Human heart muscle cells divide after a heart attack in tissue taken during bypass surgery

Mitosis is a cell caught in the act of dividing. Counting it tells you a division started. It does not tell you that a working muscle cell finished the job. The University of Sydney announcement carries no counts at all: not the number of dividing cells, not the number of patients sampled ^[17]. Those are the figures an amplification strategy needs, because a drug that doubles a rate is only interesting once you know what it is doubling. A heart attack can destroy as many as one third of the cells in the human heart ^[4].

The sampling is what lifts this above an autopsy observation. Diseased and non-diseased tissue came out of the same heart, so each patient supplies their own comparison and differences between donors drop out of it ^[6]. The technique was developed by Paul Bannon and Sean Lal, who hold joint appointments at the University of Sydney, Royal Prince Alfred Hospital and the Baird Institute ^[7]. Bypass patients are a particular population: chronic coronary disease, an elective operating date. The material does not say how long after their heart attacks the tissue was taken ^[17], and that interval decides whether the response is a brief window after injury or something still running in scarred muscle years later.

Robert Hume, the paper's first author and lead of translational research at the Baird Institute ^[10], was direct about the distance between the finding and a treatment. "Although this new discovery of regrowing muscle cells is exciting, it isn't enough to prevent the devastating effects of a heart attack. Therefore, in time, we hope to develop therapies that can amplify the heart's natural ability to produce new cells and regenerate the heart after an attack," he said ^[8].

The alternative explains why a weak repair process is worth chasing at all. Australia has about 144,000 people living with heart failure and performs about 115 heart transplants a year ^[13][14]. Divide one by the other and you get roughly 1,252 people with the condition for every transplant performed ^[15]. Transplant is the only cure the University of Sydney names ^[12], and cardiovascular disease accounts for nearly 24 percent of Australian deaths ^[3].