[Image from Northwestern University]
The materials, aptly named tissue papers, are made from structural proteins that are excreted by cells and give organs their forms and structures. The tissue papers are thin and flexible enough that they can be formed into origami birds.`
Researchers used ovarian, uterine, kidney, liver, muscle and heart proteins to create different types of tissue papers. The tissues were collected from processing pig and cow organs and each paper had different cellular properties of the organ it was made from.
“This new class of biomaterials has the potential for tissue engineering and regenerative medicine, as well as drug discovery and therapeutics,” corresponding author Ramille Shah said in a press release. “It’s versatile and surgically friendly.”
Cells are removed from natural organs, leaving behind natural structural proteins, also called extracellular matrix, to create the tissue papers. The extracellular matrix is dried into a powder and gets processed into the tissue papers. Each paper has biochemicals and protein architecture from the organs it originated from that can help cells act a specific way.
Researchers used bovine ovary tissue paper to grow ovarian follicles when they were cultured in vitro. The follicles produced hormones that are needed for functioning and maturation.
“This could provide another option to restore normal hormone function to young cancer patients who often lose their hormone function as a result of chemotherapy and radiation,” said Teresa Woodruff, the study’s co-author.
One strip of the ovarian paper with follicles could be implanted under the arm to help restore hormone production in cancer patients and women in menopause, according to the researchers.
In other tests, tissue paper made from other organs were able to support the growth of adult human stem cells. Human bone marrow stem cells were placed on the tissue paper and the stem cells were attached to the paper, multiplying over a 4-week period.
“That’s a good sign that the paper supports human stem cell growth,” Adam Jakus, who developed the tissue papers, said. “It’s an indicator that once we start using tissue paper in animal models it will be biocompatible.”
The researchers also say that the organ tissue paper behaves like regular office paper when it is dry and can be stacked in a refrigerator or freezer.
“Even when wet, the tissue papers maintain their mechanical properties and can be rolled, folded, cut and sutured to tissue,” Jakus said.
The researchers suggest that the tissue paper could be beneficial in wound healing because it can provide support and the cell signaling that is needed to help regenerate tissues and prevent scarring while promoting healing.
Jakus accidentally invented the tissue paper when he spilled 3D printing ink while trying to make a 3D printable ovary ink. The ovary ink formed a dry sheet by the time we tried to wipe it up.
“It is really amazing that meat and animal by-products like a kidney, liver, heart and uterus can be transformed into paper-like biomaterials that can potentially regenerate and restore function to tissues and organs,” Jakus said. “I’ll never look at a steak or pork tenderloin the same way again.”
The research was funded by a grant from the Center for Reproductive Health After Disease of the National Centers for Translational Research in Reproduction and Infertility, Google and the Hartwell Foundation. It was published in the journal Advanced Functional Materials.
