Novel combination therapy promotes wound healing

Mouse skin was burned and treated with either a standard burn treatment or new wound-healing therapy. After two weeks, cross sections of burned skin show control skin (top image) had clearly not healed, with no hair follicles, sebaceous glands or other higher order structures present in the burn area. Burns treated with therapeutic gel (bottom image) showed progressive healing and tissue regeneration, including new hair follicles. Credit: Sharp Lab/Albert Einstein College of Medicine

By incorporating a gene-suppressing drug into an over-the-counter gel, researchers at Albert Einstein College of Medicine and their colleagues cut healing time by half and significantly improved healing outcomes compared to control treatments. Results from the combination therapy, which was tested in mice, were published online today in Advances in Wound Care.

28 oct 2018--"Not only did wound healing occur more rapidly and completely, but actual regeneration occurred, with hair follicles and the skin's supportive collagen network restored in wounded skin—clinically important improvements that are unprecedented in wound care," says senior author David J. Sharp, Ph.D, professor of physiology & biophysics at Einstein. "We foresee this therapy having broad application for all sorts of wounds, from playground cuts to battlefield injuries to chronic wounds."
Chronic wounds alone affect 6.5 million Americans and cost $25 billion in annual healthcare costs. Over the past several decades, few advances have been made in treating wounds of any type.
In 2015, Dr. Sharp and colleagues discovered that an enzyme called fidgetin-like 2 (FL2) puts the brakes on skin cells as they migrate towards wounds to heal them. He reasoned that reducing FL2 levels might enable healing cells to reach their destination faster. So he and his colleagues developed small interfering RNA molecules (siRNAs) that specifically inhibit the gene that codes for FL2. When the siRNAs were encased in nanoparticles and sprayed on skin wounds in mice, the treated wounds healed faster than untreated wounds.
In the current study, Dr. Sharp enhanced the siRNAs' wound-healing potential by combining them with PluroGel—a protective gel that keeps wounds moist and has antimicrobial properties when applied to bandages and other wound dressings. In addition, Dr. Sharp incorporated the siRNAs into microparticles made of collagen, a naturally occurring protein that readily releases its siRNA "cargo" after coming in contact with the skin.
The FL2-siRNA/PluroGel combination was applied to mice with either skin excisions or burns. For comparison, studies involving both types of skin injuries also used two control groups: mice treated with PluroGel alone and mice treated with PluroGel plus siRNA that did not target the gene for FL2. Wounds were treated on the day of the skin excision or burn and again two, four and six days later. For 14 days following the injuries, wounds were assessed by investigators who were "blinded" as to the treatment the mice received.
On the fourth day after mice treated for excision wounds, the open wound areas of mice in the two control groups were nearly twice as large as the wound areas in mice treated with the FL2-siRNA/PluroGel combination. Several mice treated with the combination therapy also had hair follicles present in the wound zone, while no such structures were seen in the control mice.
For mice treated for burns: by 14-days post injury, the wounds of mice in both control groups were more than one-third larger than in the mice treated with the FL2-siRNA/PluroGel combination. In addition, the burn wounds of all mice treated with the FL2-siRNA/PluroGel combination had closed completely by day 14; by comparison, 25 percent and 30 percent of treated wounds in the PluroGel and PluroGel/nontarget siRNA control groups, respectively, remained unhealed at that time.
"These results show that FL2-siRNA plus PluroGel is a highly promising wound treatment," says Adam Kramer, a Ph.D. candidate in Dr. Sharp's lab and co-lead author. "By lowering FL2 levels in skin cells, the FL2-siRNA helps cells reach wound sites much faster than they ordinarily would—essential for minimizing scarring and preventing wounds from becoming chronic. And by hydrating wounds and inhibiting microbes, PluroGel offers important additional wound-healing benefits."
Dr. Sharp and Brian O'Rourke, Ph.D., the paper's co-lead author and chief scientist at MicroCures, Inc., have achieved similar success in treating skin wounds in pigs—animals with skin that closely resembles human skin. Dr. Sharp's team plans to seek permission from the U.S. Food and Drug Administration to test their wound-healing therapy in clinical trials.
The paper is titled "Fidgetin-like 2 siRNA Enhances the Wound Healing Capability of a Surfactant Polymer Dressing."


Provided by Albert Einstein College of Medicine

Forcing wounds to close

Forces exerted by the cells surrounding the gap (dotted blue line) extend away at first, then direct inwards, towards the gap, during contraction of the 'purse-string' cable (red filaments).

A collaborative study led by scientists from the Mechanobiology Institute (MBI) at the National University of Singapore (NUS) has revealed the mechanical forces that drive epithelial wound healing in the absence of cell supporting environment. This research was published in Nature Communications in January 2015.

Sealing the gaps

10 feb 2015--Skin not only provides an essential protective barrier against foreign materials and pathogens, but it also helps the body retain various fluids and electrolytes. When this barrier is damaged, the consequences can be devastating. Ulcers, bleeding and bacterial infections may result and the chances of these occurring increases the longer wounds remain open.

Fortunately, epithelial cell sheets are self-repairing. The moment the integrity of the barrier is compromised, cellular mechanisms are initiated to close the gap. Cells begin crawling forward, and contractile cables are formed in the cells surrounding the wound to help pull the gap close. For several years, scientists have been learning much about how cells coordinate these processes and repair wounds quickly. In most cases, the healthy skin cells responsible for carrying out wound repair rely on a supporting layer underneath them. This layer comprises sticky proteins, and is known as the extracellular matrix (ECM), which provides support for them to adhere to and crawl over.

However, in cases of chronic or severe wounds, the underlying layers could also be damaged. Surrounding cells could also be unable to replace the ECM proteins. Yet the repair of these gaps, known as non-adherent gaps, does occur, albeit at a slower rate and with an increased likelihood of infection or other complications. So the question remained; how do cells close gaps in protective epithelial barriers where the underlying layers are also damaged or the ECM eroded?

This question was the focus of a study led by MBI Principal Investigator (PI) Professor Chwee Teck Lim and Co-Principal Investigator Professor Benoit Ladoux, along with MBI PI Assistant Professor Yusuke Toyama. Their findings reveal that closure of non-adherent gaps is driven exclusively by 'purse-string contraction'. Using a combination of cell culture, microfabrication and force measurements, the scientists discovered that a cellular 'tug-of-war' at the gap edge drives the mechanical forces responsible for gap closure.

The cells at the edge of the non-adherent gap are still attached to the ECM. These cells then spread themselves out as far as possible towards the centre of the gap. Measuring the direction of force revealed that these cells are actually pushing away from the gap. While this may sound counter-intuitive, it actually stabilises the cells, in a similar manner to a cantilever bridge, where support at either end anchors the extension of the bridge into space until two sides eventually meet in the middle. Once the cells have spread as far as possible into the gap, the contractile 'purse-string' cable forms across the cells, encircling the gap. The force exerted by these cells is reversed and the cells begin to pull each other towards the centre of the gap, continually speeding up the contraction of the protein cable. As the cells move inwards to close the empty space, more contractile cables can reach out over the gap and connect to the other side. These cables can contract rapidly, leading to the formation of a suspended cell sheet over the gap, and complete closure of the wound.

The 'tug-of-war' mechanism identified in this study provides a vivid demonstration of how cells exert directional forces to enhance biological processes. This new knowledge of the mechanical properties of skin and internal epithelial cells may lead to advances in wound repair, especially in cases where the ECM is compromised. With chronic wounds, sores and ulcers being a common complication in several diseases, particularly those associated with aging, it is imperative that researchers better understand the mechanisms at play in their repair. This will undoubtedly lead to improved treatments in wound healing.

More information: Vedula et al., Mechanics of epithelial closure over non-adherent environments, Nature Communications, 22 Jan 2015, DOI: 10.1038/ncomms7111

Provided by National University of Singapore

Patients should ask surgeons about using honey to heal wounds

Surgeons are being advised to consider the supermarket as well as the drugs cupboard when it comes to effective wound healing, according to a research review published in the October issue of IJCP, the International Journal of Clinical Practice.
And patients who’ve undergone surgery should ask their doctors whether they should apply honey to their wounds to speed up healing and reduce infection.
“Honey is one of the oldest foods in existence and was an ancient remedy for wound healing” explains lead author Dr Fasal Rauf Khan from North West Wales NHS Trust in Bangor. “It was found in the tomb of King Tutankhamun and was still edible as it never spoils.”
Honey is enjoying a revival as more reports of its effectiveness are published, he adds.
“Researchers started to document the wound healing properties of honey in the early 20th century, but the introduction of antibiotics in 1940 temporarily halted its use.
“Now concerns about antibiotic resistance, and a renewed interest in natural remedies, has prompted a resurgence in the antimicrobial and wound healing properties of honey.
“Honey has a number of properties that make it effective against bacterial growth, including its high sugar content, low moisture content, gluconic acid – which creates an acidic environment – and hydrogen peroxide. It has also been shown to reduce inflammation and swelling.”
Researchers have also reported that applying honey can be used to reduce amputation rates among diabetes patients.
Stressing that patients should always check with their surgeon before applying any substance to post-operative wounds, Dr Khan adds that studies have found that honey offers a number of benefits.
“It can be used to sterilise infected wounds, speed up healing and impede tumours, particularly in keyhole surgery.”
Studies have suggested that honey should be applied at regular intervals, from hourly to twice daily and that wounds can become sterile in three to 10 days.
“The research suggests that honey seems to be especially indicated when wounds become infected or fail to close or heal” says Dr Khan. “It is probably even more useful for healing the wounds left by laparoscopic surgery to remove cancers.”
18 studies covering more than 60 years were included in the review. The authors also looked at other substances used for wound healing, including maggots, which were also commonly used before the introduction of antibiotics and are enjoying a revival.
The team also discovered an ancient manuscript that used wine dregs, juniper prunes and beer, but point out that that has not been tried and tested in recent years!
“Our research suggests that surgeons should seriously consider using honey for post-operative wounds and offer this to patients” concludes Dr Khan. “We would also encourage patients to ask about honey as an option, but stress that they should always follow their surgeon’s advice and not try any home remedies.”