The principle use of stem cells in the near future is actually research, not therapy - generating diseased cells to order will lower the cost of better understanding the mechanisms of disease and age-related conditions. For example: "scientists have, for the first time, created stem cell-derived, in vitro models of sporadic and hereditary Alzheimer's disease (AD), using induced pluripotent stem cells from patients with the much-dreaded neurodegenerative disorder. ... It's a first step. These aren't perfect models. They're proof of concept. But now we know how to make them. It requires extraordinary care and diligence, really rigorous quality controls to induce consistent behavior, but we can do it. ... We're dealing with the human brain. You can't just do a biopsy on living patients. Instead, researchers have had to work around, mimicking some aspects of the disease in non-neuronal human cells or using limited animal models. Neither approach is really satisfactory. ... With the in vitro Alzheimer's neurons, scientists can more deeply investigate how AD begins and chart the biochemical processes that eventually destroy brain cells associated with elemental cognitive functions like memory. Currently, AD research depends heavily upon studies of post-mortem tissues, long after the damage has been done. ... The differences between a healthy neuron and an Alzheimer's neuron are subtle. It basically comes down to low-level mischief accumulating over a very long time, with catastrophic results. ... The researchers have already produced some surprising findings. ... In this work, we show that one of the early changes in Alzheimer's neurons thought to be an initiating event in the course of the disease turns out not to be that significant."