Speaker
Description
Introduction
Plasma cell malignancy - multiple myeloma (MM), occurs primarily in the bone marrow (BM) and appears to be strongly regulated by interactions with BM mesenchymal stromal cells (MSCs). In addition, collagen is an important constituent of the BM environment and provides not only structural, but functional support to many of its cells. Improved understanding of MM pathology requires a development of 3D models that can recapitulate the BM-supported MM survival and intercellular communication. Therefore, we aimed to establish a collagen-based 3D co-culture model of MM cells and MSCs.
Methodology
MSCs were obtained from BM of patients undergoing total hip arthroplasty. For 3D co-culture, MSCs and semi-adherent MM cells (MM1.S) were grown in hydrogels generated using rat-tail collagen type I. For mono-cultures, 3 x 105 cells were cultured per 100 µl of collagen, whereas in co-culture, the cells are seeded in an initial one to one ratio, giving a total of 3 x 105 cells (2D controls were performed in parallel). Viability and metabolic activity of encapsulated cells were examined performing an MTT assay and measuring ATP concentration at 1, 3 and 7 days of culture. Gene expression was assessed by qPCR and proliferation evaluated using flow cytometry. Immunohistochemistry was performed to identify functional marker changes. Finally, clonogenic capacity of both cell types was determined after retrieval from collagen gels.
Results
Both MM1.S cells and MSCs were successfully encapsulated and cultured in collagen gels. Upon day 7, the portion of MM1.S cells exceeded the percentage of MSCs in the 3D co-culture system, where MM1.S cells accounted for about two-thirds of total retrieved cells. The viability of the cells did not seem to be affected by a collagen-based environment. However, the proliferation of MM1.S cells appeared changed, with a decreased Ki-67high fraction of MM1.S cells growing in 3D culture, suggesting a attenuated proliferation potential, regardless of the presence of MSCs. Reduced metabolic activity and ATP production were observed in 3D cultured MM1.S cells and MSCs in comparison to standard 2D culture. In addition, MM1.S cells recovered from 3D collagen cultures showed a higher clonogenic potential when compared to 2D cultures.
Conclusion
Here, we established a physiologically relevant model system to co-culture semi-adherent MM cells and MSCs. The collagen-supported 3D co-culture of BM myeloma cells and MSCs might alter their behavior, governing MM cell viability and clonogenicity, in a manner different to conventional 2D systems. Further optimization of the 3D co-culture will provide significant insights in the behavior of MM cells and, ideally, their response to anti-cancer treatments.
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