Exocrine Cells Mimic Insulin-Producing Beta Cells

In a new breakthrough in the world of “regenerative medicine”, which attempts to create replacement tissues and body parts as per requirements of patients, scientists have transformed one type of adult cell directly into another inside a living being.

Biologists at Harvard have converted cells from a mouse’s pancreas into insulin-producing cells, bringing in hope for patients of diabetes. If this development can be carried forward into a cure, many diseases might be wiped away, as cells can be tailored to work as replacement for other defective functions within the body.

The study, which follows upon similar ones in the recent months, promises to do away with the cumbersome, time-consuming field of embryonic stem cell research, which is also clouded in controversy.

Through a series of experiments involving mice, the Harvard biologists pinpointed three crucial molecular strains which can completely convert a common cell in the pancreas into the rare insulin-producing ones which are inadequate in diabetes patients.

The new field depends on manipulating master proteins called transcription factors that regulate which sets of genes are active in a cell and thus determine what properties and functions the cell will possess.

The present study conducted by a team led by Qiao Zhou and Douglas A. Melton at Harvard has pinpointed three transcription factors active in the insulin-producing beta cells of the pancreas.

They added the genes for these three factors on to a virus that infects another type of pancreatic cell, known as an exocrine cell. The transformed exocrine cells were seen to produce insulin in mice made diabetic by a drug that kills beta cells.

The mice also showed “a significant and long-lasting improvement” in their diabetic state, the researchers reported Thursday in the journal Nature.

The transformed exocrine cells not only resembled beta cells in function, but in appearance too; and stopped their erstwhile functions altogether. However they did not form the pancreatic islets where beta cells usually group together, making the morphed entities only ‘cells that closely resemble beta cells.’

“It’s kind of an extreme makeover of a cell,” said Douglas Melton, co-director of the Harvard Stem Cell Institute, who led the research. “The goal is to create cells that are missing or defective in people. It’s very exciting.”

The new study has drawn the admiration of researchers worldwide. Robert Lanza, chief scientific officer of Advanced Cell Technology in Worcester, Mass., a developer of stem cell therapies said the new study presents “a whole new paradigm for treating disease.”

Critics of embryonic stem cell research also welcomed the findings of the new study. “I see no moral problem in this basic technique. This is a win-win situation for medicine and ethics,” said Richard Doerflinger of the U.S. Conference of Catholic Bishops, a leading opponent of embryonic stems cells.

Studies in this field got a fillip last year when a Japanese biologist, Shinya Yamanaka, demonstrated how an adult cell can be transformed in to its embryonic state by introduction of four transcription factors.

Last month Patrick Seale and Bruce Spiegelman of the Dana-Farber Cancer Institute in Boston showed how white fat cells can generate brown fat cells, with a single transcription factor. However, many years of research still lie ahead to translate the new findings into viable cures, the researchers said.