A tiny device could be used to improve the safety and effectiveness of cell therapy treatments for patients suffering from spinal cord injuries.

In cell therapy, clinicians create what are known as induced pluripotent stem cells by reprogramming some skin or blood cells taken from a patient. To treat a spinal cord injury, they would coax these pluripotent stem cells to become progenitor cells, which are destined to differentiate into spinal cord cells. These progenitors are then transplanted back into the patient.

These new cells can regenerate part of the injured spinal cord. However, pluripotent stem cells that don’t fully change into progenitors can form tumors.

The research team developed a microfluidic cell sorter that can remove about half of the undifferentiated cells — those that can potentially become tumors — in a batch, without causing any damage to the fully-formed progenitor cells.

The high-throughput device, which doesn’t require special chemicals, can sort more than 3 million cells per minute. In addition, the researchers have shown that chaining many devices together can sort more than 500 million cells per minute, making this a more viable method to someday improve the safety of cell therapy treatments.

Plus, the plastic chip that contains the microfluidic cell sorter can be mass-produced in a factory at very low cost, so the device would be easier to implement at scale.

The high-throughput microfluidic sorter, which can sort cells based on size, had been previously developed by the CAMP team after more than a decade of work. It has been previously used for sorting immune cells and mesenchymal stromal cells (another type of stem cell), and now the team is expanding its use to other stem cell types, such as induced pluripotent stem cells.

The microfluidic device leverages this size difference to sort the cells. The researchers showed that their device could remove about 50 percent of the larger cells with one pass. They conducted experiments to confirm that the larger cells they removed were, in fact, associated with higher tumor risk.

Importantly, the low-cost microfluidic sorter, which can be produced at scale with standard manufacturing techniques, does not use any type of filtration. Filters can become clogged or break down, so a filter-free device can be used for a much longer time.