骨肉瘤（OS）是儿童和青少年中最常见的原发性骨恶性肿瘤。虽然现在许多其他癌症已经取得了有希望的治疗进展，但骨肉瘤的治疗选择自从常规化疗药物问世以来没有改变，并且对于那些有转移性疾病的患者，仅提供不到25%的5年生存率。临床进展的不足凸显了对骨肉瘤进展的理解不足，并需要在创新的系统中研究这种疾病。在这里，我们改进了先前描述的工程骨髓（eBM）构建，用作研究微环境和免疫因素如何影响骨肉瘤肿瘤进展的三维平台。我们通过在小鼠中植入非细胞骨形成材料并在8周后切取细胞化的构建物进行研究来形成eBM。我们调查了解剖植入部位对eBM组织质量的影响，测试了在常氧（5% O2）和标准（21% O2）培养条件下体外稳定性，培养骨肉瘤细胞在这些构建物中，并将其与人骨肉瘤样本进行比较。我们展示了eBM能够稳定地重现原生骨髓的组成。当在eBM中培养时，骨肉瘤细胞的表现呈现不同，取决于其转移潜能，从而模拟了体内条件。此外，我们通过多柔比星处理突出了eBM作为药物筛选平台的临床适用性，并展示了eBM对骨肉瘤细胞具有与临床反应相似的保护效应。总之，这项工作提出了eBM作为细胞构建物，模拟了复杂的骨髓环境，可用于机械性骨癌研究和药物筛选。

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.