A multimodal 3D imaging approach of pore networks in the human femur to assess age-associated vascular expansion and Lacuno-Canalicular reduction
Cellular communication in the mechanosensory osteocyte Lacuno-Canalicular Network (LCN) regulates bone tissue remodeling throughout life. Age-associated declines in LCN size and connectivity dysregulate mechanosensitivity to localized remodeling needs of aging or damaged tissue, compromising bone quality. Synchrotron radiation-based micro-Computed Tomography (SRμCT) and Confocal Laser Scanning Microscopy (CLSM) were employed to visualize LCN and vascular canal morphometry in an age series of the anterior femur (males n = 14, females n = 11, age range = 19-101, mean age = 55). Age-associated increases in vascular porosity were driven by pore coalescence, including a significant expansion in pore diameter and a significant decline in pore density. In contrast, the LCN showed significant age-associated reductions in lacunar volume fraction, mean diameter, and density, and in canalicular volume fraction and connectivity density. Lacunar density was significantly lower in females across the lifespan, exacerbating their age-associated decline. Canalicular connectivity density was also significantly lower in females but approached comparable declining male values in older age. Our data illuminate the trajectory and potential morphometric sources of age-associated bone loss. Increased vascular porosity contributes to bone fragility with aging, while an increasingly reduced and disconnected LCN undermines the mechanosensitivity required to repair and reinforce bone. Understanding why and how this degradation occurs is essential for improving the diagnosis and treatment of age-related changes in bone quality and fragility.
Janna M Andronowski
Mary E Cole
Reed A Davis
Gina R Tubo
Joshua T Taylor
David M L Cooper
Anat Rec (Hoboken)
. 2022 Sep 25. doi: 10.1002/ar.25089. Online ahead of print.
2022
English
Human growth hormone transgene expression increases the biomechanical structural properties of mouse vertebrae
aged rats; biomechanical properties; bone marrow compression; cortical bone; erythroid; fusion genes; growth-hormone; human; mice; Neurosciences & Neurology; Orthopedics; osteoblasts; transgenic mice; vertebrae
Study Design, Caudal vertebrae were obtained from male and female mice from two transgenic lines expressing an erythroid-specific human growth hormone-transgene construct, and gender-matched, age-matched, nontransgenic control mice. Objective. To characterize the effect of human growth hormone transgene expression on the biomechanical structural properties of caudal vertebrae in compression. Summary of Background Data. An increase in trabecular and cortical bone deposition caused by erythroid-specific human growth hormone transgene expression was demonstrated previously. Methods. Compression tests were performed on individual caudal vertebrae (Ca4, Ca5, Ca6) obtained from male and female mice from two transgenic lines (TG420 and TG450) and nontransgenic control mice. Two age groups were evaluated: 12 weeks old and 6 months old. The data were used to obtain axial stiffness, maximum load, and energy to failure. Results. Vertebrae from male TG420 transgenic mice produced significantly larger values for maximum load, energy to failure, and axial stiffness at both 12 weeks and 6 months in comparison with their age-matched nontransgenic male controls. Vertebrae from female TG420 transgenic mice produced similar responses at 6 months. Vertebrae from male TG450 transgenic mice showed significant increases in maximum load and energy to failure at 6 months. In general, the biomechanical properties of vertebrae were significantly larger in the 6-month age group than in the 12-week age group, and this increase was significantly greater in the transgenic mice than in the gender-matched control mice during the same time span. This process was also influenced by transgenic genotype and gender. Conclusions. Erythroid-specific production of human growth hormone in transgenic mice resulted in significant increases in biomechanical properties of their caudal vertebrae in compression. The changes in the biomechanical properties were influenced by genotype, age, and gender.
Steinke B; Patwardhan A G; Havey R M; King D
Spine
1999
1999-01
Journal Article
<a href="http://doi.org/10.1097/00007632-199901010-00002" target="_blank" rel="noreferrer noopener">10.1097/00007632-199901010-00002</a>
Trabecular Bone Structure in the Mandibular Condyles of Gouging and Nongouging Platyrrhine Primates
Anthropology; architecture; biomechanics; bone; callithrix-jacchus; callitrichids; cancellous; cortical bone; elastic principal directions; Evolutionary Biology; femoral-head; fossil record; iterative selection method; jaw functional morphology; marmosets; mechanical properties; tamarins; temporomandibular-joint
The relationship between mandibular form and biomechanical function is a topic of significant interest to morphologists and paleontologists alike. Several previous studies have examined the morphology of the mandible in gouging and nongouging primates as a means of understanding the anatomical correlates of this feeding behavior. The goal of the current study was to quantify the trabecular bone structure of the mandibular condyle of gouging and nongouging primates to assess the functional morphology of the jaw in these animals. High-resolution computed tomography scan data were collected from the mandibles of five adult common marmosets (Callithrix jacchus), saddle-back tamarins (Saguinus fuscicollis), and squirrel monkeys (Saimiri sciureus), respectively, and various three-dimensional morphometric parameters were measured from the condylar trabecular bone. No significant differences were found among the taxa for most trabecular bone structural features. Importantly, no mechanically significant parameters, such as bone volume fraction and degree of anisotropy, were found to vary significantly between gouging and nongouging primates. The lack of significant differences in mechanically relevant structural parameters among these three platyrrhine taxa may suggest that gouging as a habitual dietary behavior does not involve significantly higher loads on the mandibular condyle than other masticatory behaviors. Alternatively, the similarities in trabecular architecture across these three taxa may indicate that trabecular bone is relatively unimportant mechanically in the condyle of these primates and therefore is functionally uninformative. Am J Phys Anthropol 141:583-593, 2010. (C) 2009 Wiley-Liss, Inc.
Ryan T M; Colbert M; Ketcham R A; Vinyard C J
American Journal of Physical Anthropology
2010
2010-04
Journal Article
<a href="http://doi.org/10.1002/ajpa.21178" target="_blank" rel="noreferrer noopener">10.1002/ajpa.21178</a>