Can Fat Cells Regenerate?

Once a fat cell is removed from the body, it will not regenerate or return. If, after liposuction, you gain a significant amount of weight, the remaining fat cells may swell. This could negate the good results you worked hard to achieve. In the case of small indentations from fat grafting, even gaining a small amount of weight could cause enlargement of remaining fat cells. Please see a board-certified dermatologist about how liposuction or noninvasive permanent fat-removal systems, such as CoolSculpting, Thermi and Vanquish, can help you.

I have seen long term indentation from overresection of fat. Possibly collagen formation as a response to trauma, or hypertrophy, not hyperplasia (meaning enlarging size not quantity) could be responsible for the filling in of the indentation.
Contrary to what is commonly thought to be the case in the medical community, fat cells can grow in number if the body weight increases above 170% of the ideal body weight. I had come across that fact doing a medical literature search when doing my research in preparation for the book I authored on liposuction published by Penguin Putnam. I doubt this is responsible for your result as you did not mention that you gained significant amount of weight.

However, the remaining fat cells can enlarge with further weight gain. If women are pear shaped and then have liposuction to make them apple shaped, they will be a fat apple if they gain 30 lbs., not a fat pear.

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.