1、Designation: F 2311 06Standard Guide forClassification of Therapeutic Skin Substitutes1This standard is issued under the fixed designation F 2311; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide defines terminology and provides a system ofclassification for products that can be substituted for human oranimal skin grafts (or
3、 grafts of the dermal or epidermalcomponent tissues of skin) in medical and surgical therapies.This guide is intended to include (or be expandable to) possiblefuture tissue engineered skin technology that could providenovel or superior therapeutic properties to those of natural skingrafts.1.2 As muc
4、h as possible, terminology is based on medicaldictionary definitions.1.3 Substitutes for skin grafts are classified by clinicalutility only; the classification is independent of the technologyused to make a skin substitute, its components, or whether thesources of components include human or animal
5、tissue or otherbiological or non-biological materials.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility
6、of regulatory requirements prior to use.2. Terminology2.1 Definitions:2.1.1 skin, nthe outer integument or covering of the body,consisting of the dermis and the epidermis, and resting uponthe subcutaneous tissues. Dorlands2.1.2 tissue, nan aggregation of similarly specialized cellsunited in the perf
7、ormance of a particular function.Dorlands22.1.3 Skin Lesions:2.1.3.1 full-thickness skin wound, na skin wound with theloss of epidermis, and all of the dermis or at least the depth ofdermis that includes most or all sources of epidermal cells fromepidermal adnexae (glands and follicles).2.1.3.2 lesi
8、on, nany pathological or traumatic discontinu-ity of tissue or loss of function of a part. In this guide, “skinlesion” is intended to encompass skin wounds and skin ulcers.Dorlands2.1.3.3 open wound, na wound that communicates withthe atmosphere by direct exposure. Dorlands2.1.3.4 partial thickness
9、skin wound, na skin wound withthe loss of the epidermis and part of the dermis, but retaininga layer of viable dermal tissue that includes the sources ofepidermal cells from which the wound can heal spontaneouslyby epidermal tissue regeneration.2.1.3.5 ulcer, na local defect, or excavation of the su
10、rfaceof an organ or tissue, which is produced by the sloughing ofinflammatory necrotic tissue. Dorlands2.1.3.6 wound, nan injury or damage, usually restricted tothose caused by physical means with disruption of the normalcontinuity of structures. Called also injury and trauma.Dorlands2.1.4 Skin Woun
11、d Physiology:2.1.4.1 granulations, ngranulation tissue.2.1.4.2 granulation tissue, nthe newly formed vasculartissue normally produced in the healing of wounds of softtissue and ultimately forming the cicatrix scar; it consists ofsmall, translucent, red, nodular masses or granulations thathave a velv
12、ety appearance. Dorlands2.1.4.3 scar, nfibrous tissue replacing normal tissues de-stroyed by injury or disease. Stedmans32.1.4.4 wound contraction, nthe shrinkage and spontane-ous closure of open skin wounds. Dorlands2.1.4.5 wound contracture, na condition of fixed highresistance to passive stretch
13、of muscle, skin or joints resultingfrom fibrosis and scarring of the skin or the tissues supportingthe muscles or the joints, or both. (This definition is amodification of Dorlands definition of contracture, “a condi-tion of fixed high resistance to passive stretch of muscle,resulting from fibrosis
14、of the tissues supporting the muscles orthe joints, or disorders of the muscle fibers,” because thatdefinition does not address fibrosis and scarring in skin.)2.1.4.6 wound inflammation, na localized protective re-sponse elicited by injury or destruction of tissues, which servesto destroy, dilute, o
15、r wall off (sequester) both the injuriousagent and the injured tissue. It is characterized in the acuteform by the classical signs of pain (dolor), heat (calor) redness1This guide is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Devices and Materials and is the direct responsib
16、ility of SubcommitteeF04.41 on Classification and Terminology for TEMPs.Current edition approved May 1, 2006. Published May 2006. Originallyapproved in 2003. Last previous edition approved in 2003 as F 2311 032Dorland, WAN, Dorlands Illustrated Medical Dictionary, 29th Ed., W. B.Saunders Company, Ph
17、iladelphia, 2000.3Stedman, T. L., Stedmans Medical Dictionary, 27th Ed., Lippincott Williamsexudation of fluids, includingplasma proteins; and leukocytic migration into the inflamma-tory focus. Dorlands2.1.5 Skin Wound Closure and Healing:2.1.5.1 heal, vto restore wounded parts or to makehealthy. Do
18、rlands2.1.5.2 healing, nthe restoration of integrity to injuredtissue. Dorlands2.1.5.3 DiscussionIn the surgical wound closure, an im-portant distinction is made according to whether the surgeonexpects the healing to be accomplished by granulation tissue.This distinction is made because in the norma
19、l physiology ofwound healing, granulation tissue matures into scar withwound contracture, which is an undesirable outcome (see4.1.2). Wound closure “by approximating the wound edges orperforming a skin autograft” is called “healing by first inten-tion,” and wound closure by “allowing spontaneous hea
20、lingfrom the edges” is called “healing by second intention.”healing by first intention, nhealing in which union orrestoration of continuity occurs directly without intervention ofgranulations. Dorlandshealing by second intention, nunion by closure of a woundwith granulations which form from the base
21、 and both sidestoward the surface of the wound. Dorlands2.1.5.4 tissue regeneration, nhealing in which lost tissueis replaced by proliferation of cells, which reconstruct thenormal architecture. medweb42.1.5.5 tissue repair, nhealing in which lost tissue isreplaced by a fibrous scar, which is produc
22、ed from granulationtissue. medweb2.1.5.6 wound closure, nthe provision of an epithelialcover over a wound. It can be accomplished by approximatingwound edges, performing a skin autograft, or allowingspontaneous healing from the edges. Churchills52.1.6 Therapies for Skin Wounds and Ulcers:2.1.6.1 mai
23、ntenance therapy, ntherapy of chronically illpatients that is aimed at keeping the pathology at its presentlevel and preventing exacerbation.2.1.6.2 skin allograft therapy, nthe treatment of skinwound or skin ulcer by the temporary topical application ofskin allograft(s).2.1.6.3 skin replacement sur
24、gery, nsurgery that perma-nently replaces lost skin with healthy skin.2.1.7 Biomaterials and Grafts:2.1.7.1 allograft, na graft of tissue between individuals ofthe same species but of disparate genotype. Called alsoallogeneic graft and homograft. Dorlands2.1.7.2 autograft, na graft of tissue derived
25、 from anothersite in or on the body of the organism receiving it.Dorlands2.1.7.3 biomaterial, nany substance (other than a drug),synthetic or natural, that can be used as a system or part of asystem that treats, augments, or replaces any tissue, organ, orfunction of the body. Dorlands2.1.7.4 dermal
26、autograft, na skin autograft from whichepidermis and subcutaneous fat have been removed; usedinstead of fascia6in various plastic surgery procedures.Dorlands2.1.7.5 dressing, nany of various materials utilized forcovering and protecting a wound. Dorlands2.1.7.6 engraftment, nincorporation of grafted
27、 tissue intothe body of the host. Dorlands2.1.7.7 epidermal autograft, nan autograft consisting pri-marily of epidermal tissue, including keratinocyte stem cells,but with little dermal tissue.72.1.7.8 full thickness skin autograft, na skin autograftconsisting of the epidermis and the full thickness
28、of the dermis.Dorlands2.1.7.9 graft, nany tissue or organ for implantation ortransplantation. Dorlands2.1.7.10 graft take, nengraftment.2.1.7.11 skin substitute, na biomaterial, engineered tissue,or combination of biomaterials and cells or tissues that can besubstituted for a skin allograft, a skin
29、autograft, an epidermalautograft, or a dermal autograft in a clinical procedure.2.1.7.12 split thickness skin autograft, na skin autograftconsisting of the epidermis and a portion of dermis.Dorlands2.1.7.13 xenograft, na graft of tissue transplanted be-tween animals of different species. Called also
30、 heterograft,heterologous graft and heteroplastic graft.8Dorlands2.1.7.14 xenotransplantation, nany procedure that in-volves the transplantation, implantation, or infusion into ahuman recipient of either (a) live cells, tissues, or organs froma nonhuman animal source, or (b) human body fluids, cells
31、,tissues or organs that have had ex vivo contact with livenonhuman animal cells, tissues or organs.94Hiley, P., and Barber, P. C., General Pathology (Pathology FoundationCourse), Chapter 3, Healing and Repair, Department of Pathology, University ofBirmingham, U.K., http:/medweb.bham.ac.uk/http/depts
32、/path/Teaching/foundat/repair/healing.html.5Churchills Illustrated Medical Dictionary, Churchill Livingstone, New York,1989.6“a sheet or band of fibrous tissue such as lies deep to the skin ” (Dorlands).7For practical details, see Fang, P., Engrav, L. H., Gibran, N. S., Horani, S.,Kiriluk, D. B., Co
33、le, J. K., Fleckman, P., Heimbach, D. M., Gauer, G. J., Matsumura,H., Warner, P., “Dermatome steeing for autografts to cover Integrat,” J Burn CareRehabil, 23, 2002, pp. 327-332; and Kagan, R. J., Invited editorial J Burn CareRehibil, 23, 2002, pp. 326.8Note that the United States Public Health Serv
34、ice (USPHS) and the UnitedStates Food and Drug Administration define “Xenotransplantation” more broadly as“any procedure that involves the transplantation, implantation, or infusion into ahuman recipient of either (a) live cells, tissues, or organs from a nonhuman animalsource, or (b) human body flu
35、ids, cells, tissues, or organs that have had ex vivocontact with live nonhuman animal cells, tissues or organs.” Because this guide isintended to classify skin substitutes by clinical equivalency, and not by composition,the dictionary definition is used, for this guide only. It should be understood
36、that anallograft or autograft substitute may include animal components which cause it to bealso a xenotransplant by the Food and Drug Administration definition.9Guidance for Industry, Source Animal, Product, Preclinical, and Clinical IssuesConcerning the Use of Xenotransplantation Products in Humans
37、, U.S. Departmentof Health and Human Services, Food and DrugAdministration, Center for BiologicsEvaluation and Research (CBER), April 2003.F23110622.1.7.15 xenotransplantation products, nxeno-transplantation products include live cells, tissues or organsused in xenotransplantation.92.1.7.16 Discussi
38、onXenografts and xenotransplantationproducts comprise overlapping but not congruent groups ofskin substitutes. Autograft, allograft, and xenograft are tradi-tional terms to describe tissue used in surgical procedures.Because autograft involves the harvesting of the patients owntissue, care is taken
39、to preserve its viability. However, allograftand xenograft are not necessarily alive and may have beenfrozen for storage. Skin substitutes may combine attributes ofautograft, allograft, xenograft, and xenotransplantation prod-ucts, depending on the origin of cells or tissues used in theirmanufacture
40、, and whether these components are alive or not.For example, a substitute for epidermal autograft composed ofcultured autologous epidermal cells grown on a feeder layer oflive non-human cells is a xenotransplantation product as wellas an autograft substitute.3. Significance and Use3.1 This guide is
41、intended to provide the foundation ofstandards for clinical assessment, clinical performance, andpreclinical assessment of substitutes for skin grafts.3.2 This guide is intended to aid accurate claims andlabeling for the clinical utilities of substitutes for skin grafts inregulatory reviews.3.3 In t
42、his guide, “replacement” and “substitute” havedifferent meanings, although they can be used synonymouslyin ordinary English. “Replacement” is used only as an adjec-tive in the context of “skin replacement surgery,” which isdefined in 2.1.6.3. “Substitute” is used only as a noun in thecontext of “ski
43、n substitute,” which is defined in 2.1.7.11.4. Normal Physiology of Skin Wound Healing4.1 Normal Physiology of Healing by Second Intention ofFull Thickness Skin Wounds:4.1.1 The immediate physiological response to a full thick-ness open skin wound includes wound inflammation, edema,and fluid loss. F
44、or wounds of large area, there may also be asystemic physiological response characterized by fever, hyper-catabolic metabolism, and an increased vulnerability to infec-tion. Such a wound is life threatening.4.1.2 Following the immediate physiological response, tis-sue repair replaces lost dermal tis
45、sue by a fibrous scar that isproduced from granulation tissue.4.1.3 If the wound is contracted enough by the dermal tissuerepair process, the wound is closed by regenerated epidermiscreated by migration and proliferation of epidermal tissue fromthe wound margins.4.1.4 Systemic physiology during heal
46、ing by second inten-tion: A full or partial thickness open skin wound that is toolarge in surface area to be promptly closed by wound contrac-tion and epidermal migration from the margin may be accom-panied by continued life threatening systemic physiologicalresponses.4.1.5 In addition to the partia
47、l or complete immobilizationof joints, wound contracture and the formation of scar tissuecan result in chronic fragility of the overlaying epidermaltissue, discomfort, and unacceptable cosmetic appearance.4.2 Skin Replacement Surgery:4.2.1 Definitions:4.2.1.1 clean surgical skin wound, na full or pa
48、rtialthickness skin wound that is created by surgical excision orincision and that is free of necrotic tissue, without significantbleeding, and without significant microbial contamination. Forexample, see ICD-9-CM procedure code 86.2210for surgicalexcision.4.2.1.2 dermal tissue engraftment, nengraft
49、ment of der-mal tissue resulting in reestablishment of vascular connectionswith cellular and extracellular matrix remodeling in the dermis.4.2.1.3 epidermal tissue engraftment, nengraftment of anepidermal autograft by a process of epidermal tissue regenera-tion resulting in a confluent epidermis and permanent woundclosure. (Epidermal appendages such as hair are not regener-ated.)4.2.1.4 wound closure immediate physiological response,nan immediate restoration of some of the physiologicalfunctions of s
