If only we could regrow our broken bones like Harry Potter, Skele-gro style. Or, at the very least, heal up like a limb-regenerating newt. Alas, we humans possess no such abilities. Though our bodies cannot break bones, the older we get, the shoddier that patch job gets.

As for cartilage, the crucial cushioning that keeps our bones from rubbing together – once that's gone, it's gone for good. The study was published in Cell.

But a discovery by researchers could change that outlook. A team from Stanford University has finally discovered skeletal stem cells – the cells that give rise to bone, cartilage and the supportive, spongy inside of a bone called humans for the first time.

And the hope is that someday, doctors could use these stem cells to help people regrow broken bones and missing cartilage.   In general, stem cells dog divide and develop into specialized variations, like blood or muscle cells.

Embryonic stem cells, as you might have guessed, are found in embryos. They develop into any type of cell in the body. Adult stem cells, on the other hand, are not as full of potential.  They still develop into different cells, but usually, those cell types are restricted to the organ from which they originate.

Mesenchymal Cells

For instance, neural stem cells reside in the brain, where they divide and ultimately spawn brain cells like neurons. Before now, experts had only uncovered so-called mesenchymal cells in their hunt for human skeletal stem cells. Mesenchymal cells are adult stem cells that can develop into but still could not read home in skeletal stem cells.

Then, they would track the lineage of those cells to see if they evolved into specialized bone cells. They could not find any human cells with enough surface proteins in common with what they would find in mouse cells.

They looked at bones donated from fetal remains, specifically focusing on the still-growing ends, giving researchers a better chance of finding the stem cells they'd been hunting. Since surface proteins were to no-go, they were on the lookout for cells with gene signatures similar to that of mouse skeletal stem cells.

Cartilage

Once they found that they were close enough, they isolated them and popped them in a petri dish. The cells only grew new bits of bone, cartilage and spongy stroma. Though Longaker and company were pretty confident they would find what they were looking for, they still had to make sure.

So, finally, the group turned to chunks of adult bone they'd acquired from people who'd received procedures like hip replacements. The group spotted cells with that same genetic profile and extracted them. And they, too, developed into bone, cartilage, and stroma in Petri dishes.