JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE RESEARCH ARTICLE J Tissue Eng Regen Med 2010; 4: 55–61. Published online 14 October 2009 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/term.218 In situ adipogenesis in fat tissue augmented by collagen scaffold with gelatin microspheres containing basic fibroblast growth factor Yu Kimura 1 , Wakako Tsuji 2 , Hiroyasu Yamashiro 2 , Masakazu Toi 2 , Takashi Inamoto 3 and Yasuhiko Tabata 1 * 1 Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan 2 Department of Surgery, Graduate school of Medicine, Kyoto University, Kyoto, Japan 3 Department of Breast Surgery, Kitano Hospital, Tazuke Kofukai Medical Research Institute, Osaka, Japan Abstract In situ adipose tissue regeneration in fat tissue by collagen sponges and gelatin microspheres containing basic fibroblast growth factor (bFGF) was investigated. A minced collagen sponge scaffold (1 ml) was incorporated with microspheres containing 10 μg bFGF and administered into a defect of rabbit fat tissues. Adipogenesis at the administered site was evaluated histologically. The adipose tissue regeneration induced by the administration of mixed collagen scaffold and microspheres containing bFGF was significantly stronger than that of either collagen scaffold alone or microspheres containing bFGF alone. The histological area of in situ adipogenesis by the mixed collagen scaffold and microspheres containing bFGF was enhanced over time by repeated administration. It is concluded that the repeated administration of collagen scaffold and microspheres containing bFGF is a promising way to achieve adipose tissue regeneration inside inherent fat tissue. This technique might be applicable for the reconstruction of volume contour deformities by trauma or surgical interventions of adipose tissue in a minimally invasive manner. Copyright  2009 John Wiley & Sons, Ltd. Received 20 February 2009; Revised 21 August 2009; Accepted 21 August 2009 Keywords adipogenesis; rabbit; scaffold; controlled release; collagen; bFGF; gelatin 1. Introduction Mastectomy accompanied by the excision of breast cancer results in the loss of one or both breasts, which has often caused severe mental problems for patients. To address these problems, trials of breast reconstruction have been clinically performed (Rosen and Hugo, 1988; Carlson, 1994; Chan et al., 2008). Normally, the autograft of fat tissue has been used in plastic and reconstructive surgery for the augmentation of soft tissues, as treatment for breast cancer excision or volume contour deformities after trauma or surgical interventions (Billings and May, 1989). Despite the wide application of such a free-fat *Correspondence to: Yasuhiko Tabata, 53 Kawara-cho Shogoin, Sakyo-ku, Kyoto, 6068507, Japan. E-mail: yasuhiko@frontier.kyoto-u.ac.jp autograft, the progressive absorption of grafted tissue remains unresolved (Ersek, 1991; Fagrell et al., 1996). Microscopic examination of free-fat autografts shows the necrosis of adipocytes (Smahel, 1989). On the other hand, artificial implants such as silicone and saline prostheses have been used clinically but several adverse effects accompany all of the procedures (Broder and Cohen, 2006). Recently, tissue engineering as a substitute for reconstructive surgery and organ transplantation has been recognized as a newly emerging biomedical technology and methodology to regenerate and repair a body defect by combining cells of high proliferation and differentiation potential with an artificial matrix of cells, scaffold and growth factors (Langer, 2007). This tissue-engineering technology is also applicable to the regeneration of adipose tissue, and many experimental trials of adipose tissue engineering have been reported (Patrick, 2004; Copyright  2009 John Wiley & Sons, Ltd.