Indposhiv for transplantation
Russian scientists have created the basis for growing human organs
Blog of SIC "Kurchatov Institute", Naked Science
Researchers from the Kurchatov Institute, MIPT and the Institute of Electrophysics and Electric Power Engineering of the Russian Academy of Sciences have developed a method for manufacturing materials with complex geometry from polymer fibers. The method proposed by them can be used to create an analogue of the extracellular matrix in tissue engineering.
The work is described in an article published in Chemical Engineering Journal (Rebrov et al., Enhanced electrospinning: Multi-level fiber alignment by control of electrohydrodynamic jet motion for tissue engineering).
As a basis, the researchers took the method of electrospinning (electroforming), successfully used to produce polymer micro- and nanofibers. Under the influence of a strong electric field, the polymer solution at the tip of the capillary is pulled into a thin fiber that drifts onto the substrate (receiving collector). When deposited, polymer fibers form a ready-made nonwoven fabric.
It can be used to create a "framework" – a kind of "reinforcement" for cellular layers. If the polymer frame created according to an individual project is "populated" with the patient's stem cells, then in this way it is possible to "grow" an organ that is ideal for transplantation.
However, in order to reproduce the structure of an organ, a very complex architecture of the material is often required, reproducing the morphology of native tissues. For example, in the inner shell of the wall of a blood vessel, the fibers are directed parallel to the blood flow, and in the middle — in a circle. This is required to ensure the strength of the vessel during the movement of the pulse wave of blood, in this case, the stretching forces are directed in different directions.
Thus, the directed growth of cell cultures requires a complexly ordered morphology of the polymer framework. To realize this idea, it is necessary to control the orientation and laying of each fiber. The authors of the article proposed to do this by controlling the position of the electrohydrodynamic polymer jet during the drift towards the collector.
"Now there are four electrodes in our design on the substrate," explains Ksenia Lukanina, head of the Department of nanobiomaterials and Structures of the Kurchatov complex of NBICS–nature–like technologies. – We can control the orientation of the fiber layers, up to the monolayer. By increasing the number of electrodes, changing their location, it is possible to set more and more complex geometry, literally controlling the position of each fiber."
In the near future – volumetric polymer structures. "Combining mechanical rotation and the method of controlled fiber deposition proposed by us, we are able to create hyperboloid structures, like the Shukhov Tower, or cylindrical frames with fibers laid perpendicular and along," said Igor Rebrov, head of the Laboratory of Electrohydrodynamic Systems.
In addition, scientists have proposed a solution for the production limitation of the classical electrospinning method, which consists in the limited thickness of the non-woven fabric. When a sufficient amount of charged fibers accumulates on the collector, the deposition of new ones stops, since there is no potential difference that would cause the polymer to attract.
The researchers added to the design of the installation the ability to change the polarity of the applied electric field, so the charge of the fibers can be reversed. Now the fibers and the collector are charged differently again, and the process can be continued. Thus, it is also possible to obtain oriented fibers on dielectric surfaces, which significantly expands the capabilities of the method.
"Our technology occupies a niche between the classical method, when the material is produced quickly, but without orderly laying of fibers, and 3D printing by the method of stabilized electrospinning - in this case, printing takes place fiber–by–fiber, but extremely slowly," explained Timofey Grigoriev, Deputy Director of NBICS-pt for scientific work.
A new approach to electrospinning will allow obtaining more complex nature-like polymer structures for tissue engineering. Perhaps, over time, polymer matrices created on an "individual order", populated with stem cells of the patient himself, will solve the problem of a shortage of donor organs and get rid of the negative effects associated with imperfect compatibility.
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