title: Reconstitution of the complete rupture in musculotendinous junction using skeletal muscle-derived multipotent stem cell sheet-pellets as a "bio-bond".
abstract: Background. Significant and/or complete rupture in the musculotendinous junction (MTJ) is a challenging lesion to treat because of the lack of reliable suture methods. Skeletal muscle-derived multipotent stem cell (Sk-MSC) sheet-pellets, which are able to reconstitute peripheral nerve and muscular/vascular tissues with robust connective tissue networks, have been applied as a "bio-bond". Methods. Sk-MSC sheet-pellets, derived from GFP transgenic-mice after 7 days of expansion culture, were detached with EDTA to maintain cell-cell connections. A completely ruptured MTJ model was prepared in the right tibialis anterior (TA) of the recipient mice, and was covered with sheet-pellets. The left side was preserved as a contralateral control. The control group received the same amount of the cell-free medium. The sheet-pellet transplantation (SP) group was further divided into two groups; as the short term (4-8 weeks) and long term (14-18 weeks) recovery group. At each time point after transplantation, tetanic tension output was measured through the electrical stimulation of the sciatic nerve. The behavior of engrafted GFP(+) tissues and cells was analyzed by fluorescence immunohistochemistry. Results. The SP short term recovery group showed average 64% recovery of muscle mass, and 36% recovery of tetanic tension output relative to the contralateral side. Then, the SP long term recovery group showed increased recovery of average muscle mass (77%) and tetanic tension output (49%). However, the control group showed no recovery of continuity between muscle and tendon, and demonstrated increased muscle atrophy, with coalescence to the tibia during 4-8 weeks after operation. Histological evidence also supported the above functional recovery of SP group. Engrafted Sk-MSCs primarily formed the connective tissues and muscle fibers, including nerve-vascular networks, and bridged the ruptured tendon-muscle fiber units, with differentiation into skeletal muscle cells, Schwann cells, vascular smooth muscle, and endothelial cells. Discussion. This bridging capacity between tendon and muscle fibers of the Sk-MSC sheet-pellet, as a "bio-bond," represents a possible treatment for various MTJ ruptures following surgery.
authors.affiliation: Department of Orthopaedic, Tokai University School of Medicine, Isehara, Japan; Muscle Physiology and Cell Biology Unit, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Muscle Physiology and Cell Biology Unit, Tokai University School of Medicine, Isehara, Japan; Department of Human Structure and Function, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Tamaki
authors.affiliation: Department of Orthopaedic, Tokai University School of Medicine, Isehara, Japan; Muscle Physiology and Cell Biology Unit, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Hirata
authors.affiliation: Department of Orthopaedic, Tokai University School of Medicine, Isehara, Japan; Muscle Physiology and Cell Biology Unit, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Uchiyama
authors.affiliation: Department of Orthopaedic, Tokai University School of Medicine , Isehara , Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Orthopaedic, Tokai University School of Medicine , Isehara , Japan.
authors.forename: Joji
authors.initials: J
authors.lastname: Mochida
keywords: Muscle contraction; Muscle regeneration; Musculotendinous junction; Nerve reconstitution; Severe muscle injury; Stem cell therapy; Tendon regeneration; Vascular reconstitution