Following a myocardial infarction (heart attack), cardiac muscle cells (cardiomyocytes) die, leading to infarcted tissue that cannot contract. Scientists investigated whether transplanting bone marrow stem cells could help repair infarcted cardiac tissue in mice.
They divided the mice with experimental myocardial infarctions into three groups:
After 10 days, the scientists measured the mean ventricular blood pressure of each group. The results are shown in the table below:
| Group | Mean ventricular blood pressure (kPa\text{kPa}kPa) |
|---|---|
| Control | 0.60.60.6 |
| M−1+M-1^+M−1+ | 3.03.03.0 |
| M−1−M-1^-M−1− | 1.81.81.8 |
Ten days after transplantation, histological analysis showed that in the M−1+M-1^+M−1+ group, 72%72\%72% of the infarcted tissue was made up of newly differentiated cardiomyocytes. The control group had no new cardiomyocytes.
Assuming that the increase in mean ventricular blood pressure above the control baseline is directly proportional to the percentage of infarcted tissue replaced by new cardiomyocytes, calculate the percentage of infarcted tissue made up of new cardiomyocytes in the M−1−M-1^-M−1− group.
