Scientists have printed cartilage without an artificial matrix

Oleg Lischuk, N+1

American scientists have improved the technique of 3D-printing cartilage. They managed to do without an artificial intercellular matrix, using only cellular material, which is closer to the natural development of cartilage tissue. The results of the work are published in the journal Scientific Reports (Yu et al., Three-dimensional bioprinting using self-assembling scalable scaffold-free “tissue strands” as a new bioink).

Most experimental 3D cartilage printing technologies use hydrogels in which chondroblasts (cartilage tissue cells) are immersed. According to the head of the study, Ibrahim Ozbolat, such an approach does not allow cells to exchange signals, as it happens in living cartilage, as a result of which the artificial tissue does not have the necessary mechanical characteristics.

Employees of the Universities of Pennsylvania and Iowa, as well as the Massachusetts General Hospital, introduced chondroblasts into microtubules made of alginate (a biocompatible polysaccharide obtained from algae) with a diameter of 0.75 to 1.25 millimeters. They were placed in a nutrient medium for a week. During this time, the cells proliferated and fused with each other, forming threads about eight centimeters long.

Flow diagram of the technological process (figure from the article in Scientific Reports)

Scientists have developed a special nozzle for a 3D printer that allows the use of elastic cell filaments purified from alginate as "ink". This technology allows you to print cartilage of any shape with any orientation of the fibers composing it, bringing the result as close as possible to the structure of natural cartilage tissue.

Half an hour after printing, the cellular filaments are fused so that the cartilage billet can be moved to the nutrient medium for maturation. The maturation process takes about a week. As the experiment has shown, this technology causes minimal damage to cells that retain the ability to proliferate and synthesize glycosaminoglycans (the main substance of cartilage). Immunochemical analysis revealed sufficient expression of specific RNAs and proteins. Implantation of artificial cartilage into a sample of defective bone and cartilage tissue showed that it can undergo further remodeling by interacting with the recipient's body.

The mechanical properties of printed cartilage are better than those of hydrogel analogues, but they are inferior to natural tissue. Ozbolat expects to improve them by applying pressure during maturation, as it happens with real cartilage growth. In addition to implantation, artificial tissue can be used to simulate diseases and test new drugs.

Portal "Eternal youth" http://vechnayamolodost.ru  30.06.2016