Figure 1: Top: 3D reconstruction of 3D brain microvessels. Bottom: Ultrastructural imaging showing multiple P. falciparum-iRBCs binding to a primary human brain microvascular endothelial cell (EC) within the 3D brain microvessels. The major focus of the lab is to understand how P. falciparum mediates brain vascular damage.
Video 1: Perfusion of P. falciparum-iRBCs within the 3D brain microvessels. (WSS: Wall Shear Stress)
The Bernabeu group aims to understand the mechanisms that lead to vascular dysfunction in cerebral malaria by developing new in vitro models of the human blood–brain barrier.
Previous and current research
Blood–brain barrier in health
The blood–brain barrier (BBB) plays a key role in maintaining neural function, as it prevents the entry of toxins and infectious agents into the brain parenchyma. The highly specialised function of the BBB is accomplished by endothelial tight junctions and selective transport that provide refined control of the paracellular and transcellular permeability. Pericyte and astrocyte signalling contributes to a significant increase in the barrier properties of endothelial cells. Our lab is developing an in vitro 3D brain microvascular model that better recapitulates the human BBB vascular 3D structure and function. Our studies will focus on the role that perivascular cells, vascular geometry, and flow characteristics play in vessel integrity and function.
Blood–brain barrier in disease: cerebral malaria
BBB disruption has been associated with multiple severe diseases, including stroke, epilepsy, multiple sclerosis, bacterial sepsis, haemorrhagic fevers, and malaria. Plasmodium spp. cause around 200 million new malaria infections and half a million deaths every year. Among the multiple severe complications that malaria patients can suffer, cerebral malaria is one of the deadliest.
One of the key pathogenic features of cerebral malaria is adhesion of Plasmodium falciparum-infected red blood cells (iRBCs) in the brain microvasculature. Parasite sequestration prevents parasitic clearance by the spleen, but it can have severe consequences when multiple infected red blood cells sequester in organs with a critical function, such as the brain. Plasmodium falciparum-iRBCs bind to multiple endothelial receptors. By using machine learning approaches, we have recently shown that parasites that bind endothelial protein C receptor (EPCR) and intercellular adhesion molecule 1 (ICAM-1) are expanded in the peripheral blood of patients with cerebral malaria. However, we do not yet have a clear understanding of what happens in the brains of these patients.
The P. falciparum parasite is species-specific to humans, and thus cannot be studied in model species. 3D culture of human tissues is therefore an exciting approach to tackling this question. We have recently developed an endothelial-only 3D brain microvessel model (Figure 1), in which infected cells can be perfused through the in vitro vasculature. Our work has shown that P. falciparum-iRBCs present high sequestration levels within 3D brain microvessels, and has provided new information on host–parasite interactions (see figure 1 and video 1).
Future projects and goals
Our lab uses a combination of bioengineering, computational and experimental tools to better understand cerebral malaria pathogenesis. By developing an in vitro 3D human blood–brain barrier model with primary or iPSC-differentiated cells, we aim to understand how parasite and host factors interact to cause endothelial and perivascular damage. With this system, we will model the pathogenic mechanisms and signalling pathways that lead to BBB breakdown in patients with cerebral malaria.