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Bone marrow-derived cell regulation of skeletal muscle regeneration.

Sun D, Martinez CO, Ochoa O, Ruiz-Willhite L, Bonilla JR, Centonze VE, Waite LL, Michalek JE, McManus LM, Shireman PK - FASEB J. (2008)

Bottom Line: Limb regeneration requires the coordination of multiple stem cell populations to recapitulate the process of tissue formation.Thus, the expression of CCR2 on BM-derived cells regulated macrophage recruitment into injured muscle, numbers of MPC, and the extent of regenerated myofiber size, all of which were independent of CCR2 expression on host-derived cells.Future studies in regenerative medicine must include consideration of the role of BM-derived cells, possibly macrophages, in CCR2-dependent events that regulate effective skeletal muscle regeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, University of Texas Health Science Center, San Antonio, Texas, USA.

ABSTRACT
Limb regeneration requires the coordination of multiple stem cell populations to recapitulate the process of tissue formation. Therefore, bone marrow (BM) -derived cell regulation of skeletal muscle regeneration was examined in mice lacking the CC chemokine receptor 2 (CCR2). Myofiber size, numbers of myogenic progenitor cells (MPCs), and recruitment of BM-derived cells and macrophages were assessed after cardiotoxin-induced injury of chimeric mice produced by transplanting BM from wild-type (WT) or CCR2(-/-) mice into irradiated WT or CCR2(-/-) host mice. Regardless of the host genotype, muscle regeneration and recruitment of BM-derived cells and macrophages were similar in mice replenished with WT BM, whereas BM-derived cells and macrophage accumulation were decreased and muscle regeneration was impaired in all animals receiving CCR2(-/-) BM. Furthermore, numbers of MPCs (CD34(+)/Sca-1(-)/CD45(-) cells) were significantly increased in mice receiving CCR2(-/-) BM despite the decreased size of regenerated myofibers. Thus, the expression of CCR2 on BM-derived cells regulated macrophage recruitment into injured muscle, numbers of MPC, and the extent of regenerated myofiber size, all of which were independent of CCR2 expression on host-derived cells. Future studies in regenerative medicine must include consideration of the role of BM-derived cells, possibly macrophages, in CCR2-dependent events that regulate effective skeletal muscle regeneration.

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BM-derived cells define early inflammation after skeletal muscle injury. Representative results were derived from injured skeletal muscle from chimeric mice at 3 or 7 days after CTX; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A–C, G–I) host control groups. D–F, J–L) experimental groups. Most Mac3+ and CD68+ positive cells identified by immunohistochemical analysis (red signal) were also GFP+ (green signal) and in combination, appeared as an orange signal; these cells were abundant in host mice receiving WT BM (A–F). Few Mac3+, CD68+, or GFP+ cells were present in host mice receiving CCR2−/− BM (G–L). Confocal image with nuclei identified by DAPI (blue).
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Figure 2: BM-derived cells define early inflammation after skeletal muscle injury. Representative results were derived from injured skeletal muscle from chimeric mice at 3 or 7 days after CTX; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A–C, G–I) host control groups. D–F, J–L) experimental groups. Most Mac3+ and CD68+ positive cells identified by immunohistochemical analysis (red signal) were also GFP+ (green signal) and in combination, appeared as an orange signal; these cells were abundant in host mice receiving WT BM (A–F). Few Mac3+, CD68+, or GFP+ cells were present in host mice receiving CCR2−/− BM (G–L). Confocal image with nuclei identified by DAPI (blue).

Mentions: In the control, NS-injected muscle of all groups, there were rare foci of skeletal muscle regeneration, a pattern consistent with muscle damage from the needle used for injection. After CTX injury, however, the genotype of the BM donor determined the histological appearance of the muscle; that is, both groups of host mice receiving WT BM had a similar histological appearance, whereas both groups of host mice receiving CCR2−/− BM were comparable. Of importance, there were distinctly different histological patterns, depending on the genotype of the BM donor. Thus, at 3 days after CTX injury, a robust, predominately mononuclear, inflammatory infiltrate was evident within injured muscle in all host mice receiving WT BM (Fig. 1A, D). The majority of these mononuclear cells were of donor BM origin as indicated by the presence of GFP and were strongly positive for multiple macrophage markers, Mac3 and CD68 (Fig. 2A, B, D, E) as well as F4/80 (not shown). The histological patterns were similar using all 3 macrophage markers, and cells positive for macrophage markers were generally also positive for GFP. Although still abundant, cells positive for macrophage markers were decreased at day 7 (Fig. 2C, F) compared with day 3 after CTX injury. Small, regenerated muscle fibers were present at day 7 (Fig. 1B, E). In contrast, host mice receiving CCR2−/− BM exhibited minimal mononuclear cell infiltrates at both day 3 (Fig. 1G, J) and day 7 (Fig. 1H, K) after CTX treatment; consistent with this histological pattern, few GFP+, Mac3+, or CD68+ cells were present at day 3 (Fig. 2G, H, J, K) or day 7 (Fig. 2I, L). At both days 3 and 7 after CTX treatment, the extent of infiltrating cells in mice receiving CCR2−/− BM remained substantially less than that of mice receiving WT BM. In all chimeric groups at 21 days after injury, regenerated fibers were widespread and identified by the presence of centrally located nuclei; however, muscle fiber size appeared to be larger in host mice receiving WT BM (Fig. 1C, F) than in host mice receiving CCR2−/− BM (Fig. 1I, L).


Bone marrow-derived cell regulation of skeletal muscle regeneration.

Sun D, Martinez CO, Ochoa O, Ruiz-Willhite L, Bonilla JR, Centonze VE, Waite LL, Michalek JE, McManus LM, Shireman PK - FASEB J. (2008)

BM-derived cells define early inflammation after skeletal muscle injury. Representative results were derived from injured skeletal muscle from chimeric mice at 3 or 7 days after CTX; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A–C, G–I) host control groups. D–F, J–L) experimental groups. Most Mac3+ and CD68+ positive cells identified by immunohistochemical analysis (red signal) were also GFP+ (green signal) and in combination, appeared as an orange signal; these cells were abundant in host mice receiving WT BM (A–F). Few Mac3+, CD68+, or GFP+ cells were present in host mice receiving CCR2−/− BM (G–L). Confocal image with nuclei identified by DAPI (blue).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2630778&req=5

Figure 2: BM-derived cells define early inflammation after skeletal muscle injury. Representative results were derived from injured skeletal muscle from chimeric mice at 3 or 7 days after CTX; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A–C, G–I) host control groups. D–F, J–L) experimental groups. Most Mac3+ and CD68+ positive cells identified by immunohistochemical analysis (red signal) were also GFP+ (green signal) and in combination, appeared as an orange signal; these cells were abundant in host mice receiving WT BM (A–F). Few Mac3+, CD68+, or GFP+ cells were present in host mice receiving CCR2−/− BM (G–L). Confocal image with nuclei identified by DAPI (blue).
Mentions: In the control, NS-injected muscle of all groups, there were rare foci of skeletal muscle regeneration, a pattern consistent with muscle damage from the needle used for injection. After CTX injury, however, the genotype of the BM donor determined the histological appearance of the muscle; that is, both groups of host mice receiving WT BM had a similar histological appearance, whereas both groups of host mice receiving CCR2−/− BM were comparable. Of importance, there were distinctly different histological patterns, depending on the genotype of the BM donor. Thus, at 3 days after CTX injury, a robust, predominately mononuclear, inflammatory infiltrate was evident within injured muscle in all host mice receiving WT BM (Fig. 1A, D). The majority of these mononuclear cells were of donor BM origin as indicated by the presence of GFP and were strongly positive for multiple macrophage markers, Mac3 and CD68 (Fig. 2A, B, D, E) as well as F4/80 (not shown). The histological patterns were similar using all 3 macrophage markers, and cells positive for macrophage markers were generally also positive for GFP. Although still abundant, cells positive for macrophage markers were decreased at day 7 (Fig. 2C, F) compared with day 3 after CTX injury. Small, regenerated muscle fibers were present at day 7 (Fig. 1B, E). In contrast, host mice receiving CCR2−/− BM exhibited minimal mononuclear cell infiltrates at both day 3 (Fig. 1G, J) and day 7 (Fig. 1H, K) after CTX treatment; consistent with this histological pattern, few GFP+, Mac3+, or CD68+ cells were present at day 3 (Fig. 2G, H, J, K) or day 7 (Fig. 2I, L). At both days 3 and 7 after CTX treatment, the extent of infiltrating cells in mice receiving CCR2−/− BM remained substantially less than that of mice receiving WT BM. In all chimeric groups at 21 days after injury, regenerated fibers were widespread and identified by the presence of centrally located nuclei; however, muscle fiber size appeared to be larger in host mice receiving WT BM (Fig. 1C, F) than in host mice receiving CCR2−/− BM (Fig. 1I, L).

Bottom Line: Limb regeneration requires the coordination of multiple stem cell populations to recapitulate the process of tissue formation.Thus, the expression of CCR2 on BM-derived cells regulated macrophage recruitment into injured muscle, numbers of MPC, and the extent of regenerated myofiber size, all of which were independent of CCR2 expression on host-derived cells.Future studies in regenerative medicine must include consideration of the role of BM-derived cells, possibly macrophages, in CCR2-dependent events that regulate effective skeletal muscle regeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, University of Texas Health Science Center, San Antonio, Texas, USA.

ABSTRACT
Limb regeneration requires the coordination of multiple stem cell populations to recapitulate the process of tissue formation. Therefore, bone marrow (BM) -derived cell regulation of skeletal muscle regeneration was examined in mice lacking the CC chemokine receptor 2 (CCR2). Myofiber size, numbers of myogenic progenitor cells (MPCs), and recruitment of BM-derived cells and macrophages were assessed after cardiotoxin-induced injury of chimeric mice produced by transplanting BM from wild-type (WT) or CCR2(-/-) mice into irradiated WT or CCR2(-/-) host mice. Regardless of the host genotype, muscle regeneration and recruitment of BM-derived cells and macrophages were similar in mice replenished with WT BM, whereas BM-derived cells and macrophage accumulation were decreased and muscle regeneration was impaired in all animals receiving CCR2(-/-) BM. Furthermore, numbers of MPCs (CD34(+)/Sca-1(-)/CD45(-) cells) were significantly increased in mice receiving CCR2(-/-) BM despite the decreased size of regenerated myofibers. Thus, the expression of CCR2 on BM-derived cells regulated macrophage recruitment into injured muscle, numbers of MPC, and the extent of regenerated myofiber size, all of which were independent of CCR2 expression on host-derived cells. Future studies in regenerative medicine must include consideration of the role of BM-derived cells, possibly macrophages, in CCR2-dependent events that regulate effective skeletal muscle regeneration.

Show MeSH
Related in: MedlinePlus