Periodic Reporting for period 2 - 4DPrintedHeart (4D Printing of Human Vascularized Cardiac Patches and Hearts for Regenerative Medicine)
Reporting period: 2023-01-01 to 2024-06-30
Heart diseases are a major cause of death in the Western world. No sustainable regenerative therapy is currently available, and cardiac transplantation is the only treatment. However, the scarcity of matching heart donors raises the need to develop new regenerative medicine approaches. Recently, our group has shown the use of patient-specific cells and personalized hydrogels to 3D print vascularized cardiac patches. Moreover, we have developed printing technologies that allow the printing of small-scale, cellularized human hearts with the major blood vessels. Despite these and other advances in the field, premature hearts are very basic, and their ability to pump blood and function in vivo is still considered futuristic, requiring several major breakthroughs. In this project, we plan to go far beyond the current state-of-the-art and overcome some of the remaining challenges in the field. We will develop novel 4D printing approaches, allowing the printing of human cardiac patches and whole functional hearts, including ventricles, atria, pacemakers, conduction system, and extensive vasculature, in high resolution. We will decipher the mechanisms underlying the maturation of the printed tissues and hearts, which are essential for synchronous contraction and heart pumping. The functionality of the printed structures will be compared to that of native cardiac tissues and whole natural hearts by examining their reaction to chronotropic and cardiotoxic drugs, proving their additional potential to serve as reliable, predictive drug testing platforms. The printed tissues and hearts will be then heterotopically transplanted (in parallel to the native heart), and their anastomosis (connection) with the host blood vessels, contraction and blood pumping capabilities in vivo will be tested. Finally, we will demonstrate the ability of the printed, vascularized cardiac patches to improve heart function. Successful completion of this ambitious project will provide a sustainable, regenerative therapy for a myriad of devastating maladies.
So far, we accomplished the development of a unique 4D Bioink that changes its physical properties upon exposure to an external stimulus. This physical transition results in a change in the dimensions of the printed elements, enabling high-resolution fabrication of engineered tissues that incorporate small-scale features that cannot be generated by current extrusion-based 3D printing technologies. Using this technique, we managed to print cardiac patches that are populated with multiple types of cells derived from human induced pluripotent stem cells (iPSCs). The printed tissues were then cultured and matured to give fully contracting cardiac patches with perfusable blood vessels. In addition, we developed a 3D bioprinting approach that allows the fabrication of both large blood vessels and small capillaries, each with its own morphology and mechanical properties.
We demonstrated a novel biocompatible, stimulus-responsive hydrogel for use in tissue engineering. The hydrogel is composed of multiple materials that synergistically create a hybrid with both the supportive microenvironment cells needed to develop properly and the augmented, 4D behavior of smart materials. We have demonstrated that this hybrid material can serve as a bio-ink for the 3D bioprinting of functional, vascularized cardiac tissue. As a result of the smart bio-ink’s unique 4D behavior, we have demonstrated the first successful printing of a cell-lined capillary-sized blood vessel. The hybrid hydrogel and the use of one-step coordinated multi-kinetic 4D printing will enable 3D printing techniques to be used on a miniaturized scale, which will serve to usher in a new era of 4D bioprinting in which tissue units can be printed within organs in their native size at high resolution. Future experiments will assess the functionality of these printed, engineered cardiac tissues and heart in the context of a living animal and, importantly- their therapeutic potential in regenerating a failing heart.