The possibility of using our own cells to perform medical tasks within the body is tantalizing, as it would avoid the immune responses that can occur with synthetic objects. Researchers at Jinan University in China have now developed a method to control and move white blood cells within a living organism. The technology relies on optical tweezers consisting of highly focused laser beams that can grab and hold tiny objects. The researchers showed that they could manipulate neutrophils within the tails of zebrafish using such tweezers, and performed tasks using the “neutro-bots”. These included picking up and transporting nanoparticles, leaving the vasculature and entering nearby tissues, and engulfing cellular debris. The technology could be useful for drug delivery and other medical procedures involving microrobots. Microbots have enormous clinical potential, from delivering drugs to precise locations within the body to performing surgical tasks. However, while microrobots are edging closer to a clinical reality, many such devices consist of synthetic components, putting them at risk of immune attack and potentially limiting their effectiveness. If a large portion of delivered microrobots end up inside a while blood cell or hopelessly covered in antibodies, the robot revolution could grind to a swift halt. To address this, these researchers have turned to our own cells as a potential source of microrobots, and they chose a cell type that might otherwise cause trouble for microrobots – white blood cells. This choice makes a lot of sense, since white blood cells can travel through the vasculature, engulf objects, and leave the vasculature to enter nearby tissues. These highly motile cells are therefore well-suited to act as our agents of change in the body. To manipulate the cells, the Chinese team used optical tweezers, which are a set of focused laser beams. Previous work had shown that it was possible to move neutrophils about in a Petri dish using lasers, but this latest study translated that to a living organism, the zebrafish. The researchers showed that they could move the neutrophils within zebrafish tails at a speed of 1.3 µm/s, which is three times faster than normal speeds for this cell type. They also showed that the manipulated neutrophils could engulf cellular debris and the cells were also able to engulf and transport nanoparticles, and leave the blood vessels to enter nearby tissues. Source
