Porcine bladder acellular matrix porosity: impact of hyaluronic acid and lyophilization.

Bladder acellular matrix (ACM) is being investigated as a urinary bladder replacement scaffold. We have demonstrated that ACM is porous and theorized that this contributes to ACM fibrosis and contracture over time in vivo and may preclude uptake and retention of molecules, which may aid cellular repopulation. We sought to determine if hyaluronic acid (HA) would decrease ACM porosity. Porcine ACM was lyophilized and rehydrated in HA (SIGMA) to form the hybrid HA-ACM construct. Three groups (n = 15/group: HA-ACM, ACM, and lyophilized/rehydrated ACM) were tested for porosity to a 10 cm column of distilled water, measuring the effluent hourly for 3 h. A porosity index was determined as the total effluent divided by time and area (cc/cm2 hr). Alcian blue staining and fluorophore-assisted carbohydrate electrophoresis qualitatively and quantitatively confirmed the uptake of HA. HA-ACM and lyophilized/rehydrated ACM were significantly less porous to water than untreated ACM [mean (+/-SE): 0.09 (+/-0.02), 0.74 (+/-0.4), and 9.8 (+/-1.6) cc/cm2 hr, respectively; Mann Whitney p < 0.0001 (HA) and p < 0.0001 (lyo)]. The difference between HA-ACM and lyophilized ACM was also statistically significant (p = 0.014). ACM hybridization with HA decreases ACM porosity, in part because of ACM lyophilization during the hybridization process. In future applications, HA may function as a carrier for smaller molecules such as growth factors, and as a bioactive molecule to improve wound healing and decrease fibrosis in tissue-engineered bladder constructs. (c) 2005 Wiley Periodicals, Inc.