Fully functional human cartilage grown in lab

In a breakthrough, scientists have successfully grown fully functional human cartilage for the first time in vitro from stem cells derived from human fat tissue.

The study by Columbia University researchers demonstrates new ways to better mimic the enormous complexity of tissue development, regeneration, and disease.

"We've been able - for the first time - to generate fully functional human cartilage from mesenchymal stem cells by mimicking in vitro the developmental process of mesenchymal condensation," said Gordana Vunjak-Novakovic from Columbia Engineering, who led the study.

"This could have clinical impact, as this cartilage can be used to repair a cartilage defect, or in combination with bone in a composite graft grown in lab for more complex tissue reconstruction," said Vunjak-Novakovic.

Vunjak-Novakovic's team succeeded in growing cartilage with physiologic architecture and strength by radically changing the tissue-engineering approach.

The general approach to cartilage tissue engineering has been to place cells into a hydrogel and culture them in the presence of nutrients and growth factors and sometimes also mechanical loading.

But using this technique with adult human stem cells has invariably produced mechanically weak cartilage.

So researchers wondered if a method resembling the normal development of the skeleton could lead to a higher quality of cartilage.

Sarindr Bhumiratana, postdoctoral fellow in Vunjak-Novakovic's Laboratory for Stem Cells and Tissue Engineering, came up with a new approach: inducing the mesenchymal stem cells to undergo a condensation stage as they do in the body before starting to make cartilage.

He discovered that this simple but major departure from how things were usually being done resulted in a quality of human cartilage not seen before.

The team performed measurements showing that the lubricative property and compressive strength - the two important functional properties - of the tissue-engineered cartilage approached those of native cartilage.

The researchers then used their method to regenerate large pieces of anatomically shaped and mechanically strong cartilage over the bone, and to repair defects in cartilage.

"Our whole approach to tissue engineering is bio-mimetic in nature, which means that our engineering designs are defined by biological principles," Vunjak-Novakovic noted.
The study was published in the journal PNAS.