Dr. Benoit Gentil 2024 Report
Principal investigator responsible of the project: Dr Benoit J Gentil
Personnel involved :
– Nancy Larochelle, Research
Associate
– Sandra Minotti, technician
– Zacharie Cheng-Boivin, Graduate student
– Alexandre Paré, Graduate student
– Caitlin Atkinson, Graduate student
– Ryan Dvorak, Undergraduate student
Future directions of Dr Gentil and his team include the identification of therapeutic approaches for CMT1A. They use cellular models to screen and assess the efficiency of their
different strategies. At the moment, Dr Gentil is collaborating with Dr Gunning (Gunning Group | Patrick Gunning) who developed new HDAC inhibitors to test their therapeutic potential for CMT. He proposed to add a model of CMT1A to test the potential of this HDAC and to characterize the
therapeutic potential of HDAC inhibitors in CMT1A.
Results to date: Dr Gentil and his team have tested the dose effect of 3 molecules made by Dr Gunning’lab having potential for HDAC inhibitors and showed that they induce acetylation of tubulin in spinal cord cultures in-vitro. They used the optimal dose to test its effect on sensory neurons Schwann cell co-
culture which were induced to differentiate with vitamin C and demonstrated their efficiency
in regulating myelin protein expression. The molecules have a positive effect on myelination
which opens the path to testing their efficiency in CMT1A cellular models.
Perspectives/future plans: The aim is to model CMT1A in vitro by transdifferentiating fibroblasts derived from patients’
skin biopsies carrying mutations in CMT1A. The goal is to evaluate the efficacy and safety of
three HDAC inhibitors on axon myelination by Schwann cells, which will be transdifferentiated
from patient-derived fibroblasts and co-cultured with sensory neurons. Functional Schwann
cells will be generated using somatic cell reprogramming procedures as described by Sowa et
al. This involves transducing SOX10 and Krox20 genes into fibroblasts Direct Conversion of
Human Fibroblasts into Schwann Cells that Facilitate Regeneration of Injured Peripheral Nerve
In Vivo – PubMed (nih.gov). Models using fibroblasts derived from patients affected by CMT1A
will be treated with the HDAC inhibitors. Resorption of abnormal myelination by HDAC
inhibitors will indicate their potential for therapeutic use. Should the results be positive, they will
proceed to test these inhibitors in animal models.
Training of talents: HNF Canada contributed to the professional development of Dr Gentil’s students,
Zacharie Cheng-Boivin (Ph.D. candidate), Alexandre Paré (PhD. candidate), and Caitlin
Atkinson (MSc candidate) from the Kinesiology graduate program of McGill University. In
addition, the CMT project provided laboratory experience to several undergraduate students
enrolled in the Kinesiology honors program.
Dr. Benoit Gentil 2023 Report
Principal investigator responsible of the project: Benoit J Gentil
Personnel involved:
– Sandra Minnotti, technician,
– Zacharie Cheng-Boivin, Graduate student
– Alexandre Paré, Graduate student
– Genevieve McKay, undergraduate student
– Sami Azhari, undergraduate student
– Eric Lucas, undergraduate student
– Robin Dagher, undergraduate student
Results to date: In May 2022, Dr. Gentil reported that their attempts to develop a Zebrafish model
overexpressing the gene responsible for CMT1A, PMP22, was unsuccessful because the gene
sequence of PMP22 and the cDNA at his disposal was not functional. Since then, this technical
difficulty has yet to be solved, and he cannot generate a cDNA sequence expressing PMP22. Dr.
Gentil’s laboratory could not leverage the funding to generate cellular models derived from patients
called IPSC. His laboratory then focused on identifying therapeutic opportunities, and took
advantage of their ARSACS program. They are developing active peptides efficient in resorbing
aggregates of abnormal proteins like PMP22. Their active peptides did not co-localize with PMP22
and did not resorb aggregates of PMP22, characteristic of CMT1A. Proteomic analysis of the partners of their peptides did not identify PMP22, indicating that PMP22 is not a target of their peptides and that this strategy is unlikely to be translated in CMT1A.
Training of talents: HNF Canada’s support has contributed to the professional development of Dr Gentile’s students,
Zacharie Cheng-Boivin (Ph.D. candidate) and Alexandre Paré (M.Sc. candidate), the Kinesiology
and Integrated Program of Neuroscience of McGill University. In addition, the CMT project
provided laboratory experience to several undergraduate students enrolled in the Kinesiology
honors program.
Awareness strategy: Dr Gentile’s group has an active program on CMT and is committed to developing
therapeutic strategies and moving the field forward. They welcome undergraduate students during
their honor project, which contributes to raising awareness about CMT amongst some of their most promising
students. Several of these students have been enrolled in medicine, physiotherapy, or pharmacy,
which will bring more awareness toward CMT and future allies in disciplines in contact with
patients affected by inherited peripheral neuropathies. In addition, in the context of his course
EDKP449 (Exercise Physiopathology), Dr. Gentil lectures CMT and other neuromuscular
disorders to train future kinesiologists.
Perspectives: Although Dr. Gentil’s lab faced some set back in the original plan, their laboratory
still plans to study CMT1A by adding this model to the different relevant strategies developed for
other diseases studied on the laboratory. As such, they have a collaboration with Dr. Gunning
(Gunning Group | Patrick Gunning) aiming to test the therapeutic potential of a new Histone
Deacetylase (HDAC) inhibitor developed in his laboratory. HDAC inhibitors have been shown to
be efficient in resorbing cellular abnormalities of axonal forms of CMT. HDAC inhibitor, like
suberoylanilide hydroxamic acid (SAHA), has been shown to increase myelin thickness and
improve nerve conduction velocities in mouse models of CMT1A.
In 2021 we donated funds to Dr Gentils’ research lab at McGill University. His laboratory is setting up a research program aiming to:
1) Develop cellular models derived from patients (i.e., iPSc-derived Schwann cells) in order to have a better understanding of the molecular mechanism involving a specific mutation or overabundance of PMP22. Considering the large number of different mutations causing CMT1A, this will be key to develop mechanism-based therapeutic approaches tailored to patients, and;
2) Identify therapeutic opportunities in this model by characterizing the RNA profile of Schwann cells carrying triplication or mutations of PMP22 and;
3) Develop a zebrafish model of CMT1A over-expressing PMP22 in order characterize the pathogenesis and more importantly to provide an animal model for rapid drug testing. The generation of these models are an important step to characterize the pathogenesis and identify therapeutic approaches based on molecular mechanisms.
Promising Research and Past Accomplishments
One promising area of research involves gene therapy experiments. Research with cell cultures and animal models has shown that it is possible to deliver genes to Schwann cells and muscle. Another area of research involves the use of trophic factors or nerve growth factors, such as the hormone androgen, to prevent nerve degeneration. Vitamin C has been studied in CMT1A and the results of a multi-centric trial are due soon.
To date our gifts have helped with promising CMT research undertaken through the University of Florida and the University of Southern California. These potential therapies are all in the early stages, and have not yet been studied in humans. However, they offer hope for the future.