Platelet-rich plasma inhibits demineralized bone matrix-induced bone formation in nude mice

Effects of Combination of BMP7, PFG, and Autograft on Healing of the Experimental Critical Radial Bone Defect by Induced Membrane (Masquelet) Technique in Rabbit

Background

Healing of large segmental bone defects can be challenging for orthopedic surgeons. This research was conducted to provide further insight into the effects of BMP7 in combination with autograft and platelet fibrin glue (PFG) on bone regeneration by Masquelet technique (MT).

Methods

Twenty five domestic male rabbits, more than 6 months old, weighing 2.00±0.25 kg were randomly divided into five equal groups as follows: MT-blank cavity (without any biological or synthetic materials) (1), blank cavity (2), MT-autograft (3), MT-autograft-BMP7 (4), and MT-BMP7-PFG (5). A 20 mm segmental defect was made in radial bone in both forelimbs. The Masquelet technique was done in all groups except group 2. The study was evaluated by radiology, biomechanics, histopathology and scanning electron microscopy.

Results

The results showed that Masquelet technique enhanced the healing process, as, the structural and functional criteria of the injured bone showed significantly improved bone healing (P<0.05). Treatment by PFG-BMP7, Autograft-BMP7, and autograft demonstrated beneficial effects on bone healing. However, Autograft-BMP7 was more effective than autograft in healing of the radial defect in rabbits.

Conclusion

Our findings introduce the osteogenic materials in combination with Masquelet technique as an alternative for reconstruction of the big diaphyseal defects in the long bones in animal models. Our findings may be useful for clinical application in future.

Platelet-rich plasma and regenerative dentistry

Regenerative dentistry is an emerging field of medicine involving stem cell technology, tissue engineering and dental science. It exploits biological mechanisms to regenerate damaged oral tissues and restore their functions. Platelet‐rich plasma (PRP) is a biological product that is defined as the portion of plasma fraction of autologous blood with a platelet concentration above that of the original whole blood. A super‐mixture of key cytokines and growth factors is present in platelet granules. Thus, the application of PRP has gained unprecedented attention in regenerative medicine. The rationale underlies the utilization of PRP is that it acts as a biomaterial to deliver critical growth factors and cytokines from platelet granules to the targeted area, thus promoting regeneration in a variety of tissues. Based on enhanced understanding of cell signalling and growth factor biology, researchers have begun to use PRP treatment as a novel method to regenerate damaged tissues, including liver, bone, cartilage, tendon and dental pulp. To enable better understanding of the regenerative effects of PRP in dentistry, this review describes different methods of preparation and application of this biological product, and provides detailed explanations of the controversies and future prospects related to the use of PRP in dental regenerative medicine.

Innovative Biomaterials for Bone Regrowth

The regenerative medicine, a new discipline that merges biological sciences and the fundamental of engineering to develop biological substitutes, has greatly benefited from recent advances in the material engineering and the role of stem cells in tissue regeneration. Regenerative medicine strategies, involving the combination of biomaterials/scaffolds, cells, and bioactive agents, have been of great interest especially for the repair of damaged bone and bone regrowth. In the last few years, the life expectancy of our population has progressively increased. Aging has highlighted the need for intervention on human bone with biocompatible materials that show high performance for the regeneration of the bone, efficiently and in a short time. In this review, the different aspects of tissue engineering applied to bone engineering were taken into consideration. The first part of this review introduces the bone cellular biology/molecular genetics. Data on biomaterials, stem cells, and specific growth factors for the bone regrowth are reported in this review.

Healing potential of nanohydroxyapatite, gelatin, and fibrin-platelet glue combination as tissue engineered scaffolds in radial bone defects of rats

Different biomaterials have been used in orthopedic surgery. Evaluation of biomaterials for bone healing promotion has been a wide area of research of the orthopedic field. Sixty critical size defects of 5 mm long were bilaterally created in the radial diaphysis of 30 rats. The animals were randomly divided into six equal groups as empty defect, autograft, nanohydroxyapatite (nHA), Gelatin (Gel)-nHA, fibrin-platelet glue (FPG)-nHA, and Gel-FPG-nHA groups (n = 10 in each group). Radiographs of each forelimb were taken postoperatively on the 1st day and then at the 28th and 56th days post injury. After 56 days, the rats were euthanized and their harvested healing bone samples were evaluated by histopathology, scanning electron microscopy, and biomechanical testing. All the treated defects demonstrated significantly superior new bone formation, remodeling, and bone tissue volume. Moreover, the defects treated with FPG-nHA showed significantly higher ultimate load, yield load, and stiffness. The Gel-FPG-nHA moderately improved bone regeneration that was not close to the autograft in some parameters, whereas FPG-nHA significantly improved bone healing closely comparable with the autograft group in most parameters. In conclusion, although all the nHA-containing scaffolds had some beneficial effects on bone regeneration, the FPG-nHA scaffold was more effective in improving the structural and functional properties of the newly formed bone and was more osteoinductive than the Gel and was comparable to the autograft. Therefore, the FPG can be regarded as a promising option to be used in conjunction with mineral scaffolds for bone tissue engineering.

Blood derivatives awaken in regenerative medicine strategies to modulate wound healing

Blood components play key roles in the modulation of the wound healing process and, together with the provisional fibrin matrix ability to selectively bind bioactive molecules and control its spatial-temporal presentation, define the complex microenvironment that characterize this biological process. As a biomimetic approach, the use of blood derivatives in regenerative strategies has awakened as a source of multiple therapeutic biomolecules. Nevertheless, and despite their clinical relevance, blood derivatives have been showing inconsistent therapeutic results due to several factors, including proper control over their delivery mechanisms. Herein, we highlight recent trends on the use biomaterials to protect, sequester and deliver these pools of biomolecules in tissue engineering and regenerative medicine approaches. Particular emphasis is given to strategies that enable to control their spatiotemporal delivery and improve the selectivity of presentation profiles of the biomolecules derived from blood derivatives rich in platelets. Finally, we discussed possible directions for biomaterials design to potentiate the aimed regenerative effects of blood derivatives and achieve efficient therapies.

The effects of gelatin, fibrin-platelet glue and their combination on healing of the experimental critical bone defect in a rat model: radiological, histological, scanning ultrastructural and biomechanical evaluation

Fibrin-platelet glue (FPG) is a blood derivative, in which platelets and fibrinogen are concentrated in a small plasma volume, by differential centrifugation and precipitation. It can form a three-dimensional and biocompatible fibrin scaffold with a myriad of growth factors and proteins that are released progressively to the local environment and contribute to the accelerated postoperative bone healing. Gelatin (Gel) is a derivative of collagen and can promote cell adhesion and proliferation due to its unique sequence of amino acids, so it is suitable for bone tissue applications. This study examined the effects of Gel, FPG and their combinations as bone scaffold on the healing of surgically created critical-size defects in rat radius. Fifty critical size defects of 5 mm long were bilaterally created in the radial diaphysis of 25 rats. The animals were randomly divided into five equal groups as empty defect, autograft, Gel, FPG and Gel-FPG groups (n = 10 in each group). Radiographs of each forelimb were taken postoperatively on the 1st day and then at the 28th and 56th days post injury to evaluate bone formation, union and remodeling of the defect. After 56 days, the rats were euthanized and their harvested healing bone samples were evaluated by histopathology, scanning electron microscopy (SEM) and biomechanical testing. The results of present study showed that the Gel alone did not significantly affect bone healing and regeneration; however, the Gel treated defects promoted healing more than those that were left untreated (negative control). Furthermore, the FPG-enhanced grafts provided a good scaffold containing numerous growth factors for proliferation of osteoinduction and was effective in improving the structural and functional properties of the newly formed bone more than that of the untreated and also the Gel treated groups. Incorporation of Gel into the FPG scaffold improved healing potential of the FPG scaffold; however, it was still inferior to the autograft (positive control). Although the Gel-FPG scaffolds had best effectiveness during bone regeneration, it still needs to be further enhanced by incorporation of the ceramic and osteoinductive biomaterials.

Bone grafts and biomaterials substitutes for bone defect repair: A review

Bone grafts have been predominated used to treat bone defects, delayed union or non-union, and spinal fusion in orthopaedic clinically for a period of time, despite the emergency of synthetic bone graft substitutes. Nevertheless, the integration of allogeneic grafts and synthetic substitutes with host bone was found jeopardized in long-term follow-up studies. Hence, the enhancement of osteointegration of these grafts and substitutes with host bone is considerably important. To address this problem, addition of various growth factors, such as bone morphogenetic proteins (BMPs), parathyroid hormone (PTH) and platelet rich plasma (PRP), into structural allografts and synthetic substitutes have been considered. Although clinical applications of these factors have exhibited good bone formation, their further application was limited due to high cost and potential adverse side effects. Alternatively, bioinorganic ions such as magnesium, strontium and zinc are considered as alternative of osteogenic biological factors. Hence, this paper aims to review the currently available bone grafts and bone substitutes as well as the biological and bio-inorganic factors for the treatments of bone defect.

EFFECT OF PLATELET RICH PLASMA (PRP) TO AUTOGENOUS BONE GRAFT

Bone graft use in maxillofacial surgery is currently developing, though some problems still persist. One of promising solutions to the problems is application of platelet rich plasma which may accelerate soft tissue healing and bone formation. This study aims to provide basic understanding to the development of PRP application in bone healing where bone graft is applied on human maxillae. Bone defects were made on maxillae of albino rabbits, with an application of bone graft in control group and bone graft plus PRP in treatment group. Histopathological analysis was performed in both groups to assess osteoblast density and collagen tissue area. On day 21st, more osteoblast density and collagen area in treatment group are significantly observed (p<0.05, 95% confidence interval). Observations were made on hard callus formation. In conclusions, platelet rich plasma may increase density of osteoblast in rabbit maxillary bone graft.

A bioresorbable polylactide implant used in bone cyst filling

The aims in treating patients diagnosed with critical-sized bone defects resulting from bone cysts are to replace the lost bone mass after its removal and to restore function. The standard treatment is autologous or allogeneic bone transplantation, notwithstanding the known consequences and risks due to possible bone infection, donor site morbidity, bleeding and nerve injury and possible undesirable immune reactions. Additionally, allogeneic grafts are inhomogeneous, with a mosaic of components with difficult-to-predict regenerative potential, because they consist of cancellous bone obtained from different bones from various cadavers. In the present study, a 22-year-old patient with a history of right humerus fracture due to bone cysts was diagnosed with recurrent cystic lesions based on X-ray results. The patient qualified for an experimental program, in which he was treated with the application of a bioresorbable polylactide hybrid sponge filled with autologous platelet-rich plasma. Computed tomography and magnetic resonance imaging performed 3, 6, and 36 months after surgery showed progressive ossification and bone formation inside the defect cavity in the humerus. Three years after treatment with the bone substitute, the patient is pain free, and the cystic lesions have not reoccurred.

Osteoinductive potential of 4 commonly employed bone grafts

OBJECTIVES

Guided bone regeneration (GBR) aims to predictably restore missing bone that has been lost due to trauma, periodontal disease or a variety of systemic conditions. Critical to this procedure is the ability of a bone grafting material to predictably serve as a 3-dimensional scaffold capable of inducing cell and bone tissue in-growth at the material surface. Although all bone grafts are osteoconductive to bone-forming osteoblasts, only a small number of commercially available bone grafts with FDA approval are osteoinductive including demineralized freeze-dried bone allographs (DFDBA) and scaffolds containing bone morphogenetic proteins (BMPs). Recently, a class of synthetic bone grafts fabricated from biphasic calcium phosphate (BCP) sintered at a low temperature have been shown to form ectopic bone formation in non-skeletal sites without the use of growth factors. Therefore, the present study aimed to compare the osteoinductive potential of this group of synthetic BCP alloplasts with autografts, allografts and xenografts.

MATERIALS AND METHODS

In the present study, 4 types of bone grafting materials including autogenous bone harvested with a bone mill, DFDBA (LifeNet, USA), a xenograft derived from bovine bone mineral (NBM, BioOss, Geistlich, Switzerland) and a novel synthetic biphasic calcium phosphate (BCP, Straumman, Switzerland) were implanted into intramuscular pouches of 24 rats and analysed histologically for their ability to form ectopic bone formation around grafting particles. A semi-quantitative osteoinductive score was used to quantify the osteoinductive ability of each bone graft.

RESULTS

The results from the present study reveal that (1) autogenous bone resorbed rapidly in vivo, (2) the xenograft showed no potential to form ectopic bone formation and (3) both DFDBA and BCP were able to stimulate ectopic bone formation.

CONCLUSION

These studies demonstrate that these newly developed synthetic bone grafts have potential for inducing ectopic bone formation similar to DFDBA. Future clinical testing is necessary to reveal their bone-inducing properties in clinical scenarios including GBR procedures and in combination with implant dentistry.

CLINICAL RELEVANCE

Novel BCP scaffolds are able to induce ectopic bone formation without the use of osteoinductive growth factors such as BMP2 and thus demonstrate a large clinical possibility to further enhance bone formation for a variety of clinical procedures.

Pulp Revascularization on Permanent Teeth with Open Apices in a Middle-aged Patient

Pulp revascularization is a promising procedure for the treatment of adolescents' immature permanent teeth with necrotic pulp and/or apical periodontitis. However, the ability to successfully perform pulp revascularization in a middle-aged patient remains unclear. A 39-year-old woman was referred for treatment of teeth #20 and #29 with necrotic pulp, extensive periapical radiolucencies, and incomplete apices. Pulp revascularization procedures were attempted, including root canal debridement, triple antibiotic paste medication, and platelet-rich plasma transplantation to act as a scaffold. Periapical radiographic and cone-beam computed tomographic examinations were used to review the changes in the apical lesions and root apex configuration. The patient remained asymptomatic throughout the 30-month follow-up. Periapical radiographic examination revealed no change in the apical lesions of either tooth at 8 months. The periapical radiolucency disappeared on tooth #20 and significantly decreased on tooth #29 by the 30-month follow-up, findings that were also confirmed by cone-beam computed tomographic imaging. No evidence of root lengthening or thickening was observed. Successful revascularization was achieved in a middle-aged patient's teeth.

Platelet-rich plasma for enhancing surgical rotator cuff repair: evaluation and comparison of two application methods in a rat model

PURPOSE

Platelet-rich plasma (PRP) is a natural concentrate of autologous growth factors now being widely tested in different fields of medicine for its potential in enhancing the regeneration of tissue with low healing potential. However, studies of PRP in enhancing rotator cuff repair have been contradictory, perhaps because of how PRP is administered. The purpose of this study is to evaluate the effect of PRP and compare two different application methods of PRP on rotator cuff healing.

METHODS

The supraspinatus tendons of 48 mature, male Wistar-Albino rats were detached from their insertion on the humerus. The animals were divided into four groups: (1) no repair, (2) primary repair, (3) repair plus PRP injections into the tendon-bone interface, and (4) repair plus PRP absorbed from a sponge carrier to the tendon-bone interface. The tendons were evaluated biomechanically and histologically at week 8.

RESULTS

Cuffs repaired with PRP had significantly greater mean (SD) load-to-failure rates [11.1 (6.5) and 11.6 (3.9) N; P < 0.05] and stiffness [3.5 (2.3) and 1.6 (0.75) N; P < 0.05] than did cuffs repaired without PRP. The groups receiving PRP did not differ significantly on these variables. Histological evaluation showed no significant differences among the four groups.

CONCLUSIONS

The application of PRP, independent of the application method, significantly improved biomechanical properties at the rotator cuff tendon-bone interface. The type of application, injection or absorption from a sponge did not influence the effect of PRP on rotator cuff healing.

Demineralized bone matrix in extraction sockets: a clinical and histologic case series

PURPOSE

To evaluate its efficacy and predictability in immediate extraction sockets, this case series used demineralized bone matrix in a puttylike carrier (DBM putty) with and without mineralized bone chips. Each preparation was made from the long bones of the same tissue donor; the only excipient material was water.

MATERIAL AND METHODS

A single failing tooth was atraumatically extracted from each study subject, and the socket was debrided. Intact sockets were grafted with DBM putty (n = 6), and sockets with buccal defects were grafted with DBM putty with bone chips (n = 6). A bovine pericardium membrane was draped over the graft site, and tension-free primary closure was obtained. After 6 months of healing, a trephine biopsy was taken from the center of each graft, and then, a dental implant was placed. Two subjects were withdrawn, and histologic data could not be obtained from 2 other patients.

RESULTS

Mean new bone fill was 40.28% for DBM putty (n = 5) and 44.60% for DBM putty with bone chips (n = 4).

CONCLUSIONS

Both preparations maintained ridge dimensions and, despite ongoing bone turnover, produced adequate mineralized tissue that enabled implant placement at 6 months. This finding warrants further research.

Demineralized bone matrix and platelet-rich plasma do not improve healing of osteochondral defects of the talus: an experimental goat study

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of demineralized bone matrix (DBM) with and without platelet-rich plasma (PRP) in the treatment of osteochondral defects (OCDs) of the talus. We hypothesized that treatment with DBM would result in more bone formation than no treatment in control OCDs, and that PRP would further enhance the regenerative capacity of DBM.

METHOD

A standardized 6-mm OCD was created in each talus of 16 adult goats. According to a randomization scheme, one OCD of each goat was treated with allogeneic DBM hydrated with normal saline (n = 8) or hydrated with autologous PRP (n = 8). The contralateral OCD (n = 16) served as control. After 24 weeks, the animals were euthanized and the tali excised. Various outcome parameters were analyzed with use of macroscopic evaluation, micro-computed tomography (μCT), histology, histomorphometry, and fluorescence microscopy.

RESULTS

None of the analyses revealed statistically significant differences between the groups for any of the parameters analyzed in any volume of interest. For example, the mean bone volume fraction (BV/TV) of the defect, as measured by μCT, was 0.56 (95% confidence interval [CI], 0.44-0.68) for DBM hydrated with normal saline and 0.52 (95% CI, 0.40-0.65) for DBM hydrated with PRP, compared to 0.53 (95% CI, 0.45-0.61) and 0.54 (95% CI, 0.44-0.64) for the internal controls, respectively (P > 0.05).

CONCLUSION

In contrast to our hypotheses, no beneficial treatment effect of DBM with or without PRP was found for OCDs of the caprine talus.

Experimental study of the effect of autologous platelet-rich plasma on the early phases of osteoinduction by allogenic demineralized bone matrix

PURPOSE

To evaluate the effect of autologous platelet-rich plasma (PRP) on the early phases of osteoinduction by allogenic demineralized bone matrix (DBM) in rabbit intramuscular positions.

MATERIALS AND METHODS

Allogenic DBM was produced from bones of 3 healthy rabbits. In each of 6 experimental animals, 0.3 mL autologous PRP was prepared and 2 muscle pouches were created, where 250 mg DBM + PRP (experimental sites) and 250 mg DBM without PRP (control sites) were randomly implanted. Animals were euthanized 3 weeks postoperatively.

RESULTS

Histologic examination revealed uneventful healing in all cases, whereas remineralization of the periphery of the bone graft particles was a constant finding. In both control and experimental sites, fibroblasts and other mesenchymal cells (probably osteoprogenitor cells and preosteoblasts) were observed. The main histological difference was the recolonization of the empty lacunae of the bone graft particles by osteocytes at the control sites. The degradation of the graft at the control sites was statistically significantly quicker, although a statistically significant difference regarding the amount of the newly formed fibrous connective tissue was not observed.

CONCLUSION

The present study demonstrated that in this experimental model, the addition of PRP to DBM had a negative effect on the early phases of osteoinduction at 3 weeks of observation.

Bone ingrowth and vascular supply in experimental spinal fusion with platelet-rich plasma

STUDY DESIGN

Prospective investigation using a posterolateral spinal fusion (PLSF) model in rabbits.

OBJECTIVE

To assess the effects of platelet-rich plasma (PRP) alone, or with uncultured bone marrow, on bone ingrowth and angiogenesis in experimental PLSF.

SUMMARY OF BACKGROUND DATA

PRP is an autologous substance potentially beneficial to spinal fusion, because it includes several growth factors that may stimulate bone ingrowth and angiogenesis. However, the results of experimental and clinical investigations on the effectiveness of PRP in spinal fusion are controversial. This study was aimed at analyzing the influence of PRP on bone ingrowth and angiogenesis in experimental PLSF.

METHODS

Twenty White New Zealand rabbits underwent PLSF at L4-L5 level. The graft material included a ceramic carrier (Pro-Osteon 500R) loaded, in 7 rabbits, with PRP alone on the right side (group 1A) and with uncultured bone marrow in the left side (group 1B). In 7 rabbits, the ceramic carrier was used alone in the right side (group 2A), and with uncultured bone marrow in the left side (group 2B). Six rabbits (group 3) were sham operated on both right and left sides. Six months after surgery, the lumbar spine was harvested en bloc and evaluated by high-resolution radiographs (Faxitron, Wheeling, IL) and histology.

RESULTS

The radiographical outcome showed a fusion rate of 86% in groups 1A, 1B, and 2B and a fusion rate of 71% in group 2A. No specimen showed a solid fusion in the sham group. Histological analysis revealed new bone formation in the periapophyseal area in groups 1 and 2, but a complete bony bridge between the transverse processes was not observed in any specimen. In all groups, vascular density was significantly greater in the peri- compared with the interapophyseal region. In the PRP group, there was no evidence of increased vascular density in the grafted material compared with the other groups.

CONCLUSION

In experimental PLSF model in rabbits, PRP was not effective in promoting new bone formation and vascularization.

Can platelet-rich plasma (PRP) improve bone healing? A comparison between the theory and experimental outcomes

The increased concentration of platelets within platelet-rich plasma (PRP) provides a vehicle to deliver supra-physiologic concentrations of growth factors to an injury site, possibly accelerating or otherwise improving connective tissue regeneration. This potential benefit has led to the application of PRP in several applications; however, inconsistent results have limited widespread adoption in bone healing. This review provides a core understanding of the bone healing mechanisms, and corresponds this to the factors present in PRP. In addition, the current state of the art of PRP preparation, the key aspects that may influence its effectiveness, and treatment outcomes as they relate specifically to bone defect healing are presented. Although PRP does have a sound scientific basis, its use for bone healing appears only beneficial when used in combination with osteoconductive scaffolds; however, neither allograft nor autograft appear to be appropriate carriers. Aggressive processing techniques and very high concentrations of PRP may not improve healing outcomes. Moreover, many other variables exist in PRP preparation and use that influence its efficacy; the effect of these variables should be understood when considering PRP use. This review includes the essentials of what has been established, what is currently missing in the literature, and recommendations for future directions.

A new platelet cryoprecipitate glue promoting bone formation after ectopic mesenchymal stromal cell-loaded biomaterial implantation in nude mice

Introduction

This study investigated the promising effect of a new Platelet Glue obtained from Cryoprecipitation of Apheresis Platelet products (PGCAP) used in combination with Mesenchymal Stromal Cells (MSC) loaded on ceramic biomaterials to provide novel strategies enhancing bone repair.

Methods

PGCAP growth factor content was analyzed by ELISA and compared to other platelet and plasma-derived products. MSC loaded on biomaterials (65% hydroxyapatite/35% beta-TCP or 100% beta-TCP) were embedded in PGCAP and grown in presence or not of osteogenic induction medium for 21 days. Biomaterials were then implanted subcutaneously in immunodeficient mice for 28 days. Effect of PGCAP on MSC was evaluated in vitro by proliferation and osteoblastic gene expression analysis and in vivo by histology and immunohistochemistry.

Results

We showed that PGCAP, compared to other platelet-derived products, allowed concentrating large amount of growth factors and cytokines which promoted MSC and osteoprogenitor proliferation. Next, we found that PGCAP improves the proliferation of MSC and osteogenic-induced MSC. Furthermore, we demonstrated that PGCAP up-regulates the mRNA expression of osteogenic markers (Collagen type I, Osteonectin, Osteopontin and Runx2). In vivo, type I collagen expressed in ectopic bone-like tissue was highly enhanced in biomaterials embedded in PGCAP in the absence of osteogenic pre-induction. Better results were obtained with 65% hydroxyapatite/35% beta-TCP biomaterials as compared to 100% beta-TCP.

Conclusions

We have demonstrated that PGCAP is able to enhance in vitro MSC proliferation, osteoblastic differentiation and in vivo bone formation in the absence of osteogenic pre-induction. This clinically adaptable platelet glue could be of interest for improving bone repair.

Growth factors in the treatment of early osteoarthritis

Regenerative medicine is the science that studies the regeneration of biological tissues obtained through use of cells, with the aid of support structures and with biomolecules such as growth factors. As regards the growth factors the PRP, or the platelet-rich plasma, obtained from a withdrawal of autologous blood, concentrating the platelets, represents a safe, economical, easy to prepare and easy to apply source of growth factors. Numerous growth factors are in fact within the platelets and in particular a large number of them have a specific activity on neo-proliferation, on cartilage regeneration and in particular also an antiapoptotic effect on chondroblasts: - The PDGF which regulates the secretion and synthesis of collagen;- The EGF that causes cellular proliferation, endothelial chemotaxis and angiogenesis;- The VEGF that increases angiogenesis and vascular permeability;- The TGF-beta that stimulates the proliferation of undifferentiated MSC, stimulates chemotaxis of endothelial cells and angiogenesis;- The bFGF that promotes the growth and differentiation of chondrocytes and osteoblasts stimulates mitogenesis of mesenchymal cells, chondrocytes and osteoblasts. These properties have led to the development of studies that evaluated the efficacy of treatment of infiltrations in the knee and hip with platelet-derived growth factors. Regarding the knee it was demonstrated that in patients with moderate degree of gonarthrosis, the PRP is able to significantly reduce the pain and improve joint function, both on placebo and towards infiltrations with hyaluronic acid. The success of the treatment was proportional to the age of and inversely proportional to the severity of osteoarthritis according to Kellgren and Lawrence classification. The possibility of infiltrations guided with ultrasound into the hip led us to extend the indications also to hip arthrosis, as already showed by Sanchez. Even in coxarthrosis preliminary results at 6 and 12 months show that a cycle of 3 infiltrations of PRP has significantly decreased the pain and increased range of motion and joint function.

Transplantation of dental pulp stem cells and platelet-rich plasma for pulp regeneration

INTRODUCTION

The loss of dental pulp may weaken teeth, rendering them susceptible to reinfection, fracture, and subsequent tooth loss. Therefore, regeneration of pulp is considered an ideal treatment to preserve teeth. The aim of this study was to explore the capacity of dental pulp stem cells (DPSCs) and platelet-rich plasma (PRP) to regenerate dental pulp in canine mature permanent teeth.

METHODS

Pulpectomy with apical foramen enlarged to a #80 file was performed in 16 upper premolars of 4 beagle dogs. Four experimental groups were randomly established: (1) the blood clot group, (2) the autologous DPSCs group, (3) the PRP group, and (4) the DP + PRP group (a mixture of DPSCs and PRP). Four lower premolars without any further treatment after pulpectomy were used as the control group. All teeth were sealed with mineral trioxide aggregate and composite. Twelve weeks after transplantation, the teeth were subjected to radiographic and histologic examination.

RESULTS

Twenty-four of 32 experimental root canals gained newly formed tissues. All canals with an introduction of a blood clot showed histologic evidence of vital tissue formation. Cementum-like and periodontal ligament-like tissues along the internal root canal walls were typical structures in most cases. There is no significant difference between groups with or without autologous DPSC transplantation (exact chi-square test, P < .05).

CONCLUSIONS

New vital tissues can be regenerated in permanent canine teeth after pulpectomy and enlargement of the apical foramen. Histologically, transplantation of DPSCs and/or PRP into root canals showed no enhancement in new tissue formation compared with inducement of a blood clot into the root canals alone.

BMP-2 but not VEGF or PDGF in fibrin matrix supports bone healing in a delayed-union rat model

Treatment of delayed bone healing and non-unions after fractures, osteotomies or arthrodesis still is a relevant clinical challenge. Artificially applied growth factors can increase bone healing and progressively gain importance in clinical routine. The aim of this study was to determine the effects of rhPDGF-BB, rhVEGF-165, and rhBMP-2 in fibrin matrix on bone healing in a delayed-union rat model. Thirty-seven rats underwent a first operation where a standardized femoral critical size defect was created. A silicone spacer was implanted to impair vascularization within the defect. At 4 weeks the spacer was removed in a second operation and rhPDGF-BB, rhVEGF-165, or rhBMP-2 were applied in a fibrin clot. Animals in a fourth group received a fibrin clot without growth factors. At 8 weeks fibrin bound rhBMP-2 treated animals showed a significantly increased union rate and bone volume within the defect compared to the other groups. Single application of fibrin bound rhPDGF-BB and rhVEGF-165 failed to increase bone healing in our atrophic non-union model.

Demineralized bone matrix as a vehicle for delivering endogenous and exogenous therapeutics in bone repair

As a unique human bone extract approved for implant use, demineralized bone matrix (DBM) retains substantial amounts of endogenous osteoconductive and osteoinductive proteins. Commercial preparations of DBM represent a clinically accessible, familiar, widely used and degradable bone-filling device, available in composite solid, strip/piece, and semi-solid paste forms. Surgically placed and/or injected, DBM releases its constituent compounds to bone sites with some evidence for inducing new bone formation and accelerating healing. Significantly, DBM also has preclinical history as a drug carrier by direct loading and delivery of several important classes of therapeutics. Exogenous bioactive agents, including small molecule drugs, protein and peptide drugs, nucleic acid drugs and transgenes and therapeutic cells have been formulated within DBM and released to bone sites to enhance DBM's intrinsic biological activity. Local release of these agents from DBM directly to surgical sites in bone provides improved control of dosing and targeting of both endogenous and exogenous bioactivity in the context of bone healing using a clinically familiar product. Given DBM's long clinical track record and commercial accessibility in standard forms and sources, opportunities to formulate DBM as a versatile matrix to deliver therapeutic agents locally to bone sites in orthopedic repair and regenerative medicine contexts are attractive.

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.

Proliferation and differentiation of human tenocytes in response to platelet rich plasma: an in vitro and in vivo study

Platelet rich plasma (PRP) is the autologous plasma fraction with a platelet-rich cellular component which is enriched with a number of growth factors. Due to its availability and low cost, PRP has become an increasingly popular clinical tool as an alternative source of growth factors for various applications, for example, tendon regeneration but with limited success in clinical trials. The main objective of the current study was to determine whether activated PRP [i.e., platelet rich plasma-clot release (PRCR)] could be used to induce the proliferation and collagen synthesis in human tenocyte in vitro. The advantage of using PRCR is that the platelet-derived bioactive factors are more concentrated and could initiate a more rapid and accelerated healing response than PRP. Our results demonstrated that 10% PRCR treatment accelerated the extent of cell proliferation and collagen production by human tenocytes in vitro. The expression of specific tenocyte markers were similar to conventional fetal bovine serum (FBS)-treated tenocytes implanted in mice within 14 days of implantation in diffusion chambers. Moreover, relatively more collagen fibrils were evident in PRCR-treated tenocytes in vivo as compared to 10% FBS-treated cells. Overall, our feasibility study has indicated that PRCR can induce human tenocyte proliferation and collagen synthesis which could be implemented for future tendon regeneration in reconstructive surgeries.

Osteoinduction: a review of old concepts with new standards

Since the discovery of osteoinduction in the early 20th century, innovative biomaterials with osteoinductive potential have emerged. Over the last 50 years, however, our ability to describe biological phenomena accurately has been improved dramatically by advancements in cell and molecular biology. The aim of this review is to divide the osteoinduction phenomenon into 3 principles: (1) mesenchymal cell recruitment, (2) mesenchymal differentiation to bone-forming osteoblasts, and (3) ectopic bone formation in vivo. Furthermore, this review formulates guidelines for in vitro and in vivo experimental testing for accurately defining new biomaterials as osteoinductive. The use of growth factors with osteoinductive potential in periodontal and oral surgery is discussed. These concepts and guidelines aim to guide the future direction of emerging biomaterials in bone regeneration.

Osteoinductivity of demineralized bone matrix is independent of donor bisphosphonate use

BACKGROUND

Demineralized bone matrix is commonly used as a bone graft substitute, either alone or to supplement an osteoconductive material, because of its osteoinductive properties. The aging of the population has led to an increase in the number of prospective donors of demineralized bone matrix who have taken bisphosphonates to prevent osteoclast-mediated bone resorption. The aim of this study was to determine whether oral bisphosphonate usage affects the osteoinductivity of demineralized bone matrix from donors.

METHODS

Sex-matched and age-matched pairs of samples were provided by four tissue banks (three or four pairs per bank). Demineralized bone matrix donors without bisphosphonate treatment had a mean age (and standard deviation) of 69.1 ± 2.5 years, and donors with bisphosphonate treatment had a mean age of 68.9 ± 2.0 years. Each pair included one donor known to have taken bisphosphonates and one who had not taken bisphosphonates. Demineralized bone matrix previously confirmed as osteoinductive was the positive control, and heat-inactivated demineralized bone matrix was the negative control. Demineralized bone matrix incubated with 1 mL of phosphate-buffered saline solution containing 0, 0.002, 2.0, or 2000 ng/mL of alendronate was also tested. Gelatin capsules containing 15 mg of demineralized bone matrix were implanted bilaterally in the gastrocnemius muscle of male nude mice (eight implants per group). The mice were killed thirty-five days after implantation, and hind limbs were recovered and processed for histological analysis. Osteoinductivity was measured with use of a qualitative score and by histomorphometry.

RESULTS

Nine of fifteen samples from donors who had had bisphosphonate treatment and ten of fifteen samples from patients who had not had bisphosphonate treatment were osteoinductive. Qualitative mean scores were comparable (1.7 ± 0.4 for those without bisphosphonates and 1.9 ± 0.7 for those with bisphosphonates). Osteoinductive demineralized bone matrix samples produced ossicles of comparable size, regardless of bisphosphonate usage. Histomorphometric measurements of the area of new bone formation and residual demineralized bone matrix were also comparable. The addition of alendronate to control demineralized bone matrix did not affect its osteoinductivity.

CONCLUSIONS

Demineralized bone matrix samples from donors treated with bisphosphonates and donors not treated with bisphosphonates have the same ability to induce bone formation. However, it is not known if the quality of the new bone is affected, with subsequent consequences affecting bone remodeling.

The effect of Emdogain and platelet-derived growth factor on the osteoinductive potential of hydroxyapatite tricalcium phosphate

The aim of this study was to determine whether hydroxyapatite β-tricalcium phosphate (HA-TCP) either alone or coated with Emdogain (EMD) or recombinant human platelet-derived growth factor-BB (rhPDGF-BB) becomes osteoinductive in the murine thigh muscle model for osteoinduction. Twenty CD1 adult male mice had gelatin capsules implanted into the thigh muscle of both hind limbs. The capsules were either empty or contained one of the following: uncoated particulate HA-TCP, EMD-coated HA-TCP or rhPDGF-BB-coated HA-TCP. The implant sites were assessed histologically at 4 and 8 weeks. A semi-quantitative histological examination was performed to assess the inflammatory changes, reparative processes and osteoinduction within the graft site. At both 4 and 8 weeks, histological analysis failed to demonstrate any osteoinductive activity in any of the specimens from the experimental groups. A minimal chronic inflammatory response and foreign body reaction around the implanted materials was seen which reduced over time. The HA-TCP particles were embedded within fibrous connective tissue and were encapsulated by a dense cellular layer consisting of active fibroblasts and occasional macrophages with the thickness of this layer decreasing over time. The results of this study suggest that the use of commercially available HA-TCP alone or in combination with EMD or rhPDGF-BB is biocompatible but not osteoinductive in the murine thigh muscle model of osteoinduction. Coating HA-TCP with EMD or rhPDGF-BB does not enhance its osteoinductive potential.

Effects of autogenous growth factors on heterotopic bone formation of osteogenic cells in small animal model

AIMS

This study used a new approach to investigate the effective concentrations of growth factors released from platelet concentrate (PC) on the bone formation capacity of osteogenically differentiated rat bone marrow stromal cells (rBMSCs).

MATERIALS AND METHODS

Rat BMSCs and whole blood were harvested from 40 adult male Spraque-Dawly rats. Rat BMSCs were expanded in an osteogenic medium and seeded on inert collagenous bovine bone matrix (ICBM). Growth factors released from degranulated PC (GFs) containing TGF-β1 1 (25ng/ml)-10ng (250ng/ml) and rhBMP-2 400ng (10μg/ml) were suspended in 40μl platelet poor plasma (PPP) and applied on the ICBM-rBMSC constructs or ICBM only, respectively. The constructs were then transplanted in autologous hosts for 4 weeks. Concurrently, osteoblastic differentiation of rBMSCs on ICBM-rBMSC-PPP constructs was characterized in vitro.

RESULTS

Rat BMSCs in osteogenic medium exhibited phenotypes of mature osteoblasts. The amount of newly formed bone among groups of ICBM-rBMSC-PPP with and without GFs was not significantly different (p>0.05) and was significantly lower than a group of ICBM-PPP-BMP-2 (p<0.05).

CONCLUSIONS

Autogenous GFs had no effect on the capacity of rBMSCs to form new bone. The ability to measure the bone formation capacity of transplanted autologous cells and growth factors in a small animal model was demonstrated.

Treatment of long bone non-unions with polytherapy: indications and clinical results

The incidence of long bone non-unions has been estimated to range between 5 and 10%. Autologous bone graft usually harvested from the iliac crest continues to be the gold standard for biological enhancement of atrophic non-unions. However, its use has been hampered by minor and major donor site complications. Moreover despite possessing the properties of osteogenecity, osteoconductivity and some osteoinductivity the overall results of treatment have not been consistent with disappointing success rates at times. The concept of polytherapy for the treatment of non-unions, namely the simultaneous application of the three fundamental elements of the diamond concept, osteoprogenitor cells, growth factor and osteoconductive scaffold, appears to be an attractive alternative but more studies are desirable to validate this strategy.

Prospective, randomized, multi-center feasibility trial of rhPDGF-BB versus autologous bone graft in a foot and ankle fusion model

BACKGROUND

The increased morbidity and surgical time associated with harvesting autologous bone graft (ABG) have encouraged surgeons to develop synthetic orthobiologic alternatives. The recombinant form of platelet-derived growth factor (rhPDGF-BB), an angiogenic, mitogenic, and chemotactic cytokine, has been shown to significantly enhance bone formation in human periodontal osseous defects when combined with a tricalcium phosphate carrier (β-TCP). The purpose of this prospective, controlled, randomized, multi-center feasibility clinical trial was to compare the safety and efficacy of this biosynthetic bone graft substitute (Augment™ Bone Graft) to ABG during ankle and hindfoot fusion.

MATERIALS AND METHODS

Twenty adult subjects requiring ankle or hindfoot fusion from three U.S. centers were enrolled and randomized in a 2:1 ratio to receive Augment™ or ABG, respectively. Surgical approach and fixation techniques were standardized, and minimum followup was 9 months. The primary endpoint was radiographic osseous union, evaluated by a blinded independent radiologist. Secondary endpoints included assessment of clinical success, union rate by serial computed tomography (CT) examination, time to full weightbearing, AOFAS Ankle-Hindfoot Score (AOFAS), Foot Function Index (FFI), Short Form-12 (SF-12), and Visual Analog pain assessment Scale (Pain VAS).

RESULTS

At 36 weeks, 77% (10/13) of the Augment™ and 50% (3/6) of the ABG patients were fused based on radiographic criteria. There were two nonunions in the Augment™ group (9%, 2/14). Healing rates based on 12 week CT scanning (50% osseous bridging) were 69% (9/13) in the Augment™ and 60% (3/5) in the ABG groups, respectively. All functional outcome measures (FFI, AOFAS, SF-12), as well as the VAS pain scores, improved in both groups over time. Surgical procedure times lasted an average 26 minutes longer for the ABG as compared to the Augment™ populations. There were no device related serious adverse events in this study.

CONCLUSION

Based on the available data, the rate of radiographic union, time to full weightbearing, and outcomes scores between the Augment™ and ABG subjects appear comparable. Augment™ may represent a safe and efficacious treatment alternative to ABG during foot and ankle arthrodesis.

Effect of shock wave treatment on platelet-rich plasma added to osteoblast cultures

The aim of this study was to verify the effects on osteoblast cultures of adding a platelet-rich plasma (PRP) concentrate pretreated with 500 shock wave (SW) at an energy flow density of 0.17 mJ/mm(2), emitted by an electromagnetic generator Minilith SL1 (STORZ, Germany), reproducing the conditions of our previous study in which we apply SW directly on osteoblasts. Real-time PCR showed that in osteoblast cultures with added PRP pretreated with SW, there was an increased expression at 48 h of insulin-like growth factor binding protein 3 (IGFBP-3) and runt-related transcription factor 2 (RUNX2) and at 72 h, of collagen type I, osteocalcin, insulin-like growth factor 1 (IGF-1) as well as IGFBP-3. Western blotting confirmed the increased protein synthesis of IGFBP-3. This experience suggests that extracorporeal shock wave treatment (ESWT) should stimulate osteogenesis also by indirect platelets-mediated network. It therefore seems possible that combining the two methods, ESWT and bioengineering procedures to infiltrate PRP and growth factors, could be a successful approach.

Effects of platelet-rich plasma on intestinal anastomotic healing in rats: PRP concentration is a key factor

BACKGROUND

Few studies have examined the effects of platelet-rich plasma (PRP) on intestinal anastomotic healing. The applied preparation methods and PRP concentrations used in the few studies that have been carried out varied markedly. Therefore, the positive effects of PRP on the anastomotic healing process remain unclear. The aim of this study is to examine the effects of different concentrations of PRP on intestinal anastomotic healing.

MATERIAL AND METHODS

From SD rat blood, three different concentrations of plasma were prepared: high-concentrated PRP (H-PRP: platelet count 5 × 10(6)/mm(3)), low-concentrated PRP (L-PRP: 2 × 10(6)/mm(3)), and platelet-poor plasma (PPP). Male SD rats underwent proximal jejunal anastomosis and central venous catheterization. Rats were divided into four groups (n = 12 for each group): control, PPP, L-PRP, and H-PRP groups. Two types of PRP and PPP (0.21 mL) were applied to each anastomosis line, with the exception of the control group. Total parenteral nutrition (TPN) solutions were administered (151 kcal/kg/d). Five days after surgery, anastomotic bursting pressure (ABP) in situ and hydroxyproline concentration (HYP) in anastomotic tissue were evaluated.

RESULTS

The ABP values of control, PPP, L-PRP, and H-PRP groups were 171 ± 20, 174 ± 23, 189 ± 17, and 148 ± 25 mmHg, respectively. The HYP values of each group were 516 ± 130, 495 ± 123, 629 ± 120, and 407 ± 143 μg/g dry tissue. Compared with the other groups, the L-PRP group exhibited a significant increase in both ABP and HYP, while the H-PRP group exhibited a significant decrease in these two variables. As a result, L-PRP was considered to promote anastomotic wound healing, but H-PRP was considered to inhibit it. There was no significant difference between the PPP group and the control group.

CONCLUSIONS

PRP concentration plays a crucial role in the efficacy of PRP. PRP might exert positive effects on intestinal anastomotic healing in a dose-dependent manner up to a certain level, but adverse effects occur when it is highly concentrated. The essential PRP action appears to be driven by the platelets themselves.

Platelet autologous growth factors decrease the osteochondral regeneration capability of a collagen-hydroxyapatite scaffold in a sheep model

Background

Current research aims to develop innovative approaches to improve chondral and osteochondral regeneration. The objective of this study was to investigate the regenerative potential of platelet-rich plasma (PRP) to enhance the repair process of a collagen-hydroxyapatite scaffold in osteochondral defects in a sheep model.

Methods

PRP was added to a new, multi-layer gradient, nanocomposite scaffold that was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles. Twenty-four osteochondral lesions were created in sheep femoral condyles. The animals were randomised to three treatment groups: scaffold, scaffold loaded with autologous PRP, and empty defect (control). The animals were sacrificed and evaluated six months after surgery.

Results

Gross evaluation and histology of the specimens showed good integration of the chondral surface in both treatment groups. Significantly better bone regeneration and cartilage surface reconstruction were observed in the group treated with the scaffold alone. Incomplete bone regeneration and irregular cartilage surface integration were observed in the group treated with the scaffold where PRP was added. In the control group, no bone and cartilage defect healing occurred; defects were filled with fibrous tissue. Quantitative macroscopic and histological score evaluations confirmed the qualitative trends observed.

Conclusions

The hydroxyapatite-collagen scaffold enhanced osteochondral lesion repair, but the combination with platelet growth factors did not have an additive effect; on the contrary, PRP administration had a negative effect on the results obtained by disturbing the regenerative process. In the scaffold + PRP group, highly amorphous cartilaginous repair tissue and poorly spatially organised underlying bone tissue were found.

Platelet rich plasma injection grafts for musculoskeletal injuries: a review

In Europe and the United States, there is an increasing prevalence of the use of autologous blood products to facilitate healing in a variety of applications. Recently, we have learned more about specific growth factors, which play a crucial role in the healing process. With that knowledge there is abundant enthusiasm in the application of concentrated platelets, which release a supra-maximal quantity of these growth factors to stimulate recovery in non-healing injuries. For 20 years, the application of autologous PRP has been safely used and documented in many fields including; orthopedics, sports medicine, dentistry, ENT, neurosurgery, ophthalmology, urology, wound healing, cosmetic, cardiothoracic, and maxillofacial surgery. This article introduces the reader to PRP therapy and reviews the current literature on this emerging treatment modality. In summary, PRP provides a promising alternative to surgery by promoting safe and natural healing. However, there are few controlled trials, and mostly anecdotal or case reports. Additionally the sample sizes are frequently small, limiting the generalization of the findings. Recently, there is emerging literature on the beneficial effects of PRP for chronic non-healing tendon injuries including lateral epicondylitis and plantar fasciitis and cartilage degeneration (Mishra and Pavelko, The American Journal of Sports Medicine 10(10):1–5, 2006; Barrett and Erredge, Podiatry Today 17:37–42, 2004). However, as clinical use increases, more controlled studies are needed to further understand this treatment.

Influence of platelet-rich plasma on proliferation and osteogenic differentiation of skeletal muscle satellite cells: an in vitro study

OBJECTIVES

Platelet-rich plasma (PRP) is a new application of tissue engineering and a developing area for researchers and clinicians. The aim of this study was to assess the effect of PRP on the proliferation and osteogenic differentiation of skeletal muscle satellite cell (MSC) population and the ability of PRP to induce the production of some osteogeneic-related factors in vitro.

STUDY DESIGN

The PRP was obtained from Sprague-Dawley rats using 2 centrifugation techniques. Primary cultures of rat MSCs were exposed to various concentrations of PRP (0.16 × 10(8), 0.625 × 10(8), and 2.5 × 10(8) thrombocytes/carrier) on MSC proliferation using an MTT proliferation assay. Alkaline phosphatase (ALP) activity, Alizarin red S (AR) staining, calcium analyses and real-time reverse-transcription polymerase chain reaction (RT-PCR) of osteogenic-related genes were performed to study the effect of PRP on osteogenic differentiation of cultured MSCs population.

RESULTS

The platelet concentration and growth factors (GFs) in our PRP preparations were significantly higher than in the whole blood. PRP showed a dose-dependent stimulation of cell proliferation. The maximum effect was achieved with a concentration of 0.625 × 10(8) thrombocytes/carrier. ALP activity, AR staining, and calcium analyses showed enhanced cell osteogenic differentiation in the PRP group. The real-time RT-PCR results showed that PRP up-regulated osteocalcin at day 14 and type I collagen and osteopontin at day 7 compared with the control group.

CONCLUSIONS

The results of this study suggest that PRP containing osteoinductive GFs stimulates cell proliferation and osteogenic differentiation of rat-derived MSCs in vitro.

Use of platelet rich plasma to treat plantar fasciitis: design of a multi centre randomized controlled trial

Background

If conservative treatment for chronic plantar fasciitis fails, often a corticosteroid injection is given. Corticosteroid injection gives temporarily pain reduction, but no healing. Blood platelets initiate the natural healing rate. GPS^® gives an eightfold concentrate platelets of patients own blood. Injection of these platelets in the attachment of the fascia to the os calcis might induce a healing rate.

Methods and design

A randomized controlled multi centre trial will be performed. The study population consists of 120 patients of 18 years and older. Patients with chronic plantar fasciitis will be allocated randomly to have a steroid injection or an autologous platelet concentrate injections. Data will be collected before the procedure, 4,8,12,26 weeks and 1 year after the procedure.

The main outcome measures of this study are pain and function measured with questionnaires.

Conclusion

Recent literature show positive effects for the treatment of tendinosis with autologous platelet injections. The forthcoming trial will compare treatment for chronic plantar fasciitis with a steroid injection versus an autologous platelet injection. Our results will be published as soon as they become available.

Trial Registration

Trial registration number: http://www.clinicaltrials.gov NCT00758641.

Cages augmented with mineralized collagen and platelet-rich plasma as an osteoconductive/inductive combination for interbody fusion

STUDY DESIGN

After anterior cervical discectomy, fusion was radiologically, biomechanically, and histologically assessed in a sheep spine fusion model.

OBJECTIVE

To evaluate the efficacy of a platelet-rich plasma (PRP) application combined with a mineralized collagen matrix (MCM) as an alternative to autologous cancellous iliac crest bone grafts in a spine fusion model.

SUMMARY OF BACKGROUND DATA

PRP has the ability to stimulate bone and tissue healing. MCM is a recently developed osteoconductive material. Up to now, no comparative evaluation of PRP in combination with a MCM at the cervical spine has been performed in vivo.

METHODS

Twenty-four sheep (N = 8/group) underwent C3/4 discectomy and fusion: group 1, titanium cage filled with autologous cancellous iliac crest bone graft; group 2, titanium cage filled with MCM; and group 3, titanium cage filled with MCM and PRP. Radiographic evaluation was performed before surgery and after 1, 2, 4, 8, and 12 weeks, respectively. After 12 weeks, fusion sites were evaluated using functional radiographic views and quantitative computed tomographic scans to assess bone mineral density. Furthermore, histomorphologic and histomorphometrical analyses were performed to evaluate fusion.

RESULTS

In comparison with the titanium cage group filled with autologous cancellous iliac crest bone grafts representing the control group, MCM-alone group showed a slightly lower fusion rate in the radiographic and the histomorphometrical analysis. The addition of PRP could not enhance this finding. There was no significant difference between MCM and MCM + PRP group in radiologic and histologic findings.

CONCLUSION

The MCM alone is not able to replace autologous bone grafts. Early activation of the platelets by calcium, which is released from mineralized collagen, could be the reason for the insufficient osteoinductive effect of PRP. In consequence, the combined application of mineralized collagen and PRP had no significant osteoinductive effect in this model.

Comparison of mesenchymal stem cells from bone marrow and adipose tissue for bone regeneration in a critical size defect of the sheep tibia and the influence of platelet-rich plasma

Aim of the present study was to compare the osteogenic potential of bone marrow derived mesenchymal stem cells (BMSC) and adipose-tissue derived stem cells (ASC) and to evaluate the influence of platelet-rich plasma (PRP) on the osteogenic capacity of ASC in a large animal model. Ovine BMSC (BMSC-group) and ASC (ASC-group) were seeded on mineralized collagen sponges and implanted into a critical size defect of the sheep tibia (n=5 each). In an additional group, platelet-rich plasma (PRP) was used in combination with ASC (PRP-group). Unloaded mineralized collagen (EMPTY-group) served as control (n=5 each). Radiographic evaluation was performed every 2 weeks, after 26 weeks histological analysis was performed. Radiographic evaluation revealed a significantly higher amount of newly formed bone in the BMSC-group compared to the ASC-group at week 10 and compared to EMPTY-group from week 12 (all p<0.05). A superiority on radiographic level concerning bone formation of the PRP-group versus the empty control group was found (p<0.05), but not for the ASC-group. Histological analysis confirmed radiographic evaluation finding analogous significances. In conclusion, ASC seem to be inferior to BMSC in terms of their osteogenic potential but that can partially be compensated by the addition of PRP.

Reconstruction of goat tibial defects using an injectable tricalcium phosphate/chitosan in combination with autologous platelet-rich plasma

Injectable scaffolds held great promise for the reconstruction of bone defects. We prepared an injectable composite named PTC by combining TCP/chitosan (TC) with platelet-rich plasma (PRP). The objective of this study was to investigate the composite's mechanical and biological properties. First, we found that the introduction of PRP in TC showed no adverse effect on mechanical strength and that there were no significant differences in compressive strength between PTC and TC (P>0.05). In cell culture experiments, both cell count and alkaline phosphatase (ALP) activity measurements of PTC were higher than those of TC. The high levels of Cbfa1 and TGF-beta were detected early in PTC-induced MSCs by reverse transcriptase polymerase chain reaction. Bone formation following expression of collagen type I, osteocalcin, osteonectin and calcium nodules was also observed in PRP-induced MSCs. Finally, this composite was injected into the tibial bone defect in a goat model, and its ability to induce bone regeneration was observed. Sixteen weeks after the implantation of this composite, the tibial defects had completely recuperated, with significantly better formation of mature bone and less residual material than in the control. These results demonstrate that our composite, with its concomitant mechanical strength, biocompatibility, and osteoinductive properties, has significant potential as an injectable material for the treatment of bone defects.

Buffered platelet-rich plasma enhances mesenchymal stem cell proliferation and chondrogenic differentiation

The success of tissue engineering applications can potentially be dramatically improved with the addition of adjuncts that increase the proliferation and differentiation of progenitor or stem cells. Platelet-rich plasma (PRP) has recently emerged as a potential biologic tool to treat acute and chronic tendon disorders. The regenerative potential of PRP is based on the release of growth factors that occurs with platelet rupture. Its autologous nature gives it a significant advantage in tissue engineering applications. To test whether PRP may be useful specifically for cartilage regeneration, a cell culture experiment was devised in which mesenchymal stem cells (MSCs) were grown in control media or media enhanced with inactivated, buffered PRP. Proliferation 7 days after PRP treatment was increased: 1.041 versus 0.199 for the control media cells ( p<0.001). The messenger RNA (mRNA) level of the osteogenic marker RUNX2 was 52.84 versus 26.88 for the control group ( p<0.005). Likewise the mRNA level of the chondrogenic markers Sox-9 and aggrecan was 29.74 versus 2.29 for the control group ( p<0.001) and 21.04 versus 1.93 ( p<0.001), respectively. These results confirm that PRP enhances MSC proliferation and suggest that PRP causes chondrogenic differentiation of MSC in vitro.

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-rich plasma: current concepts and application in sports medicine

Platelet-rich plasma is defined as autologous blood with a concentration of platelets above baseline values. Platelet-rich plasma has been used in maxillofacial and plastic surgery since the 1990s; its use in sports medicine is growing given its potential to enhance muscle and tendon healing. In vitro studies suggest that growth factors released by platelets recruit reparative cells and may augment soft-tissue repair. Although minimal clinical evidence is currently available, the use of platelet-rich plasma has increased, given its safety as well as the availability of new devices for outpatient preparation and delivery. Its use in surgery to augment rotator cuff and Achilles tendon repair has also been reported. As the marketing of platelet-rich plasma increases, orthopaedic surgeons must be informed regarding the available preparation devices and their differences. Many controlled clinical trials are under way, but clinical use should be approached cautiously until high-level clinical evidence supporting platelet-rich plasma efficacy is available.

Osteoblastic differentiation of human mesenchymal stem cells with platelet lysate

Culture of expanded mesenchymal stem cells (MSCs) seeded on biomaterials may represent a clinical alternative to autologous bone graft in bone regeneration. Foetal bovine serum (FBS) is currently used for MSC expansion, despite risks of infectious disease transmission and immunological reaction due to its xenogenic origin. This study aimed to compare the osteogenic capacities of clinical-grade human MSCs cultured with FBS or allogenic human platelet lysate (PL). In vitro, MSCs cultured in PL both accelerate the expansion rate over serial passages and spontaneously induce osteoblastic gene expression such as alkaline phosphatase (ALP), bone sialoprotein (BSP), osteopontin (Op) and bone morphogenetic protein-2 (BMP-2). In vivo, ectopic bone formation is only observed on ceramics seeded with MSCs grown in PL medium implanted under the skin of immunodeficient mice for 7 weeks. In conclusion, allogenic human PL accelerates MSC proliferation and enhances MSC osteogenic differentiation.