Histological Reaction of Sintered Nanohydroxyapatite-Coated Cuff and Its Fibroblast-Like Cell Hybrid for an Indwelling Catheter

Rapid tissue-ingrowth of a sintered hydroxyapatite(HAp)-coated and cell-hybrid subcutaneous cuff equipped with an indwelling catheter was developed. The rod-like HAp nanoparticles were coated by covalent bonding on the surface of the silk fibroin (SF) fibers for about 100 mu m of the length. The fibers were transplanted three-dimensionally on a cuff substrate made of silicone elastomer with an adhesive. The fibroblast-like cells, explanted and proliferated from skin tissue containing the epidermis, dermis, and subcutaneous tissue of Japanese white rabbits, were incubated on the three-dimensional cuff for three days. Three types of cuff-polyester, HAp-coated, and cell-hybrid cuffs-were percutaneously implanted into the backs of the same animals for 3 and 7 days. The subcutaneous tissues around the cuff's were stained with hematoxylin-eosin. Immunohistochemical staining to identify macrophages and alpha-smooth muscle actin (alpha-SMA) was also done and examined by light microscopy. The alpha-SMA-positive area was very limited in the polyester cuff group even after 7 days, although many macrophages infiltrated into the fibers. In the cell-hybrid cuff group, on the other hand, an alpha-SMA-positive area was formed extensively after 3 and 7 days, causing severe inflammation. In the HAp-coated cuff group, an alpha-SMA-positive area was formed among the fibers with little inflammation. The extent order of the a-SMA-positive area was cell-hybrid cuff >> HAp-coated cuff >> polyester cuff, while the degree of inflammatory cells order was cell-hybrid cuff >> polyester cuff >> HAp-coated cuff. (C) 2008 Wiley Periodicals. Inc. J Biomed Mater Res Part B: Appl Biomater 89B: 77-85, 2009