Measurement Of Lumbar Bone Mineral Density And Body Composition In Healthy Female Cynomolgus Monkeys Based On QCT

ObjectiveFemale cynomolgus monkeys are commonly used in studies related to osteoporosis,and there is no evidence of age-related changes in volumetric bone mineral density(vBMD)and body composition measured using quantitative computed tomography(QCT)in nonhuman primates.This study aimed to describe changes in the characteristics of lumbar vBMD and body composition with age in healthy female cynomolgus monkeys,to calculate the accumulated bone loss rate(ABLR),to analyze the relationship between lumbar vBMD and body composition,and to investigate the precision of QCT measurements in cynomolgus monkeys.MethodsThe lumbar vBMD and body composition were measured using QCT in healthy female cynomolgus monkeys of different ages,and their age-related changes were described using cubic regression models.The correlations between the average lumbar vBMD and body composition were analyzed using Spearman rank correlation and multiple regression analysis.Thirty healthy female cynomolgus monkeys were selected to analyze the short-term in vivo precision of QCT measurements.Short-term in vivo precision was expressed as root-mean-square coefficient of variation(RMS-CV)or root-mean-square standard deviation.ResultsA total of 72 healthy female cynomolgus monkeys,aged 1-25 years,were included in this study.The average lumbar vBMD of female cynomolgus monkeys increased with age until the age of 10 years,around which it reached peak bone mass,with a decline after the age of 13 years.Psoas major density(PMD)and erector spinae density tended to decrease with age.The lean mass of the paravertebral muscles and abdominal adipose tissue increased with age until the age of 10 years,and showed a decreasing trend after the age of 15 years.The ABLRs in female cynomolgus monkeys in the premenopausal(13-19 years)and postmenopausal age groups(20-25 years)were -4.9% and -21.2%,respectively.Multiple regression analysis showed that age,PMD and subcutaneous adipose tissue(SAT)contributed positively to the average lumbar vBMD in animals aged ≤10 years,whereas in animals aged >10 years,only age contributed negatively to lumbar vBMD.The RMS-CV of the lumbar vBMD,paravertebral muscle tissue and abdominal adipose tissue in healthy female cynomolgus monkeys measured by QCT ranged from 0.47% to 1.60%,2.01-5.40% and 2.94-16.78%,respectively.ConclusionsAge-related changes in lumbar vBMD and body composition measured using QCT in healthy female monkeys showed similar trends to those in humans.Age,PMD and SAT may affect the lumbar vBMD in female cynomolgus monkeys.QCT revealed good precision in measuring lumbar vBMD in female cynomolgus monkeys.