Researchers at Rutgers created a scaffold, or 3D pattern of cells, by assembling Type-1 collagen. collagen is the most abundant tissue in the ECM. Type-1 collagen specifically is the most abundant collagen used to strengthen and support tissues in the body. The researchers chemically modified the collagen such that it can assemble into 3D structures in the presence of ulraviolet light (light with a shorter wavelength than visible light but linger than x-rays and gamma rays). This allowed researchers to control 3D assembly of collagen through light. Similarly, collagen structures can be assembled by controlling pH, temperature and collagen concentration using chemically modified collagen.

Researchers at the Department of Genetics and Pathology in Rudbeck Laboratory studied three vascular endothelial growth-factor receptors (VEGF) responsible for regulating the cardiovascular system. VEGFR1, VEGFR2, and VEGFR3 all function slightly different but together produce cardiovascular development, control endothelial-cell function and the development and survival of blood vessels. They showed the importance of controlling angiogenetic-growth-factors (such as proangiogenic) that are responsible for the formation of blood vessels. Fibronectin is not mentioned by name but other glycoproteins are emphasized for their importance as receptors for VEGF.

Researchers at Harvard were the first to keep a 1cm thick vascularized tissue alive in lab conditions for longer than 6 weeks. They achieved this by co-printing a mixture of bioinks composed of human stem cells, skin cells, cells from umbilical cord vessels, and growth factors. The printed artificial tissue contained a network of embedded blood vessels used for perfusion to keep the tissue alive.

Jordan S. Miller notes that 3D printing facilitated creation of tissue constructs with live cells. However, he argues that in order to engineer functional artificial organs, the construct should contain 1–10 billion functioning cells. Furthermore, these constructs should control the spatial arrangement of cells and contain complex vascular networks and functional nerves.

Jordan S. Miller at Rice University highlighted that more clinical trials, proper tissue fabrication sterilization, sufficient vasculature and quality assurance will lead to good manufacturing practice (GMP) and a standard regulatory process. Miller believes overcoming these obstacles will transition the use of 3D printed tissue from research and development to manufacturing and production.

Michael Potente, Holger Gerhardt, and Peter Carmeliet worked with endothelial cells in order to grow blood vessels in a scaffold smaller than any needle is capable of printing. The cells naturally line the inner surface of the vessel and are responsible for repair and growth of new vasculature. Under predetermined conditions the cell have genes that will be expressed to grow vasculature; a process known as angiogenesis.

Christian Frantz, Kathleen M. Stewart and Valerie M. Weaver compiled information on the extracellular matrix (ECM) and its application in tissue engineering

Dvir and colleagues used a specific type of stem cells called pluripotent stem cells that allowed them to grow and develop vascularization as an embryo would. They are the first to take cells from a patient to print a personalized full size and function heart using bioinks. Bioinks are the printing material that replicates the extracellular matrix and has living cells in it.

HW Kang and others at Wake Forest Institute for Regenerative Medicine used microchannels developed at University of Pennsylvania on an integrated tissue-organ printer (ITOP) so that they can produce human-scale mandible and calvarial bone, cartilage and skeletal muscle.

J.S. Miller and others in the Bioengineering Departmnet of University of Pennsylvenia were able to 3D print living cells together to form a tissue. The current problem is that blood and oxygen was unable to get to the center of the tissue leaving a large dead spot in the center called a necrotic core. They solved this problem by engineering in channels for blood to flow as they do through veins to keep a wide variety of cell types alive.

Researchers at the Department of Genetics and Pathology in Rudbeck Laboratory studied three vascular endothelial growth-factor receptors (VEGF) responsible for regulating the cardiovascular system. They showed the importance of controlling angiogenetic-growth-factors (such as proangiogenic) that are responsible for the formation of blood vessels. Fibronectin is not mentioned by name but other glycoproteins are emphasized for their importance as receptors for VEGF.

Dvir and colleagues used stem cells to print patches of heart tissue and showed that they had functioned properly and contained blood vessels (a sign of healthy tissue). Once they had a process to create the tissue they were able to print a full scale, anatomically correct, functioning heart.

Thomas Hinton and colleagues at Carnegie Melon University developed a hydrogel bath in which a syringe injects another gel that solidifies with a precision up to 100 micro-meters. The gel bath was then removed by raising the system temperature from 22°C (71.6°F) to 37°C (98.6°F) while the deposited material simultaneously remained solidified.

Researchers 3D printed biological material to create different types of cells and repeated the process in a complex way to replicate testable organs such as livers.

Researchers from Center for Nano-scale Systems (CNS) developed a method to 3D print a microchip replicating an organ to test experiments without putting anyone at risk.