Search

Circulating tumor cells (CTCs) play a central role in cancer metastasis and represent a rich source of data for cancer prognostics and therapeutic guidance. Reliable CTC recovery from whole blood therefore promises a less invasive and more sensitive approach to cancer diagnosis and progression tracking. CTCs, however, are exceedingly rare in whole blood, making their quantitative recovery challenging. Several techniques capable of isolating these rare cells have been introduced and validated, yet most suffer from low CTC purity or viability, both of which are essential to develop a clinically viable CTC isolation platform. To address these limitations, we introduce a patterned, immunofunctional, photodegradable poly(ethylene glycol) (PEG) hydrogel capture surface for the isolation and selective release of rare cell populations. Flat and herringbone capture surfaces were successfully patterned via PDMS micromolding and photopolymerization of photolabile PEG hydrogels. Patterned herringbone surfaces, designed to convectively transport cells to the capture surface, exhibited improved capture density relative to flat surfaces for target cell capture from buffer, buffy coat, and whole blood. Uniquely, captured cells were released for collection by degrading the hydrogel capture surface with either bulk or targeted irradiation with cytocompatible doses of long wavelength UV light. Recovered cells remained viable following capture and release and exhibited similar growth rates as untreated control cells. The implementation of molded photodegradable PEG hydrogels as a CTC capture surface provides a micropatternable, cytocompatible platform that imparts the unique ability to recover pure, viable CTC samples by selectively releasing target cells., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The microfabrication of microfluidic control systems and the development of increasingly sensitive molecular amplification tools have enabled the miniaturization of single cells analytical platforms. Only recently has the throughput of these platforms increased to a level at which populations can be screened at the single cell level. Techniques based upon both active and passive manipulation are now capable of discriminating between single cell phenotypes for sorting, diagnostic or prognostic applications in a variety of clinical scenarios. The introduction of multiphase microfluidics enables the segmentation of single cells into biochemically discrete picoliter environments. The combination of these techniques are enabling a class of single cell analytical platforms within great potential for data driven biomedicine, genomics and transcriptomics., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Genetic modification of hematopoietic stem cells often results in the expression of foreign proteins in pluripotent progenitor cells and their progeny. However, the potential for products of foreign genes introduced into hematopoietic stem cells to induce host immune responses is not well understood. Gene marking and induction of immune responses to enhanced green fluorescent protein (eGFP) were examined in rhesus macaques that underwent nonmyeloablative irradiation followed by infusions of CD34(+) bone marrow cells transduced with a retroviral vector expressing eGFP. CD34(+) cells were obtained from untreated animals or from animals treated with recombinant human granulocyte colony-stimulating factor (G-CSF) alone or G-CSF and recombinant human stem cell factor. Levels of eGFP-expressing cells detected by flow cytometry peaked at 0.1% to 0.5% of all leukocytes 1 to 4 weeks after transplantation. Proviral DNA was detected in 0% to 17% of bone marrow--derived colony-forming units at periods of 5 to 18 weeks after transplantation. However, 5 of 6 animals studied demonstrated a vigorous eGFP-specific cytotoxic T lymphocyte (CTL) response that was associated with a loss of genetically modified cells in peripheral blood, as demonstrated by both flow cytometry and polymerase chain reaction. The eGFP-specific CTL responses were MHC-restricted, mediated by CD8(+) lymphocytes, and directed against multiple epitopes. eGFP-specific CTLs were able to efficiently lyse autologous CD34(+) cells expressing eGFP. Antibody responses to eGFP were detected in 3 of 6 animals. These data document the potential for foreign proteins expressed in CD34(+) hematopoietic cells and their progeny to induce antibody and CTL responses in the setting of a clinically applicable transplantation protocol. (Blood. 2001;97:1951-1959)