Non-destructive 3D microscopy in the study of patterns of biological adaptation among fossil and recent Homo

We apply non-destructive volumetric technique for evaluation of vascular net density in compact bone. Segmentation of Haversian canals and accurate estimation of their relative volume fraction gives the opportunity to estimate the density and capacity of the vascular system of the bone tissue in a proxy way. Radiological images of dorsal compact of medial and distal phalanges were studied (Neanderthals from Altai and Europe; CroMagnons; recent humans of Arctic and African origin). Results. High vascularization of compact clearly demonstrates that European Neanderthals and the majority of AMH were adapted to the Glacial Age. But Kostenki 14 (Eastern Europe) and Strashnaya 4 (Altai) have features in common with humans of recent tropic origin. Specimens of Neanderthals which lived in Altai region where glaciers never occurred are more diverse. Hypothetically the milder climate favored the existence of a wider adaptive norm reflecting patterns of former environments. Somewhat ambiguous morphological patterns of Denisova 9 and Okladnikov 2, 5 may reflect various episodes of Neanderthal migration to Siberia and their hybridization with people of tropical ancestry, most probably the early AMH. Chagyrskaya Neanderthal demonstrates a hyper-cold adaptation. Conclusion. Diversity in microstructural patterns of the Pleistocene people’s skeletal system gives evidence that both Neanderthals and CroMagnons were polymorphic in their adaptive reactions and presumably included both warm and cold adapted forms.

Does the osteon morphology depend on the body mass? A scaling study on macroscopic and histomorphometric differences between cow (Bos taurus) and sheep (Ovis aries)

The structure and geometry of bone depend on many biological and environmental factors. These factors affect the bone tissue's microstructure differently, and their interaction has not yet been fully elucidated. Our research investigated the effect of body mass on the macro- and microstructure of the compact bone. Therefore we analyzed the humerus and femur bones from females of 11 cows and 11 sheep at the age of 4–10 years. Both species have very similar dietary and locomotion patterns, but their body size and weight are very different. Within macroscopical analyzes of bones were observed ascending order of robustness index and bone diaphysis index. In both animals, plexiform and irregular Haversian bone tissues were identified in humerus and femur. Conversely, the dense Haversian tissue present only in cow above all in the femur. The most considerable interspecific osteonal difference between sheep and cow was in the osteon density, whose average value is 37% higher in the cow. The osteons of sheep humerus are almost circular, and osteons of cow femur are more elliptical. Within both species, the femoral osteons are elliptical than those of humerus. Despite the cow weighing more than 10 times the sheep, the measurements of osteons and Haversian canals, are very similar (the values of the ratio cow/sheep for these types are comprised from 1.04 to 1.86). Our findings indicate that the body mass does not affect the size of bone microstructure, probably more sensitive to other factors as a lifestyle and locomotor ability.

Cortical Bone Modifications after Radiotherapy: Cortex Porosity and Osteonal Changes Evaluated Over Time

Aiming to evaluate cortical bone microarchitecture and osteonal morphology after irradiation, twelve male New Zealand rabbits were used. The animals were divided: control group (no radiation-NIr); and 3 irradiated groups, sacrificed after: 7 (Ir7d); 14 (Ir14d) and 21 (Ir21d) days. A single radiation dose of 30 Gy was used. Computed microtomography analyzed the cortical microarchitecture: cortical thickness (CtTh), bone volume (BV), total porosity (Ct.Po), intracortical porosity (CtPo-cl), channel/pore number (Po.N), fractal dimension (FD) and degree of anisotropy (Ct.DA). After scan, osteonal morphology was histologically assessed by means: area and perimeter of the osteons (O.Ar; O.p) and of the Haversian canals (C.Ar; C.p). Microtomographic analysis were performed by ANOVA, followed by Tukey and Dunnet tests. Osteon morphology analyses were performed by Kruskal-Wallis, and test Dunn’s. Cortical thickness was significant difference (p<0.010) between the NIr and irradiated groups, with thicker cortex at Ir7d (1.15±0.09). The intracortical porosity revealed significant difference (p<0.001) between irradiated groups and NIr, with lower value for Ir7d (0.29±0.09). Bone volume was lower in Ir14d compared to control. Area and perimeter of the osteons were statistically different (p<0.0001) between NIr and Ir7d. Haversian canals also revealed lower values (p<0.0001) in Ir7d (80.57±9.3; 31.63±6.5) compared to NIr and irradiated groups. Cortical microarchitecture was affected by radiation, and the effects appear to be time-dependent, mostly regarding the osteons morphology at the initial days. Cortex structure in Ir21d revealed similarities to control suggesting that microarchitecture resembles normal condition after a period.

The effect of calcium phosphate biodegradable coatings of titanium implants on cell differentiation and apoptosis in rat bone tissue after experimental fracture

BACKGROUND: The effectiveness of bone repair is determined by the balance of proliferative and destructive factors in the fracture union site. It can be enhanced by using various nanostructured materials possessing osteoinductive properties, in particular titanium implants with biodegradable calcium phosphate coatings. The effects of these coatings on the state of stem cells, their differentiation and distribution in the repair zone is unknown. OBJECTIVE : To study the dynamics of proliferation, differentiation, and apoptosis of stem cells after experimental fracture followed by implantation of titanium implants with calcium phosphate coatings. METHODS: The localization of proliferation (PCNA) and differentiation (CD44 and osteocalcin) factors and apoptotic molecules (MDM2, p53, caspase-3) was studied in a rat femoral fracture model with implant placement. Titanium implant screws with bioactive calcium phosphate and hydroxyapatite coatings formed by plasma electrolytic oxidation were used in the study. Experimental rats were arranged into three groups (15 animals per group): control group; rats implanted with uncoated implants; and rats implanted with coated implants. Control rats were subject to a similar fracture as experimental ones and were allowed to heal conservatively. Rats from all groups were sampled on days 7, 14, and 30 after injury. RESULTS: Low-differentiated PCNA-, osteocalcin-, and CD44-immunopositive cells were localized around the implant in the inner layer of the periosteum, layer of outer circumferential lamellae, and connective tissue lining of haversian canals. The spatial density of cells expressing the above proliferation and differentiation factors, as well as that of MDM2-immunoreactive cells, increased on day 7 and decreased by day 30 after injury. The spatial density of apoptotic cells reached the maximum on day 14 after injury. They were mainly found in the inner layer of the periosteum and outer circumferential lamellae. p53- and caspase-3-positive cells occurred on the surface of the concentric lamellae surrounding haversian canals and under the periosteum. Their spatial density decreased by day 30 after injury. CONCLUSIONS: Calcium phosphate coatings stimulate cell proliferation at early stages of fracture restoration and apoptotic cell death at later stages. Coating components may provide positional information guiding the differentiation of mesenchymal stromal cells. A change in the activity of apoptotic factors, osteocalcin, and CD44 is caused by gene induction in response to the diffusion of calcium phosphate compounds from coating to surrounding tissue.

Variation of Streaming Potentials with Time under Steady Fluid Pressure in Bone

This paper investigates the streaming potentials’ behaviors when fluid flows through the micropores in bone. An experimental setup was developed for measuring the streaming potentials between two surfaces of a bone plate specimen. It was found that the streaming potentials measured increased almost linearly with time under a constant fluid pressure gradient, which does not agree with the prediction from the classical theory of streaming potentials. To explain the reasons associated with the results obtained, a theoretical model was proposed in which the electric charge densities on the inner surfaces of the capillary are unevenly distributed. A formula was developed for solving the model, and the solutions demonstrate that nonuniform accumulations of electric charges carried by the fluid on the inner surfaces of the microcanals in bone can induce streaming potentials which linearly increase with time during the driving air pressure holding period. This phenomenon represents the specific characteristics of bone. The solution implies that the streaming potentials in Haversian canals, lacunas and canaliculi are not affected by electro-viscous resistance in the bone fluid.

Subacute Exposure to Alcohol in Relation to Bone Microstructure of Mice

Our study aimed to investigate subacute exposure to alcohol in relation to bone microstructure of mice. Animals from experimental (E) group drank a solution composed of 15 % ethanol and water for 14 days (one remodeling cycle), while those from control (C) group drank only water. In the compact bone of E group, decreased bone formation and increased porosity were observed which corresponds with lower levels of serum alkaline phosphatase and glutathione. Alcohol significantly increased sizes of primary osteon's vascular canals and decreased those of secondary osteons, Haversian canals. Relative bone volume, bone mineral density (BMD), relative bone volume without marrow cavity were also lower in E group. On the contrary, trabecular bone microstructure did not differ significantly between E and C groups. Liver function test showed higher levels of alanine aminotransferase, aspartate aminotransferase in alcohol-fed mice. Serum calcium, phosphate were significantly lower in E group. According to our study, only changes in compact bone microstructure of mice following one remodeling cycle were observed due to both direct and indirect effects of alcohol.

Histomorphometric Analysis of Bone Density in Relation to Tactile Sense of the Surgeon During Dental Implant Placement

Introduction: A correct diagnosis and optimal treatment planning is essential for success in implant dentistry. Proper diagnosis of bone quality is an important part of the diagnostic procedure. Objective: The purpose of this study was to correlate the tactile sense of the surgeon in the assessment of bone density to the histomorphometric analysis of bone quality. Methods: In this study, 56 bone samples from 33 patients were harvested from implant sites with trephine drills. The samples were analyzed with Image J software. In the samples following parameters were measured: BV/TV, superficial cortical plate thickness, the number and thickness of haversian canals in cortical bone and the number, thickness and distance of trabecules in cancellous bone. The clinical hardness of bone during drilling was evaluated by surgeon according to Misch. GEE analysis with exchangeable correlation structure and linear model was used to evaluate the relationship between the tactile sense of the surgeon and histomorphometric parameters and all analysis was adjusted for two confounding variables: gender and location. Results: There were 51.79% implants in D2 samples and 48.21% in D3. Bone classification according to Misch was significantly correlated to distance of trabecules in cancellous bone (P-value=0.05), and shown marginally significant correlation with mean superficial cortical bone thickness (P-value =0.07) and number of haversian canals (P-value =0.005) in cortical bone. Discussion: There were differences between our results and others. The authors believed that these differences mainly are because of confounding factors, that in this study were eliminated. The clinical finding during surgery can approximately explain the histologic properties of bone. Conclusion: It is concluded that tactile sense of the surgeon can exhibit the histologic properties of the bone, and we are able to estimate the healing prognosis of the bone in implant placement.

Secondary osteons scale allometrically in mammalian humerus and femur

Intra-cortical bone remodelling is a cell-driven process that replaces existing bone tissue with new bone tissue in the bone cortex, leaving behind histological features called secondary osteons. While the scaling of bone dimensions on a macroscopic scale is well known, less is known about how the spatial dimensions of secondary osteons vary in relation to the adult body size of the species. We measured the cross-sectional area of individual intact secondary osteons and their central Haversian canals in transverse sections from 40 stylopodal bones of 39 mammalian species. Scaling analysis of our data shows that mean osteonal resorption area (negative allometry, exponent 0.23, R2 0.54, p < 0.005) and Haversian canal area (negative allometry, exponent 0.34, R2 0.45, p < 0.005) are significantly related to body mass, independent of phylogeny. This study is the most comprehensive of its kind to date, and allows us to describe overall trends in the scaling behaviour of secondary osteon dimensions, supporting the inference that osteonal resorption area may be limited by the need to avoid fracture in smaller mammalian species, but the need to maintain osteocyte viability in larger mammalian species.

Heterogeneity of Necrotic Changes between Cortical and Cancellous Bone in Mandibular Osteoradionecrosis: A Histopathological Analysis of Resection Margin after Segmental Mandibulectomy

Background. This study aimed to analyze differences in necrotic changes between cortical and cancellous bone in resection margins after segmental mandibulectomy for advanced mandibular osteoradionecrosis. Methods. Anteroposterior bone specimens from eleven patients who underwent segmental mandibulectomy with simultaneous free fibula flap reconstruction for advanced osteoradionecrosis were analyzed histopathologically for the presence of necrotic bone based on the presence of blood vessels within Haversian canals. Results. Ten of eleven (91%) cortices near the inferior border of the mandible at the anterior margins were necrotic. All cancellous bones at the anterior margins were viable. Seven of eleven (64%) cortices near the inferior border of the mandible at the posterior margins were necrotic. Three of eleven (27%) cancellous bones at the posterior margins were necrotic. Conclusion. Necrotic changes are more prevalent in cortices than in cancellous bones in mandibular osteoradionecrosis, probably due to a decrease of periosteal blood supply caused by radiotherapy.