PRP modulates expression of bone matrix proteins in vivo without long-term effects on bone formation

Comparison of the Effect of Platelet-rich Plasma (PRP) and Fat Graft on Autologous Bone Grafting in a Randomized-controlled Experimental Skull Model

Gold standard method for the treatment of critical-sized bone defects is the autogenous bone grafting procedure. A number of new and potentially useful adjuncts currently are being investigated to enhance the success of bone grafting. We propose to evaluate the effect of the most known and easily obtained 2 biological materials, fat graft and platelet-rich plasma (PRP), on bone graft healing. Twenty-seven New Zealand male rabbits were included in this randomized, controlled study. Two-sided 15-mm diameter bone defects were created in the parietal bones and the bones taken were replaced right-to-left and vice versa with 1 control group, 1 fat graft applied group, and the last one PRP applied group. Histologic evaluation and 3-dimensional maxillofacial computerized tomography were performed and bone density was calculated. In radiologic analysis, bone density was significantly different in the PRP group compared with the control and fat graft group in the 12th week ( P <0.05). In histologic scoring analysis, the PRP group had a better score than the control and fat graft group, while the fat graft group was worse than the control group in the 6th week ( P <0.05). The addition of PRP had a positive effect whereas fat graft had a negative effect on bone graft healing compared with the control group.

Magnesium-oxide-enhanced bone regeneration: 3D-printing of gelatin-coated composite scaffolds with sustained Rosuvastatin release

Critical-size bone defects are one of the main challenges in bone tissue regeneration that determines the need to use angiogenic and osteogenic agents. Rosuvastatin (RSV) is a class of cholesterol-lowering drugs with osteogenic potential. Magnesium oxide (MgO) is an angiogenesis component affecting apatite formation. This study aims to evaluate 3D-printed Polycaprolactone/β-tricalcium phosphate/nano-hydroxyapatite/ MgO (PCL/β-TCP/nHA/MgO) scaffolds as a carrier for MgO and RSV in bone regeneration. For this purpose, PCL/β-TCP/nHA/MgO scaffolds were fabricated with a 3D-printing method and coated with gelatin and RSV. The biocompatibility and osteogenicity of scaffolds were examined with MTT, ALP, and Alizarin red staining. Finally, the scaffolds were implanted in a bone defect of rat's calvaria, and tissue regeneration was investigated after 3 months. Our results showed that the simultaneous presence of RSV and MgO improved biocompatibility, wettability, degradation rate, and ALP activity but decreased mechanical strength. PCL/β-TCP/nHA/MgO/gelatin-RSV scaffolds produced sustained release of MgO and RSV within 30 days. CT images showed that PCL/β-TCP/nHA/MgO/gelatin-RSV scaffolds filled approximately 86.83 + 4.9 % of the defects within 3 months and improved angiogenesis, woven bone, and osteogenic genes expression. These results indicate the potential of PCL/β-TCP/nHA/MgO/gelatin-RSV scaffolds as a promising tool for bone regeneration and clinical trials.

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Treatment strategies for meniscal lesions: from past to prospective therapeutics

Menisci play an important role in the biomechanics of knee joint function, including loading transmission, joint lubrication, prevention of soft tissue impingement during motion and joint stability. Meniscal repair presents a challenge due to a lack of vascularization that limits the healing capacity of meniscal tissue. In this review, the authors aimed to untangle the available treatment options for repairing meniscal tears. Various surgical procedures have been developed to treat meniscal tears; however, clinical outcomes are limited. Consequently, numerous researchers have focused on different treatments such as the application of exogenous and/or autologous growth factors, scaffolds including tissue-derived matrix, cell-based therapy and miRNA-210. The authors present current and prospective treatment strategies for meniscal lesions.

An In Vitro and In Vivo Comparison of Osteogenic Differentiation of Human Mesenchymal Stromal/Stem Cells

The use of stem cells in regenerative medicine, including tissue engineering and transplantation, has generated a great deal of enthusiasm. Mesenchymal stromal/stem cells (MSCs) can be isolated from various tissues, most commonly, bone marrow but more recently adipose tissue, dental pulp, and Wharton's jelly, to name a few. MSCs display varying phenotypic profiles and osteogenic differentiating capacity depending and their site of origin. MSCs have been successfully differentiated into osteoblasts both in vitro an in vivo but discrepancies exist when the two are compared: what happens in vitro does not necessarily happen in vivo, and it is therefore important to understand why these differences occur. The osteogenic process is a complex network of transcription factors, stimulators, inhibitors, proteins, etc., and in vivo experiments are helpful in evaluating the various aspects of this osteogenic process without distractions and confounding variables. With that in mind, the results of in vitro experiments need to be carefully considered and interpreted with caution as they do not perfectly replicate the conditions found within living organisms. This is where in vivo experiments help us better understand interactions that might occur in the osteogenic process that cannot be replicated in vitro. Potentially, these differences could also be exploited to develop an optimal MSC cell therapeutic product that can be used for bone disorders. There are many bone disorders, most of which cause a great deal of discomfort. Clinically acceptable protocols could be developed in which MSCs are used to aid in bone regeneration providing relief for patients with chronic pain. The aim of this review is to examine the differences between studies conducted in vitro and in vivo with regard to the osteogenic process to better define the gaps in current osteogenic research. By better understanding osteogenic differentiation, we can better define treatment strategies for various bone disorders.

The effectiveness of locally injected platelet-rich plasma on orthodontic tooth movement acceleration

OBJECTIVES

To critically appraise the current evidence available from animal studies pertaining to the effectiveness of platelet-rich plasma (PRP) in accelerating orthodontic tooth movement.

MATERIALS AND METHODS

Electronic searches of nine databases were conducted up to June 2020, followed by a hand search of the reference list of eligible studies. The study design required was prospective controlled animal studies. The primary outcome assessed was the rate of orthodontic tooth movement. The secondary outcome evaluated was histological changes after PRP application. Following study retrieval and selection, relevant data were extracted. Risk-of-bias (RoB) assessment was done using the Systematic Review Center for Laboratory Animal Experimentation's Risk of Bias Tool (SYRCLE's Risk of Bias Tool). Two review authors conducted the work of searching, study selection, and quality assessment independently and in duplicate.

RESULTS

Of 193 studies, 5 animal studies were included in this systematic review. Three studies found a positive correlation between PRP injection and tooth movement acceleration, along with corresponding histological changes. Two studies detected no significant difference in tooth movement rate after PRP application.

CONCLUSIONS

Based on the current limited evidence, the efficacy of PRP on tooth movement acceleration remains debatable. More well-designed randomized controlled trials involving humans are called for to obtain more clinically significant conclusions.

Bone regeneration in both small and large preclinical bone defect models using an injectable polymer-based substitute containing hydroxyapatite and reconstituted with saline or autologous blood

Microbeads consisting of pullulan and dextran supplemented with hydroxyapatite have recently been developed for bone tissue engineering applications. Here, we evaluate the bone formation in two different preclinical models after injection of microbeads reconstituted with either saline buffer or autologous blood. Addition of saline solution or autologous blood to dried microbeads packaged into syringes allowed an easy injection. In the first rat bone defect model performed in the femoral condyle, microcomputed tomography performed after 30 and 60 days revealed an important mineralization process occurring around and within the core of the microbeads in both conditions. Bone volume/total volume measurements revealed no significant differences between the saline solution and the autologous blood groups. Histologically, osteoid tissue was evidenced around and in contact of the microbeads in both conditions. Using the sinus lift model performed in sheep, cone beam computed tomography revealed an important mineralization inside the sinus cavity for both groups after 3 months of implantation. Representative Masson trichrome staining images showed that bone formation occurs at the periphery and inside the microbeads in both conditions. Quantitative evaluation of the new bone formation displayed no significant differences between groups. In conclusion, reconstitution of microbeads with autologous blood did not enhance the regenerative capacity of these microbeads compared to the saline buffer group. This study is of particular interest for clinical applications in oral and maxillofacial surgery.

The effects of oyster shell/alpha-calcium sulfate hemihydrate/platelet-rich plasma/bone mesenchymal stem cells bioengineering scaffold on rat critical-sized calvarial defects

Engineering scaffolds combining natural biomineral and artificially synthesized material hold promising potential for bone tissue regeneration. We fabricated a bioengineering scaffold, oyster shell (OS) and alpha-calcium sulfate hemihydrate (α-CSH) as scaffold, platelet-rich plasma (PRP) as provider of growth factors and bone mesenchymal stem cells (BMSCs) as seed cells, and determined it could be applied as a new type of bone graft substitutes by rat calvarial defects repairing experiment in vitro and in vivo. SEM showed that the mean diameter of the pores was about 150 μm with a range of 50-200 μm, and scaffold's porosity was ~27.4% by Archimedes' Principle. In vitro, Scaffold + BMSCs + PRP group presented a higher ALP activity compared with other groups by ELISA (P < 0.05). But the expression of OC was not detectable on day 4 or 8. The MTT assay showed that the relative cell number of BMSCs+PRP group increased significantly (P < 0.05). In vivo, the smallest defect area of skull and highest volume of regenerated new bone were observed in Scaffold + PRP + BMSCs group by X-ray and Micro-CT analysis (P < 0.05). And the similar results also were observed in HE and Masson staining. The immunohistochemistry staining for osteogenic marker proteins ALP and OC showed that the most obvious positive staining was observed in Scaffold + PRP + BMSCs group (P < 0.05). The expression of inflammatory markers IL-6 and TNF-α was the lowest in control group (P < 0.05). In conclusion, a bioengineering scaffold based on OS, created by simply combining α-CSH and PRP and implanting with BMSCs, could be clinically useful and has marked advantages as a targeted, off-the-shelf, cell-loaded treatment option for the bone healing of critical-size calvarial defects.

Experimental investigation of effects of platelet-rich plasma on early phases of orthodontic tooth movement

INTRODUCTION

The aim of this study was to evaluate the effects of platelet-rich plasma on orthodontic tooth movement in rats.

METHODS

We divided 48 Wistar male albino rats into 3 groups: control group, platelet-rich plasma group, and platelet-poor plasma group. The rats in all study groups had orthodontic tooth movement of their maxillary right first molars. Either platelet-rich plasma or platelet-poor plasma was injected into the animals in the platelet-rich plasma and platelet-poor plasma groups, respectively; the rats in the control group had no injection. Distances between the maxillary molar and incisor were measured on days 0, 1, 3, 7, and 14. Active osteoblast numbers in tension sites and osteoclast numbers in compression sites were examined histologically. Immunohistochemical evaluations of tartrate-resistant acid phosphatase (TRAP), transforming growth factor-β (TGF-β), and alkaline phosphatase (ALP) expressions were also performed.

RESULTS

The rats in the platelet-rich plasma group showed less tooth movement than those in the control group at day 3. At day 14, maximum tooth movement was observed in all groups. However, there was no statistical significance among the groups at day 14. In terms of osteoclast and osteoblast cells, no significant differences were observed in any group or at any time. Also, there were no significant differences in TRAP, ALP, and TGF-β expressions in the groups.

CONCLUSIONS

The application of platelet-rich plasma was not beneficial as an adjunct to orthodontic treatment.

Effect of Platelet-rich Plasma on Implant Bone Defects in Rabbits Through the FAK/PI3K/AKT Signaling Pathway

Platelet-rich plasma (PRP) has been shown to be a beneficial growth factor for bone tissue healing and is used in implantology. The aim of this study was to investigate the effects of PRP on bone defects in rabbits. Twenty rabbits were used to establish the implant bone defect model in this study. An intrabony defect (5mm × 5mm × 3mm) was created in alveolar bone in the lower jar of each rabbit. The wound was treated with PRP. The expression of platelet-derived growth factor BB (PDGFBB) was assessed by enzyme-linked immunosorbent assay (ELISA). Focal adhesion kinase (FAK) and related phosphatidylinositol 3-kinase (PI3K)/AKT (protein kinase B) levels were measured by Western blot. The results show that PRP could significantly improve the bone healing process when compared with control, and 10% PRP could markedly increase fibroblast proliferation 48-h post treatment. PDGFBB was higher in the PRP group than that in the control group. PRP treatment also could elevate the phosphorylation of FAK and PI3K/AKT, although the inhibitor of PDGFR could reverse this trend. These results suggest that PRP treatment improves the bone healing process through the FAK/PI3K/AKT pathway.

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.

The Bone Regeneration Using Bone Marrow Stromal Cells with Moderate Concentration Platelet-Rich Plasma in Femoral Segmental Defect of Rats

Background:

Platelet-rich plasma (PRP) can provide an assortment of growth factors, but how PRP effects bone regeneration is still unknown. The aim of the study was to explore an optimal method of using PRP and bone marrow stromal cells (BMSCs).

Methods:

An in vitro experiment was first conducted to determine an appropriate quantity of PRP. BMSCs were cultured with PRP of different concentrations to assess cell proliferation and osteogenic differentiation. Following the in vitro study, a rat femoral segmental defect model was used. Five collagen mixtures consisting of different concentrations of PRP and BMSCs were prepared as follows, i) BMSCs and PRP (platelet 20 x 10⁴/µl), ii) BMSCs and PRP (platelet 100 x 10⁴/µl), iii) BMSCs and PRP (platelet 500 x 10⁴/µl), iv) BMSCs, and v) PRP group (platelet 100 x 10⁴/µl), were used to fill defect. New bone formation was evaluated by soft X-ray and histologic analyses were performed at 2, 4, 6 and 8 weeks postoperatively.

Results:

The cell proliferation increased PRP concentration-dependently. Cellular alkaline phosphatase activity was higher in moderate concentration than high or low concentration group’s in vitro study. In vivo study, the bone fill percentage of newly formed bone in BMSCs and PRP (platelet 100 x 10⁴/µl) was 46.9% at 8 weeks and increased significantly compared with other groups.

Conclusion:

BMSCs with moderate level of PRP significantly enhanced bone formation in comparison with BMSCs or PRP transplant in a rat femoral defect model.

The healing effect of platelet-rich plasma on xenograft in peri-implant bone defects in rabbits

Background

The association of biomaterial combined with repair factor-like platelet-rich plasma (PRP) has prospective values. Bovine-derived xenograft has been identified as an osteoconductive and biocompatible grafting material that provides osseointegration ability. PRP has become a valuable adjunctive agent to promote healing in a lot of dental and oral surgery procedures. However, there are controversies with respect to the regenerative capacity of PRP and the real benefits of its use in bone grafts. The purpose of this study was to assess the influence of PRP combined with xenograft for the repair of peri-implant bone defects.

Methods

Twelve rabbits were used in this study, and the experimental surgery with implant installation was performed simultaneously. Autologous PRP was prepared before the surgical procedure. An intrabony defect (7.0 mm in diameter and 3.0 mm deep) was created in the tibia of each rabbit; then, 24 titanium dental implants (3.0 mm in diameter and 8.5 mm long) were inserted into these osteotomy sites. Thus, a standardized gap (4.0 mm) was established between the surrounding bony walls and the implant surface. The gaps were treated with either xenograft alone (control group) or xenograft combined with PRP (experimental group). After healing for 1, 2, 3, 4, 5, and 6 weeks, the rabbits were sacrificed with an overdose of KCl solution. Two rabbits were killed at each time, and the samples including dental implants and surrounding bone were collected and processed for histological analysis.

Results

More newly formed bone and a better bone healing process were observed in control group. The histomorphometric analysis revealed that the mean percentage of bone-to-implant contact in the control group was significantly higher than that of the experimental group (25.23 vs. 8.16 %; P < 0.05, independent-simple t test, analysis of variance [ANOVA]).

Conclusions

The results indicate that in the addition of PRP to bovine-derived xenograft in the repair of bone defects around the implant, PRP may delay peri-implant bone healing.

PERIPHERAL NERVE REGENERATION: CELL THERAPY AND NEUROTROPHIC FACTORS

Peripheral nerve trauma results in functional loss in the innervated organ, and recovery without surgical intervention is rare. Many surgical techniques can be used for nerve repair. Among these, the tubulization technique can be highlighted: this allows regenerative factors to be introduced into the chamber. Cell therapy and tissue engineering have arisen as an alternative for stimulating and aiding peripheral nerve regeneration. Therefore, the aim of this review was to provide a survey and analysis on the results from experimental and clinical studies that used cell therapy and tissue engineering as tools for optimizing the regeneration process. The articles used came from the LILACS, Medline and SciELO scientific databases. Articles on the use of stem cells, Schwann cells, growth factors, collagen, laminin and platelet-rich plasma for peripheral nerve repair were summarized over the course of the review. Based on these studies, it could be concluded that the use of stem cells derived from different sources presents promising results relating to nerve regeneration, because these cells have a capacity for neuronal differentiation, thus demonstrating effective functional results. The use of tubes containing bioactive elements with controlled release also optimizes the nerve repair, thus promoting greater myelination and axonal growth of peripheral nerves. Another promising treatment is the use of platelet-rich plasma, which not only releases growth factors that are important in nerve repair, but also serves as a carrier for exogenous factors, thereby stimulating the proliferation of specific cells for peripheral nerve repair.

Platelet-Rich Plasma: A Study of the Variables that May Influence Its Effect on Bone Regeneration

BACKGROUND

Currently, the use of platelet-rich plasma in bone regeneration is a real option, although more than one opinion has alerted us to the absence of clinical benefits.

PURPOSE

Analysis of the factors able to modify the characteristics of the platelet preparation obtained by Curasan, Plasma Rich in Growth Factors (PRGF), Platelet Concentrate Collection System (PCCS) and SmartPrep systems, relating them to the type of clinical application and the final bone regeneration achieved.

MATERIALS AND METHODS

A search was conducted in PubMed using the keywords "platelet-rich plasma," "PRP," "platelet rich growth factors," and "oral bone regeneration." Four widely accepted protocols for the obtention of PRP (above) were analyzed. Any clinical studies with controls, using the four preparation protocols and with a 4 to 6 weeks follow-up period were compared. The protocols were also grouped according to the type of PRP application: PRP-alone, with bone, or with bone substitutes.

RESULTS

Bone regeneration was not achieved in any of the cases using PRP obtained by Curasan and PCCS systems, whereas PRP obtained by SmartPrep achieved it only in one in three published cases and PRGF in one in six.

CONCLUSION

Based on the poor results observed in current literature, the use of PRP in oral surgery cannot be recommended.

Does platelet-rich plasma enhance healing in the idiopathic bone cavity? A single-blind randomized clinical trial

The presence of an idiopathic bone cavity (IBC) is usually identified during routine dental radiographic examinations. The purpose of this study was to investigate the effect of platelet-rich plasma (PRP) on bone healing in the idiopathic bone cavity. This was a single-blind randomized clinical trial. Twenty-four subjects were assigned randomly to two groups. Subjects in group 1 received PRP through a buccal window approach, and those in group 2 underwent conventional management via the creation of a window on the buccal wall and curettage of the walls of the defect. Subjects were followed up at 3, 6, and 9 months after the intervention. The amount of bone formation as determined on panoramic radiographs was divided into four categories: stage 1: ≤25% of the defect showed opacity; stage 2: 25-50% of the defect showed opacity; stage 3: 50-75% of the defect showed opacity; and stage 4: >75% of the defect showed opacity. There was a significant difference between the two groups with regard to the various healing stages at the three time points (P<0.05). When compared with conventional management of the idiopathic bone cavity, the use of PRP may enhance bone formation.

Effect of Platelet-Rich Plasma on the Healing of Mandibular Defects Treated With Fresh Frozen Bone Allograft: A Radiographic Study in Dogs

The purpose of this study was to radiographically analyze the effect of autologous platelet rich plasma (PRP) on the healing of fresh frozen bone allograft (FFBA) placed in surgically created resection defects in mandibles of dogs. Bilateral resection defects measuring 1.5 cm × 1 cm were surgically created on the inferior border of the mandible in 10 adult male dogs. The defects were randomly divided into three groups: C, FFBA, and FFBA/PRP. In Group C, the defect was filled by blood clot only. In Group FFBA, the defect was filled with particulate fresh frozen bone allograft. In Group FFBA/PRP, it was filled with particulate fresh frozen bone allograft combined with PRP. At 90 days postoperative, standardized radiographs of the mandibles were obtained and results were quantitatively evaluated. Analysis of digitized radiographs indicated that non-PRP grafts were significantly less dense than the PRP grafts. Group FFBA/PRP also presented a statistically greater mineralized tissue area than Groups C and FFBA. Within the limits of this study, it can be concluded that PRP enhanced the healing of FFBA in resection defects in mandibles of dogs.

Effects of platelet-poor plasma, platelet-rich plasma, and platelet-rich fibrin on healing of extraction sockets with buccal dehiscence in dogs

Alveolar bone resorption generally occurs during healing after tooth extraction. This study aimed to evaluate the effects of platelet-poor plasma (PPP), platelet-rich plasma (PRP), and platelet-rich fibrin (PRF) on healing in a ridge-augmentation model of the canine socket with dehiscence of the buccal wall. The third mandibular premolars of 12 beagle dogs were extracted and a 3 mm buccal dehiscence from the alveolar crest to the buccal wall of the extraction socket was created. These sockets were then divided into four groups on the basis of the material used to fill the sockets: PPP, PRP, PRF, and control (no graft material) groups. Results were evaluated at 4 and 8 weeks after surgery. The ultrastructural morphology and constructs of each blood product were studied by a scanning electron microscope (SEM) or calculating concentrations of platelets, fibrinogen, platelet-derived growth factor, and transforming growth factor-β. A total of five microcomputed tomography images of specimens were selected for measurement, and the area occupied by the newly formed bone as well as the horizontal bone width were measured. Moreover, decalcified tissue specimens from each defect were analyzed histologically. The median area of new bone at 4 and 8 weeks and median horizontal bone width at 8 weeks were the highest in the PPP group. However, bone maturation in the PRF and the PRP groups was more progressed than that in the PPP and control groups. By SEM findings, the PRF group showed a more highly condensed fibrin fiber network that was regularly arranged when compared with the PPP and PRP groups. The growth factors released from platelets in PRP indicated higher concentrations than that in PRF. Under more severe conditions for bone formation, as in this experiment, the growth factors released from platelets had a negative effect on bone formation. This study showed that PPP is an effective material for the preservation of sockets with buccal dehiscence.

Fragmented Adipose Tissue Transplanted to Craniofacial Deformities Induces Bone Repair Associated with Immunoexpression of Adiponectin and Parathyroid Hormone 1-Receptor

Objective

This study analyzed the influence of autogenous white adipose tissue on bone matrix development in critical-size defects created in rabbit calvaria.

Materials and Methods

A 15-mm-diameter defect was created in the calvaria of 42 rabbits. Twenty-one rabbits were treated with 86 mm3 of immediate transplant of fragmented white subcutaneous adipose tissue (WSAT); the others constituted the control group (sham). The animals were euthanized at 7, 15, and 40 days postsurgery (n = 7), and the histological data were analyzed by histomorphometry and immunohistochemistry using the anti-adiponectin and parathyroid hormone 1-receptor (PTH1R) antibodies.

Results

The calvariae treated with fragmented WSAT demonstrated significant bone formation. These results coincided with the significant presence of immunopositivity to adiponectin and PTH1R in loci, which in turn coincided with the increase in bonelike matrix deposited both in fat tissue stroma and adipocytes' cytoplasm. In contrast, the control group revealed a small amount of bone-matrix deposition and presented scarce PTH1R expression and a lack of immunostain for adiponectin.

Conclusion

These results indicate that transplant of fragmented white subcutaneous adipose tissue may be an alternative to treatment of craniofacial bone deformities because adipose tissue suffers from osseous metaplasia and exhibits immunoexpression of the adiponectin and PTH1R, which are proteins associated with bone metabolism

Weak link of tendon-bone healing and a control experiment to promote healing

OBJECTIVE

This study aims to observe the mechanical weak point and histological features of tendon-bone interface after anterior cruciate ligament reconstructive surgery and to explore the tendon-bone healing effects of the platelet-rich gel (PRG) + deproteinized bone (DPB) compound.

METHODS

A total of 48 New Zealand white rabbits were randomly divided into normal group, model (without embedding), experimental (embedded with the PRG + DPB compound), and control (embedded with DPB) groups. The rabbits were executed at 2, 4, 8, and 12 weeks after the operation. Then, micro-computed tomography scan and uniaxial tensile test were conducted. The fractured specimens were subjected to histological observation.

RESULTS

At 4, 8, and 12 weeks after the operation, the bone density of the tendon-bone bound section of the experimental group was higher than that of the other groups (P < 0.05). At 4 and 8 weeks, the maximum tensile load of the experimental group was obviously higher than that of the control and model groups (P < 0.05). Histological observation indicated that the tendon-bone interface in the experimental group had more cartilage and bone tissue growing toward the internal tendon, but the fracture layer mainly occurred in the non-ankylosed part.

CONCLUSION

The mechanical weak point of the early tendon-bone interface was in the immature fibrous tissue. The PRG + DPB compound can effectively trigger tendon-bone healing by promoting the maturation and ossification of the tendon-bone tissue. This compound improved the tensile strength of the healing interface and reduced bone tunnel enlargement.

The effect of rhBMP-2 and PRP delivery by biodegradable β-tricalcium phosphate scaffolds on new bone formation in a non-through rabbit cranial defect model

This study evaluated whether the combination of biodegradable β-tricalcium phosphate (β-TCP) scaffolds with recombinant human bone morphogenetic protein-2 (rhBMP-2) or platelet-rich plasma (PRP) could accelerate bone formation and increase bone height using a rabbit non-through cranial bone defect model. Four non-through cylindrical bone defects with a diameter of 8-mm were surgically created on the cranium of rabbits. β-TCP scaffolds in the presence and absence of impregnated rhBMP-2 or PRP were placed into the defects. At 8 and 16 weeks after implantation, samples were dissected and fixed for analysis by microcomputed tomography and histology. Only defects with rhBMP-2 impregnated β-TCP scaffolds showed significantly enhanced bone formation compared to non-impregnated β-TCP scaffolds (P < 0.05). Although new bone was higher than adjacent bone at 8 weeks after implantation, vertical bone augmentation was not observed at 16 weeks after implantation, probably due to scaffold resorption occurring concurrently with new bone formation.

Platelet-rich plasma-assisted guided bone regeneration for ridge augmentation: a randomized, controlled clinical trial

BACKGROUND

Platelet-rich plasma (PRP) contains a number of biologically active growth factors, and previous studies have reported conflicting ridge augmentation results. The primary aim of this randomized, controlled, masked, clinical trial was to determine if PRP combined with a rapidly resorbing cancellous allograft would enhance the regenerative result compared with an allograft without PRP.

METHODS

Thirty-two patients with an edentulous ridge defect were sequentially entered into the study; four were excluded from data analysis. Fourteen patients received a cancellous allograft (CAN group) and the other 14 received a cancellous allograft mixed with PRP (PRP group). All 28 grafted sites were covered with a resorbable polylactide membrane. After elevation of a full-thickness flap, horizontal ridge dimensions were measured with a digital caliper at the crest and 5 mm apical to the crest. Vertical ridge dimensions were measured from a tooth-supported stent. All sites were reentered at 4 months, and a trephine core was obtained for histologic analysis before implant placement.

RESULTS

The crestal ridge width for the CAN group had a mean gain of 2.0 ± 1.2 mm, whereas the PRP group gained 2.9 ± 1.0, and the difference was statistically significant between groups (P <0.05). The percent vital bone was 36% ± 14% for the CAN group compared with 51% ± 15% for the PRP group and was statistically significant between groups (P <0.05). Loss of augmented ridge width was 34% ± 17% for the CAN group and 28% ± 17% for the PRP group (P >0.05).

CONCLUSION

These clinical and histologic findings suggest that PRP enhanced bone regeneration and resulted in increased horizontal bone gain and percentage vital bone.

Implants in bone: part II. Research on implant osseointegration: material testing, mechanical testing, imaging and histoanalytical methods

PURPOSE

In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, it must undergo rigorous testing. To correctly interpret the results of studies on implant material osseointegration, it is necessary to have a sound understanding of all the testing methods. The aim of this overview is to elucidate the methods that are used for the experimental evaluation of the osseointegration of implant materials.

DISCUSSION

In recent decades, there has been a constant proliferation of new materials and surface modifications in the field of dental implants. This continuous development of innovative biomaterials requires a precise and detailed evaluation in terms of biocompatibility and implant healing before clinical use. The current gold standard is in vivo animal testing on well validated animal models. However, long-term outcome studies on patients have to follow to finally validate and show patient benefit.

CONCLUSION

No experimental set-up can provide answers for all possible research questions. However, a certain transferability of the results to humans might be possible if the experimental set-up is carefully chosen for the aspects and questions being investigated. To enhance the implant survival rate in the rising number of patients with chronic diseases which compromise wound healing and osseointegration, dental implant research on compromised animal models will further gain importance in future.

The use of platelet-rich plasma in plastic surgery: a systematic review

OBJECTIVE

The study's aim was to evaluate the available evidence regarding the use of platelet-rich plasma in plastic and reconstructive surgery, through implementation of a systematic review of the literature.

DATA SOURCES

PubMed and The Cochrane Library were searched using MeSH terms: 'platelet rich plasma' and 'plastic surgery' for all publications up to July 2011. All English, German, French and Dutch papers were included. In addition, the reference lists of relevant articles were searched for potentially appropriate publications.

STUDY SELECTION

Included studies needed to report on topics related to plastic and reconstructive surgery, mentioning at least one clinical end point. Both in vivo and in vitro comparative studies, performed in humans or animals, were included. A total of 82 publications were found, of which 40 studies met the inclusion criteria and were relevant to be used in this systematic review.

DATA EXTRACTION

Data from retrieved studies were reviewed and tabulated according to year of publication, study design, human or animal studies, characteristics of the population, mode of application, outcomes and preparation method.

DATA SYNTHESIS

A total of 15 randomised controlled trials and 25 case-control studies were found. Thirty-six publications demonstrated favourable outcomes with the use of platelet-rich plasma. The included articles were divided into three topics related to plastic surgery: wound healing, fat grafting and bone grafting.

CONCLUSIONS

This systematic review describes a substantially beneficial effect of platelet-rich plasma for several indications, including a better wound healing rate, an increased survival rate of fat grafts and an enhancement of bone graft regeneration.

The role of platelet rich plasma in musculoskeletal science

The idea of using platelet rich plasma (PRP) in medicine has been around since the 1970s. It is only more recently that its use has been employed in the area of musculoskeletal science. Platelet rich plasma in this area has received much media attention being used by many celebrity sports athletes for musculoskeletal injuries. Therefore it is important for the musculoskeletal practitioner to be aware of the concepts surrounding its use and application. In this article we cover what platelet rich plasma is, how it is prepared and administered, its potential clinical application, and what the current literature discusses in the various areas of musculoskeletal science.

Enhancement of osteogenic differentiation of human adipose derived stem cells by the controlled release of platelet lysates from hybrid scaffolds produced by supercritical fluid foaming

A new generation of scaffolds capable of acting not only as support for cells but also as a source of biological cues to promote tissue regeneration is currently a hot topic of in bone Tissue Engineering (TE) research. The inclusion of growth factor (GF) controlled release functionalities in the scaffolds is a possible strategy to achieve such goal. Platelet Lysate (PL) is an autologous source of GFs, providing several bioactive agents known to act on bone regeneration. In this study, chitosan-chondroitin sulfate nanoparticles loaded with PL were included in a poly(D,L-lactic acid) foam produced by supercritical fluid foaming. The tridimensional (3D) structures were then seeded with human adipose-derived stem cells (hASCs) and cultured in vitro under osteogenic stimulus. The osteogenic differentiation of the seeded hASCs was observed earlier for the PL-loaded constructs, as shown by the earlier alkaline phosphatase peak and calcium detection and stronger Runx2 expression at day 7 of culture, in comparison with the control scaffolds. Osteocalcin gene expression was upregulated in presence of PL during all culture period, which indicates an enhanced osteogenic induction. These results suggest the synergistic effect of PL and hASCs in combinatory TE strategies and support the potential of PL to increase the multifunctionality of the 3D hybrid construct for bone TE applications.

Histological results after maxillary sinus augmentation with Straumann® BoneCeramic, Bio-Oss®, Puros®, and autologous bone. A randomized controlled clinical trial

OBJECTIVE

This investigation focused on a comparison of clinical and histological characteristics after sinus floor augmentation with biphasic calcium phosphate (BCP, Straumann BoneCeramic(®) ), anorganic bovine bone (ABB, Geistlich Bio-Oss(®) ), mineralized cancellous bone allograft (MCBA, Zimmer Puros(®) ), or autologous bone (AB).

MATERIALS AND METHODS

Thirty consecutive patients with a posterior edentulous maxillary situation and a vertical bone height less than or equal to 4 mm were included in this study. A two-stage procedure was carried out. After augmentation of the maxillary sinus with ABB, BCP, MCBA, or AB followed by a healing period of 5 months, biopsies were taken with simultaneous implant placement. The samples were analyzed using microradiography and histology.

RESULTS

Ninety-four implants were placed in the augmented positions and 53 bone biopsies were taken and evaluated. The bone volume fraction of newly formed bone was measured as 30.28 ± 2.16% for BCP, 24.9 ± 5.67% for ABB, 41.74 ± 2.1% for AB, and 35.41 ± 2.78% for MCBA with significant increases in bone volume of AB vs. BCP and ABB, and MCBA vs. ABB samples. Significantly different residual bone substitute material was measured as 15.8 ± 2.1% in the BCP group and 21.36 ± 4.83% in the ABB group.

CONCLUSION

As it provides the highest rate of de novo bone formation, AB can be considered to remain the gold standard in sinus floor augmentation. All tested control materials showed comparable results and are suitable for maxillary sinus augmentation.

Advances in meniscal tissue engineering

Meniscal tears are the most common knee injuries and have a poor ability of healing. In the last few decades, several techniques have been increasingly used to optimize meniscal healing. Current research efforts of tissue engineering try to combine cell-based therapy, growth factors, gene therapy, and reabsorbable scaffolds to promote healing of meniscal defects. Preliminary studies did not allow to draw definitive conclusions on the use of these techniques for routine management of meniscal lesions. We performed a review of the available literature on current techniques of tissue engineering for the management of meniscal tears.

Multi-composite bioactive osteogenic sponges featuring mesenchymal stem cells, platelet-rich plasma, nanoporous silicon enclosures, and Peptide amphiphiles for rapid bone regeneration

A novel bioactive sponge was created with a composite of type I collagen sponges or porous poly(ε-caprolactone) (PCL) scaffolds, platelet-rich plasma (PRP), BMP2-loaded nanoporous silicon enclosure (NSE) microparticles, mineralizing peptide amphiphiles (PA), and mesenchymal stem cells (MSC). Primary MSC from cortical bone (CB) tissue proved to form more and larger colony units, as well as produce more mineral matrix under osteogenic differentiation, than MSC from bone marrow (BM). Coating pre-treatments were optimized for maximum cell adhesion and mineralization, while a PRP-based gel carrier was created to efficiently deliver and retain MSC and microparticles within a porous scaffold while simultaneously promoting cell recruitment, proliferation, and angiogenesis. Components and composite sponges were evaluated for osteogenic differentiation in vitro. Osteogenic sponges were loaded with MSC, PRP, PA, and NSE and implanted subcutaneously in rats to evaluate the formation of bone tissue and angiogenesis in vivo. It was found that the combination of a collagen sponge with CB MSC, PRP, PA, and the BMP2-releasing NSE formed the most bone and was most vascularized by four weeks compared to analogous composites featuring BM MSC or PCL or lacking PRP, PA, and NSE. This study indicates that CB MSC should be considered as an alternative to marrow as a source of stem cells, while the PRP-PA cell and microparticle delivery system may be utilized for diverse tissue engineering applications.

Reduction of bone resorption by the application of platelet-rich plasma (PRP) in bone grafting of the alveolar cleft

OBJECTIVE

We evaluated the effectiveness of platelet-rich plasma (PRP) on the regeneration of autogenous cancellous bone and marrow grafted in the alveolar cleft.

DESIGN

Twenty patients with alveolar clefts were examined; 6 were the control group and received cancellous bone and marrow grafts without PRP, while the remaining 14 comprised the PRP group and received grafts with PRP. Prior to surgery, 50 ml of blood was withdrawn and 5 ml of PRP gel produced through centrifugal separation. The bone graft mixed with PRP was then packed into the alveolar cleft. Postoperative bone density was assessed as the aluminium-equivalent value on occlusal X-ray films in a qualitative analysis. Quantitative evaluation of regenerated bone was made with computed tomography and panoramic radiographs at 1 month, 6 months and 1 year after surgery.

RESULTS

Satisfactory bone bridging formation was observed in all patients without any complications. The bone density of the PRP group was lower than that of the control group at 1 week, but the same after 1 month. The added PRP reduced the resorption of regenerated bone postoperatively.

CONCLUSION

Autogenous cancellous bone grafting with PRP, which significantly reduces postoperative bone resorption, is a reliable technique for alveolar bone grafting of cleft patients.

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.

Inorganic pyrophosphatase induces type I collagen in osteoblasts

INTRODUCTION

The physiologic selectivity of calcification in bone tissue reflects selective co-expression by osteoblasts of fibrillar collagen I and of tissue nonspecific alkaline phosphatase (TNAP), which hydrolyzes the calcification inhibitor pyrophosphate (PP(i)) and generates phosphate (P(i)). Humans and mice deficient in the PP(i)-generating ecto-enzyme NPP1 demonstrate soft tissue calcification, occurring at sites of extracellular matrix expansion. Significantly, the function in osteoblasts of cytosolic inorganic pyrophosphatase (abbreviated iPP(i)ase), which generates P(i) via PP(i) hydrolysis with neutral pH optimum, remains unknown. We assessed iPP(i)ase in Enpp1(-/-) and wild type (WT) mouse osteoblasts and we tested the hypothesis that iPP(i)ase regulates collagen I expression.

METHODS

We treated mouse calvarial osteoblasts with ascorbate and beta-glycerol phosphate to promote calcification, and we assessed cytosolic P(i) and PP(i) levels, sodium-dependent P(i) uptake, Pit-1 P(i) co-transporter expression, and iPP(i)ase and TNAP activity and expression. We also assessed the function of transfected Ppa1 in osteoblasts.

RESULTS

Inorganic pyrophosphatase but not TNAP was elevated in Enpp1(-/-) calvariae in situ. Cultured primary Enpp1(-/-) calvarial osteoblasts demonstrated increased calcification despite flat TNAP activity rather than physiologic TNAP up-regulation seen in WT osteoblasts. Despite decreased cytosolic PP(i) in early culture, Enpp1(-/-) osteoblasts maintained cytosolic P(i) levels comparable to WT osteoblasts, in association with increased iPP(i)ase, enhanced sodium-dependent P(i) uptake and expression of Pit-1, and markedly increased collagen I synthesis. Suppression of collagen synthesis in Enpp1(-/-) osteoblasts using 3,4-dehydroproline markedly suppressed calcification. Last, transfection of Ppa1 in WT osteoblasts increased cytosolic P(i) and decreased cytosolic but not extracellular PP(i), and induced both collagen I synthesis and calcification.

CONCLUSIONS

Increased iPP(i)ase is associated with "P(i) hunger" and increased calcification by NPP1-deficient osteoblasts. Furthermore, iPP(i)ase induces collagen I at the levels of mRNA expression and synthesis and, unlike TNAP, stimulates calcification by osteoblasts without reducing the extracellular concentration of the hydroxyapatite crystal inhibitor PP(i).

Platelet-rich plasma: a literature review

Platelet-rich plasma (PRP) is an autologous concentration of platelets in concentrated plasma, which is extensively used to promote soft and hard tissue healing. The significance behind its use refers to the abundance of growth factors present in a well-prepared PRP concentrate. These growth factors enhance the rate and quality of wound healing by different mechanisms. The objective of this review article is to explain the biological aspect of hard and soft tissue healing by application of PRP in conjunctions with its molecular basis.

Influence of the proportion of particulate autogenous bone graft/platelet-rich plasma on bone healing in critical-size defects: an immunohistochemical analysis in rat calvaria

This immunohistochemical analysis evaluated the influence of the proportion of particulate autogenous bone (AB) graft/platelet-rich plasma (PRP) on bone healing in surgically created critical-size defects (CSD) in rat calvaria. 25 rats were divided into 5 groups: C (control), AB, AB/PRP-50, AB/PRP-100 and AB/PRP-150. A 5 mm diameter critical-size defect was created in the calvarium of each animal. In Group C, defect was filled by blood clot only. In Group AB, defect was filled with AB graft. In Groups AB/PRP-50, AB/PRP-100 and AB/PRP-150, defects were filled with AB graft combined with 50, 100 and 150 microl of PRP, respectively. Animals were euthanized at 30 days post-operative. Osteocalcin (OC) and osteopontin (OP) immunohistochemical staining were performed. OP-positive and OC-positive cells were quantified. The amount of vital bone (VBA) and remaining bone graft particles (RPA) were calculated as percentage of the total area of the original defect. Data were statistically analyzed (ANOVA, Tukey, p<0.05). Group AB/PRP-100 presented a significantly higher number of OP-positive cells than groups C, AB/PRP-50 and AB/PRP-150 (p<0.05) and also a significantly higher number of OC-positive cells than all of the other groups (p<0.05). The number of OP-positive cells in Group AB/PRP-150 was significantly lower than in Group AB (p<0.05). Statistically significant differences were not found between groups with regard to either VBA or RPA (p>0.05). However, clear trends were indicated by an increase in VBA in Group AB/PRP-100 when compared to groups C, AB and AB/PRP-150 and an increase in RPA in Group AB/PRP-150 when compared to groups AB, AB/PRP-50 and AB/PRP-100. The proportion AB graft/PRP seems to influence bone healing in CSD in rat calvaria. The highest expression of osteocalcin and osteopontin, and thus the most developed healing, was found in Group AB/PRP-100 indicating that there may be an optimal proportion beyond which increasing the concentration PRP is deleterious.

Bone regenerative properties of rat, goat and human platelet-rich plasma

To explore the reported contradictory osteogenic capacity of platelet-rich plasma (PRP), the aim of the study was to examine and compare the bone regenerative effect of: PRPs of different species (rat, goat, human); human bone graft (HB) vs. HB combined with human PRP (HB+hPRP); and HB+hPRP vs. synthetic hydroxyapatite-tricalcium phosphate bone substitute combined with hPRP (HA/TCP+hPRP). For this purpose, 72 implants, divided into 6 groups (n=6) were inserted in critical-sized defects of immunodeficient rats. After 2 and 4 weeks, descriptive and quantitative histological, and micro-CT analyses were performed on the specimens. Rat and goat PRP combined with HA/TCP did not enhance bone regeneration compared with HA/TCP. In contrast, human PRP combined with HA/TCP resulted in significantly increased bone fill compared to HA/TCP. The addition of human PRP to human bone graft increased significantly the amount of newly formed bone after 2 weeks. HB+hPRP demonstrated enhanced bone healing compared to HA/TCP+hPRP. In conclusion, rat and goat PRP had no effect on bone formation. Human PRP improved the initial osteogenic response of human bone graft. Human PRP combined with human bone graft had better osteogenic capacity than human PRP combined with synthetic bone substitute.

Interaction of platelet-rich concentrate with bone graft materials: an in vitro study

OBJECTIVE

Platelet-rich concentrate (PRC) is in routine use for orthopaedic and maxilofacial surgery and is frequently combined with bone graft materials to fill bony defects and enhance healing. Numerous studies have been performed investigating the efficacy of PRC to enhance bone healing in which a variety of graft materials have been combined with varying degrees of success. Here, we sought to determine the effect of combining PRC with different graft materials on human bone marrow stromal cell (hBMSC) proliferation, osteoblastic differentiation, and bone formation.

METHODS

Our central hypothesis is that PRC is not a true osteogenic agent but rather is osteopromotive, with cell fate determination being dependent on additional signals derived from the microenvironment. Experiments were performed with low passage (maximum 3) hBMSCs that were maintained in the presence of ascorbic acid-2-phosphate and beta-glycerol phosphate. Dexamethasone was excluded from these studies. PRC and graft materials were retained within well inserts and clotted by addition of bovine thrombin. Cell proliferation was determined by DNA content, osteoblastic commitment, and differentiation by alkaline phosphatase activity and matrix mineralization.

RESULTS

Combining PRC with the graft materials increased proliferation above that seen with the graft materials alone; however, only demineralized bone matrix (DBM) and allograft were capable of increasing proliferation above that seen with PRC alone. The increased proliferation observed in the presence of PRC coincided with decreased normalized alkaline phosphatase activity, suggesting decreased osteoblastic differentiation. However, at later time points, PRC increased mineralization compared with DBM, collagen, or beta tricalcium phosphate alone. When compared with PRC alone, addition of DBM or allograft decreased mineralization. Collagen gave rise to a small increase in mineralization, whereas beta tricalcium phosphate yielded the same level of mineralization as PRC alone.

CONCLUSIONS

The data obtained from these in vitro investigations demonstrate that the cellular responses induced by PRC and bone graft materials in hBMSC can be significantly (positively or negatively) modified by adding the agents in combination. These in vitro data highlight the need to consider the potential interaction between biologic agents when added in combination.

Platelet-rich concentrate supports human mesenchymal stem cell proliferation, bone morphogenetic protein-2 messenger RNA expression, alkaline phosphatase activity, and bone formation in vitro: a mode of action to enhance bone repair

OBJECTIVE

Platelet-rich concentrate (PRC) is an autologous growth factor preparation that is in routine use for orthopaedic and maxillofacial surgery. However, there are little data available describing the cellular and molecular mechanisms by which PRC enhances the healing response in an osseous environment. The aim of this study was to identify cellular and molecular events that are modulated in human mesenchymal stem cells (hMSCs) in response to exposure to human PRC generated by a novel filtration-based device (CAPTION, Smith & Nephew Inc).

METHODS

PRC and serum were prepared from blood donated by 11 volunteers. Growth factor content and release from PRC were determined by enzyme-linked immunosorbent assay. Cell proliferation was quantified by DNA content and osteoblastic differentiation by alkaline phosphatase expression and mineralized nodule formation. Real-time reverse transcription-polymerase chain reaction analysis was used to determine the early molecular pathways regulated in hMSCs by PRC.

RESULTS

The results obtained confirm previous in vitro and in vivo observations demonstrating that PRC enhances hMSC proliferation. Furthermore, our data suggest that when added as a clot, PRC induces an earlier onset of proliferation compared with serum without leading to cell overgrowth and the inhibition of cell differentiation. At the molecular level, PRC treatment stimulated a transient enhancement of bone morphogenetic protein-2 messenger RNA that peaked after 12 hours and induced an earlier and a sustained increase in the key osteogenic transcription factor RUNX2. By 3 days of treatment, PRC enhanced alkaline phosphatase activity more than 2-fold compared with donor-matched serum, and at 23 days, the increase in osteoblastic commitment translated to enhanced calcified matrix deposition.

CONCLUSIONS

Taken together, the data presented here suggest that treatment of hMSC with clotted PRC, in an osteoinductive environment, enhances osteoblastic commitment and bone formation. Furthermore, these data indicate that the enhanced osteogenesis seen in the presence of PRC cannot be explained solely by enhanced cell proliferation, suggesting that PRC modulates a number of cell and molecular pathways to promote bone formation.

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.