Can Fat Cells Regenerate?

There is no such thing as regenerating fat cells. We are born with a certain amount of fat cells and that is it. The interesting thing about fat cells is that they can enlarge but not replicate. So it can get bigger with weight gain and smaller with weigh loss.
Hope that answers your question.

You are born with all the fat cells you will ever have. These cells get larger as you store more fat and get smaller as you lose weight. When fat cells are removed with liposuction as with removal for fat grafting, those cells are gone for good. It is probably that the dents you had immediately after the procedure were from post operative irritation. The fat cells left behind may also have been injured and not storing fat properly. I am guessing that the fat harvest did not remove a large volume of fat, so there are no permanent contour defects left behind.
When liposuction is done for shaping and contour reduction, more fat is removed and the number of fat cells in the area are significantly reduced. That treated area will never hold fat to the same degree.