Whose stem cells?

Removing restrictions on federal funding of embryonic stem cell research was a priority for the Obama administration. This was a major policy shift, hailed as evidence of the President’s commitment to science and progress. Why the fuss about these tiny human cells? Because stem cells are said to be the ‘holy grail’ of regenerative medicine. Ordinary cells are of specific types, such as nerves, skin, heart muscle or other kinds, and can make only more of the same (‘unipotency’). Stem cells, by contrast, are relatively undifferentiated, having the prolonged capacity to multiply and, depending upon circumstances, to differentiate into various cell-types as needed (‘pluripotency’). Thus stem cells can regenerate damaged tissues: their therapeutic potential is enormous.

There are six potential sources for these stem cells currently ‘on the table’: human tissues where stem cells naturally occur; the placenta; other cells which can be reprogrammed to behave as stem cells; pseudo-human organisms; animal–human hybrids; and, finally, human embryos. I consider each in turn. The first is the natural source, used by the body itself since time began and by medicine for the past few decades. These are called somatic or adult stem cells, though they can in fact be taken from people of all ages, not merely adults. Stem cells have been found in almost every body tissue, such as skin, muscle, fat, bone marrow, blood, major organs, brain, nerves, ear, nose and mouth. Sometimes these cells can be derived from the intended recipient, avoiding any immune-rejection difficulties. At other times they are taken from donors. In each case these stem cells are derived without harming anyone and are, in the view of the Catholic Church and many others, far preferable ethically to other routes proposed for deriving stem cells.