Objective—To examine age-related efficacy of bone
morphogenetic protein (BMP)-2, ascorbate, and
dexamethasone as osteogenic inducers in canine
marrow-derived stromal cells (MSCs).
Sample Population—Samples of femoral bone marrow
obtained from 15 skeletally immature (< 1 year
old) and 4 skeletally mature (> 1.5 years old) dogs.
Procedure—First-passage canine MSC cultures were
treated with 100 µg of ascorbate phosphate/mL,
10–7M dexamethasone, 100 ng of BMP-2/mL, or a
combination of these osteoinducers. On day 6, cultures
were harvested for quantitation of alkaline phosphatase
(ALP) activity and isolation of RNA to prepare
cDNA for real-time polymerase chain reaction analyses
of osteoblast markers.
Results—Early markers of osteogenesis were
induced in canine MSCs by BMP-2 but not dexamethasone.
In young dogs, the combination of BMP-
2 and ascorbate yielded the highest ALP mRNA concentrations
and activity. This combination also
induced significant increases in mRNA for osteopontin
and runt-domain transcription factor 2. In comparison
to MSCs from immature dogs, those from
mature dogs had diminished ALP activity in response
to BMP and ascorbate. Results for cultures treated
with 3,4-dehydroproline suggested that ascorbateinduced
production of extracellular matrix was important
for maximal BMP-2 response in canine MSCs.
Conclusions and Clinical Relevance—BMP-2 was
capable of inducing markers of osteogenesis in shortterm
cultures of canine MSCs. In MSCs obtained
from skeletally immature dogs, ascorbate was
required for maximal effects of BMP. These results
define optimal conditions for stem cell osteogenesis
in dogs and will facilitate development of stem
cell–based treatments for dogs with fractures. (Am J
Vet Res 2005;66:1729–1737)