Biomedical subjects

Olaf Kilian

Publications and source records attributed to Olaf Kilian.

7 recordsLinked to original sources

PubMed2005

Glycerol-l-lactide coating polymer leads to delay in bone ingrowth in hydroxyapatite implants.

Glycerol-l-lactide as coating polymer for the delivery of basic fibroblast growth factor (bFGF) from hydroxyapatite (HA) ceramic implants was shown to lead to significant delay in bone ingrowth into the implants compared to implants without the coating polymer. The purpose of this work was to study bone ingrowth in HA ceramic implants with and without the coating polymer but without growth factors to enable differentiation between a locking effect of the pores by the polymer and the fact of inactivation of the growth factors by the polymer, which could both be possible for the delay. A defect was created in the subchondral region of both femurs in 24 miniature-pigs and was either filled by the HA implants with or without the coating polymer. Histomorphometry showed a significant delay in bone ingrowth in the polymer coated implants both after 6 and 12 weeks. Detailed histology revealed that the HA pores were completely "locked" by the polymer leading to complete loss of the osteoconductive properties of the HA. Also electron microscopy showed filling of the HA pores by the polymer. Therefore, it can be concluded that glycerol-l-lactide should not be used to coat HA ceramic implants due to significant delay in bone ingrowth.

Animals↗

PubMed2005

The tissue response to an alkylene bis(dilactoyl)-methacrylate bone adhesive.

Gluing is an attractive technique to fix small bone fragments. However, to date no bone adhesive could be established successfully for all day clinical use. The purpose of this experimental study was to investigate the biocompatibility of a new bone glue based on alkylene bis(dilactoyl)-methacrylate in 36 rabbits. Monocondylar osteotomy of the distal femur was performed and bone glue was applied into the osteotomy gap in 24 rabbits. The remaining 12 animals served as controls. In all rabbits the osteotomy was subsequently stabilized by K-wire osteosynthesis. Six animals of the glue group and 3 controls were euthanized after 7, 21, 42, and 84 days, respectively. Fracture healing and degradation pattern of the glue was studied using histological, histomorphometrical, scanning electron microscopical, and radiological methods. Good resorption of the glue by mononuclear and multinucleated giant cells without prolonged inflammatory processes was observed in the glue group. Histomorphometrical analysis did not reveal any significant differences in fracture healing between the glue and control group at any time. Complete remodelling of the former osteotomy gap was found in all rabbits after 84 days. This bioresorbable bone adhesive exhibited good biocompatibility and its degradation did not interfere with physiological fracture healing.

Animals↗

PubMed2005

Plasma transglutaminase factor XIII induces microvessel ingrowth into biodegradable hydroxyapatite implants in rats.

Coagulation factor XIII is a member of the transglutaminase-family. Transgluaminases cross-link either fibrin monomers in blood coagulation or extracellular proteins in extracellular matrix formation. In early stages of bone healing migration and proliferation of endothelial cells lead to formation of new vessels. The aim of this study was to investigate the angiogenetic activity of plasma factor XIII in bone defects filled with nanoparticulate hydroxyapatite paste. A critical size defect was created in the tibial head of rats which was not filled in group I. In group II the defect was filled with hydroxyapatite paste, and in group III with hydroxyapatite paste enriched with factor XIII. Ten days after surgery angiogenesis in the defects was assessed using immunohistochemistry and confocal laser scanning microscopy. Ac16 antibody was used to detect activation of factor XIII into factor XIIIA. In defects without biomaterial (group I) vessel-rich connective tissue and diffuse distribution of capillaries was observed. In defects filled with pure hydroxyapatite (group II) formation of capillaries was limited to the host bone-hydroxyapatite interface. In contrast, addition of plasma factor XIII to hydroxyapatite (group III) stimulated formation of vessels within the biomaterial. The current study reveals that factor XIII can improve angiogenesis in hydroxyapatite.

Absorbable Implants↗

PubMed2005

New blood vessel formation and expression of VEGF receptors after implantation of platelet growth factor-enriched biodegradable nanocrystalline hydroxyapatite.

Vascular endothelial growth factor (VEGF) plays a key role for the interaction of osteoblasts and endothelial cells and, therefore, is an important factor for the osteointegration of bone substitutes. The aim of the current work was to study the effects of platelet growth factors (PLF) on new blood vessel formation and VEGF-receptors expression pattern in bone defects filled with nanocrystalline hydroxyapatite (HA) paste in miniature-pigs. Conventional histology, RT-PCR for VEGF and receptors mRNA, Western blot analysis, immunohistochemical staining and quantitative assessment of newly formed vessels was performed. HA enriched with platelet growth factor (HA/PLF+) led to an up-regulation of VEGF-R1 synthesis, a slightly enhanced number of newly formed vessels with higher sprouting activity compared with HA without PLF (HA/PLF-) filling defects. These observation are most likely attributable to a stimulating effect of TGF-ss from the platelet factor on VEGF expression in osteoblasts.

Animals↗

PubMed2004

Human reaming debris: a source of multipotent stem cells.

The biological characteristics of human reaming debris (HRD) generated in the course of surgical treatment of long bone diaphyseal fractures and nonunions are still a matter of dispute. Therefore, the objective of the present investigation has been to characterize the intrinsic properties of human reaming debris in vitro. Samples of reaming debris harvested from 12 patients with closed diaphyseal fractures were examined ultrastucturally and were cultured under standard conditions. After a lag phase of 4-7 days, cells started to grow out from small bone fragments and established a confluent monolayer within 20-22 days. The cells were characterized according to morphology, proliferation capacity, cell surface antigen profile, and differentiation repertoire. The results reveal that human reaming debris is a source of multipotent stem cells which are able to grow and proliferate in vitro. The cells differentiate along the osteogenic pathway after induction and can be directed toward a neuronal phenotype, as has been shown morphologically and by the expression of neuronal markers after DMSO induction. These findings have prompted interest in the use of reaming debris-derived stem cells in cell and bone replacement therapies.

Adult↗

PubMed2003

Bone ingrowth in bFGF-coated hydroxyapatite ceramic implants.

This experimental study was performed to evaluate angiogenesis, bone formation, and bone ingrowth in response to osteoinductive implants of bovine-derived hydroxyapatite (HA) ceramics either uncoated or coated with basic fibroblast growth factor (bFGF) in miniature pigs. A cylindrical bone defect was created in both femur condyles of 24 miniature pigs using a saline coated trephine. Sixteen of the 48 defects were filled with HA cylinders coated with 50 microg rhbFG, uncoated HA cylinders, and with autogenous transplants, respectively. Fluorochrome labelled histological analysis, histomorphometry, and scanning electron microscopy were performed to study angiogenesis, bone formation and bone ingrowth. Complete bone ingrowth into bFGF-coated HA implants and autografts was seen after 34 days compared to 80 days in the uncoated HA group. Active ring-shaped areas of fluorochrome labelled bone deposition with dynamic bone remodelling were found in all cylinders. New vessels could be found in all cylinders. Histomorphometric analysis showed no difference in bone ingrowth over time between autogenous transplants and bFGF-coated HA implants. The current experimental study revealed comparable results of bFGF-coated HA implants and autogenous grafts regarding angiogenesis, bone synthesis and bone ingrowth.

Animals↗

PubMed2002

Reconstruction of the lower leg with the sural artery flap.

BACKGROUND: Soft tissue covering on the lower leg is frequently a difficult challenge and causes increasing problems for treatment in smaller hospitals. We introduce a plastic surgery method for covering these soft tissue defects. METHOD: An island of skin, centered above the sural nerve, is cut out in the middle dorsal area of the lower leg. The subcutaneous vascular pedicle is prepared along the nerve. The gained skin flap is rotated into the defect site and fixed without tension. The wound of the donor-site defect is usually closed primarily, and the flap pedicle is covered with Meshcraft. RESULTS: In 18 of the 21 patients treated by this method the flap healed without functional impairment, one patient experienced a necrosis leading to the loss of the flap. And a partial loss of the skin island was recorded in two cases, complete healing was achieved by means of Meshcraft transplantation. CONCLUSIONS: The superficial sural artery flap usually results in a reliable and complete healing of soft tissue defects within the area of the lower legs with justifiable operational expenditures also for elderly patients and those with vascular ailments.

Adult↗