In vivo injectable gels for tissue repair.

The desire to reduce healthcare costs while improving outcomes drives minimally invasive methods to replacing traditional surgical procedures. Various treatments that would previously have needed open-type surgeries can be carried out using endoscopes, catheters, and needles. These advantages have become especially obvious for tissue engineering and regenerative medicine with in vivo gel injectable nanomaterials. In this review, the state of the art in this rapidly developing field is given. This is done by contrasting functional evaluation in vitro with in vivo followed by describing (1) synthetic materials, (2) the body's own polymers, (3) polymers in nature, (4) self-assembled peptides, and (5) new innovations and combinations. With increased understanding of the relationship between material characteristics and the outcome in vivo more rational design criteria are emerging.