Download amounts of bmp-2, bmp-4, bmp-7 and tgf

AMOUNTS OF BMP-2, BMP-4, BMP-7 AND TGF-Β1 CONTAINED IN DBM PARTICLES AND DBM EXTRACT
+*Kay, JF; *Khaliq, SK; *King, E; **Murray, SS; **Brochmann, EJ
+*IsoTis OrthoBiologics, Irvine CA
**VA Greater Los Angeles Healthcare System, Sepulveda CA
[email protected]
INTRODUCTION
Figure 2: Quantification of BMP-4
(n =12, error bars represent the standard deviation from the mean)
1.20
* p = .001
0.80
0.60
0.40
*
0.20
0.00
IsoTis DBM
IsoTis Accell
Figure 3: Quantification of BMP-7
(n =12, error bars represent the standard deviation from the mean)
160.00
* p < .001
*
140.00
120.00
100.00
ng/g
MATERIALS AND METHODS
BMP-2, BMP-4, BMP-7 and TGF-β1 levels were detected and
quantified for twelve lots of IsoTis DBM and corresponding twelve lots
of DBM extract (extract was produced from the same twelve DBM lots)
using commercially available enzyme-linked immunoassays (ELISA)
kits (Quantikine Immunoassay Kits, R&D Systems, Minneapolis, MN).
Test materials were e-beam sterilized and assayed per instructions
included in each kit. Methods for extraction of BMPs and growth
factors prior to assay were those outlined in published studies. 2,3
*
1.00
ng/g
Bone morphogenetic proteins (BMPs) have been identified as the
osteoinductive element present in demineralized bone matrix (DBM);1 as
a result, the focus on identifying and quantifying selected factors in
DBM has increased in recent years. Other complementary growth
factors that play a role in the bone forming process have also been
detected in DBM. These include basic fibroblast growth factor (FGF-2),
insulin-like growth factors 1 and 2 (IGF-1 and IGF-2), platelet derived
growth factor, and transforming growth factor-β1 (TGF-β1). Due to the
differences in bone forming characteristics between individual donors
and tissue banks, confirmation and measurement of osteoinductivity
plays a vital role in predicting the clinical success of the bone graft
produced from a DBM lot.2 The traditional method for determining
osteoinductivity has been using an ectopic bone formation model in
athymic (nude) rodents. This model is qualitative and is thus limited in
its ability to detect and quantify osteoinductive BMPs and
complementary growth factors. This study investigated the content of
BMP-2, BMP-4, BMP-7 and TGF-β1 in twelve lots of IsoTis’ DBM
(IsoTis DBM) and the corresponding twelve lots of DBM extract (IsoTis
Accell).
*
80.00
60.00
40.00
20.00
RESULTS
BMP-2, BMP-4, BMP-7 and TGF-β1were detected in all twelve lots
of DBM and corresponding twelve lots of DBM extract. Mean results,
expressed as nanograms per gram (ng/g), are plotted in Figures 1 - 4.
Statistical comparison using a Student’s t-test revealed that DBM extract
contained significantly more BMP-2, BMP-4, BMP-7 and TGF-β1 than
DBM particles alone (p < 0.001 for BMP-2, BMP-7, TGF-β1; p = 0.001
for BMP-4).
0.00
IsoTis DBM
IsoTis Accell
Figure 4: Quantification of TGF-β1
(n =12, error bars represent the standard deviation from the mean)
350.00
* p < .001
*
300.00
250.00
Figure 1: Quantification of BMP-2
(n =12, error bars represent the standard deviation from the mean)
200.00
ng/g
50.00
*
45.00
150.00
* p < .001
40.00
100.00
*
35.00
50.00
ng/g
30.00
25.00
0.00
IsoTis DBM
20.00
IsoTis Accell
15.00
10.00
*
5.00
0.00
IsoTis DBM
IsoTis Accell
1
Urist MR et al. Bone cell differentiation and growth factors. Science.
1983; 220:680-686.
2
Blum B et al. Measurement of BMPs and other growth factors in
DBM. Orthopedics. 2004; 27:161-165
3
Yu RR et al. Quantitative Assay for BMP-2/4 and TGF-β1 extracted
from human bone. 2001 Soc. for Biomat’ls. 27th Ann. Mtg transactions.
DISCUSSION
Quantified levels of BMP-2, BMP-4, BMP-7 and TGF-β1 were
significantly different between DBM (IsoTis DBM) and DBM extract
(IsoTis Accell). In all four analyses, DBM extract contained
significantly more BMP-2, BMP-4, BMP-7 and TGF-β1than DBM
particles alone. Standard deviation for most groups was relatively high,
and this may be attributed to differing osteoinductivity between donor
lots as well as group sample size.
52nd Annual Meeting of the Orthopaedic Research Society
Paper No: 1724