2016) Characterization and implantation of a novel foamy type of collagen into SD rats to regenerate tissue by slowing down the collagen degradation rate, International Journal of Polymeric Materials and Polymeric Biomaterials, 65:10, 508-515To link to this article: http://dx. ABSTRACTCollagen has high biocompatibility and biodegradability and therefore is an ideal natural polymer biomaterial for tissue regeneration, such as gel-like and porous collagens. However, the limitation of gel-like collagen is unsuitability for cell/tissue ingrowth and the limitation of porous collagen is quick degradation rate. Here, the authors propose a novel type of foamy collagen to address the previous limitations. Foamy collagen with a closed/nonconnective porous structure was formed using foaming technology and not using toxic crosslinking reagents. This research aimed to investigate the macro-/ microstructure, the in vitro/vivo degradation rate, and the tissue regeneration feasibility of foamy collagen. For in vitro degradation rate, porous collagen was completely degraded by enzyme, whereas 91.5% and 72.1% of gel-like and foamy collagens, respectively, remained intact. In vivo degradation rate had a similar trend as in vitro data. After implantation of the collagens in Sprague Dawley rats, immune cells were observed at the periphery of the three types of collagen at day 3. Fibroblast ingrowth was observed in foamy and porous collagen groups at day 7. Neocapillary formation and tissue regeneration were observed in foamy and porous collagen groups at day 14, but nearly none in gel-like collagen group. In conclusion, the authors believe that foamy collagen is promising for application of soft-tissue regeneration. GRAPHICAL ABSTRACT ARTICLE HISTORY