Contributions
Abstract: 139
Type: Oral
Abstract Category: Therapy - disease modifying - Neuroprotection
The potential of mesenchymal stromal cell (MSC) therapy for progressive multiple sclerosis (MS) is being investigated. Previously, we have shown that MSCs from patients with MS have reduced proliferative and neuroglial protective properties in vitro. Given that the MSC secretome - the collective term for factors secreted as soluble molecules and/or in extracellular vesicles - is known to have trophic and neuroglial protective effects, we compared media conditioned by MSCs isolated from control subjects (MSCcm) and those with progressive MS (MS MSCcm).
Using tandem mass spectrometry of age-matched samples, we observed a relative reduction in the concentration of mitochondrial fumarate hydratase (mFH) in MS MSCcm. mFH has an extended N-terminal and is the only isoform of fumarate hydratase expressed in brain and catalyzes hydration of fumaric acid to L-malic acid in the citric acid cycle. Dimethyl fumarate is a fumaric acid ester used to treat relapsing-remitting MS.
The unexpected finding of reduced mFH in MS MSCcm was confirmed by ELISA and reduced expression of mFH by MS MSCs was detected using western blot analysis. Addition of recombinant mFH to media conditioned by MS MSCs abrogated deficits in MS MSCcm-mediated neuroglial protection in vitro and led to increased MS MSC expression of nuclear related (erythroid-derived 2)-factor 2 (Nrf2) which is known to mediate cell responses to oxidative stress and neuroprotective effects of fumaric acid esters.
Our findings suggest that reduced expression of mFH contributes to impaired neuroglial protection mediated by MS MSCcm under conditions of oxidative stress in vitro. This raises the possibility that low levels of endogenous mFH in MS may be a potential biomarker for progressive disease. The finding is not incompatible with use of dimethyl fumarate to treat MS as fumarase activity will, at least initially, increase with the concentration of substrate via saturation kinetics.
Future work will examine activity of the known mFH target hypoxia-inducible factor-1a as well as interrogation of Nrf2 activation pathways. We will determine whether there are alterations in sub-cellular localisation of fumarase hydratase in MS, measure levels of fumarase activity and investigate whether modulation of fumarase activity alters predisposition to disease in models of demyelination. We will also explore whether reduced levels of mFH in MS MSCcm reflects a fundamental deficit in cellular transfer of mitochondria in MS.
Disclosure:
P.Sarkar- nothing to disclose.
J.Redondo- nothing to disclose.
K.Kemp- nothing to disclose.
A.Wilkins- nothing to disclose.
NJ.Scolding- nothing to disclose.
C.M.Rice- nothing to disclose.
Source of Funding for all authors: Burden Neurological Institute.
Abstract: 139
Type: Oral
Abstract Category: Therapy - disease modifying - Neuroprotection
The potential of mesenchymal stromal cell (MSC) therapy for progressive multiple sclerosis (MS) is being investigated. Previously, we have shown that MSCs from patients with MS have reduced proliferative and neuroglial protective properties in vitro. Given that the MSC secretome - the collective term for factors secreted as soluble molecules and/or in extracellular vesicles - is known to have trophic and neuroglial protective effects, we compared media conditioned by MSCs isolated from control subjects (MSCcm) and those with progressive MS (MS MSCcm).
Using tandem mass spectrometry of age-matched samples, we observed a relative reduction in the concentration of mitochondrial fumarate hydratase (mFH) in MS MSCcm. mFH has an extended N-terminal and is the only isoform of fumarate hydratase expressed in brain and catalyzes hydration of fumaric acid to L-malic acid in the citric acid cycle. Dimethyl fumarate is a fumaric acid ester used to treat relapsing-remitting MS.
The unexpected finding of reduced mFH in MS MSCcm was confirmed by ELISA and reduced expression of mFH by MS MSCs was detected using western blot analysis. Addition of recombinant mFH to media conditioned by MS MSCs abrogated deficits in MS MSCcm-mediated neuroglial protection in vitro and led to increased MS MSC expression of nuclear related (erythroid-derived 2)-factor 2 (Nrf2) which is known to mediate cell responses to oxidative stress and neuroprotective effects of fumaric acid esters.
Our findings suggest that reduced expression of mFH contributes to impaired neuroglial protection mediated by MS MSCcm under conditions of oxidative stress in vitro. This raises the possibility that low levels of endogenous mFH in MS may be a potential biomarker for progressive disease. The finding is not incompatible with use of dimethyl fumarate to treat MS as fumarase activity will, at least initially, increase with the concentration of substrate via saturation kinetics.
Future work will examine activity of the known mFH target hypoxia-inducible factor-1a as well as interrogation of Nrf2 activation pathways. We will determine whether there are alterations in sub-cellular localisation of fumarase hydratase in MS, measure levels of fumarase activity and investigate whether modulation of fumarase activity alters predisposition to disease in models of demyelination. We will also explore whether reduced levels of mFH in MS MSCcm reflects a fundamental deficit in cellular transfer of mitochondria in MS.
Disclosure:
P.Sarkar- nothing to disclose.
J.Redondo- nothing to disclose.
K.Kemp- nothing to disclose.
A.Wilkins- nothing to disclose.
NJ.Scolding- nothing to disclose.
C.M.Rice- nothing to disclose.
Source of Funding for all authors: Burden Neurological Institute.