An Organotypic High Throughput System for Characterization of Drug Sensitivity of Primary Multiple Myeloma Cells

Summary

We describe a high-throughput drug sensitivity assay for primary multiple myeloma cells. It consists of a reconstruction of the bone marrow microenvironment (including extracellular matrix and stroma) in multi-well plates, and a non-invasive method for longitudinal quantification of cell viability.

Abstract

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and heterogeneity of patient-derived multiple myeloma (MM) cells. This approach consists in seeding primary MM cells freshly extracted from bone marrow aspirates into microfluidic chambers implemented in multi-well plates, each consisting of a reconstruction of the bone marrow microenvironment, including extracellular matrix (collagen or basement membrane matrix) and stroma (patient-derived mesenchymal stem cells) or human-derived endothelial cells (HUVECs). The chambers are drugged with different agents and concentrations, and are imaged sequentially for 96 hr through bright field microscopy, in a motorized microscope equipped with a digital camera. Digital image analysis software detects live and dead cells from presence or absence of membrane motion, and generates curves of change in viability as a function of drug concentration and exposure time. We use a computational model to determine the parameters of chemosensitivity of the tumor population to each drug, as well as the number of sub-populations present as a measure of tumor heterogeneity. These patient-tailored models can then be used to simulate therapeutic regimens and estimate clinical response.

Introduction

The goal of this method is to characterize the drug sensitivity of multiple myeloma (MM) primary cells to a panel of agents ex vivo, as close as possible to physiological conditions, and with sufficient precision that these results can be used to identify chemoresistant sub-populations within the tumor burden and, ultimately, to parameterize computational models designed to estimate clinical response.

Computational models are powerful tools to analyze complex systems, such as cancer-host-therapy interactions. However, models are only as good as the data used to parameterize them. Unfortunately, most data available in literature can....

Protocol

The use of human cells derived from biopsies as described below was approved by Moffitt’s Institutional Review Board and conducted under the clinical trial MCC# 14745 conducted at the H. Lee Moffitt Cancer Center and Research Institute.

1. Sorting of MM Cells from Bone Marrow Aspirates

1. Collect bone marrow aspirates (20 ml) from patients in sodium heparin syringe.
2. Isolate mononuclear cells by centrifuging diluted marrow (1:1 with sterile PBS) over a sterile aqueous medium centrifugation gradient at 400 x g for 30 min at ambient temperature.
3. Collect the interface, which contains the mononuclear cells. Was....

Results

The flow of the experiment is briefly described in Figure 1. If all steps are completed successfully, the images obtained by the microscope should be equivalent to Figure 2: live MM cells should be clearly seen as bright disks and BMSCs or HUVECs should be barely visible and well distributed in the background. As seen in Figure 2A, MM cells range in size from one patient to the other, but in general they are smaller than cell lines. Since they practically do not replicat.......

Discussion

In summary, this is a powerful and high throughput method to quantify chemosensitivity of primary MM cells and ex vivo pharmacodynamics of drugs in a reconstruction of the bone marrow. The critical steps within this protocol are the proper seeding of the wells and adequate focusing (see Figure 2 for expected results): ensure that MM and stromal cells are uniformly distributed, that stromal cells are adherent to the bottom of the well, that all MM cells are in the same focal plane, and that MM ce.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
EVOS FL AUTO	AMG	AMAFD1000 + AMC1000	Digital microscope equipped with motorized stage and bench top incubator.
384-well plate CellBind	CORNING	CLS3683 SIGMA	Corning CellBIND 384 well plates 384 well plate, polystyrene, CellBIND surface, sterile, clear flat bottom, black, w/lid
1,536-well plate CellBind	CORNING	CLS3832 ALDRICH	Corning 1,536 well plates, low base, surface treatment CellBIND, sterile
Ficoll-Paque Plus	GE Healthcare	GE17-1440-02 SIGMA	For in vitro isolation of lymphocytes from human peripheral blood.
CD138 magnetic beads	Miltenyi	130-051-301	Antibody conjugated magnetic beads for selection of CD138+ cells.
LS columns	Miltenyi	130-042-401	Column for separation of cells.
MidiMACS Separator	Miltenyi	130-042-302	Magnet for separation column.
Matrigel	Sigma-Aldrich	E6909 SIGMA	ECM Gel from Engelbreth-Holm-Swarm murine sarcoma
Getrex	Life Technologies	A1413201	LDEV-Free Reduced Growth Factor Basement Membrane Matrix
HUVEC	Life Technologies	C-003-25P-B	Human Umbilical Vein Endothelial Cells (HUVEC )
RPMI-1640 media	GIBCO	11875-093	RPMI 1640 Medium + L-Glutamine + Phenol Red
FBS Heat inactivated	GIBCO	10082-147	Fetal Bovine Serum, certified, heat inactivated, US origin
3.1 mg/ml Bovine collagen type I	Advanced Biomatrix	5005-B	Bovine Collagen Solution, Type I, 3 mg/ml, 100 ml
Precision XS	BIOTEK	PRC3841	Robotic pipettor system