Bioengineered skin and skin substitutes in wound management

Bioengineered skin was developed because of the need to cover extensive burn injuries in patients who no longer had enough skin for grafting. Not so long ago, a patient with third degree burns over 50% of his body surface usually died from his injuries. That is no longer the case. Today, even someone with 90% total body surface area burn has a good chance of surviving. With the array of bioengineered skin and skin substitutes available today, such products are also finding use for chronic wounds, in order to prevent infection, speed healing and provide improved cosmetic results.

Skin used in wound care may be autograft (from the patient’s own body, as is often the case with burn patients), allograft (cadaver skin), xenogeneic (from animals such as pigs or cows), or a combination of these. Bioengineered skin substitutes are synthetic, although they, too, may be combined with other products. It consists of an outer epidermal layer and (depending on the product) a dermal layer, which are embedded into an acellular support matrix. This product may be autogenic, or from other sources. Currently most commercial bioengineered skin is sheets of cells derived from neonatal allogenic foreskin. This source is chosen for several reasons: because the cells come from healthy newborns undergoing circumcision, and therefore the tissue would have been discarded anyway; foreskin tissue is high in epidermal keratinocyte stem cells, which grow vigorously; and because allergic reactions to this tissue is uncommon.

Bioengineered skin and skin substitutes are on the market and in development by LifeCell (Acelity), Organogenesis, Smith & Nephew, Organogenesis, Vericel Corporation (formerly Aastrom Biosciences), Mölnlycke Health Care, Integra LifeSciences, Smith & Nephew, Stratatech Corporation, A-Skin, University Children’s Hospital, Zurich; EuroSkinGraft.

The market may become more crowded as growth in the adoption of these products draws more competitors. Bioengineered skin and skin substitutes will drive more revenue than any other segment of the broader wound management market.

Growth in Advanced Wound Market Segments, 2014 to 2024

Competitors’ positions in bioengineered skin are variable based on their geographic presence. See shares in the U.S., the UK, and Germany for bioengineered skin & skin substitutes.

 

Source: MedMarket Diligence, LLC; Report #S251, “Wound Management to 2024.”

 

Source: MedMarket Diligence, LLC; Report #S251, “Wound Management to 2024.”

Source: MedMarket Diligence, LLC; Report #S251, “Wound Management to 2024.”

 

What is the ideal wound product?

The previously accepted wisdom was that a wound healed best when it was kept as dry as possible. In 1962, George Winter, a British-born physician, published his ground-breaking wound care research. His paper, (Nature 193:293. 1962), entitled, “Formation of the scab and the rate of epithelization of superficial wounds in the skin of the young domestic pig,” demonstrated that wounds kept moist healed faster than those exposed to the air or covered with a traditional dressing and kept dry. Dr. Winter’s work began the development of modern wound dressings which are used to promote moist wound healing.

Natural skin is considered the ideal wound dressing, and therefore wound dressings have been designed to try to reproduce the advantages of natural skin. Today, experts feel that a wound dressing should have several characteristics if it is to serve its purpose. A wound dressing should:

  • Provide the optimal moisture needs for the particular wound
  • Have the capacity to provide thermal insulation, gaseous exchange, and to help drainage and debris removal, which promotes tissue reconstruction
  • Be biocompatible without causing any allergic or immune response reaction
  • Protect the wound from secondary infections
  • Be easily removable without causing any trauma to the delicate healing tissues.

There are hundreds of dressings to choose from, but they all fall into one of a few categories. The healthcare provider will select a dressing by category, according to availability and familiarity of using that particular dressing.

Occlusive dressings are those which are air- and water-tight. An occlusive dressing is frequently made with some kind of waxy coating to ensure a totally water-tight bandage. It may also consist of a thin sheet of plastic affixed to the skin with tape. An occlusive dressing retains moisture, heat, body fluids and medication in the wound. There are several types of occlusive dressings, which are discussed below.

It should be remembered that proper wound care, especially of a chronic wound, is a complex process, as much art as science; a trained healthcare provider assesses the wound as it goes through various stages, and applies the appropriate wound dressings as the need arises. Unfortunately, the most appropriate dressing is not always used, due perhaps to confusion around which type of dressing to apply, or because certain dressings—especially advanced dressings—either may not be available in the facility, or may not be reimbursed by the country’s healthcare system, or may simply be too expensive. This remains true even in some of the developed countries.

The following table summarizes potential applications for various types of wound care products, with selected examples. This summary is meant as a guideline and an illustration of the fact that different dressing types may find use in various types of wounds. In addition, as a wound heals, it may need a different type of dressing. Here again the wound care professional’s judgment and training come into play.

Dressing categoryProduct examplesDescriptionPotential applications
FilmHydrofilm, Release, Tegaderm, BioclusiveComes as adhesive, thin transparent polyurethane film, and as a dressing with a low adherent pad attached to the film.Clean, dry wounds, minimal exudate; also used to cover and secure underlying absorptive dressing, and on hard-to-bandage locations, such as heel.
FoamPermaFoam, PolyMem, BiatainPolyurethane foam dressing available in sheets or in cavity filling shapes. Some foam dressing have a semipermeable, waterproof layer as the outer layer of the dressingFacilitates a moist wound environment for healing. Used to clean granulating wounds which have minimal exudate.
HydrogelHydrosorb Gel Sheet, Purilon, Aquasorb, DuoDerm, Intrasite Gel, Granugel,Colloids which consist of polymers that expand in water. Available in gels, sheets, hydrogel-impregnated dressings.Provides moist wound environment for cell migration, reduces pain, helps to rehydrate eschar. Used on dry, sloughy or necrotic wounds.
HydrocolloidCombiDERM, Hydrocoll, Comfeel, DuoDerm CGF Extra Thin, Granuflex, TegasorbÕ Nu-DermMade of hydroactive or hydrophilic particles attached to a hydrophobic polymer. The hydrophilic particles absorb moisture from the wound, convert it to a gel at the interface with the wound. Conforms to wound surface; waterproof and bacteria proof.Gel formation at wound interface provides moist wound environment. Dry necrotic wounds, or for wounds with minimal exudate. Also used for granulating wounds.
AlginateAlgiSite, Sorbalgon Curasorb, Kaltogel, Kaltostat, SeaSorb, TegagelA natural polysaccharide derived from seaweed; available in a range of sizes, as well as in ribbons and ropes.Because highly absorbent, used for wounds with copious exudate. Can be used in rope form for packing exudative wound cavities or sinus tracts.
AntimicrobialBiatain Ag, Atrauman Ag, MediHoneyBoth silver and honey are used as antimicrobial elements in dressings.Silver: Requires wound to be moderately exudative to activate the silver, in order to be effective
NPWDSNaP, V.A.C. Ulta, PICO, Renasys (not in USA), Prospera PRO series, Invia LibertyComputerized vacuum device applies continuous or intermittent negative or sub-atmospheric pressure to the wound surface. NPWT accelerates wound healing, reduces time to wound closure. Comes in both stationary and portable versions.May be used for traumatic acute wound, open amputations, open abdomen, etc. Seems to increase burn wound perfusion. Also used in management of DFUs. Contraindicated for arterial insufficiency ulcers. Not to be used if necrotic tissue is present in over 30% of the wound.
Bioengineered Skin and Skin SubstitutesAlloDerm, AlloMax, FlexHD, DermACELL, DermaMatrix, DermaPure, Graftjacket Regenerative Tissue Matrix, PriMatrix, SurgiMend PRS, Strattice Reconstructive Tissue Matrix, Permacol, EpiFix, OASIS Wound Matrix, Apligraf, Dermagraft, Integra Dermal Regeneration Template, TransCyteBio-engineered skin and soft tissue substitutes may be derived from human tissue (autologous or allogeneic), xenographic, synthetic materials, or a composite of these materials.Burns, trauma wounds, DFUs, VLUs, pressure ulcers, postsurgical breast reconstruction, bullous diseases

Source: MedMarket Diligence, LLC; Report #S251.

Bioengineered skin displacing traditional wound management products

Very decided shifts are taking place in the wound management market as advanced wound technologies take up caseload from traditional technologies like gauze and others. It becomes evident that traditional products once representing above average sales are now projected to be below average (gauze) as are even a moderately new technology, “negative pressure wound therapy devices” (NPWD), while bioengineered skin and skin substitutes will represent “above average”.

Global Wound Management Market,
Above/Below Average Sectors, 2015 & 2024

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Source: Report #S251.

Global Wound Management Market, Sales, 2015 & 2024

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Source: Report #S251.

Despite the tepid growth of traditional wound management products, they remain very large markets that even the most aggressively growing segments will require time to match that volume. Bioengineered skin and skin substitutes are moving fast in that direction.

Global CAGR 2016-2024 for Wound Management Segments

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Source: Report #S251.

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