In early 2010 a Japanese research team grew retina-like structures from a culture of mouse embryonic stem cells. Now, only a year later, the same team at the RIKEN Center for Developmental Biology announced their success in growing a much more complex structure following a similar process — a mouse pituitary gland. This is seen as another major step towards bioengineering replacement organs for human transplantation.

[div class=attrib]From Technology Review:[end-div]

The pituitary gland is a small organ at the base of the brain that produces many important hormones and is a key part of the body’s endocrine system. It’s especially crucial during early development, so the ability to simulate its formation in the lab could help researchers better understand how these developmental processes work. Disruptions in the pituitary have also been associated with growth disorders, such as gigantism, and vision problems, including blindness.

The study, published in this week’s Nature, moves the medical field even closer to being able to bioengineer complex organs for transplant in humans.

The experiment wouldn’t have been possible without a three-dimensional cell culture. The pituitary gland is an independent organ, but it can’t develop without chemical signals from the hypothalamus, the brain region that sits just above it. With a three-dimensional culture, the researchers could grow both types of tissue together, allowing the stem cells to self-assemble into a mouse pituitary. “Using this method, we could mimic the early mouse development more smoothly, since the embryo develops in 3-D in vivo,” says Yoshiki Sasai, the lead author of the study.

The researchers had a vague sense of the signaling factors needed to form a pituitary gland, but they had to figure out the exact components and sequence through trial and error. The winning combination consisted of two main steps, which required the addition of two growth factors and a drug to stimulate a developmental protein called sonic hedgehog (named after the video game). After about two weeks, the researchers had a structure that resembled a pituitary gland.

[div class=attrib]Read the entire article here.[end-div]

[div class=attrib]New gland: After 13 days in culture, mouse embryonic stem cells had self-assembled the precursor pouch, shown here, that gives rise to the pituitary gland. Image courtesy of Technlogy Review / Nature.[end-div]