Fake plastic cells

BrownUniversity researchers have made plastic replica cells so realistic they may even fool real cells into growing along them to repair damaged tissue.

Biomedical engineer Diane Hoffman-Kim and her research team made the fakes using a novel two-part moulding process. The copies looked so authentic, Hoffman-Kim couldn’t tell if they were real or rubber at first.

‘When I saw the images from the microscope, I said, OK, I can’t tell the difference,’ Hoffman-Kim said. ‘It was pretty amazing, and just what we wanted.’

The main cells used in the experiments were Schwann cells, which protect peripheral nerves by wrapping around their axons to create insulating myelin sheaths. Schwann cells also direct axon growth during cell development and repair.

Hoffman-Kim, an assistant professor in the Department of Molecular Pharmacology, Physiology and Biotechnology and the Division of Engineering, said the realistic replicas could be used in laboratories to help scientists understand how these critical support cells sustain and direct nerve growth.

The replicas could also, eventually, be used in hospitals to help doctors regenerate nerves. If a patient’s nerves are severed during a vehicle accident or other injury, a device coated with the imitation cells could be implanted into the injured area to help stimulate nerve growth and repair damaged tissue. Tissue engineers are currently testing such nerve guidance channels in animals and, in a few cases, in humans.

‘If the goal is to regenerate nerves, you want to create the right environment for cells to grow,’ Hoffman-Kim said. ‘One way to get the environment right: Make the surface that cells grow on as realistic as possible.’

The cell duplication technique could have many other applications. Hoffman-Kim and her team have also reproduced smooth muscle cells, and they plan to experiment with other cell types.

To make the replicas, cells were grown in the lab then preserved in chemicals to stiffen them. Next, researchers poured liquid silicon over the cells and let the mixture harden. The thin, transparent membrane then had to be carefully peeled off without tearing it. To make a relief, which would show the cell shapes rising up from the surface, this was used as a mould and the pour-and-peel process was repeated.