Our kidneys are designed to filter out all kinds of impurities from the blood stream, a process that’s not particularly selective. This is done by glomeruli, which are groups of capillaries at the end of kidney tubules. But other parts of the kidneys, the proximal tubules, are charged with returning wanted nutrients back into the body. When the glomeruli and proximal tubules work well together, filtration and selective re-absorption ensure the purity and essence of our natural fluids.

Shown with cellular resolution, cells in both the proximal tubule epithelial channel (red) and the vascular channel (green) have mature typical morphologies and seamlessly cover their respective channel surfaces to form a proximal tubule and blood vessel.

While poor filtration is one kind of problem that kidneys can exhibit, failure to reabsorb nutrients is another. Studying how proximal tubules fail on a cellular level is a complicated science, normally requiring animal studies. Researchers at Harvard’s Wyss Institute and Roche Innovation Center Basel in Switzerland have now developed a vascularized model that closely mimics natural proximal tubules.

The technology mimics the re-absorptive properties of the proximal tubules and it can be used to test various drugs and other therapies in order to evaluate how they would perform in a real kidney. The tubules and accompanying blood vessels are 3D printed right next to each other inside an extracellular matrix. This is a big leap over previous research that led to the development of the proximal tubules, but without the matching blood vessels. The new development allows experiments to be conducted that closely replicate natural kidney functions.

The team already used their technology to study how glucose is transported from the proximal tubules into the blood vessels and how hyperglycemia, a common diabetes-related condition, can wreak havoc on the kidneys.

“We construct these living renal devices in a few days and they can remain stable and functional for months,” in a press release said Neil Lin, Ph.D., one of the study leads. “Importantly, these 3D vascularized proximal tubules exhibit the desired epithelial and endothelial cell morphologies and luminal architectures, as well as the expression and correct localization of key structural and transport proteins, and factors that allow the tubular and vascular compartments to communicate with each other.”

Here are a couple videos that show the printing and functionality of the new kidney mimics:

Top image: Immunofluorescence staining of a 3D bioprinted vascularized proximal tubule with a proximal tubule epithelial marker stained in green in the proximal tubule channel and a vascular endothelial marker stained in red in the adjacent vascular channel. The magnified cross-section illustrates that the two different cell types form luminal perfusable structures in their respective channels.

Flashback: Scientists Use 3D Printers to Recreate Kidney’s Proximal Tubules…

Study in Proceedings of the National Academy of Sciences: Renal reabsorption in 3D vascularized proximal tubule models…

Via: Wyss Institute…



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