[Comparative in vitro analysis of vacuum plasma-sprayed titanium implants--evaluation of OPG, Osteokalzin and AP expression].
BACKGROUND
The purpose of this study was to evaluate the influence of different surface topographies on the expression of bone cell-associated proteins, such as osteoprotegerin (OPG), osteocalcin and alkaline phosphatase (AP), and the production of the extracellular matrix (ECM) in vitro. Another aspect was the question as to whether a hydroxyapatite (HA) coating offers additional advantages. Vacuum plasma-sprayed (VPS) pure titanium was used to generate different surface topographies.


METHODS
The in vitro response of human bone marrow cells to VPS implants (porosity ranging from 25 to 50%, pore size ranging from 50 to 200 microm and roughness ranging from 0.191 to 0.547 mm) and cancellous structured titanium (cs-Ti) as a reference material (55% porosity, pore size of 500 microm, roughness 0.836 mm) were compared. The expression of bone cell-associated proteins, such as OPG, osteocalcin and alkaline phosphatase (AP), was evaluated. Scanning electron microscopy (SEM) was used to judge the production of ECM.


RESULTS
All implant materials induced the release of OPG, osteocalcin and AP. Significant differences were evident between the cs-Ti and the different VPS-Ti surface structures. There was no difference in the response between the VPS-Ti surfaces. SEM showed a dense and increased production of ECM on the VPS-Ti surfaces. An additional HA coating caused a faster production of ECM and higher levels of OPG.


CONCLUSIONS
The in vitro data presented here demonstrate the superiority of VPS-Ti surfaces over cs-Ti, which is already in clinical use. Differences between the VPS-Ti surfaces were not evident. Presumably, VPS-Ti surfaces offer good prerequisites for a successful integration of the implant in the surrounding tissue. An additional HA coating could influence these events positively.
Endres
S
S
Klinik für Orthopädie und Rheumatologie, Elisabeth-Klinik GmbH Bigge/Olsberg, Olsberg, Germany. endres_s@freenet.de
Wilke
M
M
Knöll
P
P
Frank
H
H
Kratz
M
M
Windler
M
M
Wilke
A
A
D000469:Alkaline Phosphatase / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology; D020099:Coated Materials, Biocompatible; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology; D015675:Osteocalcin / Q000378:metabolism*; D053244:Osteoprotegerin / Q000378:metabolism*; D010949:Plasma; D016062:Porosity; D011474:Prosthesis Design; D013499:Surface Properties; D014025:Titanium; D014618:Vacuum
D020099:Coated Materials, Biocompatible; D053244:Osteoprotegerin; D015675:Osteocalcin; D014025:Titanium; D000469:Alkaline Phosphatase