Researchers are working to improve 3D printing by overcoming hurdles that decrease printing efficiency, particularly with larger structures. A joint effort of several universities yielded a technique that improves the vascularization (formation of blood vessels) in printed tissues by utilizing food dye. The technique allows researchers to label and track where the blood vessels and other functional structures would be located in the organs, improving the survival of the printed structures thereby overcoming a major hurdle [survival] of 3D tissue printing. This is particularly important in organs like lungs, where different, overlapping vessels are required for the transport of blood and oxygen, with the dye helping to distinguish between them.
The American Chemical Society (ACS) has published a study that uses 3D printing to create organ frames that can be populated with cells to resemble fully fledged organs. The researchers used a structural sugar called cellulose that plants, archaea and some bacteria use for structural support in their cells. This structural component is also used in making paper, and it is therefore easy to store for prolonged periods of time and inexpensive to produce. Additionally, since cellulose structures are easy to manipulate, the researchers were able to create channels resembling blood vessels, which they then populated with human epithelial cells that typically line blood vessels.
Researchers in Tel Aviv have printed the first vascularized heart made from human stem cells. For the first time, researchers successfully printed heart tissue along with the blood vessels necessary for the heart to be operational. In a miniaturized version, the researchers also incorporated the chambers of the heart. The next step is scaling up the size of the printed heart to the size typically found in humans. Researchers believe a successful scaling up of the process would accelerate parallel efforts to bio-engineer organs in vitro and ameliorate the vast organ shortage, particularly with hearts.
Researchers at North Carolina State University, led by Assoc. Prof. Rohan Shirwaiker, have created a method to “herd” stem cells into desired structures using a biological 3D printer to create specialized structures more easily, overcoming one of the major hurdles in biological 3D printing. While researchers rely on biological scaffolds to help the stem cells differentiate into a particular organ or tissue, this new technique gives the researchers more control in guiding the cells into the desired structure.
12 years ago, Dr. Anthony Atala, a leading stem cell specialist at Boston Children’s Hospital, created a lab-grown bladder from a patient’s own stem cells. The procedure involved obtaining a sample from the patient’s bladder, and culturing the stem cells to grow into a full-sized, functional bladder. 12 years following the procedure, the patient is thriving and has experienced no long-term adverse effects from the regenerated bladder. Since then, the differentiation protocols utilized to grow the bladder have been successfully adapted to grow other functioning tissues like skin, cartilage and urethras, which is indicative of the paradigm shift stem cells represent in treating organ deficiencies.
In a breakthrough study, 3D printed organs have been vascularized to sustain the growing tissue and bring printed organs one step closer to fruition. Currently, hundreds of thousands of Americans are on waiting lists for life-saving organs, and 20 patients die waiting each day. This innovative research by Prellis Biologics is making headway to allow for more effective and efficient printing of organs. 3D printing has had to overcome 2 major obstacles: the development of a biological scaffold to allow for three dimensional growth of cells into the desired organs, and the oxygenation and nutrient delivery to the growing tissue for prolonged periods of printing time using blood vessels. Though a biological medium for 3D tissue growth has already been developed, Prellis has created a more effective an efficient method of vascularizing the growing organ tissue, as well as expediting the printing process as a whole.
Researchers at Newcastle University are 3D printing corneas utilizing stem cells. The process involves mixing stem cells in a bio-gel which is derived from seaweed and collagen that allows these stem cells to be cultured and printed easily and efficiently into fully functioning corneas. The cornea plays an important role in focusing light that enters the eye. Technically, blindness caused by corneal damage is easily reversible with a corneal transplant. However, there is a vast shortage of donor corneas due to general organ and tissue donation shortages. In addition, there is also a significant risk of rejection - as is the case with any donated tissue.