Pavlath G K, Thaloor D, Rando T A, Cheong M, English A W, Zheng B
Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Dev Dyn. 1998 Aug;212(4):495-508. doi: 10.1002/(SICI)1097-0177(199808)212:4<495::AID-AJA3>3.0.CO;2-C.
Skeletal muscle has a remarkable capacity to regenerate after injury, although studies of muscle regeneration have heretofore been limited almost exclusively to limb musculature. Muscle precursor cells in skeletal muscle are responsible for the repair of damaged muscle. Heterogeneity exists in the growth and differentiation properties of muscle precursor cell (myoblast) populations throughout limb development but whether the muscle precursor cells differ among adult skeletal muscles is unknown. Such heterogeneity among myoblasts in the adult may give rise to skeletal muscles with different regenerative capacities. Here we compare the regenerative response of a masticatory muscle, the masseter, to that of limb muscles. After exogenous trauma (freeze or crush injuries), masseter muscle regenerated much less effectively than limb muscle. In limb muscle, normal architecture was restored 12 days after injury, whereas in masseter muscle, minimal regeneration occurred during the same time period. Indeed, at late time points, masseter muscles exhibited increased fibrous connective tissue in the region of damage, evidence of ineffective muscle regeneration. Similarly, in response to endogenous muscle injury due to a muscular dystrophy, widespread evidence of impaired regeneration was present in masseter muscle but not in limb muscle. To explore the cellular basis of these different regenerative capacities, we analyzed the myoblast populations of limb and masseter muscles both in vivo and in vitro. From in vivo analyses, the number of myoblasts in regenerating muscle was less in masseter compared with limb muscle. Assessment of population growth in vitro indicated that masseter myoblasts grow more slowly than limb myoblasts under identical conditions. We conclude that the impaired regeneration in masseter muscles is due to differences in the intrinsic myoblast populations compared to limb muscles.
骨骼肌在受伤后具有显著的再生能力，尽管迄今为止对肌肉再生的研究几乎完全局限于肢体肌肉组织。骨骼肌中的肌肉前体细胞负责受损肌肉的修复。在整个肢体发育过程中，肌肉前体细胞（成肌细胞）群体的生长和分化特性存在异质性，但成体骨骼肌中的肌肉前体细胞是否存在差异尚不清楚。成体中这些成肌细胞之间的异质性可能导致具有不同再生能力的骨骼肌。在这里，我们比较了咀嚼肌（咬肌）与肢体肌肉的再生反应。在受到外部创伤（冷冻或挤压伤）后，咬肌的再生效果远不如肢体肌肉。在肢体肌肉中，损伤后12天恢复了正常结构，而在咬肌中，在同一时期内几乎没有再生。事实上，在后期，咬肌在损伤区域出现了纤维结缔组织增加的情况，这是肌肉再生无效的证据。同样，在因肌肉营养不良导致的内源性肌肉损伤中，咬肌中存在广泛的再生受损证据，而肢体肌肉中则没有。为了探究这些不同再生能力的细胞基础，我们在体内和体外分析了肢体肌肉和咬肌的成肌细胞群体。从体内分析来看，与肢体肌肉相比，再生肌肉中咬肌的成肌细胞数量较少。体外群体生长评估表明，在相同条件下，咬肌成肌细胞的生长速度比肢体成肌细胞慢。我们得出结论，咬肌再生受损是由于与肢体肌肉相比，其内在成肌细胞群体存在差异。
