Project description:The unique properties of the bone marrow allow for migration and proliferation of multipl myeloma (MM) cells, while also providing the perfect environment for development of quiescent, drug-resistant MM cell clones. Bone marrow adipocytes (BMAds), which have recently been identified as important contributors to systemic adipokine levels, bone strength, hematopoiesis, and progression of metastatic and primary bone marrow cancers, such as MM. Recent studies in myeloma suggest that BMAds can be reprogrammed by tumor cells to contribute to myeloma-induced bone disease, and reciprocally, BMAds support MM cells in vitro. Importantly, most data investigating BMAds have been generated using adipocytes derived by differentiating bone marrow-derived mesenchymal stromal cells (MSCs) into adipocytes in vitro using adipogenic media, due to the extreme technical challenges associated with isolating and culturing primary adipocytes. However, if studies could be performed with primary adipocytes, they likely will recapitulate in vivo biology better than MSC-derived adipocyte, as the differentiation process is artificial and differs from in vivo differentiation, and progenitor cell(s) of the primary BMAd may not be the same as the MSCs precursors used for adipogenic differentiation in vitro. Therefore, we developed and refined three methods for culturing primary BMAds (pBMAds): 2D coverslips, 2D transwells, and 3D silk scaffolds, all of which can be cultured alone or with MM cells to investigate bidirectional tumor-host signaling. To develop an in vitro model with a tissue-like structure to mimic the bone marrow microenvironment, we developed the first 3D, tissue engineered model utilizing pBMAds derived from human bone marrow. We found that pBMAds, which are extremely fragile, can be isolated and stably cultured in 2D for 10 days and in 3D for short term (~2 weeks) or long term (1 month) in vitro. To investigate the relationship between pBMAds and myeloma, MM cells can be added to investigate physical relationships through confocal imaging and soluble signaling molecules via mass spectrometry. In sum, we developed three in vitro cell culture systems to study primary bone marrow adipocytes and myeloma cells, which could be adapted to investigate many diseases and biological processes involving the bone marrow, including other bone-homing tumor types.

Project description:Development of systems allowing the maintenance of native properties of mesenchymal stromal cells (MSC) is a critical challenge for studying physiological functions of skeletal progenitors, as well as towards cellular therapy and regenerative medicine applications. Conventional stem cell culture in monolayer on plastic dishes (2D) is associated with progressive loss of functionality, likely due to the absence of a biomimetic microenvironment and the selection of adherent populations. Here we demonstrate that 2D MSC expansion can be entirely bypassed by culturing freshly isolated bone marrow cells within the pores of 3D scaffolds in a perfusion-based bioreactor system, followed by enzymatic digestion for cell retrieval. The 3D-perfusion system supported MSC growth while maintaining cells of the hematopoietic lineage, and thus generated a cellular environment mimicking some features of the bone marrow stroma. As compared to 2D-expansion, sorted CD45- cells derived from 3D-perfusion culture after the same time (3 weeks) or a similar extent of proliferation (7-8 doublings) maintained a 4.3-fold higher clonogenicity and exhibited a superior differentiation capacity towards all typical mesenchymal lineages, with similar immunomodulatory function in vitro. Transcriptomic analysis performed on MSC from 5 donors validated the robustness of the process and indicated a reduced inter-donor variability as well as a significant upregulation of multipotency-related gene clusters following 3D-perfusion as compared to 2D expansion. The described system offers a model to study how factors of a 3D engineered niche may regulate MSC function and, by streamlining conventional labor-intensive processes, is prone to automation and scalability within closed bioreactor systems. Nucleated cells were isolated from 5 fresh human bone marrow aspirates by means of red blood cells lyses buffer and then were seeded into a 3D perfusion bioreactor system using a pure hydroxyapatite 3D scaffold and in conventional Petri dishes (2D). After culture for 19 days, cells from both systems were enzymatically retrieved and sorted using anti-CD45-coated magnetic beads. Total RNA was extracted from CD45- cells, QCed and hybridized to Affymetrix microarrays.

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Homo sapiens

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