Biomedical subjects

Gabor Fuerst

Publications and source records attributed to Gabor Fuerst.

8 recordsLinked to original sources

PubMed2005

Proliferation and osteogenic differentiation of cells from cortical bone cylinders, bone particles from mill, and drilling dust.

PURPOSE: The osteogenic potential of a graft is based on the parallel lines ability of cells to survive transplantation and to respond to local factors that stimulate new bone formation. Here we investigated the potential of cells that had grown out of porcine cortical bone grafts obtained by 3 preparation techniques to respond to mitogenic and osteogenic stimuli. MATERIALS AND METHODS: Bone grafts were harvested from 2 pigs. Cortical bone was taken in cylindrical form and ground in a bone mill or harvested via drilling and aspiration. RESULTS: Cell outgrowth was observed in all cortical bone cylinders, bone cylinders homogenized by mill, and 5 of 10 explants of bone dust collected upon drilling. After a 2-week culture period, the number of outgrown cells did not significantly differ among the 3 preparations. Bone cells showed increased proliferation in response to platelet-released supernatants as determined by 3 [H]-thymidine incorporation assay. When cultured under conditions that favor the expression of an osteogenic phenotype, the outgrown cells expressed alkaline phosphatase activity and transcripts of the osteoblast-specific marker osteocalcin. Individual cell preparations showed accumulation of mineral salts in their extracellular matrix. Bone cells also increased alkaline phosphatase activity in response to bone morphogenetic protein (BMP)-2, BMP-6, and BMP-7. The mitogenic and osteogenic response was obtained with cells from the mandible as well as from the maxilla, irrespective of the preparation technique. CONCLUSION: These data show that cortical bone grafts contain cells that have the ability to proliferate and differentiate into the osteogenic lineage, suggesting that these cells can contribute to bone regeneration following transplantation.

Alkaline Phosphatase↗

PubMed2005

The effect of platelet-rich plasma upon implant stability measured by resonance frequency analysis in the lower anterior mandibles.

Using a one-stage surgical protocol, a total of 34 Brånemark Mk-III Ti-Unite implants with a length of 13 mm and a diameter of 3.75 mm were inserted in 10 edentulous mandibles. Of these, seven patients received four and three patients two interforaminal implants. All implants were followed with repeated stability measurements by means of resonance frequency analysis at different time interval: 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44 days. In quadrant III platelet-rich plasma (PRP) was instilled locally before implant placement, while no PRP was added in quadrant IV to serve as control group (split-mouth design). Results showed no statistically significant difference between the two groups. Nonetheless, both groups (PRP+control) showed a highly significant reduction of the implant stability quotient (P<0.001) between days 0 and 4. However, no difference was noted between the two groups after day 4, it may be concluded that the instillation of PRP during implant placement in the lower anterior mandible did not add additional benefit.

Aged↗

PubMed2004

Effects of fibrin sealant protein concentrate with and without platelet-released growth factors on bony healing of cortical mandibular defects. An experimental study in minipigs.

In this study, the effects of fibrin sealant protein concentrate (FSPC; from the Tissucol Kit, Baxter, Vienna, Austria) with and without platelet-released growth factors (PRGF) on bony healing of cortical mandibular defects were investigated. Defects made in the facial mandibular wall of eight adult minipigs with a hollow drill were filled with FSPC alone, a mix of FSPC+PRGF or left untreated as controls. The animals were killed 4 and 8 weeks later. Specimens were processed for histology with the Donath method (1988) and stained with the Levai-Laczko stain. On histology, periosteal osteoneogenesis exceeded endosteal bone formation. No difference was seen in bone formation between FSPC alone, FSPC+PRGF and the controls at 4 and 8 weeks. On histomorphometry, there was no significant difference between the three groups in terms of the percent of newly formed bone at 4 and 8 weeks (P=0.6977). This study showed that FSPC neither increased nor decreased the amount of newly formed bone vs. controls and that the addition of PRGF had no effects on bone regeneration of cortical minipig bone at 4 and 8 weeks.

Animals↗

PubMed2004

Platelet-released supernatants increase migration and proliferation, and decrease osteogenic differentiation of bone marrow-derived mesenchymal progenitor cells under in vitro conditions.

Platelet-rich plasma is currently promoted to serve as an adjuvant for bone grafts to enhance quantity and quality of newly forming bone; however, the underlying cellular mechanisms are not fully understood. We show here that supernatants of leukocyte-depleted thrombin-activated platelets increase migration and proliferation, and decrease osteogenic differentiation of bone marrow-derived mesenchymal progenitor cells under in vitro conditions. Using neutralizing antibodies raised against platelet-derived growth factor (PDGF), the observed effects of platelet-released supernatants were diminished. The mitogenic response was also decreased when extracellular signal-regulated protein kinase (ERK) signalling was inhibited by PD98059; however, PD98059 did not reverse the effects of platelet-released supernatants on migration and osteogenic differentiation. Consistent with an ERK-mediated mitogenic activity, incubation of serum-starved mesenchymal cell progenitors with platelet-released supernatants increased phosphorylation of the kinase. Together, these observations indicate that PDGF is a key factor released upon platelet activation that can increase migration and proliferation, and decreases osteogenic differentiation of mesenchymal progenitor cells under in vitro conditions. The results further suggest that ERK signalling is required to mediate the mitogenic response to platelet-released supernatants.

Adult↗

PubMed2004

Porcine sinus mucosa holds cells that respond to bone morphogenetic protein (BMP)-6 and BMP-7 with increased osteogenic differentiation in vitro.

The aim of this in vitro study was to determine whether the sinus mucosa holds cells with an osteogenic potential. Frozen sections of sinus mucosa from three adult pigs were investigated for the expression of STRO-1, a marker of mesenchymal progenitor cells, and alkaline phosphatase activity, an enzyme expressed by cells committed to the osteogenic lineage and by mature osteoblasts. To determine their osteogenic potential, mucosa-derived cells were incubated with bone morphogenetic protein (BMP)-6 and BMP-7, and alkaline phosphatase activity, osteocalcin expression, and mineralization of the extracellular matrix was measured. We found sinus mucosa cells staining positive for STRO-1 and alkaline phosphatase activity. When sinus mucosa tissue was placed in culture, alkaline phosphatase positive cells grew out from the explants and further increased alkaline phosphatase activity in response to BMP-6 and BMP-7. The expression level of the osteoblast-specific extracellular matrix protein osteocalcin, and the amount of calcium accumulation within the extracellular matrix was also increased in response to BMPs. We conclude that the sinus mucosa holds mesenchymal progenitor cells and cells committed to the osteogenic lineage that can respond to BMP-6 and BMP-7 by an increase of their osteogenic differentiation.

Alkaline Phosphatase↗

PubMed2004

Bone formation following sinus grafting with autogenous bone-derived cells and bovine bone mineral in minipigs: preliminary findings.

Bone formation in a sinus grafted with a cell-free scaffold requires the presence of local progenitor cells that differentiate into osteoblasts. The purpose of this study was to examine the effect of culture expanded autogenous bone-derived cells (ABC) with bovine bone mineral (BBM) on bone formation after single-stage sinus grafting in minipigs. Bone biopsies from the iliac crest were harvested 4 weeks prior to sinus grafting and ABC were culture expanded in vitro. The sinuses of five adult minipigs were grafted. In one sinus of each minipig the space between Schneider's membrane (SM) and the sinus wall was grafted with ABC (325,000 cells per sinus, on average) and BBM. In the other sinus, BBM alone was used. The animals were sacrificed after 12 weeks. One block of each grafted area was prepared by saw cutting and the amount of newly formed bone was analysed by micro-computed tomography (mu-CT). The addition of ABC to BBM significantly increased the amount of newly formed bone compared with BBM alone on mu-CT analysis (ABC+BBM: 29.86+/-6.45% vs. BBM: 22.51+/-7.28% (P=0.016)). Bone formation was increased near SM (ABC+BBM: 20.7+/-4.5% vs. BBM: 15.43+/-3.62% (P=0.009)) and in the middle zone of the grafting material (ABC+BBM: 31.63+/-7.74% vs. BBM: 22.5+/-7.91% (P=0.001)), but not near the local host bone (ABC+BBM: 37.23+/-8.23% vs. BBM: 28.42+/-12.54% (P=0.15)). These preliminary findings indicate that supplementation of cell-free grafting material with culture expanded ABC can stimulate bone formation in areas with low bone-forming capacity.

Animals↗

PubMed2004

Effect of platelet-released growth factors and collagen type I on osseous regeneration of mandibular defects. A pilot study in minipigs.

OBJECTIVE: To study the effects of platelet-released growth factors (PRGF) and collagen type I on bone defect healing in minipig mandibles. MATERIAL AND METHODS: In eight adult minipigs defects were trephined in the facial mandibular wall from extra-oral and filled with collagen+PRGF or with collagen alone. Control defects were left untreated. PRGF were defined as the supernatants obtained after centrifugation of washed, thrombin-activated allogenic cells of platelet-rich plasma. The animals were sacrificed at 4 and 8 weeks. For histological analysis, undecalcified ground specimens stained with the Levai-Laczko stain were used. RESULTS: For the entire follow-up, the amount of newly formed bone was 35.49 +/- 3.84% in the collagen+PRGF group, 46.34 +/- 3.84% in the collagen-only group and 33.83 +/- 4.11% in the controls. The differences between the collagen+PRGF and the collagen-only group (p = 0.0343), and between the collagen-only group and the controls (p = 0.0305) were significant. Histologically, defects filled with collagen+PRGF showed inflammatory reactions at 4 weeks, and new bone formation near the remnants of the filler collagen was reduced. CONCLUSION: The data suggest that collagen type I alone, but not its combination with PRGF can support the early stages of cortical bone repair.

Animals↗

PubMedDate not supplied

Enhanced bone-to-implant contact by platelet-released growth factors in mandibular cortical bone: a histomorphometric study in minipigs.

PURPOSE: To determine the effects of platelet-released growth factors (PRGF) on bone-to-implant contact (BIC) in minipig cortical bone. MATERIALS AND METHODS: In each of 8 adult minipigs, 2 implants were placed in the facial wall of the mandible, one implant with and one without PRGF. PRGF was defined as the supernatant from washed, thrombin-activated, allogenic, platelet-rich plasma cells obtained after centrifugation. Four animals were sacrificed at 4 weeks, and the remaining 4 were sacrificed at 8 weeks. For histomorphometric analyses, undecalcified ground specimens were prepared and stained with the Levai-Laczko stain. RESULTS: For the entire follow-up time, 55.30% BIC was found with PRGF versus 38.91% without PRGF (P = .0198). At 4 weeks, BIC was 44.20% with PRGF versus 29.62% without PRGF (P = .0632), and at 8 weeks there was 70.36% BIC with PRGF versus 48.20% without PRGF (P = .1221). DISCUSSION: Growth factors and other molecules released upon activation of platelet-rich plasma cells can enhance implant anchorage in cortical bone. PRGF obtained from allogenic sources does not impair healing. CONCLUSION: The results indicated that a single application of PRGF before implant placement can be sufficient to increase the percent BIC in minipig cortical bone.

Animals↗