Related Experiment Videos
Polymethylmethacrylate particles enhance DNA and protein synthesis of human fibroblasts in vitro
C G Frondoza1, K T Tanner, L C Jones
1Department of Orthopaedic Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Abstract:
Aseptic loosening of polymethylmethacrylate (PMMA) fixed prosthesis is characterized by formation of a radiolucent fibrous membrane, accumulation of inflammatory cells and osteolysis. Since this membrane is produced by fibroblasts, it is likely that these connective tissue cells play a critical role in the loosening process. Whether fibroblasts form the radiolucent membrane in response to stimulation by PMMA has not yet been established, nor is it known whether fibroblasts play a role in attracting inflammatory cells to the bone-cement interface by secreting chemical mediators. To address this question, we analyzed the in vitro response of normal human fibroblasts to PMMA. Cells were plated with 10(5)/mL Dulbecco minimal essential medium and were incubated 4 h later with PMMA particles, polystyrene (PS) particles, or medium alone. Proliferative capacity monitored by incorporation of 3H-thymidine was significantly increased following a 48 h exposure to PMMA. Protein synthesis determined by incorporation of 14C-leucine and 14C-proline was also increased. In contrast, levels of secreted prostaglandin (PG) E2 assayed immunoenzymatically was not altered by PMMA. Fibroblasts exposed to control PS did not change their proliferative or protein synthetic activity. Fibroblasts internalized PMMA and PS particles without detectable ultrastructural damage. PMMA enhancement of fibroblast proliferative capacity and protein synthetic ability observed in our in vitro assay system suggests similar effects on fibroblasts in vivo.
Insights
Polymethylmethacrylate (PMMA) particles stimulate fibroblasts, increasing their proliferation and protein synthesis. This suggests fibroblasts play a key role in prosthesis loosening by forming membranes and attracting inflammatory cells.
Area of Science:
- Biomaterials Science
- Cell Biology
- Orthopedic Research
Background:
- Aseptic loosening of polymethylmethacrylate (PMMA) fixed prostheses involves a fibrous membrane, inflammatory cells, and osteolysis.
- Fibroblasts produce this membrane, suggesting a critical role in prosthesis loosening.
Purpose of the Study:
- To investigate the in vitro response of human fibroblasts to PMMA particles.
- To determine if PMMA stimulates fibroblast proliferation and protein synthesis.
- To assess PMMA's effect on fibroblast-secreted prostaglandin E2 and inflammatory cell attraction.
Main Methods:
- Human fibroblasts were exposed to PMMA particles, polystyrene particles (control), or medium alone in vitro.
- Proliferative capacity was measured using 3H-thymidine incorporation.
- Protein synthesis was assessed via 14C-leucine and 14C-proline incorporation.
- Prostaglandin E2 levels were measured using immunoenzymatic assay.
Main Results:
- PMMA significantly increased fibroblast proliferation and protein synthesis after 48 hours.
- Polystyrene particles did not alter fibroblast activity.
- PMMA exposure did not alter prostaglandin E2 secretion.
- Fibroblasts internalized PMMA and polystyrene particles without apparent damage.
Conclusions:
- PMMA enhances fibroblast proliferative and protein synthetic capacities in vitro.
- These findings suggest PMMA influences fibroblast behavior in vivo, potentially contributing to the fibrous membrane formation and prosthesis loosening.
- Further research is needed to confirm the role of fibroblasts in attracting inflammatory cells via chemical mediators.