At BrainPlotting we use fresh Human brain tissues to make our predictions. We are specialized in in vitro culture of cells issued from Human brains. In our catalogue we offer high performance tools as close as possible to the Human situation.
I. Blood brain barrier models
We propose reliable and characterized tools to determine the permeability of specific compounds trough the BBB: from blood to brain; as well as from brain parenchyma to blood. Our tools and technologies result from more than 15 years of research and development conducted with several academics as well as private companies.
After capillaries have been gently isolated from brain tissue, brain endothelial cells are purified and amplified before passing in specific inserts of culture. They are grown and they differentiate for a few days before experimentations are done in the best conditions.
II. Determination of the unbound fraction (fu) in the blood and in the brain parenchyma
The unbound fraction of a compound is its active and functional concentration. It is the fraction that can interact with its environment and then cross biological membranes and activate pharmacological targets. Blood and brain unbound fractions are not correlated and can differ a lot from a compound to another depending of the pharmacokinetic compartment considered.
In the blood, we use fresh human plasma to determine the unbound fraction in vitro as a model to what happens in the Human body.
In the brain parenchyma, we have two different and complementary approaches:
1 Determination of the unbound fraction in Human brain homogenate
The compound is mixed with brain tissue homogenate obtained by sonication and rich with protein and lipid mix specific to the Human brain. The fraction left unbound to the brain homogenate mix is the fraction which will potentially cross BBB membranes and potentially interact with pharma-active targets. This data can be compared with the plasma unbound fraction.
2. Determination of the unbound fraction in fresh Human brain slices
The compound is exposed to thin slices of living brain tissue until equilibrium. The unbound concentrations in brain cells and in the extracellular fluid (interstitial fluid) is then determined. In this situation where the BBB is bypassed, the behavior of the compound inside the brain parenchyma can be determined. Also, specific transport mechanisms can be studied with this tool.
All these data can be combined with PBPK approaches to model the Human in vivo concentrations on the basis of Human in vitro data.