Undoubtedly, medical nanotechnology. It is really, really, hard to create something small enough to act as like a cell but progress is being made pretty rapidly.
As we advance in nanotechnology, we’ll be able to feed or kill cells nearly at will. Most disease will be stopped pretty quickly, including cancer. We can rebuild cells and possibly limbs and enhance a lot of physical functions by increasing various types of muscle cells.
While progress is being made on it currently, a more well-known and better understood piece of treatment for cancer is coming: using nanotechnology to target cancer cells by identifying known cancer-indicating molecules. (Research I used: Doctors Excited by New Cancer Treatment)
Curing cancer is a huge goal of the scientific medical community and they’ve made progress with another treatment, this one using genetics to train your cells to attack cancerous cells. If available for widespread use, it could be a huge boost to our health and happiness. Here’s the article if you’d like some more in-depth info: Inside Cancer’s Newest Miracle Cure