Abstract 5356: 3D tissue-engineered bone marrow niche as novel method to study pathophysiology and drug resistance in multiple myeloma
Authors: de la Puente Pilar , Gilson Rebecca , Muz Barbara , Azab Feda , King Justin , Achilefu Samuel , Vij Ravi , Azab Abdel Kareem 
Published: August 2015

Abstract
INTRODUCTION: Current methods to assess multiple myeloma (MM) cancer treatments are often inaccurate, in part, due to these methods cannot take into consideration the variability of every patient, and fail to recreate the bone marrow (BM) microenvironment. In this study we developed a patient-derived three-dimensional tissue-engineered BM (3DTEBM) niche as novel model that will allow better evaluation of interactions of MM cells and their microenvironment and how these interactions may affect MM drug resistance in the specific patient.
METHODS & RESULTS: 3DTEBM cultures were made by crosslinking of patient-derived BM supernatants; the 3D-scaffold included MM cell lines or primary CD138+ MM cells and other accessory cells (stromal cells and endothelial cells, or CD138- cells). 3DTEBM cultures were studied for cell proliferation by flow cytometry, and compared with 2D cultures and other commercial 3D systems including PLGA microspheres, Algimatrix, and Matrigel, and imaged for 2 weeks using a confocal microscope. 3DTEBM cultures promoted the proliferation of MM cells more than 2D cultures and commercial 3D systems. 3DTEBM cultures supported the growth of fresh and frozen primary MM cells and allowed the use of these cells ex vivo at least 2 weeks. In addition, we found a natural development of polarization in the cellularity of the scaffold, with the bottom rich of stromal cells, top rich of endothelial cells, and MM cells through all the parts of the scaffold, reflecting the pathophysiological development of MM in the BM niche.
The effect of 3DTEBM cultures on cytokine expression was determined by cytokine antibody arrays and 3D-tissue depth effects in drug gradients, oxygenation levels and proliferation (HIF-1α, PIM, Ki67, CXCR4, and CD138 expression) were determined using flow cytometry or IHC. 3DTEBM cultures showed that 23 out of 80 cytokines tested were highly expressed with at least 3-fold increase in the 3D cultures vs 2D cultures. Furthermore, 3DTEBM cultures recreated the BM niche drug gradients and oxygenation levels due to depth of tissue; MM cells showed lower drug uptake and higher hypoxia levels (PIM and HIF-1α) with depth of tissue, and hypoxia-associated decreased CD138 and increased CXCR4 expression. We also found that MM cells were quiescent (lower Ki67 expression) in the hypoxic niche.
Finally, drug resistance of MM cell lines or primary MM cells in 3DTEBM cultures was analyzed by flow cytometry. 3DTEBM cultures induced drug resistance in MM cells more than 2D cultures and commercial 3D systems, and preliminary results indicate that drug resistance profile in the 3DTEBM matched the clinical manifestation of the disease in the specific patient, while 2D cultures did not.
CONCLUSION: The patient-derived 3DTEBM is a more biologically relevant model for evaluation of interactions of MM cells and their microenvironment in the BM niche, especially in the context of drug resistance.
Citation Format: Pilar de la Puente, Rebecca Gilson, Barbara Muz, Feda Azab, Justin King, Samuel Achilefu, Ravi Vij, Abdel Kareem Azab. 3D tissue-engineered bone marrow niche as novel method to study pathophysiology and drug resistance in multiple myeloma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5356. doi:10.1158/1538-7445.AM2015-5356