Circulating Osteoprogenitor Cells Have a Mixed Immune and Mesenchymal Progenitor Function in Humans

BACKGROUND

Circulating osteoprogenitors (COP) are a population of cells in the peripheral circulation that possess functional and phenotypical characteristics of multipotent stromal cells (MSCs). This population has a solid potential to become an abundant, accessible, and replenishable source of MSCs with multiple potential clinical applications. However, a comprehensive functional characterization of COP cells is still required to test and fully develop their use in clinical settings.

METHODS

This study characterized COP cells by comparing them to bone marrow-derived MSCs (BM-MSCs) and adipose-derived MSCs (ASCs) through detailed transcriptomic and proteomic analyses.

RESULTS

We demonstrate that COP cells have a distinct gene and protein expression pattern with a significantly stronger immune footprint, likely owing to their hematopoietic lineage. In addition, regarding progenitor cell differentiation and proliferation pathways, COP cells have a similar expression pattern to BM-MSCs and ASCs.

CONCLUSION

COP cells are a unique but functionally similar population to BM-MSCs and ASCs, sharing their proliferation and differentiation capacity, thus presenting an accessible source of MSCs with strong potential for translational regenerative medicine strategies.

Adenylosuccinic Acid Is a Non-Toxic Small Molecule In Vitro and In Vivo

Adenylosuccinic acid (ASA) is a small molecule dicarboxylate that could be a strong clinical development candidate for inherited myopathies involving dysregulated purine nucleotide metabolism. Currently, there are no published pharmacokinetic/dynamic or toxicology data available, although 10-year clinical trial data on Duchenne muscular dystrophy patients suggests it is a chronically safe drug. In this study, we tested the toxicity of ASA to cultured myoblasts in vitro and its acute systemic toxicity in mice. ASA is a non-toxic small molecule with an LD50 > 5000 mg/kg. Some background necrotic foci in the liver, kidney and gastrointestinal tract were shown that are likely incidental but warrant follow-up sub-/chronic oral exposure studies.

Diagnostic power of relative sit-to-stand muscle power, grip strength, and gait speed for identifying a history of recurrent falls and fractures in older adults

PURPOSE

To compare the diagnostic value of relative sit-to-stand muscle power with grip strength or gait speed for identifying a history of recurrent falls and fractures in older adults.

METHODS

Data from an outpatient clinic included anthropometry (height/weight), bone density, 5 times sit-to-stand time (stopwatch and standardized chair), grip strength (hydraulic dynamometer), and gait speed (4 m). Relative sit-to-stand muscle power (W.kg^-1, normalised to body mass) was calculated using a validated equation. Outcomes of falls (past 1 year) and fractures (past 5 years) were self-reported and verified by medical records wherever possible. Binary logistic regression considering for potential confounders (age, sex, BMI, Charlson comorbidity index, femoral neck bone density) and receiver operating characteristics (ROC) curves were used in statistical analysis.

RESULTS

508 community-dwelling older adults (median age: 78 years, interquartile range: 72, 83, 75.2% women) were included. Compared to greater relative sit-to-stand muscle power (1.62-3.78W.kg^-1 for women; 2.03-3.90W.kg^-1 for men), those with extremely low relative sit-to-stand muscle power were 2.35 (95% CI 1.54, 3.60, p < 0.001) and 2.41 (95% CI 1.25, 4.65, p = 0.009) times more likely to experience recurrent falls and fractures, respectively, in fully adjusted model. Compared to grip strength or gait speed, relative sit-to-stand muscle power showed the highest area under the ROC curve for identifying recurrent falls (AUC: 0.64) and fractures (AUC: 0.62). All tests showed low diagnostic power (AUC: < 0.7).

CONCLUSION

Relative sit-to-stand muscle power performed slightly (but not statistically) better than grip strength or gait speed for identifying a history of recurrent falls and fractures in older adults. However, all tests showed low diagnostic power.