Enhanced Leukemia Cell Detection Using a Novel Magnetic Needle and Nanoparticles

Abstract

Acute leukemia is a hematopoietic malignancy for which the accurate measurement of minimal residual disease is critical to determining prognosis and treatment. Although bone marrow aspiration and light microscopy remain the current standard of care for detecting residual disease, these approaches cannot reliably discriminate less than 5% lymphoblast cells. To improve the detection of leukemia cells in the marrow, we developed a novel apparatus that utilizes antibodies conjugated to superparamagnetic iron oxide nanoparticles (SPION) and directed against the acute leukemia antigen CD34, coupled with a "magnetic needle" biopsy. Leukemia cell lines expressing high or minimal CD34 were incubated with anti-CD34-conjugated SPIONs. Three separate approaches including microscopy, superconducting quantum interference device magnetometry, and in vitro magnetic needle extraction were then used to assess cell sampling. We found that CD34-conjugated nanoparticles preferentially bind high CD34-expressing cell lines. Furthermore, the magnetic needle enabled identification of both cell line and patient leukemia cells diluted into normal blood at concentrations below those normally found in remission marrow samples. Finally, the magnetic needle enhanced the percentage of lymphoblasts detectable by light microscopy by 10-fold in samples of fresh bone marrow aspirate approximating minimal residual disease. These data suggest that bone marrow biopsy using antigen-targeted magnetic nanoparticles and a magnetic needle for the evaluation of minimal residual disease in CD34-positive acute leukemias can significantly enhance sensitivity compared with the current standard of care.

Selective Nanoparticles in Microextraction

“…The use of MNPs coated with anti-CD34 antibody can improve this performance. (38,39) This type of NPs presents a high affinity toward leukemia cells as it has been proved by imaging, when a leukemia cell line (U9337) is incubated with immuno-MNPs and bare-MNPs (unconjugated NPs). The immuno-MNPs bind to the cell surface due to the antigen recognition, while no (visual) interaction is observed for the bare-MNPs.…”

Nanopharmaceuticals (part 2): products in the pipeline

“…CD34-SPION-carrying leukemia cells are collected using a magnetic needle, followed by the magnetization of the NPs using a pulse field, which enables their detection by SQUID as they relax back to equilibrium. 38 Anti-CD34-conjugated NPs can be prepared by incubating carboxyl groups-bearing commercially available magnetite NPs at an acidic pH and room temperature with EDC and N-hydroxysulfosuccinimide, followed by raising the pH to 8 and adding the anti-CD34 antibody. 38,39 TEM studies have shown that the conjugation reaction has no impact on the Ferret diameter of the commercially available NPs.…”

“…38 Anti-CD34-conjugated NPs can be prepared by incubating carboxyl groups-bearing commercially available magnetite NPs at an acidic pH and room temperature with EDC and N-hydroxysulfosuccinimide, followed by raising the pH to 8 and adding the anti-CD34 antibody. 38,39 TEM studies have shown that the conjugation reaction has no impact on the Ferret diameter of the commercially available NPs. The surface modification with protein (CD34 antibodies), however, increases the particle's hydrodynamic diameter to approximately 70 nm, when measured by DLS.…”

Modeling the efficiency of a magnetic needle for collecting magnetic cells

“…Areas of medical research in which specific isolation by magnetic separation have been proposed include stem cell isolation from cord blood (Laitinen and Laine 2007), isolation and quantification of circulating tumors cells from solid tumors shed into blood (Mi et al 2011, Weissenstein et al 2012) and isolation of rare lymphoblasts from bone marrow in leukemia (Jaeteo et al 2009). As new utilities are discovered for isolating and quantifying cells collected from blood and bone marrow, there is a growing and critical need to understand the physical features important for collection.…”

“…Here we examine a simple method involving the collection of magnetic nanoparticle-coated polystyrene microspheres, which mimic nanoparticle-coated cells, using a magnetic needle (Bryant et al 2007, Adolphi et al 2009, Jaetao et al 2009) inserted into the sample fluid. The size of the polystyrene spheres were chosen to be 9.65 μm, within the 7–12 μm size range for white blood cells, a common target for cell collection out of blood and bone marrow.…”