Harvard scientists have brought organ engineering a step closer to reality with a breakthrough in 3D bioprinting.
Researchers have developed a new technique that enables the creation of vascular networks within human cardiac tissue that closely mimic the structure and function of natural blood vessels.
The innovative approach, detailed in Advanced Materials, involves using a ‘coaxial SWIFT’ (co-SWIFT) method.
This technique allows for the 3D printing of vessels with a dual-layered architecture, which is crucial for withstanding blood flow pressure and supporting the long-term survival of implanted tissues.
Teams from Harvard’s Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences (SEAS) collaborated to advance the goal of growing functional human organs outside the body.
Paul Stankey, the study’s first author and a graduate student at SEAS, said: ‘Building on our previous SWIFT technique, which patterns hollow channels within living tissues, co-SWIFT replicates the multi-layered structure of native blood vessels. This method significantly enhances the robustness and functionality of bio-printed tissues.’
The core innovation lies in a specialised nozzle that can print two types of bioink simultaneously – a collagen-based shell ink and a gelatin-based core ink.
The nozzle’s design allows it to puncture previously printed vessels, forming interconnected vascular networks that enable effective oxygenation of tissues. This process is pivotal for maintaining the viability of lab-grown organs.
In a series of experiments, the team successfully printed these vascular structures in a granular hydrogel matrix and a new matrix called uPOROS, which mimics the dense, fibrous nature of living muscle tissue.
By infusing the shell ink with smooth muscle cells (SMCs) and perfusing the resulting vessels with endothelial cells (ECs), the researchers created vessels that functioned similarly to natural blood vessels, with significantly reduced permeability.
The most striking results came when the team printed a vascular network into human cardiac tissue composed of tiny spheres of beating heart cells, known as organ building blocks (OBBs). After seeding the vessels with ECs, the cardiac tissue remained viable and began beating synchronously after five days, responding to cardiac drugs like natural heart tissue.
In a demonstration of the method's potential for personalised medicine, the researchers 3D-printed a model of an actual patient’s left coronary artery into the cardiac tissue, showcasing the capability to create patient-specific vascularised organs.
Looking ahead, the team, led by Wyss Core Faculty member Jennifer Lewis, plans to further refine this technology by incorporating self-assembling capillary networks to replicate the full complexity of human vasculature.
Wyss founding director Donald Ingber said: ‘This work represents a significant step toward engineering functional human tissues that could one day be implanted into patients. The determination and innovation shown by this team are truly commendable.’
Grants from the Office of Naval Research and the National Science Foundation supported the research.
