Interleukin-10 plasmid delivery by polymeric nanocarrier shows efficient and safe tissue repair in acute muscle damage models in mice

We established a custom-designed nanocarrier for in vivo delivery of an immunomodulatory plasmid capable of facilitating tissue repair in acute muscle damage models in mice. The nanocarrier was constructed by selecting from versatile cationic designs that were used to complex with a negatively charged plasmid, while the excessive positive charge was shielded by the poly (glutamic acid)-polyethylene glycol co-polymer. The best-performing formulation was identified by high throughput screening in macrophages, in which we obtained the hierarchical ranking in terms of reporter gene expression (GFP plasmid, pGFP) and macrophage polarization status (interleukin 10 plasmid, pIL-10). For proof-of-principle, we performed intramuscular (IM) injection of pGFP nanocarrier in a cardiotoxin-induced muscle injury model. After confirming the in vivo GFP transfection, we demonstrated protected delivery of pIL-10 to the injured muscle site, leading to an accelerated tissue repair outcome. Immunophenotyping analysis revealed the increased number of M2 macrophages and regulatory T cells, as well as increased IL-10 production at muscle site. The effectiveness of the pIL-10 carrier was interfered by pharmaceutical macrophage depletion using pre-injected clodronate liposome. When intravenously (IV) injected, our pIL-10 nanocarrier preferentially biodistributed in the injured muscle (owing to transiently decreased blood vessel integrity) and improved tissue repair. Unlike IL-10 protein (that was clinically abandoned), sustained IL-10 production by our nanocarrier dramatically reduced the degree of spleen enlargement and kidney inflammation, suggesting a favorable safety characteristic in vivo.