Comparative release of growth factors from PRP, PRF, and advanced-PRF

OBJECTIVES The use of platelet concentrates has gained increasing awareness in recent years for regenerative procedures in modern dentistry. The aim of the present study was to compare growth factor release over time from platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and a modernized protocol for PRF, advanced-PRF (A-PRF). MATERIALS AND METHODS Eighteen blood samples were collected from six donors (3 samples each for PRP, PRF, and A-PRF). Following preparation, samples were incubated in a plate shaker and assessed for growth factor release at 15 min, 60 min, 8 h, 1 day, 3 days, and 10 days. Thereafter, growth factor release of PDGF-AA, PDGF-AB, PDGF-BB, TGFB1, VEGF, EGF, and IGF was quantified using ELISA. RESULTS The highest reported growth factor released from platelet concentrates was PDGF-AA followed by PDGF-BB, TGFB1, VEGF, and PDGF-AB. In general, following 15-60 min incubation, PRP released significantly higher growth factors when compared to PRF and A-PRF. At later time points up to 10 days, it was routinely found that A-PRF released the highest total growth factors. Furthermore, A-PRF released significantly higher total protein accumulated over a 10-day period when compared to PRP or PRF. CONCLUSION The results from the present study indicate that the various platelet concentrates have quite different release kinetics. The advantage of PRP is the release of significantly higher proteins at earlier time points whereas PRF displayed a continual and steady release of growth factors over a 10-day period. Furthermore, in general, it was observed that the new formulation of PRF (A-PRF) released significantly higher total quantities of growth factors when compared to traditional PRF. CLINICAL RELEVANCE Based on these findings, PRP can be recommended for fast delivery of growth factors whereas A-PRF is better-suited for long-term release.

Recombinant Human Bone Morphogenetic Protein 9 (rhBMP9) Induced Osteoblastic Behaviour on a Collagen Membrane Compared With rhBMP2

BACKGROUND Bone morphogenetic protein 9 (BMP9) has previously been characterized as one of the most osteogenic growth factors of the BMP-family, however, up until now, these experiments have only been demonstrated using adenovirus-transfection experiments (gene therapy). With the recent development of recombinant human (rh)BMP9, the aim of the present study was to investigate its osteopromotive potential versus rhBMP2 when loaded onto a collagen membrane. METHODS ST2 stromal bone marrow cells were seeded onto 1)control; 2)rhBMP2-low(10ng/ml); 3)rhBMP2-high(100ng/ml); 4)rhBMP9-low(10ng/ml); and 5)rhBMP9-high(100ng/ml) porcine collagen membranes. Groups were then compared for cell adhesion at 8 hours, cell proliferation at 1, 3 and 5 days real-time PCR at 3 and 14 days for genes encoding Runx2, alkaline phosphatase(ALP) and bone sialoprotein(BSP) at 3 and 14 days and alizarin red staining at 14 days. RESULTS While rhBMP2 and rhBMP9 demonstrated little effects on cell attachment and proliferation, pronounced increases were observed on osteoblast differentiation. It was found that all groups significantly induced ALP mRNA levels at 3 days and BSP levels at 14 days, however rhBMP9-high demonstrated significantly higher values when compared to all other groups for ALP levels (5-fold increase at 3 days and 2-fold increase at 14 days). Alizarin red staining further revealed that both concentrations of rhBMP9 induced up to 3-fold more staining when compared to rhBMP2. CONCLUSION These results indicate that the combination of collagen membranes with rhBMP9 significantly induced significantly higher ALP mRNA expression and alizarin red staining when compared to rhBMP2. These findings suggest that rhBMP9 may be a suitable growth factor for future regenerative procedures in bone biology.

OsteoMacs: Key players around bone biomaterials.

Osteal macrophages (OsteoMacs) are a special subtype of macrophage residing in bony tissues. Interesting findings from basic research have pointed to their vast and substantial roles in bone biology by demonstrating their key function in bone formation and remodeling. Despite these essential findings, much less information is available concerning their response to a variety of biomaterials used for bone regeneration with the majority of investigation primarily focused on their role during the foreign body reaction. With respect to biomaterials, it is well known that cells derived from the monocyte/macrophage lineage are one of the first cell types in contact with implanted biomaterials. Here they demonstrate extremely plastic phenotypes with the ability to differentiate towards classical M1 or M2 macrophages, or subsequently fuse into osteoclasts or multinucleated giant cells (MNGCs). These MNGCs have previously been characterized as foreign body giant cells and associated with biomaterial rejection, however more recently their phenotypes have been implicated with wound healing and tissue regeneration by studies demonstrating their expression of key M2 markers around biomaterials. With such contrasting hypotheses, it becomes essential to better understand their roles to improve the development of osteo-compatible and osteo-promotive biomaterials. This review article expresses the necessity to further study OsteoMacs and MNGCs to understand their function in bone biomaterial tissue integration including dental/orthopedic implants and bone grafting materials.

Effect of Enamel Matrix Derivative Liquid on Osteoblast and Periodontal Ligament Cell Proliferation and Differentiation.

BACKGROUND Enamel matrix derivatives (EMDs) have been used clinically for more than a decade for the regeneration of periodontal tissues. The aim of the present study is to analyze the effect on cell growth of EMDs in a gel carrier in comparison to EMDs in a liquid carrier. EMDs in a liquid carrier have been shown to adsorb better to bone graft materials. METHODS Primary human osteoblasts and periodontal ligament (PDL) cells were exposed to EMDs in both gel and liquid carriers and compared for their ability to induce cell proliferation and differentiation. Alizarin red staining and real-time polymerase chain reaction for expression of genes encoding collagen 1, osteocalcin, and runt-related transcription factor 2, as well as bone morphogenetic protein 2 (BMP2), transforming growth factor (TGF)-β1, and interleukin (IL)-1β, were assessed. RESULTS EMDs in both carriers significantly increased cell proliferation of both osteoblasts and PDL cells in a similar manner. Both formulations also significantly upregulated the expression of genes encoding BMP2 and TGF-β1 as well as decreased the expression of IL-1β. EMDs in the liquid carrier further retained similar differentiation potential of both osteoblasts and PDL cells by demonstrating increased collagen and osteocalcin gene expression and significantly higher alizarin red staining. CONCLUSIONS The results from the present study indicate that the new formulation of EMDs in a liquid carrier is equally as potent as EMDs in a gel carrier in inducing osteoblast and PDL activity. Future study combining EMDs in a liquid carrier with bone grafting materials is required to further evaluate its potential for combination therapies.

Characterization of a shorter recombinant polypeptide chain of bone morphogenetic protein 2 on osteoblast behaviour

BACKGROUND Recombinant bone morphogenetic protein two (rhBMP2) has been utilised for a variety of clinical applications in orthopaedic surgery and dental procedures. Despite its widespread use, concerns have been raised regarding its short half-life and transient bioactivity in vivo. Recent investigation aimed at developing rhBMP2 synthesized from a shorter polypeptide chain (108 amino acids) has been undertaken. METHODS The osteopromotive properties of BMP2 were investigated on cell behaviour. Five concentrations of rhBMP2_108 including 10, 50, 100, 200 and 500 ng/ml were compared to a commercially available rhBMP2 (100 ng/ml). Each of the working concentrations of rhBMP2_108 were investigated on MC3T3-E1 osteoblasts for their ability to induce osteoblast recruitment, proliferation and differentiation as assessed by alkaline phosphatase (ALP) staining, alizarin red staining, and real-time PCR for genes encoding ALP, osteocalcin (OCN), collagen-1 (COL-1) and Runx2. RESULTS The results demonstrate that all concentrations of rhBMP2_108 significantly improved cell recruitment and proliferation of osteoblasts at 5 days post seeding. Furthermore, rhBMP2_108 had the most pronounced effects on osteoblast differentiation. It was found that rhBMP2_108 had over a four fold significant increase in ALP activity at seven and 14 days post-seeding and the concentrations ranging from 50 to 200 ng/ml demonstrated the most pronounced effects. Analysis of real-time PCR for genes encoding ALP, OCN, COL-1 and Runx2 further confirmed dose-dependant increases at 14 days post-seeding. Furthermore, alizarin red staining demonstrated a concentration dependant increase in staining at 14 days. CONCLUSION The results from the present study demonstrate that this shorter polypeptide chain of rhBMP2_108 is equally as bioactive as commercially available rhBMP2 for the recruitment of progenitor cells by facilitating their differentiation towards the osteoblast lineage. Future in vivo study are necessary to investigate its bioactivity.

Certain letters of James Howell : selected from the Familiar letters as first published between 1645 & 1655.

Text within double red lines.

The new forest.

Mode of access: Internet.

The letters of Philip Dormer Stanhope, earl of Chesterfield, with the characters.

The letters written by Chesterfield to his son prior to October, 1739, and a few subsequent ones are omitted in this edition. Includes five letters not printed previously.

An address on national aid to education,

"Reprinted from Circulars of information, no. 2, 1879."

Ballads of Down /

"Opinions of the Press" bound in at back (19 p.).

School hygiene,

Bibliography: p. 253-255.

The arithmetic of the gold and silversmith; prepared for the use of jewelers, founders, merchants, etc., especially for those engaged in the conversion and alloying of gold or other metals, the mixing of various substances, etc.,

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Anglo-Saxon and Old English vocabularies

v. 1. Vocabularies.--v. 2. Indices.

The rhythm way to family happiness; a lifetime reference for the use of the rhythm method,

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An evaluation of the problems of sanitary sewer system design; final report of the Residential Sewerage Research Project to the Federal Housing Administration

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