Tiny 'backpacks' for cells created to ferry drugs and assist in cancer diagnosis

Washington, Nov 7 : For the first time ever, MIT engineers have attached tiny "backpacks" in cells, allowing them to deliver chemotherapy agents, diagnose tumours or become building blocks for tissue engineering.

According to Michael Rubner, director of MIT's Center for Materials Science and Engineering and senior author of a paper on the work, this is the first time anyone has attached such a synthetic patch to a cell.

The polymer patch system consists of three layers, each with a different function, stacked onto a surface. The bottom layer tethers the polymer to the surface, the middle layer contains the payload, and the top layer serves as a "hook" that catches and binds cells.

Once the layers are set up, cells enter the system and flow across the surface, getting stuck on the polymer hooks. The patch is then detached from the surface by simply lowering the temperature, and the cells float away, with backpacks attached.

"The rest of the cell is untouched and able to interact with the environment," said Albert Swiston, lead author of the paper and a graduate student in materials science and engineering.

With the help of the polymer backpacks, researchers can use cells to transfer tiny cargoes and manipulate their movements using magnetic fields.

As each patch covers only a small portion of the cell surface, it doesn't hamper with the cell's normal functions or prevent it from interacting with the external environment.

"The goal is to perturb the cell as little as possible," said Robert Cohen, the St. Laurent Professor of Chemical Engineering at MIT and an author of the paper.

The scientists focussed mainly on B and T cells, two types of immune cells that can home to various tissues in the body, including tumours, infection sites, and lymphoid tissues - a trait that could be exploited to achieve targeted drug or vaccine delivery.

"The idea is that we use cells as vectors to carry materials to tumours, infection sites or other tissue sites," said Darrell Irvine, an author of the paper.

Cellular backpacks carrying chemotherapy agents could target tumour cells, while cells equipped with patches carrying imaging agents could help identify tumours by binding to protein markers expressed by cancer cells.

The method also finds uses in tissue engineering-patches could be designed that allow researchers to align cells in a certain pattern, eliminating the need for a tissue scaffold.

It was found that T cells with backpacks could perform their normal functions, including migrating across a surface, just as they would without anything attached.

The researchers can control the cells' movement with a magnetic field by loading the backpacks with magnetic nanoparticles.

They claimed that as the polymer synthesis and assembly takes place before the patches are attached to cells, there's a lot of scope to tweak the process to improve the polymers' effectiveness and ensure they won't be toxic to cells.

The study has appeared online in Nano Letters.

ANI