Immunocapture of prostate cancer cells by use of anti-PSMA antibodies in microdevices

Abstract

Patients suffering from cancer can shed tumor cells into the bloodstream, leading to one of the most important mechanisms of metastasis. As such, the capture of these cells is of great interest. Circulating tumor cells are typically extracted from circulation through positive selection with the epithelial cell-adhesion molecule (EpCAM), leading to currently unknown biases when cells are undergoing epithelial-to-mesenchymal transition. For prostate cancer, prostate-specific membrane antigen (PSMA) presents a compelling target for immunocapture, as PSMA levels increase in higher-grade cancers and metastatic disease and are specific to the prostate epithelium. This study uses monoclonal antibodies J591 and J415—antibodies that are highly specific for intact extracellular domains of PSMA on live cells— in microfluidic devices for the capture of LNCaPs, a PSMA-expressing immortalized prostate cancer cell line, over a range of concentrations and shear stresses relevant to immunocapture. Our results show that J591 outperforms J415 and a mix of the two for prostate cancer capture, and that capture performance saturates following incubation with antibody concentrations of 10 micrograms per milliliter.

Characterization of a hybrid dielectrophoresis and immunocapture microfluidic system for cancer cell capture

“…Our Hele-Shaw flow cell is similar to but refined relative to previous designs [46][47][48][49]. The device geometry includes sidewalls that are sections of rectangular hyperbolas [47], which replicate the far field of a stagnation flow impinging on the coordinate origin of the hyperbolas.…”

“…The Hele-Shaw flow cell allows for characterization of cell adhesion as a function of shear stresses corresponding to those experienced by cells in immunocapture devices [9,46,49]. To compare immunocapture performance of LNCaPs with and without DEP effects, interdigitated array (IDA) electrodes were fabricated along the length of the Hele-Shaw flow cell on only one side of its central axis ( Figure 1).…”

“…This antibody has been shown to have high specificity for PSMA [45], and its use in the analysis of immunocapture performance of LNCaPs was characterized over a range of concentrations and shear stresses [46]. Additionally, J591 has been used to demonstrate high-efficiency immunocapture of prostate CTCs from prostate cancer patient blood samples [9,17].…”

“…Additionally, J591 has been used to demonstrate high-efficiency immunocapture of prostate CTCs from prostate cancer patient blood samples [9,17]. The glass surface of the Hele-Shaw flow cell was functionalized to immobilize the antibody using MPTMS-GMBS-NeutrAvidin-biotin chemistry following previously reported protocols [17,46].…”

“…In this study, we characterized the performance of a hybrid DEP-immunocapture system by quantifying cell adhesion to immunocapture surfaces as a function of the local shear stress experienced by cells. This characterization of the shear-dependence of immunocapture was performed in a Hele-Shaw flow cell using a prostate cancer cell line, LNCaP, and the monoclonal antibody, J591, which is highly specific to PSMA [45,46]. We show that, depending on the applied electric field frequency, DEP effects can control the capture performance of prostate cancer cells by attracting them to or repelling them from immunocapture surfaces.…”