After a severe heart attack, billions of heart-muscle cells die for good, and adult heart muscle barely regenerates. A Nanjing Drum Tower Hospital team, working with a biotech partner, injected 200 million iPSC-derived cardiomyocytes into the infarct region during bypass surgery . The randomized study in Nature Medicine validated a cardiac-regeneration route for the world.
Photo: Science and Technology Daily (respondent-provided photo)
How It Works: Adding Muscle to a Dead Patch of Heart
Heart failure is the common end stage of many heart diseases. Ischemic heart failure after coronary disease is especially common: after a severe heart attack, large areas of muscle die and are replaced by scar tissue that cannot contract, so the heart enlarges and weakens. Medicines, stents and bypass improve blood supply to surviving muscle but cannot bring dead muscle back, and donor hearts are extremely scarce.
Induced pluripotent stem cells (iPSCs) offer a new route. The team takes a small sample of blood cells from a healthy donor, reprograms them back to a pluripotent state, and guides them to become cardiomyocytes—heart-muscle cells that beat on their own rhythm.
During coronary artery bypass grafting (CABG), surgeons use precision injection to place 200 million (2×10⁸) allogeneic cardiomyocytes at multiple points in and around the infarct, like laying fresh bricks into a damaged wall. The goal is both vessel reopening and muscle regeneration. Because the cells come from healthy donors, can be mass-produced and frozen, the product is off-the-shelf—ready when the patient arrives.
The injected cells do more than beat in isolation. In animal work they formed new contractile tissue, released factors that support surviving muscle and vessels, and reduced stress in the border zone around the scar; whether the same mechanisms drive the human gains is still being studied. Delivering the cells during an operation the patient already needs also avoids a separate invasive procedure and shortens the route from trial to clinic.
Healthy donor blood cells are reprogrammed through iPSCs into cardiomyocytes and injected at multiple points during bypass (schematic).
How Treatment Is Given
1 Strict selection
Advanced ischemic heart failure, LVEF ≤45%, NYHA class III–IV, age 35–75, with viable muscle bypass can reach but bypass alone cannot restore function.
2 Off-the-shelf preparation
Healthy donor blood cells are reprogrammed and differentiated into cardiomyocytes, pass standardized quality control and are frozen. Patients do not wait for their own cells.
3 Injection during bypass
During CABG, 2×10⁸ cardiomyocytes are injected at multiple points in the infarct and its ischemic border zone.
4 Post-op monitoring and follow-up
Heart rhythm is watched closely, with planned assessments of function, exercise capacity and perfusion running to 12 months.
Clinical Results: A 20-Patient Randomized Trial
The HEAL-CHF study (NCT03763136), published online August 19, 2026 in Nature Medicine, was the first iPSC randomized controlled study filed with China’s National Health Commission and the largest RCT of iPSC cardiomyocytes for severe heart failure anywhere. Twenty patients were randomized 1:1: the cell group received HiCM-188 during bypass; controls had bypass alone.
At 12 months, 90% of the cell group had recovered to NYHA class II, versus 60% of controls. Six-minute walk distance rose by an average of 168.8 meters, compared with 97.25 meters in controls (P=0.023).
Pumping measures showed the clearest split: stroke volume rose by 9.03 mL in the cell group but fell by 8.41 mL in controls. Resting myocardial perfusion improved significantly (P=0.010), and relative wall thickening in the left anterior descending territory rose by an average of 96.9%. Every patient carried viable but hibernating myocardium—the kind bypass can reach but historically often leaves underperforming.
Safety: No Tumors, No Sustained VT—But Early Rhythm Risk
Tumor formation and dangerous arrhythmias are the two safety questions cardiac regeneration faces most. The prespecified primary safety endpoints were met: neither group had sustained ventricular tachycardia from months 1–6, and no tumors appeared over 12 months.
The study also confirmed that transplanted cells beat in sync with the patient’s own rhythm—a key global validation, the team called it.
Early rhythm risk is real All 10 cell-group patients (100%) developed accelerated idioventricular rhythm (AIVR) 5–7 days after transplantation. Two progressed at 2–3 weeks to clinically meaningful ventricular tachycardia above 140 beats per minute; both resolved fully after electrical cardioversion. This fell outside the prespecified safety endpoints, and future studies must define the risk–benefit balance.
Honest Limits: Local Gains Have Not Yet Lifted Ejection Fraction
At 12 months, the two groups showed no statistically significant difference in left ventricular ejection fraction (LVEF), left ventricular volumes, scar size, NYHA statistical testing or Minnesota quality-of-life scores. Improvements in local perfusion, wall thickening and exercise capacity have not yet been shown to translate into a rise in overall pumping function (EF) or to reverse whole-heart remodeling.
The sample was only 20 patients—10 per group—at a single center and mostly male, so statistical power is limited and the findings need replication, particularly in women and older patients. A nationwide multicenter phase III confirmatory trial has started, and the developer expects the product could reach the market in 2028.
Teams in Japan and Germany are exploring cardiac patches, spheroids and engineered heart tissue; all remain at early stages, with no product approved. The unique value of the Chinese study is its randomized design, giving proof of concept for the injection-based route.
HiCM-188 vs leading cardiac-regeneration programs worldwide
Conditions It Can Treat
• Advanced ischemic heart failure
• Post-MI heart failure with reduced ejection fraction (HFrEF)
• Severe heart failure, NYHA class III–IV
• Heart failure with LVEF ≤45%
• Persistent dysfunction after bypass with viable myocardium
• Non-ischemic dilated cardiomyopathy (explored internationally)
• Mild-to-moderate heart failure (catheter delivery in research)
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