3D Printer Leather

3D Printer on Arduino Prints Functional Human Skin

Anatoly Alizar, Geektimes
(for links to sources, see the original article)

According to WHO estimates, every year about 11 million patients in the world need skin grafts after burns, and 265 thousand victims have skin lesions so extensive that they lead to death. Skin transplantation is also required as a result of various pathologies, infections, after operations to remove cancerous tumors, due to genetic and somatic diseases.

Autogenous grafts are usually used to restore the skin, when a skin area is taken from the recipient himself. Unfortunately, with a large area of burns, it may be impossible to find suitable areas in sufficient quantity.

Doctors are trying to research different technologies to obtain a suitable substitute, but so far the results are far from ideal. The results are unreliable: the material turns out to be too fragile, it is difficult to work with it, after transplantation it is too sensitive to contact. In general, the existing manufacturing methods give extremely unpredictable results.

In recent years, with the help of new technologies, scientists have managed to develop much more advanced substrates in which skin and epidermal components dynamically interact with each other both during maturation in the laboratory and after transplantation to the human body. In particular, the protein fibrinogen (and its derivative protein fibrin), a component of blood plasma that is synthesized in the liver, is now actively used for the manufacture of such substrates. This protein turned out to be an excellent material for an artificial skin substrate – it is cheap, available in large quantities and convenient to work with.

About ten years ago, a group of Spanish researchers first manufactured and tested a substrate of artificial human skin from skin plasma: see the article "Clinical Results of an Autologous Engineered Skin", published in March 2006 in the journal Cell Tissue Bank. Clinical trials showed encouraging results, but the transplant process itself remained difficult. Firstly, only qualified personnel were required: the engraftment of such a substrate is a scientific project that is carried out by scientists in the laboratory. It was almost impossible to repeat it in an average hospital. In addition, growing the substrate took a long time: 3-4 weeks to grow one square meter.

Given the high demand for artificial leather, scientists have set a goal to optimize the technical process – to reduce the time and cost of work, as well as to automate the work as much as possible. And they did it.

Printing leather on a 3D printer

As studies in recent years have shown, 3D bioprinting is remarkably effective in printing tissues, liver and other living organs. Engineers have studied a number of new materials suitable for bioprinting human organs on Cartesian coordinate robots (that is, on inexpensive modern 3D printers), including hydrogels, polymers and ceramics (for bones). Significant progress has been made in the development of 3D designs for printing complex fabrics. The general approach is to print a preliminary matrix of hydrogel-based layers in order to form cross-links between them and form a 3D framework that will support living cells and other extracellular components embedded in this framework. After a certain maturation time in the laboratory, this printed tissue or organ can be transplanted into the human body.

According to the review of 3D printing methods of human skin (2016, Trends in Biotechnology magazine), there are two main strategies here: printing at the site of damage or printing in the laboratory. In the second case, different approaches are also used.

A group of Spanish scientists from the Carlos III University of Madrid, the Center for Energy, Environmental and Technological Research, Hospital General Universitario Gregorio Marañón and the commercial company BioDan Group have developed a 3D bioprinting process that seems to them the most optimal, taking into account the experience accumulated by their predecessors. They applied the free-form fabrication (FFF) bioprinting technique to print layers in order to form cross-links between them and form a 3D framework, as described above. Fibroblasts and keratinocytes obtained as a result of skin biopsy are placed in separate layers.

A bioprinter for printing human skin. Four cartridges contain blood plasma, fibroblasts, calcium chloride and keratinocytes. The printing is controlled by an Arduino controller (ATmega2560) with RAMPS 1.4 and an LCD display. The printer with two stepper motors runs on free Marlin firmware, the calculation of trajectories for applying layers is performed by the Repetier 0.53 program. A script in C++ is written to control the volume of the applied liquid

The implantation of a sample of printed human skin on a mouse with immunodeficiency was successful. The illustrations below show a histological analysis of the sample 8 weeks after transplantation.

The developed method makes it possible to print functional human skin using simple Arduino equipment and cheap materials: blood plasma, fibroblasts and keratinocytes. Tests have shown that the printed skin is very similar to the real one. According to the developers, this method allows you to print the skin in the volumes necessary for clinical and commercial use. Thus, a 100 cm2 skin fragment is made in 35 minutes, including 30 minutes of fibrin solidification.

Researchers believe that due to automation and standardization of printing, we can expect a significant reduction in the cost of leather in the future.

The scientific work (Cubo et al., 3D bioprinting of functional human skin: production and in vivo analysis) is published in the journal Biofabrication.

Portal "Eternal youth" http://vechnayamolodost.ru  25.01.2017