WARNING: This is an ACADEMIC ASSIGNMENT on the Pix Cell II Technique, it is NOT an ADVERTISEMENT!!

Pix Cell II Laser Capture Microdissection System (LCM)

What is Pix Cell II?
    The Pix Cell IITM System increases the accuracy of Laser Capture Microdissection (LCM), so that it can isolate both single cells and large groups of cells for molecular analysis.  Pix Cell IITM allows researchers to isolate subsets of cells from tissue samples and cytological smears.  This technique uses LCM, in which a polymer of laser-activated film is used to isolate a desired population of cells for molecular analysis from a frozen or paraffin embedded tissue selection1. The researcher can then place the film in DNA, RNA, or a buffer to detach their cells from the film, freeing them for molecular analysis.  This technique is used to catalog the progression and development of cells and tissue from health to disease.  LCM is also being used to study pre-malignant cancer lesions, multiple sclerosis, arteriosclerosis, and Alzheimerís disease2.

What is the purpose of microdissection?
    Microdissection is essential when analyzing tissue samples because the desired cells are sometimes only a fraction of the total tissue sample.  Microdissection allows the desired tissue or cells  to be separated from the rest of the sample for molecular analysis.  LCM is a specialized form of microdissection that allows the researcher or pathologist to automatically perform this technique under a microscope by simply pushing a button.  This allows for easier analysis of tissue samples, by isolating them from the surrounding cells, so that the desired tissue can be analyzed to examine changes in gene expressions or cellular DNA that are associated with different transitional stages of certain diseases.  This method allows the researcher to detect the progression of cancer and other diseases without contaminating the rest of the tissue sample3.

                                                   Sample courtesy of Dr. Y.W. Kan, UCSF
                                          (image courtesy of <www.arctur.com/lcm.html >)
Figure 1. Comparison of a blood smear (on left), and a single white blood cell (on right) isolated through Pix Cell IITM and LCM

How is LCM performed?
    LCM uses a laser beam and transfer film to lift the desired cells out of the tissue sample, separating the unwanted cells and tissue from the sample for analysis.  The transparent transfer film is placed on the surface of the tissue sample, and a using a microscope the researcher selects a group of cells.  The researcher uses a joystick to manuever the sample until the desired group of cell is in the center of the field of view.  Once the sample is centered, the operator pushes a button to activate a laser diode in the microscope optics.  The laser diode produces a pulsed laser beam that is directed onto the transfer film directly above the desired cluster of cells.  The laser melts the transfer film, fusing the cells with the film.  When the film is removed from the tissue sample the desired cells are taken with it, leaving behind unwanted tissue sections3.


                                                                         (image courtesy of <www.arctur.com/lcm.html>)
  Figure 2. Procedure for performing LCM

    The Arcturus Engineering, Inc.  system (which manufactures Pix Cell IITM), bonds the transfer film to the underneath of a vial cap placed on the surface of the tissue.  This allows the researcher to be able to see the tissue section through the transparent transfer film when they are using the laser pulse.  (The size of the laser can be adjusted, but it is recommended that it stay within 30 to 60 microns.)   The cells can then be transferred directly from the transfer film to a vial for molecular analysis.  The advantage of this procedure is that the desired cells retain their morphologic features, to insure that the correct cells are being studied.  Computer software, developed by the NIH, stores images of the microdissected cells both before and after LCM has been performed, and serves as a diagnostic record.  LCM can also be used to isolate DNA, RNA, and protein from selected pure cells without damaging their macromolecules. The transfer film is simply put inot a solution containing an enzyme buffer for DNA, RNA, or protein.  This buffer works to detach the desired product away from the transfer film.The tissue section can be fixed in ethanol or formalin, embedded in paraffin, or frozen.  The tissue can also be stained with a variety of stains to easily identify the desired cellsTM.

**Caution: This is not a protocol or procedure for performing LCM!!! For more information or a protocol, click here ***
                        For information on how to prepare tissue  and slides for LCM click here4
                        For some "helpful hints" about LCM click here5

1 Anonymous.  Date Unknown.  Pix Cell II Laser Capture Microdissection System.  <http://www.arctur.com/pxl200.html>  Accessed 1999 Feb 14.
2 Anonymous.  Date Unknown.  Laser Capture Microdissection (LCM).  <http://www.arctur.com/lcm.html>  Accessed 1999 Feb 14.
3 Anonymous.  1998 Oct 15.  Laser Capture Microdissection.  <http://www.ncbi.nlm.nih.gov/nicigap/lcm.html>  Accessed 1999 Feb 14.
4 Anonymous.  1998 Sept 12.  Tissue and Slide Preparation Sample Protocols.  <http://dir.nichd.nih.gov/lcm/LCMATP.htm>   Accessed 1999 Feb 15.
5 Anonymous.  1999 Feb 12.  Helpful Hints.  <http://dir.nih.gov/dirlep/lcm.html#hints>  Accessed 1999 Feb 15.

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