Bone Abstracts

Effects of whole bone scaling on isolated osteoblast behaviours are unknown. Exhibiting a huge range in size, inbred canines are an ideal species to determine such relationships. We have therefore undertaken initial studies in both male and female red foxes (Vulpes vulpes), the most abundant and accessible wild canid member in the United Kingdom.

Femoral heads were removed from five fresh red fox cadavers (see details on table) and bone fragments washed in PBS+AB/AM, trypsin-digested and incubated in 0.2% collagenase. Cells from resultant supernatant were seeded in DMEM+10% FCS+AB/AM at 37  °C, 5% CO₂, grown until confluence and then seeded (n=6) at a density of 1.3×10⁴ cells/cm². We determined cell proliferation after 4 days with crystal violet staining and basal alkaline phosphatase (TNAP) activity 24 h post-confluence.

Median cell number reached 35395 [25220–40106] cells/cm² with doubling time of 2.7 [1.9–3.0] days. The male sample had greater cell number 85184 [71789–88947] cells/cm² and shorter doubling time 1.9 [1.8–2.1] days when compared with female samples (34211 [15421–54000] cells/cm² and 2.9 [2.0–6.9] days; P<0.0001 for both parameters). Primary isolated cells (pre-osteoblasts) from foxes had at 24 h post-confluence a median TNAP activity of 0.018 [0.011–0.023] U/min per mg protein. No differences were found among individuals.

As far as we are aware this is the first report of primary osteoblast culture from any fox species. Alkaline phosphatase is a key enzyme involved in mineralization and we are now optimising culture conditions to stimulate matrix mineralisation activity. These data provide a baseline from which bone scale at anatomical level can be related to isolated osteoblast behaviours in diverse canid species.