Scaffold regenerates rabbit knee cartilage to 91% of natural thickness

A rabbit’s damaged knee now carries a tiny structure built to vanish. Researchers led by Prof. Aleksandra Ovsianikov at TU Wien, with PhD student Oliver Kopinski-Grünwald and Vienna-based trauma and medical centers, filled a cartilage defect with a cell-loaded mesh made from BIO INX’s DEGRAD INX resin. After twelve weeks, regenerated tissue reached approximately 91% of the thickness of natural cartilage.

The scaffold began as spherical printed structures approximately 0.3 mm in diameter, about the size of a grain of sand. Researchers seeded them with cartilage cells grown from stem cells, let the cells mature and assembled the building blocks into a larger implant. The material supported and organized the cells, then was designed to gradually break down as new tissue developed.

The printing method is multiphoton lithography, a laser-based technique capable of resolutions below one micrometer. That precision creates a dense, organized microenvironment for cells. The difficult combination was not just printing: the material also had to be biodegradable and biocompatible. The study marks the first move of this micro-scaffold approach from a laboratory dish into a living organism.

The result is not yet a human therapy. The evidence comes from a specific in vivo experiment in rabbits, and the regenerated tissue was approximately 91% as thick as natural cartilage, not fully equivalent to it. Histological analysis called the tissue “nearly normal cartilage,” while the untreated group showed a clearly weaker result.

In practical terms, the approach could potentially allow cell-loaded building blocks to be injected into irregular cartilage defects without opening the joint. The blocks could adapt to the damaged area while the temporary scaffold disappears. That possibility follows 10 years of work on the micro-scaffold strategy by Ovsianikov’s group, with certification and validation still measured in years.