Despite the high hopes surrounding stem cells’ potential to form replacement tissue for medical use, biologists are still struggling in the lab to get these finicky cells to transform into the needed tissues. Now Cartilix, a startup in San Carlos, CA, is offering a technology that might help: polymer materials that direct the growth and development of stem cells.

The startup is working on polymer gels that would be implanted into the joints of arthritic patients and serve as scaffolds upon which the patients’ own bone marrow stem cells would form new cartilage. The stem cells would come from the blood that naturally seeps into the joint area during the implantation procedure; after new tissue forms, the polymer would biodegrade. The hope is that this treatment will help patients “get their own cartilage back” and avoid joint replacement surgery, says Frank Huerta, Cartilix’s CEO.

Stem cells require cues from their environment – including growth factors secreted by other cells and even mechanical pulling forces – in order to transform into more mature and specialized cells and tissue. Scaffolds can provide those cues, says Jennifer Elisseeff, a biomedical-engineering professor at Johns Hopkins University and Cartilix’s scientific cofounder. With these scaffolds, “our goal is to mimic what the cells normally see in the body,” she says. Cartilix’s gels, for example, would be infused with growth factors that encourage the growth of the right kinds of cartilage.

Cartilix isn’t the only group combining polymers with stem cells. MIT researchers are growing human embryonic stem cells on hundreds of polymer materials to test their interactions (see photo). But Cartilix stands out because its treatments wouldn’t involve cell transplants; rather, the polymer would prompt the patient’s own cells to form new tissue. Stem-cell-based treatments remain years away, but Cartilix and its competitors may have provided a scaffold they can grow on.