Christian Stemberger
2015, Germany
Fishing for cells

Christian Stemberger fishes specialized immune cells out of donor blood. He wants to use them to treat infections, autoimmune conditions, and even cancer.

Christian Stemberger loves to go fishing, preferably in the Isar river. And the Bavarian knows that in order to attract certain kinds of fish, you have to choose the right hook. This is the challenge the molecular biologist faces, not only in his spare time, but also in his research – which has recently stunned experts in the field and is raising high hopes in the battle against disease.

And though Stemberger isn’t catching fish at the biotech hub Stage Cell Therapeutics in Göttingen, a spin-off of the Technical University in Munich, he doesn’t proceed much differently in the lab than he would at the riverside. What Stemberger is trying to catch are so-called T-cells, an important component of the immune system. He wants to administer them to patients who are immunocompromised, for example after cancer treatment. It can take up to a year before the body’s defences are fully re-established. During this time, even simple viruses can be life-threatening, such as the herpes virus cytomegalovirus (CMV), it can cause severe damage to the liver and lungs. “With a rapid reaction force, we can prevent these kinds of diseases,” says Stemberger. “This could revolutionize treatment, after chemotherapy for instance.”

The main difficulty: in order to avoid rejection reactions, the donor’s T-cells need to match the recipient’s genetically. Furthermore, all the different types of pathogens require different kinds of T-cells. So Stemberger began looking for the right kind of hook, one that would harvest just the right kind of T-cell from the donor blood without damaging the sensitive cells. The search took him five years. Stemberger knew that infected cells “call” for help by presenting certain molecules on the cell surface. “Like a warning flag,” says Stemberger. That gave the researchers an idea: Why not use these warning flags as hooks? But as it soon turned out, one artificial hook alone is not enough to catch a T-cell. On the fly, they synthesized another molecule with several hooks. But again, they were disappointed: This time, the hook would cling to the cell wall so persistently that the T-cells were injured in the process and became unusable.

Stemberger pondered the problem for a long time – until he had a flash of inspiration while fishing. Certain fishing hooks are attached to the bait with a predetermined breaking point, as a protection against very powerful fish. “So I integrated a breaking point into our biotechnological hook,” the 34-year-old says. Now the connection breaks as soon as Stemberger adds the substance D-Biotin (Vitamin H). Meanwhile, the researchers have treated more than 100 patients with donor T-cells that were specifically targeted at the CMV virus. After a couple of weeks, the number of viruses in their blood had already decreased. Presently, Stage Cell Therapeutics is working on introducing the method to the market, and Stemberger wants to make it available for other ailments, too. His goal is a whole portfolio of different hooks that could then help treat various infectious or autoimmune diseases. Besides, his approach might also work against tumour cells directly. So Stemberger’s fishing season has only just begun.