Douglas Melton was studying frog eggs at a laboratory in Harvard University when his 6-month-old son Sam was diagnosed with type 1 diabetes. Later, the Melton’s daughter Emma was diagnosed with the same condition.
Melton dropped what he was doing and launched efforts to create insulin-producing pancreatic cells in the laboratory. In people with type 1 diabetes, the beta cells die and diabetes develops due to lack of insulin. Melton wanted to create new tissue from embryonic stem cells to replace the insulin-producing cells. Insulin is the hormone that regulates blood sugar in the human body.
With a 30-person staff in his lab at Harvard, Melton started Semma Therapeutics in an effort to convert stem cells into functioning tissue. “A large fraction of science is a failure,” he says. The project has seen its fair share of dead ends.
Discarded IVF embryos are an unlimited supply of embryonic stem cells. However, the process is not so simple. It took Melton’s lab 15 years to coax an embryonic stem cell to be converted into a pancreatic cell that could sense the presence of glucose and secrete insulin in response like it does in the body.
The team’s first success was in demonstrating blood glucose control for six months in diabetic mice who had received transplanted beta cells. Semma Therapeutics is designing a pouch to protect the cells. The plan is to implant this pouch in humans. The company has raised almost $50 million to conduct these experiments. Globally, insulin is a $30 billion per year market. Add to this, blood glucose monitors and test strips, and the figures are mind-boggling.
In type 1 diabetics, an autoimmune reaction destroys the insulin-producing pancreatic cells. The lack of natural blood glucose control means these individuals have to constantly monitor their sugar levels and take insulin injections to maintain healthy blood glucose levels. “Cellular therapy provides the missing cell,” says Melton.
Semma Therapeutics is also trying to develop an islet from embryonic stem cells. An islet in the pancreas contains a collection of different cell types – alpha, beta, delta and others. This cluster would closely mimic the islets found in the human body. The company is developing a retrievable pouch the size of an iPhone. This pouch will protect the implanted cells from the recipient’s immune system.
Professor David Cooper of the Department of Surgery at the University of Pittsburgh, who is himself working on developing human islets in pigs, is not optimistic about an encapsulating device being able to protect the cells from an immune response.
The device would also require a surgery annually, a daunting prospect for young diabetics. Surgical site scarring is an additional concern. However, Melton says this must be weighed against the inconvenience of thousands of test pricks and insulin injections that diabetics endure every year.
Semma is also working on manufacturing islets from the patient’s own skin cells which have been reprogrammed into pluripotent stem cells. This backup plan is supported by a $5 million grant from a California based stem cell agency.