Incremental Improvement in Kidney Tissue Engineering

One small step at a time, researchers continue to improve in their attempts to build patient-matched organs for transplantation. An organ constructed with the patient's own cells should have a much lower chance of transplant rejection, and greater odds of success overall. Here work focuses on assembling the necessary techniques to make xenotransplantation feasible:

"Until now, lab-built kidneys have been rodent-sized and have functioned for only one or two hours after transplantation because blood clots developed. In our proof-of-concept study, the vessels in a human-sized pig kidney remained open during a four-hour testing period. We are now conducting a longer-term study to determine how long flow can be maintained." If proven successful, the new method to more effectively coat the vessels with cells (endothelial) that keep blood flowing smoothly, could potentially be applied to other complex organs that scientists are working to engineer, including the liver and pancreas.

The current research is part of a long-term project to use pig kidneys to make support structures known as "scaffolds" that could potentially be used to build replacement kidneys for human patients with end-stage renal disease. Scientists first remove all animal cells from the organ - leaving only the organ structure or "skeleton." A patient's own cells would then be placed in the scaffold, making an organ that the patient theoretically would not reject.

The cell removal process leaves behind an intact network of blood vessels that can potentially supply the new organ with oxygen. However, scientists working to repopulate kidney scaffolds with cells have had problems coating the vessels and severe clotting has generally occurred within a few hours after transplantation.

The [scientists] took a two-pronged approach to address this problem. First, they evaluated four different methods of introducing new cells into the main vessels of the kidney scaffold. They found that a combination of infusing cells with a syringe, followed by a period of pumping cells through the vessels at increasing flow rates, was most effective. Next, the research team coated the scaffold's vessels with an antibody designed to make them more "sticky" and to bind endothelial cells. Laboratory and imaging studies - as well as tests of blood flow in the lab - showed that cell coverage of the vessels was sufficient to support blood flow through the entire kidney scaffold.

Link: http://www.eurekalert.org/pub_releases/2014-09/wfbm-mri090814.php

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