Biochemical and mechanical environment cooperatively regulate skeletal muscle regeneration

Abstract

During forelimb regeneration in the newt Notophthalmus viridescens, the dynamic expression of a transitional matrix rich in hyaluronic acid, tenascin-C, and fibronectin controls muscle cell behavior in vivo and in vitro. However, the influence of extracellular matrix (ECM) remodeling on tissue stiffness and the cellular response to mechanical variations during regeneration was unknown. By measuring the transverse stiffness of tissues in situ, we found undifferentiated regenerative blastemas were less stiff than differentiated stump muscle (13.3±1.6 vs. 16.6±1.2 kPa). To directly determine how ECM and stiffness combine to affect skeletal muscle fragmentation, migration, and fusion, we coated silicone-based substrates ranging from 2 to 100 kPa with matrices representative of transitional (tenascin-C and fibronectin) and differentiated environments (laminin and Matrigel). Using live-cell imaging, we found softer tenascin-C-coated substrates significantly enhanced migration and fragmentation of primary newt muscle cells. In contrast, stiffer substrates coated with laminin, Matrigel, or fibronectin increased differentiation while suppressing migration and fragmentation. These data support our in vivo observations that a transitional matrix of reduced stiffness regulates muscle plasticity and progenitor cell recruitment into the regenerative blastema. These new findings will enable the determination of how biochemical and mechanical cues from the ECM control genetic pathways that drive regeneration.

Acute and Temporal Expression of Tumor Necrosis Factor (TNF)-α-stimulated Gene 6 Product, TSG6, in Mesenchymal Stem Cells Creates Microenvironments Required for Their Successful Transplantation into Muscle Tissue

“…1; Table 1). The environment of the host tissue is essential for successful transplantation (10,11,26).…”

Looking Ahead to Engineering Epimorphic Regeneration of a Human Digit or Limb

“…[59][60][61] This protein assembly is compliant and provides directional guidance (reviewed in Christensen and Tassava 41 and Thornton 62 ) and cues that allows proliferation and cell migration. 63,64 Other microenvironmental factors, such as fibroblast growth factor (FGF), BDGF, and GGF2, arise from interdependent signaling between the AEC and neuronal structures. 39 The resulting physiochemical environment regulates the processes of blastema formation, 48 proliferation, and dedifferentiation.…”

Vascular smooth muscle cell durotaxis depends on extracellular matrix composition

“…Stiffness mapping experiments have shown that plaque stiffness is spatially heterogeneous, and that these changes can be histologically related to the ECM composition of the plaque (20,25). Given the increasing number of examples for which changes in ECM composition in disease are coupled to changes in mechanical properties of the diseased tissue, there is a need for in vitro experimental systems that allow for systematic exploration of how the cellular response to stiffness gradients is modulated by ECM composition.Recent experimental work has demonstrated that the effect of matrix stiffness on cell behaviors such as differentiation, spreading, and motility is modulated by the composition of the ECM on which the cells are grown (26)(27)(28)(29)(30). Though the role of matrix composition has been investigated on uniformly stiff substrates, previous work investigating the cellular response to mechanical gradients has been limited to substrates coated with a single type of matrix protein, typically collagen or fibronectin (31), and the behavioral response of a given cell type to different matrix compositions has yet to be explored in the same study.…”

“…Recent experimental work has demonstrated that the effect of matrix stiffness on cell behaviors such as differentiation, spreading, and motility is modulated by the composition of the ECM on which the cells are grown (26)(27)(28)(29)(30). Though the role of matrix composition has been investigated on uniformly stiff substrates, previous work investigating the cellular response to mechanical gradients has been limited to substrates coated with a single type of matrix protein, typically collagen or fibronectin (31), and the behavioral response of a given cell type to different matrix compositions has yet to be explored in the same study.…”