An Innovative, Centrifugation-free Method to Prepare Human Platelet Mediator Concentrates Showing Activities Comparable to Platelet-rich Plasma .

UNLABELLED: Slow-healing wounds benefit considerably from treatment with platelet-rich plasma (PrP). The drawback of using PrP is its laborious preparation, which requires expensive technical equipment (centrifuges) and well-trained personnel. METHODS: The authors' new method overcomes these issues and provides the practitioner with an innovative tool to freshly prepare a platelet mediator mix with PrP's known biological activities, but is much simpler to obtain. This is achieved by employing the sedimentation of a blood sample at regular gravity (no centrifuge necessary) in the presence of an anti-coagulant and a sedimentation accelerator. Thereafter, the supernatant containing the platelets is concentrated on a unique filter, which causes these platelets to release their mediators (different biologically active molecules resembling the substance mix that is released by the platelets upon degranulation). This solution is eluted from the filter, providing a sterile-filtered, enriched fraction of biologically active mediators (TGF-ß, PDGF, IGF-1, etc.), most of which are active in wound healing disorders. RESULTS: This preparation triggers in-vitro proliferation of fibroblasts and osteoblasts, the secretion of IL-6 by osteoblasts, and differentiation of fibroblasts into cells with an endothelial morphology resembling cells during angiogenesis. CONCLUSION: By providing the practioner a sterile concentrate of a whole range of autologous platelet mediators within 1 hour, this new method has the potency to become a substitute of PrP in wound-healing therapy. PMC (platelet mediator concentrate) eases the manufacturing of such preparations, thereby making them not only more widely applicable, but also reducing treatment costs.

Release of Antibiotics Out of a Moldable Collagen-ß-Tricalciumphosphate-Composite Compared to Two Calcium Phosphate Granules.

Bacterial bone infections after revision surgeries and diseases, like osteomyelitis, are still a challenge with regard to surgical treatments. Local bone infections were treated with antibiotics directly or by controlled drug-releasing scaffolds, like polymethylmethacrylate (PMMA) spheres, which have to be removed at a later stage, but there is a risk of a bacterial contamination during the removement. Therefore, biomaterials loaded with antibiotics for controlled release could be the method of choice: The biomaterials degrade during the drug release, therefore, there is no need for a second surgery to remove the drug eluting agent. Even non-resorbable bone materials are available (e.g., hydroxyapatite (HA)) or resorbable bone graft materials (e.g., beta-tricalcium phosphate (ß-TCP)) that will be replaced by newly formed bone. Composite materials with organic additives (e.g., collagen) supports the handling during surgery and enhances the drug loading capacity, as well as the drug releasing time. The purpose of this study was to investigate the loading capacity and the release rate of Vancomycin and Gentamicin on TCP and HA granules in the shape of a degradable scaffold compared to composite materials from TCP mixed with porcine collagen. Its antibacterial efficacy to a more elementary drug with eluting in aqueous solution was examined. The loading capacity of the biomaterials was measured and compared according to the Minimum Inhibition Concentration (MIC) and the Minimum Biofilm Eradication Concentration (MBEC) of a bacterial biofilm after 24 h aging. Antibiotic elution and concentration of gentamycin and vancomycin, as well as inhibition zones, were measured by using the Quantitative Microparticle Systems (QMS) immunoassays. The antibiotic concentration was determined by the automated Beckman Coulter (BC) chemistry device. For examination of the antibacterial activity, inhibition zone diameters were measured. Generally, the antibiotic release is more pronounced during the first couple of days than later. Both TCP granules and HA granules experienced a significantly decline of antibiotics release during the first three days. After the fourth day and beyond, the antibiotic release was below the detection threshold. The antibiotic release of the composite material TCP and porcine collagen declined less drastically and was still in the frame of the specification during the first nine days. There was no significant evidence of interaction effect between antibiotic and material, i.e., the fitted lines for Gentamycin and Vancomycin are almost parallel. During this first in vitro study, ß-TCP-Collagen composites shows a significantly higher loading capacity and a steadily release of the antibiotics Gentamycin and Vancomycin, compared to the also used TCP and HA Granules.

Effect of silicon-doped calcium phosphate bone grafting materials on bone regeneration and osteogenic marker expression after implantation in the ovine scapula.

Compared to the currently clinically available bone grafting materials for alveolar ridge augmentation, there is a great demand for bioactive bone substitutes with higher resorbability, which enhance osteogenesis at the same time. This has prompted the development of a silicon-doped rapidly resorbable calcium alkali orthophosphate (Si-CAOP) and silicon-doped ß-tricalcium phosphate (Si-TCP). This study evaluated the effect of these two particulate graft materials as compared to the currently clinically used ß-TCP on bone formation and osteogenic marker expression after 2 weeks, 1, 3, 6, 12, and 18 months of implantation in critical size defects in the sheep scapula. Immunohistochemical analysis of collagen type I, alkaline phosphatase, and osteocalcin expression was performed on resin embedded sections. The bone and particle area fraction and the bone-biomaterial contact were determined histomorphometrically. After 2 weeks and 1 month defects grafted with Si-CAOP displayed a significantly greater bone area fraction, bone-particle-contact, osteogenic marker expression and significantly lower particle area fraction than defects grafted with Si-TCP and TCP. By 3 and 6 months all materials studied mediated excellent defect regeneration with further bone remodeling at 12 and 18 months. Taken together, Si-CAOP induced the most expeditious bone regeneration of critical size defects in the sheep scapula. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 594-614, 2019.

Injectable Bone Substitute Based on ß-TCP Combined With a Hyaluronan-Containing Hydrogel Contributes to Regeneration of a Critical Bone Size Defect Towards Restitutio ad Integrum.

In the present in vivo study, the regenerative potential of a new injectable bone substitute (IBS) composed of beta-tricalcium phosphate (ß-TCP) and hyaluronan was tested in a rabbit distal femoral condyle model. To achieve this, 2 defects of 6 mm in diameter and 10 mm in length were drilled into each femur condyle in a total of 12 animals. For each animal, 1 hole was filled with the substitute material, and the other was left empty to serve as the control. After 1, 3, and 6 months, the regenerative process was analyzed by radiography as well as by histological and histomorphometrical analysis. The results revealed that bone tissue formation took place through osteoconductive processes over time, starting from the defect borders to the center. Both the ß-TCP content and the hydrogel support bone tissue growth. The histomorphometrical measurements showed that the amount of bone formation in the experimental group was significantly higher compared with that found in the control group after 3 months (19.51 ± 5.08% vs. 1.96 ± 0.77%, P < .05) and 6 months (4.57 ± 1.56% vs. 0.23 ± 0.21%, P < .05). The application of the IBS gave a restitutio ad integrum result after 6 months and was associated with its nearly complete degradation, in contrast to the results found in the control group. In conclusion, the results of the present study demonstrate that the IBS contributes to sufficient bone regeneration by serving as a scaffold-like structure, combined with its degradation within 6 months.

Effect of a ß-TCP collagen composite bone substitute on healing of drilled bone voids in the distal femoral condyle of rabbits.

In this study, we tested the performance and biocompatibility of a composite of ß-tricalcium phosphate (ß-TCP) to collagen as a bone void filler (Cerasorb(®) Ortho Foam) in a rabbit distal femoral condyle model. ß-TCP is a completely resorbable synthetic calcium phosphate and the addition of a collagen matrix couples the osteoconductive effects of the two components. Furthermore, the malleable properties of the implant material during surgical applications for shape control will be enhanced. A critical size defect of 6 mm in diameter and 10 mm in depth was drilled into each distal femur of the rabbits. One hole was filled with the test substance and the other was left empty for control. After 1, 3, and 6 months the animals were killed and the degree of bone healing analyzed. In total, 18 animals were investigated. When the ß-TCP composite was used, histological, histomorphometric, and biomechanical evaluations revealed significantly better bone healing in terms of quantity and quality of the newly formed bone. Moreover, no signs of inflammation were observed in the animals and no allergic or foreign body reaction was noted. This suggests high biocompatibility and osteoconductivity of the investigated material to a bone void in an immune responsive species.