Evaluation of biocompatibility and biodegradability of a new auto-derived injectable soft tissue filler: a preliminary report

Although a wide range of materials has been used as implants in reconstructive or cosmetic surgery, many implant materials proved to be of limited usefulness due to lack of stability or result in host immune response. The purpose of this study is to explore a new autogenous injectable soft-tissue filler derived from hair and evaluate the possible use of this potential filling agent. Hair fibers after bleaching were processed into different size particles by a ball mill or hair keratin gel, respectively. The microstructure of material was observed under electron microscopy. General toxic tests in vitro or in vivo include MTT assay, acute toxicity, and the micronucleus were used to evaluate the biocompatibility of this material. Animal subcutaneous implant models were employed to investigate the immune reaction, absorption, and maintenance of the augmentation effect. Hair-derived material after processing showed an intrinsic capacity with preferable fluidity and glutinousness for injection. General toxic evaluation revealed a good biocompatibility and an absence of cytotoxicity or mutagenicity. Animal subcutaneous implant models did not show local or systemic adverse reactions in the observation period. Hair fiber particles showed preferable augmentation effect which preserved at least 50% of original volume during the observation period compared to hair keratin gel. The optimal size of the particle is about 120 mu m. The autogenous hair material directly processed by the ball mill after bleaching is easy to obtain and shows biocompatibility and biodegradability well. It may become a prospective filling agent in reconstructive or cosmetic surgery.