Biomedical subjects

Christoph H Lohmann

Publications and source records attributed to Christoph H Lohmann.

8 recordsLinked to original sources

PubMed2007

Platelet-rich plasma inhibits demineralized bone matrix-induced bone formation in nude mice.

BACKGROUND: It is unclear whether platelet-rich plasma is a clinically effective adjunct to osteoinductive agents such as demineralized bone matrix. It contains platelet-derived growth factor (PDGF), which decreases osteoinduction by human demineralized bone matrix in nude-mouse muscle, suggesting that platelet-rich plasma may also have a negative impact. This study tested the hypothesis that platelet-rich plasma reduces demineralized bone matrix-induced bone formation and that this effect varies with donor-dependent differences in platelet-rich plasma and demineralized bone matrix. METHODS: Human platelet-rich plasma was prepared from blood from six men (average age [and standard error of the mean], 29.2 +/- 2.4 years). Platelet numbers were determined, and growth factors were quantified before and after platelet activation. Human demineralized bone matrix from two donors (demineralized bone matrix-1 and demineralized bone matrix-2) was mixed with activated platelet-rich plasma and was implanted bilaterally in the gastrocnemius muscle in eighty male nude mice (eight implants per variable). Fifty-six days after implantation, the hindlimb calf muscles were harvested for histological analysis. Osteoinduction was evaluated with use of a qualitative score and morphometric measurements of ossicle size, new bone formation, and residual demineralized bone matrix. RESULTS: Compared with platelet-poor plasma, platelet-rich plasma preparations exhibited a fourfold increase in the platelet count, a fifteenfold increase in the amount of transforming growth factor-beta, a sixfold increase in the amount of PDGF-BB, a fivefold increase in the amount of PDGF-AA, and a twofold increase in the amount of PDGF-AB. Demineralized bone matrix-1 was more osteoinductive than demineralized bone matrix-2, as determined on the basis of a greater ossicle area. The effect of platelet-rich plasma was either neutral or inhibitory depending on the demineralized bone matrix batch. When used with demineralized bone matrix-1, platelet-rich plasma did not alter the qualitative score or overall ossicle size, but it decreased the new bone area. When used with demineralized bone matrix-2, platelet-rich plasma reduced the qualitative score, ossicle area, and new bone area and increased the amount of residual demineralized bone matrix. The effects on osteoinduction also varied with the donor of the platelet-rich plasma. CONCLUSIONS: Platelet-rich plasma decreased the osteoinductivity of demineralized bone matrix implanted in immunocom-promised mice, and the activities of both demineralized bone matrix and platelet-rich plasma were donor-dependent.

Adult↗

PubMed2005

Giant synovial osteochondromatosis of the acromio-clavicular joint in a child. A case report and review of the literature.

Primary intra-articular synovial chondromatosis represents an uncommon condition involving mainly the large joints predominantly of middle-aged adults. We herein document the first case of synovial chondromatosis affecting the acromio-clavicular joint of a 10-year-old girl, characterized by a solitary huge intra-articular osteochondromatous body (giant synovial chondromatosis) that had caused dislocation and deformation of the lateral portion of the clavicle. Successful surgical treatment consisted of removal of the osteochondral body and replacement of the clavicle by fixation with a K-wire.

Acromioclavicular Joint↗

PubMed2005

Metal-on-metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study.

BACKGROUND: Some patients who have a total hip replacement with a second-generation metal-on-metal articulation have persistent or early recurrence of preoperative symptoms. Characteristic histological changes in the periprosthetic tissues suggested the development of an immunological response. Therefore, in order to determine the relevance of these symptoms, we performed a study of the clinical data and periprosthetic tissues associated with endoprostheses with a metal-on metal articulation that had been retrieved at revision. METHODS: Periprosthetic tissues as well as the clinical data on the patients were obtained from the first nineteen consecutive revisions performed at the treating hospitals. At the time of the revision, fourteen patients had the metal-on-metal articulation exchanged for either an alumina-ceramic or a metal-on-polyethylene articulation. Five patients received another second-generation metal-on-metal total joint replacement. Five-micrometer sections were prepared from the tissue samples, were stained with routine and immunohistochemical methods, and were examined histologically. Histological specimens from three groups of patients, two of which were treated with non-metal-on-metal implants, served as controls. RESULTS: The majority of patients had persistence of their preoperative pain or early recurrence of the pain after the original total hip replacement, and often a pronounced hip joint effusion had developed after the original replacement. Radiographic follow-up showed the development of radiolucent lines in five hips and of osteolysis in another seven hips. At the revision surgery, both the cup and the stem were found to be well fixed in nine patients. The characteristic histological features were diffuse and perivascular infiltrates of T and B lymphocytes and plasma cells, high endothelial venules, massive fibrin exudation, accumulation of macrophages with droplike inclusions, and infiltrates of eosinophilic granulocytes and necrosis. Only a few metal particles were detected. Immunohistochemical analysis demonstrated that the cellular reaction was still active. The patients who received another second-generation metal-on-metal articulation at the time of the revision had no decrease in symptoms. In the control group of tissues obtained at revisions of endoprostheses without cobalt, chromium, or nickel articulations, there were no similar signs of immune reactions. CONCLUSIONS: These histological findings support the possibility of a lymphocyte-dominated immunological response. Although the prevalence of this reaction is low, the persistence or early reappearance of symptoms, including a marked joint effusion and the development of osteolysis, after primary implantation may suggest the possibility of such a reaction.

Aluminum Oxide↗

PubMed2005

Platelet-derived growth factor inhibits demineralized bone matrix-induced intramuscular cartilage and bone formation. A study of immunocompromised mice.

BACKGROUND: Platelet-derived growth factor (PDGF) has been proposed as a therapeutic agent to promote bone-healing. The purpose of this study was to examine the effect of PDGF on the ability of human demineralized bone matrix to induce bone formation in a nude-mouse muscle-implantation model. We also examined whether platelet-rich plasma, which contains PDGF, also modulates osteoinduction in this model. METHODS: Human demineralized bone matrix, previously shown to be osteoinductive in the calf muscles of nude mice, was mixed with PDGF-BB (0, 0.1, 1, and 10 microg/10 mg of demineralized bone matrix) and was implanted bilaterally in the calf muscles of immunocompromised (nu/nu) mice (six mice in each group). Heat-inactivated demineralized bone matrix was used as a control. Tissue was harvested at fourteen, twenty-eight, and fifty-six days after implantation. Platelet-rich plasma was prepared from the blood of a healthy donor with use of the Harvest PRP preparation device, activated with thrombin, and mixed with active and inactive demineralized bone matrix. Fifty-six days post-implantation, tissues were harvested. Osteoinduction was assessed with use of a qualitative scoring system and with quantitative histomorphometry. RESULTS: Cartilage was present at fourteen days in all tissues that had received an implant, but the amount decreased as the PDGF concentration increased. PDGF reduced bone formation at twenty-eight days in a dose-dependent manner. This inhibitory effect was resolved by fifty-six days, except in tissues in which demineralized bone matrix and 10 microg of PDGF had been implanted. In sites treated with 10 microg of PDGF, the area of new bone was decreased and the area of bone marrow was reduced at twenty-eight and fifty-six days. PDGF also appeared to retard resorption of demineralized bone matrix in a dose-dependent manner. Platelet-rich plasma reduced osteoinduction by human demineralized bone matrix that had high osteoinductive activity and had no effect on osteoinduction by demineralized bone matrix with low activity. CONCLUSIONS: PDGF inhibits, in a dose-dependent manner, intramuscular osteoinduction and chondrogenesis by demineralized bone matrix in immunocompromised mice. Platelet-rich plasma also reduces the osteoinductivity of active demineralized bone matrix.

Analysis of Variance↗

PubMed2004

Growth behavior, matrix production, and gene expression of human osteoblasts in defined cylindrical titanium channels.

The purpose of the current study was to investigate the effect of different diameters of cylindrical titanium channels on human osteoblasts. Titanium samples having continuous drill channels with diameters of 300, 400, 500, 600, and 1000 microm were put into osteoblast cell cultures that were isolated from 12 adult human trauma patients. Cell migration into the drill channels was investigated by transmitted-light microscopy. The DNA content in the drill channels was measured photometrically, collagen type I production was analyzed by enzyme-linked immunosorbent assay (ELISA) and osteocalcin gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR). Formation of mineralized tissue was assessed by microradiographs of histological sections. Within 20 days, cells grew an average of 838 microm (+/-128 microm) into the drill channels with a diameter of 600 microm and were significantly faster (p < 0.05) than in all other channels. Cells produced significantly more osteocalcin messenger RNA (mRNA) in 600-microm channels (p < 0.05) than they did in 1000-microm channels and demonstrated the highest osteogenic differentiation. The channel diameter did not influence collagen type I production. The highest cell density was found in 300-microm channels (p < 0.05). The DNA content of the channels linearly decreased with increasing channel diameters. After 40 days of culture, the proportion of mineralized tissue at the mouth section amounted to 6% in 300-microm channels and to 9-11% in 400-600-microm channels. In 1000-microm channels, only traces of mineralization were detected. Our data suggest that the diameter of cylindrical titanium channels has a significant effect on migration, gene expression, and mineralization of human osteoblasts.

Biocompatible Materials↗

PubMed2004

Expression of the CD44 variant isoform 5 in the human osteoarthritic knee joint: correlation with radiological, histomorphological, and biochemical parameters.

PURPOSE: The purpose of this study was to correlate expression of CD44v5 in osteoarthritic synovium, cartilage, and synovial fluid with radiographical, histomorphological, and biochemical data. METHODS: Cartilage and synovia specimens of 27 patients with osteoarthritis were histomorphologically assessed according to Mankin and Pelletier, respectively. Extended weight-bearing antero-posterior radiographs were evaluated according to Kellgren and Ahlback. Expression of membrane-bound CD44v5 was analyzed by immunohistochemistry and levels of soluble CD44v5 were determined by ELISA. RESULTS: Expression of CD44v5 in cartilage and synovia was detected in 67% and 59% of the patients, respectively. Immunohistochemical findings in cartilage correlated significantly with structural cartilage changes (p < 0.001), whereas no correlation was found between expression in synovia and inflammatory synovial changes. Additionally, no relationship was evident between CD44v5 expression and radiographical data, but expression in cartilage and synovium was significantly correlated with each other (p < 0.04). Surprisingly, expression of CD44v5 in both cartilage and synovia was negatively correlated with synovial fluid levels of TNFalpha (p < 0.03 and p < 0.02, respectively), and no association was evident with levels of IL-1beta. CONCLUSIONS: The data demonstrate expression of CD44v5 in osteoarthritic cartilage and synovia, probably independent of joint inflammation. But more importantly, expression of this receptor variant in cartilage seems to be strongly related to the degree of cartilage destruction.

Adult↗

PubMed2002

Ceramic and PMMA particles differentially affect osteoblast phenotype.

There is increasing evidence that wear debris particles present in periprosthetic tissues have direct effects on osteoblasts. The nature of the cell response varies with the chemistry of the particle and the number of particles. Most studies have used Ti, Ti-6Al-4V, and ultrahigh molecular weight polyethylene (UHMWPE) particles since these materials are most frequently used in implants and as a result, these particles predominate in peri-prosthetic tissues. Ceramics have also been used successfully as load-bearing surfaces in implants for years, although it is unknown how wear debris from these surfaces may contribute to aseptic bone loss. Further, particles resulting from polymethylmethacrylate (PMMA) cements used for fixation may also be involved in aseptic loosening of implants, but how these particles may affect bone formation is unknown. In the present study, we examined whether aluminum oxide (Al2O3), zirconium oxide (ZrO2), and PMMA particles exert effects on osteoblast proliferation, phenotypic expression, and local factor production, and if so, whether the effects were specific to the particle type. ZrO2 particles were produced in a custom-made axial mixer in which ZrO2 containers were filled with ZrO2 bars and 95% ethanol and then rotated continuously at room temperature. PMMA particles were prepared in a ZrO2 roller mill. Al2O3 was produced and provided by Aesculap AG. Particles were endotoxin-free with equivalent circle diameters <3 microm; Al2O3 particles were significantly smaller than ZrO2 or PMMA particles. Particle suspensions were added to confluent cultures of MG63 osteoblast-like cells after diluting them 1:100, 1:10, and 1:1 with culture medium. Cells were incubated with the particles for 24 h. Transmission electron microscopy showed that MG63 cells phagocytosed Al2O3 particles and exhibited ultrastructural changes consistent with cytotoxicity. This was supported by biochemical changes as well. Proliferation, alkaline phosphatase activity, and TGF-beta1 levels were decreased. ZrO2 and PMMA particles increased proliferation and alkaline phosphatase specific activity. The effect of ZrO2 on alkaline phosphatase was targeted to matrix vesicles, the effect of PMMA was greater on the cells. All particles increased prostaglandin E2 production. These results show that Al2O3, ZrO2, and PMMA particles elicit direct effects on osteoblasts and that cell response depends on the particle type. None of the particles tested had the same effect as noted previously for UHMWPE: increased proliferation and decreased alkaline phosphatase. These results may indicate that the response of peri-prosthetic tissues to wear particles may be modulated by the relative contributions of the various particle types present.

Alkaline Phosphatase↗

PubMed2002

Nitric oxide and prostaglandin E2 production in response to ultra-high molecular weight polyethylene particles depends on osteoblast maturation state.

BACKGROUND: Recent studies have shown that osteoblast-like cells respond directly to ultra-high molecular weight polyethylene particles in culture, suggesting that they may be involved in aseptic loosening of endoprostheses. We tested the hypothesis that the state of cell maturation plays a role in the response of osteogenic cells to ultra-high molecular weight polyethylene particles. METHODS: MG63 cells (immature osteoblast-like cells), OCT-1 cells (mature secretory osteoblast-like cells), and MLO-Y4 cells (osteocyte-like cells) were treated for twenty-four hours with commercial ultra-high molecular weight polyethylene particles with an average diameter of 1 mm. The effect of particle treatment on cell proliferation was assessed by measuring the number of cells, whereas the effects on differentiation and local factor production were assessed by measuring the production of osteocalcin, prostaglandin E2, and nitric oxide. The effect of particles on apoptosis was also evaluated. RESULTS: The addition of ultra-high molecular weight polyethylene particles increased the number of MG63 cells, did not affect the number of OCT-1 cells, and led to a decrease in the number of MLO-Y4 cells. The observed changes in cell number were not due to programmed cell death, as no more than 3% of the cells in cultures treated with the highest concentration of particles were undergoing apoptosis. Osteocalcin production was not affected by the addition of particles. Prostaglandin E2 production was increased in all three types of cultures, but the effect was greatest in OCT-1 cell cultures, as was the absolute amount of prostaglandin E2 produced. Nitric oxide production was unaffected in MG63 cell cultures, but it was stimulated in OCT-1 and MLO-Y4 cell cultures. CONCLUSIONS: The results of the present study support the hypothesis that osteoblast cell maturation state plays an important role in the response to ultra-high molecular weight polyethylene particles and that the terminally differentiated osteocyte may be involved in the bone response to wear debris in vivo.

Alprostadil↗