Limits...
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.

Show MeSH

Related in: MedlinePlus

Flow cytometry identification of tissue macrophages/neutrophils and tissue MPCs at 7 days after CTX-induced injury. Representative results were derived from CTX-injured skeletal muscle from chimeric mice; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A) Monocytes/macrophages were defined as CD11b+/Gr-1− cells (left top quadrant) and neutrophils were defined as CD11b+/Gr-1+ cells (right top quadrant). MPCs were defined as CD34+/Sca-1−/CD45− cells. B) Representative histograms in chimeric mice; events contained within the white curve represent cells before addition of antibodies (i.e., contained GFP fluorescence only), whereas events contained within the gray curve were obtained after the addition of CD34, Sca-1, and CD45 antibodies, CD34+ cells gated in R3. C) Dot plot analysis of Sca-1 and CD45 expression on CD34+ cells derived from R3, above. Bottom lower quadrant (Sca-1−/CD45−) represents MPCs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2630778&req=5

Figure 4: Flow cytometry identification of tissue macrophages/neutrophils and tissue MPCs at 7 days after CTX-induced injury. Representative results were derived from CTX-injured skeletal muscle from chimeric mice; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A) Monocytes/macrophages were defined as CD11b+/Gr-1− cells (left top quadrant) and neutrophils were defined as CD11b+/Gr-1+ cells (right top quadrant). MPCs were defined as CD34+/Sca-1−/CD45− cells. B) Representative histograms in chimeric mice; events contained within the white curve represent cells before addition of antibodies (i.e., contained GFP fluorescence only), whereas events contained within the gray curve were obtained after the addition of CD34, Sca-1, and CD45 antibodies, CD34+ cells gated in R3. C) Dot plot analysis of Sca-1 and CD45 expression on CD34+ cells derived from R3, above. Bottom lower quadrant (Sca-1−/CD45−) represents MPCs.

Mentions: Flow cytometry was also used to determine the accumulation of neutrophils (CD11b+/Gr-1+) and macrophages (CD11b+/Gr-1−) in injured muscle after CTX injection (Fig. 4A). Among all chimeric groups, intramuscular neutrophils were increased and were significantly (P≤0.008) higher at day 3 compared with day 7 (Table 4). The BM donor genotype but not the host mouse genotype affected the magnitude of neutrophil recruitment into injured muscle. Thus, at day 3 after CTX, tissue neutrophils in CCR2−/− → CCR2−/− mice were significantly (P=0.05) increased compared with WT → CCR2−/− mice, and at day 7 after CTX, neutrophils were significantly (P≤0.03) higher in host mice that received CCR2−/− BM than in host mice that received WT BM.


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)

Flow cytometry identification of tissue macrophages/neutrophils and tissue MPCs at 7 days after CTX-induced injury. Representative results were derived from CTX-injured skeletal muscle from chimeric mice; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A) Monocytes/macrophages were defined as CD11b+/Gr-1− cells (left top quadrant) and neutrophils were defined as CD11b+/Gr-1+ cells (right top quadrant). MPCs were defined as CD34+/Sca-1−/CD45− cells. B) Representative histograms in chimeric mice; events contained within the white curve represent cells before addition of antibodies (i.e., contained GFP fluorescence only), whereas events contained within the gray curve were obtained after the addition of CD34, Sca-1, and CD45 antibodies, CD34+ cells gated in R3. C) Dot plot analysis of Sca-1 and CD45 expression on CD34+ cells derived from R3, above. Bottom lower quadrant (Sca-1−/CD45−) represents MPCs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Flow cytometry identification of tissue macrophages/neutrophils and tissue MPCs at 7 days after CTX-induced injury. Representative results were derived from CTX-injured skeletal muscle from chimeric mice; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. A) Monocytes/macrophages were defined as CD11b+/Gr-1− cells (left top quadrant) and neutrophils were defined as CD11b+/Gr-1+ cells (right top quadrant). MPCs were defined as CD34+/Sca-1−/CD45− cells. B) Representative histograms in chimeric mice; events contained within the white curve represent cells before addition of antibodies (i.e., contained GFP fluorescence only), whereas events contained within the gray curve were obtained after the addition of CD34, Sca-1, and CD45 antibodies, CD34+ cells gated in R3. C) Dot plot analysis of Sca-1 and CD45 expression on CD34+ cells derived from R3, above. Bottom lower quadrant (Sca-1−/CD45−) represents MPCs.
Mentions: Flow cytometry was also used to determine the accumulation of neutrophils (CD11b+/Gr-1+) and macrophages (CD11b+/Gr-1−) in injured muscle after CTX injection (Fig. 4A). Among all chimeric groups, intramuscular neutrophils were increased and were significantly (P≤0.008) higher at day 3 compared with day 7 (Table 4). The BM donor genotype but not the host mouse genotype affected the magnitude of neutrophil recruitment into injured muscle. Thus, at day 3 after CTX, tissue neutrophils in CCR2−/− → CCR2−/− mice were significantly (P=0.05) increased compared with WT → CCR2−/− mice, and at day 7 after CTX, neutrophils were significantly (P≤0.03) higher in host mice that received CCR2−/− BM than in host mice that received WT BM.

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