Cobalt, titanium and PMMA bone cement debris influence on mouse osteoblast cell elasticity, spring constant and calcium production activity

Abstract

Periprosthetic osteolysis and implant loosening are the outcomes of wear debris generation in total joint replacements. Wear debris formed from the implanted materials consisting of metals, polymers, ceramic and bone cement initiate the immune system response. Often osteoblasts, the principal cell type in bone tissue adjacent to the prostheses, are directly impacted. In this study, the influence of cobalt, titanium and PMMA bone cement particles of different sizes, charges and compositions on mouse osteoblast adhesion, nanomechanics (elasticity and spring constant) and metabolic activity were investigated. These studies were accompanied by osteoblast mineralisation experiments and cell uptake after exposure to particles at defined time points. Our results demonstrate that alteration of the nanomechanical properties are mainly dependent on the metal type rather than nanoparticles size and concentration. Moreover, despite uptake increasing over exposure time, the cell characteristics exhibit changes predominately after the first 24 hours, highlighting that the cell responses to nanoparticle exposure are not cumulative. Understanding these processes is critical to expanding our knowledge of implant loosening and elucidating the nature of prosthetic joint failure.

Fig. 1. Examples of SEM image of PMMA wear debris. Bar correspond to 1 microns.

Fig. 2. MTT results of MC3T3-E1 cells exposed to cobalt nanoparticles for (a) 24 h, (b) 48 h and (c) 72 h. Control, Co 30 nm and Co 50 nm. *Represent samples statistically different from samples not exposed to particles.

Fig. 3. MTT results of MC3T3-E1 cells exposed to titanium nanoparticles for (a) 24 h, (b) 48 h and (c) 72 h. Control, Ti 30 nm, Ti 25 nm and Ti 100 nm. *Represent samples statistically different from samples not exposed to particles.

Fig. 4. MTT results of MC3T3-E1 cells exposed to PMMA particles for () 24 h, () 48 h and () 72 h. *Represent samples statistically different from samples not exposed to particles.

Fig. 5. Osteoblast mineralisation ability after exposure to particles. Control, Ti 30 nm, Ti 25 nm, Ti 100 nm, Co 25 nm, Co 50 nm and PMMA. *Represent samples statistically different from samples not exposed to particles.

Fig. 6. Mean cell elasticity and spring constant of MC3T3-E1 cells exposed to titanium nanoparticles for (a and d) 24 h, (b and e) 48 h and (c and f) 72 h. Control, Ti 30 nm, Ti 25 nm and Ti 100 nm. *Represent samples statistically different from samples not exposed to particles.

Fig. 7. Mean cell elasticity and spring constant of MC3T3-E1 cells exposed to cobalt nanoparticles for (a and d) 24 h, (b and e) 48 h and (c and f) 72 h. Control, Co 30 nm and Co 50 nm. *Represent samples statistically different from samples not exposed to particles.

Fig. 8. Mean cell elasticity (a), spring constant (b) of MC3T3-E1 cells exposed to PMMA particles for ( ) 24 h, ( ) 48 h and ( ) 72 h.

Fig. 9. Metal uptake of MC3T3-E1 cells exposed to nanoparticles at different concentrations for 24 h, 48 h and 72 h. (a) Ti 25 nm, (b) Ti 30 nm, (c) Ti 100 nm, (d) Co 30 nm, (e) Co 50 nm and (f) PMMA.

Fig. 10. Box and whiskers plot of adhesion force distribution of MC3T3-E1 cells exposed to titanium nanoparticles for (a) 24 h, (b) 48 h and (c) 72 h. Control, Ti 25 nm, Ti 30 nm and Ti 100 nm.

Fig. 11. Box and whiskers plot of adhesion force distribution of MC3T3-E1 cells exposed to cobalt nanoparticles for (a) 24 h, (b) 48 h and (c) 72 h. Control, Co 30 nm and Co 50 nm.

Fig. 12. Box and whiskers plot of adhesion force distribution of MC3T3-E1 cells exposed to PMMA nanoparticles for ( ) 24 h, ( ) 48 h and ( ) 72 h.