As a suture material, silk fibers are often coated in wax to prevent fraying and potential immune responses. Although silk was thought to cause allergies in some patients, subsequent research has shown that sericin was the cause of the immune responses. Therefore, sericin must be removed from the fibroin to assure biocompatibility. The inflammatory response to silk films was evaluated in vitro with hMSCs or by seeding rat MSCs on the films and implanting them in vivo. The in vitro response to silk fibroin was similar to the response to collagen and tissue culture plastic (TCP) controls. In vivo, silk showed a lower inflammatory response when compared to collagen and PLA. The inflammatory potential has also been assessed in vitro with macrophages where silk was shown to exhibit a similar tumor necrosis factor-alpha (TNF-α), a cytokine indicative of an inflammatory response, levels to that of tissue culture plastic. In addition, silk fibroin has been used in several in vivo studies for brain, soft tissue, subcutaneous, and boneapplications.