Conversion of red bone marrow into yellow – Cause and mechanisms

Humanized In Vivo Bone Tissue Engineering: In Vitro Preculture Conditions Control the Structural, Cellular, and Matrix Composition of Humanized Bone Organs

Bone tissue engineering (BTE) has long sought to elucidate the key factors controlling human/humanized bone formation for regenerative medicine and disease modeling applications, yet with no definitive answers due to the high number and co-dependency of parameters. This study aims to clarify the relative impacts of in vitro biomimetic 'preculture composition' and 'preculture duration' before in vivo implantation as key criteria for the optimization of BTE design. These parameters are directly related to in vitro osteogenic differentiation (OD) and mineralization and are being investigated across different osteoprogenitor-loaded biomaterials, specifically fibrous calcium phosphate-polycaprolactone (CaP-mPCL) scaffolds and gelatin methacryloyl (GelMA) hydrogels. The results show that OD and mineralization levels prior to implantation, enhanced by a mineralization medium supplement to the osteogenic medium (OM), significantly improve ectopic BTE outcomes, regardless of the biomaterial type. Specifically, preculture conditions are pivotal in achieving more faithful mimicry of human bone structure, cellular and extracellular matrix composition and organization, and provide control over bone marrow composition. This work emphasizes the potential of using biomimetic culture compositions, specifically the addition of a mineralization medium as a cost-effective and straightforward approach to enhance BTE outcomes, facilitating rapid development of bone models with superior quality and resemblance to native bone.

Use of two-point and six-point Dixon MRI for fat fraction analysis in the lumbar vertebral bodies and paraspinal muscles in healthy dogs: comparison with magnetic resonance spectroscopy

Introduction

Fatty degeneration of the vertebral bodies and paravertebral muscles is associated with the presence, severity, and prognosis of spinal disease such as intervertebral disc degeneration. Therefore, the fat fraction (FF) of the vertebral bodies and paraspinal muscles has been considered a potential biomarker for assessing the pathophysiology, progression, and treatment response of spinal disease. Magnetic resonance spectroscopy (MRS) is considered the reference standard for fat quantification; however, it has limitations of a long acquisition time and is technically demanding. Chemical shift-encoding water-fat imaging, called the Dixon method, has recently been applied for rapid fat quantification with high spatial resolution. However, the Dixon method has not been validated in veterinary medicine, and we hypothesized that the Dixon method would provide a comparable assessment of the FF to MRS but would be faster and easier to implement in dogs.

Methods

In this prospective study, we assessed the FF of the lumbar vertebral bodies and paravertebral muscles from the first to sixth lumbar vertebrae using MRS, the two-point Dixon method (LAVA-FLEX), and the six-point Dixon method (IDEAL-IQ) and compared these techniques.

Results and discussion

The FFs of vertebral bodies and paravertebral muscles derived from LAVA-FLEX and IDEAL-IQ showed significant correlations and agreement with those obtained with MRS. In particular, the FFs obtained with IDEAL-IQ showed higher correlations and better agreement with those obtained with MRS than those derived by LAVA-FLEX. Both Dixon methods showed excellent intra- and interobserver reproducibility for FF analysis of the vertebral bodies and paraspinal muscles. However, the test-retest repeatability of vertebral body and paraspinal muscle FF analysis was low for all three sequences, especially for the paraspinal muscles. The results of this study showed that LAVA-FLEX and IDEAL-IQ have high reproducibility and that their findings were highly correlated with the FFs of the lumber vertebral bodies and paraspinal muscles determined by MRS in dogs. The FF analysis could be performed much more easily and quickly using LAVA-FLEX and IDEAL-IQ than using MRS. In conclusion, LAVA-FLEX and IDEAL-IQ can be used as routine procedures in spinal magnetic resonance imaging in dogs for FF analysis of the vertebral bodies and paraspinal muscles.

The role of the haematopoietic stem cell niche in development and ageing

Blood production depends on rare haematopoietic stem cells (HSCs) and haematopoietic stem and progenitor cells (HSPCs) that ultimately take up residence in the bone marrow during development. HSPCs and HSCs are subject to extrinsic regulation by the bone marrow microenvironment, or niche. Studying the interactions between HSCs and their niche is critical for improving ex vivo culturing conditions and genetic manipulation of HSCs, which is pivotal for improving autologous HSC therapies and transplantations. Additionally, understanding how the complex molecular network in the bone marrow is altered during ageing is paramount for developing novel therapeutics for ageing-related haematopoietic disorders. HSCs are unique amongst stem and progenitor cell pools in that they engage with multiple physically distinct niches during their ontogeny. HSCs are specified from haemogenic endothelium in the aorta, migrate to the fetal liver and, ultimately, colonize their final niche in the bone marrow. Recent studies employing single-cell transcriptomics and microscopy have identified novel cellular interactions that govern HSC specification and engagement with their niches throughout ontogeny. New lineage-tracing models and microscopy tools have raised questions about the numbers of HSCs specified, as well as the functional consequences of HSCs interacting with each developmental niche. Advances have also been made in understanding how these niches are modified and perturbed during ageing, and the role of these altered interactions in haematopoietic diseases. In this Review, we discuss these new findings and highlight the questions that remain to be explored.

The association of intravenous vs. humeral-intraosseous vascular access with patient outcomes in adult out-of-hospital cardiac arrests

AIM

While intravenous (IV) vascular access for out-of-hospital cardiac arrest (OHCA) resuscitation is standard, humeral-intraosseous (IO) access is commonly used, despite few supporting data. We investigated the association between IV vs. humeral-IO and outcomes.

METHODS

We utilized BC Cardiac Arrest Registry data, including adult OHCA where the first-attempted intra-arrest vascular access route performed by advanced life support (ALS)-trained paramedics was IV or humeral-IO. We fit a propensity-score adjusted model with inverse probability treatment weighting to estimate the association between IV vs. humeral-IO routes and favorable neurological outcomes (CPC 1-2) and survival at hospital discharge. We repeated models within subgroups defined by initial cardiac rhythm.

RESULTS

We included 2,112 cases; the first-attempted route was IV (n = 1,575) or humeral-IO (n = 537). Time intervals from ALS-paramedic on-scene arrival to vascular access (6.6 vs. 6.9 min) and epinephrine administration (9.0 vs. 9.3 min) were similar between IV and IO groups, respectively. Among IV and humeral-IO groups, 98 (6.2%) and 20 (3.7%) had favorable neurological outcomes. Compared to humeral-IO, an IV-first approach was associated with improved hospital-discharge favorable neurological outcomes (AOR 1.7; 95% CI 1.1-2.7) and survival (AOR 1.5; 95% CI 1.0-2.3). Among shockable rhythm cases, an IV-first approach was associated with improved favorable neurological outcomes (AOR 4.2; 95% CI 2.1-8.2), but not among non-shockable rhythm cases (AOR 0.73; 95% CI 0.39-1.4).

CONCLUSION

An IV-first approach, compared to humeral-IO, for intra-arrest resuscitation was associated with an improved odds of favorable neurological outcomes and survival to hospital discharge. This association was seen among an initial shockable rhythm, but not non-shockable rhythm, subgroups.

Using portable X-ray fluorescence elemental analysis to explore porous skeletal lesions: Interplay of sex, age at death, and cause of death

OBJECTIVES

Search for possible associations between bone elemental concentration and the presence of porous skeletal lesions (PSLs), considering the sex, age, and cause of death (COD) of the individuals.

MATERIALS AND METHODS

The sample comprised 107 non-adult individuals (56 females, 51 males) aged 0-20 (x̄ = 13.2, SD = 5.8) from the Coimbra and Lisbon Identified Skeletal Collections. Cribra cranii, orbitalia, humeralis, and femoralis were recorded as present/absent, and elemental concentrations were assessed by portable x-ray fluorescence (pXRF). A multivariate statistical approach was applied.

RESULTS

Well-preserved skeletons with minimal diagenesis showed no sex-related elemental variations or PSL associations. In contrast, age-at-death correlated with elevated Ca, P, Sr, and Pb levels. Cribra cranii increased with age while other cribra declined post-adolescence. Higher concentrations of Fe and lower of S were linked to cribra cranii. Respiratory infections as COD increased the odds of expressing cribra femoralis (OR = 5.25, CI = 1.25-15.14), cribra cranii (OR = 2.91, CI = 0.97-8.69), and cribra orbitalia (OR = 2.76, CI = 1.06-7.24).

DISCUSSION

Feasible pXRF results and low cribra intraobserver error assure replicability. Elevated Ca, P, and Sr in older individuals may relate to skeletal growth, while increased Pb suggests bioaccumulation. Cribra's increase with age reflects different rates of marrow conversion and bone remodeling. Higher Fe and lower S in individuals with cribra cranii possibly reflects poor nutrition, early alcohol use, and sideroblastic anemia, aligning with 19th-20th-century Portugal's living conditions. Respiratory infections increased cribra expression, revealing intricate interplays among inflammation, anemia(s), marrow expansion, and diet. This research highlights a complex scenario and blazes a new path for cribra interpretation.

A Novel Phenotype of Calvarial Thickening and Increased Rates of Premature Calvarial Suture Closure in Children With Chronic Lung Disease

PURPOSE

The purpose of this study was to characterize a novel type of calvarial thickening and provide objective measurements of skull thickness and calvarial suture morphology in patients with bronchopulmonary dysplasia.

METHODS

Infants with severe bronchopulmonary dysplasia who also had undergone computed tomography (CT) scans were identified from the neonatal chronic lung disease program database. Thickness analysis was performed using Materialise Mimics.

RESULTS

The chronic lung disease team treated 319 patients during the study interval of which, 58 patients (18.2%) had head CT available. Twenty-eight (48.3%) were found to have calvarial thickening. The rate of premature suture closure in the study population was 36.2% (21 of 58 patients), with 50.0% of affected cohort having evidence of premature suture closure on the first CT scan. Multivariate logistic regression identified 2 risk factors, requiring invasive ventilation at 6 months of age and fraction of inspired oxygen requirement at 6 months of age. Increased head circumference at birth protected against the development of calvarial thickening.

CONCLUSIONS

We have described a novel subset of patients with chronic lung disease of prematurity who have calvarial thickening with remarkably high rates of premature closure of cranial sutures. The exact etiology of the association is unknown. In this patient population with radiographic evidence of premature suture closure, operative decision should be made after considering unequivocal evidence of elevated intracranial pressure or dysmorphology and balanced against the risk of the procedure.

Apparent diffusion coefficient (ADC) measurements and morphometric evaluation of the cranium in age-matched children with central precocious puberty

OBJECTIVES

Central precocious puberty (CPP) is one of the common reasons for referral to pediatric endocrinology. Magnetic resonance imaging (MRI) is used to rule out intracranial pathologies. However, there is insufficient information in the literature about bone marrow abnormalities on MRI in CPP cases. The aim of this study was to evaluate the apparent diffusion coefficient (ADC) values obtained from bone marrow diffusion weight images (DWI) of cranial bone structures and the status of sphenooccipital synchondrosis (SOS) in CPP.

METHODS

MRI data from 6-to 9-year-old girls with CPP and a healthy control group were evaluated. Anthropometric data, FSH, LH, and oestradiol tests were recorded, and the relationship between SOS status, DWI-ADC values of the clivus, parietal bone, and occipital protuberance were compared.

RESULTS

The study included 146 girls, 79 CPP, and 67 healthy aged 6-9 years (median: 8 (2)). The diagnosis age was 8.30 ± 0.8 years. The ADC values were significantly lower on CPP than normal controls (p=<0.05). In the CPP group, pattern 1 was found at 2 % (n=2), pattern 2 at 3.5 % (n=3), and pattern 3 at 3.5 % (n=3) in clivus sphenooccipital synchondrosis. There was no correlation between the mean parietal, occipital, and clivus ADC values and any variable (p>0.05).

CONCLUSIONS

DWI-MRI ADC analysis can be used as a quantitative radiological marker for early detection of CPP, even before changes in sphenooccipital synchondrosis.

Deep learning-based magnetic resonance imaging of the spine in the diagnosis and physiological evaluation of spinal metastases

Background and objective

Spinal metastasis accounts for 70% of the bone metastases of tumors, so how to diagnose and predict spinal metastasis in time through effective methods is very important for the physiological evaluation of the therapy of patients.

Methods

MRI scans of 941 patients with spinal metastases from the affiliated hospital of Guilin Medical University were collected, analyzed, and preprocessed, and the data were submitted to a deep learning model designed with our convolutional neural network. We also used the Softmax classifier to classify the results and compared them with the actual data to judge the accuracy of our model.

Results

Our research showed that the practical model method could effectively predict spinal metastases. The accuracy was up to 96.45%, which could be used to diagnose the physiological evaluation of spinal metastases.

Conclusion

The model obtained in the final experiment can capture the focal signs of patients with spinal metastases more accurately and can predict the disease in time, which has a good application prospect.

Vertebrae but not femur marrow fat transiently decreases in response to body weight loss in an 18-month randomized control trial

BACKGROUND

Increased levels of bone marrow adipose tissue (BMAT) are negatively associated with skeletal health and hematopoiesis. BMAT is known to increase with age; however, the effect of long-term weight loss on BMAT is still unknown.

OBJECTIVE

In this study, we examined BMAT response to lifestyle-induced weight loss in 138 participants (mean age 48 y; mean body mass index 31 kg/m²), who participated in the CENTRAL-MRI trial.

METHODS

Participants were randomized for dietary intervention of low-fat or low-carb, with or without physical activity. Magnetic resonance imaging (MRI) was used to quantify BMAT and other fat depots at baseline, six and eighteen months of intervention. Blood biomarkers were also measured at the same time points.

RESULTS

At baseline, the L3 vertebrae BMAT is positively associated with age, HDL cholesterol, HbA1c and adiponectin; but not with other fat depots or other metabolic markers tested. Following six months of dietary intervention, the L3 BMAT declined by an average of 3.1 %, followed by a return to baseline after eighteen months (p < 0.001 and p = 0.189 compared to baseline, respectively). The decrease of BMAT during the first six months was associated with a decrease in waist circumference, cholesterol, proximal-femur BMAT, and superficial subcutaneous adipose tissue (SAT), as well as with younger age. Nevertheless, BMAT changes did not correlate with changes in other fat depots.

CONCLUSIONS

We conclude that physiological weight loss can transiently reduce BMAT in adults, and this effect is more prominent in younger adults. Our findings suggest that BMAT storage and dynamics are largely independent of other fat depots or cardio-metabolic risk markers, highlighting its unique functions.

Effects of joint immobilization and treadmill exercise on marrow adipose tissue and trabecular bone after anterior cruciate ligament reconstruction in the rat proximal tibial epiphysis

Marrow adipose tissue (MAT) adversely affects bone metabolism under certain conditions. Although mechanical stress is an important factor in regulating MAT and bone mass, how stress from different rehabilitation protocols after anterior cruciate ligament (ACL) reconstruction affects trabecular bone and MAT is unclear. We aimed to examine the effects of joint immobilization and treadmill exercise on trabecular bone and MAT after ACL reconstruction. Rats received unilateral knee ACL transection and reconstruction surgery. After surgery, rats were reared without intervention, with joint immobilization, or with treadmill exercise (12 m/min, 60 min/day, six days/week), with untreated rats as controls. At two or four weeks after starting experiments, we examined histological changes in trabecular bone and MAT in the proximal tibial epiphysis. After ACL reconstruction, there were no significant changes in trabecular bone area and MAT area at both time points. Joint immobilization after ACL reconstruction resulted in reduced trabecular bone area and MAT accumulation due to adipocyte hyperplasia and hypertrophy within four weeks. Treadmill exercise after ACL reconstruction did not affect any parameters in trabecular bone and MAT. We detected a moderate negative correlation between trabecular bone area and MAT area. Therefore, MAT accumulation induced by joint immobilization may contribute, at least in part, to reducing trabecular bone area. To minimize trabecular bone loss and MAT accumulation, joint immobilization after ACL reconstruction should be minimized. Exercise after ACL reconstruction did not alter trabecular bone and MAT.

Dual-Energy Computed Tomography-Based Quantitative Bone Marrow Imaging in Non-Hematooncological Subjects: Associations with Age, Gender and Other Variables

Background: Our aim is to assess the utility and associations of quantitative bone marrow attenuation (BMA) values measured on clinical dual-energy computed tomography (DECT) exams in non-hematooncologic subjects with skeletal regions, patient age, gender, and other clinical variables. Methods: Our local ethics committee approved this retrospective image data analysis. Between July 2019 and July 2021, 332 eligible patients (mean age, 64 ± 18 years; female, 135) were identified. Inclusion criteria were the availability of a standardized abdominopelvic DECT data set acquired on the same scanner with identical protocol. Eleven regions-of-interest were placed in the T11-L5 vertebral bodies, dorsal iliac crests, and femur necks. Patient age, gender, weight, clinical, habitual variables, inflammation markers, and anemia were documented in all cases. Results: Multi-regression analyses (all, p < 0.05) identified age as the strongest predictor of lumbar BMA (standardized coefficient: β = −0.74), followed by CRP (β = 0.11), LDH (β = 0.11), and gender (β = −0.10). In the lower thoracic spine, age was the strongest predictor (β = −0.58) of BMA, followed by gender (β = −0.09) and LDH (β = 0.12). In femoral bones, age was negatively predictive of BMA (β = −0.12), whereas LDH and anemia were positively predictive (β = 0.16 both). Heart insufficiency significantly decreased (β = 0.12, p = 0.034) a BMA value gradient from higher to lower HU values along the vertebrae T11 and L5, whereas age significantly increased this gradient (β = −0.2, p ≤ 0.001). Conclusions: DECT-based BMA measurements can be obtained from clinical CT exams. BMA values are negatively associated with patient age and influenced by gender, anemia, and inflammatory markers.

Association of hemoglobin levels with bone mineral density for adults over 18 years of age: a cross-sectional study

The overall objective of this study was to determine the association between hemoglobin (HGB) and bone mineral density (BMD) in the lumbar and thoracic spine of adults aged ≥ 18 years. This cross-sectional study utilized the non-institutionalized US population from the National Health and Nutrition Survey (NHANES) as the sample source. A multiple linear regression model was used to assess the relationship between HGB and BMD in the lumbar and thoracic spine, with analysis of subgroups conducted according to sex and race. Smooth curve fitting was performed to explore the potential nonlinear relationship. When nonlinearity was found, we further constructed a weighted two-piecewise linear regression model and used a recursive algorithm to calculate the inflection point. After accounting for relevant confounding variables, HGB was found to be negatively associated with lumbar spine BMD in multiple regression models. However, in the subgroup analyses stratified by sex and race, the relationship between HGB and thoracic spine BMD and lumbar spine BMD was only found in women and other races and races that were not recorded. In Non-Hispanic Asian subjects, the relationship between HGB and BMD in the lumbar spine and thoracic spine showed a U-shaped curve. In addition, the relationship between HGB and BMD in the lumbar spine formed an inverted U-shaped curve among participants in other races and those whose race was not reported. Our study shows that HGB has a non-linear relationship with lumbar and thoracic BMD. Further studies are required to elucidate the mechanisms underlying this association.

Magnetic resonance imaging study of normal cranial bone marrow conversion at high altitude

BACKGROUND

To use conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) to investigate the effects of long-term hypoxia on cranial bone marrow conversion in healthy people at high altitudes.

METHODS

A total of 1,130 individuals were selected from altitudinal areas of 2,000-3,000, 3,100-4,000, and >4,100 m. Each altitude range was divided into 5 age groups: 0-5, 6-14, 15-29, 30-49, and ≥50 years. Firstly, cranial bone marrow typing of the participants in each altitude range was performed on sagittal T1-weighted images (T1WI) according to the average diploe thickness and signal intensity of the normal skull, and the relationship between bone marrow conversion and age was analyzed. Secondly, the apparent diffusion coefficient (ADC) values of the frontal bone, parietal bone, occipital bone, and temporal bone were measured in the DWI post-processing workstation and statistical methods were used to analyze whether different altitudinal gradients and long-term hypoxic environment had any effect on cranial bone marrow conversion.

RESULTS

There was a positive correlation between bone marrow type and age in the healthy populations at all 3 levels of altitude (P<0.05). The average thickness of the cranial diploe also positively correlated with age (P<0.05); in the age ranges of 30-49 and ≥50 years, the ADC values of the occipital and temporal bone marrow positively correlated with increasing altitude (P<0.05).

CONCLUSIONS

The cranial bone marrow of normal people at high altitudes changes from Type I to Type IV with increasing age and under the influence of long-term chronic hypoxia. The bone marrow of the occipital and temporal bones of healthy people aged 30-49 and ≥50 years showed erythromedularization during the process of Type III and IV bone marrow conversion.

Marrow adipose tissue accumulation and dysgenesis of the trabecular bone after anterior cruciate ligament transection and reconstruction in the rat proximal tibial epiphysis

The accumulation of marrow adipose tissue (MAT) is frequently associated with bone loss. Although anterior cruciate ligament (ACL) injury induces bone loss, MAT accumulation after ACL injury has not been evaluated. In addition, no information about changes in MAT after ACL reconstruction is available. In this study, we aimed to examine (1) the effects of ACL transection on the amounts of trabecular bone and MAT present, and (2) whether ACL reconstruction inhibits the changes in the trabecular bone and MAT that are induced by ACL transection. ACL transection alone or with immediate reconstruction was performed on the right knees of rats. Untreated left knees were used as controls. Histomorphological changes in the trabecular bone and MAT in the proximal tibial epiphysis were examined prior to surgery and at one, four, and 12 weeks postsurgery. The trabecular bone area on the untreated side increased in a time-dependent manner. However, after ACL transection, the trabecular bone area did not increase during the experimental period, indicating dysgenesis of the bone (bone loss). Dysgenesis of the trabecular bone after ACL transection was attenuated by ACL reconstruction. MAT accumulation due to adipocyte hyperplasia and hypertrophy had been induced by ACL transection by four weeks postsurgery. This ACL transection-induced MAT accumulation was not prevented by ACL reconstruction. Based on these results, we conclude that (1) dysgenesis of the bone in the proximal tibia following ACL transection is accompanied by MAT accumulation, and (2) ACL reconstruction attenuates dysgenesis of the trabecular bone but cannot prevent MAT accumulation.

A biological approach to adult sex differences in skeletal indicators of childhood stress

OBJECTIVES

In previous work examining the etiology of cribra orbitalia (CO) and porotic hyperostosis (PH) in a contemporary juvenile mortality sample, we noted that males had higher odds of having CO lesions than females. Here, we examine potential reasons for this pattern in greater detail. Four non-mutually exclusive mechanisms could explain the observed sex differences: (1) sex-biased mortality; (2) sexual dimorphism in immune responses; (3) sexual dimorphism in bone turnover; or (4) sexual dimorphism in marrow conversion.

SUBJECTS AND METHODS

The sample consists of postmortem computed tomography scans and autopsy reports, field reports, and limited medical records of 488 individuals from New Mexico (203 females; 285 males) aged between 0.5 and 15 years. We used Kaplan-Meier survival analysis, predicted probabilities, and odds ratios to test each mechanism.

RESULTS

Males do not have lower survival probabilities than females, and we find no indications of sex differences in immune response. Overall, males have a higher probability of having CO or PH lesions than females.

CONCLUSIONS

All results indicate that lesion formation in juveniles is influenced by some combination of sex differences in the pace of red-yellow conversion of the bone marrow and bone turnover. The preponderance of males with CO and PH likely speaks to the potential for heightened osteoblastic activity in males. We find no support for the hypotheses that sex biases in mortality or immune responses impacted lesion frequency in this sample. Sex differences in biological processes experienced by children may affect lesion formation and lesion expression in later life.

Quantitative evaluation of bone marrow fat content and unsaturated fatty index in young male soccer players using proton magnetic resonance spectroscopy (1H-MRS): a preliminary study

Background

Marrow fat exists as a distinct adipose tissue and plays a critical role in affecting both the quantity and quality of bone. However, the effect of soccer training on marrow fat has been rarely reported. This study aims to evaluate and characterize the marrow fat content and composition in different bone areas of soccer players and age-matched healthy subjects using proton magnetic resonance spectroscopy (¹H-MRS).

Methods

Between May 2020 and June 2020, 20 professional soccer players (20.7±0.9 years) and 20 age-matched healthy subjects (21.2±0.8 years) were enrolled in this cross-sectional study. The ¹H-MRS were acquired from the 3^rd lumbar vertebrae, bilateral femoral necks, and distal tibias of all subjects using a single-voxel point-resolved spatially localized spectroscopy (PRESS) sequence. Four soccer players underwent a second magnetic resonance (MR) examination within a 30-minute interval after the initial scan to evaluate test-retest reproducibility. Inter- and intra-observer measurement reliabilities were assessed using 10 randomly selected spectra from the soccer players group. All spectra were processed using the jMRUI software package (http://www.jmrui.eu/). Quantified water and lipid signals were used to calculate fat content (FC) and the unsaturated fatty index (UI).

Results

Compared with healthy subjects, we found that soccer players had a lower FC in L3 and bilateral femoral necks and higher UI in the left femoral neck (P<0.05). All FC and UI values of the bilateral distal tibias showed no significant differences between the two groups (P>0.05). The UI values of the right femoral neck or distal tibia were markedly higher than the left side in both inactive subjects and soccer players (P<0.05, except for the femoral neck in players), and there were notable ΔUI differences in the lower limbs between the soccer players and the healthy subjects (P<0.05).

Conclusions

Soccer practice can be considered a positive sport that contributes to decreasing FC in lumbar vertebrae and femoral necks and increasing the UI in femoral necks. Quantitative MRS provides an ideal modality to predict marrow fat metabolism caused by mechanical stimulation.

Implications of gender-based variabilities in bone mineral density and hemoglobin levels

BACKGROUND

Studies reported that there is a relationship between volumetric bone mineral density (vBMD) and hemoglobin (HGB) in sickle cell anemia, chronic obstructive pulmonary disease, inflammatory bowel disease, and chronic kidney disease, it is not clear whether this association exists in normal populations or different genders. In order to further clarify the relationship between vBMD and HGB, and provide the basis for the diagnosis of related diseases, this study was conducted in the physical examination population.

METHODS

A cross-sectional study was conducted on a health check-up population from Wannan area of China from January to December 2018. The study involved 1238 individuals aged 23 to 85 years. Linear regression analysis and smooth curve were applied to determine the relationship of HGB and vBMD.

RESULTS

The average level of vBMD in the population was 130.11 ± 79.51 mg/cm³, after adjusting for age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), triglycerides (TG), glucose (GLU), high-density lipoprotein (HDL) and low-density lipoprotein (LDL). A U-shape relationship was established between vBMD and HGB, the cut off value of HGB was 130 g/L. After gender stratification, the results showed a U-shaped curve relationship between vBMD and HGB in male group, and a linear relationship between vBMD and HGB in female group. The vBMD decreased with HGB when HGB < 120 g/L, and increased when HGB ≥ 120 g/L in male group.

CONCLUSION

The relationship between vBMD and HGB in the male physical examination population presents a U-shaped curve.

Myeloma and marrow adiposity: Unanswered questions and future directions

Multiple myeloma (MM) is a haematological malignancy characterised by the proliferation and accumulation of terminally differentiated abnormal plasma cells in the bone marrow. Patients suffer from bone pain, factures, anaemia, osteolytic lesions and renal failure. Despite recent advancement in therapy MM remains an incurable disease due to the emergences of drug resistance and frequent relapse. For many decades, research has been heavily focused on understanding the relationship between bone cells such as osteoblast, osteocytes and osteoclasts and the infiltrating tumour cells. However, it is now clear that the tumour-supportive bone microenvironment including cellular and non-cellular components play an important role in driving MM progression and bone disease. One of the most abundant cell types in the bone microenvironment is the bone marrow adipocyte (BMAd). Once thought of as inert space filling cells, they have now been recognised as having specialised functions, signalling in an autocrine, paracrine and endocrine manner to support normal systemic homeostasis. BMAds are both an energy store and a source of secreted adipokines and bioactive substances, MM cells are able to hijack this metabolic machinery to fuel migration, growth and survival. With global obesity on the rise, it has never been more important to further understand the contribution these cells have in both normal and disease settings. The aim of this review is to summarise the large body of emerging evidence supporting the interplay between BMAds and MM cells and to delineate how they fit into the vicious cycle of disease.

The impact of prolonged frozen storage on the preparation quality of bird skins and skeletons in zoological collections

Specimens from zoological collections play a pivotal role in improving scientific knowledge in many natural science disciplines. To guarantee an optimum state of conservation and ensure their usefulness, the preparation process employed is crucial. Skins and skeletons are key elements in vertebrate scientific collections and, ideally, are prepared from recently deceased animals; however, specimens are often stored in a frozen state for a long time (years) prior to preparation. Whether the duration of this frozen state has a deleterious effect on preparation quality has rarely been studied. The main objective of this study was thus to contribute towards research into zoological preparation by testing to see whether prolonged frozen storage hinders the preparation of bird skins and skeletons. We used the common buzzard (Buteo buteo) and the barn owl (Tyto alba) as biological models. Our results showed that long-term frozen storage led to weight loss, bone marrow acidification and solidification, and hampered skin preparation. The necropsy affected weight loss and decreased the skin tear resistance, probably due to tissue dehydration. Thus, prolonged frozen storage appears to have a harmful effect on the preparation quality of vertebrate specimens. Since frozen storage could ultimately have an impact on the conservation and scientific use of museum specimens, practices should be implemented to minimise the amount of time specimens are frozen or to mitigate any detrimental effects. More importance should be attached to research on zoological preparation since it is fundamental for optimising the quality, conservation status, and value of museum collections.

Variation of the apparent diffusion coefficient of skull bone marrow by age group, pubertal status, and gender in a pediatric population

BACKGROUND

Bone marrow composition varies with stage of development.

PURPOSE

To assess differences in apparent diffusion coefficient (ADC) derived from clivus bone marrow in healthy children by age, pubertal status, and gender as a benchmark when monitoring local and systemic treatment-induced effects.

MATERIAL AND METHODS

Non-oncological pediatric patients (30 pre-pubertal [15 girls, 15 boys] and 30 post-pubertal [15 girls, 15 boys]) with previous normal magnetic resonance imaging (MRI) of the brain including diffusion-weighted magnetic resonance imaging (DW-MRI; 1.5-T Philips Achieva-Ingenia, b-values 0 and 1000s/mm2) were studied. A 4-6 mm diameter region of interest (ROI), drawn within the clivus on two or three DW-MRI slices, yielded mean and centile ADC values. Pubertal status was recognized from imaging appearances of the pituitary gland and from fusion of the spheno-occipital synchondrosis. Correlations between ADC and age were assessed (Pearson's coefficient). Mann-Whitney U tests compared ADC by age, pubertal status, and gender.

RESULTS

Age and ADC were significantly negatively correlated (median ADC r=-0.48, mean ADC r=-0.42, P=0.0001 and 0.0008, respectively) which held true when divided by gender. Mean and median ADC differed significantly before and after puberty for the whole population (P=0.0001 and 0.0001, respectively). There was a left shift of the ADC histogram after puberty with significant differences in centile values. ADC differences before and after puberty remained when divided by gender (girls: P=0.04 and 0.009, respectively; boys: P=0.005 and 0.0002, respectively).

CONCLUSION

ADC of clivus bone marrow correlates with age in children. ADC decreases significantly after puberty, likely due to replacement of hypercellular marrow with fat. There are no gender-related differences in clivus bone-marrow ADC before or after puberty.

Cribra orbitalia and porotic hyperostosis are associated with respiratory infections in a contemporary mortality sample from New Mexico

OBJECTIVES

Cribra orbitalia (CO) and porotic hyperostosis (PH) are porous cranial lesions (PCLs) classically associated with iron-deficiency anemia in bioarchaeological contexts. However, recent studies indicate a need to reassess the interpretation of PCLs. This study addresses the potential health correlates of PCLs in a contemporary sample by examining relationships between the known cause of death (COD) and PCL presence/absence.

METHODS

This study includes a sample of 461 juvenile individuals (6 months to 15 years of age) who underwent examination at the University of New Mexico's Office of the Medical Investigator between 2011 and 2019. The information available for each individual includes their sex, age at death, and their COD and manner of death.

RESULTS

Odds ratio of having CO (OR = 3.92, p < .01) or PH (OR = 2.86, p = .02) lesions are increased in individuals with respiratory infections. Individuals with heart conditions have increased odds of having CO (OR = 3.52, p = .03) lesions, but not PH.

CONCLUSION

Individuals with respiratory infection are more likely to have CO and/or PH. CO appears to have a greater range of health correlates than PH does, as indicated by the heart condition results. However, individuals with congenital heart defects are at higher risk for respiratory infections, so bony alterations in cases of heart conditions may be due to respiratory illness. Since respiratory infection remains a leading cause of mortality today, CO and PH in bioarchaeological contexts should be considered as potential indicators of respiratory infections in the past.

Hyperplasia and accelerated hypertrophy of marrow adipocytes with knee immobilization were sustained despite remobilization

Skeletal disuse can cause an accumulation of bone marrow adipose tissue (MAT) characterized by a combination of marrow adipocyte hyperplasia and/or hypertrophy. The malleability of MAT accumulation and of the hyperplasia and hypertrophy upon remobilization is unknown. In this study, we showed extensive hyperplasia and accelerated hypertrophy of bone marrow adipocytes in the proximal tibia epiphysis of rat knees immobilized for durations between 1 and 32 wk. Similar histomorphometric measures of adipocytes carried out in unoperated controls allowed distinguishing the effects of immobilization from the effects of aging. Although both knee immobilization and aging led to adipocyte hypertrophy, adipocyte hyperplasia was the hallmark signature effect of immobilization on MAT. Both bone marrow adipocyte hyperplasia and hypertrophy were sustained despite knee remobilization for durations up to four times the duration of immobilization. These results suggest that adipocyte hyperplasia is the predominant mechanism explaining MAT accumulation in skeletal disuse. In this model, the changes were unremitting for the investigated time points. Investigating the cellular and molecular mechanisms of marrow adipocyte mechanoregulation will be important to better understand how adipocytes adapt to changes in mechanical environments.NEW & NOTEWORTHY This longitudinal study elucidates the response of marrow adipose tissue adipocytes in weight-bearing joints to changes in different mechanical environments, and we provide insight on the malleability of the changes over time. In a rat animal model, knee immobilization induced hyperplasia and accelerated the age-dependent hypertrophy of adipocytes. Changes in adipocyte number and size were sustained despite unassisted remobilization. Multimodal distributions of cell size were characteristic of bone marrow adipocytes.

Hemoglobin levels and low bone mineral density in non-anemic older adults: Secondary analysis of the Korean National Health and Nutrition Examination Survey

BACKGROUND

Although, previous studies have reported a positive association between hemoglobin levels and bone mineral density (BMD), the majority of the studies were limited in patients with chronic hypoxemic conditions and findings concerning the association among non-anemic populations are inconclusive. We aimed to examine the association between hemoglobin levels and BMD in non-anemic healthy adults.

METHODS

This cross-sectional study included 3626 non-anemic men and women aged ≥ 60 years who participated in the Korean National Health and Nutrition Examination Survey (KNHANES). The BMD of the lumbar spine and both femurs was measured by dual-energy X-ray absorptiometry (DXA). Participants with T-score for BMD < -1.0 SD were defined as having low BMD. The odds ratios (ORs) and 95% confidence intervals (CIs) for low BMD were calculated using multiple logistic regression analyses across sex-specific hemoglobin quartiles.

RESULTS

The prevalence of low BMD gradually decreased in accordance with hemoglobin quartiles in both sexes. Compared with the group in the lowest quartile, the OR (95% CI) for low BMD in the lumbar spine was 0.78 (0.54-0.93) for men and 0.67 (0.50-0.93) for women after adjusting for age, BMI, tobacco smoking, alcohol intake, physical activity, walking difficulty, household income, total calorie intake, calcium intake, iron intake, 25(OH)D, alkaline phosphatase, and parathyroid hormone levels. However, these positive associations were not found in femur after adjusting for the same co-variables.

CONCLUSIONS

Hemoglobin levels were inversely associated with low BMD in lumbar spine among non-anemic adults.

Porcine reproductive and respiratory syndrome virus infection of bone marrow: Lesions and pathogenesis

Red bone marrow is physiologically unique in that it is both the major hematopoietic organ and a primary lymphoid organ. Porcine reproductive and respiratory syndrome virus (PRRSV) affects normal bone marrow functions. The cumulative effect of PRRSV infection is acute bone marrow failure, i.e., hypoplasia characterized by the absence of normal myeloid and erythroid precursors and increased red bone marrow M:E ratios. The measurable clinical consequence of PRRSV infection on normal red bone marrow functions is a reduction in the number of cells emigrating to the peripheral blood resulting in leucopenia, anemia, and thrombocytopenia. These observations may be explained by the fact that bone marrow-derived mononuclear cells, i.e., imDCs, mDCs, monocytes, macrophages, and myeloid precursor cells are susceptible to PRRSV. Apoptosis in bone marrow-derived cells occurs both as a direct consequence of infection and indirectly via a bystander effect. Immunologically, PRRSV-susceptible mononuclear cells are the first line of defense against microbial infection and responsible for antigen recognition, processing, and presentation to T and B cells; a critical step in the initiation and development of an effective adaptive immune. Thus, impairment of normal immune function renders the host less able to resist and/or eliminate secondary infectious agents and partially explains the synergy between PRRSV and bacterial and viral co-infections.

Bone marrow adiposity and multiple myeloma

Multiple Myeloma (MM) is an incurable haematological malignancy and is the second most common blood cancer in adults; it is caused by the clonal expansion of abnormal plasma cells within the bone marrow and characterized by osteolytic bone lesions, bone pain, renal disease, and immunodeficiency. MM cells infiltrate the bone marrow where they hijack the microenvironment to sustain growth and survival. The contribution to this process by resident bone cells is well defined. However, the role of bone marrow adipocytes is less clear. As one of the most abundant cell types in the bone marrow these cells are surprisingly understudied. However, in the last few decades they have been recognised as having endocrine function. Adipocytes are metabolically active cells that secrete adipokines, growth factors, and inflammatory mediators, they influence the behaviour and function of neighbouring cells; and have the potential to dysregulate normal bone homeostasis. This review discusses how adipocytes contribute to the metastatic niche in multiple myeloma and cancers that metastasise to the bone and how these new discoveries may contribute to further understanding the mechanisms driving the devastating bone disease associated with MM.

Physiological uptake of 18F-FDG in the vertebral bone marrow in healthy adults on PET/CT imaging

BACKGROUND

18F-fluorodeoxyglucose *Equal contributors. positron emission tomography/computed tomography (18F-FDG PET/CT) has proven to be a valuable imaging modality for the assessment of bone marrow condition.

PURPOSE

To investigate the physiological uptake of 18F-FDG in the vertebral bone marrow in healthy adults on PET/CT imaging, and correlate the appearance with clinical factors including gender, body mass index, and age.

MATERIAL AND METHODS

A total of 64 healthy individuals underwent PET/CT scan, and for each vertebral body, the mean and maximum standardized uptake value (SUVmean and SUVmax) were determined in the central slice of vertebral body on the transversal fused PET/CT image. For each individual, the FDG uptake of the four regions was obtained by averaging the SUVmean and SUVmax of the vertebrae in individual regions.

RESULTS

The FDG uptake from thoracic to sacral vertebrae showed an upward trend first, then a downward trend, while that of cervical vertebrae was relatively stable. The SUVmax and SUVmean values of bone marrow in the old group (age ≥ 50 years) were significantly lower than those in the young group (age < 50 years) in all regions of the spine ( P < 0.05). FDG uptake of the whole spine showed significant negative correlation with age, and the strongest correlation was observed in lumbar spine (SUVmean: r = -0.364, P < 0.05; SUVmax: r = -0.344, P < 0.05).

CONCLUSION

FDG uptake showed a tendency to increase first then decrease from thoracic to sacral vertebrae while the tendency was not obvious in cervical vertebrae. In addition, the glycolytic metabolism of all the four regions decreased with advancing age.

Relative skeletal distribution of proliferating marrow in the adult dog determined using 3'-deoxy-3'-[18 F]fluorothymidine

3'-deoxy-3'-[¹⁸ F]fluorothymidine (¹⁸ FLT) is a radiopharmaceutical tracer used with positron emission tomography (PET), often in combination with computed tomography (CT), to image DNA synthesis, and thus, cellular proliferation. Characteristic accumulation of the tracer within haematopoietic bone marrow provides a noninvasive means to assess marrow activity and distribution throughout the living animal. The present study utilizes three-dimensional analysis of ¹⁸ FLT-PET/CT scans to quantify the relative skeletal distribution of active marrow by anatomic site in the dog. Scans were performed on six healthy, adult (3-6 years of age), mixed-breed dogs using a commercially available PET/CT scanner consisting of a 64-slice helical CT scanner combined with an integrated four ring, high-resolution LSO PET scanner. Regions of interest encompassing 11 separate skeletal regions (skull, cervical vertebral column, thoracic vertebral column, lumbar vertebral column, sacrum, ribs, sternum, scapulae, proximal humeri, ossa coxarum, and proximal femora) were manually drawn based on CT images and thresholded by standardized uptake value to delineate bone marrow activity. Activity within each skeletal region was then divided by the total skeletal activity to derive the per cent of overall marrow activity within an individual site. The majority of proliferative marrow was located within the vertebral column. Of the sites traditionally accessed clinically for marrow sampling, the proximal humerus contained the largest percentage, followed by the ossa coxarum, proximal femur, and sternum, respectively. This information may be used to guide selection of traditional marrow sampling sites as well as inform efforts to spare important sites of haematopoiesis in radiation therapy planning.

Favorable Outcome of Post-Transplantation Cyclophosphamide Haploidentical Peripheral Blood Stem Cell Transplantation with Targeted Busulfan-Based Myeloablative Conditioning Using Intensive Pharmacokinetic Monitoring in Pediatric Patients

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with post-transplantation cyclophosphamide (PTCy) was performed previously in adults using a nonmyeloablative conditioning regimen and bone marrow as a graft source. In an effort to reduce relapse rates, myeloablative conditioning regimens with higher intensities are now used. We used an intensive daily pharmacokinetic monitoring method for busulfan dosing in children for effective myeloablation and to reduce toxicity. Here, we report the retrospective results of 34 patients (median age 11.1 years) who underwent haplo-HSCT with PTCy using a targeted busulfan-based myeloablative conditioning regimen and peripheral blood as a stem cell source. The donor-type neutrophil engraftment rate was 97.1%, and the cumulative incidence rates of grade II to IV and grade III to IV acute and extensive chronic graft-versus-host disease were 38.2%, 5.9%, and 9.1%, respectively. The overall survival and event-free survival rates, and treatment-related mortality were 85.0%, 79.4%, and 2.9%, respectively. Based on the subgroup analysis of patients with malignancies (n = 23), the relapse incidence rate was 21.7%. Haplo-HSCT using PTCy with targeted busulfan-based myeloablative conditioning and peripheral blood as a stem cell source was a safe and promising therapeutic option for children.

Arrested pneumatization of the sphenoid sinus mimicking skull base tumours: MRI prevalence in children with haematologic diseases

Objective: Arrested pneumatization of the sphenoid sinus is a developmental anatomic variation but may be confused with serious diseases of the skull base. The purpose of this study was to investigate the prevalence of arrested pneumatization of the sphenoid sinus in paediatric patients with haemotologic diseases like sickle cell anaemia, thalassemia and leukemia. Materials and Methods: One hundred and eight paediatric patients (43 girls, 65 boys; age range: 4-18 years; median age: 13 years) with haemotologic diseases who underwent at least one magnetic resonance imaging of the head and neck between 2010 and 2017 in a single institution were included. Magnetic resonance imaging studies were retrospectively reviewed. Well-defined and fat-containing non-expansile lesions located at the sphenoid sinus region were diagnosed as arrested pneumatization of the sphenoid sinus. Medical diagnoses, lesion sizes, age and sex of the patients were recorded. Results: Five (4.6%) of 108 patients demonstrated arrested pneumatization of the sphenoid sinus (3 girls, 2 boys; age range: 9-18 years; median age: 14 years). One (1.2%) of 83 patients with acute leukemia, 2 (15%) of 13 patients with sickle cell anaemia and 2 of 12 (17%) patients with thalassemia demonstrated arrested pneumatization of the sphenoid sinus. No statistical correlation was found between arrested pneumatization of the sphenoid sinus and possible risk factors like patient age and sex. Conclusions: Patients with haemoglobinopathies like sickle cell anaemia and thalassemia involving red-blood-cells had higher prevalence of arrested pneumatization of the sphenoid sinus than patients with leukemia which involves the white-blood-cells. This supported the suggestion that regional blood-flow disorders induce arrested pneumatization of the sphenoid sinus. Correct diagnosis prevents invasive procedures like biopsy and surgery.

The effects of knee immobilization on marrow adipocyte hyperplasia and hypertrophy at the proximal rat tibia epiphysis

Marrow adipose deposition is observed during aging and in association with extended periods of immobility. The objective of this study was to determine the contribution of adipocyte hypertrophy and hyperplasia to bone marrow fat deposition induced by immobilization of the rat knee joint for 2, 4, 16 or 32 weeks. Histomorphometric analyses compared immobilized to sham-operated proximal tibia from age and gender matched rats to assess the contribution of aging and duration of immobilization on the number and size of marrow adipocytes. Results indicated that marrow adipose tissue increased with the duration of immobilization and was significant larger at 16 weeks compared to the sham-operated group (0.09956±0.13276mm² vs 0.01990±0.01100mm², p=0.047). The marrow adipose tissue was characterized by hyperplasia of adipocytes with a smaller average size after 2 and 4 weeks of immobilization (at 2 weeks hyperplasia: 68.86±33.62 vs 43.57±24.47 adipocytes/mm², p=0.048; at 4 weeks hypotrophy: 0.00036±0.00019 vs 0.00046±0.00023mm², p=0.027), and by adipocyte hypertrophy after 16 weeks of immobilization (0.00083±0.00049 vs 0.00046±0.00028mm², p=0.027) compared to sham-operated. Both immobilized and sham-operated groups showed marrow adipose conversion with age; immobilized (p=0.008; sham: p=0.003). Overall, fat deposition in the bone marrow of the proximal rat tibia epiphysis and induced by knee joint immobilization was characterized by hyperplasia of small adipocytes in the early phase and by adipocyte hypertrophy in the later phase. Mediators of marrow fat deposition after immobilization and preventive countermeasures need to be investigated.

Inhibition of Adipogenesis Is Involved in the Protective Effects of 1,25-Dihydroxy Vitamin D3 on the Radiation-Injured Bone Marrow Microenvironment in Mice

To explore the protective effects of 1,25-dihydroxy vitamin D3 (1,25-(OH)₂D₃) on the bone marrow microenvironment in mice after irradiation and the underlying molecular mechanisms, a total of 150 7-wk-old male BALB/c mice were randomly divided into a normal group, an irradiation (IR) group and an irradiation+1,25-(OH)₂D₃ (IR+VD3) group. The mice in the IR+VD3 group were treated with 6.0 Gy ⁶⁰Coγ rays, and 1,25-(OH)₂D₃ (dissolved in DMSO, 2.5 μg/kg) was administered once per day from 2 d before to 8 d after irradiation. Mice in the IR group were treated with the same dose of γ rays and an equal volume of DMSO. Subsequently, the body weights and the numbers of peripheral white blood cells (WBCs) were measured. Histological analysis of femur bone marrow was conducted to determine the proportion of adipose area as well. Finally, the expression of peroxisome proliferator-activated receptor-gamma (PPARγ) in bone marrow was detected by immunohistochemistry. After irradiation, the percentage of adipose area in the bone marrow was significantly increased, and the WBC number and body weight were markedly reduced. Compared with irradiation alone, the co-administration of 1,25-(OH)₂D₃ with irradiation markedly attenuated radiation-induced adipogenesis in bone marrow, resulted in fewer bone marrow stromal cells expressing PPARγ and enhanced the recovery of body weight and WBCs. These results indicate that 1,25-(OH)₂D₃ could accelerate the recovery of body weight and WBCs in irradiated mice and protect the bone marrow by inhibiting radiation-induced adipogenesis via the down-regulation of PPARγ expression.

Enhancing Mass Lesion of the Sphenoid: Atypical Presentation of Ongoing Pneumatization

Sinus pneumatization is a complex variable process that begins in early life and continues for many years. We present a case of a 6-year-old boy with progressive headaches and neurologic symptoms suggestive of intracranial pathology. The presence of enhancing tissue within the sphenoid sinus created a diagnostic dilemma which leads to a transsphenoidal biopsy. Knowledge of imaging characteristics associated with incomplete pneumatization can help differentiate it from more ominous skull base pathology and prevent unnecessary testing. We describe four-year imaging follow-up in a patient with incomplete pneumatization of the sphenoid sinus presenting as an enhancing mass lesion with subsequent follow-up imaging demonstrating gradual regression and increased aeration of the sphenoid sinus.

Bone: A Fertile Soil for Cancer Metastasis

Bone is one of the most common and most dangerous sites for metastatic growth across cancer types, and bone metastasis remains incurable. Unfortunately, the processes by which cancers preferentially metastasize to bone are still not well understood. In this review, we summarize the morphological features, physical properties, and cell signaling events that make bone a unique site for metastasis and bone remodeling. The signaling crosstalk between the tumor cells and bone cells begins a vicious cycle - a self-sustaining feedback loop between the tumor cells and the bone microenvironment composed of osteoclasts, osteoblasts, other bone marrow cells, bone matrix, and vasculature to support both tumor growth and bone destruction. Through this crosstalk, bone provides a fertile microenvironment that can harbor dormant tumor cells, sometimes for long periods, and support their growth by releasing cytokines as the bone matrix is destroyed, similar to providing nutrients for a seed to germinate in soil. However, few models exist to study the late stages of bone colonization by metastatic tumor cells. We describe some of the current methodologies used to study bone metastasis, highlighting the limitations of these methods and alternative future strategies to be used to study bone metastasis. While <i>in vivo</i> animal and patient studies may provide the gold standard for studying metastasis, <i>ex vivo</i> models can be used as an alternative to enable more controlled experiments designed to study the late stages of bone metastasis.

The CT Prevalence of Arrested Pneumatization of the Sphenoid Sinus in Patients with Sickle Cell Disease

BACKGROUND AND PURPOSE

Arrested sphenoid pneumatization is an incidental radiologic finding on CT and MR imaging that may be confused with more aggressive pathologic conditions. No definite etiology for arrested sphenoid pneumatization has been established, though changes in regional blood flow during childhood, as is seen with sickle cell disease, have been proposed. The purpose of our study was to compare the prevalence of arrested pneumatization of the sphenoid sinus in patients with and without sickle cell disease.

MATERIALS AND METHODS

We retrospectively identified 146 patients with sickle cell disease who had undergone CT scans of the skull base between January 1990 and May 2015. We identified 292 control patients without sickle cell disease matched for age and sex in a 1:2 ratio. We tabulated the prevalence of arrested pneumatization as well as the location and size of the lesions. We used the Fisher exact test to correlate sickle cell disease with arrested pneumatization of the sphenoid sinus and the t test to correlate sickle cell disease with lesion size.

RESULTS

Of the 146 patients with sickle cell disease, 14 (9.6%) had arrested pneumatization of the sphenoid sinus. In the 292 control patients, 6 (2.1%) had arrested pneumatization. Patients with sickle cell disease had a statistically significant higher rate of arrested pneumatization compared with patients without sickle cell disease (P < .001). There was no statistically significant correlation between lesion size and diagnosis of sickle cell disease.

CONCLUSIONS

Patients with sickle cell disease have a greater prevalence of arrested pneumatization of the sphenoid sinus than patients without sickle cell disease. This supports the theory that either regional blood flow anomalies or increased serum erythropoietin causes arrested sinus pneumatization.

Arrested pneumatization of the sphenoid sinus mimicking intraosseous lesions of the skull base

Arrested pneumatization of the sphenoid sinus is a developmental variant that is not always well recognized and is often confused with other pathologies associated with the skull base. This report describes the case of a patient referred for cone-beam computed tomography (CBCT) imaging for dental implant therapy. CBCT demonstrated a well-defined incidental lesion in the left sphenoid sinus with soft tissue-like density and sclerotic borders with internal curvilinear opacifications. The differential diagnoses included intraosseous lipoma, arrested pneumatization of the sphenoid sinus, chondrosarcoma, chondroid chordoma, and ossifying fibroma. The radiographic diagnosis of arrested pneumatization was based on the location of the lesion, its well-defined nature, the presence of internal opacifications, and lack of expansion. Gray-scale CBCT imaging of the area demonstrated values similar to fatty tissue. This case highlighted the fact that benign developmental variants associated with the skull base share similar radiographic features with more serious pathological entities.

Extending human hematopoietic stem cell survival in vitro with adipocytes

Human hematopoietic stem cells (hHSCs) cannot be maintained in vitro for extended time periods because they rapidly differentiate or die. To extend in vitro culture time, researchers have made attempts to use human mesenchymal stem cells (hMSCs) to create feeder layers that mimic the stem cell niche. We have conducted an array of experiments including adipocytes in these feeder layers that inhibit hHSC differentiation and by that prolong stem cell survival in vitro. The amount of CD34⁺ cells was quantified using flow cytometry. In a first experiment, feeder layers of undifferentiated hMSCs were compared with feeder layers differentiated toward osteoblasts or adipocytes using minimal medium, showing the highest survival rate where adipocytes were included. The same conclusion was drawn in a second experiment in comparing hMSCs with adipogenic feeder cells, using a culture medium supplemented with a cocktail of hHSC growth factors. In a third experiment, it was shown that direct cell–cell contact is necessary for the supportive effect of the feeder layers. In a fourth and fifth experiment the amount of adipocytes in the feeder layers were varied, and in all experiments a higher amount of adipocytes in the feeder layers showed a less rapid decay of CD34⁺ cells at later time points. We therefore concluded that adipocytes assist in suppressing hHSC differentiation and aid in prolonging their survival in vitro.

3 Tesla (1) H MR spectroscopy of hip bone marrow in a healthy population, assessment of normal fat content values and influence of age and sex

PURPOSE

To evaluate in a healthy population normal spectroscopic fat content (FC) values of the hip bone marrow and to assess the influence of age and sex on bone marrow conversion.

MATERIALS AND METHODS

Eighty volunteers (40 men; 40 women; ages: 20-60 years; divided into four consecutive groups) underwent acetabulum, femoral head, femoral neck, greater trochanter, and diaphysis localized (1) H MR spectroscopy. FC values of each anatomical site were obtained according to the following formula: Fat content = CH2 /(CH2  + Water)*100. To assess bone marrow conversion, a spectroscopic conversion index (SCI) was calculated as FC neck/FC greater trochanter.

RESULTS

FC values showed a gradient as follows: greater trochanter > femoral head > femoral neck > diaphysis > acetabulum in every age group both in men and in women. SCI increased with age both in men and women, showing lower values in women for every age group.

CONCLUSION

We obtained normal spectroscopic FC values from different areas of the hip, according to age and sex. These values may be used as reference values to evaluate, by the means of (1) H MR spectroscopy, pathological conditions affecting hip bone marrow.

Whole-body biodistribution of 3'-deoxy-3'-[(18) f]fluorothymidine ((18) FLT) in healthy adult cats

Positron emission tomography/computed tomography (PET/CT) utilizing 3'-deoxy-3'-[(18) F]fluorothymidine ((18) FLT), a proliferation tracer, has been found to be a useful tool for characterizing neoplastic diseases and bone marrow function in humans. As PET and PET/CT imaging become increasingly available in veterinary medicine, knowledge of radiopharmaceutical biodistribution in veterinary species is needed for lesion interpretation in the clinical setting. The purpose of this study was to describe the normal biodistribution of (18) FLT in adult domestic cats. Imaging of six healthy young adult castrated male cats was performed using a commercially available PET/CT scanner consisting of a 64-slice helical CT scanner with an integrated whole-body, high-resolution lutetium oxy-orthosilicate (LSO) PET scanner. Cats were sedated and injected intravenously with 108.60 ± 2.09 (mean ± SD) MBq of (18) FLT (greater than 99% radiochemical purity by high-performance liquid chromatography). Imaging was performed in sternal recumbency under general anesthesia. Static images utilizing multiple bed positions were acquired 80.83 ± 7.52 (mean ± SD) minutes post-injection. Regions of interest were manually drawn over major parenchymal organs and selected areas of bone marrow and increased tracer uptake. Standardized uptake values were calculated. Notable areas of uptake included hematopoietic bone marrow, intestinal tract, and the urinary and hepatobiliary systems. No appreciable uptake was observed within brain, lung, myocardium, spleen, or skeletal muscle. Findings from this study can be used as baseline data for future studies of diseases in cats.

Subcutaneous tissue response and osteogenic performance of calcium phosphate nanoparticle-enriched hydrogels in the tibial medullary cavity of guinea pigs

In the current study, oligo(poly(ethylene glycol) fumarate) (OPF)-based hydrogels were tested for the first time as injectable bone substitute materials. The primary feature of the material design was the incorporation of calcium phosphate (CaP) nanoparticles within the polymeric matrix in order to compare the soft tissue response and bone-forming capacity of plain OPF hydrogels with CaP-enriched OPF hydrogel composites. To that end, pre-set scaffolds were implanted subcutaneously, whereas flowable polymeric precursor solutions were injected in a tibial ablation model in guinea pigs. After 8 weeks of implantation, histological and histomorphometrical evaluation of the subcutaneous scaffolds confirmed the biocompatibility of both types of hydrogels. Nevertheless, OPF hydrogels presented a loose structure, massive cellular infiltration and extensive material degradation compared to OPF-CaP hydrogels that were more compact. Microcomputed tomography and histological and histomorphometrical analyses showed comparable amounts of new trabecular bone in all tibias and some material remnants in the medial and distal regions. Particularly, highly calcified areas were observed in the distal region of OPF-CaP-treated tibias, which indicate a heterogeneous distribution of the mineral phase throughout the hydrogel matrix. This phenomenon can be attributed to either hindered gelation under highly perfused in vivo conditions or a faster degradation rate of the polymeric hydrogel matrix compared to the nanostructured mineral phase, resulting in loss of entrapment of the CaP nanoparticles and subsequent sedimentation.