3D bioprinting of microfluidic systems for cardiac regenerative medicine: from biofabrication to organ-on-a-chip.

Cardiovascular diseases remain a leading cause of mortality worldwide, highlighting the urgent need for advanced therapeutic strategies in cardiac regenerative medicine. Among emerging technologies, 3D bioprinting has revolutionized the fabrication of biomimetic tissues by enabling precise spatial control over cells and biomaterials. At the same time, microfluidic systems, also referred to as "organ-on-a-chip" platforms, have provided dynamic environments that closely mimic natural cardiac physiology. In this review, we first summarize the structure and function of the human heart to establish the biological context for cardiac tissue modeling. We then discuss the main 3D bioprinting techniques (droplet-based, extrusion-based, and laser-assisted bioprinting) and highlight their advantages, limitations, and suitability for the fabrication of microfluidic architectures. Key properties of ideal biomaterials for both 3D bioprinting and organ-on-a-chip systems are discussed, with an emphasis on materials commonly used in microfluidic systems. Finally, we provide an in-depth overview of microfluidic systems and explore how 3D bioprinting is being used to create integrated heart-on-a-chip platforms for disease modeling and regenerative therapy. The integration of these technologies holds promise for the development of next-generation platforms in personalized cardiovascular therapy.