The in vitro effect of different PRP concentrations on osteoblasts and fibroblasts

Objectives:The aim of this study was to assess the biological rationale for the use of platelet-rich plasma (PRP) by evaluating the effect of different concentrations of PRP on osteoblasts (OB) and fibroblasts (FB) function in vitro. Materials and methods:PRP was obtained from volunteer donors using standard protocols. Primary human cultures of oral FBs and OBs were exposed to both activated and non-activated plasma as well as various concentrations of PRP (2.5 x, 3.5 x and max (4.2-5.5 x)). Cell proliferation was evaluated after 24 and 72 h using an MTT proliferation assay. Production of osteocalcin (OCN), osteoprotegerin (OPG) and transforming growth factor beta 1 (TGF-beta 1) was evaluated in OB after 24 and 72 h. Statistical analysis was performed using one-way ANOVA. Results:PRP-stimulated cell proliferation in both OBs and FBs. The effect of different PRP concentrations on cell proliferation was most notable at 72 h. The maximum effect was achieved with a concentration of 2.5 x, with higher concentrations resulting in a reduction of cell proliferation. Upregulation of OCN levels and downregulation of OPG levels were noted with increasing PRP concentrations at both 24 and 72 h. TGF-beta 1 levels were stimulated by increasing concentrations of PRP, with the increased levels being maintained at 72 h. Conclusions:PRP preparations exert a dose-specific effect on oral FBs and OBs. Optimal results were observed at a platelet concentration of 2.5 x, which was approximately half of the maximal concentrate that could be obtained. Increased concentrations resulted in a reduction in proliferation and a suboptimal effect on OB function. Hence, different PRP concentrations may have an impact on the results that can be obtained in vivo

Local delivery of hydrogel encapsulated vascular endothelial growth factor for the prevention of medication-related osteonecrosis of the jaw

The anti-angiogenic effects of bisphosphonates have been hypothesized as one of the major etiologic factors in the development of medication-related osteonecrosis of the jaw (MRONJ), a severe debilitating condition with limited treatment options. This study evaluated the potential of a gelatine-hyaluronic acid hydrogel loaded with the angiogenic growth factor, vascular endothelial growth factor (VEGF), as a local delivery system to aid in maintaining vascularization in a bisphosphonate-treated (Zoledronic Acid) rodent maxillary extraction defect. Healing was assessed four weeks after implantation of the VEGF-hydrogel into extraction sockets. Gross examination and histological assessment showed that total osteonecrosis and inflammatory infiltrate was significantly reduced in the presence of VEGF. Also, total vascularity and specifically neovascularization, was significantly improved in animals that received VEGF hydrogel. Gene expression of vascular, inflammatory and bone specific markers within the defect area were also significantly altered in the presence of VEGF. Furthermore, plasma cytokine levels were assessed to determine the systemic effect of locally delivered VEGF and showed similar outcomes. In conclusion, the use of locally delivered VEGF within healing extraction sockets assists bone healing and prevents MRONJ via a pro-angiogenic and immunomodulatory mechanism

Accelerated wound healing phenotype in Interleukin 12/23 deficient mice

Background: The concept that a strong inflammatory response involving the full complement of cytokines and other mediators is critical for unimpaired healing has been challenged by wound healing studies using transgenic and knockout (KO) mice. The present study explored the effect of abrogation of the p40 subunit, which is shared by the pro-inflammatory cytokines interleukin (IL)-12 and IL-23, on wound closure of excisional oral mucosal wounds

Novel polycaprolactone/hydroxyapatite nanocomposite fibrous scaffolds by direct melt-electrospinning writing

Melt electrospinning writing (MEW) using an automated stage has recently been developed as a direct additive manufacturing method for the fabrication of orderly, precise and complex porous 3D fibrous structures that can promote cell infiltration and growth. The further incorporation of inorganic particles within fibrous scaffolds is desirable in order to enhance bioactivity, however this remains challenging with the MEW fabrication process. To address this challenge, flexible, osteoconductive, medical grade polycaprolactone (m-PCL) - hydroxyapatite (HAp) composite 3D fibrous structures with high porosity (96–98%) and fully interconnected pore architectures were fabricated using MEW under precisely controlled parameters. The physical properties of these 3D fibrous composite scaffolds including fibre size, mechanical characteristics, and in vitro degradation rate were investigated. The results showed that the composite m-PCL/HAp fibrous scaffolds degraded in an alkaline environment at 37 °C faster than plain m-PCL and provided a favourable platform for the infiltration and growth of human osteoblasts. Moreover, confocal imaging confirmed that the scaffolds contained HAp nano-particles (NPs) which induced a more homogeneous distribution of cells within the scaffold particularly after 7 days of culture. Osteoblast activity and viability in the m-PCL/HAp composite scaffolds indicated a favourable cell/material interaction, suggesting great potential for use in mineralised tissue reconstruction / regeneration applications

Assessment of static and perfusion methods for decellularization of PCL membrane-supported periodontal ligament cell sheet constructs

Decellularization aims to harness the regenerative properties of native extracellular matrix. The objective of this study was to evaluate different methods of decellularization of periodontal ligament cell sheets whilst maintaining their structural and biological integrity.Human periodontal ligament cell sheets were placed onto melt electrospun polycaprolactone (PCL) membranes that reinforced the cell sheets during the various decellularization protocols. These cell sheet constructs (CSCs) were decellularized under static/perfusion conditions using a) 20 mM ammonium hydroxide (NH4OH)/Triton X-100, 0.5% v/v; and b) sodium dodecyl sulfate (SDS, 0.2% v/v), both +/- DNase besides Freeze-thaw (F/T) cycling method. CSCs were assessed using a collagen quantification assay, immunostaining and scanning electron microscopy. Residual fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were assessed with Bio-plex assays.DNA removal without DNase was higher under static conditions. However, after DNase treatment, there were no differences between the different decellularization methods with virtually 100% DNA removal. DNA elimination in F/T was less efficient even after DNase treatment. Collagen content was preserved with all techniques, except with SDS treatment. Structural integrity was preserved after NH4OH/Triton X-100 and F/T treatment, while SDS altered the extracellular matrix structure. Growth factor amounts were reduced after decellularization with all methods, with the greatest reduction (to virtually undetectable amounts) following SDS treatment, while NH4OH/Triton X-100 and DNase treatment resulted in approximately 10% retention.This study showed that treatment with NH4OH/Triton X-100 and DNase solution was the most efficient method for DNA removal and the preservation of extracellular matrix integrity and growth factors retention

Optimising degradation and mechanical performance of additively manufactured biodegradable Fe–Mn scaffolds using design strategies based on triply periodic minimal surfaces

Additively manufactured lattices based on triply periodic minimal surfaces (TPMS) have attracted significant research interest from the medical industry due to their good mechanical and biomorphic properties. However, most studies have focussed on permanent metallic implants, while very little work has been undertaken on manufacturing biodegradable metal lattices. In this study, the mechanical properties and in vitro corrosion of selective laser melted Fe–35%Mn lattices based on gyroid, diamond and Schwarz primitive unit-cells were comprehensively evaluated to investigate the relationships between lattice type and implant performance. The gyroid-based lattices were the most readily processable scaffold design for controllable porosity and matching the CAD design. Mechanical properties were influenced by lattice geometry and pore volume. The Schwarz lattices were stronger and stiffer than other designs with the 42% porosity scaffold exhibiting the highest combination of strength and ductility, while diamond and gyroid based scaffolds had lower strength and stiffness and were more plastically compliant. The corrosion behaviour was strongly influenced by porosity, and moderately influenced by geometry and geometry-porosity interaction. At 60% porosity, the diamond lattice displayed the highest degradation rate due to an inherently high surface area-to-volume ratio. The biodegradable Fe–35Mn porous scaffolds showed a good cytocompatibility to primary human osteoblasts cells. Additive manufacturing of biodegradable Fe–Mn alloys employing TPMS lattice designs is a viable approach to optimise and customise the mechanical properties and degradation response of resorbable implants toward specific clinical applications for hard tissue orthopaedic repair

The effect of systemic antibiotics on clinical and patient‐reported outcome measures of oral implant therapy with simultaneous guided bone regeneration

Publisher's version (útgefin grein)Objectives: The aim of the present superiority study was to determine the effect of systemic antibiotics primarily on patient-reported outcome measures (PROMs) and post-surgical complications in patients undergoing oral implant therapy with simultaneous guided bone regeneration (GBR). Materials and Methods: A total of 236 medically and periodontally healthy patients received oral implants with simultaneous GBR at seven centres. Pre-operative antibiotics of 2 g amoxicillin were prescribed to the test group 1 hr prior to surgery and 500 mg thrice daily on days 1–3 after surgery. The control group was given a placebo. Group allocation was performed randomly. Primary outcome variables were PROMs recorded as visual analogue scale scores assessed on days 1–7 and 14 on pain, swelling, haematoma and bleeding. Post-operative complications as secondary outcome variables were examined at 1, 2, 4 and 12 weeks from surgery. Chi-square tests and repeated measures of analysis of variance (ANOVA) were performed for statistical evaluation. Results: No statistically significant differences (p >.05) between the two groups were detected for the evaluated PROMs. The same was noted with respect to post-surgical complications. Four implants were lost—three in the test group and one in the control group. Conclusion: In this trial, systemic antibiotics did not provide additional benefits to PROMs, nor the prevention of post-surgical complications in medically and periodontally healthy patients undergoing oral implant therapy with simultaneous GBR. However, further studies with larger sample sizes are still required to support the clinical outcomes of this study.This study has been supported by a research grant of the ITI Foundation (ITI Grant‐No: No. 962_2013). Further, we want to thank the Geistlich AG, Wolhusen, Switzerland, for providing bone substitutes and collagen membranes (Bio‐Oss® and Bio‐Gide®); Medochemie Limassol, Cyprus, for providing the study medication; and the Straumann AG (Basel, Switzerland) for granting a 50% discount on all the implant materials used in the presented study. The co‐operation of the staff of the centres involved in the study is highly appreciated: (1) Peking University, School of Stomatology, Beijing PR China (2) Medical University Graz, University Clinic of Dental Medicine & Oral Health, Department of Oral Surgery and Orthodontics, Graz Austria (3) Griffith University, Gold Coast, School of Dentistry and Oral Health, Queensland, Australia (4) The University of Hong Kong, Faculty of Dentistry, Hong Kong SAR PR China (5) University of Iceland, Faculty of Odontology, Reykjavik, Iceland (6) Shanghai Jiao Tong University, Shanghai Ninth People's Hospital, Department of Implant Dentistry, Shanghai PR China (7) National Dental Centre Singapore, SingaporePeer Reviewe

Early osteogenic response of osteoprogenitor cells on modified titanium implant surfaces leads to improved osteogenesis

Background: Implant surface micro-roughness and hydrophilicity are known to improve the osteogenic differentiation potential of osteoprogenitor cells. This study was aimed to determine whether topographically and chemically modified titanium implant surfaces stimulate an initial osteogenic response in osteoprogenitor cells, which leads to their improved osteogenesis. ----- ----- Methods: Statistical analysis of microarray gene expression profiling data available from studies (at 72 hours) on sand-blasted, large grit acid etched (SLA) titanium surfaces was performed. Subsequently, human osteoprogenitor cells were cultured on SLActive (hydrophilic SLA), SLA and polished titanium surfaces for 24 hours, 3 days and 7 days. The expression of BMP2, BMP6, BMP2K, SP1, ACVR1, FZD6, WNT5A, PDLIM7, ITGB1, ITGA2, OCN, OPN, ALP and RUNX2 were studied using qPCR. ----- ----- Results: Several functional clusters related to osteogenesis were highlighted when genes showing statistically significant differences (from microarray data at 72 hours) in expression on SLA surface (compared with control surface) were analysed using DAVID (online tool). This indicates that differentiation begins very early in response to modified titanium surfaces. At 24 hours, ACVR1 (BMP pathway), FZD6 (Wnt pathway) and SP1 (TGF-β pathway) were significantly up-regulated in cultures on the SLActive surface compared to the other surfaces. WNT5A and ITGB1 also showed higher expression on the modified surfaces. Gene expression patterns on Day 3 and Day 7 did not reveal any significant differences.----- ----- Conclusion: These results suggest that the initial molecular response of osteoprogenitor cells to modified titanium surfaces may be responsible for an improved osteogenic response via the BMP and Wnt signalling pathways