An engineered neo-muscle combining regenerative medicine and prosthetics to control artificial limbs

An engineered neo-muscle combining regenerative medicine and prosthetics to control artificial limbs

A scientific collaboration between the Sant'Anna School of Advanced Studies, the INAIL Prosthetic Center, the Rizzoli Orthopaedic Institute and the Italian Institute of Technology (IIT), has developed a new neural interface technology connecting the residual nervous system of a person with an amputation to an artificial prosthesis.

A new neural interface technology has been developed to improve the connection between the residual nervous system of a person with an amputation and an artificial prosthesis. The latest advances at the intersection of regenerative medicine and prosthetics have led to the development of a Regenerative Peripheral Nerve Interface (RPNI), opening up new possibilities for prosthetic control.

The study, published in the international journal Bioactive Materials, is the result of a scientific collaboration between the Sant'Anna School of Advanced Studies in Pisa, the INAIL Prosthetic Center, the Rizzoli Orthopaedic Institute, and the Italian Institute of Technology (IIT). The research team developed an engineered muscle construct by combining myoblasts, stem cell precursors of muscle tissue, with innovative biomaterials. This neo-muscle was subsequently surgically connected to a peripheral nerve in a preclinical model of nerve injury, creating a functional connection between nerve and muscle tissue.

"Our approach integrates advanced tissue engineering strategies with the field of prosthetics. To promote the maturation of muscle tissue and its integration with nerve tissue, we used piezoelectric particles, materials capable of generating electrical signals when subjected to mechanical stimuli. External stimulation was provided through pulsed ultrasound, a non-invasive technology already used in several biomedical fields, but which we have applied in an innovative way in this study," says Leonardo Ricotti, professor at the Sant'Anna School of Advanced Studies and head of the Regenerative Technologies Lab.

The research introduces two major scientific innovations. First, it represents the first documented case of a regenerative peripheral nerve interface created using tissue engineering techniques and subsequently implanted and connected to a peripheral nerve. Second, it demonstrates how the combination of piezoelectric particles incorporated into the muscle construct and ultrasound stimulation can promote both muscle tissue maturation and nerve tissue regeneration.

"This result represents a key step towards the future control of advanced prostheses, as it makes it possible to acquire and amplify signals from the residual nervous system of a person with an amputation and use them to achieve natural and intuitive control," says Christian Cipriani, professor at the Sant'Anna School of Advanced Studies and head of the Artificial Hands Area.

"The researchers' long-term goal is to develop a new generation of bionic prostheses with multiple degrees of freedom that patients can control naturally. In this scenario, a network of regenerative neural interfaces could provide a stable connection between the nervous system and the prosthetic device," says Emanuele Gruppioni, Technical Director of the Research and Training Area at the INAIL Prosthetic Center. "The muscle constructs developed as part of the study could also act as genuine biological amplifiers of nerve signals, enabling increasingly complex movements and significantly improving the quality of life of people with amputations."

"The next challenge is to translate these technologies from research into clinical practice," says Paolo Sassu, orthopaedic surgeon at the Rizzoli Orthopaedic Institute. "Modern bionic limb reconstruction stems precisely from the integration of surgery, neuroengineering and advanced prosthetics: through dedicated surgical procedures, we can create new biological interfaces with the nervous system and make them available for prosthetic control. We are working on this multidisciplinary integration to develop a dedicated programme for bionics and advanced limb reconstruction."

"Bringing advanced characterisation techniques, such as transmission electron microscopy, into an interdisciplinary study of this scope, combining regenerative medicine and prosthetics, was our way of contributing to a complex challenge that opens up new possibilities for the development of prostheses," adds Mauro Gemmi, principal investigator of the Electron Crystallography Unit at the Italian Institute of Technology (IIT).

Ultrasound-activated piezoelectric muscle constructs for tissue-engineered regenerative peripheral nerve interfaces