The Zeiss PALM microdissection system is purchased through the aegis of National Center for Research Resources (NCRR) S10 Shared Instrumentation Grant 1S10RR025624-01, with cost sharing from Feinberg School of Medicine. The PALM system uses a unique combination of high precision microdissection laser and a catapulting pulse of defocused laser to effectively transport the specimen out of the object plane into a collection device, thus allowing user to precisely and gently separate the dissected cells from the rest of the specimen. More importantly, the pressure catapulting mechanism eliminates the necessity of heating any thermoplastic film.

The specimens are usually mounted on a poly ethylene napthalate (PEN) or polyethylene tetraphthalate (PET) membrane. A focused UV microbeam laser performs a locally restricted ablative photodecomposition process without heating the direct environment of the laser beam, thus cutting the tissue. Working with an inverted microscope, these systems are also able to dissect tissue mounted glass slides which might be coated with a PEN membrane.

Using a powerful UV excision laser, the PALM system is perefctly suited for tissue sections up to 200 µm thick, and more importantly for use in conjunction with live cell imaging. Since the ablation microbeam laser can be fine-tuned the widths of 2-3 µm, coupled with the fact that the excision laser cuts through the height of the sample (up to 200 µm), the PALM laser also eliminates the requirement of the dissected sample to overcome any sheer force and cell-substratum force before it can be retrieved, such as the case in mechanical peeling system. It can therefore be used for microdissection at a very high precision. Microdissection of subcellular structures as small as 2 µm can be easily performed.

You can see the instrument in action in the movie below (the movie may take some time to load, depending on your internet connection speed):

The UV laser can also be used to ablate unwanted tissue or to create specific pattern of wound in in vitro wound healing assays.

Subsequent molecular analyses at the protein, DNA and even RNA levels can be performed on the procured specimen. Please consult the appropriate facilities (such as the Genomics Facility) to determine how much sample you will need to harvest for your assay.

To obtain training to use the PALM microdissection system, please contact Dr. Wilson Liu:

(312) 503-1577 or wensheng-liu(at)northwestern.edu