Research Papers

Development of the Mechanical Properties of Engineered Skin Substitutes After Grafting to Full-Thickness Wounds

[+] Author and Article Information
Edward A. Sander

Department of Biomedical Engineering,
University of Iowa,
Iowa City, IA 52242;
Department of Surgery,
University of Cincinnati College of Medicine,
Cincinnati, OH 45267;
Research Department
Shriners Hospital for Children, Cincinnati,
Cincinnati, OH 45267
e-mail: edward-sander@uiowa.edu

Kaari A. Lynch

Department of Surgery
University of Cincinnati College of Medicine
Cincinnati, OH 45267;
Research Department
Shriners Hospital for Children, Cincinnati,
Cincinnati, OH 45267

Steven T. Boyce

Department of Surgery,
University of Cincinnati College of Medicine
Cincinnati, OH 45267;
Research Department
Shriners Hospital for Children, Cincinnati,
Cincinnati, OH 45267

1Corresponding author.

Contributed by the Bioengineering Division of ASME for publication in the Journal of Biomechanical Engineering. Manuscript received October 15, 2013; final manuscript received December 12, 2013; accepted manuscript posted April 10, 2014; published online April 10, 2014. Assoc. Editor: David Corr.

J Biomech Eng 136(5), 051008 (Apr 10, 2014) (7 pages) Paper No: BIO-13-1489; doi: 10.1115/1.4026290 History: Received October 15, 2013; Revised December 12, 2013; Accepted April 10, 2014

Engineered skin substitutes (ESSs) have been reported to close full-thickness burn wounds but are subject to loss from mechanical shear due to their deficiencies in tensile strength and elasticity. Hypothetically, if the mechanical properties of ESS matched those of native skin, losses due to shear or fracture could be reduced. To consider modifications of the composition of ESS to improve homology with native skin, biomechanical analyses of the current composition of ESS were performed. ESSs consist of a degradable biopolymer scaffold of type I collagen and chondroitin-sulfate (CGS) that is populated sequentially with cultured human dermal fibroblasts (hF) and epidermal keratinocytes (hK). In the current study, the hydrated biopolymer scaffold (CGS), the scaffold populated with hF dermal skin substitute (DSS), or the complete ESS were evaluated mechanically for linear stiffness (N/mm), ultimate tensile load at failure (N), maximum extension at failure (mm), and energy absorbed up to the point of failure (N-mm). These biomechanical end points were also used to evaluate ESS at six weeks after grafting to full-thickness skin wounds in athymic mice and compared to murine autograft or excised murine skin. The data showed statistically significant differences (p <0.05) between ESS in vitro and after grafting for all four structural properties. Grafted ESS differed statistically from murine autograft with respect to maximum extension at failure, and from intact murine skin with respect to linear stiffness and maximum extension. These results demonstrate rapid changes in mechanical properties of ESS after grafting that are comparable to murine autograft. These values provide instruction for improvement of the biomechanical properties of ESS in vitro that may reduce clinical morbidity from graft loss.

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Supp, D. M., and Boyce, S. T., 2005, “Engineered Skin Substitutes: Practices and Potentials,” Clin. Dermatol., 23(4), pp. 403–412. [CrossRef] [PubMed]
Boyce, S. T., 2004, “Fabrication, Quality Assurance, and Assessment of Cultured Skin Substitutes for Treatment of Skin Wounds,” Biochem. Eng. J., 20(2), pp. 107–112, 2004. [CrossRef]
American Burn Association, 2013 National Burn Repository, American Burn Association, Chicago, IL.
MacNeil, S., 2007, “Progress and Opportunities for Tissue-Engineered Skin,” Nature, 445(7130), pp. 874–880, 2007. [CrossRef] [PubMed]
Zeng, Q., Macri, L. K., Prasad, A., Clark, R. A. F., Zeugolis, D. I., Hanley, C., Garcia, Y., and Pandit, A., 2011, “Skin Tissue Engineering”, Comprehensive Biomaterials, P.Ducheyne, K.Healy, D. E.Hutmacher, D. W.Grainger, and C. J.Kirkpatrick, eds., Elsevier, Philadelphia, PA, pp. 467–499.
Boyce, S. T., Kagan, R. J., Greenhalgh, D. G., Warner, P., Yakuboff, K. P., Palmieri, T., and Warden, G. D., 2006, “Cultured Skin Substitutes Reduce Requirements for Harvesting of Skin Autograft for Closure of Excised Full-Thickness Burns,” J. Trauma, 60(4), pp. 821–829. [CrossRef] [PubMed]
Brusselaers, N., Pirayesh, A., Hoeksema, H., Richters, C. D., Verbelen, J., Beele, H., Stijn, I. B., and Monstrey, S., 2010, “Skin Replacement in Burn Wounds,” J. Trauma, 68(2), pp.490–501. [CrossRef] [PubMed]
Powell, H. M., McFarland, K. L., Butler, D. L., Supp, D. M., and Boyce, S. T., 2009, “Uniaxial Strain Regulates Morphogenesis, Gene Expression, and Tissue Strength in Engineered Skin, Tissue Eng. A., 16(3), pp. 1083–1092. [CrossRef]
Boyce, S. T., Supp, A. P., Wickett, R. R., Hoath, S. B., and Warden, G. D., 2000, “Assessment With the Dermal Torque Meter of Skin Pliability After Treatment of Burns With Cultured Skin Substitutes,” J. Burn Care Res., 21(1), pp. 55–63. [CrossRef]
Grenier, G., Remy-Zolghadri, M., Larouche, D., Gauvin, R., Baker, K., Bergeron, F., Dupuis, D., Langelier, E., Rancourt, D., Auger, F. A., and Germain, L., 2005, “Tissue Reorganization in Response to Mechanical Load Increases Functionality,” TIssue Eng., 11(1–2), pp.90–100. [CrossRef] [PubMed]
Boyce, S. T., Kagan, R. J., Yakuboff, K. P., Meyer, N. A., Rieman, M. T., Greenhalgh, D. G., and Warden, G. D., “Cultured Skin Substitutes Reduce Donor Skin Harvesting for Closure of Excised, Full Thickness Burns,” Ann. Surg., 235(2), pp. 269–279. [CrossRef] [PubMed]
Boyce, S. T., Kagan, R. J., Meyer, N. A., Yakuboff, K. P., and Warden, G. D., 1999, “The 1999 Clinical Research Award. Cultured Skin Substitutes Combined With Integra Artificial Skin to Replace native Skin Autograft and Allograft for the Closure of Excised Full-Thickness Burns,” J. Burn Care Rehabil., 20(6), pp. 453–461. [CrossRef] [PubMed]
Swope, V. B., Supp, A. P., and Boyce, S. T., 2002, “Regulation of Cutaneous Pigmentation by Titration of Human Melanocytes in Cultured Skin Substitutes Grafted to Athymic Mice,” Wound Rep. Regen., 10(6), pp. 378–386. [CrossRef]
Boyce, S. T., Supp, A. P., Swope, V. B., Warden, G. D., 2002, Vitamin C Regulates Keratinocyte Viability, Epidermal Barrier, and Basement Membrane In Vitro, and Reduces Wound Contraction After Grafting of Cultured Skin Substitutes,” J. Invest. Dermatol., 118(4), pp. 565–572. [CrossRef] [PubMed]
Boyce, S. T., 1999, “Methods for the Serum-Free Culture of Keratinocytes and Transplantation of Collagen-GAG-Based Skin Substitutes,” Tissue Engineering Methods and Protocols Totowa, J.Morgan and M.Yarmush, eds., Humana Press Inc., New Jersey, pp. 365–389.
Boyce, S. T., and Ham, R. G., 1983, “Calcium-Regulated Differentiation of Normal Human Epidermal Keratinocytes in Chemically Defined Clonal Culture and Serum-Free Serial Culture,” J. Invest. Dermatol., 81, pp. 33s–40s. [CrossRef] [PubMed]
Shipley, G. D., and Pittelkow, M. R., 1987, “Control of Growth and Differentiation In Vitro of Human Keratinocytes Cultured in Serum-Free Medium,” Arch. Dermatol., 123(11), pp. 1541a–1544a. [CrossRef] [PubMed]
Boyce, S. T., Christianson, D. J., Hansbrough, J. F., 1988, “Structure of a Collagen-GAG Dermal Skin Substitute Optimized for Cultured Human Epidermal Keratinocytes,” J. Biomed. Mater. Res., 22(10), pp. 939–957. [CrossRef] [PubMed]
Boyce, S. T., Foreman, T. J., English, K. B., Stayner, N., Cooper, M. L., Sakabu, S., and Hansbrough, J. F., 1991, “Skin Wound Closure in Athymic Mice with Cultured Human Cells, Biopolymers, and Growth Factors,” Surgery, 110(5), pp. 866–876. [PubMed]
Quinn, K. P., and Winkelstein, B. A., 2007, “Cervical Facet Capsular Ligament Yield Defines the Threshold for Injury and Persistent Joint-Mediated Neck Pain,” J. Biomech., 40(10), pp. 2299–2306. [CrossRef] [PubMed]
Alperin, M., Debes, K., Abramowitch, S., Meyn, L., and Moalli, P. A., 2008, “LOXL1 Deficiency Negatively Impacts the Biomechanical Properties of the Mouse Vagina and Supportive Tissues,” Int. Urogynecol. J., 19(7), pp. 977–986. [CrossRef]
Gibran, N. S., Wiechman, S., Meyer, W., Edelman, L., Fauerbach, J., Gibbons, L., Holavanahalli, R., Hunt, C., Keller, K., Kirk, E., Laird, J., Lewis, G., Moses, S., Sproul, J., Wilkinson, G., Wolf, S., Young, A., Yovino, S., Mosier, M. J., Cancio, L. C., Amani, H., Blayney, C., Cullinane, J., Haith, L., Jeng, J. C., Kardos, P., Kramer, G., Lawless, M. B., Serio-Melvin, M. L., Miller, S., Moran, K., Novakovic, R., Potenza, B., Rinewalt, A., Schultz, J., Smith, H., Dylewski, M., Wibbenmeyer, L., Bessey, P. Q., Carter, J., Gamelli, R., Goodwin, C., Graves, T., Hollowed, K., Holmes, J.4th, Noordenbas, J., Nordlund, M., Savetamal, A., Simpson, P., Traber, D., Traber, L., Nedelec, B., Donelan, M., Baryza, M. J., Bhavsar, D., Blome-EberweinS., Carrougher, G. J., Hickerson, W., Joe, V., Jordan, M., Kowalske, K., Murray, D., Murray, V. K., Parry, I., Peck, M., Reilly, D., Schneider, J. C., Ware, L., Singer, A. J., Boyce, S. T., Ahrenholz, D. H., Chang, P., Clark, R. A., Fey, R., Fidler, P., Garner, W., Greenhalgh, D., Honari, S., Jones, L., Kagan, R., Kirby, J., Leggett, J., Meyer, N., Reigart, C., Richey, K., Rosenberg, L., Weber, J., Wiggins, B., 2013, “American Burn Association Consensus Statements,” J. Burn Care Res., 34(4), pp. 361–385. [CrossRef] [PubMed]
Cua, A., Wilhelm, K. P., and Maibach, H., 1990, “Elastic Properties of Human Skin: Relation to Age, Sex, and Anatomical Region,” Arch. Dermatol. Res., 282(5), pp. 283–288. [CrossRef] [PubMed]
Lanir, Y., 1987, “Skin Mechanics,” Handbook of Bioengineering, R.Skalak and S.Chien, eds., McGraw-Hill, Dallas, TX, pp. 11–25.
Ní Annaidh, A., Bruyère, K., Destrade, M., Gilchrist, M. D., and Otténio, M., 2012, “Characterization of the Anisotropic Mechanical Properties of Excised Human Skin,” J. Mech. Behav. Biomed. Mater., 5(1), pp. 139–148. [CrossRef] [PubMed]
Oxlund, H., Manschot, J., and Viidik, A., 1988, “The Role of Elastin in the Mechanical Properties of Skin,” J. Biomech., 21(3), pp. 213–218. [CrossRef] [PubMed]
Lafrance, H., Yahia, L., Germain, L., Guillot, M., and Auger, F. A., 1995, “Study of the Tensile Properties of Living Skin Equivalents,” Biomed. Mater. Eng., 5(4), pp. 195–208. [CrossRef] [PubMed]
Sander, E. A. and Barocas, V. H., 2008, “Biomimetic Collagen Tissues: Collagenous Tissue Engineering and Other Applications,” Collagen Structure and Mechanics, P.Fratzl, ed., Springer, New York, NY, pp. 475–504.
Grinnell, F., and Petroll, W. M., 2010, “Cell Motility and Mechanics in Three-Dimensional Collagen Matrices,” Ann. Rev. Cell Dev. Biol., 26, pp. 335–361. [CrossRef]
Candi, E., Schmidt, R., and Melino, G., 2005, “The Cornified Envelope: A Model of Cell Death in the Skin,” Nature Rev. Molec. Cell Biol., 6(4), pp. 328–340. [CrossRef]
Fuchs, E., and Cleveland, D. W., 1998, “A Structural Scaffolding of Intermediate Filaments in Health and Disease,” Science, 279(5350), pp. 514–519. [CrossRef] [PubMed]
Ebersole, G., Anderson, P., and Powell, H., 2010, “Epidermal Differentiation Governs Engineered Skin Biomechanics,” J. Biomech., 43(16), pp. 3183–3190. [CrossRef] [PubMed]
Jansen, L., and Rottier, P., 1958, “Some Mechanical Properties of Human Abdominal Skin Measured on Excised Strips,” Dermatol., 117(2), pp. 65–83. [CrossRef]
Berthod, F., Germain, L., Li, H., Xu, W., Damour, O., and Auger, F. A., 2001, “Collagen Fibril Network and Elastic System Remodeling in a Reconstructed Skin Transplanted on Nude Mice,” Matrix Biol., 20(7), pp. 463–473. [CrossRef] [PubMed]
Robb, E. C., Bechmann, N., Plessinger, R. T., Boyce, S. T., Warden, G. D., and Kagan, R. J., “Storage Media and Temperature Maintain Normal Anatomy of Cadaveric Human Skin for Transplantation to Full-Thickness Skin Wounds,” J. Burn Care Res., 22(6), pp. 393–396. [CrossRef]
Holbrook, K. A., and Byers, P. H., 1989, “Skin Is a Window on Heritable Disorders of Connective Tissue,” Am. J. Med. Genet., 34(1), pp. 105–121. [CrossRef] [PubMed]
Bateman, J. F., Boot-Handford, R. P., and Lamandé, S. R., 2009, “Genetic Diseases of Connective Tissues: Cellular and Extracellular Effects of ECM Mutations,” Nature Rev. Genetics, 10(3), pp. 173–183. [CrossRef]
Sander, E. A., Stylianopoulos, T., Tranquillo, R. T., and Barocas, V. H., 2009, “Image-Based Multiscale Modeling Predicts Tissue–Level and Network-Level Fiber Reorganization in Stretched Cell-Compacted Collagen Gels,” Proc. Nat. Acad. Sci. USA, 106(42), pp. 17675–17680. [CrossRef]
Hadi, M. F., Sander, E. A., and Barocas, V. H., 2012, “Multiscale Model Predicts Tissue-Level Failure From Collagen Fiber-Level Damage,” ASME J. Biomech. Eng., 134(9), pp. 091005. [CrossRef]
Sander, E. A., Barocas, V. H., and Tranquillo, R. T., 2011, “Initial Fiber Alignment Pattern Alters Extracellular Matrix Synthesis in Fibroblast-Populated Fibrin Gel Cruciforms and Correlates With Predicted Tension,” Ann. Biomed. Eng., 2011, pp. 1–16 [CrossRef].
Cicchi, R., Kapsokalyvas, D., De Giorgi, V., Maio, V., Van Wiechen, A., Massi, D., Lotti, T., and Pavone, F. S., 2010, “Scoring of Collagen Organization in Healthy and Diseased Human Dermis by Multiphoton Microscopy,” J. Biophotonics,3(1–2), pp. 34–43. [CrossRef]


Grahic Jump Location
Fig. 1

Representative test specimen and loading curve. (a) A dog-bone-shaped sample placed between grips and gauze for uniaxial failure testing. Markers were placed on the surface to facilitate strain analysis if needed (scale = mm). (b) The load-extension curve of an ESS graft depicting where the structural properties of an ESS graft were extracted from, including the ultimate load at failure (N), the maximum extension at failure (mm), the linear stiffness (N/mm) (red-line), and the energy absorbed up to failure (N-mm) (gray area under the curve).

Grahic Jump Location
Fig. 2

Sample histology. Representative histological sections show the progression of engineered skin substitute (ESS) remodeling from (a) an acellular collagen-glycosaminoglycan sponge (CGS), (b) dermal skin substitute (DSS) cultured in vitro two weeks, (c) ESS cultured in vitro two weeks, (d) grafted ESS six weeks post implantation on athymic mice, and compared to (e) mouse autograft, and (f) native mouse skin. Scale bar = 0.5 mm.

Grahic Jump Location
Fig. 3

Grafted ESS and autograft postsurgery. (a) At two weeks postsurgery the grafted ESS is still visible. (b) At six weeks postsurgery the grafted ESS margins are less distinguishable from the surrounding skin. The autograft shows better integration and a better appearance at (c) two weeks that (d) continues to improve so that at six weeks it is difficult to find the margins. Scale is in cm.

Grahic Jump Location
Fig. 4

Averaged load-displacement curves. The averaged sample responses (filled circles) are depicted prior to the point of failure of the first sample in the group. The corresponding standard deviation is indicated by the shaded region. The addition of fibroblasts (DSS) and coculture of fibroblasts and keratinocytes (ESS) increased the stiffness and UTL of the construct before failure occurred. Substantial improvements in mechanical properties developed in six-week grafted ESS. The grafted ESS and autograft were both stiffer and less compliant than the native mouse skin.

Grahic Jump Location
Fig. 5

Structural property boxplots. (a) Linear stiffness, (b) ultimate tensile load, (c) energy, (d) maximum extension for CGS (n = 11), DSS (n = 6), ESS (n = 23), grafted ESS (GESS, n = 5), autograft (AG, n = 8), and intact murine skin (n = 13). Shaded area corresponds to in vivo samples collected from athymic mice at six weeks after grafting. a indicates significant difference (p <0.05) between in vitro group with CGS, b indicates significant difference (p < 0.05) between ESS and DSS. c indicates significant difference (p < 0.05) between grafted ESS and ESS. d indicates significant difference (p < 0.05) between grafted ESS and autograft. e indicates significant difference (p < 0.05) between grafted ESS and ungrafted murine skin. f indicates significant difference (p < 0.05) between autograft and skin.



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