Chemists have produced living multicellular structures that could show how organisms evolved in nature and be used in tissue engineering.   

The structures, termed cellosomes, were made by Vesselin Paunov from the University of Hull, UK, and Rawil Fakhrullin from Kazan State University, Tatarstan, Russia. The pair built up the structures by layering yeast cells on to aragonite (rod-shaped) and calcium carbonate (rhombohedral) templates. They coated the yeast cells with a negatively charged polyelectrolyte layer and the templates with a positively charged polyelectrolyte to encourage attraction between them. They then dissolved the templates with ethylene diamine tetra acetic acid to give rod- and rhombohedral-shaped, hollow 3D cellosomes.     

Paunov and Fakhrullin coated the templates with magnetic nanoparticles so they could manipulate them with an external magnetic field. KiBum Lee, an expert in nanotechnology and cell biology from Rutgers, The State University of New Jersey, US, says that 'the magnetic property will be very useful for selective sorting and separation of cells.'   

The team analysed the clusters with fluorescence microscopy and found that the yeast cells were still active in the cellosomes, which remained viable for at least two weeks if stored at 4 ºC. The cellosomes resemble primitive multicellular organisms to a certain degree, so we could speculate that nature has used a similar assembly mechanism in evolution, comments Paunov.   

The technique, Paunov says, 'works not only with yeast cells but also with virtually all kinds of cells. Just imagine the possibilities of combining our technique with stem cells. There are tremendous opportunities for novel ways of engineering tissues - their shape can be directed by the shape of the template.'   

'We are currently working on a simpler technique to produce living cellosomes of various shapes and from different types of cells,' concludes Paunov. 'We are combining several types of bacterial cells to produce symbiotic colonies, which is the next step in the design of an "artificial" living multicellular organism.'   

Alexandra Haywood

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