RESULTS

The highest value of the bone surface area 31.9% (SD 1.8) was achieved in BOC/BG group three months after the implantation, while the lowest was revealed in C - group - 12.5% (SD 1.32) one month following the procedure.

CONCLUSIONS

Upon quantitative histological assessment, the bone tissue presented the most intensive osteogenesis within one month from the application of BOC/PRP, whereas this was observed after the application of BOC/BG in later stages. The application of two regenerative methods influenced the rate, quality and overall treatment of intraosseus defects.

Platelet rich plasma. A new treatment tool for the rheumatologist?

Platelet Rich Plasma (PRP) is a novel therapeutic tool that has revolutionized the world of sports medicine and trauma due to therapeutic success shown in the media. Subject to ongoing debate, the PRP is outlined along a spectrum of musculoskeletal therapies with many qualities that make it ideal for use in the rheumatology: effectiveness, safety, easy handling and low cost. Is PRP a product of marketing? Or, conversely, is an interesting tool to consider in the armamentarium of the rheumatologist. In the following review we will analyze in detail its principles, preparation, and management regimes. We will reflect on potential adverse effects and, finally, there will be a critical analysis of the scientific evidence that supports its potential use in the rheumatology clinic.

Histological evaluation of bone healing using organic bovine bone in combination with platelet-rich plasma (an experimental study on rabbits)

OBJECTIVES

This study was carried out to histologically assess the effect of bone grafting materials extracted from bovine origin on the bone healing process either alone or when mixed with autologous platelet-rich plasma which could be used in many procedures of oral and maxillofacial bone and implant reconstructive surgery.

MATERIALS AND METHODS

Sixteen rabbits were used; three intrabony defects in the femur bone of each rabbit were created, one left unfilled for normal healing process and served as control, the second filled with xenogenic graft (Gen-Ox-lyophilized bovine bone organic matrix), and the third filled with (Gen-Ox-lyophilized bovine bone organic matrix) mixed with autologous platelet-rich plasma. Histological examination of the sections was performed after staining with H&E and Van Geison stains. The histomorphometric analysis including counting of bone cells (osteoblasts, osteocytes, and osteoclasts) with performance of osteon diameter and lamellar thickness at the end of the fourth week postoperatively was obtained.

RESULTS

It has been shown that with the use of autologous platelet-rich plasma in combination with the xenogenic bone graft prepared from bovine origin, new bone formation and neovascularization were enhanced significantly when compared with xenogenic graft alone.

CONCLUSION

The addition of PRP to xenogenic bone substitute in small bone defects of the rabbit femur showed a histomorphometric increase in bone formation (at the fourth week of healing).

CLINICAL RELEVANCE

Platelet concentrate might be used to accelerate the osseointegration of enosseous dental implants.

Bovine Anorganic Bone Graft Associated with Platelet-Rich Plasma: Histologic Analysis in Rabbit Calvaria

Autogenous bone tissue has regeneration potential; however, this capacity may not be sufficient in larger bone defects. The aim of this study is to histologically evaluate anorganic bovine bone grafts (GenOx Inorg) with or without platelet-rich plasma (PRP). Two bone lesions were created in calvaria of 12 rabbits. The 24 surgical lesions were separated into 3 groups: coagulous, anorganic, and anorganic with PRP. At the 4-week time point, the animals were euthanized and the grafted area removed, fixed in formalin 10% with phosphate buffered saline, 0.1 M, and embedded in paraffin. The histologic parameters analyzed were new bone filling the defect area, presence of giant cells and particles of the graft, and new bone formation associated with the particles. In the coagulous group, defects were filled with fibrous tissue that attached the periosteum and little bone neoformation in the periphery. In anorganic groups with or without PRP, little new bone formation in the periphery of the defect was observed; however, in the center of some defects there was new bone. Moderate presence of giant cells and little new bone formation was associated with the innumerous graft particles. Histologic results revealed no statistically significant differences among the defects new bone fill between the studied groups (P  =  .64). There was no significant difference in the number of giant cells (P  =  .60), graft particles (P  =  .46), and new bone formation around graft particles (P  =  .26), whether PRP was added or not. Anorganic bone, isolated or mixed with PRP, was biocompatible and osteoconductive, while maintaining bone volume.

Musculoskeletal applications of platelet-rich plasma: fad or future?

OBJECTIVE

The purpose of this article is to detail the biology of platelet-rich plasma (PRP), critically review the existing literature, and discuss future research applications needed to adopt PRP as a mainstay treatment method for common musculoskeletal injuries.

CONCLUSION

Any promising minimally invasive therapy such as PRP deserves further investigation to avoid surgery. Diagnostic imaging outcome assessments, including ultrasound-guided needle precision, should be included in future investigations.

Effects of a highly concentrated platelet-rich plasma on the bone repair using non-critical defects in the calvaria of rabbits

PURPOSE

To verify the effect of highly concentrated platelet-rich plasma (hPRP) in the pathways of bone repair using non-critical defects in the calvaria of rabbits.

METHODS

The hPRP was produced from collected venous blood of 21 rabbits. Four non-critical defects of 8 mm in diameter were created on the calvaria of each animal. The defects were all treated differently: autogenous particled bone (APB, group 1), autogenous particled bone associated with hPRP (APB + hPRP, group 2), isolated hPRP (group 3), and blood clot (control, group 4). Animals were submitted to euthanasia on the 2nd, 4th and 6th week postoperatively. Histological and histomorphometric analysis were carried through.

RESULTS

After two weeks, groups 1 and 2 were in more advanced stage of repair than 3 and 4. At this period, comparing the groups 1 and 2, no significant differences were found between both, which also happened between the groups 3 and 4. However, after four and six weeks, the group 1 showed a more advanced stage of repair among all the other studied groups, while group 2 was in more advanced signs of bone repair than groups 3 and 4. Comparing groups 3 and 4, after four and six weeks, the least advanced stage of bone repair was found to be within group 3.

CONCLUSION

The use of a highly concentrated PRP was considered prejudicial to the repair of non-critical defects in the calvaria of rabbits, either in the association of autogenous particled bone, when compared to autogenous particled bone alone, or in its isolated form, when compared to blood clot (control).

Uncultured marrow mononuclear cells delivered within fibrin glue hydrogels to porous scaffolds enhance bone regeneration within critical-sized rat cranial defects

For bone tissue engineering, the benefits of incorporating mesenchymal stem cells (MSCs) into porous scaffolds are well established. There is, however, little consensus on the effects of or need for MSC handling ex vivo. Culture and expansion of MSCs adds length and cost, and likely increases risk associated with treatment. We evaluated the effect of using uncultured bone marrow mononuclear cells (bmMNCs) encapsulated within fibrin glue hydrogels and seeded into porous scaffolds to regenerate bone over 12 weeks in an 8-mm-diameter, critical-sized rat cranial defect. A full factorial experimental design was used to evaluate bone formation within model poly(L-lactic acid) and corraline hydroxyapatite scaffolds with or without platelet-rich plasma (PRP) and bmMNCs. Mechanical push-out testing, microcomputed tomographical analyses, and histology were performed. PRP showed no benefit for bone formation. Cell-laden poly(L-lactic acid) scaffolds without PRP required significantly greater force to displace from surrounding tissues than control (cell-free) scaffolds, but no differences were observed during push-out testing of coral scaffolds. For bone volume formation as analyzed by microcomputed tomography, significant positive overall effects were observed with bmMNC incorporation. These data suggest that bmMNCs may provide therapeutic advantages in bone tissue engineering applications without the need for culture, expansion, and purification.

Effects of platelet-rich plasma and chitosan combination on bone regeneration in experimental rabbit cranial defects

This study aimed to investigate and compare the effect of chitosan sponge and platelet-rich plasma (PRP) gel alone as well as their combination on bone regeneration in rabbit cranial defects. Four cranial defects with a 4.5-mm diameter were created in rabbit cranium and grafted with PRP, chitosan sponge alone, and chitosan sponge incorporated with PRP. The rabbits were killed by the fourth and eighth weeks, and the defects were analyzed histologically. Higher bone formation was observed in the PRP group when compared with the other groups at weeks 4 and 8. All parts of the defects were filled with thick trabecular new bone in the PRP group. The amount of new bone formation in the control groups was found to be less when compared with the PRP group and the least in the chitosan group. The defects that were filled with chitosan sponge showed a limited amount of new bone formation and an obvious fibrous demarcation line between chitosan particles and bone. Application of PRP showed a histological tendency toward increased bone formation. Other forms or derivatives of chitosan may have beneficial effects to achieve new bone regeneration.

A review on endogenous regenerative technology in periodontal regenerative medicine

Periodontitis is a globally prevalent inflammatory disease that causes the destruction of the tooth-supporting apparatus and potentially leads to tooth loss. Currently, the methods to reconstitute lost periodontal structures (i.e. alveolar bone, periodontal ligament, and root cementum) have relied on conventional mechanical, anti-infective modalities followed by a range of regenerative procedures such as guided tissue regeneration, the use of bone replacement grafts and exogenous growth factors (GFs), and recently developed tissue engineering technologies. However, all current or emerging paradigms have either been shown to have limited and variable outcomes or have yet to be developed for clinical use. To accelerate clinical translation, there is an ongoing need to develop therapeutics based on endogenous regenerative technology (ERT), which can stimulate latent self-repair mechanisms in patients and harness the host's innate capacity for regeneration. ERT in periodontics applies the patient's own regenerative 'tools', i.e. patient-derived GFs and fibrin scaffolds, sometimes in association with commercialized products (e.g. Emdogain and Bio-Oss), to create a material niche in an injured site where the progenitor/stem cells from neighboring tissues can be recruited for in situ periodontal regeneration. The choice of materials and the design of implantable devices influence therapeutic potential and the number and invasiveness of the associated clinical procedures. The interplay and optimization of each niche component involved in ERT are particularly important to comprehend how to make the desired cell response safe and effective for therapeutics. In this review, the emerging opportunities and challenges of ERT that avoid the ex vivo culture of autologous cells are addressed in the context of new approaches for engineering or regeneration of functional periodontal tissues by exploiting the use of platelet-rich products and its associated formulations as key endogenous resources for future clinical management of periodontal tissue defects.

Platelet-rich plasma diminishes calvarial bone repair associated with alterations in collagen matrix composition and elevated CD34+ cell prevalence

The interaction between platelets and both type I and III collagens plays an important role in modulating platelet adhesion and aggregation, also contributing to the chemotaxis of CD34+ cells. The interaction with type III collagen can maintain high levels of collagen and alter the biology of bone repair when the PRP is used. The aim of this study was to evaluate the effect of platelet-rich plasma (PRP) and autograft on the presence of type III and type I collagens, the ratio between them, as well as the presence of CD34+ progenitor cells, while comparing these results by means of a histomorphometric analysis of the bone tissue. Four bone defects (8.0mm in diameter and 2.0mm in depth) were produced on the calvarium of 23 rabbits. The surgical defects were treated with either autogenous bone grafts, autogenous bone grafts with PRP and PRP alone. Animals were euthanized at 2, 4 or 6 weeks post-surgery. Histological, histomorphometric and immunohistochemical analyses were performed to assess repair time, as well as the expression of type I and III collagens, and number of progenitor CD34+ cells. Data were analyzed using the ANOVA and Student-Newman-Keuls test (alpha=5%). An enlarged granulation and medullary tissue areas in the PRP groups were observed. The use of PRP in this study hindered bone deposition, also enhanced type III to type I collagen ratio and the chemotaxis of CD34+ progenitor cells, similarly to a thrombogenic effect.

Bone quality: a reality for the process of osseointegration

This article subscribes to the initial condition of bone quality and its ultimate effect on the success of dental implant treatment. A high success rate for the preservation of the alveolar bone around oral implants is predicated on good bone quality. For implantologists, the classification of bone quality should be based on the key elements required for osseointegration. These include structural morphology and cellular characteristics such as monocytes/macrophages, mesenchymal progenitor cells, fibroblasts, osteoclasts, and cells associated with angiogenesis.

Bone and wound healing augmentation with platelet-rich plasma

Over the past two decades, autologous platelets that have been sequestered, concentrated, and mixed with thrombin to generate growth factor-concentrated platelet-rich plasma for application to bone and wounds to aide healing have been a subject of great interest. This article reviews the literature related to the use of autologous platelet-rich plasma in bone and wound healing, and reviews the processes necessary to secure a high concentration of viable platelets. Although not yet definitive, autologous platelet-rich plasma has been shown to be safe, reproducible, and effective in mimicking the natural process of bone and wound healing.

Platelet-poor plasma stimulates the proliferation but inhibits the differentiation of rat osteoblastic cells in vitro

INTRODUCTION

Recent studies have shown that the use of platelet preparations in bone and implant surgery might stimulate bone formation. However, the biological mechanisms are not well understood. Moreover, few studies have attempted to evaluate the effect of platelet-poor plasma (PPP), which is a product of the platelet-rich plasma preparation process.

OBJECTIVE

Thus, this study investigated the behavior of osteoblasts isolated from fetal rat calvaria cultivated in the presence of homologous PPP.

MATERIAL AND METHODS

PPP was obtained by centrifugation of the rat mother's blood and used in replacement of fetal calf serum, which is classically used in primary culture procedures. Proliferation was measured by an MTT assay at 24, 48, and 72 h. Real-time PCR was performed to study the expression of Runx2, Dlx5, and osteocalcin (OC) on days 0 (4 h), 1, 3, 7, and 12.

RESULTS

Alkaline phosphatase (ALP) biochemical activity was evaluated on days 0 (4 h), 1, 3, 7, and 12. Observations by phase-contrast microscopy showed that osteoblasts were able to differentiate until the mineralization of the matrix in the presence of PPP. PPP enhanced the proliferation significantly compared with the control group (P< or =0.001). PCR results showed that Runx2, Dlx5, and OC were expressed by cells in the experimental group at lower levels compared with the control group. Biochemical assay of ALP showed a lower activity in the experimental group compared with the control group (P<0.001).

CONCLUSION

These results suggest that, in the presence of homologous PPP, rat osteoblastic cells are able to maintain their phenotype, with a higher rate of proliferation. However, PPP seems to inhibit osteoblastic differentiation.

The biology of platelet-rich plasma and its application in oral surgery: literature review

Platelet-rich plasma (PRP) is a new approach in tissue regeneration and a developing area for clinicians and researchers. It is used in various surgical fields, including oral and maxillofacial surgery. PRP is prepared from the patient's own blood and contains growth factors that influence wound healing. Of these growth factors, platelet-derived growth factor, transforming growth factor, insulin-like growth factor, and epidermal growth factor play a pivotal role in tissue repair mechanisms. Although the growth factors and mechanisms involved are still poorly understood, the easy application of PRP in the clinic and its possible beneficial outcome, including reduction of bleeding, rapid soft tissue healing, and bone regeneration, hold promise for new treatment approaches. However, animal studies and human trials demonstrate conflicting results regarding the application of PRP. Therefore the aim of this literature review is to evaluate the scientific evidence regarding the use of PRP in dentistry, to describe the different bioactive substances included in PRP and their participation in the healing process, to elucidate the different techniques and available technology for PRP preparation, to review animal and human studies, to clarify risks, and to provide guidance for future research.

The biology of platelet-rich plasma and its application in trauma and orthopaedic surgery: a review of the literature

Although mechanical stabilisation has been a hallmark of orthopaedic surgical management, orthobiologics are now playing an increasing role. Platelet-rich plasma (PRP) is a volume of plasma fraction of autologous blood having platelet concentrations above baseline. The platelet alpha granules are rich in growth factors that play an essential role in tissue healing, such as transforming growth factor-beta, vascular endothelial growth factor, and platelet-derived growth factor. PRP is used in various surgical fields to enhance bone and soft-tissue healing by placing supraphysiological concentrations of autologous platelets at the site of tissue damage. The easily obtainable PRP and its possible beneficial outcome hold promise for new regenerative treatment approaches. The aim of this literature review was to describe the bioactivities of PRP, to elucidate the different techniques for PRP preparation, to review animal and human studies, to evaluate the evidence regarding the use of PRP in trauma and orthopaedic surgery, to clarify risks, and to provide guidance for future research.

Injectable tissue-engineered bone composed of human adipose-derived stromal cells and platelet-rich plasma

This study aimed to evaluate the effects of human platelet-rich plasma (hPRP) on the proliferation and osteogenic differentiation of human adipose-derived stromal cells (hADSCs) and to construct a novel injectable tissue-engineered bone (ITB) composed of hPRP and hADSCs. hADSCs were isolated from liposuction tissues of healthy patients. hPRP was obtained by traditional two-step centrifugation. MTT, alkaline phosphatase (ALP) activity and mineralization assays were used to evaluate the effects of different concentrations of hPRP on cell proliferation and osteogenic differentiation in vitro. hADSCs cultured in optimal concentration of activated hPRP were subcutaneously injected into the inguinal groove of nude mice with hPRP and thrombin. X-ray, H&E staining and immunohistochemical analysis were used to examine the bone formation. Studies in vitro revealed that cell proliferation, ALP activity and mineralization were induced by hPRP and 10-12.5% of hPRP seemed to be the optimal concentration. Studies in vivo showed that this ITB formed bone structure in heterotopic site of nude mice. These findings indicate that the ITB composed of hPRP and hADSCs may represent a prologue for the development of a novel biological solution to bone defect. However, further investigations should be done to fully reveal the characteristics of this ITB.

Sinus floor elevation using autogenous bone or bone substitute combined with platelet-rich plasma

OBJECTIVE

Sinus augmentation is a common approach for patients with severe alveolar ridge atrophy. However, autogenous bone sometimes results in donor site complications. Bone substitutes with platelet-rich plasma (PRP) promote early bone formation with autogenous bone. Use of PRP on autogenous bone and a bovine bone substitute were investigated in this split-mouth animal study.

STUDY DESIGN

Premolars were extracted from minipigs. Each animal received sinus augmentation using a lateral approach with simultaneous insertion of 3 implants in each site. Groups were randomized using autogenous bone alone and combined with PRP or a bovine hydroxyapatite alone in combination with PRP.

RESULTS

Microradiographic findings in the autogenous group did not show significantly different rates by using autogenous bone alone or combined with PRP. Using the bovine hydroxyapatite as augmentation material only at 8 weeks, a nonsignificant effect in the PRP group could be seen. At all other observation periods, no significant influence was observed.

CONCLUSION

No significant influence of PRP was found.

The effect of different platelet-rich plasma concentrations on proliferation and differentiation of human periodontal ligament cells in vitro

OBJECTIVES

The use of platelets and platelet products has become increasingly popular clinically as a means of accelerating endosseous wound healing. It is likely that growth factors released by activated platelets at the site of injury play a role in periodontal regeneration by regulating cellular activity. The purpose of this study was to evaluate the biological effects of platelet-rich plasma (PRP) on human periodontal ligament cells (hPDLCs) in vitro.

MATERIALS AND METHODS

Primary cultures of hPDLCs were obtained from healthy premolars. PRP was isolated by two-step centrifugation. Two main growth factors present in the thrombin-activated PRP (platelet-derived growth factor [PDGF-AB] and transforming growth factor-beta1 [TGF-beta1]) were evaluated using ELISA assay. Activated PRP or the combination of recombined human TGF-beta1 (rhTGF-beta1) and PDGF-AB (rhPDGF-AB) were added to hPDLCs in different concentrations to assess cell proliferation and osteogenic differentiation.

RESULTS

PRP contained high levels of TGF-beta1 and PDGF-AB. Cell attachment, proliferation and ALP activity were enhanced by addition of PRP or rhTGF-beta1 and rhPDGF-AB combination to the cell cultures, while the stimulatory potency of PRP was much greater than the latter. These stimulatory effects presented in a dose-dependant manner, it seemed that PRP with 50~100 ng/ml TGF-beta1 was an ideal concentration.

CONCLUSIONS

PRP can enhance hPDLC adhesion, proliferation and induce the differentiation of hPDLC into mineralized tissue formation cell; thereby contribute to the main processes of periodontal tissue regeneration. For economical and biological reasons, PRP has more clinical beneficial than analogous growth factors.