If scientists want to look at specific part of the body, they may soon be able to just hit the “print” key.
A research team led by University of California, San Francisco (UCSF), scientists, has developed a technique to print human tissue inside a lab.
The process will allow researchers and medical professionals to study diseases and, potentially, supplement living tissue.
In a study published in Nature Methods, researchers detail the new technique called DNA Programmed Assembly of Cells (DPAC).
Researchers use single-stranded DNA as a type of cell-seeking glue. The DNA is slipped into cells’ outer membranes, covering cells in a DNA-like Velcro.
The cells are incubated and if the DNA strands are complementary, the cells stick, and linked cells eventually lead to tissue.
The key to personalized tissue is linking together the right kinds of cells.
Testing The Technique
To test the technique, researchers printed branching vasculature and mammary glands.
Mammary cells were used in one experiment along with a specific cancer gene.
Researchers were surprised that DPAC worked at all, said senior author Zev Gartner, Ph.D., an associate professor of pharmaceutical chemistry at UCSF.
“Additionally, we were surprised at the self-organizing capacity of many of the cell types we put into the tissues.” Gartner told Healthline. “In many cases, primary human cells have a remarkable ability to self-organize — position themselves correctly — when built into a tissue having a generally correct size, shape, and composition.”
Gartner and his group intend to use DPAC to investigate the cellular or structural changes in mammary glands that can lead to tissue breakdowns like those seen with metastasizing tumors.
Cancer is just one disease researchers could study using DPAC-printed tissue.
In addition, with DPAC-produced cells, the research can be done with tissue in a way that doesn’t affect patients.
"This technique lets us produce simple components of tissue in a dish that we can easily study and manipulate," study co-leader Michael Todhunter, Ph.D., who was a graduate student in the Gartner research group, told PhysOrg. "It lets us ask questions about complex human tissues without needing to do experiments on humans."
A Difficult Process
Copying tissue sounds difficult — and it is.
It turns out that when research tries to replicate science fiction, reality presents more than a few obstacles.
First, to copy tissue, researchers need all the different cell types. In the human body, there are many different specific types of cells and building blocks that need to be assembled correctly.
“To truly copy a tissue you need to get a hold of all the correct cell types,” Gartner said. “Finding the materials to use as scaffolds that appropriately mimic the extracellular matrix found around all tissues in the body remains a challenge."
After assembling the scaffolding, researchers need to install the human equivalent of wiring — blood vessels.
“Vascularizing tissues, i.e., adding blood vessels through which you can perfuse nutrients and reagents, remains a major challenge,” Gartner said. “We’re working on all of these or trying approaches developed by other researchers.”
A Potential Tissue Gold Mine
Regardless of the obstacles, printed tissue is a potential treasure trove.
Functioning printed tissue could be used to test how a person would react to a certain type of treatment. It could even be used in human bodies as functional human tissues of lung, kidneys and neural circuits.
In the short term, researchers are using DPAC to build models of human disease to learn more about ailments in a lab setting.
“These can be used as preclinical models that could significantly reduce the cost of drug development, “ Gartner said. “They might also be used in personalized medicine, i.e. a personalized model of your disease. We are also using DPAC to model what goes wrong in human tissues during key steps in disease progression. For example, during the transition from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma of the breast.”
Long-term applications could be endless.
“We plan to use DPAC to test and evaluate new strategies for building functional tissues and organs for transplantation,” Gartner said. “To pull that off, we need to understand how cells build themselves into tissues and how those tissues are maintained and repaired during normal tissue function and homeostasis.”
The difference between the short-term and long-term usage of technology like DPAC is an understanding of tissues’ complexities. The human body is made up of more than 10 trillion cells of different kinds. Each has a specific role in human function.
“If we can figure that out, we should be able to rationally design approaches towards building replacement tissues and organs,” Gartner said. “It’s a lofty goal, but one which we are better positioned to realize using techniques like DPAC.”