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Cited by 119Muscle Physiology and DisordersPluripotent Stem Cells ResearchCongenital heart defects research

The DOI matches its Crossref record; 55 of the 55 references it cites were found in a registry or an index; 3 of the 39 sources its claims cite were checked for support.

In vivo partial reprogramming of myofibers promotes muscle regeneration by remodeling the stem cell niche

Open access
Wang, Chao, Rabadan Ros, Ruben, Martinez-Redondo, Paloma, Ma, Zaijun, Shi, Lei, Xue, Yuan, Guillen-Guillen, Isabel, Huang, Ling, Hishida, Tomoaki, Liao, Hsin-Kai, Nuñez Delicado, Estrella, Rodriguez Esteban, Concepcion, Guillen-Garcia, Pedro, Reddy, Pradeep, Izpisua Belmonte, Juan Carlos·2021·Nature Communications
DOI 10.1038/s41467-021-23353-zPMC PMC8149870
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Abstract

Short-term, systemic expression of the Yamanaka reprogramming factors ( Oct-3/4 , Sox2 , Klf4 and c-Myc [OSKM]) has been shown to rejuvenate aging cells and promote tissue regeneration in vivo. However, the mechanisms by which OSKM promotes tissue regeneration are unknown. In this work, we focus on a specific tissue and demonstrate that local expression of OSKM, specifically in myofibers, induces the activation of muscle stem cells or satellite cells (SCs), which accelerates muscle regeneration in young mice. In contrast, expressing OSKM directly in SCs does not improve muscle regeneration. Mechanistically, expressing OSKM in myofibers regulates the expression of genes important for the SC microenvironment, including upregulation of p21, which in turn downregulates Wnt4 . This is critical because Wnt4 is secreted by myofibers to maintain SC quiescence. Thus, short-term induction of the Yamanaka factors in myofibers may promote tissue regeneration by modifying the stem cell niche.

Overview

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Written from the paper’s full text.

TL;DR

Myofiber-specific, short-term OSKM induction in mice activates satellite cells and accelerates muscle regeneration by inducing p21 and repressing the myofiber-secreted niche factor Wnt4; SC-specific OSKM induction does not improve regeneration. The effect is aging-independent and can be recapitulated by cyclic Wnt4 knockdown.

Key findings

  • Myofiber-specific OSKM induction before injury accelerated regeneration: Cre+ muscles had more eMHC+ myofibers at day 3, more Pax7+ cells, larger regenerated myofibers, more Pax7+MyoD+ myoblasts, and higher hindlimb grip strength at day 6; OSKM induction after injury did not accelerate regeneration.
  • OSKM in myofibers promoted SC activation/proliferation: Cre+ muscles had a 3-fold higher percentage of Pax7+BrdU+ cells; single Cre+ myofibers had 2-fold more Pax7+ cells and 3-fold more activated MyoD+ SCs, with quiescent MyoD− SCs decreased by half. Self-renewal was maintained after serial injuries.
  • SC-specific OSKM induction did not activate/proliferate SCs or improve regeneration; in cultured myoblasts, OSKM inhibited MyoD and miR-133a.
  • Mechanistically, Wnt4 was the only niche-related gene downregulated >2-fold; p21 was upregulated, p21 overexpression increased p21 60-fold and downregulated Wnt4 3-fold, ChIP showed 3-fold enrichment at the Wnt4 TATA-proximal region, and p21 inhibited a Wnt4 reporter 2-fold. Cyclic CasRx Wnt4 knockdown (gRNA1: 85% in vitro, 65% in vivo) recapitulated SC activation and regeneration. In 15-month-old mice, Cre+ muscles had 1.8-fold more Pax7+ cells, 2.8-fold more MyoD+ SCs, and 3-fold more BrdU+ SCs.

Methods

  • Generated myofiber-specific Acta1-Cre/4Fhet and SC-specific Pax7creER/4Fhet inducible OSKM mouse models; used young (6 weeks–4 months) and aging (12–15 months) mice, both male and female. Doxycycline was given in drinking water (1 mg/ml), often cyclically (2 days on/5 days off), with cardiotoxin injury, BrdU labeling, and tamoxifen for Pax7creER induction.
  • Readouts included RNA-seq of EDL/SOL muscles after 2.5 or 8.5 days Dox (DESeq2, WGCNA, GO/GSEA), qPCR, immunostaining/H&E, single myofiber isolation and culture, western blot, ChIP, luciferase assays, and AAV9-CasRx-mediated Wnt4 knockdown.
  • Statistical analysis used two-tailed unpaired Student’s t-test with p<0.05; RNA-seq OSKM/niche comparisons used n=2 biological samples, while many histology experiments used n=4–6 mice.

Limitations

  • Stated: the authors cannot exclude that other cell types (macrophages, endothelial cells, fibroblasts) or ECM/exosome-mediated indirect effects contribute to SC activation; two possible explanations for maintained SC self-renewal (homeostatic mechanism vs. temporary niche modification) were not distinguished.
  • Stated: timing is important—post-injury OSKM did not accelerate regeneration—and systemic vs. myofiber-specific OSKM differ in induction level and p21 induction in SCs.
  • Evident: findings are in mice only; key RNA-seq comparisons for OSKM/niche genes used n=2 biological samples; and although both male and female mice were used, sex-specific effects were not analyzed.

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Crossref · 10.1038/s41467-021-23353-z

Cites

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Figures

Fig. 1 RNA-seq analysis of slow-twitch and fast-twitch muscles with myofiber-specific OSKM induction. a Illustration of the genetic makeup for myofiber-specific OSKM inducible mouse model. For simplicity, Cre+ represents Acta1-Cre+/4Fhet and Cre− represents Acta1-Cre−/4Fhet mice. b Schematic representation of the experimental design. c The fpkm of OSKM in Cre− and Cre+ EDL muscles. n = 2 biological independent samples. d The fpkm of OSKM in Cre− and Cre+ SOL muscles. n = 2 biological independent samples. e Principal component analysis on top 500 most variables genes of Cre− and Cre+ EDL and SOL muscles. f Euclidean distance analysis of the transcriptome of Cre− and Cre+ EDL muscles. g Volcano plots of DE genes in EDL muscles after 2.5- or 8.5-days Dox treatment. h Enriched GO terms in the biological process of commonly changed genes after 2.5- or 8.5-days Dox treatment.
Fig. 1 RNA-seq analysis of slow-twitch and fast-twitch muscles with myofiber-specific OSKM induction. a Illustration of the genetic makeup for myofiber-specific OSKM inducible mouse model. For simplicity, Cre+ represents Acta1-Cre+/4Fhet and Cre− represents Acta1-Cre−/4Fhet mice. b Schematic representation of the experimental design. c The fpkm of OSKM in Cre− and Cre+ EDL muscles. n = 2 biological independent samples. d The fpkm of OSKM in Cre− and Cre+ SOL muscles. n = 2 biological independent samples. e Principal component analysis on top 500 most variables genes of Cre− and Cre+ EDL and SOL muscles. f Euclidean distance analysis of the transcriptome of Cre− and Cre+ EDL muscles. g Volcano plots of DE genes in EDL muscles after 2.5- or 8.5-days Dox treatment. h Enriched GO terms in the biological process of commonly changed genes after 2.5- or 8.5-days Dox treatment.CC BY · PubMed Central
Fig. 2 Myofiber-specific OSKM induction accelerates muscle regeneration. a Relative mRNA levels of OSKM in TA muscles after 2-days Dox treatment (2 days-on) and after 5-days Dox withdrawal (5 days-off). n = 3 Cre− mice for 2 days-on and 5 days-off. n = 3 Cre+ mice for 2 days-on and 4 Cre+ mice for 5 days-off. Error bars represent mean+SD. b Immunostaining of Oct4 and Pax7 in TA muscle sections. Scale bars = 50 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. c, f Schematic representation of the experimental design. d, g Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Error bars represent mean + SD of five biological independent samples. Arrows indicate eMHC+ myofibers in panel d. Scale bars = 50 µm. e Immunostaining of Pax7 and BrdU, and quantification of Pax7 in TA muscle sections. Error bars represent mean + SD of five mice. Representative regions are shown at higher magnification. Scale bars = 50 µm. h H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Error bars represent mean + SD of five mice. Scale bars = 100 µm. i Immunostaining and quantification of Pax7 and MyoD in TA muscle sections. Representative regions are shown at higher magnification. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. Error bars represent mean + SD of five mice. j Hinder limb grip strength at different time points after CTX injection. Error bars represent mean + SD of six mice. A two-sided unpaired Student’s t-test was performed.
Fig. 2 Myofiber-specific OSKM induction accelerates muscle regeneration. a Relative mRNA levels of OSKM in TA muscles after 2-days Dox treatment (2 days-on) and after 5-days Dox withdrawal (5 days-off). n = 3 Cre− mice for 2 days-on and 5 days-off. n = 3 Cre+ mice for 2 days-on and 4 Cre+ mice for 5 days-off. Error bars represent mean+SD. b Immunostaining of Oct4 and Pax7 in TA muscle sections. Scale bars = 50 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. c, f Schematic representation of the experimental design. d, g Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Error bars represent mean + SD of five biological independent samples. Arrows indicate eMHC+ myofibers in panel d. Scale bars = 50 µm. e Immunostaining of Pax7 and BrdU, and quantification of Pax7 in TA muscle sections. Error bars represent mean + SD of five mice. Representative regions are shown at higher magnification. Scale bars = 50 µm. h H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Error bars represent mean + SD of five mice. Scale bars = 100 µm. i Immunostaining and quantification of Pax7 and MyoD in TA muscle sections. Representative regions are shown at higher magnification. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. Error bars represent mean + SD of five mice. j Hinder limb grip strength at different time points after CTX injection. Error bars represent mean + SD of six mice. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central
Fig. 3 Myofiber-specific OSKM induction promotes the activation and proliferation of satellite cells. a Schematic representation of the experimental design. b Immunostaining of Pax7 and BrdU in TA muscle sections. Scale bars = 10 µm. c Quantification of the percentage of SCs with BrdU signals. Error bars represent mean + SD of five mice. d Immunostaining of Pax7 and MyoD in TA muscle sections. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. Representative regions are shown at higher magnification with Scale bars = 10 µm. e Quantification of Pax7+ cells per field. Error bars represent mean + SD of five mice. f Quantification of the percentage of Pax7+MyoD−, Pax7+MyoD+, and Pax7−MyoD+ cells. Error bars represent mean + SD of five mice. g Illustration of the design for myofibers analysis. h Immunostaining of Pax7 and MyoD in single myofibers. Scale bars = 10 µm. i Quantification of Pax7+ cells per myofiber. n = 31 Cre− myofibers and 35 Cre+ myofibers, respectively. Error bars represent mean + SD. j Quantification of the percentage of Pax7+MyoD−, Pax7+MyoD+, and Pax7−MyoD+ cells in single myofibers. Error bars represent mean + SD of four Cre− EDL muscles and 6 Cre+ EDL muscles. k Immunostaining of Pax7 and MyoD in single myofibers after culture for 3 days. Scale bars = 50 µm. l Quantification of cell clusters per myofiber. n = 28 Cre− myofibers and 30 Cre+ myofibers, respectively. Error bars represent mean + SD. m Quantification of Pax7+MyoD+ myoblasts per cluster. n = 76 cell clusters on Cre− myofibers and 128 cell clusters on Cre+ myofibers. Error bars represent mean + SD. A two-sided unpaired Student’s t-test was performed.
Fig. 3 Myofiber-specific OSKM induction promotes the activation and proliferation of satellite cells. a Schematic representation of the experimental design. b Immunostaining of Pax7 and BrdU in TA muscle sections. Scale bars = 10 µm. c Quantification of the percentage of SCs with BrdU signals. Error bars represent mean + SD of five mice. d Immunostaining of Pax7 and MyoD in TA muscle sections. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. Representative regions are shown at higher magnification with Scale bars = 10 µm. e Quantification of Pax7+ cells per field. Error bars represent mean + SD of five mice. f Quantification of the percentage of Pax7+MyoD−, Pax7+MyoD+, and Pax7−MyoD+ cells. Error bars represent mean + SD of five mice. g Illustration of the design for myofibers analysis. h Immunostaining of Pax7 and MyoD in single myofibers. Scale bars = 10 µm. i Quantification of Pax7+ cells per myofiber. n = 31 Cre− myofibers and 35 Cre+ myofibers, respectively. Error bars represent mean + SD. j Quantification of the percentage of Pax7+MyoD−, Pax7+MyoD+, and Pax7−MyoD+ cells in single myofibers. Error bars represent mean + SD of four Cre− EDL muscles and 6 Cre+ EDL muscles. k Immunostaining of Pax7 and MyoD in single myofibers after culture for 3 days. Scale bars = 50 µm. l Quantification of cell clusters per myofiber. n = 28 Cre− myofibers and 30 Cre+ myofibers, respectively. Error bars represent mean + SD. m Quantification of Pax7+MyoD+ myoblasts per cluster. n = 76 cell clusters on Cre− myofibers and 128 cell clusters on Cre+ myofibers. Error bars represent mean + SD. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central
Fig. 4 Analysis of the state and number of SCs 14 and 30 days after CTX injection. a, g Schematic representation of the experimental design. b, h Immunostaining of Pax7 and MyoD in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. White arrows indicate Pax7+MyoD+ myoblasts and Red arrows indicate Pax7+MyoD− SCs. c, i Quantification of Pax7 and the percentage of Pax7+MyoD− SCs in TA muscle sections. d, j Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. e, k Mallory’s trichrome stain of TA muscle sections. Scale bars = 100 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. f, l H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. a–f represents the analysis of SCs 14 days after CTX injection, and g–l represent the analysis of SCs 30 days after CTX injection. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.
Fig. 4 Analysis of the state and number of SCs 14 and 30 days after CTX injection. a, g Schematic representation of the experimental design. b, h Immunostaining of Pax7 and MyoD in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. White arrows indicate Pax7+MyoD+ myoblasts and Red arrows indicate Pax7+MyoD− SCs. c, i Quantification of Pax7 and the percentage of Pax7+MyoD− SCs in TA muscle sections. d, j Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. e, k Mallory’s trichrome stain of TA muscle sections. Scale bars = 100 µm. Similar results were repeated independently in four pairs of mice. In addition, similar results were repeated three times for each mouse. f, l H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. a–f represents the analysis of SCs 14 days after CTX injection, and g–l represent the analysis of SCs 30 days after CTX injection. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central
Fig. 5 OSKM induction does not change the self-renewal of SCs. a Schematic representation of the experimental design for 7 days after triple CTX injury. b Immunostaining of Pax7 and MyoD, and quantification of Pax7 cells in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. White arrows indicate Pax7+ cells. c Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. d H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. e Schematic representation of the experimental design for 30 days after triple CTX injury. f Immunostaining of Pax7, BrdU, and MyoD, and quantification of Pax7 cells and percentage of BrdU+ SCs in TA muscle sections. Scale bars = 25 µm. Red Arrows indicate Pax7+MyoD−BrdU+SCs. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.
Fig. 5 OSKM induction does not change the self-renewal of SCs. a Schematic representation of the experimental design for 7 days after triple CTX injury. b Immunostaining of Pax7 and MyoD, and quantification of Pax7 cells in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. White arrows indicate Pax7+ cells. c Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. d H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. e Schematic representation of the experimental design for 30 days after triple CTX injury. f Immunostaining of Pax7, BrdU, and MyoD, and quantification of Pax7 cells and percentage of BrdU+ SCs in TA muscle sections. Scale bars = 25 µm. Red Arrows indicate Pax7+MyoD−BrdU+SCs. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central
Fig. 6 OSKM induction represses the expression of Wnt4 through p21. a Heatmap shows the fold change of SCs niche-related genes in Cre+ EDL muscles compared to Cre− EDL muscles. b The fpkm of Wnt4 and p21 in Cre− and Cre+ EDL muscles. n = 2 independent biological samples. c Relative mRNA levels of Wnt4 and p21 in TA muscles after 2-days Dox treatment (2 days-on) and after 5-days Dox withdrawal (5 days-off). n = 4 Cre- mice for 2 days-on and 3 Cre− mice for 5 days-off. n = 5 Cre+ mice for 2 days-on and Cre+ mice for 5 days-off. Error bars represent mean + SD. d Relative mRNA levels of OSKM in single myofibers after 2-days Dox treatment. Error bars represent mean + SD of four independent biological samples. e Relative mRNA levels of p21 and Wnt4 in single myofibers after 2-days Dox treatment. Error bars represent mean + SD of four independent biological samples. f Western blots detection and quantification of the protein levels of p53 and p21 in TA muscles of Cre− and Cre+ mice. Gapdh is the internal control. Error bars represent mean + SD of Cre− 6 mice and 5 Cre+ mice. g Relative mRNA levels of p21 and Wnt4 in TA muscles with CAG-3xFLAG-p21 or CAG-Td plasmids. Error bars represent mean + SD of four mice. h Enrichments of the TATA-proximal region of the Wnt4 promoter by 3xFLAG-p21 as determined by ChIP assay using an antibody against FLAG. Error bars represent mean + SD of four independent biological samples. i Luciferase assay with a reporter containing the TATA-proximal region upstream of the minimal CMV promoter (Pmin). Error bars represent mean + SD of four independent biological samples. j Hypothetical model showing how OSKM regulates Wnt4. A two-sided unpaired Student’s t-test was performed.
Fig. 6 OSKM induction represses the expression of Wnt4 through p21. a Heatmap shows the fold change of SCs niche-related genes in Cre+ EDL muscles compared to Cre− EDL muscles. b The fpkm of Wnt4 and p21 in Cre− and Cre+ EDL muscles. n = 2 independent biological samples. c Relative mRNA levels of Wnt4 and p21 in TA muscles after 2-days Dox treatment (2 days-on) and after 5-days Dox withdrawal (5 days-off). n = 4 Cre- mice for 2 days-on and 3 Cre− mice for 5 days-off. n = 5 Cre+ mice for 2 days-on and Cre+ mice for 5 days-off. Error bars represent mean + SD. d Relative mRNA levels of OSKM in single myofibers after 2-days Dox treatment. Error bars represent mean + SD of four independent biological samples. e Relative mRNA levels of p21 and Wnt4 in single myofibers after 2-days Dox treatment. Error bars represent mean + SD of four independent biological samples. f Western blots detection and quantification of the protein levels of p53 and p21 in TA muscles of Cre− and Cre+ mice. Gapdh is the internal control. Error bars represent mean + SD of Cre− 6 mice and 5 Cre+ mice. g Relative mRNA levels of p21 and Wnt4 in TA muscles with CAG-3xFLAG-p21 or CAG-Td plasmids. Error bars represent mean + SD of four mice. h Enrichments of the TATA-proximal region of the Wnt4 promoter by 3xFLAG-p21 as determined by ChIP assay using an antibody against FLAG. Error bars represent mean + SD of four independent biological samples. i Luciferase assay with a reporter containing the TATA-proximal region upstream of the minimal CMV promoter (Pmin). Error bars represent mean + SD of four independent biological samples. j Hypothetical model showing how OSKM regulates Wnt4. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central
Fig. 7 CasRx-mediated cyclic Wnt4 knockdown accelerates muscle regeneration. a AAV-gRNA1-CasRx vector. b Relative mRNA levels of Wnt4 in AAV-gRNA1-CasRx (KD)- or AAV-CasRx (Control)-treated TA muscles after 2-days Dox treatment and after 5-days Dox withdrawal. c Schematic representation of the experimental design. d Immunostaining of Pax7 and BrdU and quantification of the percentage of Pax7+BrdU+ cells in TA muscle sections. Scale bars = 10 µm. e Immunostaining of Pax7 and MyoD and quantification of Pax7+ cells per field and the percentage of Pax7+MyoD+ cells in TA muscle sections. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. f Schematic representation of the experimental design. g Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. h Immunostaining of Pax7 and MyoD, and quantification of Pax7+MyoD− SCs and Pax7+MyoD+myoblasts in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. Arrows indicate Pax7+ cells. i H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.
Fig. 7 CasRx-mediated cyclic Wnt4 knockdown accelerates muscle regeneration. a AAV-gRNA1-CasRx vector. b Relative mRNA levels of Wnt4 in AAV-gRNA1-CasRx (KD)- or AAV-CasRx (Control)-treated TA muscles after 2-days Dox treatment and after 5-days Dox withdrawal. c Schematic representation of the experimental design. d Immunostaining of Pax7 and BrdU and quantification of the percentage of Pax7+BrdU+ cells in TA muscle sections. Scale bars = 10 µm. e Immunostaining of Pax7 and MyoD and quantification of Pax7+ cells per field and the percentage of Pax7+MyoD+ cells in TA muscle sections. Pax7+ cells are indicated by arrows. Scale bars = 50 µm. f Schematic representation of the experimental design. g Immunostaining of embryonic myosin heavy chain (eMHC) and Dystrophin in TA muscle sections, and the quantification of the percentage of immature myofibers that express eMHC. Scale bars = 50 µm. h Immunostaining of Pax7 and MyoD, and quantification of Pax7+MyoD− SCs and Pax7+MyoD+myoblasts in TA muscle sections. Scale bars = 50 µm. Representative regions are shown at higher magnification. Scale bars = 25 µm. Arrows indicate Pax7+ cells. i H&E staining of TA muscle sections and myofiber size distributions in TA muscle sections. Scale bars = 100 µm. Error bars represent mean + SD of four mice. A two-sided unpaired Student’s t-test was performed.CC BY · PubMed Central

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  • Probably not a substantial claim. 16
  • It may state two separate claims as one. 35
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49 of 49

  • The paper relies on this without support.

    Young mice lack aging-related decline, so any OSKM-induced improvement in muscle regeneration in them cannot be attributed to rejuvenation of aged cells.

    “In addition, we chose young mice to investigate whether the improvement of regeneration can be achieved by OSKM induction regardless of its rejuvenating effect.”

  • The paper relies on this without support.

    The aging process is much slower in WT mice compared to progeria mice.

    “The aging process is much slower in WT mice compared to progeria mice and longer time may be required to observe the effect of OSKM on SC number in naturally aging mice.”

  • The paper relies on this without support.

    The intrinsic regulatory machinery is efficient in young SCs.

    “The intrinsic regulatory machinery is efficient in young SCs, therefore, further improvement of SC quality is limited.”

  • The paper relies on this without support.

    SC activation is required for muscle regeneration.

    “SCs activation is required for muscle regeneration, but the activation kinetics is delayed in aged SCs30.”
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Authors
Wang, C., Rabadan Ros, R., Martinez-Redondo, P., Ma, Z., Shi, L., Xue, Y., Guillen-Guillen, I., Huang, L., Hishida, T., Liao, H.-K., Nuñez Delicado, E., Rodriguez Esteban, C., Guillen-Garcia, P., Reddy, P., & Izpisua Belmonte, J. C.
Affiliations
Salk Institute for Biological Studies (US)
ORCID
Venue
Nature Communications
Publisher
Springer Science and Business Media LLC
Published
2021-05-25
Volume
12
Issue
1
Pages
3094-3094
ISSN
2041-1723 (ISSN-L)
DOI
10.1038/s41467-021-23353-z
PMC
PMC8149870
OpenAlex
W3165546848
Cited by
119
References
55
Citations by year
2026: 16 · 2025: 24 · 2024: 27 · 2023: 28 · 2022: 17 · 2021: 7
FWCI
6.19
Type
journal article
Language
en
Open access
Licence
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
This work was supported by Asociación de Futbolistas Españoles (AFE), Fundacion Pedro Guillen, Universidad Católica San Antonio de Murcia (UCAM), The Glenn Foundation, The Moxie Foundation and CIRM
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Pluripotent Stem Cells Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Congenital heart defects research
Keywords
partial reprogramming, Yamanaka factors, OSKM, muscle regeneration, satellite cells, muscle stem cells, stem cell niche, muscle fibers, Wnt4, p21, stem cell quiescence, aging cells, local gene expression
MeSH terms
Kruppel-Like Factor 4, Animals, Cell Differentiation, Cells, Cultured, Female, Mice, Transgenic, Myofibrils, Regeneration, Gene Expression, Proto-Oncogene Proteins c-myc, Satellite Cells, Skeletal Muscle, Octamer Transcription Factor-3, Kruppel-Like Transcription Factors, Stem Cell Niche, SOXB1 Transcription Factors, Wnt4 Protein, Cellular Reprogramming

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