gms | German Medical Science

Objectives: Tissue engineering is an emerging field to replace damaged or resected areas, especially in the musculoskeletal system. Recently, two strategies are followed to create new 3D tissues: A) Manufacturing of an artificial scaffold that serves as a primary structure to where cells can bind, and B) manufacturing of scaffolds from decellularized biological tissue that only consist of the extracellular structure without any earlier DNA content. In this study we'll focus on 3D-scaffolds, created by decellularizing biological tissue using a new designed and automatically controlled perfusion system.

Methods: Within this study we designed an automated device to simultaneously decellularize four rat kidneys (Figure 1 [Fig. 1]). As reported by the literature we were using sodium dodecyl sulfate (SDS), distilled water (dH2O) and an antibiotic mix for final sterilization (Penicillin and Streptomycin). Three magnetic squeeze valves are used to release or block fluid flow from each liquid container, all controlled by a computer-based user interface and a USB-connected relay circuit. After passing the valves the three tubes are connected together and run into a pressure controlled peristaltic pump. The two functions of the pump are i) to pump the medium to a container for further fluid distribution and ii) to measure the pressure at the outlet of the peristaltic pump to guarantee that the selected pressure is applied. In this application the pressure that will be used to perfuse the kidneys is set to 100 mmHg and the maximum rotational speed of the peristaltic pump is limited to 20% of the maximum motor speed. Finally, the pressurized tube leads to a pressurized container with a bubble trap on top and four outlets on the bottom to perfuse 1-4 kidneys via its Arteria renalis. All liquids that are pumped into the kidney leave the tissue by perfusion through the Vena renalis or by diffusing though the kidneys outer surface (Capsula fibrosa renalis). Used liquid is then collected in a container and can either be recycled or disposed.

Results and Conclusion: First tests showed a highly reliable use of the system. None of the kidneys was destroyed by over-pressurization or leading air bubbles into the Arteria renalis. The user interface was realized as a step-by-step, tab-based program that automatically disables the buttons that are not part of the current configuration step. All components that are in contact with the liquids can be autoclaved, except of the tubing of the peristaltic pump which is a sterile disposable. Because of this advantage, the system can also be used as a bioreactor for recellularization of perfused tissues in the near future.