General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms cancer was higher in the intervention (4.3%) group than control (3.6%) group, but there was no significant difference in prostate cancer mortality (intervention, 0.29% vs. control, 0.29%) after a median follow-up of 10-years. Meaning:The CAP single PSA-screen intervention detected more prostate cancer cases, but after a median of 10-years' follow-up has, thus far, had no significant effect on prostate cancer mortality. Conclusion and relevance:Among practices randomized to a low-intensity PSA screening intervention compared with standard practice, there was no significant difference in prostate cancer mortality after a 4 median 10-years follow up, but the detection of low-risk prostate cancers increased. Although longer-term follow-up is in progress, the current findings do not support single PSA-testing for population-based screening.

The selection and collection of single cells from within a heterogeneous population is required to produce genetically engineered cell lines, to develop new stem cell lines, and for single-cell studies. We describe a new platform for the positive selection of single live mammalian cells while the cells remain adherent to their growth surface. Cells were grown on arrays of microfabricated, releasable elements composed of SU-8 polymer termed "cell pallets". The presence of air between the elements restricted the cells to the top surfaces of the pallets. Single pallets situated within large arrays of pallets were released on demand using a single, focused, laser pulse. The laser pulses were low in energy (2-5 muJ) and did not detach nearby, nontargeted pallets. Since the SU-8 pallets and the underlying glass substrate were optically transparent, the cells on the pallets could be visualized by microscopy before and after release. Over 90% of cells remained attached to the pallet during laser-based release. The feasibility of growing the cells from the released pallets into clonal colonies was demonstrated. The pallet array system permits adherent cells to be inspected using conventional microscopy and selected cells released for further analysis. The ability to assess cells while they remain adherent to a surface will broaden the number of attributes that can be utilized for cell separation, for example, cell shape, cytoskeletal properties, and other attributes.

The ability to selectively grow out individual cells possessing unique characteristics from within a mixed population is of widespread importance for biomedical investigations. Generation of genetically engineered cell lines, transformation studies, cell-based assays, and stem cell studies are examples where single-cell cloning is of immense value. The vast majority of mammalian cells grow adherent to a surface; therefore, positive selection followed by cloning of cells while the cells remain adherent to their growth surface is an important goal. We recently demonstrated a microfabricated cell array combined with laser-based release of individual array elements for positive selection of single cells. In the current work, a strategy to collect single cells for clonal expansion is described. The system enabled cloning of individual cells with 80-90% efficiency. Single cells were selected and cloned from small populations of fewer than 10,000 cells. Strategies used by cells to migrate from the pallets to form colonies on the surface of the collection device were examined. Implementation of encoded array elements made it possible to follow specific cells throughout the selection, collection, and cloning procedure. Thus, a particular cell can be identified by any number of imaging techniques, isolated, and clonally expanded to generate a homogeneous cell line or a pure sample for genetic or biochemical analysis.

Cit a tio n fo r fin al p u blis h e d ve r sio n: H a m dy, F r e d di e C., Do n ov a n, Je n ny L., La n e, J. Ath e n e , M e t c alf e, C h ri s, D avis, Mi c h a el, T u r n er, E m m a L., M a r ti n, Ric h a r d M .