Engineered bone marrow as a clinically relevant ex vivo model for primary bone cancer research and drug screening.

Osteosarcoma (OS) is the most common primary malignant bone cancer in children and adolescents. While numerous other cancers now have promising therapeutic advances, treatment options for OS have remained unchanged since the advent of standard chemotherapeutics and offer less than a 25% 5-y survival rate for those with metastatic disease. This dearth of clinical progress underscores a lack of understanding of OS progression and necessitates the study of this disease in an innovative system. Here, we adapt a previously described engineered bone marrow (eBM) construct for use as a three-dimensional platform to study how microenvironmental and immune factors affect OS tumor progression. We form eBM by implanting acellular bone-forming materials in mice and explanting the cellularized constructs after 8 wk for study. We interrogate the influence of the anatomical implantation site on eBM tissue quality, test ex vivo stability under normoxic (5% O2) and standard (21% O2) culture conditions, culture OS cells within these constructs, and compare them to human OS samples. We show that eBM stably recapitulates the composition of native bone marrow. OS cells exhibit differential behavior dependent on metastatic potential when cultured in eBM, thus mimicking in vivo conditions. Furthermore, we highlight the clinical applicability of eBM as a drug-screening platform through doxorubicin treatment and show that eBM confers a protective effect on OS cells that parallel clinical responses. Combined, this work presents eBM as a cellular construct that mimics the complex bone marrow environment that is useful for mechanistic bone cancer research and drug screening.

The rate-limiting step: the provision of safe anesthesia in low-income countries.

BACKGROUND: The importance of safe anesthesia for the best possible surgical outcomes in every patient is not disputed in high resource settings. Low-income countries lag far behind in the provision of, and training for, safe anesthesia practice. Too little is known about numbers and types of providers in a majority of low-income countries. METHODS: A review of the member societies of the World Federation of Societies of Anaesthesiologists was undertaken, and membership statistics of national societies were requested. Of the 126 members of the federation, only 14 represent low-income countries. Many non-federation-member countries are also low-income countries. RESULTS: The anesthesia infrastructure and personnel challenges in low-income countries contribute to poor patient outcomes and limited access to emergency and essential surgery. The presence of a functional anesthesia society provides a measure of the numbers of providers and a snapshot of local professional activities. CONCLUSION: The establishment and maintenance of an anesthesia society is an indicator of respect for the profession and commitment to standards of practice, quality initiatives, and continuing medical education within the country.

Extracellular matrix production and oxygen diffusion regulate chemotherapeutic response in osteosarcoma spheroids.

BACKGROUND: Osteosarcoma (OS) survival rates and outcome have not improved in 50 years since the advent of modern chemotherapeutics. Thus, there is a critical need for an improved understanding of the tumor microenvironment to identify better therapies. Extracellular matrix (ECM) deposition and hypoxia are known to abrogate the efficacy of various chemical and cell-based therapeutics. Here, we aim to mechanistically investigate the combinatorial effects of hypoxia and matrix deposition with the use of OS spheroids. METHODS: We use two murine OS cell lines with differential metastatic potential to form spheroids. We form spheroids of two sizes, use ascorbate-2-phosphate supplementation to enhance ECM deposition, and study cell response under standard (21% O2) and physiologic (5% O2) oxygen tensions. Finally, we examine chemotherapeutic responses to doxorubicin treatment. RESULTS: ECM production and oxygen tension are key determinants of spheroid size through cell organization based on nutrient and oxygen distribution. Interestingly, highly metastatic OS is more susceptible to chemotherapeutics compared to less metastatic OS when matrix production increases. Together, these data suggest that dynamic interactions between ECM production and oxygen diffusion may result in distinct chemotherapeutic responses despite inherent tumor aggressiveness. CONCLUSION: This work establishes OS spheroids as a valuable tool for early OS tumor formation investigation and holds potential for novel therapeutic target and prognostic indicator discovery.