Caption: From stem cells to bone. Human bone cell progenitors, derived from stem cells, were injected under the skin of mice and formed mineralized structures containing cartilage (1-2) and bone (3). Credit: Loh KM and Chen A et al., 2016
To help people suffering from a wide array of injuries and degenerative diseases, scientists and bioengineers have long dreamed of creating new joints and organs using human stem cells. A major hurdle on the path to achieving this dream has been finding ways to steer stem cells into differentiating into all of the various types of cells needed to build these replacement parts in a fast, efficient manner.
Now, an NIH-funded team of researchers has reported important progress on this front. The researchers have identified for the first time the precise biochemical signals needed to spur human embryonic stem cells to produce 12 key types of cells, and to do so rapidly. With these biochemical “recipes” in hand, researchers say they should be able to generate pure populations of replacement cells in a matter of days, rather than the weeks or even months it currently takes. In fact, they have already demonstrated that their high-efficiency approach can be used to produce potentially therapeutic amounts of human bone, cartilage, and heart tissue within a very short time frame.
Caption: Osteoclast cells (red) carve a path through a knee joint (purple and white), enabling a blood vessel to supply the cells (yellow) needed to build new bone. Credit: Paul R. Odgren, University of Massachusetts Medical School
Bones are one of our body’s never-ending remodeling projects. Specialized cells, called osteoclasts, are constantly attaching to old bone and breaking it down, using acids to dissolve the calcium. In the wake of this demolition, bone-building cells, called osteoblasts, move in and deposit new minerals to patch and remodel the bone, maintaining its strength and durability.
Normally, these two types of cells strike a delicate balance between bone destruction and formation. But if this balance goes awry, it can lead to trouble. With osteoporosis, for example, bone removal exceeds formation, yielding progressively weaker bones that are prone to fracture.
Caption: Here we see the host bone (red and blue) growing in a cavity of the implant (brown and sliver). A new coating on the implant encourages this stable bond. Credit: The Hammond Research Group, David H. Koch Institute of Integrative Cancer Research at MIT
Hip, knee, and shoulder joints get worn over time, or damaged by disease or injury. They often require replacement because they cause pain and inhibit movement. Orthopedic surgeons perform more than 1 million joint replacements each year. The worn bone is replaced with plastic or metal implants and cemented in place. The surgery can provide immense relief and restore mobility. But sometimes these implants don’t integrate well with the bone, and ultimately they break free. Replacement surgeries are costly, increase the risk of infection, and are a major challenge for the patient to endure. But recently an NIH-funded team of chemical engineers at MIT developed a special coating for implants that promotes a stronger connection to new bone. Continue reading →