A Rat Model for Muscle Regeneration in the Soft Palate

Abstract

BackgroundChildren with a cleft in the soft palate have difficulties with speech, swallowing, and sucking. Despite successful surgical repositioning of the muscles, optimal function is often not achieved. Scar formation and defective regeneration may hamper the functional recovery of the muscles after cleft palate repair. Therefore, the aim of this study is to investigate the anatomy and histology of the soft palate in rats, and to establish an in vivo model for muscle regeneration after surgical injury.MethodsFourteen adult male Sprague Dawley rats were divided into four groups. Groups 1 (n = 4) and 2 (n = 2) were used to investigate the anatomy and histology of the soft palate, respectively. Group 3 (n = 6) was used for surgical wounding of the soft palate, and group 4 (n = 2) was used as unwounded control group. The wounds (1 mm) were evaluated by (immuno)histochemistry (AZAN staining, Pax7, MyoD, MyoG, MyHC, and ASMA) after 7 days.ResultsThe present study shows that the anatomy and histology of the soft palate muscles of the rat is largely comparable with that in humans. All wounds showed clinical evidence of healing after 7 days. AZAN staining demonstrated extensive collagen deposition in the wound area, and initial regeneration of muscle fibers and salivary glands. Proliferating and differentiating satellite cells were identified in the wound area by antibody staining.ConclusionsThis model is the first, suitable for studying muscle regeneration in the rat soft palate, and allows the development of novel adjuvant strategies to promote muscle regeneration after cleft palate surgery.

Fibrosis impairs the formation of new myofibers in the soft palate after injury

“…The aim of this study was to evaluate the regeneration of myofibers and the development of fibrotic tissue after injury. We previously demonstrated that the anatomy and histology of the soft palate muscles of the rat are largely comparable to that of humans . Here, we show for the first time that muscle regeneration in the soft palate of the rat after excisional injury is incomplete.…”

“…As previously described, the animals received buprenorphine (0.02 mg/kg s.c.; Temgesic, Schering Plough, Brussels, Belgium) as an analgesic before surgery and at 12‐hour intervals for the next 2 days. Briefly, animals in groups 2–5 were anesthetized and placed on an operating table in a supine position for surgery.…”

“…Sections were stained as described previously . The following primary antibodies were used: mouse anti‐Pax7 (1: 100; Developmental Studies Hybridoma Bank, Iowa City, IA), mouse anti‐MyoD (1 : 50; DAKO, Dakopatts, Glostrup, Denmark), mouse anti‐myogenin (1 : 100; DSHB), mouse anti‐alpha‐smooth muscle actin (α‐SMA, 1 : 10,000; Chemical Co., St Louis, MO), and mouse anti‐fast MyHC (1 : 5,000; Sigma Chemical Co.).…”

Tissue engineering strategies combining molecular targets against inflammation and fibrosis, and umbilical cord blood stem cells to improve hampered muscle and skin regeneration following cleft repair

“…Muscle repair following injury is facilitated by SCs. Satellite cells are muscle stem cells originating from the CPM that are responsible for postnatal muscle growth, maintenance, and repair . They express the paired box transcription factor 7 (Pax7) and are located between the sarcolemma and basal lamina surrounding a single muscle fiber.…”

“…They express the paired box transcription factor 7 (Pax7) and are located between the sarcolemma and basal lamina surrounding a single muscle fiber. After the injury, SCs become activated and migrate to the site of injury, proliferate, and differentiate into myoD‐positive myoblasts that fuse to form new multinucleated myosin heavy chain (MyHC)‐positive myofibers or repair damaged myofibers (Figure ) . A small portion of these SCs stay quiescent to allow future regeneration cycles.…”