Musculoskeletal tissue engineering (MTE) has proven to stimulate survival and differentiation of myoblasts towards tissue regeneration both in vitro and in vivo (1). In this field, different polymeric biomaterials have been employed to provide a biomimetic environment where cells can proliferate and differentiate into muscle tissue.
Polycaprolactone (PCL) is a synthetic aliphatic biodegradable polymer with remarkable mechanical properties, thermal stability, and controllable degradation. It is also approved by the FDA as a biomaterial for biomedical applications, being used in a wide range of biomedical applications, such as tissue engineering, dental implants, and drug delivery. (2,3, 4). PCL-based muscular grafts are promising tools in MTE (3).
Musculoskeletal tissue is well known for its electrosensitive cells since it is innerved by motoneurons that stimulate muscle myofibers to contract. Therefore, it is of great interest to obtain electrically active cell substrates to assess their influence in cell differentiation with and without external electrical stimulation. Different polymeric nanocomposites with conductive particles have been developed in recent years (5). Graphene (G), a polycyclic aromatic hydrocarbon with excellent conductive properties, has been incorporated as a filler to obtain electrically active biomaterials for MTE applications (6,7).
In addition, the role of different bioactive factors in combination with polymeric scaffolds have been deeply studied for MTE (1). Therapeutic inorganic ions, such as calcium (Ca2+) and zinc (Zn2+), are being studied in applications of tissue regeneration since they induce regeneration avoiding the drawbacks of growth factors (immunogenicity problems, risk of cancer and alterations in cellular homeostasis). In particular, Zn2+, a relevant metallic element in the human body, has been shown to induce proliferation, differentiation, and migration of cells, accelerating in vitro muscle formation (8). It was also proved that extracellular Zn2+ enhances myogenic differentiation by the activation of the Akt signaling pathway (9).
In this study, we hypothesise that bioactive cell environments based on electroactive nanohybrid biomaterials together with Zn2+ ions can synergistically stimulate myogenic differentiation. Conductive PCL/G nanocomposites were prepared with different amounts of G nanoparticles and a non-cytotoxic concentration of extracellular Zn2+ (40 µM) was chosen to analyse its effects in myogenic differentiation with murine myoblasts. The results show that the combination of conductive substrates and extracellular Zn2+ ions (PCL/G/Zn) increases myogenic differentiation in a significant way. However, further studies are needed to explore their full potential in MTE.
Financial support from the Spanish Ministry of Science and Innovation (MCINN, AEI/FEDER funds) through the project RTI2018-097862-B-C21 is acknowledged.
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