Injectable biomaterials as minimal invasive strategy towards soft tissue regeneration—an overview

Soft tissue engineering has been gaining increasing interest as an approach to overcome the limitations posed by current clinical procedures such as invasiveness of the surgery, post-operative complications and volume loss. Soft tissue damage occurs either due to congenital malformation, trauma/disease or surgical resection. Through the use of autologous cells, such as mesenchymal stem cells, combined with a biomaterial acting as a support, biological substitutes can be developed. A promising pathway in terms of delivery of these engineered constructs is the use of an injectable system, able to provide a minimally invasive approach. Advances have been made in the development of biocompatible biomaterials able to induce soft tissue regeneration. The present review provides an overview of fillers used in the clinic as well as a non-exhaustive overview of all injectable systems reported for soft tissue engineering. A particular focus is placed on the benefits and drawbacks of the biomaterials and the underlying polymerisation strategy. Furthermore, focus is placed on the mechanical properties of the systems.