Penn researchers help break ground on method to transform cells
Doctors have found a way to manipulate wounds to heal as regenerated skin rather than scar tissue. The method involves transforming the most common type of cells found in wounds into fat cells – something that was previously thought to be impossible in humans. Researchers began this work at the Perelman School of Medicine at the University of Pennsylvania, which led to a large-scale, multi-year study in connection with the Plikus Laboratory for Developmental and Regenerative Biology at the University of California, Irvine. They published their findings online in the journal Science on Thursday, January 5th, 2017.
Fat cells called adipocytes are normally found in the skin, but they’re lost when wounds heal as scars. The most common cells found in healing wounds are myofibroblasts, which were thought to only form a scar. Scar tissue also does not have any hair follicles associated with it, which is another factor that gives it an abnormal appearance from the rest of the skin. Researchers used these characteristics as the basis for their work – changing the already present myofibroblasts into fat cells that do not cause scarring.
“Essentially, we can manipulate wound healing so that it leads to skin regeneration rather than scarring,” said George Cotsarelis, MD, the chair of the Department of Dermatology and the Milton Bixler Hartzell Professor of Dermatology at Penn, and the principal investigator of the project. “The secret is to regenerate hair follicles first. After that, the fat will regenerate in response to the signals from those follicles.”
The study showed hair and fat develop separately but not independently. Hair follicles form first, and the Cotsarelis lab previously discovered factors necessary for their formation. Now they’ve discovered additional factors actually produced by the regenerating hair follicle to convert the surrounding myofibroblasts to regenerate as fat instead of forming a scar. That fat will not form without the new hairs, but once it does, the new cells are indistinguishable from the pre-existing fat cells, giving the healed wound a natural look instead of leaving a scar.
As they examined the question of what was sending the signal from the hair to the fat cells, researchers identified a factor called Bone Morphogenetic Protein (BMP). It instructs the myofibroblasts to become fat. This signaling was groundbreaking on its own, as it changed what was previously known about myofibroblasts.
“Typically, myofibroblasts were thought to be incapable of becoming a different type of cell,” Cotsarelis said. “But our work shows we have the ability to influence these cells, and that they can be efficiently and stably converted into adipocytes.” This was shown in both the mouse and in human keloid cells grown in culture.
“The findings show we have a window of opportunity after wounding to influence the tissue to regenerate rather than scar,” said the study’s lead author Maksim Plikus, PhD, an assistant professor of Developmental and Cell Biology at the University of California, Irvine. Plikus began this research as a postdoctoral fellow in the Cotsarelis Laboratory at Penn, and the two institutions have continued to collaborate.
These discoveries have the potential to be revolutionary in the field of dermatology. The first and most obvious use would be to develop a therapy that signals myofibroblasts to convert into adipocytes – helping wounds heal without scarring.
“It’s highly desirable from a clinical standpoint, but right now it’s an unmet need,” Cotsarelis said.
But the increase of fat cells in tissue can also be helpful for more than just wounds. Adipocyte loss is a common complication of other conditions, especially treatments for HIV, and right now there is no efficient strategy for treatment. The cells are also lost naturally because of the aging process, especially in the face, which leads to permanent, deep wrinkles, something anti-aging treatments can’t fix in a cosmetically satisfactory way.
“Our findings can potentially move us toward a new strategy to regenerate adipocytes in wrinkled skin, which could lead us to brand new anti-aging treatments,” Cotsarelis said.
The Cotsarelis Lab is now focusing on the mechanisms that promote skin regeneration, especially with respect to hair follicle regeneration.
The Plikus Laboratory is focusing on other aspects of cell reprogramming in skin wounds. Researchers there are examining the role of other signaling factory beyond BMP as well as conducting further studies using human cells and human scar tissue.
Learn more: Using Fat to Help Wounds Heal Without Scars
A chance meeting between a spider expert and a chemist has led to the development of antibiotic synthetic spider silk.
After five years’ work an interdisciplinary team of scientists at The University of Nottingham has developed a technique to produce chemically functionalised spider silk that can be tailored to applications used in drug delivery, regenerative medicine and wound healing.
The Nottingham research team has shown for the first time how ‘click-chemistry’ can be used to attach molecules, such as antibiotics or fluorescent dyes, to artificially produced spider silk synthesised by E.coli bacteria. The research, funded by the Biotechnology and Biological Sciences Research Council (BBSRC) has been published in the online journal Advanced Materials.
The chosen molecules can be ‘clicked’ into place in soluble silk protein before it has been turned into fibres, or after the fibres have been formed. This means that the process can be easily controlled and more than one type of molecule can be used to ‘decorate’ individual silk strands.
In a laboratory in the Centre of Biomolecular Sciences, Professor Neil Thomas from the School of Chemistry in collaboration with Dr Sara Goodacre from the School of Life Sciences, has led a team of BBSRC DTP-funded PhD students starting with David Harvey who was then joined by Victor Tudorica, Leah Ashley and Tom Coekin. They have developed and diversified this new approach to functionalising ‘recombinant’ — artificial — spider silk with a wide range of small molecules.
They have shown that when these ‘silk’ fibres are ‘decorated’ with the antibiotic levofloxacin it is slowly released from the silk, retaining its anti-bacterial activity for at least five days.
Neil Thomas, a Professor of Medicinal and Biological Chemistry, said: “Our technique allows the rapid generation of biocompatible, mono or multi-functionalised silk structures for use in a wide range of applications. These will be particularly useful in the fields of tissue engineering and biomedicine.”
Remarkable qualities of spider silk
Spider silk is strong, biocompatible and biodegradable. It is a protein-based material that does not appear to cause a strong immune, allergic or inflammatory reaction. With the recent development of recombinant spider silk, the race has been on to find ways of harnessing its remarkable qualities.
The Nottingham research team has shown that their technique can be used to create a biodegradable mesh which can do two jobs at once. It can replace the extra cellular matrix that our own cells generate, to accelerate growth of the new tissue. It can also be used for the slow release of antibiotics.
Professor Thomas said: “There is the possibility of using the silk in advanced dressings for the treatment of slow-healing wounds such as diabetic ulcers. Using our technique infection could be prevented over weeks or months by the controlled release of antibiotics. At the same time tissue regeneration is accelerated by silk fibres functioning as a temporary scaffold before being biodegraded.”
The medicinal properties of spider silk recognised for centuries.
The medicinal properties of spider silk have been recognised for centuries but not clearly understood. The Greeks and Romans treated wounded soldiers with spider webs to stop bleeding. It is said that soldiers would use a combination of honey and vinegar to clean deep wounds and then cover the whole thing with balled-up spider webs.
There is even a mention in Shakespeare’s Midsummer Night’s Dream: “I shall desire you of more acquaintance, good master cobweb,” the character ‘Bottom’ said. “If I cut my finger, I shall make bold of you.”
‘I think we could make that!’
The idea came together at a discipline bridging university ‘sandpit’ meeting five years ago. Dr Goodacre says her chance meeting at that event with Professor Thomas proved to be one of the most productive afternoons of her career.
Dr Goodacre, who heads up the SpiderLab in the School of Life Sciences, said: “I got up at that meeting and showed the audience a picture of some spider silk. I said ‘I want to understand how this silk works, and then make some.’
“At the end of the session Neil came up to me and said ‘I think my group could make that.’ He also suggested that there might be more interesting ‘tweaks’ one could make so that the silk could be ‘decorated’ with different, useful, compounds either permanently or which could be released over time due to a change in the acidity of the environment.”
The approach required the production of the silk proteins in a bacterium where an amino acid not normally found in proteins was included. This amino acid contained an azide group which is widely used in ‘click’ reactions that only occur at that position in the protein. It was an approach that no-one had used before with spider silk — but the big question was — would it work?
Dr Goodacre said: “It was the start of a fascinating adventure that saw a postdoc undertake a very preliminary study to construct the synthetic silks. He was a former SpiderLab PhD student who had previously worked with our tarantulas. Thanks to his ground work we showed we could produce the silk proteins in bacteria. We were then joined by David Harvey, a new PhD student, who not only made the silk fibres, incorporating the unusual amino acid, but also decorated it and demonstrated its antibiotic activity. He has since extended those first ideas far beyond what we had thought might be possible.”
David Harvey’s work is described in this paper but Professor Thomas and Dr Goodacre say this is just the start. There are other joint SpiderLab/Thomas lab students working on uses for this technology in the hope of developing it further.
David Harvey, the lead author on this their first paper, has just been awarded his PhD and is now a postdoctoral researcher on a BBSRC follow-on grant so is still at the heart of the research. His current work is focused on driving the functionalised spider silk technology towards commercial application in wound healing and tissue regeneration.
Where will we be in 5 years’ time?
Dr Goodacre said: “It is likely that this paper is just the start of a very exciting range of studies using the new spider silk material. Some of the future work will also be supported by other, neat ideas from the world of spiders and their silk, which the SpiderLab is currently trying to unravel.”
People with diabetes often suffer from wounds that are slow to heal and can lead to ulcers, gangrene and amputation. New research from an international group led by Min Zhao, professor of ophthalmology and of dermatology at the University of California, Davis, shows that, in animal models of diabetes, slow healing is associated with weaker electrical currents in wounds. The results could ultimately open up new approaches for managing diabetic patients.
“This is the first demonstration, in diabetic wounds or any chronic wounds, that the naturally occurring electrical signal is impaired and correlated with delayed healing,” Zhao said. “Correcting this defect offers a totally new approach for chronic and nonhealing wounds in diabetes.”
It has been estimated that as much as $25 billion a year is spent on treating chronic ulcers and wounds related to diabetes, Zhao said.
Electric fields and wound healing
Electric fields are associated with living tissue. Previous work by Zhao and Brian Reid, project scientist at the UC Davis Department of Dermatology, showed that electric fields are associated with healing damage to the cornea, the transparent outer layer of the eye.
In the new work, published June 10 in the journal Scientific Reports, Zhao, Reid and colleagues used a highly sensitive probe to measure electrical fields in the corneas of isolated eyes from three different lab mouse models with different types of diabetes: genetic, drug-induced and in mice fed a high-fat diet.
In a healthy eye, there is an electrical potential across the thickness of the cornea. Removing a small piece of cornea collapses this potential and creates electric currents, especially at the edges of the wound. Cells migrate along the electric currents, closing the scratch wound in about 48 hours.
A multidisciplinary research team discovers how cells know to rush to a wound and heal it — opening the door to new treatments for diabetes, heart disease and cancer
Researchers at the University of Arizona have discovered what causes and regulates collective cell migration, one of the most universal but least understood biological processes in all living organisms.
The findings, published in the March 13, 2015, edition of Nature Communications, shed light on the mechanisms of cell migration, particularly in the wound-healing process. The results represent a major advancement for regenerative medicine, in which biomedical engineers and other researchers manipulate cells’ form and function to create new tissues, and even organs, to repair, restore or replace those damaged by injury or disease.
“The results significantly increase our understanding of how tissue regeneration is regulated and advance our ability to guide these processes,” said Pak Kin Wong, UA associate professor of mechanical and aerospace engineering and lead investigator of the research.
“In recent years, researchers have gained a better understanding of the molecular machinery of cell migration, but not what directs it to happen in the first place,” he said. “What, exactly, is orchestrating this system common to all living organisms?”
Leaders of the Pack
The answer, it turns out, involves delicate interactions between biomechanical stress, or force, which living cells exert on one another, and biochemical signaling.
The UA researchers discovered that when mechanical force disappears — for example at a wound site where cells have been destroyed, leaving empty, cell-free space — a protein molecule, known as DII4, coordinates nearby cells to migrate to a wound site and collectively cover it with new tissue. What’s more, they found, this process causes identical cells to specialize into leader and follower cells. Researchers had previously assumed leader cells formed randomly.
Wong’s team observed that when cells collectively migrate toward a wound, leader cells expressing a form of messenger RNA, or mRNA, genetic code specific to the DII4 protein emerge at the front of the pack, or migrating tip. The leader cells, in turn, send signals to follower cells, which do not express the genetic messenger. This elaborate autoregulatory system remains activated until new tissue has covered a wound.
The same migration processes for wound healing and tissue development also apply to cancer spreading, the researchers noted. The combination of mechanical force and genetic signaling stimulates cancer cells to collectively migrate and invade healthy tissue.
Biologists have known of the existence of leader cells and the DII4 protein for some years and have suspected they might be important in collective cell migration. But precisely how leader cells formed, what controlled their behavior, and their genetic makeup were all mysteries — until now.
Broad Medical Applications
“Knowing the genetic makeup of leader cells and understanding their formation and behavior gives us the ability to alter cell migration,” Wong said.
With this new knowledge, researchers can re-create, at the cellular and molecular levels, the chain of events that brings about the formation of human tissue. Bioengineers now have the information they need to direct normal cells to heal damaged tissue, or prevent cancer cells from invading healthy tissue.