new, large-scale method developed at Harvard University for turning human embryonic stem cells into fully functioning beta cells capable of producing insulin.
There also is a lot riding on the outcome of the ViaCyte trial—at least symbolically—for the California Institute for Regenerative Medicine (CIRM). The state stem cell agency has allocated $3 billion in funding for stem cell research over the past decade, but there are few, if any, examples of CIRM-funded programs that resulted in stem cell-based “cures” for untreatable diseases or disorders.
ViaCyte is among a relatively small number of privately held companies that has received multiple rounds of CIRM grants, including a $16.6 million award in September to help fund the current clinical trials. The company also has raised venture funding from investors that include Johnson & Johnson (Janssen Healthcare Innovation), Sanderling Ventures, and the Johnson Trust.
Type 1 diabetes is a chronic, life-threatening condition in which the immune system attacks cells in the pancreas called beta cells, whose job it is to produce insulin, a hormone needed for cells to produce energy from glucose. With their natural supply of insulin cut off, people with type 1 diabetes need an outside source of the hormone—usually via an insulin pump or frequent injections—but it’s tricky to maintain proper blood sugar levels using insulin alone.
ViaCyte’s technology provides a way for the implanted islet cells to produce the full repertoire of pancreatic hormones, which would pass into the bloodstream through the packet’s semi-permeable membrane. The implanted cells would be protected from immune attack because the patient’s immune cells can’t get through the packet’s outer membrane.
In their presentation, D’Armour and Henry said ViaCyte has genetically engineered a proprietary line of stem cells to develop as pancreatic progenitor cells, called PEC-01 cells. Once implanted in a packet under the skin, the cells are designed to mature and further differentiate into insulin-producing beta cells and related islet cells, which make other hormones that balance the effects of insulin and control other aspects of digestion and metabolism.
In pre-clinical animal tests, ViaCyte says over a thousand implants have matured into insulin-producing grafts.
The packets come in two sizes—a 20-microliter one about the size of a fingernail and a 250-microliter one about as big as a stick of chewing gum. Doctors at UC San Diego plan to implant two large packets and four small packets in each patient’s lower back. One of the small packets will be removed every four weeks and checked to make sure the PEC-10 cells are normal and healthy.
The 250-microliter packets could remain implanted for as long as two years, Henry said. “We do believe that over time, [dead] cell debris will accumulate, and we plan to replace the device,” he said.
Federal health regulators are expected to review results of the initial cohort. With their approval, Henry said the trial would expand to include about 40 patients at five or six medical centers across the United States.
The chief goal of the trial is to make sure the grafted cells and packet can be safely implanted in humans. But ViaCyte CEO Paul Laikind said the study also was designed to help the company determine the right dosage, that is, how many grafted cells are needed to produce appropriate hormone levels.
Insulin levels fluctuate with meals and other activities, and patients who get the grafted cell implants will also need insulin injections to control spikes in their blood sugar levels. “What we’re trying to replicate is at least basal insulin levels, which would still be a major advance,” Henry said.
