In this model, we perform stereotaxic inoculation of recombinant preformed fibrils (PFFs) into the brains of M83 mice [B6;C3-Tg(Prnp-SNCA*A53T)83Vle/J] or wild-type (B6-C3H) mice.
Our validated injection sites are Striatum +/- Overlying Cortex or Medial Forebrain Bundle (MFB).
The rationale for targeting the Striatum +/- Overlying Cortex includes:
- It is the injection site originally reported by the University of Pennsylvania group (Luk et al., J. Exp. Med., 209: 975-986, 2011; doi: 10.1084/jem.20112457; Luk et al., Science, 338: 949-953, 2012; doi: 10.1126/science.1227157)
- The dopaminergic nerve terminals in the striatum originate from neurons in the substantia nigra
- Injection into the overlying cerebral cortex increases the extent α-synuclein pathology in the brain
Our rationale for targeting the MFB includes:
- It is a tract directly connected to the substantia nigra, which is often used in toxin-based models of Parkinson's disease (e.g. 6-OHDA)
- It serves as a "hub" for projections from many other brain regions, thereby serving as an excellent seeding location to facilitate spreading of α-synuclein pathology to distant brain regions
- This model results in significant loss of dopaminergic neurons in the substantia nigra and associated motor deficits
A significant advantage of this model is the it reproduces many aspects of human Parkinson's disease, including:
- Highly reproducible spreading of α-synuclein in a well-defined spatiotemporal pattern, resulting in extensive α-synuclein pathology in neuronal cell bodies and neurites
- Strong neuroinflammatory component (microgliosis and astrogliosis)
- Neurodegeneration & regional brain atrophy
- Measurable motor function changes
- Amenable to disease modification via therapeutic intervention
A general schema for PFF model generation is:
We have the M83 transgenic mice in-licensed from the University of Pennsylvania. We maintain a well-established breeding colony in-house at Biospective, allowing us to conduct large-scale (>100 mice) studies.
For this specific model, we breed and age M83+/- male mice to 8-12 weeks-of-age. Alternatively, we use wild-type (B6-C3H) mice at 8-12 weeks-of-age. We then perform stereotaxic injection of sonicated, recombinant human α-synuclein PFFs into the target region. We use digital stereotaxic devices with automated microinjectors for high accuracy & precision.
This model is highly reproducible with a nearly 100% success rate of PFF seeding.
Our Validated Measures
- Body weight
- Clinical scores
- Motor function tests
- MRI brain atrophy (Read More in our Presentation - Brain atrophy analysis in rodent models of neurodegenerative diseases)
- Neurofilament Light (NfL) measures in plasma & CSF
- Immunohistochemistry & multiplex immunofluorescence (Read More in our Presentation - Microglial activation in an α-synuclein mouse model of Parkinson's disease)
Learn more about our characterization of this model and our validated measures.
Discover more of our Parkinson's Disease Models
What is the difference between using the M83+/- transgenic compared to wild-type model?
The M83+/- transgenic mice demonstrate a significantly higher level of pathology in a shorter period of time compared to wild-type mice. They also demonstrate a range of progressive changes that can be measured during the in-life phase of the study, including elevated neurofilament light levels in the plasma & CSF, brain atrophy by in vivo MRI, and alterations in motor function, which we do not observe in the milder wild-type mouse model.
Does the α-synuclein fibril seeding model (motor system) show progressive motor dysfunction?
Yes. In particular, the MFB-injection model demonstrates a number of motor deficits typically associated with loss of dopaminergic neurons in the substantia nigra. We have a wide range of motor function tests that are applicable to this model.
Does Biospective perform unilateral or bilateral stereotaxic injections of PFFs?
We can do both. For analysis of spreading, the unilateral injection is ideal as it allows us to assess spread to the contralateral hemisphere. Bilateral injections can be advantageous when a higher level of pathology is desired or when we want equivalence between the brain hemispheres (for example, when one hemisphere will be used for IHC analysis and the other hemisphere for biochemistry analysis).
Can Biospective use human brain extracts/homogenates rather than recombinant PFFs?
Yes, we can do that. Our scientists would be happy to discuss the specifics of this type of model with you.
Is the α-synuclein fibril seeding model (motor system) readily available for studies?
Yes. We maintain a well-established breeding colony of M83 transgenic mice so that mice are readily available for studies. Mice are typically aged to 8-12 weeks prior to inoculation with α-synuclein PFFs.
What is a "preformed fibril" (PFF)?
Recombinant, monomeric proteins (e.g. α-synuclein or tau) are incubated under specific conditions to generate aggregated, misfolded preformed fibrils. These fibrils are then sonicated to generate short fibrils that can be used for in vitro or in vivo studies.