-
Journal of Forensic Sciences Jul 2020Aging adult skeletal material is a crucial component of building the biological profile of unknown skeletal remains, but many macro- and microscopic methods have...
Aging adult skeletal material is a crucial component of building the biological profile of unknown skeletal remains, but many macro- and microscopic methods have challenges regarding accuracy, precision, and replicability. This study developed a volumetric method to visualize and quantify histological remodeling events in three dimensions, using a two-dimensional serialized approach that applied circular polarizing microscopy and geographic information systems protocols. This approach was designed as a tool to extend current histological aging methodologies. Three serial transverse sections were obtained from a human femoral midshaft. A total sample size of 6847 complete osteons from the three sections was identified; 1229 osteons connected between all sections. The volume of all connected osteons was interpolated using ArcGIS area calculations and truncated cone geometric functions. Each section was divided into octants, and two random samples of 100 and of 30 connected osteons from each octant were generated. Osteon volume was compared between the octants for each random sample using ANOVA. Results indicated that the medial aspect had relative uniformity in osteon volume, whereas the lateral aspect showed high variability. The anterolateral-lateral octant had significantly smaller osteon volume, whereas the posterior-posterolateral octant had significantly larger osteon volume. Results also indicated that a minimum of 100 osteons is statistically more robust and more representative of normal osteon distribution and volume; the use of 30 osteons is insufficient. This research has demonstrated that osteon volume can be interpolated using spatial geometry and GIS applications and may be a tool to incorporate into adult age-at-death estimation techniques.
Topics: Age Determination by Skeleton; Bone Remodeling; Femur; Forensic Anthropology; Geographic Information Systems; Haversian System; Humans; Image Processing, Computer-Assisted; Microscopy
PubMed: 32092159
DOI: 10.1111/1556-4029.14305 -
Bone Dec 2021Bone remodeling in the elderly is no longer balanced. As a result, the morphologies and mechanical properties of bone at different scales will change. These changes...
BACKGROUND
Bone remodeling in the elderly is no longer balanced. As a result, the morphologies and mechanical properties of bone at different scales will change. These changes would affect the mechanical responses of bone, which might exacerbate the imbalance of bone remodeling and even cause age-related bone diseases.
METHODS
Considering those changes, multiscale finite element (FE) models of bone in the young and the elderly were developed that included macroscale (proximal femur), mesoscale (cortical bone), microscale (Haversian system) and sub-microscale (osteocyte-lacuna-canaliculus-extracellular matrix system, OLCES). The stress and strain distributions at different scales and transmissions among different scales were investigated.
RESULTS
The stresses of the elderly at macroscale, mesoscale and microscale were higher than those in the young by 23.7%, 62.5% and 8.0%, respectively, and the stresses of the elderly and the young at sub-microscale were almost the same. The strain of the elderly at macroscale, mesoscale, microscale and sub-microscale were higher than those in the young by 48.6%, 56.8%, 11.9% and 25.1%, respectively. The stress and strain transmission rates (ηand η) from mesoscale to microscale were decreased by 1.8%, and 2.5% than those from macroscale to mesoscale in the elderly, respectively; but increased by 13.8%, and 4.7% in the young, respectively. η from microscale to sub-microscale in the elderly was higher than that in the young by 21.3%.
CONCLUSIONS
Degeneration of cortical bone mechanical property in the elderly causes increases in stress and strain at macroscale and mesoscale. The reduction of lacunar number in the elderly is not conducive to the mechanical transmission from mesoscale to microscale. The differences in stress and strain at microscale between the young and the elderly are smaller than those at macroscale or mesoscale. The strain stimulus sensed by osteocyte in the elderly is not weakened compared with that in the young.
Topics: Aged; Bone and Bones; Cortical Bone; Femur; Finite Element Analysis; Haversian System; Humans; Stress, Mechanical
PubMed: 34280582
DOI: 10.1016/j.bone.2021.116125 -
International Journal of Implant... Apr 2022Many points concerning the structure of osseointegration and the surrounding jaw bone remain unclear, and its optimal histological form has yet to be identified. The aim...
PURPOSE
Many points concerning the structure of osseointegration and the surrounding jaw bone remain unclear, and its optimal histological form has yet to be identified. The aim of this study was to clarify the structural characteristics of peri-implant jaw bone on the micro- and nano-scales by quantitatively evaluating bone quality.
METHODS
Five samples of human mandibular bone containing dental implants and one dentate sample that had been in place for some years while the donors were still alive were collected. Bulk staining was performed, and 100-μm-thick polished specimens were prepared. The osteon distributions in peri-implant bone and mandibular cortical bone were measured, after which alignment analysis of biological apatite (BAp) crystallites and anisotropy analysis of collagen fiber orientation using second-harmonic generation imaging were carried out.
RESULTS
Osteons in the vicinity of the implant body ran parallel to it. In the cortical bone at the base of the mandible, however, most osteons were oriented mesiodistally. The preferential alignment of BAp crystallites was generally consistent with osteon orientation. The orientation of collagen fibers in peri-implant jaw bone resembled the concentric rings seen in normal cortical bone, but there were also fibers that ran orthogonally across these concentric fibers.
CONCLUSIONS
These results suggest that the mechanical strain imposed by implants causes the growth of cortical bone-like bone in areas that would normally consist of cancellous bone around the implants, and that its structural characteristics are optimized for the load environment of the peri-implant jaw bone.
Topics: Apatites; Cadaver; Collagen; Dental Implants; Humans; Mandible; Osseointegration
PubMed: 35411479
DOI: 10.1186/s40729-022-00417-3 -
International Journal of Biological... 2021Fibroblast growth factors (FGFs) include a large family of growth factors that play a critical role in maintaining bone homeostasis, but the specific role of its members...
Fibroblast growth factors (FGFs) include a large family of growth factors that play a critical role in maintaining bone homeostasis, but the specific role of its members such as FGF7 does not well understand. Osteoblasts are a kind of major cells essential for bone formation. Osteoblasts interact with one another to create the unique structure of osteons. The well-connected osteons constitute the cortical bone. As an early osteocyte marker that triggers actin cytoskeleton dynamics, E11 is essential for osteoblasts' dendrites formation. However, the upstream which regulates E11 is mainly unknown. The purpose of this study was to examine the influence of FGF7 on the expression and the distribution of E11 in osteoblasts, which mediated osteoblasts' processes formation and gap junctional intercellular communication (GJIC) partly through connexin43 (Cx43). We first demonstrated that FGF7 increased the expression of E11 in osteoblasts. We then showed that FGF7 promoted osteoblasts' dendrites elongation and functional gap junctions formation. Furthermore, E11 interacted directly with Cx43 in primary osteoblasts. MAPK pathway and PI3K-AKT pathway were involved in the effect of FGF7. Our results shed light on the unique role of FGF7 on osteoblasts, which may indicate that FGF7 plays a more significant role in the later stages of bone development and homeostasis.
Topics: 3T3 Cells; Animals; Cell Communication; Connexin 43; Fibroblast Growth Factor 7; Ligands; MAP Kinase Signaling System; Membrane Glycoproteins; Mice; Osteoblasts
PubMed: 34671204
DOI: 10.7150/ijbs.65240 -
Wiadomosci Lekarskie (Warsaw, Poland :... 2021The aim: To evaluate morphological changes in long tubular bones of mature rats under the influence of experimental hyperglycemia.
OBJECTIVE
The aim: To evaluate morphological changes in long tubular bones of mature rats under the influence of experimental hyperglycemia.
PATIENTS AND METHODS
Materials and methods: The study was conducted on 140 nonlinear white male rats divided into two groups. The experimental group included rats that were introduced into a state of hyperglycemia by a single intraperitoneal injection of an alloxan dihydrate solution at a dose of 150 mg / kg body weight in 0.9% sodium chloride. The control group included rats that were injected with a similar volume of 0.9% sodium chloride one time intraperitoneally. The animals were taken out of the experiment on the 2nd, 30th, 60th, 90th, 120th, 150th and 180th day. Right and left femur and humerus were studied by morphometric and histological methods.
RESULTS
Results: Under conditions of prolonged uncontrolled hyperglycemia in mature rats, there is a slowdown in the growth rate of length and thickness of femur and humerus. This is indicated by a significant decrease in the length of bone and its diaphyses, as well as by a decrease in the cross-sectional area of the diaphysis, the width of the proximal and distal epiphyses, starting from 120 and 90 days of the experiment, respectively. The relative area of trabecular tissue, thickness of trabeculae and epiphyseal cartilage decreases in comparison with animals of the control group. The diameter of osteons and their channels increases in cortical tissue. Changes in the microarchitecture of the trabecular and cortical compartments of femur and humerus under conditions of hyperglycemia are similar and are characterized by a reduced bone mass, bone disorder progression and remodeling disorders.
CONCLUSION
Conclusions: Prolonged uncontrolled experimental hyperglycemia leads to slow growth of femur and humerus in mature rats, which is accompanied by an increase in microarchitecture disorder of the trabecular and cortical compartments, causing miniaturization of bones and, consequently, violation of their biomechanical properties and increased risk of fractures.
Topics: Animals; Bone Density; Bone and Bones; Femur; Fractures, Bone; Hyperglycemia; Male
PubMed: 34725275
DOI: No ID Found -
The Journal of Experimental Biology Aug 2023Bone adaptation to mechanical loading happens predominantly via modeling and remodeling, but the latter is poorly understood. Haversian remodeling (cortical bone...
Bone adaptation to mechanical loading happens predominantly via modeling and remodeling, but the latter is poorly understood. Haversian remodeling (cortical bone replacement resulting in secondary osteons) is thought to occur in regions of low strain as part of bone maintenance or high strain in response to microdamage. However, analyses of remodeling in primates have revealed an unappreciated association with the number of daily load cycles. We tested this relationship by raising 30 male domestic rabbits (Oryctolagus cuniculus) on disparate diets from weaning to adulthood (48 weeks), facilitating a naturalistic perspective on mandibular bone adaptation. A control group consumed only rabbit pellets and an 'overuse' group ate hay in addition to pellets. To process hay, which is tougher and stiffer, rabbits increase chewing investment and duration without increasing bite force (i.e. corpus mean peak strain is similar for the two foods). Corpus remodeling in overuse rabbits was ∼1.5 times that of controls, measured as osteon population density and percentage Haversian bone. In the same subjects, there was a significant increase in overuse corpus bone formation (ratio of cortical area to cranial length), consistent with previous reports on the same dietary manipulation and bone formation in rabbits. This is the first evidence that both modeling and remodeling are simultaneously driven by the number of load cycles, independent of strain magnitude. This novel finding provides unique data on the feeding apparatus, challenges traditional thought on Haversian remodeling, and highlights the need for experimental studies of skeletal adaptation that examine mechanical factors beyond strain magnitude.
Topics: Animals; Rabbits; Male; Bone Remodeling; Mandible; Haversian System; Lagomorpha
PubMed: 37439268
DOI: 10.1242/jeb.245942 -
Physiological Loading-Induced Interstitial Fluid Dynamics in Osteon of Osteogenesis Imperfecta Bone.Journal of Biomechanical Engineering Aug 2021Osteogenesis imperfecta (OI), also known as "brittle bone disease," is a genetic bone disorder. OI bones experience frequent fractures. Surgical procedures are usually...
Osteogenesis imperfecta (OI), also known as "brittle bone disease," is a genetic bone disorder. OI bones experience frequent fractures. Surgical procedures are usually followed by clinicians in the management of OI. It has been observed physical activity is equally beneficial in reducing OI bone fractures in both children and adults as mechanical stimulation improves bone mass and strength. Loading-induced mechanical strain and interstitial fluid flow stimulate bone remodeling activities. Several studies have characterized strain environment in OI bones, whereas very few studies attempted to characterize the interstitial fluid flow. OI significantly affects bone micro-architecture. Thus, this study anticipates that canalicular fluid flow reduces in OI bone in comparison to the healthy bone in response to physiological loading due to altered poromechanical properties. This work attempts to understand the canalicular fluid distribution in single osteon models of OI and healthy bone. A poromechanical model of osteon is developed to compute pore-pressure and interstitial fluid flow as a function of gait loading pattern reported for OI and healthy subjects. Fluid distribution patterns are compared at different time-points of the stance phase of the gait cycle. It is observed that fluid flow significantly reduces in OI bone. Additionally, flow is more static than dynamic in OI osteon in comparison to healthy subjects. This work attempts to identify the plausible explanation behind the diminished mechanotransduction capability of OI bone. This work may further be extended for designing better biomechanical therapies to enhance the fluid flow in order to improve osteogenic activities in OI bone.
Topics: Osteogenesis Imperfecta
PubMed: 33834233
DOI: 10.1115/1.4050818 -
Biomechanics and Modeling in... Oct 2020Mechanical loading-induced fluid flow in lacunar-canalicular space (LCS) of bone excites osteocyte cells to release signalling molecules which initiate osteo-activities....
Mechanical loading-induced fluid flow in lacunar-canalicular space (LCS) of bone excites osteocyte cells to release signalling molecules which initiate osteo-activities. Theoretical models considered canaliculi as a uniform and symmetrical space/channel in bone. However, experimental studies reported that canalicular walls are irregular and curvy resulting in inhomogeneous fluid motion which may influence the molecular transport. Therefore, a new mathematical model of LCS with curvy canalicular walls is developed to characterize cantilever bending-induced canalicular flow behaviour in terms of pore-pressure, fluid velocity, and streamlines. The model also analyses the mobility of signalling molecules involved in bone mechanotransduction as a function of loading frequency and permeability of LCS. Inhomogeneous flow is observed at higher loading frequency which amplifies mechanotransduction; nevertheless, it also promotes trapping of signalling molecules. The effects of shape and size of signalling molecules on transport behaviour are also studied. Trivially, signalling molecules larger in size and weight move slower as compared to molecules small in size and weight which validates the findings of the present study. The outcomes will ultimately be useful in designing better biomechanical exercise in combination with pharmaceutical agents to improve the bone health.
Topics: Adenosine Triphosphate; Animals; Biological Transport; Biomechanical Phenomena; Computer Simulation; Dinoprostone; Haversian System; Mice; Motion; Nitric Oxide; Porosity; Pressure; Signal Transduction; Tibia
PubMed: 32112154
DOI: 10.1007/s10237-020-01314-7 -
Tissue Engineering. Part C, Methods Dec 2022The characterization of diffusion through biological tissues has played an important role in fundamental medical research and product development. Understanding the...
The characterization of diffusion through biological tissues has played an important role in fundamental medical research and product development. Understanding the diffusion phenomena allows for the identification of new concepts in fundamental science, evolving medical knowledge and improving future standards and protocols. To illustrate, the structure of cortical bone changes upon the onset of osteoporosis, altering the limited porous compartment through which nutrients and essential signaling molecules travel to bone cells. Estrogen hormone replacement therapy (HRT) is one of the gold standard treatments to attempt to mitigate the effects that this structural change exerts in menopausal osteoporosis patients; however, HRT effectiveness is often variable in these patients, likely due to variability in bone structure and physiology, and thus transport rates. Scientists have studied diffusion in cortical bone tissue for decades. Current methodological standards include fluorescence recovery after photobleaching and computed tomography finite element analysis. Both techniques limit areas of tissue to microscale (1-100 μm) analysis-only examining a few osteocytes within the structure at a time-and adopt assumptions that oversimplify tissue structure and transport phenomena. Also, the range of diffusion tracers is limited by the sensitivities of the analytical equipment, typically requiring tracer concentrations in the micromolar range. Herein is described a novel device for directly assessing the diffusion coefficient of H-estradiol at 37°C in macroscale osteonal bone specimens (1.4 cm)-assessing a much larger portion of the total tissue than previously reported-while using radioisotope tracers for much higher sensitivity, thus achieving physiologically relevant estradiol concentrations. The current diffusion chamber device represents a cost-effective and validated method to mitigate these shortcomings. The device provides long-term diffusion data through macroscale (greater than 1 mm) tissue areas, presenting a more physiologically accurate way to assess cortical bone diffusion. The device can assess solute diffusion through other tissues or materials and may easily be scaled up to run multiple diffusion experiments simultaneously. Impact statement The diffusion chamber device represents a cost-effective and validated method to assess solute diffusion through solid materials. Specifically, it demonstrates that this novel device provides long-term diffusion data through macroscale tissue samples at nanomolar concentrations, presenting a precise way to address the effects of tissue structures on diffusion. This device can be applied to other tissues or engineered materials, offering a methodology that is easily scaled up to allow simultaneous assessment of multiple material samples.
Topics: Humans; Biological Transport; Diffusion; Bone and Bones; Osteoporosis; Estradiol
PubMed: 36094112
DOI: 10.1089/ten.TEC.2022.0129 -
Journal of Anatomy Jun 2021Lacking fur, living in eusocial colonies and having the longest lifespan of any rodent, makes naked mole-rats (NMRs) rather peculiar mammals. Although they exhibit a...
Lacking fur, living in eusocial colonies and having the longest lifespan of any rodent, makes naked mole-rats (NMRs) rather peculiar mammals. Although they exhibit a high degree of polymorphism, skeletal plasticity and are considered a novel model to assess the effects of delayed puberty on the skeletal system, scarce information on their morphogenesis exists. Here, we examined a large ontogenetic sample (n = 76) of subordinate individuals to assess the pattern of bone growth and bone microstructure of fore- and hindlimb bones by using histomorphological techniques. Over 290 undecalcified thin cross-sections from the midshaft of the humerus, ulna, femur, and tibia from pups, juveniles and adults were analyzed with polarized light microscopy. Similar to other fossorial mammals, NMRs exhibited a systematic cortical thickening of their long bones, which clearly indicates a conserved functional adaptation to withstand the mechanical strains imposed during digging, regardless of their chisel-tooth predominance. We describe a high histodiversity of bone matrices and the formation of secondary osteons in NMRs. The bones of pups are extremely thin-walled and grow by periosteal bone formation coupled with considerable expansion of the medullary cavity, a process probably tightly regulated and adapted to optimize the amount of minerals destined for skeletal development, to thus allow the female breeder to produce a higher number of pups, as well as several litters. Subsequent cortical thickening in juveniles involves high amounts of endosteal bone apposition, which contrasts with the bone modeling of other mammals where a periosteal predominance exists. Adults have bone matrices predominantly consisting of parallel-fibered bone and lamellar bone, which indicate intermediate to slow rates of osteogenesis, as well as the development of poorly vascularized lamellar-zonal tissues separated by lines of arrested growth (LAGs) and annuli. These features reflect the low metabolism, low body temperature and slow growth rates reported for this species, as well as indicate a cyclical pattern of osteogenesis. The presence of LAGs in captive individuals was striking and indicates that postnatal osteogenesis and its consequent cortical stratification most likely represents a plesiomorphic thermometabolic strategy among endotherms which has been suggested to be regulated by endogenous rhythms. However, the generalized presence of LAGs in this and other subterranean taxa in the wild, as well as recent investigations on variability of environmental conditions in burrow systems, supports the hypothesis that underground environments experience seasonal fluctuations that may influence the postnatal osteogenesis of animals by limiting the extension of burrow systems during the unfavorable dry seasons and therefore the finding of food resources. Additionally, the intraspecific variation found in the formation of bone tissue matrices and vascularization suggested a high degree of developmental plasticity in NMRs, which may help explaining the polymorphism reported for this species. The results obtained here represent a valuable contribution to understanding the relationship of several aspects involved in the morphogenesis of the skeletal system of a mammal with extraordinary adaptations.
Topics: Animals; Bone Development; Femur; Humerus; Mole Rats; Osteogenesis; Tibia; Ulna
PubMed: 33305850
DOI: 10.1111/joa.13381