Cardiac bioprinting offers promising alternatives to transplants by engineering functional tissues, addressing the heart’s limited regenerative capacity. However, it is functional maturity, rather than fabrication feasibility, that now limits the translational progress of bioprinted cardiac constructs. To quantify this gap, we hired a systematic review methodology by which a total of 54 eligible cell-laden studies were analyzed using a six-level Functional Readiness Ladder (T0–T5) adapted from Technology Readiness Levels, together with fixed Reporting (8-item) and Rigor (5-item) checklists. Among the analyzed studies, extrusion-based printing predominated (27/54; ~50%), while embedded, hybrid, inkjet, light-based, and scaffold-free modalities each contributed ≤13%. Functional readiness clustered at early tiers (T1 = 20%; T2 = 61%; T3 = 4%; T4 = 15%), with no studies reaching T5. Checklist scores were saturated (median 2/2 for both Reporting and Rigor), confirming that translational limitation stems from incomplete functional maturation rather than poor documentation. Exploratory contingency analyses suggested that higher-tier constructs more often employed fibrininclusive matrices, extrusion-based bioprinting, and mesenchymal stromal cell as a supporting population, although none remained statistically significant after correction for multiple testing. Collectively, these findings indicate that while bioprinted cardiac constructs consistently achieve contractile function, in vivo performance remains limited and inconsistent. Establishing a standardized Tier-3 benchmark (requiring force, electrophysiology, and pharmacologic response measured on the same printed construct) would enable auditable cross-laboratory comparison and guide rational material and cell-design strategies. The readiness framework introduced here provides the first quantitative foundation for tracking translational progress across the rapidly evolving field of cardiac bioprinting.

Keywords