There is evidence from flat worms that electric fields is how cells naturally move in the right directions with purpose. However they produce the fields chemically via ion gradients.

There's a very cool researcher who used this method to create flatworms with heads (or tails) on both sides. https://www.cell.com/biophysj/fulltext/S0006-3495(17)30427-7

IMO the issue is with unhealthy people, things like poor circulation reduces the body's ability to produce the natural ion gradients and thus why the external electric field helps.