Monitoring bone changes due to calcium, magnesium, and phosphorus loss in rat femurs using Quantitative Ultrasound

The Protocol of Ultrasonic Backscatter Measurements of Musculoskeletal Properties

This study aims to introduce the protocol for ultrasonic backscatter measurements of musculoskeletal properties based on a novel ultrasonic backscatter bone diagnostic (UBBD) instrument. Dual-energy X-ray absorptiometry (DXA) can be adopted to measure bone mineral density (BMD) in the hip, spine, legs and the whole body. The muscle and fat mass in the legs and the whole body can be also calculated by DXA body composition analysis. Based on the proposed protocol for backscatter measurements by UBBD, ultrasonic backscatter signals can be measured in vivo, deriving three backscatter parameters [apparent integral backscatter (AIB), backscatter signal peak amplitude (BSPA) and the corresponding arrival time (BSPT)]. AIB may provide important diagnostic information about bone properties. BSPA and BSPT may be important indicators of muscle and fat properties. The standardized backscatter measurement protocol of the UBBD instrument may have the potential to evaluate musculoskeletal characteristics, providing help for promoting the application of the backscatter technique in the clinical diagnosis of musculoskeletal disorders (MSDs), such as osteoporosis and muscular atrophy.

Influence of Low-Intensity Pulsed Ultrasound Parameters on the Bone Mineral Density in Rat Model: A Systematic Review

OBJECTIVE

Bone recovery typically depends on the age of organisms or the prevalence of metabolic disorders such as osteoporosis, which is a metabolic condition characterized by decreased bone strength and bone mineral density (BMD). Therefore, low-intensity pulsed ultrasound (LIPUS), a non-invasive method for osteogenic stimulation, presents promising results. However, heterogeneity in animal study designs is a typical characteristic. Hence, we conducted a systematic review to evaluate the effectiveness of LIPUS in the recovery of experimental bone defects using rat models. We examined the areal and volumetric BMD to identify LIPUS doses to be applied and evaluated the accuracy reported by previous studies.

METHODS

The Virtual Health Library regional portal, PubMed, Embase, EBSCOhost, Scopus and CAPES were reviewed for animal studies that compared fracture treatments based on LIPUS with sham or no treatments using rat models and reported BMD as an outcome. The tool provided by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) and the Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES) checklist were used to assess the bias and quality of such studies.

RESULTS

Of the six studies reviewed, the most frequently used LIPUS dose had an ultrasonic frequency of 1.0 MHz, repetition rate of 0.1 kHz and pulse duration of 2000 μs. An intensity (ISATA) of 30 mW/cm2 was the most preferred for bone recovery. However, the BMD could not solely irrefutably evaluate the effectiveness of LIPUS in bone recovery as the results were discordant with each other. The discrepancies in experimental methodologies, low-quality classifications and high risk of bias in the selected studies, however, did not validate the undertaking of a meta-analysis.

CONCLUSION

On the basis of the BMD results, no sufficient evidence was found to recommend the use of LIPUS for bone recovery in rat models. Thus, this systematic review indicates that the accuracy of such reports must be improved to improve their scientific quality to facilitate a transition of LIPUS applications from pre-clinical research to clinic use.

A novel quantitative ultrasound technique for identifying non-alcoholic steatohepatitis

BACKGROUND AND AIMS

There remains a need to develop a non-invasive, accurate and easy-to-use tool to identify patients with non-alcoholic steatohepatitis (NASH). Successful clinical and preclinical applications demonstrate the ability of quantitative ultrasound (QUS) techniques to improve medical diagnostics. We aimed to develop and validate a diagnostic tool, based on QUS analysis, for identifying NASH.

METHODS

A total of 259 Chinese individuals with biopsy-proven non-alcoholic fatty liver disease (NAFLD) were enrolled in the study. The histological spectrum of NAFLD was classified according to the NASH clinical research network scoring system. Radiofrequency (RF) data, raw data of iLivTouch, was acquired for further QUS analysis. The least absolute shrinkage and selection operator (LASSO) method was used to select the most useful predictive features.

RESULTS

Eighteen candidate RF parameters were reduced to two significant parameters by shrinking the regression coefficients with the LASSO method. We built a novel QUS score based on these two parameters, and this QUS score showed good discriminatory capacity and calibration for identifying NASH both in the training set (area under the ROC curve [AUROC]: 0.798, 95% confidence interval [CI] 0.731-0.865; Hosmer-Lemeshow test, P = .755) and in the validation set (AUROC: 0.816, 95% CI 0.725-0.906; Hosmer-Lemeshow test, P = .397). Subgroup analysis showed that the QUS score performed well in different subgroups.

CONCLUSIONS

The QUS score, which was developed from QUS, provides a novel, non-invasive and practical way for identifying NASH.

Ultrasonic Backscatter Measurements of Human Cortical and Trabecular Bone Densities in a Head-Down Bed-Rest Study

This study aims to investigate the feasibility of quantitative ultrasonic backscatter in evaluating human cortical and trabecular bone densities in vivo based on a head-down-tilt bed rest study, with 36 participants tested through 90 d of bed rest and 180 d of recovery. Backscatter measurements were performed using an ultrasonic backscatter bone diagnostic instrument. Backscatter parameters were calculated with a dynamic signal-of-interest method, which was proposed to ensure the same ultrasonic interrogated volume in cortical and trabecular bones. The backscatter parameters exhibited significant correlations with site-matched bone densities provided by high-resolution peripheral quantitative computed tomography (0.33 < |R| < 0.72, p < 0.05). Some bone densities and backscatter parameters exhibited significant changes after the 90-d bed rest. The proposed method can be used to characterize bone densities, and the portable ultrasonic backscatter bone diagnostic device might be used to non-invasively reveal mean bone loss (across a group of people) after long-term bed rest and microgravity conditions of spaceflight missions.

A Biphasic Osteovascular Biomimetic Scaffold for Rapid and Self-Sustained Endochondral Ossification

Regeneration of large bones remains a challenge in surgery. Recent developmental engineering efforts aim to recapitulate endochondral ossification (EO), a critical step in bone formation. However, this process entails the condensation of mesenchymal stem cells (MSCs) into cartilaginous templates, which requires long-term cultures and is challenging to scale up. Here, a biomimetic scaffold is developed that allows rapid and self-sustained EO without initial hypertrophic chondrogenesis. The design comprises a porous chondroitin sulfate cryogel decorated with whitlockite calcium phosphate nanoparticles, and a soft hydrogel occupying the porous space. This composite scaffold enables human endothelial colony-forming cells (ECFCs) and MSCs to rapidly assemble into osteovascular niches in immunodeficient mice. These niches contain ECFC-lined blood vessels and perivascular MSCs that differentiate into RUNX2+ OSX+ pre-osteoblasts after one week in vivo. Subsequently, multiple ossification centers are formed, leading to de novo bone tissue formation by eight weeks, including mature human OCN+ OPN+ osteoblasts, collagen-rich mineralized extracellular matrix, hydroxyapatite, osteoclast activity, and gradual mechanical competence. The early establishment of blood vessels is essential, and grafts that do not contain ECFCs fail to produce osteovascular niches and ossification centers. The findings suggest a novel bioengineering approach to recapitulate EO in the context of human bone regeneration.

"Variances" and "in-variances" in hierarchical porosity and composition, across femoral tissues from cow, horse, ostrich, emu, pig, rabbit, and frog

It is very well known that bone is a hierarchically organized material produced by bone cells residing in the fluid environments filling (larger) vascular pores and (smaller) lacunar pores. The extracellular space consists of hydroxyapatite crystals, collagen type I molecules, and water with non-collageneous organics. It is less known to which extent the associated quantities (mineral, organic, and water concentrations; vascular, lacunar, and extracellular porosities) vary across species, organs, and ages. We here investigate the aforementioned quantities across femoral shaft tissues from cow, horse, emu, frog, ostrich, pig, and rabbit; by means of light microscopy and dehydration-demineralization tests; thereby revealing interesting invariances: The extracellular volume fractions of organic matter turn out to be similar across all tested non-amphibian tissues; as do the extracellular volume fractions of hydroxyapatite across all tested mammals. Hence, the chemical composition of the femoral extracellular bone matrix is remarkably "invariant" across differently aged mammals; while the water content shows significant variations, as does the partitions of water between the different pore spaces. The latter exhibit strikingly varying morphologies as well. This finding adds to the ample "universal patterns" in the sense of evolutionary developmental biology; and it provides interesting design requirements for the development of novel biomimetic tissue engineering solutions.