Poster
Presentation 24:
Osteoblast Attachment to Titanium Surfaces as a Function
of Surface Charge
Heipp P.S.1, Chapovsky F.2, Brennan
D.J.3, Pourezzaei K.4, Beard R.B.4, Hickok
N.2, DiNardo N.J.1,3, Tuan R.S.2 and Marcolongo
M.1,5
1School of Biomedical Engineering
3Deptartment of Physics
4Deptartment of Electrical and Computer
Engineering
5Deptartment of Materials Engineering
Drexel University
Philadelphia PA 19104
psheipp@drexel.edu
(215) 895-1283
2Dept. of Orthopaedic Surgery Research,
Thomas Jefferson University
Philadelphia PA
Osseointegration of orthopaedic implants is paramount
to the success of the devices for non-cemented hip and knee prostheses.
The ability of the surface to stably interact with the extracellular matrix
is critical for osseointegration. We examined osteoblast attachment to
titanium surfaces in vitro by utilizing an electric field generating device
to change the polarity and magnitude of the surface charge. In this way,
we have been able to uncouple the effects of surface charge from those
of surface chemistry and topography. Titanium surfaces were prepared by
RF sputtering onto 4" diameter silicon wafers, then cleaved into 15 mm
squares. Electric fields of +/-12.7 V/m and +/- 38.1 V/m were applied and
compared to a zero-field control group via parallel plate configuration.
SAOS-2 osteoblastic cells were plated on Ti surfaces in DMEM/F12 containing
10% FCS, and allowed to adhere for 6 hours. Cells were then incubated for
30 min in 10 mM 2',7'-bis(2-carboxyethyl)-5-carboxyfluorescein acetoxymethyl
ester (BCECF-AM), then lysed in 1% Triton X-100. Adhesion was measured
spectrofluorometrically. Our preliminary adhesion assays, osteoblastic
cells showed an increase in cell attachment for negatively-charged surfaces
with respect to a neutral control group. Bone is reported to have a negative
zeta potential. We suggest that negative surface charge induces attachment
of osteoblastic cells, perhaps through facilitated attachment of ECM proteins
necessary for osteoblastic cell adhesion. Further refinements of the experiment
will help us to understand the effect of surface charge on cell adhesion.
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