Transcript – Inflamm-Aging and Osteopenia in a Rodent Model of Spinal Cord Injury

Bone loss significantly affects physical health and quality of life for people living with a spinal cord injury, people with a spinal cord injury or ISCI have a 30 to 40 percent decrease in bone mineral density in the legs following injury, leaving them up to 104 times more likely than the general population to have a fracture by the age of 50. With post fracture complications occurring in 54 per cent of cases, seeing just bone loss is further exacerbated as people with spinal cord injury age. There is a relatively slow rate of decline in bone mineral density beginning at age 40 and continuing throughout adult life. Yet despite these significant consequences of reduced bone health, very few labs have focused on this effect of spinal cord injury. The present study begins to address this. We hypothesized that an SCA-induced reduction in weight bearing on the high Nîmes would further exacerbate age induced bone loss. To test this, young and old male and female mice were given a moderate spinal contusion injury, which results in temporary loss of locomotor function. Their recovery was then monitored for 28 days. Post injury and bone volume was measured at the end of the 28-day period. We found that all mice recovered weight supported stepping after FCI. Not surprisingly, the mice also showed decreased activity with age. But there was no effective FCI looking at rearing. However, both FCI and age reduced this behavior. Both FCI and age also reduced bone volume. And when we looked at the relationship between bone volume and rearing, we found a significant positive correlation. Increased rearing and increased activity were associated with increased bone volume. These data suggest that physical therapy can reduce bone loss after FCI, but the parameters of intervention will be critical. Current therapies after S.I use partial weight bearing and they do not stabilize or reverse bone loss. Our studies suggest that complete loading of the hind limbs, which would be emphasized in rearing, is critical for the preservation of bone. Our future studies will focus on the development of creative therapies that can simulate loading in people with reduced weight bearing ability.