A system that integrates pulsed laser microbeam irradiation and polymer microdevices is expected to lead to a greater understanding of cellular behavior and disease progression.

The technology, known as iCell, was developed by a research and development team at Tustin, CA-based , LightWorks Optics, Inc, a maker of advanced optics systems for biomedical companies. Collaborating with the University of California Irvine, LightWorks was awarded a grant through the National Institute of Health's (NIH) Small Business Innovation Research (SBIR) "Lab to Marketplace" program.

At the core of this cutting-edge technology are biocompatible polymer micropallets that are spin-coated on a glass slide. Figure 1 shows a magnified image of the pallets. These pallets are designed such that cultured live cells remain on the top sur­face of individual pallets, which also can be coated with collagen or fibronectin in order to enhance cell attachment and growth [1]. The use of photo­lithography allows the pallets to be formed with sizes ranging from tens to hundreds of microm­eters. This provides an adequate growth area for single cells or large colonies.

The plasma formation results in the emission of a shock wave and ablation of material within the focal volume, which produces a concur­rent release of the micropallet from the glass slide. The use of these micropallets offers many advantages over other tech­niques such as LCM/LPC [3]:

• No UV laser microdissection step is involved, thereby eliminating potential UV damage to living cells.
• Micropallets are ~50-100 µm in thick­ness, ~ 10-20 x thicker than polymer foils used in LPC. The increased thickness com­bined with the inherent rigidity of the pal­let polymer provides a mechanically stable substrate for living cells to withstand the mechanical stresses of the pallet release process. In addition, this provides a greater insulation of cells against damaging laser thermal effects.
• The release is carried out via micro-pallets that are immersed in growth media at all times, wherein living cells are best nourished.
• The micropallet arrays, with over 20k micropallets (for 100µm micropallet size) on a slide, facilitates process automation since a particular cellular sample can be released by addressing the coordinates of a specific pallet (similar to Tissue Micro-Array or TMA technology).

The development team's primary focus was to design a system that delivers the optimized micropallet release features in a compact, automated, affordable, and easy-to-use package that provides excellent cell viability, without causing any damage to the samples. Further, the iCell system can be mounted on top of any standard industry microscope, independent of the camera, while handling up to eight micropallet slides, or four micropallet Petri dishes containing thousands of micropallets.

The operator selects the cell(s) of interest (see Figure 4), then releases the micropallet using a laser pulse, and collects the cell(s) for further expansion and analysis (shown in Figure 3).

To date, excellent progress has been made in the development of the micropallet laser release system prototype. Our focus will be on testing various commercial applications of the system to ensure that the medical research community can achieve optimal identification and selection of adherent cells.

Looking ahead
Since the NIH's introduction of Laser Microdissection technology in the mid-1990s, the market has evolved at a rate of about 10-15% per year. Currently, other companies have viable Laser Microdissection systems that use somewhat similar techniques for cell selection, but produce the characteristic residual damage to collected cells. Additionally, these systems are priced from about $100,000 up to $500,000, making them cost prohibitive in some laboratory settings.

In addition to a healthy live-cell selection capability, the main driving force for higher penetration in this market in the years ahead will be simplicity and cost efficiency of systems. Industry statistics report approximately 5,000 system placements worldwide. With about 50,000 labs, academic sites and institutes worldwide, the global cell selection market size and potential can be roughly estimated at $5 billion.