HomeUnderstanding PANDAS and PANS | A Comprehensive Resource GuidePANDAS StoriesPANDAS Network $50K Grant is Used to Fund a New Stem Cell Model to Accelerate PANDAS/PANS Research

PANDAS Network $50K Grant is Used to Fund a New Stem Cell Model to Accelerate PANDAS/PANS Research

Generous donations to the PANDAS Network in the amount of $50,000 from the 2023 Research Fund was awarded to Dr. Irene Munk Pedersen for her exciting PANDAS/PANS research.

Her laboratory developed a way to model the human blood-brain barrier (BBB) in 3D by converting human skin cells into stem cells. These stem cells are grown into human brain blood vessel tubes, which behave like blood vessels in the brain.

The PANDAS Network grant will allow Dr. Pedersen’s team to discover which genetic mutations in PANDAS patients are involved in PANDAS/PANS disease progression (this model simulates the brain of children with PANDAS). For past donors please recall that we have two other grants out pending publication in 2024-2025.

But first, let’s learn what the blood-brain barrier is and why it is important for keeping our brain healthy.

What is the Blood-Brain Barrier (BBB)?

Endothelial cells form the tube-like structure of blood vessels. Certain tissues like the liver, kidneys, and small intestine have specialized blood vessels that contain large gaps between the borders of the endothelial cells. This allows for molecules to easily exit the blood vessel.

The brain’s blood vessels are different. The borders of endothelial cells in the brain are tightly zipped, preventing harmful substances and cells from entering the brain. However, the stability of the BBB is regulated by more than endothelial cell ‘zippers’ called tight junctions. The following cells also contribute to the BBB stability in the following ways:

  • Astrocytes – wrap their “feet” around blood vessels
  • Pericytes – surround the vessel providing structural support
  • Extracellular Matrix (ECM) – the ECM is not a layer of cells but a scaffold of proteins that provide structural support to the blood vessel (pictured below in white)

The Neurovascular Unit Supports the Barrier Function of the BBB

Diagram of the various cell types that collectively form the neurovascular unit

Together these three cell types (endothelial cells, pericytes, astrocytes) and the ECM form a structural unit called the neurovascular unit (NVU). The NVU helps form the barrier that keeps harmful substances out of the brain.

Think of the BBB as a fortified castle wall while the neurovascular unit is the castle itself. Behind the castle wall (BBB), there is a community of supporters actively patching any cracks that might suddenly appear (astrocytes and pericytes) and ensuring the support beams are structurally sound (ECM).

Dr. Pedersen’s 3D stem cell models the “cellular castle” (NVU) not just the castle wall (BBB). This makes Dr. Pedersen’s 3D stem cell model a robust tool for answering important PANDAS research questions that have historically been difficult to answer.

Genetic Differences In PANDAS Patients Are Identified

Dr. Pedersen’s collaborator, Dr. Dritan Agalliu, discovered that subgroups of PANDAS patients have key differences in the DNA sequences of genes predicted to impact the brain.

Dr. Pedersen’s 3D stem cell model of brain blood vessels will be used to discover if any of these PANDAS genes make blood vessels in the brain more leaky. This is an important question to answer because PANDAS patients often suffer from neuroinflammation facilitated by the entry of immune cells and cytokines past the blood-brain barrier.

How Are Brain Blood Vessels Grown in a Dish?

Dr. Pedersen’s team uses specialized cell culture plates that act as a mold needed to encourage the formation of brain blood vessels and the supporting cells. To visualize the vessels, fluorescently labeled antibodies are used to label endothelial cells (green), pericytes (purple), and astrocytes (red).

The image above shows that endothelial cells are coalescing into a vessel and the supporting cells (pericytes and astrocytes) localize to the same regions they would in the brain. Specifically, the pericytes (purple) cover the outside of the blood vessel, and the astrocytes interact with the blood vessel cells shown by the yellow staining (yellow indicates red and green overlap). But, are the vessels impenetrable similar to the ‘castle fortress’-like vessels found in the brain?

Do The Blood Vessels in a Dish Behave like Blood Vessels in the Brain?

To answer this, Dr. Pedersen’s team added a green tracer inside the blood vessel and measured how much dye leaked out. We would predict no tracer would leak out if the vessels function similarly to vessels in the brain (because of the BBB).

As predicted, the vessels not only structurally look like vessels in the brain, but they also have a robust barrier preventing molecules from leaking past the vessel wall. This can be visualized by comparing the amount of green tracer when no cells are present (far left bar) compared to the amount of tracer leakage when cells are present (‘no sera’ bar).

The image depicts the green tracer (green balls) being added to the vessel. The amount of leakage (white arrow) is measured

PANDAS Sera Makes Brain Blood Vessels More Leaky.

The brain blood vessels grown on a dish have barrier qualities, but does adding PANDAS sera, the liquid portion of blood, to the vessels make them more leaky?

To answer this question, Dr. Pedersen’s team added PANDAS sera (patient sera – black bar) to the blood vessel tubes for 24 hours followed by measuring the amount of green dye that leaked past the vessel wall. When compared to sera from healthy volunteers (control sera – grey bar), the amount of green tracer leaking past the blood vessel is significantly more than that from healthy volunteers.

Click below to learn more scientific details about Dr. Pedersen’s 3D stem cell model.

Dr. Pedersen’s Future Research Objectives

Dr. Pedersen will utilize the PANDAS Network grant to introduce PANDAS genes into stem cells destined to differentiate into endothelial cells, pericytes, astrocytes, and white blood cells circulating in the bloodstream. This initiative aims to discern the potential role of these genes in the development of blood vessel leakiness. These experiments will help her team understand which genetic factors and immune responses impact the brain’s protective barrier and overall function.

Their goal is to gain valuable insights into how these factors contribute to the characteristics of PANDAS, paving the way for potential future treatments or interventions.

The PANDAS Network is grateful for the support of our amazing donors. Your generosity is accelerating this transformative research!