Stem/progenitor cells in closed suction drainage fluid after hip arthroplasty

BACKGROUND AND PURPOSE: Drainage after surgery is commonly used, and the contents are generally discarded as clinical waste. We analyzed closed suction drainage fluid from hip arthroplasty patients to determine whether any multipotent stem cells were present that could be used as a source of cells for tissue regeneration. METHODS: Drainage fluid was obtained from 14 patients after hip arthroplasty on the day of surgery, the next day, and 2 days after surgery. Peripheral blood and bone marrow from the iliac crest were also obtained from the same patients during surgery. These samples were examined using regular flow cytometric profiling, and we performed quantitative immunoassays of stromal-derived factor-1 (SDF1) levels in the plasma. Mononuclear cells (MNCs) from these samples were also isolated and cultured. Fibroblastic adherent cells from MNC fractions were cultured in an osteogenic and a chondrogenic differentiation medium and were then evaluated for multipotentency. RESULTS AND INTERPRETATION: Fibroblastic adherent cells were isolated from the mononuclear cell fraction of bone marrow and drainage fluid on the day of surgery, but they were not present in either the mononuclear cell fraction of the peripheral blood or the drainage fluid on the next day and 2 days after surgery. The cells from the drainage fluid on the day of surgery could differentiate in vitro into osteogenic and chondrogenic cells. SDF1 was elevated on the day of surgery, while CXCR4 was elevated on that day and the next day. This suggests that locally-induced SDF1 contributes to the mobilization of circulating CXCR4-positive cells. These results show that the drainage fluid collected on the day of surgery contains stem/progenitor cells that could be used for autologous cell-based therapy.