Preparation and characterization of injectable fibrillar type I collagen and evaluation for pseudoaneurysm treatment in a pig model

Objective Despite the efficacy of collagen in femoral artery pseudoaneurysm treatment, as reported in one patient study, its use has not yet gained wide acceptance in clinical practice. In this particular study, the collagen was not described in detail. To further investigate the potential of collagen preparations, we prepared and characterized highly purified injectable fibrillar type I collagen and evaluated its use for femoral artery pseudoaneurysm (PSA) treatment in vivo using a pig model. Methods Purified fibrillar type I collagen was characterized using electron microscopy. The effect of three different sterilization procedures, ie, hydrogen peroxide gas plasma (H 2 O 2 ), ethylene oxide gas (EtO), and gamma irradiation, was studied on both SDS-PAGE and platelet aggregation. Different collagen injectables were prepared (3%, 4%, and 5%) and tested using an injection force test applying a 21-gauge needle. To evaluate the network characteristics of the injectable collagen, the collagen was suspended in phosphate buffered saline (PBS) at 37°C and studied both macroscopically and electron microscopically. To determine whether the collagen induced hemostasis in vivo, a pig PSA model was used applying a 4% EtO sterilized collagen injectable, and evaluation by angiography and routine histology. Results Electron microscopy of the purified type I collagen revealed intact fibrils with a distinct striated pattern and a length 2 O 2 sterilization, although gamma-irradiated collagen showed degradation products. Both 3% and 4% (w/v) collagen suspensions were acceptable with respect to the force used ( Conclusions Collagen injectables were prepared and EtO sterilized without major loss of structural integrity and platelet activity. In vivo, the injectable collagen formed a dense network and triggered (partial) local hemostasis. Although optimization is needed, an injectable collagen may be used as a therapeutic agent for femoral PSA treatment.