Bioactive polymeric materials and electrical stimulation strategies for musculoskeletal tissue repair and regeneration

Electrical stimulation (ES) is predominantly used as a physical therapy modality to promote tissue healing and functional recovery. Research efforts in both laboratory and clinical settings have shown the beneficial effects of this technique for the repair and regeneration of damaged tissues, which include muscle, bone, skin, nerve, tendons, and ligaments. The collective findings of these studies suggest ES enhances cell proliferation, extracellular matrix (ECM) production, secretion of several cytokines, and vasculature development leading to better tissue regeneration in multiple tissues. However, there is still a gap in the clinical relevance for ES to better repair tissue interfaces, as ES applied clinically is ineffective on deeper tissue. The use of a conducting material can transmit the stimulation applied from skin electrodes to the desired tissue and lead to an increased function on the repair of that tissue. Ionically conductive (IC) polymeric scaffolds in conjunction with ES may provide solutions to utilize this approach effectively. Injectable IC formulations and their scaffolds may provide solutions for applying ES into difficult to reach tissue types to enable tissue repair and regeneration. A better understanding of ES-mediated cell differentiation and associated molecular mechanisms including the immune response will allow standardization of procedures applicable for the next generation of regenerative medicine. ES, along with the use of IC scaffolds is more than sufficient for use as a treatment option for single tissue healing and may fulfill a role in interfacing multiple tissue types during the repair process.