Scottish scientists have managed to grow an entire organ (a thymus) from a few cells. In mice — this is a long way from human trials.
Starting with a few cells from a mouse embryo, they “reprogrammed” them to turn into thymus cells. They injected them into a mouse, along with some support cells. The cells grew to form a complete thymus. NB: the thymus is a fairly simple organ. The new thymus started producing T-cells.
One problem is that since the thymus grew from foreign cells, there are organ computability problems.