A new study of one of our closest invertebrate relatives, the acorn worm, reveals that this feat might one day be possible.
Acorn worms burrow in the sand around coral reefs, but their ancestral relationship to chordates means they have a genetic makeup and body plan surprisingly similar to ours.
A study led by the University of Washington and published in the December issue of the journal Developmental Dynamics has shown that acorn worms can regrow every major body part – including the head, nervous system and internal organs – from nothing after being sliced in half.
“This could have implications for central nervous system regeneration in humans if we can figure out the mechanism the worms use to regenerate.”
The new study finds that when an acorn worm – one of the few living species of hemichordates – is cut in half, it regrows head or tail parts on each opposite end in perfect proportion to the existing half.
Each half of the worm continues to thrive, and subsequent severings also produce vital, healthy worms once all of the body parts regrow.
The researchers also analyzed the gene expression patterns of acorn worms as they regrew body parts, which is an important first step in understanding the mechanisms driving regeneration.
It’s as if the cells are independently reading road signs that tell them how far the mouth should be from the gill slits, and in what proportion to other body parts and the original worm’s size.
Humans can regrow parts of organs and skin cells to some degree, but we have lost the ability to regenerate complete body parts.
Scientists suspect several reasons for this: Our immune systems – in a frenzy to staunch bleeding or prevent infection – might inhibit regeneration by creating impenetrable scar tissue over wounds, or perhaps our relatively large size compared with other animals might make regeneration too energy intensive.
Learn and see more: Our closest worm kin regrow body parts, raising hopes of regeneration in humans
A new technique, developed at EPFL, combines microfluidics and lasers to guide cells in 3D space, overcoming major limitations to tissue engineering.
Future medicine is bound to include extensive tissue-engineering technologies such as organs-on-chips and organoids – miniature organs grown from stem cells. But all this is predicated on a simple yet challenging task: controlling cellular behavior in three dimensions. So far, most cell culture approaches are limited to two-dimensional environments (e.g. a Petri dish or a chip), but that neither matches real biology nor helps us sculpt tissues and organs. Two EPFL scientists have now developed a new method that uses lasers to carve out paths inside biocompatible gels to locally influence cell function and promote tissue formation. The work is published in Advanced Materials.
In the body, cells grow in 3D microspaces that are specific to each type of tissue – liver, kidney, lung, heart, brain etc. These microenvironments are important because they control the behavior of the cells, e.g. how they interact with other parts of the tissue to help it develop, function, and repair. In addition, the microenvironments themselves are very dynamic and adaptable, sending the cells various biochemical signals to adapt their behavior to physiological changes.
This means that any successful merging of biology and engineering must first be able to grow cells in custom-built yet biologically active 3D spaces. Working at EPFL’s Institute of Bioengineering, Matthias Lütolf and his PhD student Nathalie Brandenberg have developed a method that uses a laser to cut three-dimensional pathways and networks for cells inside a hydrogel scaffold that matches their natural environment.
The method combines lasers with microfluidics – the science of controlling fluids in micrometer-sized spaces. Here, the scientists used focalized short-pulsed lasers, which can generate enough power to create tiny tunnels in different biocompatible gels already used in cell biology and tissue engineering. The laser can be applied before or even during 3D cell culture, meaning that the cells can be controlled in real time to match their natural growth.
Bioengineers determine textile manufacturing processes ideal for engineering tissues needed for organ and tissue repair
Tissue engineering is a process that uses novel biomaterials seeded with stem cells to grow and replace missing tissues.
When certain types of materials are used, the “scaffolds” that are created to hold stem cells eventually degrade, leaving natural tissue in its place. The challenge is creating enough of the material on a scale that clinicians need to treat patients.
Elizabeth Loboa, dean of the MU College of Engineering, and her team recently tested new methods to make the process of tissue engineering more cost effective and producible in larger quantities. Tissues could help patients suffering from wounds caused by diabetes and circulation disorders, patients in need of cartilage or bone repair and to women who have had mastectomies by replacing their breast tissue.
In a landmark proof-of-concept experiment, Australian researchers have used a handheld 3D printing pen to ‘draw’ human stem cells in freeform patterns with extremely high survival rates.
The device, developed out of collaboration between ARC Centre of Excellence for Electromaterials Science (ACES) researchers and orthopaedic surgeons at St Vincent’s Hospital, Melbourne, is designed to allow surgeons to sculpt customised cartilage implants during surgery.
Using a hydrogel bio-ink to carry and support living human stem cells, and a low powered light source to solidify the ink, the pen delivers a cell survival rate in excess of 97%.
3D bioprinters have the potential to revolutionise tissue engineering –they can be used to print cells, layer-by-layer, to build up artificial tissues for implantation.
But in some applications, such as cartilage repair, the exact geometry of an implant cannot be precisely known prior to surgery. This makes it extremely difficult to pre-prepare an artificial cartilage implant.
The Biopen special is held in the surgeon’s hands, allowing the surgeon unprecedented control in treating defects by filling them with bespoke scaffolds.
Professor Peter Choong, Director of Orthopaedics at St Vincent’s Hospital Melbourne, developed the concept with ACES Director Professor Gordon Wallace.
“The development of this type of technology is only possible with interactions between scientists and clinicians – clinicians to identify the problem and scientists to develop a solution,” Professor Choong said.
The team designed the BioPen with the practical constraints of surgery in mind and fabricated it using 3D printed medical grade plastic and titanium. The device is small, lightweight, ergonomic and sterilisable. A low powered light source is fixed to the device and solidifies the inks during dispensing.
“The biopen project highlights both the challenges and exciting opportunities in multidisciplinary research. When we get it right we can make extraordinary progress at a rapid rate,” Professor Wallace said.
Learn more: Handheld surgical ‘pen’ prints human stem cells
Researchers at U of T Engineering have developed a new way of growing realistic human tissues outside the body. Their “person-on-a-chip” technology, called AngioChip, is a powerful platform for discovering and testing new drugs, and could eventually be used to repair or replace damaged organs.
Professor Milica Radisic (IBBME, ChemE), graduate student Boyang Zhang and their collaborators are among those research groups around the world racing to find ways to grow human tissues in the lab, under conditions that mimic a real person’s body. They have developed unique methods for manufacturing small, intricate scaffolds for individual cells to grow on. These artificial environments produce cells and tissues that resemble the real thing more closely than those grown lying flat in a petri dish.
he team’s recent creations have included BiowireTM — an innovative method of growing heart cells around a silk suture — as well as a scaffold for heart cells that snaps together like sheets of Velcro™. But AngioChip takes tissue engineering to a whole new level. “It’s a fully three-dimensional structure complete with internal blood vessels,” says Radisic. “It behaves just like vasculature, and around it there is a lattice for other cells to attach and grow.” The work — which is published todayin the journal Nature Materials — was produced collaboratively with researchers from across U of T, including Professor Michael Sefton (ChemE, IBBME), Professor Aaron Wheeler (Chemistry, IBBME) and their research teams, as well as researchers from Toronto General Hospital and University Health Network.
Researchers in the United Kingdom and Malaysia are developing a new class of injectable material that stimulates stem cells to regenerate damaged tissue and form new blood vessels, heart and bone tissue.
Scientists at the University of Basel report first ever successful nose reconstruction surgery using cartilage grown in the laboratory.
Cartilage cells were extracted from the patient’s nasal septum, multiplied and expanded onto a collagen membrane. The so-called engineered cartilage was then shaped according to the defect and implanted. The results will be published in the current edition of the academic journal “The Lancet”.
A research team from the University of Basel in Switzerland has reported that nasal reconstruction using engineered cartilage is possible. They used a method called tissue engineering where cartilage is grown from patients’ own cells. This new technique was applied on five patients, aged 76 to 88 years, with severe defects on their nose after skin cancer surgery. One year after the reconstruction, all five patients were satisfied with their ability to breathe as well as with the cosmetic appearance of their nose. None of them reported any side effects.
Cells from the nasal septum
The type of non-melanoma skin cancer investigated in this study is most common on the nose, specifically the alar wing of the nose, because of its cumulative exposure to sunlight. To remove the tumor completely, surgeons often have to cut away parts of cartilage as well. Usually, grafts for reconstruction are taken from the nasal septum, the ear or the ribs and used to functionally reconstruct the nose. However, this procedure is very invasive, painful and can, due to the additional surgery, lead to complications at the site of the excision.
Together with colleagues from the University Hospital, the research team from the Department of Biomedicine at the University of Basel has now developed an alternative approach using engineered cartilage tissue grown from cells of the patients’ nasal septum. They extracted a small biopsy, isolated the cartilage cells (chondrocytes) and multiplied them. The expanded cells were seeded onto a collagen membrane and cultured for two additional weeks, generating cartilage 40 times the size of the original biopsy. The engineered grafts were then shaped according to the defect on the nostril and implanted.
New possibilities for facial reconstruction
According to Ivan Martin, Professor for Tissue Engineering at the Department of Biomedicine at the University and University Hospital of Basel, “The engineered cartilage had clinical results comparable to the current standard surgery. This new technique could help the body to accept the new tissue better and to improve the stability and functionality of the nostril. Our success is based on the long-standing, effective integration in Basel between our experimental group at the Department of Biomedicine and the surgical disciplines at the University Hospital. The method opens the way to using engineered cartilage for more challenging reconstructions in facial surgery such as the complete nose, eyelid or ear.”
The same engineered grafts are currently being tested in a parallel study for articular cartilage repair in the knee. Despite the optimistic perspectives, the use of these procedures in the clinical practice is still rather distant. “We need rigorous assessment of efficacy on larger cohorts of patients and the development of business models and manufacturing paradigms that will guarantee cost-effectiveness”, says Martin.
Meat grown using tissue engineering techniques, so-called ‘cultured meat’, would generate up to 96% lower greenhouse gas emissions than conventionally produced meat, according to a new study.
The analysis, carried out by scientists from Oxford University and the University of Amsterdam, also estimates that cultured meat would require 7-45% less energy to produce than the same volume of pork, sheep or beef. It would require more energy to produce than poultry but only a fraction of the land area and water needed to rear chickens.
A report of the team’s research is published in the journal Environmental Science & Technology.
‘What our study found was that the environmental impacts of cultured meat could be substantially lower than those of meat produced in the conventional way,’ said Hanna Tuomisto of Oxford University’s Wildlife Conservation Research Unit, who led the research. ‘Cultured meat could potentially be produced with up to 96% lower greenhouse gas emissions, 45% less energy, 99% lower land use, and 96% lower water use than conventional meat.’