Tiny Robots Deliver Cell Cargoes In Vivo

In a groundbreaking study, a team of scientists from the City Univ. of Hong Kong has designed and fabricated microrobots capable of delivering cells to targeted sites in live animals.

As regenerative medicine garners more attention, scientists have searched for novel delivery vehicles for cell-based therapies. Delivering cells in vivo will require a structured carrier that can encourage cell adhesion, proliferation, and differentiation, and that can release the cells autonomously. The researchers theorized that a microrobot propelled by an external magnetic field could be capable of meeting these requirements.

They first used computer models to compare the movement of different microrobot shapes and sizes within simulated arteries and veins, and tested several designs, including cuboidal and burr-like shapes. The team found that the burr-like spherical shape resembling a buckyball had the best magnetic and cell-carrying properties. Additionally, the porous scaffold structure of the proposed microrobot mimicked natural extracellular matrix.

They used 3D laser lithography (i.e., 3D printing) to fabricate the bot, and coated it with nickel so it would be magnetic and titanium to ensure biocompatibility. They specifically designed the grid length of the microrobot’s scaffold to be similar to the radius of carried cells. Next, they seeded two different types of cells onto the surface of the microrobot — MC3T3-E1 fibroblasts and mesen-chymal stem cells (MSCs) — via a 12-hr cell culture process (at a concentration of 1×10⁶ cells/mL). Using...