Bone Components Research Articles

In Vitro Preparation and Evaluation of Alendronate-modified Hyaluronic acid-based Nanomicelles as a Bone-Targeted Drug Delivery System

Nanomicelles based on Hyaluronic acid (HA), a linear polysaccharide with high affinity to the CD44 receptor on cancerous cells, offer considerable potential to transport drugs to the target tissue while reducing exposure to normal tissues. The high affinity of alendronate (ALN) to hydroxyapatite crystals, the crucial component of bone, makes it an ideal candidate for bone-targeted delivering therapeutic nanoparticles. Here, we developed targeted and self-assembled nanocarriers by modifying HA nanomicelles with ALN to attach to hydroxyapatite. Curcumin (CUR), as a hydrophobic model drug, was used to evaluate the efficiency of developed nanomicelles. The size of blank and CUR-loaded nanomicelles was below 200 nm and their critical micelle concentrations were in the range of 38 μg/ml, which is suitable for delivery to bone tissue. The CUR-loaded ALN-HA-AC (CUR@ALN-HA-AC) nanomicelles showed a two-step release pattern, a first accelerated release period (12% in 1 h) followed by a sustained release (65% up to 50 h). The hydroxyapatite affinity experiment indicated that CUR@ALN-HA-AC nanomicelles exhibited significantly high affinity to the bone. Cytotoxicity studies on MG-63 cell lines demonstrated that CUR-loaded micelles exhibited much higher cytotoxic activity compared to free CUR, indicating that encapsulation in HA-ALN-AC micelles significantly enhanced the tumor cell-killing ability of CUR.

Bone Marrow and Metabolic Bone Disease.

The bone marrow represents one of the largest organs in the body, with a relevant metabolic role that continues to be investigated. Numerous studies have focused on marrow adipose tissue (MAT). Evidence indicates that the bone marrow adipocytes do not only work as storage tissue but also consist of endocrine and paracrine cells, with the potential to contribute to local and systemic metabolism. MAT plays a role in bone health through its interaction with the other components of bone. Many metabolic disorders (osteoporosis, obesity, diabetes) have a complex and still not well-established or understood relationship with bone health. This article surveys the literature on the relationship of bone marrow and metabolic disorders, and how it is being studied using imaging techniques, with a special focus on bone health.

Distraction of longitudinally split fragments using the Ilizarov method: a series of clinical cases of treating partial bone defects

Background. The Ilizarov method is a recognized technique for treating severe skeletal injuries, allowing for a comprehensive restoration of both bone and soft tissue components. Despite the fact that bone lengthening and transport are widely known techniques, distraction of a longitudinally split fragment is still used extremely rarely. The aim of the study is to describe a series of clinical cases involving patients operated on using this technique. Methods. We present a series of observations of five patients who underwent distraction of a longitudinally split fragment using the Ilizarov method between January 2006 and December 2022. Clinical information was obtained from case histories, all surgical interventions were documented. Postoperative examination was performed using radiography. Results. A case series demonstrates the successful application of this technique for reconstruction of partial bone defects resulting from trauma or osteomyelitis. The study included five patients (4 men and 1 woman) who underwent surgery 4.8-34.0 months after trauma for a partial defect of the proximal tibia ranging from 4 to 8 cm in length. Distraction was performed in different directions along the sagittal and longitudinal axes. The time of external fixation ranged from 3.5 to 4.8 months, the external fixation index ranged from 0.49 to 1.22. The ASAMI (Association for the Study and Application of the Methods of Ilizarov) functional score at the follow-up examination was excellent in all five patients. The ASAMI bone tissue assessment showed excellent results in all patients, except for one patient with residual equinus (good result). No other complications were reported. Conclusions. The Ilizarov method provides a minimally invasive and comprehensive approach to the elimination of partial bone defects, affecting simultaneously the skeletal and soft tissue components. Due to the longitudinal splitting during fragment transport and distraction osteogenesis, this method promotes bone and tissue regeneration and helps to avoid a volumetric bone defect and more complex segmental bone transport. Moreover, the role of transverse transport of the tibial cortex increases in the treatment of peripheral arterial diseases.

Fetal Vertebral Chondrostasis—Significance of Excessive Cartilage in Vertebral Bodies of Newborns

Introduction: We describe an abnormality in fetal and neonatal vertebral bodies whose most conspicuous characteristic is an increase in cartilaginous matrix within cancellous osseous trabeculae. We have termed this finding fetal chondrostasis (FC). Methods: We initiated a retrospective review of autopsy reports in which this condition had been prospectively diagnosed during a 36-year period. The Chalkley point counting method was applied to histologic sections of vertebral bodies to assess the relative components of cartilage, bone, and bone marrow. The results were compared to those of three control groups whose causes of death were prematurity, birth trauma, and infection. Results: We found that on average, the cartilaginous content in the FC group was considerably greater in both preterm and term infants when compared to controls. FC seemed to evolve from diminished activity in the cartilaginous growth zone resulting in formation of excessively broad cartilaginous columns. These subsequently suffered from delayed resorption following their incorporation within cancellous bony trabeculae. Conclusion: Excess cartilage within cancellous bone of vertebral centra in newborns is merely one aspect of disturbed intrauterine osseous development but is seemingly more readily discernible than other features at this site. The most common clinical correlates for FC were multiple congenital anomalies, congenital heart disease, intrauterine growth retardation, prematurity, and certain maternal factors.

Corrosion Behavior and Biological Properties of ZK60/HA Composites Prepared by Laser Powder Bed Fusion.

Magnesium alloy ZK60 shows great promise as a medical metal material, but its corrosion resistance in the body is inadequate. Hydroxyapatite (HA), the primary inorganic component of human and animal bones, can form chemical bonds with body tissues at the interface, promoting the deposition of phosphorus products and creating a dense calcium and phosphorus layer. To enhance the properties of ZK60, HA was added to create HA/ZK60 composite materials. These composites, fabricated using the advanced technique of LPBF, demonstrated superior corrosion resistance and enhanced bone inductive capabilities compared to pristine ZK60. Notably, the incorporation of 3 wt% led to a significant reduction in bulk porosity, achieving a value of 0.8%. The Ecorr value increased from -1.38 V to -1.32 V, while the minimum Icorr value recorded at 33.9 μA·cm-2. Nano-HA achieved the lowest volumetric porosity and optimal corrosion resistance. Additionally, these composites significantly promoted osteogenic differentiation in bone marrow stromal cells (BMSCs), as evidenced by increased alkaline phosphatase (ALP) activity and robust calcium nodule formation, highlighting their excellent biocompatibility and osteo-inductive potential. However, when increasing the HA content to 6 wt%, the bulk porosity rose significantly to 3.3%. The Ecorr value was -1.3 V, with the Icorr value being approximately 50 μA·cm-2. This increase in porosity and weaker interfacial bonding, ultimately accelerated electrochemical corrosion. Therefore, a carefully balanced amount of HA significantly enhances the performance of the ZK60 magnesium alloy, while excessive amounts can be detrimental.

Assessment of vitamin D status in obese and non-obese patients: A case-control study

BackgroundVitamin D is an essential component of healthy bones and its deficiency is widespread in obese patients. Through our study, we aimed to look into vitamin D status in obese and non-obese patients and determine its association with hypertension, glucose levels, and lipid profiles. Patients and methodsA case-control study was laid out to compare serum Vitamin D levels between obese patients and controls. Obese patients (n= 67) over 18 years old were recruited from our Endocrinology-Diabetology and Nutrition department between March 2018 and September 2023. Controls (n = 60) were randomly assigned and were matched for age, sex, glycated hemoglobin, ethnicity, and geographic area. The levels of Vitamin D in the serum were determined in obese patients and non-obese controls. ResultsAverage serum Vitamin D concentration was established in both groups, reaching 10,41±4,2 ng/ml in obese patients and 15,14±6,1 ng/ml in the control group. The mean serum Vitamin D was significantly lower in the obese group (p = 0,000). A positive correlation was noticed between body fat and serum Vitamin D (p < 0,05). A significant correlation between vitamin D status and glycated hemoglobin in the obese group (p = 0,047) was found, whereas it was insignificant in the control group (p = 0,966). In addition, the correlation between vitamin D, blood pressure, and body mass index was significant (p= 0.004) as well as between vitamin D and triglycerides (p= 0.015) and cholesterol (p= 0.014). ConclusionVitamin D deficiency is common in obese patients, as highlighted by our study, which is in line with other findings. This may be explained by the fact that vitamin D must be supplied at a greater volume in obese patients. A significant correlation between BMI, vitamin D, glycated hemoglobin, blood pressure, triglycerides, and total cholesterol was found. The pathophysiology behind this association is complex. Further research is needed to clarify the relationship between vitamin D, adipose tissue, and the other components of metabolic syndrome.

The Application of Magnetic Resonance Imaging in the Early and Accurate Diagnosis of Hip Joint Avascular Necrosis.

Introduction Avascular necrosis (AVN) is characterized by the death (necrosis) of cellular bone components in the subchondral bone or epiphysis due to a lack of or an interruption of the blood supply. In routine practice, AVN is most frequently encountered in the femoral head. In this study, we aim to evaluate the application of magnetic resonance imaging (MRI) in the early and accurate diagnosis of hip joint AVN. Materials and methods This was a retrospective, cross-sectional study conducted in the Department of Radiodiagnosis of Dr. D. Y. Patil tertiary care hospital, Pimpri, Pune, India. We studied 30 patients with complaints of pain and associated limping who underwent primary radiograph analysis of the hip joint, followed by MRI. Results We assessed 30 patients (45 hip joints) using plain radiography and MRI. Of the 45 hips, we could diagnose AVN in 28 hips (62.2%) using plain radiography, but we could not diagnose it in 17 hips (37.8%), whereas we were able to diagnose AVN in all hips (100%) using MRI. Forty percent of the patients (n = 12) were on steroids, 26.7%(n = 8) were chronic alcoholics, and 16.7% (n = 5) were idiopathic. The other less common causes were a history of trauma or fracture of the neck of the femur (n = 3) and sickle cell disease (n = 2).Of the 45 hips of the 30 patients studied, 15 patients had bilateral disease affecting a total of 30 hips (66.7%), and 15 patients had unilateral disease affecting a total of 15 hips (33.4%). Of the 30 hips (bilateral disease), five (13.3%) contralateral hips were clinically occult and were incidentally diagnosed with AVN. Conclusion The assessment of AVN based solely on plain radiography can miss vital information in stages II and III (Ficat and Arlet classification). Due to its multiplanar capability, superior spatial resolution, and better tissue characterization, MRI is very sensitive and able to detect femoral head AVN early and promptly in cases that are radiograph-negative or otherwise clinically unsuspected.

The deterioration of microstructure and biochemical components in cancellous bone characterizing by the photoacoustic microscopy imaging

Abstract Background/Objective: Osteoporosis is mainly characterized by a deterioration of microstructure and a loss of biochemical components in bone tissues. Developing an imaging technique for measuring bone tissue microstructure and the biochemical components is of great significance for the early diagnosis of osteoporosis. Photoacoustic microscopy (PAM) has the advantage of high optical resolution and the potential to diagnose osteoporosis. In this study, we investigated the feasibility of the photoacoustic microscopy (PAM) technique for bone tissue imaging, and the deterioration of microstructure and biochemical components in cancellous bone was characterized by the PAM. Statement of Contribution/Methods: We performed the optical-resolution photoacoustic microscopy (OR-PAM) for bone tissue imaging and the trabecular microstructure and hydroxyapatite (HAP) were degraded by immersion in JYBL-I solution. The PAM imaging method was developed for the measurement of the surface and subsurface of cancellous bone with a high resolution. Specifically, a 532 nm pulse laser was used to excite the PA signal from the bone. The PA signal sampling frequency was 80 MHz. A motor rotated a 15 MHz central frequency transducer to receive 1000 × 1000 × 250 points data. The envelope of the signal was obtained using the Hilbert transform for reconstruction. Then, the JYBL-I solution was used to reduce the HAP component in the bone. The PAM imaging was performed after different immersion times, (i.e., at 0, 5, and 10 mins). In the PAM measurement of the cancellous bone, the imaging area was a cylinder with an 8 mm diameter and an 8 μm/pixel resolution. Results/Discussion: The results showed that the trabecular microstructure could be imaged with a relatively high quality using the PAM technique. With the different extent of HAP degradation by immersion in JYBL-I solution, some trabecular bone disappeared corresponding with PA signals decreased significantly in amplitude. Conclusion: These results indicate that the PA technique has potential application in the characterization of bone microstructure and biochemical components with a high resolution.

The Use Of Computer Assisted Planning To Increase The Predictability Of Intra Oral Welding Technique Of Dental Implants - A Clinical Study

Background: substantial progress has been made in terms of the immediate placement of dental implants after tooth extraction. In cases were the bone is healthy with no atrophy, Periapical lesions, infection and enough bone component is available immediate implant is considered. Recently implant abutment welding was introduced specially for those edentulous patients who need immediate loading and who wanted to go out of the surgery with full load of teeth and a perfect esthetics and function. Materials and Methods: In this prospective randomized controlled study, 8 patients of ASA physical status I and II belonging to age group of 50-60years undergoing dental implants, welding and immediate restorations were randomly allocated into 2 groups of 4 patients each, Group A with intraoral bending of wire and Group B in which wire was pre bent on a STL model before surgery (computer aided) Results: There was no significant difference between stability values measured at different intervals Intra-operative time and bone loss measured in group (B) was significantly higher than that measured in group (A) Conclusion: The use of computer assisted planning to increase the predictability of intra oral welding technique of dental implants saves much time intra operatively and preserves bone from being lost

Applications of type I and II collagen in osteochondral tissue engineering: Respective features and future perspectives

At present, osteoarthritis stands as one of the most prevalent degenerative musculoskeletal diseases globally. The inherent lack of self-healing capacity in articular cartilage presents a considerable obstacle in treating osteoarthritis. Tissue engineering emerged as a promising strategy for the regeneration of osteochondral defects. Collagen, a primary component of bone and cartilage, stands out as a widely utilized natural material in osteochondral tissue engineering. Among various collagen types, Type I and type II collagen are notably prominent in this field. This review initially summarizes the advantageous and disadvantageous properties of type I/II collagen in osteochondral tissue engineering, proceeds to introduce their applications in this context, and concludes with a prospective outlook on the future development of type I/II collagen's applications.

Characterization of biological and mechanical properties of 3D-bioprinted osteochondral plugs

Three-dimensional (3D) bioprinting offers significant potential for the repair of articular cartilage by engineering functional osteochondral tissue. However, progress has been hindered by a lack of printable bioinks that promote the development of bone and chondral tissue while also maintaining sufficient cytocompatibility and mechanical strength. Herein, we designed a biphasic osteochondral plug with distinct chondral and bone regions and developed suitable bioinks for each tissue using photorheology and compression testing. The chondral region consisted of human bone marrow-derived mesenchymal stem cells (hbMSCs) encapsulated in a chondral bioink composed of methacrylated hyaluronic acid and high molecular weight hyaluronic acid. The bone region was 3D bioprinted from an hbMSC-laden methacrylated gelatin (GelMA) bioink and a biodegradable thermoplastic and ceramic lattice that provided mechanical strength. The viability and functionality of hbMSC encapsulated in the bioinks were confirmed through live/dead assays, histology, biochemical assays, and fluorescence microscopy. Over 56 days of culture in a chondrogenic medium, hbMSCs encapsulated in chondral bioink deposited cartilage-like extracellular matrix components, such as type II collagen and glycosaminoglycans. Similarly, cells encapsulated in the bone bioink and cultured in osteogenic medium deposited hydroxyapatite, a key component of bone. These findings provide promising initial results for using 3D-bioprinted plugs to repair osteochondral defects in articular cartilage. &amp;nbsp;

Preparation and Characterization of Hydroxyapatite Using Precursor Extracted from Cockle Shell Waste

Hydroxyapatite (HAP) is a widely used biomaterial due to its excellent bioactivity, biocompatibility, and structural similarity to the mineral component of human bone and teeth. However, the synthesis of HAP typically relies on expensive and non-renewable precursors, which can limit its widespread applications. This study investigates the extraction and purification of HAP from cockle shells, which are a readily available and renewable source of calcium carbonate. The extraction and purification of hydroxyapatite (HAP) from cockle shells, which are rich in calcium carbonate, is a promising method for producing HAP for biomedical applications due to its bioactivity and biocompatibility. This study investigates the use of a calcination process and wet slurry precipitation technique to produce HAP from seashells, focusing on the effect of reaction time of phosphate source (KH2PO4) and calcium oxide (CaO) on HAP production. EDX reported Ca/P ratio of 1.61 for HAP synthesized by chemical precipitation for 2 hours of reaction. Meanwhile, the XRD results indicate that a 4-hour reaction time produces more crystalline HAP than shorter reaction times, highlighting the importance of reaction time in HAP synthesis. This research demonstrates the potential of utilizing seashell waste as a valuable natural resource for applications in healthcare and waste management.

Osteogenic potency of dental stem cell-composite scaffolds in an animal cleft palate model

ObjectiveTo evaluate the osteogenic potency of stem cells isolated from human exfoliated deciduous teeth (SHED) in polycaprolactone with gelatin surface modification (PCL-GE) and poly (lactic-co-glycolic acid)-bioactive glass composite (PLGA-bioactive glass (BG)) scaffolds after implantation in a rat cleft model. MethodsCleft palate-like lesions were induced in Sprague-Dawley rats by extracting the right maxillary first molars and drilling the intact alveolar bone. Rats were then divided into five groups: Control, PCL-GE, PCL-GE-SHED, PLGA-BG, and PLGA-BG-SHED, and received corresponding composite scaffolds with/without SHED at the extraction site. Tissue samples were collected at 2, 3, and 6 months post-implantation (4 rats per group). Gross and histological analyses were conducted to assess osteoid or bone formation. Immunohistochemistry for osteocalcin and human mitochondria was performed to evaluate bone components and human stem cell viability in the tissue. ResultsBone tissue formation was observed in the PCL-GE and PLGA-BG groups compared to the control, where no bone formation occurred. PLGA-BG scaffolds demonstrated greater bone regeneration potential than PCL-GE over 2–6 months. Additionally, scaffolds with SHED accelerated bone formation compared to scaffolds alone. Osteocalcin expression was detected in all rats, and positive immunoreactivity for human mitochondria was observed in the regenerated bone tissue with PCL-GE-SHED and PLGA-BG-SHED. ConclusionPCL-GE and PLGA-BG composite scaffolds effectively repaired and regenerated bone tissue in rat cleft palate defects. Moreover, scaffolds supplemented with SHED exhibited enhanced osteogenic potency. Clinical significancePCL-GE and PLGA-BG scaffolds, augmented with SHED, emerge as promising biomaterial candidates for addressing cleft repair and advancing bone tissue engineering endeavors.

Increased AGE Cross-Linking Reduces the Mechanical Properties of Osteons

The osteon is the primary structural component of bone, contributing significantly to its unique toughness and strength. Despite extensive research on osteonal structure, the properties of osteons have not been fully investigated, particularly within the context of bone fragility diseases like type 2 diabetes mellitus (T2DM). This study aims to isolate osteons from bovine bone, simulate the effects of increased advanced glycation end-products (AGEs) in T2DM through ribosylation, and evaluate the mechanical properties of isolated osteons. Osteons extracted from the posterior section of bovine femur mid-diaphysis were processed to achieve a sub-millimeter scale for microscale imaging. Subsequently, synchrotron radiation micro-computed tomography was employed to precisely localize and isolate the osteon internally. While comparable elastic properties were observed between control and ribosylated osteons, the presence of AGEs led to decreased strain to failure. Young’s modulus was quantified (9.9 ± 4.9 GPa and 8.7 ± 3 GPa, respectively), aligning closely with existing literature. This study presents a novel method for the extraction and isolation of osteons from bone and shows the detrimental effect of AGEs at the osteonal level.

Performance Enhancement of Tricalcium Phosphate Film for Bioelectronics with Bio‐Friendly Supercritical Fluids Desorption Technology

AbstractIn the rapidly advancing field of bioelectronics, searching for materials that combine superior insulating properties with biocompatibility is crucial, especially for implantable electronic devices. Traditional insulators in mature CMOS processes, though effective, lack biocompatibility, necessitating the exploration of alternative materials. This study introduces tricalcium phosphate (Ca3(PO4)2), a primary component of human bones, and teeth, as an insulating layer material for the first time. High‐quality, thickness‐controlled Ca3(PO4)2 films are fabricated using magnetron sputtering, and their electrical insulation, stability, and optical transparency have been thoroughly evaluated. To further optimize the insulation performance of Ca3(PO4)2, particularly against residual impurities, and fabrication‐induced defects, a bio‐friendly low‐temperature supercritical fluid desorption (LTSCF‐Desorption) technique is developed, effectively removing impurities, repairing defects, and improving the interface states. After LTSCF‐Desorption treatment, the leakage current of the Ca3(PO4)2 films is reduced by 30%, along with the enhancements of the films' stability and transmittance. Further material analysis clarified the internal mechanisms behind the improvement of the Ca3(PO4)2 films. Overall, this study not only broadens the application scenarios of Ca3(PO4)2 in bioelectronics but also develops a bio‐friendly supercritical desorption technique, providing a new pathway for optimizing the performance of bioelectronic devices and materials.

Biomechanical validation of novel polyurethane-resin synthetic osteoporotic femoral bones in axial compression, four-point bending and torsion

In addition to human donor bones, bone models made of synthetic materials are the gold standard substitutes for biomechanical testing of osteosyntheses. However, commercially available artificial bone models are not able to adequately reproduce the mechanical properties of human bone, especially not human osteoporotic bone.To overcome this issue, new types of polyurethane-based synthetic osteoporotic bone models have been developed. Its base materials for the cancellous bone portion and for the cortical portion have already been morphologically and mechanically validated against human bone. Thus, the aim of this study was to combine the two validated base materials for the two bone components to produce femur models with real human geometry, one with a hollow intramedullary canal and one with an intramedullary canal filled with synthetic cancellous bone, and mechanically validate them in comparison to fresh frozen human bone.These custom-made synthetic bone models were fabricated from a computer-tomography data set in a 2-step casting process to achieve not only the real geometry but also realistic cortical thicknesses of the femur. The synthetic bones were tested for axial compression, four-point bending in two planes, and torsion and validated against human osteoporotic bone.The results showed that the mechanical properties of the polyurethane-based synthetic bone models with hollow intramedullary canals are in the range of those of the human osteoporotic femur. Both, the femur models with the hollow and spongy-bone-filled intramedullary canal, showed no substantial differences in bending stiffness and axial compression stiffness compared to human osteoporotic bone. Torsional stiffnesses were slightly higher but within the range of human osteoporotic femurs.Concluding, this study shows that the innovative polyurethane-based femur models are comparable to human bones in terms of bending, axial compression, and torsional stiffness.

A Review of Histological Techniques for Differentiating Human Bone from Animal Bone.

The first step in anthropological study is the positive identification of human remains, which can be a challenging undertaking when bones are broken. When bone pieces from different species are mixed together, it can be crucial to distinguish between them in forensic and archaeological contexts. For years, anthropology and archaeology have employed the histomorphological analysis of bones to evaluate species-specific variations. Based on variations in the dimensions and configuration of Haversian systems between the two groups, these techniques have been devised to distinguish between non-human and human bones. All of those techniques concentrate on a very particular kind of bone, zone, and segment. Histomorphometric techniques make the assumption that there are size, form, and quantity variations between non-humans and humans. The structural components of Haversian bones are significant enough to use discriminant function analysis to separate one from the other. This review proposes a comprehensive literature analysis of the various strategies or techniques available for distinguishing human from non-human bones to demonstrate that histomorphological analysis is the most effective method to be used in the case of inadequate or compromised samples.

Developing and Investigating a Nanovibration Intervention for the Prevention/Reversal of Bone Loss Following Spinal Cord Injury.

Osteoporosis disrupts the fine-tuned balance between bone formation and resorption, leading to reductions in bone quantity and quality and ultimately increasing fracture risk. Prevention and treatment of osteoporotic fractures is essential for reductions in mortality, morbidity, and the economic burden, particularly considering the aging global population. Extreme bone loss that mimics time-accelerated osteoporosis develops in the paralyzed limbs following complete spinal cord injury (SCI). In vitro nanoscale vibration (1 kHz, 30 or 90 nm amplitude) has been shown to drive differentiation of mesenchymal stem cells toward osteoblast-like phenotypes, enhancing osteogenesis and inhibiting osteoclastogenesis simultaneously. Here, we develop and characterize a wearable device designed to deliver and monitor continuous nanoamplitude vibration to the hindlimb long bones of rats with complete SCI. We investigate whether a clinically feasible dose of nanovibration (two 2 h/day, 5 days/week for 6 weeks) is effective at reversing the established SCI-induced osteoporosis. Laser interferometry and finite element analysis confirmed transmission of nanovibration into the bone, and microcomputed tomography and serum bone formation and resorption markers assessed effectiveness. The intervention did not reverse SCI-induced osteoporosis. However, serum analysis indicated an elevated concentration of the bone formation marker procollagen type 1 N-terminal propeptide (P1NP) in rats receiving 40 nm amplitude nanovibration, suggesting increased synthesis of type 1 collagen, the major organic component of bone. Therefore, enhanced doses of nanovibrational stimulus may yet prove beneficial in attenuating/reversing osteoporosis, particularly in less severe forms of osteoporosis.

Effect of Physicochemical Surface Properties of Silicon-Substituted Hydroxyapatite on Angiogenesis.

Synthetic hydroxyapatite (HA) is a widely studied bioceramic for bone tissue engineering (BTE) due to its similarity to the mineral component of bone. As bone mineral contains various ionic substitutions that play a crucial role in bone metabolism, the bioactivity of HA can be improved by adding small amounts of physiologically relevant ions into its crystal structure, with silicate-substituted HA (Si-HA) showing particularly promising results. Nevertheless, it remains unclear how distinct material characteristics influence the bioactivity due to the intertwined nature of surface properties. A coculture methodology was optimized and applied for in vitro quantification of the biological response. Initially, HA and Si-HA samples were produced and characterized. To compare the bioactivity of the samples, a method was developed to measure interactions in an increasingly complex environment, first including fibronectin (FN) adsorption and subsequently cell adhesion in mono and coculture using primary human osteoblasts (hOBs) and human dermal microvascular endothelial cells (HDMECs), with and without FN precoating. An experimental set-up was designed to assess to what extent different surface features of the samples contribute to the induced biological response. An 8-nm gold sputter coating was applied to eradicate the electrochemical differences and polishing and abrading was used to reduce the differences in surface topographies. Overall, 1.25 wt% Si-HA exhibited most nanoscale variations in surface potential. In terms of bioactivity, 1.25 wt% Si-HA samples induced the highest osteoblast attachment and vessel formation. Additionally, in vitro vessel formation was established on Si-HA surfaces using a hOB:HDMEC cell ratio of 70:30 and a methodology was established that enabled the assessment of the relative effect of topographical and electrochemical features induced by silicon substitution in the HA lattice on their bioactivity. It was found that the difference in the amount of protein attached to HA and 1.25 wt% Si-HA after 2 h was affected by topographical differences. Conversely, electrochemical differences induced different vessel-like structure formation in coculture with a FN precoating. Without an FN precoating, both topographical and electrochemical differences dictated the differences in angiogenic response. Overall, 1.25 wt% Si-HA surface features appear to induce the most favorable protein adsorption and cell adhesion in mono and coculture with and without FN precoating.

Trabecular Bone Component Assessment under Orthodontic Loads and Movements during Periodontal Breakdown-A Finite Elements Analysis.

This numerical analysis, by employing Tresca and Von Mises failure criteria, assessed the biomechanical behavior of a trabecular bone component subjected to 0.6, 1.2, and 2.4 N orthodontic forces under five movements (intrusion, extrusion, tipping, rotation, and translation) and during a gradual horizontal periodontal breakdown (0-8 mm). Additionally, they assessed the changes produced by bone loss, and the ischemic and resorptive risks. The analysis employed eighty-one models of nine patients in 405 simulations. Both failure criteria showed similar qualitative results, with Tresca being quantitatively higher by 1.09-1.21. No qualitative differences were seen between the three orthodontic loads. Quantitatively, a doubling (1.2 N) and quadrupling (2.4 N) were visible when compared to 0.6 N. Rotation and translation followed by tipping are the most stressful, especially for a reduced periodontium, prone to higher ischemic and resorptive risks. In an intact periodontium, 1.2 N can be safely applied but only in a reduced periodontium for extrusion and intrusion. More than 0.6 N is prone to increasing ischemic and resorptive risks for the other three movements. In an intact periodontium, stress spreads in the entire trabecular structure. In a reduced periodontium, stress concentrates (after a 4 mm loss-marker for the stress change distribution) and increases around the cervical third of the remaining alveolar socket.