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:The treatment of bone defects caused by infection, trauma or neoplasms remains a clinical challenge. Autologous bone transplantation is limited by availability, donor site morbidity and surgical risk factors. This has given rise to stromal/stem-cell based therapy. Bone marrow derived stromal cells (BMSCs) have been studied to a large extent and show high regenerative potential but their use is limited by availability, donor site morbidity and the relatively low cell yield as they represent only <0.1% of cell harvested from bone marrow aspirate. At the same time, they are the closest mesenchymal stromal cells for bone tissue engineering given their tissue origin and, unlike other mesenchymal stromal cells, can support the formation of hematopoietic marrow. Adipose tissue derived stromal cells (ASCs) as part of the stromal vascular fraction of adipose tissue can as well undergo osteogenic differentiation but can be additionally isolated in a sufficient quantity from lipoaspirate after liposuction of abundant subcutaneous fat tissue. Here, it has been shown that there are no major differences in regard to proliferation or differentiation capacity of ASCs derived from subcutaneous fat of different anatomical regions. It has been shown that BMSCs are more prone to senescence during expansion and passage than ASCs and that ageing impacts proliferative capabilities of BMSCs more than that of ASCs while it has also been reported that osteogenic differentiation capacity is least impacted by age. Multiple studies have compared the characteristics of these two mesenchymal stromal cells in regard to bone tissue engineering in vitro. Most studies point to inferior extracellular matrix mineralization and lower expression of key osteogenic transcription markers like Runx2 in osteogenic differentiated ASCs compared to BMSCs. On the other hand, a study by Rath et al. found contrary results using particular culturing conditions like 3D bioglass scaffolds. An intraindividual comparison of human MSCs of three donors cultured on decellularized porcine bone confirmed superior osteogenic capacity of BMSCs compared to ASCs. In contrast to BMSCs, ASCs were not able to induce heterogenic ossification in a mouse model. In a sheep tibia defect model application of BMSCs resulted in a significantly higher amount of newly formed bone tissue. Importantly, Osteogenic differentiated ASCs do not support the formation of a hematopoietic marrow. Proteomics enables large-scale analysis of proteins present in a cell type and can be used to identify differentially regulated key proteins in a comparative approach. A comparative proteomic analysis of BMSCs and ASCs by Roche et al. in 2009 identified 556 proteins with 78% of these not being differentially regulated between these two cell populations, regarded as high similarity. Another comparative proteomic study of 2016 by Jeon et al. found 90 differentially regulated proteins out of 3000 total identified proteins. Both studies do not specify a number of different tissue donors and in part using cell lines. Looking for differences upon osteogenic differentiation, transcriptomic comparison of osteogenic differentiated porcine ASCs and BMSCs has been performed, resulting in 21 differentially expressed genes after 21 days of osteogenic culture conditions. Still, it remains unanswered, which are the key distinctive features of osteogenic differentiated ASCs and BMSCs at protein level that might help address the abovementioned weaknesses of ASCs in bone tissue engineering/regeneration for translational research. To overcome this need, an intraindividual comparative DIA based proteomic analysis of osteogenic differentiated human BMSC and ASCs was performed in this study.

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Homo sapiens

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