the use of objectives epidermal/dermal cme1.pdfallows for a break in the continuity and integrity of...

NOVEMBER/DECEMBER 2007 • PODIATRY MANAGEMENTwww.podiatrym.com 171

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proved and are marketed for a varietyof clinical and surgical applications.2

Treatment with the grafts reviewedin this article should be considered inconjunction with standard of caretreatments for wounds, and not as asubstitute for these principles. In orderfor a wound healing stimulant to be

Continued on page 172

IntroductionChronic wounds reflect a failure

to achieve the normal processes re-quired for healing. The deviationfrom normal wound healing canoccur with hemostasis, inflamma-tion, proliferation, epithelization, or

tissue remodeling for any number ofreasons, resulting in a chronicwound.1 Therefore, there is a strongneed for effective treatments that re-verse the physiological deficienciesfound with chronic wounds. Thereare currently a wide array of dermalreplacement and combined replace-ment matrices that have been ap-

By Linnie V. Rabjohn, DPM

Welcome to Podiatry Management’s CME Instructional program. Our journal has been approved as a sponsor of Contin-uing Medical Education by the Council on Podiatric Medical Education.

You may enroll: 1) on a per issue basis (at $20.00 per topic) or 2) per year, for the special introductory rate of $139 (yousave $61). You may submit the answer sheet, along with the other information requested, via mail, fax, or phone. In the nearfuture, you may be able to submit via the Internet.

If you correctly answer seventy (70%) of the questions correctly, you will receive a certificate attesting to your earned cred-its. You will also receive a record of any incorrectly answered questions. If you score less than 70%, you can retake the test atno additional cost. A list of states currently honoring CPME approved credits is listed on pg. <None>. Other than those entitiescurrently accepting CPME-approved credit, Podiatry Management cannot guarantee that these CME credits will be acceptableby any state licensing agency, hospital, managed care organization or other entity. PM will, however, use its best efforts to en-sure the widest acceptance of this program possible.

This instructional CME program is designed to supplement, NOT replace, existing CME seminars. Thegoal of this program is to advance the knowledge of practicing podiatrists. We will endeavor to publish high quality manuscriptsby noted authors and researchers. If you have any questions or comments about this program, you can write or call us at: PodiatryManagement, P.O. Box 490, East Islip, NY 11730, (631) 563-1604 or e-mail us at [email protected].

An answer sheet and full set of instructions are provided on pages 252-254.—Editor

These modalities can be effective for chronic diabetic foot and venous ulcerations.

Objectives1) To understand the

different characteristicsof dermal and epider-mal grafts available foruse on both venous andchronic ulcerations.

2) To be able to de-fine a living skin equiv-alent.

3) To understand theapplication processes ofthe various grafts avail-able for ulceration coverage.

4) To understand the environment of achronic ulceration.

The Use ofEpidermal/DermalReplacementTherapies andCombinedReplacementMatrices

The Use ofEpidermal/DermalReplacementTherapies andCombinedReplacementMatrices

considered effec-tive, no matter the

composition of cells,growth factors, or grafts,

it must interact with thehost’s cells, persist for a sig-nificant period of time, andalso colonize the wound.3 Avariety of wound healingpromoting agents have be-come available in the medi-cal community.

Epidermal and/or der-mal substitutes are consid-ered a subset of theseagents. Some are composedof living, healthy cells thatpromote healing by pro-ducing the necessary com-ponents for the healingprocess. Others are composed of var-ied tissue matrices that allow and pro-mote the in-growth of the host’s cellsto heal the deficit. Each one poses ad-vantages and specifications differentfrom the others, making the under-standing of the different substitutescomplex. This re-view does not takea position of pro-moting or market-ing one substituteover another;rather it makesavailable some in-formation aboutthe more com-monly used grafts.The decision toapply a specificgraft should bebased on the indi-vidual patient, aseach substitute of-fers a different ap-proach to promote wound healing.The treatment of a wound must takeinto account the etiology, depth, andthe surface area as different types ofwounds may need different treat-ments and do not share the sameprognosis.4

A Review of Healing and Non-healing Wounds

The skin is the largest organ ofthe body and its responsibilities arevast and important. Skin provides adefense against infection, regulatesbody temperature, and prevents de-hydration, along with providing sen-

sation.4 The presence of an ulcerationallows for a break in the continuityand integrity of this vital organ. Un-derlying pathologies make an indi-vidual more prone to the develop-ment of a wound, making the etiolo-gies of developing wounds vast. The

epidermal layer ofskin is composedof proliferatingk e r a t i n o c y t e s ,which are com-posed of proteinsthat provide thestructure of skin.The deeper, dermallayer is a thick ex-tracellular matrixwhich houses fi-broblasts. Thislayer provides thestrength and elas-ticity of skin andhouses the bloodvessels, lymphatic

channels, and nerves.Ulcerations lack the normal

skin barrier necessary to protect aperson from bacterial infectionswhich can lead to sepsis.5 The ab-sent barrier allows for loss of water,proteins, and energy. Chronicwounds have been defined as thosethat have been arrested in a state ofinflammation with an imbalance ofprotease activity and growth factorexpression.3 There is also a loss ofcell motility and migration, as thekeratinocytes are present at the pe-riphery of the wound but fail tomove around.6 Fibroblasts in a

chronic wound lose their ability toproliferate and form the matrix, orscaffold, for repair.7

In chronic wounds there hasbeen a departure from the normalcascade of wound healing events.The three phases of wound healingare the inflammatory phase, re-ep-


172 www.podiatrym.comPODIATRY MANAGEMENT • NOVEMBER/DECEMBER 2007

Figure 2: The same patient with PVD after oneapplication of Apligraf. Note the granular tissuepresent adjacent to the anterior tibial tendon.The anterior tibial tendon remains viable.

Figure 3: The same severe PVD patientwith plantar arterial ulceration that hasbeen present for over one year and isvery painful with ambulation.

Figure 1: This is the initial photo of an anteriorankle ulcer in a patient with severe PVD. This pa-tient is not a candidate for revascularization. Theulcer occurred secondary to a surgical dissectionthat dehisced. The ulcer has been present foreight months, and after debridement of thenecrotic tissue, it has exposed the anterior tibialistendon which is viable.

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Figure 4: The same severe PVD patientwith a healed plantar arterial ulcerationafter one application of Apligraf.

The decision to apply

a specific graft should

be based on the

individual patient, as

each substitute offers

a different approach

to promote wound

healing.


functions. These functions includeproducing and depositing the extra-cellular matrix which allows for thein-growth of blood vessels and skincells.10 Fibroblasts also multiply andmove to the wound area in responseto chemotactic, mitogenic activity,and certain cytokines that resultfrom injury to the skin layers. A pre-vious study has shown that fibrob-last density within a wound plays acrucial role in the development ofnormal epidermal morphology anddifferentiation of keratinocytes.11

Therefore, for a dressing to be con-sidered effective, the optimal densityof fibroblasts must be established.The formation of the basementmembrane also depends on fibrob-lasts that induce collagen and the se-cretion of cytokines.2

Cytokines then stimulate ker-atinocytes to form the basementmembrane of skin. The formationof new blood vessels and lymphaticchannels depends on fibroblastsalso. Culturing fibroblasts for cer-tain wound dressings can augmentthe wound healing process by plac-ing these cells in a chronic woundthat may have been deficient andfor that reason is arrested in a non-healing state.

The ideal synthetic wounddressing or skin equivalent has thefollowing qualities: absence of anti-

ithelization phase, and the tissueremodeling phase. These threephases of wound healing are notseparate and distinct, but overlap.Neutrophils, macrophages, andplatelets are the predominate cellsfound in the wound during the in-flammatory phase, the initial phaseof wound healing. Within the firstfour days, these cells migrate to thewound site in a response to injury.8

They are also responsible for theinitiation of smooth muscle con-traction and for cleaning thewound of debris. The production ofnecessary growth factors is attribut-ed to these inflammatory cells andto fibroblasts. This stimulates epi-dermal regeneration and revascular-ization that occur during the lasttwo phases of wound healing.9 Fi-broblasts alone produce a variedcomposition of cytokines that in-clude growth factors, interleukins,and angiogenic factors.1

In discussing wound healing, un-derstanding the role of fibroblastscan be crucial in order to understandthe role of the available wound heal-ing agents. Fibroblasts are a popula-tion of heterogenous cells that canbe found in a variety of tissues.2 Fi-broblasts that reside in the dermalcomponents of skin have numerous

Therapies... genicity, compatibilitywith a variety of wounds,lack of toxicity, impermeabili-ty to bacteria, adherence to thesurface, elasticity to allow motion,and the ability to transfer wateracross the dressing.4 The use ofsuch grafts can result in an expenseoften passed to the patient or insur-ance company, so while expensive,they can provide a worthy benefit.The shelf-life of such grafts is alsoan important factor. Some must beordered within days of applicationfor the graft to be usable.

Diabetic foot ulcerations (DFU)can compromise the health of a pop-ulation of patients already faced withmedical concerns. They may signifi-cantly impair the quality of life andcan result in not only prolonged hos-pital admissions, but also major lowerextremity amputations.12 The longeran ulceration is allowed to persist, thegreater the possibility that bacterialinfection will occur and the higherthe risk for amputation.13

Complications that occur withdiabetes mellitus (DM) include pe-ripheral neuropathy, macrovascularand microvascular changes, im-munological deficiencies, and ac-quired deformities. These factorsstrongly influence the developmentof ulceration in addition to leadingto the failure of a wound to heal. Di-abetes imparts pathological changesthat can lead to changes in the ex-pression of growth factors, impairedfibroblast function, a decrease in im-munologic function, and deficits inthe extracellular matrix.4 An abnor-mality in the expression of cy-tokines and growth factors necessaryfor healing a wound occurs.14,15

Ulcer recurrence is a commonconcern with diabetic patients.16 Astrong predicting factor for the devel-opment of an ulceration is a patient’sown history of previous ulceration.Therefore, it is essential that the med-ical community not only search outpossible mechanisms to increase therate of healing but also those that de-crease recurrence. In order to obtainthe most advantageous results withuse of grafts, the physician must firstreview the overall health of the dia-betic in terms of glucose control,compliance with treatment, bacterialload, and the ability to offload thewound of concern.


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TABLE 1

Wagner Classification System to Rate the Severity

of Diabetic Foot Ulcerations

Grade 0: Pre-ulcerative lesions, healed ulcer scars, presence of osseous deformity which leads to unguarded pressure.

Grade 1: Superficial partial or full thickness ulcerations, notincluding

tendon, capsule, or bone.

Grade 2: Ulceration involving subcutaneous tissue that can have exposed tendon or igament, but not bone.

Grade 3: Ulceration that has exposed bone, or probes to bone.

Grade 4: Gangrene of the forefoot.

Grade 5: Gangrene of entire foot.

Living Skin EquivalentsTreating various forms of

wounds with living skin equiva-lents (LSE) has been successful.The two common LSE’s availablein the United States are Apligraf®

(Organogenesis, Canton MA andNovartis Pharmaceuticals, EastHanover NJ) and Dermagraft®

(Advanced BioHealing, La Jolla,CA, USA). These equivalents aredeveloped by tissue-engineeringtechniques.17 These technologi-cally-advanced tissues are madeby culturing human allogeneiccells, such as fibroblasts and ker-atinocytes. While autologous fi-broblasts carry no risk of rejec-tion or infection, more timeis needed to culture thesecells in order to obtain an ad-equate number for healing.Therefore, allogeneic cellswhich are more readily avail-able are used for the LSEgrafts.21

The placement of livingcells on a wound shouldtransform a wound from anarrested chronic state into oneof acute healing.1 The cells arethen placed in different matri-ces, based on the product, toallow for a scaffold for the de-livery of the cells to thewound and also ingrowth ofhost tissues into the graft.The presence of these cells withinthe LSE have shown encouraging

results related to relief of symp-toms, more rapid healing of chron-



Therapies...

Venous ulcerations typicallyare not as limb-threatening as

those caused by pressure, trauma,or complications of diabetes.17 Themedical care for such ulcers, how-ever, is costly as well as the psy-chosocial impact and morbidity forthe patient. These ulcerations canbe very painful and the rate of re-currence is high, as there is usuallyrecurrence within a decade.18

Since the early nineteenth cen-tury, compression bandaging hasbeen the standard of care for theseulcerations. The evolution of thecompression dressings availablehad greatly decreased the time tocomplete healing for these ulcera-tions. High level of compressionwith a multi-layered system isconsidered the most effective withan ulcer healing rate of 60-80% atsix months.19 The level of com-pression achieved with dressingsshould be at least 40 mmHg forvenous ulcerations.18

Today, the care is still evolvingwith the application of graft alter-natives to the ulcerations in con-junction with compression dress-ings. This shows great promise andadvancement in treatment for thesedifficult ulcerations.

A review of the most commonlyreferred to, and current, classifica-tion systems for wounds is impor-tant (Tables 1 and 2).20

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Figure 5: A plantar ulceration present forover six months secondary to diabetic neu-ropathy and Charcot osteoarthropathy. Thisphoto taken after one application ofApligraf.

Figure 6: Same patient after two applications ofApligraf over a two-month period.

TABLE 2

University of Texas Classification for Diabetic Foot Ulcerations

0 I II III

A Pre-ulcerative Superficial Deep ulceration Deep ulcerationlesion, area of ulceration that with exposure with exposurepressure does not include of tendon or of bone or joint

tendon, capsule, capsule, but or bone no bone

B with infection with infection with infection with infection

C with ischemia with ischemia with ischemia with ischemia

D with infection with infection with infection with infectionand ischemia and ischemia and ischemia and ischemia


composed of bovine collagen,which provides a scaffold for the al-logeneic components of the graft.2

Apligraf does not contain the fol-lowing structures typically presentin human skin: blood vessels, hairfollicles, sweat glands, Langerhan’scells, melanocytes, macrophages, orlymphocytes.12

The mechanism of action ofApligraf is not fully understood andcan vary based on the type ofwound; however, mechanisms have

ic and acute wounds, and lessscarring.2

It has been shown that LSE’sprovide for the appropriate re-lease of growth factors and cy-tokines necessary for woundhealing. The adequate amount ofconcentration and combinationof these factors make for an effi-cient and effective wound heal-ing product. Appropriate tissueengineering includes the assur-ance that the product is asepticand will not become contaminat-ed prior to application, and willbe preserved to allow for ade-quate shelf-life.

The advantage of an LSE overcadaver skin is the availabilityand reproducibility of the LSE.LSE’s also do not predispose ahost to infectious disease trans-mission from cadaver skin. BothApligraf and Dermagraft havebeen FDA approved for their usein diabetic foot ulcers and chron-ic non-healing venous ulcerationsThese preparations have under-gone the necessary trials for ap-proval by the FDA for use in theUnited States.12,17 To date, thereare no sufficient data availablecomparing treatment with Apligrafversus Dermagraft. Treatment of ve-nous ulcerations with LSE’s hasshown great promise by healing le-sions more rapidly than with com-pression alone.17

ApligrafApligraf is a living tissue that

interacts both biologically andphysically with a wound. This in-teraction ultimately leads to regen-eration of tissue within the wound.The structure of this skin equiva-lent is unique. It is bi-layered withthe most superficial layer being epi-dermal in nature with allogeneicneonatal foreskin keratinocytesthat form a well-differentiated stra-tum corneum after exposure to anair-liquid interface.2,9,12,22 This mim-ics the architecture of the humanepidermis.

The deeper, dermal layer isformed by cultured, human fibrob-lasts from neonatal foreskin. Thesefibroblasts provide structural pro-teins and also produce additionalmatrix proteins.12 This layer is also

Therapies... been theorized. Thereare currently three pro-posed tiers of Apligraf’smechanism of action. Thefirst is one of graft “take” whichpresumes the graft takes to thewound and is persistent through-out healing.4 There is controversyinvolving the actual persistenceof this graft within the woundand this will be reviewed shortly.It is also theorized to obtain tem-porary wound closure with re-ep-ithelization from the woundmargins.

Lastly, Apligraf has been shownto produce the growth factorsand cytokines that are typicallyproduced by normal healing skinduring the repair process.23 Thesegrowth factors stimulate woundhealing and maintain an extra-cellular matrix necessary for in-growth.4 Evidence has shown theformation of a basement mem-brane and a high degree of revas-cularization within days of theapplication.24

Histologic analysis of ulcera-tions treated with application ofApligraf showed an increasedmucin production, which is theprecursor to fetal wound

healing.25

An immune response of rejec-tion or reaction is of concern withthe use of allogeneic cells and tis-sues. Apligraf has been shown,however, to not illicit an immuno-logical response in the host.12,17,26 Invitro studies have determined thatApligraf does not contain cells thatexpress class II major histocompati-bility complex antigens such asmacrophages, lymphocytes, andLangerhan’s cells.26,27 This is theo-rized to be the reason that no im-mune response occurs.

The persistence of Apligraf in awound and the repercussions ofsuch continue to be a debate. Intheory, Apligraf could function as apermanent skin replacement28

However, in vivo studies involvingits use in chronic wounds suggestthat it does not persist, and actsonly as a temporary graft.22,29 Judg-ment of the presence of Apligraf ina wound clinically is referred to as“clinical persistence.” This is high-ly suggestive in nature when com-pared to more objective DNA stud-


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Figure 7: Dorsal arterial ulceration, one week afterrevascularization.

Figure 8: The same patient after debridement andone application of Apligraf.

Figure 9: The same patient healed aftertwo applications of Apligraf.

The application of Apligrafshould be considered in patientswith chronic, non-healing woundsthat are not responding to stan-dard of care treatments. Once theneed for application has been de-termined by the physician, the bedof the wound should be prepared.This preparation involves debride-ment of any dead or infected tis-sue. Clinical suspicion of an infec-

tion is a con-traindication tothe applicationof Apligraf. Theinfection must betreated and re-solved prior toplacement of thisgraft. Clinicalsuspicion or priordiagnosis of vas-cular insufficien-cy is also consid-ered a contra-in-dication to the

application. However, in patientswho are not able to be revascular-ized and have open wounds, serialapplications of Apligraf haveshown to be beneficial in not onlythe closure of wounds, but also inproviding an additional barrier toinfection (Figures 1-4).

Therefore, that vascular status isnot a true contraindication, butmore a concern in regard to the ef-fectiveness of the graft. This shouldbe strictly considered on an indi-vidual patient basis. Also, with thisgraft, we were reluctant at first touse it on a plantar surface DFU.There was concern that the shearforces occurring here would greatlylimit the effectiveness of the graft.However, with immobilization ofthe area (e.g., CAM walker, walking

cast) weight-bearing has not dimin-ished the effectiveness (Figures 5-6).Apligraf can be considered for mul-tiple applications to a single woundto promote and complete the heal-ing process (Figures 7-9).

An average of 3.9 applicationswas performed in a study evaluat-ing its use in non-healing diabeticfoot ulcerations.12 Complete woundhealing resulted in some woundsafter one or two applications and inothers after subsequent wound ap-plications. The complete woundhealing rate was significantly in-creased in the chronic plantar ul-cerations with Apligraf applicationwhen compared to ulcers treatedsolely with standard of care prac-tices.

The recurrence rate of ulcera-tion, in this study, was lower in thepatients treated with Apligraf. Thisdoes suggest that application ofApligraf produces healed tissue thatis at least as viscoelastically strongas that produced by the normalhealing process, if not a strongertissue. With application on venousulcerations, the recurrence rate wasaround 20% at 12 months. Con-cerning use of Apligraf on venousstasis ulcerations, it has been foundto be particularly advantageous inulcers that have been present for along duration and have a history ofnot responding to standard of carewith compression alone.18

DermagraftDermagraft is a human-derived,

allogeneic dermal fibroblast culture,grown within a biodegradable scaf-fold composed of polyglactin.There is no epidermal componentto this graft. Over the first two



ies. With use in ve-nous ulcerations, clini-

cal persistence has beenfound to be near 40%.17

This study also sug-gested that the clinicalpersistence had no bear-ing on the efficacy ofwound closure; however,when using PCR to deter-mine the persistence ofApligraf based on DNA, itranges between 10-20%,much lower than clinical-ly observed in previous studies.28 Inthis study, a biopsy was taken fromthe Apligraf site and the PCR re-vealed that at four weeks either thekeratinocytes or fibroblasts fromthe neonatal foreskin remained.

Persistence of the DNA from thedermal layer only suggests thatonly the fibroblasts remain at fourweeks. Some suggest that a “silentrejection” of the graft occurs. Thisentails the re-placement of theallogeneic compo-nents with thoseproduced fromthe host. Clinicalremodeling of theApligraf by re-placement of thecomponents withthe host’s cells ap-peared to occur inaround 63% of pa-tients.17 In acutef u l l - t h i c k n e s swounds, it was found that the per-sistence of the Apligraf diminishedover time. It went from 73% at oneweek to 57% at two weeks and 54%at four weeks.30

It also seems that persistence islonger in partial thickness woundswhen compared to full-thicknesswounds. Survival of the graft large-ly is determined by the host re-sponse to the graft, the site, andtype of wound that the graft is uti-lized with. Across the studies, a per-sistence of around four weeks istypically noted.28 The persistence inacute wounds has shown no detec-tion of the graft beyond six weeks.31

In venous ulcers, likely due to theirinflammatory nature, the graft hasbeen shown to not survive pasteight weeks.22

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Figure 11: Completed application of GRAFT-JACKET utilizing staple stabilization.

Figure 10: The application of GRAFTJACKET to anAchilles tendon ulceration.

Fibroblasts in a

chronic wound lose

their ability to

proliferate and form

the matrix, or

scaffold, for repair.

Therapies...


from the wound.3 There is a need toreduce bioburden of a wound toless than 106 bacteria/gram prior tothe application of materials con-taining growth factors or livingskin equivalents.37 The graft is cryo-

preserved, allow-ing for shipmentand storage of upto six monthsprior to use.

The Derma-graft is suppliedin 5 by 7 cm.sheets that mustbe thawed andwashed prior toapplication. Awater bath at atemperature of 37degrees Celsiusshould be used to

emerge the graft within the packagefor several minutes and then itshould be washed with normal ster-ile saline. The graft must be placedon the wound bed and coveredwithin thirty minutes of thawing.The dressing utilized over the Der-magraft varies based on the charac-teristics of the wound. It may con-sist of a moistsaline gauze, hy-drogel, or foamdressing based onthe amount of ex-udate predicted.4) Dermagraft wasFDA approvedbased upon a regi-men of weekly ap-plications (up toeight) until totalwound healingwas achieved.

Dermagraft isFDA-approved foruse on diabeticfoot ulcerationsthat are of greater than six weeksduration and extend through thedermis but without exposed ten-don, joint, muscle, and/or bone.2,4

The use of Dermagraft on venousulcers has previously been studied.An interim analysis reported no sig-nificant difference at week 24, withcomplete healing between the con-trol group and patients treated withone application of Dermagraft.38

However, there was a significant re-duction in the recurrence rate withuse of Dermagraft over the control

weeks of placement, this scaffolddegrades, leaving behind cellularcomponents and proteins.3 Thereare two principle mechanisms ofaction for thisdermal substitute.It facilitates an-giogenesis by pro-viding fibroblaststhat are derivedfrom humann e o n a t a lf o r e s k i n . 1 , 3 2 , 3 3

These derived fi-broblasts depositthe necessary ma-trix proteins forwound healing.The growth fac-tors produced bythis particular graft are fibroblastgrowth factor, hepatocyte growthfactor, insulin-like growth factor,transforming growth factor, andendothelial cell growth factor.1

These are the growth factors need-ed during the phases of woundhealing. Dermagraft also is com-posed of a collagen matrix with ap-propriate receptors and growth fac-tors that allow for the in-growth ofthe host epithelial cells.34

A randomized, controlled,multi-center study evaluating theefficacy of the use of Dermagrafton chronic diabetic foot ulcersfound that in those ulcers ofgreater than six weeks duration,patients experienced a significantclinical benefit when treated withDermagraft compared to treatmentwith conventional therapy alone.1

This is most likely related to theidea that ulcerations of longer du-ration are more deficient in thefactors necessary for wound heal-ing; therefore, Dermagraft providesa more beneficial matrix to thesewounds. The probability that Der-magraft provided a treatment bene-fit was 98.4% in this study. Previ-ous studies have also shown in-creased blood flow to the area ofulceration after Dermagraft place-ment in diabetic patients.35,36

The application of Dermagraftrequires proper wound bed prepara-tion consisting of adequate debride-ment of devitalized tissue, reduc-tion of bioburden, and managingthe amount of exudates elicited

Therapies... group at six months. Ithas yet to achieve FDA ap-proval for venous ulcerations.

IntegraThis graft composite was first

described in 1981 for use on burnvictims to allow for not only theexcision of devitalized tissue butalso the advantage of immediatewound closure.5 Integra (IntegraLifeSciences Corporation, Plains-boro, NJ, USA) artificial skin iscommonly used on burn patients,for purpura fulminans complica-tions, plastic and reconstructivesurgery, as well as chronicwounds.39 This is a biosynthetic,acellular material consisting of adeeper layer of porous, cross-linkedbovine collagen and shark chon-droitin-6-sulfate. This allows forthe regeneration of the dermalcomponent of skin. The upper,more superficial layer of Integra isa silicone sheath that acts as an ar-tificial epidermis that both controlswater content and is a barrier topotential microbial infections.5,39

The critical component to itssuccess is the need for revascular-

ization of the col-lagen, gly-cosaminoglycandermal layer sothat it becomesincorporated intothe wound. Thisrequires thatthere is a secureapposition andstrict immobiliza-tion of the Inte-gra.40 This revas-cularization oc-curs within thefirst 21 days ofplacement. Therevascularization

occurs after ingrowth of vesselsfrom the underlying wound bedand forms a neodermis. After thisincorporation and removal of thesilicone layer, the graft must becovered with an autogenous partialthickness skin graft.5

This second step in the processof closure can only be performed ifthere is good apposition of the graftto the underlying wound and nosigns of infection. Integra is FDA-approved for use in burns and scar


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Treatment of

venous ulcerations

with LSE’s has shown

great promise by

healing lesions more

rapidly than with

compression

alone.

A strong predicting

factor for the

development of an

ulceration is a

patient’s own history

of previous

ulceration.

with a second phase split thicknessskin graft rate of 93%. In a differentstudy, the additional use of fibringlue with the V.A.C. shortened theinterval between placement of Inte-gra and placement of autogenousgraft by 60%.5 The fibrin glue al-lows for further anchorage of theIntegra.

GRAFTJACKETGRAFTJACKET Regenerative Tis-

sue Matrix®

(Wright MedicalTechnology, Ar-lington, TN) is anacellular humandermal bilami-nate matrix. Thisgraft is essentiallya scaffold madeof elastin, colla-gen, proteogly-cans, and bloodvessel channels. Itis derived fromcadaver tissue.42

This graft pro-vides soft tissuecoverage for awound and the

pluripotent membrane allows forrapid revascularization and incor-poration by the host. During theengineering process, the cellularcomponents are removed and thescaffold is transformed into an im-munologically inert graft.

GRAFTJACKET has been docu-mented to be 82-87% effective.42-45

With the exception of one study,the extent of the ulcer did not ex-ceed a Wagner stage 2. Liden, et al.

retrospectively re-viewed the use ofGRAFTJACKET on ul-cerations that pene-trated to tendon, cap-sule, bone, and/orjoint and that may ormay not be ischemicin nature.42 Over halfof the patients in thisstudy population hadan ulcer grade of 3Dby the University ofTexas ulceration classi-fication. This wouldencompass an ulcerthat extended to boneor joint with the pres-ence of ischemia andinfection. The healing

rate in this study was 93.3% withuse of one application of GRAFT-JACKET. The average time to clo-sure for wounds not involving mus-cle, tendon, or bone is seven toeight weeks.43,44,45 The healing timein Liden’s study was comparable atnine weeks.

GRAFTJACKET involves onlyone application (Figures 10-11).There are various thicknesses avail-able (from 0.5 mm. to 2 mm.). Asthe thickness increases for thisgraft, so does its strength. Surgicaltechnique does not vary greatlyfrom previously mentioned grafts;however, there are four main com-ponents to the process that areneeded for success. The first is soak-ing the graft (to achieve rehydra-tion) in sterile saline with a smallamount of the patient’s blood andheparin. This stops the coagulationat the graft’s edge that can occurwith incorporation, allowing im-mediate blood flow.

This rinsing needs to occur forat least 5-10 minutes.42 The woundbed must be prepared by removingall dead and devitalized tissue. Hor-izontal mattress sutures should beused to maximize the contact areaof the graft with the host. Biobur-den remains a concern and shouldbe addressed prior to any applica-tion.

The graft must be placed shinyside down on the wound bed. Thedull side faces outward and resem-bles the basement membrane; thiswill be in contact with the dressing.Prior to placing the moist compres-



Therapies...

revisions.2

Integra is unique because it canbe placed directly upon deep struc-tures, such as tendon, bone, andjoint.41 This makes it a viable op-tion for wounds that remain deepand are considered Wagner gradeIII. This grade of wound typicallyrequires a vascularized flap whichhas the potential for compromisedhealing because of poor blood flowand contamination. Grafting theseareas do present certain challengeswith shear force and poor bloodsupply, however, if overcome, canbe successful in challenging chron-ic wounds with periosteal or ten-don exposure. Other advantages ofthe use of Integra consist of a softerscar due to the formation of a neo-dermis, avoidance of a flap, anddaily dressing changes requiring noanesthesia, which is important inburn victims.39 The major disadvan-tage to the use of Integra is theneed for a second operation that re-quires an autogenous skin graft.

In an effort to increase the ef-fectiveness of Integra and decreasethe length of time for revasculariza-tion of the graft,various methodshave been em-ployed. The use ofnegative pressuretherapy with aV.A.C. (vacuum-assisted closure)system has beenwidely studiedand reported. Thissystem allows forthe removal ofwound fluid, aswell as decreasesperipheral woundedema, improvesblood flow direct-ly into thewound, and decreases bacterial con-tamination.41 This also stabilizes thegraft to the underlying bed, pro-tecting it from shear forces as wellas providing a better means to con-form a dressing to the Integra whenused for deeper wounds. The V.A.C.can be used at pressures of 50-125mmHg.

In a study evaluating negativepressure for Integra, the initial en-graftment rate was a mean of 96%

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Figure 12: GRAFTJACKET one week after application.Non-compliancy led to dehydration of the distal aspectof the graft. Reversed dehydration with application of ahydrogel daily.

Apligraf has been

shown to produce the

growth factors and

cytokines that are

typically produced by

normal healing skin

during the repair

process.


amide bonds and a biocompatibleend product. The manufactureralso uses a method of sterilizationthat eliminates all pathogens onthe matrix.

This graft is FDA-approved foruse on partial to full-thicknesswounds that have moderate toheavy exudate, are pressure, neuro-pathic, venous, surgical, traumatic,or vascular in nature. The advan-tages to this dressing are the

sion dressing, the paper backingto the graft must be removed. Forwounds with a large amount ofexudate, the graft should bemeshed to allow for exudate per-meability. GRAFTJACKET requiresweekly dressing changes startingat five to seven days after place-ment of the graft. If there is alarge amount of exudate, it maybe changed every five to sevendays.

At the time of placement ofthe GRAFTJACKET and for ap-proximately three weeks whilethe basement membrane is dry-ing, mineral oil covered with anon-adhesive dressing should beapplied. After this, antimicrobialfoam wound dressings shouldcontinue every five days until thebasement membrane separates.During the dressing changes, careshould be taken to not disturb thegraft by unnecessary debridement.

Certain techniques can beused in order to “rescue” a graftwith specific dilemmas (Figure12).42

With the development of ahematoma or seroma, the graftshould be punctured to allow forthe draining of fluids. The pres-ence of the fluids in between thegraft and host will lead to failureof the graft to adhere to thewound bed. If there is a lifting ofthe graft off the wound bed with-out evidence of seroma orhematoma, the graft should be re-sutured into place with use of hor-izontal sutures to allow for themaximum amount of surface areacontact.

Unite™

Unite™ biomatrix (Pegasus Bio-logics, Irvine, CA, USA) is a non-reconstituted, type-I collagen ma-trix derived from equine pericar-dial tissue. This is an acellulardressing with organized and cross-linked collagen that is enzyme-re-sistant. This makes the implant re-sistant against any prematuredegradation. Cross-linking of thecollagen is a method of stabilizingthe extracellular matrix of thegraft. Pegasus, the manufacturer,uses their own unique technique ofcross-linking that provides stable

Therapies... strength provided bythe enzyme-resistant col-lagen matrix, the pliabilityof the dressing, and the avail-ability of the graft. This graft isstored at room temperature andhas a shelf-life of two years.

The application process forthe Unite™ biomatrix is similar toother previously-mentioned grafts(Figure 13-15). The wound bedmust be prepared by adequate de-bridement, removing any necroticand infected soft tissue. The graftmust be rinsed prior to the appli-cation in two separate sterile nor-mal saline baths, for approximate-ly two minutes each. After appli-cation of the matrix, it must betrimmed allowing for a 2-4 mm.excess periphery around thewound. It must then be secured tothe wound based on the surgeon’spreference, examples of whichwould be staples or 4-0 nylon su-tures. The dressing must be keptmoist with hydrating ointmentsand a non-adhesive bandage withcompression. Dressings should bechanged at least every three days.If a silver component is used inthe dressing, it should be notedthat the graft may turn black andthis is only a reaction to the silverand not failure of the graft. Thegraft is pre-fenestrated and isavailable in a 3x3 cm. size and9x9 cm. size.

ConclusionHealing a wound requires a

series of cell recruitments, cellproliferation, and protein synthe-sis. Any disruption in the repairprocess can cause an arrest of theprocess leading to a chronic ulcer-ation. This type of ulceration,along with venous stasis ulcera-tions, can be difficult to heal.Technological advancements inscience have allowed for the de-

velopment of a variety of epidermaland dermal substitutes. Under-standing the specifics between thegrafts provides for an easier deci-sion process when determining theappropriate treatment plan forhealing a wound.

Author’s Note: I would like to ex-tend my thanks to Dan Yarmel, athird-year resident at Presbyterian


Continuing

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Figure 14: The same patient after debridement,application and suture stabilization of a Unitegraft, one week.

Figure 15: The same patient three weeks afterthe application of the Unite graft.

Figure 13: Medial malleolus neuropathic pressureulceration of the ankle in a non-controlled type2 diabetic.

Plenum Press, 1996;3-35.11 El-Ghalbzouri A, Gibbs S, Lamme E,

et al. Effects of fibroblasts on epidermal re-generation. Br J Dermatol 2002;147:230-243.

12 Veves AS, Falanga V, Armstrong D,et al. Graftskin, a human skin equivalent,is effective in the management of non-in-fected neuropathic diabetic foot ulcers: aprospective randomized multicenter clini-cal trial. Diabetes Care 2001;24:290-295.

13 Reiber G,Boyko E, Smith D.Lower extremity footulcers and amputa-tions in diabetics.Diabetes in America.2nd ed. Harris MI,Cowie C, Stern M,Eds. NIH publicationNo. 95, 1995, 1468.

14 Nolan C,Beaty J, Bagdade J.Further characteriza-tion of the impairedbactericidal functionof granulocytes inpatients with poorlycontrolled diabetes.D i a b e t e s1978;27:889-894.

15 Veves A, Ak-bari C, Primavera J,Donaghue V, et al.Endothelial dysfunc-tion and the expres-sion of endothelialnitric oxide syn-

thetase in diabetic neuropathy, vasculardisease, and foot ulceration. Diabetes1998;47:457-463.

16 Lavery L, Armstrong D, Vela S, etal. Practical criteria for screening patientsat high risk for dia-betic foot. Arch In-tern Med 1998;158:157-162.

17 Falanga V,Margolis D, AlverezO, Auletta M, et al.Rapid healing of ve-nous ulcers and lackof clinical rejectionwith allogeneic cul-tured human skinequivalent. Arch Der-matol 1998;134:293-300.

18 O’Donnell T,Lau J. A systemic re-view of randomizedcontrolled trials of wound dressings forchronic venous ulcer. J Vasc Surg2006;44:1118-1125.

19 Cullum N, Nelson E, Fletcher A,Sheldon T. Compression bandages andstockings for venous leg ulcers. CochraneLibrary 1999;4:1-19.

20 Wagner F. The diabetic foot. Ortho-

pedics 1987;10:163.21 Bello Y, Falabella A, Eaglstein W.

Tissue-engineered skin. Current status inwound healing. Am J Clin Dermatol2001;2:305-313.

22 Phillips J, Manzoor J, Rojas A, et al.The longevity of a bilayered skin substi-tute after application to venous ulcers.Arch Dermatol 2002;138:1079-1081.

23 Eaglstein W, Iriondo M, Laszio K. Acomposite skin substitute (Graftskin) forsurgical wounds: a clinical experience.Dermatol Surg 1995;21:839-843.

24 Hansbrough J, Morgan J, GreenleafG, et al. Evaluation of Graftskin compos-ite grafts on full-thickness wounds onathymic mice. J Burn Rehabil1994;15:346-353.

25 Badiavas E, Paquette D, Carson P,Falanga V. Human chronic wounds treat-ed with bioengineered skin: histologic evi-dence of host-graft interactions. J AmAcad Dermatol 2002;46:524.

26 Theobold V, Lauer J, Kaplan F, et al.‘Neutral allografts:’ lack of allogeneic stim-ulation by cultured human cells express-ing MHC class I and class II antigens.Transplantation 1993;55:128-133.

27 Wilkins L, Watson S, Prosky S, et al.Development of a bilayered living skinconstruct for clinical applications.Biotechnol Bioeng 1994;43:747-756.

28 Hu S, Kirsner R, Falanga V, et al.Evaluation of Apligraf persistence andbasement membrane restoration in donorsite wounds: a pilot study. Wound RepReg 2006;14:427-433.

29 Fivenson D, Scherschum L, Chou-cair M, et al. Graftskin therapy in epider-molysis bullosa. J Am Acad Dermatol2003;48:886-892.

30 Eaglstein W, Alvarez O, Auletta M,et al. Acute excisional wounds treated

with a tissue-engi-neered skin(Apligraf). DermatolSurg 1999;25:195-201.

31 Griffeiths M,Ojeh J, LivingstoneR, et al. Survival ofthe Apligraf in acutehuman wounds.Tissue Eng 2004;10:1180-1195.

32 Pinney E, LiuK, Sheeman B, Mans-bridge J. Humanthree-dimensional fi-brblasts cultures ex-press angiogenic ac-

tivity. J Cell Physiol 2000;183:74-82.33 Harding K, Brassard A, Dolynchuck K.

Treatment of “hard to heal” venous leg ulcerswith a human dermal replacement tissue(Dermagraft): a clinical, laboratory evaluation(Abstract). First World Wound HealingCongress, Melbourne, Australia, 2000.



Therapies...

Hospital Foot and Ankle SurgicalResidency for his assistance in the

preparation of this article.

References1 Marston W, Hanft J, Norwood P,

Pollak R. The efficacy and safety of Der-magraft in improvingthe healing of chron-ic diabetic foot ulcers:results of a prospec-tive randomized trial.Diabetes Care2003;26:1701-1705.

2 Wong T, Mc-Grath J, Navsaria H.The role of fibroblastsin tissue engineeringand regeneration. BJour Derm2007;156:1149-1155.

3 Marston W.Dermagraft®, a bio-engineered humandermal equivalent forthe treatment ofchronic non-healingdiabetic foot ulcer.Expert Rev MedicalDevices 2004;1:21-31.

4 Ehrenreich M,Ruszczak Z. Updateon tissue-engineeredbiological dressings.Tissue Engineering2006;12:2407-2423.

5 Jeschke M, Rose C, Angele P, et al.Development of new reconstructive tech-niques: use of Integra in combinationwith fibrin glue and negative-pressuretherapy for reconstruction of acute andchronic wounds. Plast Recontr Surg2004;113:525.

6 Falanga V, Grinnel B, Gilchrist Y, etal. Experimental approaches to chronicwounds. Wound Rep Regen 1995;3:132-140.

7 Hehenberger K, Heilborn K, BrismarK, Hansson A. Inhibited proliferation of fi-broblasts derived from chronic diabeticwounds and normal dermal fibroblaststreated with high glucose is associatedwith increased formation of L-lactate.Wound Rep Regen 1998;6:135-141.

8 Adams S, Sabesan V, Easley M.Wound healing agents. Foot Ankle Clin NAmer 2006;11:745-751.

9 Milstone L, Asgari M, Schwartz P,Hardin-Young J. Growth factor expres-sion, healing, and structural characteris-tics of Graftskin (Apligraf®). Wounds2000;12 (5 Suppl A):12A-19A.

10 Clark R. Wound repair: overviewand general considerations. In: TheMolecular and Cellular Biology of WoundRepair (Clark R, ed). New York, NY:

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The application of

Dermagraft requires

proper wound bed

preparation consisting

of adequate

debridement of

devitalized tissue,

reduction of

bioburden, and

managing the amount

of exudates elicited

from the wound.

Integra is

unique because

it can be placed

directly upon deep

structures,

such as tendon,

bone, and joint.


Continuing

Medical Education34 Krejci-Papa N, Hoang A, Hansbrough J. Fibroblast sheets en-

able epithelization of wounds that do not support keratinocyte mi-gration. Tissue Engin 1999;5:555-561.

35 Newton D, KhanF, Belch J, et al. Bloodflow changes in diabet-ic foot ulcers treatedwith dermal replace-ment therapy. J FootAnkle Surg 2002;41:233.

36 Omar A, MavorA, Jones A, et al. Treat-ment of venous leg ul-cers with Dermagraft.Eur J Vasc EndovascSurg 2004;27:666.

37 Browne A, Vearn-combe M, Sibbald R.

High bacterial load in asymptomatic diabetic patients withneruotrophic ulcers retards wound healing after application of Der-magraft. Ostomy Wound Management 2001;10:44-49.

38 Advanced Tissue Sciences Inc. 1996. Form 10K.39 Violas P, Abid A, Darodes P, et al. Integra artificial skin in the

management of severe tissue defects, including bone exposure, ininjured children. J Ped Orthoped B 2005;14:381-384.

40 McEwan W, Brown T, Mills S, Muller M. Suction dressings tosecure a dermal substitute. Burns 2004;30: 259-261.

41 Molnar J, De-Franzo A, Hadaegh A, etal. Acceleration of Inte-gra incorporation incomplex tissue defectswith subatmosphericpressure. Plast ReconstrSurg 2004;113:1339-1346.

42 Liden BA, Hart-man JF, Wright ML.Single application of ahuman acellular dermalregenerative tissue ma-trix for the manage-ment of complex lowerextremity wounds: sur-gical technique and preliminary results. Provided by Wright MedicalResearch Facility.

43 Brigido SA, Boc SF, Lopez RC. Accelerated healing of lower ex-tremity wounds with GRAFTJACKET: a human acellular regenerativetissue matrix. Orthopedics2004;27:145-149.

44 Martin BR, San-galang M, Wu SC, Arm-strong DG. Outcomes ofallogeneic matrix therapyin treatment of diabeticfoot wounds. Internation-al Wound Journal2005;2(2):161-165.

45 Yeager DA, Oliverio J.Investigation of GRAFT-JACKET regenerative tissuematrix for ulcer repair onfull-thickness lower extremi-ty ulcers. Accepted as anACFAS 2006 Scientific PosterExhibit.

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1) What are the living skin equivalent graftsavailable for ulceration coverage?

A) GraftjacketB) ApligrafC) DermagraftD) Both B and C

2) What constitutes a living skin equivalent forit to be labeled as such?

A) The culturing of human allogeneic cellsfor transfer to a host’s wound siteB) The use of autologous cells for transferto a wound siteC) Both A and BD) None of the above

3) What is lacking in the environment of achronic ulceration?

A) Proper migration of the keratinocytesB) The ability of fibroblasts to proliferateC) Growth factors necessary for the heal-ing processD) All of the above

4) What is a principle that should be remem-bered when considering the application of adermal/epidermal graft?

A) Presence of infection should not deterfrom the application of a graftB) All grafts discussed in this article can beused to cover tendon, muscle, and/or boneC) If able and needed, revascularizationshould be performed prior to the applica-tion of any graftD) Both A and B

5) Prior to the application of all the graftsmentioned here, what must be done?

A) The wound bed should be adequatelydebrided using standard practices prior tothe application of the graftB) Proper stabilization of the graft to hostis not necessaryC) Multiple application of all grafts dis-cussed is often needed to complete closureD) Both B and C

6) Which graft is composed of a non-reconsti-tuted, type I collagen matrix derived from

See instructions and answer sheet on pages 252-254.


E X A M I N A T I O N

Dr. Rab-john is anassociateat the Ar-l i n g t o n /MansfieldFoot &A n k l eCenters inTexas. Shecompletedthe Graduate Hospital Foot andAnkle Surgical Program inPhiladelphia, PA and graduatedfrom Des Moines University/Col-lege of Podiatric Medicine andSurgery.

Unite™ biomatrix

is stored at room

temperature and

has a shelf-life

of two years.

GRAFTJACKET

involves only one

application.

12) Why is it believed that LSE donot cause an immune response ofrejection?

A) The graft is not consideredallogeneicB) The graft does not containcells that express class II majorhistocompatibility complexantigensC) It is composed of autoge-nous cellsD) Both A and B

13) Which of the following bestdescribes the phenomenon of“silent rejection?”

A) The replacement of the allo-geneic components with thoseproduced from the hostB) The transfer of purely auto-genic cells to the wound bedvia a graftC) The host’s immune responseto the transplanted graft andsubsequent rejectionD) All of the above

14) Which graft requires a two-step procedure, the second beinga autogenous skin graft?

A) ApligrafB) DermagraftC) IntegraD) GRAFTJACKET

15) Which graft has been success-ful in clinical trials for coveringwounds extending to the muscle,tendon, and/or bone?

A) UniteB) DermagraftC) ApligrafD) Integra

16) Which of the following occursas a result of using a V.A.C. (vacu-um-assisted closure) over a graft?

A) Removal of wound fluidB) Decreases peripheral edemaC) Improves blood flow to thewoundD) All of the above

equine pericardial tissue?A) GraftjacketB) ApligrafC) UniteD) Integra

7) Which graft is composed oftwo layers, one consisting of allo-geneic neonatal foreskin ker-atinocytes and the other layer ofhuman cultured fibroblasts?

A) DermagraftB) ApligrafC) UniteD) GRAFTJACKET

8) Which graft is composed ofporous, cross-linked bovine colla-gen and shark chondroitin-6-sul-fate?

A) UniteB) GRAFTJACKETC) IntegraD) Apligraf

9) Which graft is composed ofhuman-derived, allogeneic der-mal fibroblasts within abiodegradable scaffold composedof polyglactin?

A) GRAFTJACKETB) UniteC) IntegraD) Dermagraft

10) Which graft is composed oftissue from a cadaver and is anacellular human dermal bilami-nate matrix?

A) ApligrafB) DermagraftC) GRAFTJACKETD) Unite

11) Which of the following struc-tures is not found in Apligraf,comprising the theory of why thisgraft is so immunologically inert?

A) KeratinocytesB) MacrophagesC) LymphocytesD) Both B and C

E X A M I N A T I O N


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SEE INSTRUCTIONSAND ANSWER SHEETON PAGES 252-254

17) At what pressure should theV.A.C. system be used for clo-sure of a peripheral wound?

A) 25-50 mmHgB) 50-125 mmHgC) 125-175mmHgD) >200 mmHg

18) Using the Wagner classifica-tion system for DFU, whichgrade describes a wound withdepth involving bone?

A) 1B) 2C) 3D) 4

19) Using the University of Texasclassification for DFU, a wounddescribed as IIIB would havewhich of the following charac-terisitics?

A) Superficial ulceration notinvolving tendon that alsohas an infection presentB) Superficial ulceration in-volving tendon that is also is-chemicC) Deep ulceration with ex-posure of bone that involvesinfection and ischemiaD) Deep ulceration with ex-posure of bone that involvesinfection, but no ischemia

20) Which of the followinggrafts has been found to have astrong immunologic response inclinical studies?

A) IntegraB) GRAFTJACKETC) ApligrafD) None of the above

the use of objectives epidermal/dermal cme1.pdfallows for a break in the continuity and integrity of...

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