Age‐related progression of bone marrow blood vessel ossification in rat and, potentially human, long bone (678.19)

Abstract

BACKGROUD: Bone perfusion and bone vessel location, density and function are associated with bone mass. We recently demonstrated ossification of bone vessels in rats. The objective of this study was to assess ossification with advancing age and to confirm ossification in human patients. METHODS: Femora from young (n=8) and old (n=8) male Fischer‐344 rats were examined to quantify patent vs. ossified and calcified vessels. Femora from additional young (n=5) and old (n=5) rats were analyzed for vessel ossification via µCT. Femoral vessels from a patient with ASVD and from rats were examined via microscopy. RESULTS: Isolated vessels (human and rat) had osteocyte lacunae on the surface. Patent vessel number was reduced (p<0.05) with age (0.47±0.05/mm2 vs. 0.29±0.05/mm2). Higher (p<0.05) volumes of ossified vessels were evident with age (0.01±0.01% vs. 0.49±0.11%). Calcified vessel volume/tissue volume (0.32 ±0.08% vs. 1.16±0.31%) and /patent vessel volume (17.2±5.9% vs. 62.4±15.5%) were augmented (p<0.05) in old rats. Ossified vessel number was higher (p<0.05) in old rats (0.07±0.01/mm2 vs. 0.19±0.04/mm2). CONCLUSIONS: For the first time, ossification of human bone marrow blood vessels was demonstrated. Ossification begins in youth and progresses with age, corresponding with a reduced number of patent vessels. Such pathology is presumably associated with bone disease.Grant Funding Source: Supported by NIH (NIAMS) Grant 1R15AR062882‐01