Biomedical subjects

Christoph Sprecher

Publications and source records attributed to Christoph Sprecher.

4 recordsLinked to original sources

PubMed2005

Wear particles and surface topographies are modulators of osteoclastogenesis in vitro.

Prosthetic and osteosynthetic implants from metal alloys will be indispensable in orthopedic surgery, as long as tissue engineering and biodegradable bone substitutes do not lead to products that will be applied in clinical routine for the repair of bone, cartilage, and joint defects. Therefore, the elucidation of the interactions between the periprosthetic tissues and the implant remains of clinical relevance and several factors are known to affect the longevity of implants. Within this study, the effects of metal particles and surface topography on the recruitment of osteoclasts was investigated in vitro in a coculture of osteoblasts and bone marrow cells. The cells were grown in the presence of particles of different sizes and chemical composition or on metal discs with polished or sandblasted surfaces, respectively. At the end of the culture, newly formed osteoclasts were counted. Osteoclastogenesis was reduced when particles were added directly to the coculture. The effect depended on the size of the particles, small particles exerting stronger effects than larger ones. The chemical composition of the particles, however, did not affect the development of osteoclasts. In cocultures grown on sandblasted surfaces, osteoclasts developed at higher rates than they did in cultures on polished surfaces. The data demonstrate that wear particles and implant surfaces affect osteoclastogenesis and thus may be involved in the induction of local bone resorption and the formation of osteolytic lesions, leading eventually to the loosening of orthopedic implants.

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PubMed2005

The decrease of particle-induced osteolysis after a single dose of bisphosphonate.

The most common cause of implant failure in joint replacement is aseptic loosening due to particle-induced osteolysis. Bisphosphonates have been shown to be effective against particle-induced osteolysis when administered daily. We investigated the effect of a single subcutaneous dose of a more potent third generation bisphosphonate on particle-induced osteolysis. We utilized the murine calvaria osteolysis model in C57BL/J6 mice. Bone resorption was measured as resorption within the midline suture using Giemsa staining. Twenty-eight mice were used, seven per group. Seven animals were treated with a single dose of zoledronic acid (ZA) directly after surgery and seven animals were treated four days postoperatively. For statistical analysis one-way ANOVA and a Student's t-test were used. Bone resorption was 0.26+/-0.09 mm(2) in animals with particle implantation, 0.14+/-0.05 mm(2) in animals with particle implantation and ZA treatment directly after surgery (p = 0.0047), and 0.15+/-0.05 mm(2) in animals with particle implantation and ZA treatment on the fourth postoperative day (p = 0.006). In conclusion, particle-induced bone resorption was markedly decreased by a single s.c. dose of a third generation bisphosphonate. This important new finding holds great promise, because single dose treatment of particle-induced osteolysis may reduce side effects compared to repeated application of bisphosphonates.

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PubMed2005

Stimulation of bone formation by zoledronic acid in particle-induced osteolysis.

We investigated the effect of a single subcutaneous dose of zoledronic acid on particle-induced osteolysis and observed excessive regional new bone formation. We utilized the murine calvarial osteolysis model and polyethylene particles in C57BL/J6 mice. Twenty-eight mice were used, seven per group. Specimens were stained with Giemsa dye. The osteoid tissue area was determined. Bone thickness was measured as an indicator of bone growth. Net bone growth was significantly increased in animals with zoledronic acid treatment: 0.02 mm(2)+/-0.03 mm(2) in animals with particle implantation only (group 2), 0.25 mm(2)+/-0.08 mm(2) with particle implantation and zoledronic acid treatment directly after surgery (group 3; p=0.0018), and 0.21 mm(2)+/-0.11 mm(2) with particle implantation and zoledronic acid treatment on the fourth postoperative day (group 4; p=0.0042). The mean bone thickness was 0.2 mm+/-0.04 mm (range 0.17 mm-0.31 mm) in group 1 (sham controls) and 0.16 mm+/-0.02 mm (range 0.14 mm-0.19 mm) in group 2, 0.31 mm+/-0.04 mm (range 0.28 mm-0.39 mm) in group 3, and 0.29 mm+/-0.02 mm (range 0.28 mm-0.34 mm) in group 4. Student's t-test revealed a statistically significant difference between groups 2 and 3 (p=0.00042), and groups 2 and 4 (p=0.0019). In conclusion, our observational study suggests that zoledronic acid may stimulate bone apposition locally in the process of particle-induced osteolysis.

Animals↗

PubMed2004

The effectiveness of polyethylene versus titanium particles in inducing osteolysis in vivo.

Bearing surface wear and periprosthetic osteolysis due to wear particles are among the most common reasons for joint replacement failure. A murine calvarial model of wear particle-induced osteolysis has been used to identify different biologic factors associated with this problem and to test nonsurgical methods of modulating the host response to particulate debris. This model has utilized titanium particles, however, in clinical practice the most common source of particulate debris is polyethylene particles from bearing surface wear. We now report a calvarial model of wear particle-induced osteolysis based on commercially available polyethylene particles. We found that compared to sham surgery osteoclast recruitment and bone resorption can be induced by introduction of the titanium particles or polyethylene particles. However, bone resorption was significantly higher with polyethylene particles compared to titanium particles (p=0.02). We consider the polyethylene based murine calvarial model of wear particle-induced osteolysis a reliable and clinically relevant tool to understand the host factors and potential pharmacologic interventions that can influence wear debris generated osteolysis. This model might serve as an extension of the well-established titanium based bone resorption model.

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