Biotechnology and Bioprocess Engineering 2008, 13: 745-751 DOI/10.1007/s12257-008-0118-0  Reinforced Bioartificial Dermis Constructed with Collagen Threads Young-Kwon Seo 1 , Hee-Hun Youn 1 , Chang-Seo Park 2 , Kye-Yong Song 3 , and Jung-Keug Park 1,4 * 1 Dongguk University Research Institute of Biotechnology, Dongguk University, Seoul 100-715, Korea 2 Department of Chemical and Biochemical Engineering, Dongguk University, Seoul 100-715, Korea 3 Department of Pathology, Chung-Ang University, Seoul 156-756, Korea 4 Department of Medical Biotechnology, Dongguk University, Seoul 100-715, Korea Abstract In this work, a novel type of composite scaffold was designed, which has the suitability of both high biocompatibility and strong mechanical properties, for use in bioartificial dermis applications. The reinforced scaffold consisted of a lyophilized collagen sponge formed around a cross-linked collagen meshwork with an average thread diameter of approximately 55 μm. Fibroblasts were cultured in the reinforced collagen sponge for 7 days, during which time the pores in the sponge became filled with cells that secreted extracellular matrix (ECM) to form a bioartificial dermis. Results of ultimate tensile strength (UTS) measurements and compression tests indicated that the bioartificial dermis formed around the reinforced collagen sponge showed about ten times the strength of the bioartificial dermis formed around a typical collagen sponge (1.5 ± 0.05 vs. 0.15 ± 0.05 and 2.5 ± 0.1 vs. 0.2 ± 0.08 MPa, respectively). As a result, reinforced collagen mesh improved mechanical properties and this technique will be possible to make stronger scaffolds, not only for artificial skin applications but also vari- ous artificial tissues, such as synthetic cartilage, bone, and blood vessels. © KSBB Keywords: reinforce, collagen thread, collagen sponge, tissue engineering INTRODUCTION Various types of skin equivalents have been developed to cover skin defects caused by burns and other types of trauma. Rheinwald and Green developed a culture of keratinocytes using a 3T3 feeder layer, but the survival rate of cultured epithelial autografts (CEAs) in full-thickness skin defects is relatively low. The graft can fail to take when CEAs and autografts are applied to a wound surface in poor condition without a dermis. Moreover, there is a risk of poor epitheli- zation due to the absence of a dermal component at the re- cipient site. Therefore, a dermal equivalent is required to overcome this problem. Scar tissue formation can be reduced with the use of a living skin equivalent consisting of com- bined dermal equivalent and cultured epithelial layers. The non-cellular components of the dermis, which primar- ily consist of extracellular matrix (ECM) proteins and colla- gen, have been shown to be relatively non-immunogenic. The acellular human dermis (i.e. AlloDerm) is the first commercially available human collagen material in sheet form, which offers the real possibility for use as a collagen *Corresponding author Tel: +82-2-2260-3365 Fax: +82-2-2271-3489 e-mail: jkpark@dongguk.edu scaffold and can be replaced by native collagen [1]. The original method of Yannas and Burke for the use of artificial skin has been commercialized (Integra TM , Integra Life Sci- ences Co., San Diego, CA, USA). Their artificial skin was a bilayer membrane, composed of a dermal portion consisting of a porous matrix formed from lyophilized collagen cross- linked with chondroitin-6-sulphate [2-4]. The other commer- cially available wound-healing product is Dermagraft TM (Ad- vanced Tissue Science, Inc., La Jolla, CA, USA), which is currently been marketed in Canada, the United Kingdom, and other European countries for the treatment of diabetic foot ulcers. Dermagraft TM is a metabolically active dermal skin replacement, containing various ECM components and grow th factors normally found in human dermis. This artificial skin product is produced by seeding dermal allogenic fibroblasts onto a three-dimensional scaffold consisting of polyglycolic acid (PGA) and polyglactin-910 (PLA) fibers [5,6]. Previous tissue engineering studies have been performed using a combination of cells, growth factors, and scaffolds [7,8]. Wound healing is achieved by the synergistic effect of these three components, all of which play important roles. Scaffolds provide the substrates to which the cells can attach during the initial phase, and degrade after the completion of wound healing. Consequently, various scaffolds having been investigated, including gelatin, alginate, chitosan, hyaluro-