We tested this hypothesis by measuring bone formation by rat bone marrow stromal cells (BMSCs) transplanted ectopically in SCID mice using alginate hydrogels.
Kim et al. used coated zirconia scaffolds to augment calvarial defects in a rabbit model and reported closely matching values regarding porosity and density of the prepared scaffolds and regarding the amount of newly measured bone formation [20].
Samples were subsequently evaluated in duplicate for sRAGE by the Quantikine RAGE enzyme-linked immunoassay (R&D Systems, Minneapolis, MN); cross-linked N-telopeptides of type 1 (NTx) collagen, as a measure of bone resorption (Osteomark NTx ELISA/EIA, Wampole Laboratories, Princeton, NJ); and osteocalcin, as a measure of bone formation (ALPCO Diagnostics, Salem, NH).
No changes in calcium absorption were observed but there was a significant increase in kinetic rates of bone calcium accretion (P =.045) as well as in bone-specific alkaline phosphatase concentrations, a measure of bone formation (P =.03).
Importantly, the present results regarding BTM should not be extrapolated to any possible effect of TNF-α blocking therapy on radiographic progression in AS since no imaging method was used to measure new bone formation resulting in the formation of syndesmophytes and joint ankylosis.
To measure dynamic bone formation parameters, mice were injected intraperitoneally with calcein (Sigma, St Louis, MO, USA; 30 mg/kg body weight) and xylenol orange (Sigma, St Louis, MO, USA; 90 mg/kg body weight) on day 9 and day 2 before tissue harvest.
A significant anabolic response to loading was observed in static and dynamic microCT parameters as well as histomophometric measures of bone formation (Figs 2–5).
Bone-specific alkaline phosphatase (bALP) and osteocalcin (OC) were measured as bone formation indices.
Dynamic measures of bone formation at the femur diaphysis and vertebrae demonstrated that WFA increased MAR and BFR.
