Laser microdissection and DNA typing of cells from single hair follicles.

Isolation and identification of single cells from tissue samples or smears assume a great relevance in pathological and forensic applications; in this latter field, the possibility to identify a specific genetic profile can be obtained by short tandem repeat (STR) typing, allowing to achieve a scientific proof important in law courts. It is well known that DNA extraction may be performed from several tissue fragments, blood traces, spermatozoa as well as telogen hair. However, in the last case, few follicle cells are coupled to a great amount of keratin reducing the efficiency of DNA amplification. Recently, the introduction of laser microdissection technique has greatly improved the capability to select single cells without any cross-contamination. In the present report, we have performed a laser microdissection using a Leica AS LMD (Leica Microsystems, Germany), utilized on cutting the telogen hair in order to exclusively collect the lower part of the follicle and reduce keratin contamination. In this way we can accurately extract an adequate amount of DNA, successfully typed by STR profile.