MMP1 Gene Transfer Enhances Myoblast Migration And Engraftment In mdx/SCID Mice
Myoblast transplantation (MT) is a method to introduce healthy genes into diseased muscles such as Duchenne Muscular Dystrophy (DMD), and have been considered a therapeutic modality in the last decades. However, challenges including cell death and poor engraftment have limited the application. Matrix metalloproteinase type 1 (MMP1), a naturally occurring collagen-digesting enzyme, which specifically digests collagens, types I&III, can eliminate existing fibrotic scarring in different tissues including limb muscles. Our previous studies have discovered MMP1 could improve tissue healing by reversing fibrotic scar tissues and enhancing muscle regeneration in traumatically injured skeletal muscles. We also determined that MMP1 can enhance MT into the dystrophic muscle of mdx mice, a dystrophic skeletal muscle murine model. Our recent study also uncovered the essential benefits of MMP1 in the behaviors of muscle satellite cells and stem cells. Thus, we hypothesize the utilized gene transfer techniques will extend MMP function and improve its efficacy during MT into the diseased dystrophic muscles. A retroviral vector, pLNCX2 (Retroviral Vector, CLONETECH) was selected to encode the full-length human MMP1 gene and was then used to transduce C2C12 myoblasts. Our results indicated MMP1 expression successfully promotes myogenic differentiation/fusion and activates migrations of C2C12 in vitro, as well as improves engraftment of dystrophin-positive myofibers after implantation in vivo. The current study goals to identify a novel technique to apply to improve the delivery of dystrophin gene into the dystrophic muscles, as expecting this technical approach would increase the clinical applicability of MT to the injured and diseased skeletal muscles.