Sunflower pollen may allow the development of stronger 3D printing ink material used for tissue engineering, according to researchers from at Singapore’s Nanyang Technological University (NTU). The pollen-derived “bio-ink” is a viable alternative to current inks used for 3D printing in the biomedical field (bioprinting) as it can retain its shape when deposited on a surface, without the need for additional support structures.

The functionality of the new ink was apparent in the 3D printing of a five-layer implantable bioscaffold – a three-dimensional structure used to regrow tissue within the body; it provides anchor points for human tissue cells to be seeded onto the structure. The bio-ink ensured 96% to 97% efficiency of the bioscaffold at retaining the cells, which could go on to reproduce and form replacement biological tissue.

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This efficiency is claimed to be similar to that of 3D cell culture platforms made of inverted colloidal crystal hydrogels, which take more time and effort to build.

The adaptive properties of the pollen microgel particles used in the bio-ink could also conceivably be used to transport medication within the body or enable toxicity testing.

“Through tuning the mechanical properties of sunflower pollen, we developed a pollen-based hybrid ink that can be used to print structures with good structural integrity,” said Professor Cho Nam-Joon, of the School of Material Sciences and Engineering, NTU.

“Utilising pollen for 3D printing is a significant achievement as the process of making the pollen-based ink is sustainable and affordable. Given that there are numerous types of pollen species with distinct sizes, shapes, and surface properties, pollen microgel suspensions could potentially be used to create a new class of eco-friendly 3D printing materials.” The use of pollen, a natural renewable resource, in the biomedical field builds on the NTU researchers’ body of work on repurposing pollen grains as building blocks for various eco-friendly alternative materials that enhance quality of life.

A multidisciplinary research team at Harvard’s Wyss Institute for Biologically Inspired Engineering have fashioned a novel 3D-printed, biocompatible graft that could be used to repair a damaged eardrum. The Phonograft device, as it is called, is also intended to mitigate the pain, drainage, and hearing loss associated with a damaged eardrum.

The eardrum – or tympanic membrane – is a thin but intricate membrane that conducts sound in the ear. The eardrum is however easily perforated by blasts, traumatic injuries, and chronic ear infections, that require reconstructive surgical interventions; surgical failures are common with this type of delicate surgery, making revision surgeries necessary.

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Additionally, patient-derived tissue grafts used as repair very often have imperfect sound-conducting abilities because their structure does not match that of the native eardrum.

After extensive research, the PhonoGraft device was made to mimic the domed shape of the natural eardrum, replete with patterned “wheels and spokes” like a bike wheel. This pattern enables it to vibrate in response to auditory stimulation, and to transmit the sound for further processing by the brain. The Phonograft is composed of a specially developed synthetic polymer-based ink, for 3D printing.

Not only does the implant itself work to restore hearing, but it provides a scaffold for the recipient’s own cells to regenerate. Tests in chinchillas, which have similar ear anatomy and hearing ranges to humans, proved promising.

The researchers believe the novel technology used in the Phonograft could eventually enable permanent repair by first mimicking and then restoring the eardrum’s sound-conducting mechanical properties and barrier functions.

As a bonus, the PhonoGraft can be inserted through the ear canal, thus doing away with invasive surgical repair.

“Three months after implanting our optimised graft into the chinchilla’s ear, we had a genuine eureka moment,” said Dr. Aaron Remenschneider, from the Massachusetts Eye and Ear teaching hospital. “The hearing tests indicated full restoration of sound conduction, which has been a big hurdle. Then we took our first peek down the ear canal with the endoscope. What we were seeing was merely the ghost of our graft that was being replaced with new tissue – a beautifully reconstructed eardrum with its radial-circular pattern.”

According to the researchers, the technology is now entering commercial development as part of high-priority institute project.

A new computer-based technique developed by scientists at Johns Hopkins University School of Medicine has revealed that human cancer cells grown in culture dishes are the least genetically similar to their human sources. The new technique – a tool called CancerCellNet – uses computer models to compare the RNA sequences of a research model with data from a cancer genome atlas to compare how closely the two sets match up.

Cellular RNA is a molecular string of chemicals similar to DNA. It is an intermediate set of instructions cells use to translate DNA into the manufacture of proteins. “RNA is a pretty good surrogate for cell type and cell identity, which are key to determining whether lab-developed cells resemble their human counterparts,” said Dr. Patrick Cahan, associate professor of biomedical engineering at the prestigious university.

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Scientists worldwide rely on a range of research models to improve their understanding of cancer and other disease biology and develop treatments. Among the most widely-used cancer research models are cell lines created by extracting cells from human tumours and growing them with various nutrients in laboratory flasks. Researchers also use genetically engineered mice that develop cancer or implant human tumours into mice, a process called xenografting, or use 3D balls of human tissue known as tumouroids.

Scientists may also transplant lab-cultured cells or cells from tumouroids or xenografts into mice and see if the cells behave as they should—that is, grow and spread and retain the genetic hallmarks of cancer. However, the Johns Hopkins scientists say the process is expensive, time-consuming and scientifically challenging.

The scientists instead found that genetically engineered mice and tumouroids have RNA sequences most closely aligned with a set of genetic baseline data in 4 out of every 5 tumour types tested in their study, including breast, lung and ovarian cancers; and using a 0-1 scoring method, cell lines had, on average, lower scoring alignment to the baseline data compared to tumouroids and xenografts.

In one example from the study, prostate cancer cells from a line called PC3 started to look genetically more like bladder cancer, but ultimately was not a representative surrogate for what happens in a typical human with prostate cancer, Dr. Cahan said.

The goal of the new work was to develop a computational approach to evaluating research models in an accurate and a less cumbersome way. Dr. Cahan and his team will still be adding additional RNA sequencing data to improve the reliability of CancerCellNet.