  Krabbe disease (KD) is a rare demyelinating sphingolipidosis, often fatal in
the first years of life. It is caused by the inactivation of the
galactocerebrosidase (GALC) enzyme that causes an increase in the cellular
levels of psychosine considered to be at the origin of the tissue-level
effects. GALC is inactivated also in the Twitcher (TWI) mouse: a genetic model
of KD that is providing important insights into the understating of the
pathogenetic process and the development of possible treatments. In this
article an innovative optical technique, RP-CARS, is proposed as a tool to
study the degree of order of the CH2 bonds inside the myelin sheaths of
TWI-mice sciatic-nerve fibres. RP-CARS, a recently developed variation of CARS
microscopy, is able to combine the intrinsic chemical selectivity of CARS
microscopy with molecular-bond-spatial-orientation sensibility. This is the
first time RP-CARS is applied to the study of a genetic model of a pathology,
leading to the demonstration of a post-onset progressive spatial
disorganization of the myelin CH2 bonds. The presented result could be of great
interest for a deeper understanding of the pathogenic mechanisms underlying the
human KD and, moreover, it is an additional proof of the experimental validity
of this microscopy technique.
