Main objectives: 1. Determine whether the POAG patients with low values of the blood mtDNA copy number have a low mtDNA copy number and low mitochondrial function in skin fibroblasts, using in vitro assays of mitochondrial function.2. Explore the…
ID
Source
Brief title
Condition
- Glaucoma and ocular hypertension
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Mitochondrial DNA copy number and mitochondrial function measured in in vitro
assays of skin fibroblasts, compared between control (group 1) and POAG with
low blood mtDNA copy number (group 2).
Correlation between mitochondrial DNA copy number in the blood and
mitochondrial function measured in fibroblasts within the POAG group (group 3).
Secondary outcome
1. Effects of drugs on mitochondrial function as determined in fibroblast
assays.
In case that we can identify POAG patients with lower mitochondrial function
than controls in a fibroblast assay, we will use this in vitro assay to test
whether mitochondrial enforcing drugs can improve mitochondrial function in
these fibroblasts assays. Dose-response curves will be established.
2. Explore the potential value of (additional) blood biomarkers for identifying
POAG patients with mitochondrial dysfunction.
After we have measured mitochondrial dysfunction with the gold standard method
of functional assays in fibroblasts, we can use these data to document the
relation between blood (or blood cell) biomarkers and the status of
mitochondrial function. Besides the blood cell mtDNA copy number which has been
determined before, these biomarkers include blood metabolomics analysis of
metabolites of mitochondrial function (e.g. nicotinamide) and mitochondrial
outer membrane potential measurement in peripheral blood mononuclear cells
(PBMCs) as measured by TMRM staining.
To assess the value of these blood biomarkers, we will calculate the
relationship between the blood biomarker with the mitochondrial parameters
measured in the fibroblast assays.
3. Further characterization of mitochondrial function.
To reveal additional differences between POAG and control subjects, additional
functional assays of mitochondrial function can be performed with the
fibroblasts (e.g. Seahorse XF analysis).
4. Characterization of genetic variants
DNA sequencing will be performed to study the possible association of genetic
variants with mitochondtrial dysfunction and with POAG.
Background summary
Primary Open-Angle Glaucoma (POAG) is a heterogeneous, multifactorial disorder.
Research data increasingly support the hypothesis that, at least in some POAG
patients, suboptimal mitochondrial function plays a role in the
pathophysiology. If we can identify these patients, we can examine whether they
can benefit from drugs that bolster mitochondrial function.
Since taking an optic nerve biopsy to measure local mitochondrial function is
not possible, we tried to measure mitochondrial dysfunction indirectly by blood
biomarkers, such as the blood cell mitochondrial DNa (mtDNA) copy number. This
is a valid strategy since we are looking for genetic predisposition, which
should be apparent in all body cells. Screening for this biomarker revealed
that POAG patients, on average, have lower mtDNA copy number. This lower mtDNA
copy number could mean that the mitochondria are not working well and suggests
that mitochondria may play a role in glaucoma. This is tested in the current
study in which we will use skin fibroblasts to measure mitochondrial function
in detail in a small group of patients, selected based on the level of the
biomarker in their blood. We also want to explore whether this blood biomarker
can be useful for identifying the POAG patients with mitochondrial dysfunction.
Study objective
Main objectives:
1. Determine whether the POAG patients with low values of the blood mtDNA copy
number have a low mtDNA copy number and low mitochondrial function in skin
fibroblasts, using in vitro assays of mitochondrial function.
2. Explore the relation between blood mtDNA copy number and fibroblast
mitochondrial function within the POAG group in order to assess whether the
blood mtDNA copy number could become a diagnostic biomarker identifying POAG
patients with low mitochondrial function within the POAG group.
Secondary objective:
1. If we are able to identify POAG patients with low mtDNA copy number and low
mitochondrial function, we will employ the in vitro assays to screen for
compounds that improve mitochondrial function in vitro in these patients*
fibroblasts.
2. Based on the measurement of mitochondrial function in fibroblasts assays as
*gold standard* method, we will assess additional blood biomarkers for
identifying POAG patients with mitochondrial dysfunction.
3. Further characterization of mitochondrial function using fibroblasts assays
aiming to find additional differences related to POAG.
4. Genetic analysis of mitochondrial genes, especially those involved in mtDNA
replication given the reduced copy number, to identify the underlying genetic
cause or risk factors.
Study design
Mono-center, observational study using biomaterial (skin biopsy, blood).
From each participant, a skin biopsy (3 mm) and a 20 ml fasting, venous blood
will be collected during a single visit to the clinic.
Study burden and risks
Participants will visit the Maastricht UMC only one time. During this visit, we
will collect a skin biopsy (~ 3 mm in diameter) and a (>3 hr) fasting blood
sample (20 ml).
Blood collections and punch skin biopsies are routinely performed in the
clinic. They may be painful in some cases. Infections and bleeding afterwards
are possible, but rare. To minimize patient burden of the skin biopsy, local
anaesthesia will be applied. The burden for the participants is balanced by the
possible benefit to develop neuroprotective treatments for POAG patients with
mitochondrial dysfunction.
P. Debyelaan 25
Maastricht 6229 HX
NL
P. Debyelaan 25
Maastricht 6229 HX
NL
Listed location countries
Age
Inclusion criteria
The source population is the population of the participants of the Eye Tissue
Bank Maastricht (ETBM). The ETBM is open for all glaucoma and cataract patients
of the University Eye Clinic Maastricht to participate. In general, this is an
elderly (glaucoma and cataract), Caucasian population inhabiting the south of
Limburg.
From the population of the ETBM, we previously selected the 175 participants of
the blood biomarker study: POAG patients and controls.
From these 175 participants of the blood biomarker study, we now select 3 study
groups for the current study.
4.2 Inclusion criteria
The blood biomarker study included 175 participants, POAG and Control from the
ETBM with the following criteria:
Inclusion criteria of the biomarker study:
- POAG group: Well-documented diagnosis of POAG.
- Control group: Well-documented ophthalmic history without glaucoma.
- Over 18 years old
Additional inclusion criteria of the current METC research proposal:
- Group 1: POAG patients with lowest values of mtDNA copy number in blood cell
DNA
- Group 2: POAG patients, randomly selected
- Group 3: Control patients, randomly selected; without glaucoma.
We aim to collect fibroblast cell lines from 15 individuals per group. We
expect to need skin biopsies from 15 to max 18 persons per group to achieve
this. We will try to select these from the participants of the previous blood
biomarker study. However, it will not be possible to include sufficient
participants (15 to max 18) from the control group of the blood biomarker study
to reach the required number of 15 individual fibroblast cell lines for the
control group of the current study. To complete the required number for this
group we will include additional control participants who we select directly
(and randomly) from the source population (Eye Tissue Bank Maastricht),
applying all appropriate inclusion and exclusion criteria of this control group
and applying the age range which is present in the other (POAG) study groups of
the current study.
Exclusion criteria
Exclusion criteria of the blood biomarker study:
- Systemic diseases in which mitochondria may be involved.
- Use of drugs that affect mitochondrial function.
Additional exclusion criteria of the current METC research proposal:
- No informed consent
- Use of oral anti-coagulants
- Significant concurrent disease e.g., cancer, diabetes, neurological disorders
(except for glaucomatous disorders), heart-related disorders, blood/platelet
disorders or other diseases affecting the liver, kidney (except kidney stones)
or the lungs (except bronchitis).
- inherited metabolic disorder will be used as exclusion criterium for group 1
and 3, and as variable for group 2
- Other concurrent eye diseases e.g., uveitis, age-related macular degeneration
or diabetic retinopathy.
- Ongoing participation in other clinical trials that contain an intervention.
- Any other factor that in the opinion of the investigator excludes the patient
from the study.
Design
Recruitment
Medical products/devices used
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In other registers
| Register | ID |
|---|---|
| CCMO | NL83466.068.23 |