Tissue Resembling Cartilage Grown from Stem Cells

Researchers have caused stem cells from adult goats to grow into tissue that resembles cartilage, a major step toward creating a minimally invasive procedure that could be used to repair injured knees or other body parts.

In such a procedure, doctors would inject fluid filled with stem cells and nutrients into damaged tissue, then use light to harden the liquid into a stable gel. Stem cells within the gel would multiply and form new cartilage or bone to repair injured tissue. The research team, at Johns Hopkins University (Baltimore, MD, USA), say restoration of cartilage would be especially useful because cartilage does not naturally regenerate. Another advantage of this procedure would be that patients are repaired with living tissue rather than metal or plastic replacement parts.

The team is using adult multipotent stem cells, since these can be stimulated to produce different types of tissue. In theory, patients would donate their own stem cells prior to the procedure, reducing the likelihood of infection and tissue rejection. In the current study, the researchers used a polymer fluid laced with cartilage cells, called chondrocytes, that could be injected under the skin. The liquid is hardened by shining an ultraviolet light through the skin. The solid material, called a hydrogel, forms a scaffold upon which cells can reproduce and form new tissue. The cells thrive because hydrogels contain plenty of water. Lab tests show that the bone precursor cells are producing calcium, a first step toward osteogenesis.

"Other researchers have formed cartilage and bone from stem cells in the laboratory. But by applying this to the injectable hydrogel, we think we've come up with a clinically practical way to deliver the cells to the site of an injury, where they can grow to replace injured bone or cartilage,” said Jennifer Elisseeff, assistant professor in the department of biomedical engineering at Johns Hopkins.




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