The most advanced practitioner of the still-experimental art of growing leather is Modern Meadow, an American firm. This month it moved from Brooklyn, New York, where its 60 staff have been quietly developing the new material, to a laboratory in Nutley, New Jersey, where they will begin production trials. Modern Meadow, which has raised more than $50m from investors and is collaborating with a number of as-yet-unnamed other firms in the clothing, shoe, furniture and automotive industries, hopes to bring the new material to market within two years.
Factory-grown leather promises several advantages over skins taken from animals. One is that it can be made in convenient sheets with straight edges, rather than being constrained by the irregular shapes that animals come in. Another is that it is more consistent than the natural stuff. It is devoid of the scars, marks and other defects to which real skin is inevitably prone. Nor does it vary from animal to animal in the way that natural leather does. All these facts reduce waste and improve quality. They will also, presumably, please those who feel that animals should not have to die in order that people can have nice shoes and plush seat covers.
To produce its leather, Modern Meadow begins with a strain of yeast that has been genetically engineered to make a protein identical to bovine collagen. Collagen is the principal structural protein in animal bodies. In particular, it gives strength and elasticity to skin. It consists of long chains of amino-acids, the building blocks of all proteins, wound together in threesomes to form triple-helices that are then, in turn, wound together to make fibres.
In animal skins both the synthesis of the initial amino-acid chains and their subsequent winding into fibres are done by special cells called fibroblasts. One crucial trick Modern Meadow’s bioengineers have mastered, though they are reluctant to talk about the details, is encouraging the chains spat out by the yeast to assemble themselves into fibres without the intervention of fibroblasts. Once the fibres are there, though, it is not too hard to persuade them to organise themselves into layers that are, to all intents and purposes, sheets of raw leather. These can then go for tanning, dyeing and finishing in the usual way.
