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Cardiomyocyte proliferation and progenitor cell recruitment underlie therapeutic regeneration after myocardial infarction in the adult mouse heart.

Malliaras K, Zhang Y, Seinfeld J, Galang G, Tseliou E, Cheng K, Sun B, Aminzadeh M, Marbán E - EMBO Mol Med (2013)

Bottom Line: After MI, new cardiomyocytes arise from both progenitors as well as pre-existing cardiomyocytes.Transplantation of CDCs upregulates host cardiomyocyte cycling and recruitment of endogenous progenitors, while boosting heart function and increasing viable myocardium.The observed phenomena cannot be explained by cardiomyocyte polyploidization, bi/multinucleation, cell fusion or DNA repair.

View Article: PubMed Central - PubMed

Affiliation: Cedars-Sinai Heart Institute, Los Angeles, CA, USA.

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Related in: MedlinePlus

Origins of postnatal cardiomyogenesis in the adult mouse heart by flow cytometryA. FACS-sorted GFP+ and GFP− cardiomyocytes were subsequently stained for αSA. Only αSA+ cells were examined.B, C. Flow cytometric analysis of GFP+/αSA+ and GFP−/αSA+ cardiomyocytes for BrdU incorporation reveals that, in the normal mouse heart, cardiomyocyte turnover occurs exclusively through proliferation of adult cardiomyocytes. After MI, cardiomyocyte proliferation is upregulated, while progenitor cells also contribute to the replacement of lost cardiomyocytes. CDCs amplify both stem cell-mediated myocyte replenishment and adult cardiomyocyte proliferation. Numbers in flow cytometry plots indicate averages for groups. Red dots indicate BrdU+ while black dots indicate BrdU− cardiomyocytes (colour gating has been applied to the images). (*p < 0.05 compared to GFP+ cardiomyocytes; #p < 0.05 compared to MI and sham; ∧p < 0.05 to sham; n = 5/group). All error bars represent SDs. One-way ANOVA followed by LSD post hoc test and independent samples t-test were used for statistical analysis (GFP+: MI vs sham: p = 0.01, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP−: MI vs sham: p < 0.001, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP+vs GFP− MI p < 0.001, GFP+vs GFP− CDCs p < 0.001; all other p = ns).
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fig07: Origins of postnatal cardiomyogenesis in the adult mouse heart by flow cytometryA. FACS-sorted GFP+ and GFP− cardiomyocytes were subsequently stained for αSA. Only αSA+ cells were examined.B, C. Flow cytometric analysis of GFP+/αSA+ and GFP−/αSA+ cardiomyocytes for BrdU incorporation reveals that, in the normal mouse heart, cardiomyocyte turnover occurs exclusively through proliferation of adult cardiomyocytes. After MI, cardiomyocyte proliferation is upregulated, while progenitor cells also contribute to the replacement of lost cardiomyocytes. CDCs amplify both stem cell-mediated myocyte replenishment and adult cardiomyocyte proliferation. Numbers in flow cytometry plots indicate averages for groups. Red dots indicate BrdU+ while black dots indicate BrdU− cardiomyocytes (colour gating has been applied to the images). (*p < 0.05 compared to GFP+ cardiomyocytes; #p < 0.05 compared to MI and sham; ∧p < 0.05 to sham; n = 5/group). All error bars represent SDs. One-way ANOVA followed by LSD post hoc test and independent samples t-test were used for statistical analysis (GFP+: MI vs sham: p = 0.01, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP−: MI vs sham: p < 0.001, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP+vs GFP− MI p < 0.001, GFP+vs GFP− CDCs p < 0.001; all other p = ns).

Mentions: We next sought to determine the relative contributions of adult cardiomyocyte proliferation and cardiomyogenic differentiation of endogenous stem cells in postnatal cardiomyogenesis. 4-OH-Tamoxifen-pulsed 6–8 week-old bitransgenic mice were randomized to undergo: (a) sham surgery; (b) induction of MI by permanent LAD ligation; or (c) induction of MI followed by intramyocardial injection of mouse CDCs (2 × 105, grown from wild-type animals) into the infarct border zone. Mice were subsequently pulsed with daily BrdU injections for 5 weeks, at which point hearts were explanted and enzymatically dissociated. We used FACS-sorting (gating on large cells) to isolate GFP+ and GFP− cardiomyocytes (Fig 7A), which subsequently underwent flow cytometry for αSA expression and BrdU incorporation. Only αSA+ cells were examined (Fig 7A), in order to assure the purity of the GFP− fraction, and to avoid confounding results arising from contamination by GFP− non-myocytes. By comparing the rates of BrdU incorporation in GFP+ versus GFP− cardiomyocytes, we were able to calculate the absolute rates and relative magnitudes of induced secondary cardiomyocyte proliferation and cardiomyogenic differentiation of recruited endogenous stem cells in postnatal cardiomyogenesis in the normal, infarcted and CDC-treated hearts. Taking into account that GFP only marks preformed resident cardiomyocytes, equal rates of BrdU incorporation in GFP+ and GFP− myocytes would translate to no significant contribution of endogenous progenitors to the myocyte pool during the course of BrdU pulsing (as the cardiomyocytes arising from progenitors would by default be GFP−). Increased rates of BrdU incorporation in the GFP− myocyte fraction would translate to myogenic differentiation of progenitors during the course of BrdU pulsing.


Cardiomyocyte proliferation and progenitor cell recruitment underlie therapeutic regeneration after myocardial infarction in the adult mouse heart.

Malliaras K, Zhang Y, Seinfeld J, Galang G, Tseliou E, Cheng K, Sun B, Aminzadeh M, Marbán E - EMBO Mol Med (2013)

Origins of postnatal cardiomyogenesis in the adult mouse heart by flow cytometryA. FACS-sorted GFP+ and GFP− cardiomyocytes were subsequently stained for αSA. Only αSA+ cells were examined.B, C. Flow cytometric analysis of GFP+/αSA+ and GFP−/αSA+ cardiomyocytes for BrdU incorporation reveals that, in the normal mouse heart, cardiomyocyte turnover occurs exclusively through proliferation of adult cardiomyocytes. After MI, cardiomyocyte proliferation is upregulated, while progenitor cells also contribute to the replacement of lost cardiomyocytes. CDCs amplify both stem cell-mediated myocyte replenishment and adult cardiomyocyte proliferation. Numbers in flow cytometry plots indicate averages for groups. Red dots indicate BrdU+ while black dots indicate BrdU− cardiomyocytes (colour gating has been applied to the images). (*p < 0.05 compared to GFP+ cardiomyocytes; #p < 0.05 compared to MI and sham; ∧p < 0.05 to sham; n = 5/group). All error bars represent SDs. One-way ANOVA followed by LSD post hoc test and independent samples t-test were used for statistical analysis (GFP+: MI vs sham: p = 0.01, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP−: MI vs sham: p < 0.001, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP+vs GFP− MI p < 0.001, GFP+vs GFP− CDCs p < 0.001; all other p = ns).
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fig07: Origins of postnatal cardiomyogenesis in the adult mouse heart by flow cytometryA. FACS-sorted GFP+ and GFP− cardiomyocytes were subsequently stained for αSA. Only αSA+ cells were examined.B, C. Flow cytometric analysis of GFP+/αSA+ and GFP−/αSA+ cardiomyocytes for BrdU incorporation reveals that, in the normal mouse heart, cardiomyocyte turnover occurs exclusively through proliferation of adult cardiomyocytes. After MI, cardiomyocyte proliferation is upregulated, while progenitor cells also contribute to the replacement of lost cardiomyocytes. CDCs amplify both stem cell-mediated myocyte replenishment and adult cardiomyocyte proliferation. Numbers in flow cytometry plots indicate averages for groups. Red dots indicate BrdU+ while black dots indicate BrdU− cardiomyocytes (colour gating has been applied to the images). (*p < 0.05 compared to GFP+ cardiomyocytes; #p < 0.05 compared to MI and sham; ∧p < 0.05 to sham; n = 5/group). All error bars represent SDs. One-way ANOVA followed by LSD post hoc test and independent samples t-test were used for statistical analysis (GFP+: MI vs sham: p = 0.01, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP−: MI vs sham: p < 0.001, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP+vs GFP− MI p < 0.001, GFP+vs GFP− CDCs p < 0.001; all other p = ns).
Mentions: We next sought to determine the relative contributions of adult cardiomyocyte proliferation and cardiomyogenic differentiation of endogenous stem cells in postnatal cardiomyogenesis. 4-OH-Tamoxifen-pulsed 6–8 week-old bitransgenic mice were randomized to undergo: (a) sham surgery; (b) induction of MI by permanent LAD ligation; or (c) induction of MI followed by intramyocardial injection of mouse CDCs (2 × 105, grown from wild-type animals) into the infarct border zone. Mice were subsequently pulsed with daily BrdU injections for 5 weeks, at which point hearts were explanted and enzymatically dissociated. We used FACS-sorting (gating on large cells) to isolate GFP+ and GFP− cardiomyocytes (Fig 7A), which subsequently underwent flow cytometry for αSA expression and BrdU incorporation. Only αSA+ cells were examined (Fig 7A), in order to assure the purity of the GFP− fraction, and to avoid confounding results arising from contamination by GFP− non-myocytes. By comparing the rates of BrdU incorporation in GFP+ versus GFP− cardiomyocytes, we were able to calculate the absolute rates and relative magnitudes of induced secondary cardiomyocyte proliferation and cardiomyogenic differentiation of recruited endogenous stem cells in postnatal cardiomyogenesis in the normal, infarcted and CDC-treated hearts. Taking into account that GFP only marks preformed resident cardiomyocytes, equal rates of BrdU incorporation in GFP+ and GFP− myocytes would translate to no significant contribution of endogenous progenitors to the myocyte pool during the course of BrdU pulsing (as the cardiomyocytes arising from progenitors would by default be GFP−). Increased rates of BrdU incorporation in the GFP− myocyte fraction would translate to myogenic differentiation of progenitors during the course of BrdU pulsing.

Bottom Line: After MI, new cardiomyocytes arise from both progenitors as well as pre-existing cardiomyocytes.Transplantation of CDCs upregulates host cardiomyocyte cycling and recruitment of endogenous progenitors, while boosting heart function and increasing viable myocardium.The observed phenomena cannot be explained by cardiomyocyte polyploidization, bi/multinucleation, cell fusion or DNA repair.

View Article: PubMed Central - PubMed

Affiliation: Cedars-Sinai Heart Institute, Los Angeles, CA, USA.

Show MeSH
Related in: MedlinePlus