Capillary model tracks blood flow in healthy and diseased networks

The human circulatory system is a complicated place, but nowhere is it more convoluted than in capillary networks. Capillaries, the smallest blood vessels, form an interwoven mesh through which blood cells must squeeze through in single file. The dynamics of this flow, especially when including suspended cells, are complex and not well understood. In particular, when the flow paths suddenly change in the event of a constriction or blockage in one capillary, the response of blood cells is difficult to predict.

Ostalowski and Tan developed a 3D simulation of blood flow inside a capillary network to answer questions about how blood cells behave in these networks. The full 3D network was reconstructed from a model based on 2D patient retina scans.

The researchers identified several unique behaviors in their model. For instance, they observed cell accumulation at three-way junctions, reduced flow with the introduction of large white blood cells, and altered flow when one vessel was blocked or constricted.

“What is interesting is that with some degree of constriction in one vessel, some blood cells can be trapped in another vessel, e.g, moving back and forth in the trapped vessel,” said author Jifu Tan. “This oscillating behavior may be responsible for certain diseases in the retina such as blindness.”

The pair hopes their study will influence the diagnosis or treatment of disease.

“We are planning to collaborate with experimental scientists to study eye diseases, such as diabetes induced blindness,” said Tan. “I would be very happy if our simulation results could be used to design or guide experiments.”

Source: “Direct simulation of blood flow with heterogeneous cell suspensions in a patient-specific capillary network,” by Kacper Ostalowski and Jifu Tan, Physics of Fluids (2022). The article can be accessed at https://doi.org/10.1063/5.0088342 .