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Cited by 662Tissue Engineering and Regenerative Medicine3D Printing in Biomedical ResearchHydrogels: synthesis, properties, applications

Proangiogenic scaffolds as functional templates for cardiac tissue engineering

Open access
Madden, Lauran R., Mortisen, Derek J., Sussman, Eric M., Dupras, Sarah K., Fugate, James A., Cuy, Janet L., Hauch, Kip D., Laflamme, Michael A. +2 more·2010·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.1006442107PMC PMC2930533
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Abstract

We demonstrate here a cardiac tissue-engineering strategy addressing multicellular organization, integration into host myocardium, and directional cues to reconstruct the functional architecture of heart muscle. Microtemplating is used to shape poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogel into a tissue-engineering scaffold with architectures driving heart tissue integration. The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring. Surface-modified scaffolds were seeded with human ES cell-derived cardiomyocytes and cultured in vitro. Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities. Cardiac implantation of acellular scaffolds with pore diameters of 30–40 μm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state. This work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response.

AI snapshot

Written from the paper’s full text.

TL;DR

A microtemplated pHEMA-co-MAA hydrogel scaffold with parallel channels and interconnected spherical pores was developed to organize cardiomyocytes and promote vascularization in cardiac tissue engineering. In vitro, hESC-derived cardiomyocytes survived at adult-heart-like densities, and acellular myocardial implants with 30–40 μm pores showed angiogenesis, reduced fibrosis, and a macrophage shift toward M2 markers.

Key findings

  • The bimodal scaffold had 60-μm channels occupying 25% of scaffold volume, with the remaining 75% as a porous network of ∼60% void space; channel spacing was 60 μm and pores ranged from 20–40 μm.
  • hESC-derived cardiomyocytes became ∼95% β-myosin heavy chain–positive after 5-d serum-free culture, reached 42 ± 10 × 10⁶/cm³ within channels versus 20 × 10⁶/cm³ in adult human heart, remained viable up to 300 μm from the scaffold edge under static culture, and proliferated for at least 2 wk.
  • In acellular rat myocardial implants, collagen capsule thickness followed 20 μm ≈ 30 μm < 60 μm ≈ solid in nude rats; perfused vessel density was significantly higher with 40- and 80-μm pores.
  • Macrophage phenotype shifted with porous architecture: NOS2+/MMR+ macrophages were greater for all porous implants (P < 0.05 versus nonporous), and NOS2−/MMR+ cells were <20% of CD68+ cells and tended to be most common in highly vascular 40-μm scaffolds (P = 0.06 versus nonporous).

Methods

  • Bimodal pHEMA-co-MAA hydrogel scaffolds were fabricated by polymer fiber templating and microsphere templating, then surface-derivatized with rat tail collagen I using EDC/NHS chemistry.
  • Scaffolds were seeded with primary chicken embryonic cardiomyocytes (∼20–25% cardiomyocytes) or hESC-derived cardiomyocytes; 2-mm-thick gels were punched with a 3-mm biopsy punch, loaded with 5 million cells in 50 μL, centrifuged for 5 min at ∼200 × g three times, and cultured in vitro.
  • Acellular collagen-modified scaffolds of varying pore size were implanted into myocardium of athymic nude and immunocompetent Sprague-Dawley rats for 4 wk; analysis included H&E, trichrome, immunohistochemistry, biotinylated lectin perfusion, and quantification with means ± 95% confidence intervals, paired t test, and n = 3 or 4.

Limitations

  • The paper states that myocardial response to pores >80 μm was not determined because of the small size of the rat heart, and that future studies will examine additional macrophage activation markers and cytokine expression to determine where scaffold-associated macrophages lie on the polarization continuum and how they direct neovascularization.
  • The paper states that hESC-derived cardiomyocytes did not fully assemble sarcomeres, and future studies will evaluate mechanical stimulation for maturation and sarcomeric organization.
  • Evident from the text: in vivo implantation tested only acellular scaffolds, not cell-seeded constructs; chick cardiomyocyte constructs were limited to 1 wk because nonmyocyte overgrowth choked off oxygen and nutrients.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1073/pnas.1006442107

Cites

39 of 39 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 28 cited sources checked · 0 supported · 0 flagged

  • Findingown data
    § Results

    hESC-CM density was 42 ± 10 × 10^6/cm3.

    “Although limited to the channels (25% construct volume), hESC-CM density (42 ± 10 × 106/cm3) compared favorably with cardiomyocyte density in adult human heart (20 × 106/cm3) (15).”
    Quote in the paperSubstantial claim
  • Findingreasoning
    § Results

    Nonmyocyte proliferation choked off oxygen and nutrients to cardiomyocytes, limiting their viability to within ∼150 μm of the construct surface.

    “Nonmyocyte proliferation choked off oxygen and nutrients to cardiomyocytes, limiting their viability to within ∼150 μm of the construct surface.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Results

    The elastic modulus of porous constructs is 12 ± 6 kPa.

    “Here, the elastic modulus of the solid polymer (155 ± 14 kPa) is similar to that of rat myocardium (590 ± 22 kPa) (14), whereas porous constructs (12 ± 6 kPa) are one order of magnitude lower than myocardial tissue and two orders of magnitude below myocardial scar tissue (4,700 ± 1,400 kPa) (14).”
    Quote in the paperSubstantial claim
  • Findingnone given
    § Results

    Fabricated constructs resembled the structure and hierarchical organization of native myocardium.

    “Fabricated constructs resembled the structure and hierarchical organization of native myocardium.”
    Quote in the paperNot a substantial claim
  • Findingown data
    § Results

    Scaffolds initially seeded with primary chicken embryonic-derived cardiomyocytes (~20-25% cardiomyocytes) could be seeded at high cell densities.

    “Scaffolds initially were seeded with primary chicken embryonic-derived cardiomyocytes (∼20–25% cardiomyocytes). This model showed we could seed constructs at high cell densities (Fig. 1 C and D).”
    Quote in the paperSubstantial claim
  • May combine two claims. 35
  • Classified as probably not a substantial claim. 5

  • May combine two claims.

    Findingown data
    § Results

    In every experiment, nonmyocytes declined over 5-d culture in serum-free medium, resulting in predominantly cardiomyocytes (~95% β-myosin heavy chain-positive) organized within scaffold channels.

    “In every experiment, nonmyocytes declined over 5-d culture in serum-free medium, resulting in predominantly cardiomyocytes (∼95% β-myosin heavy chain–positive) organized within scaffold channels.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Results

    In the chosen configuration, channels account for 25% of scaffold volume; the remaining 75% is a porous network of ∼60% void space.

    “In this configuration (Fig. 1 A and B), channels account for 25% of scaffold volume; the remaining 75% is a porous network of ∼60% void space.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Abstract

    Cardiac implantation of acellular scaffolds with pore diameters of 30-40 μm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state.

    “Cardiac implantation of acellular scaffolds with pore diameters of 30–40 μm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Results

    Cardiomyocytes expressed the contractile proteins β-myosin heavy chain and troponin T.

    “Cardiomyocytes expressed the contractile proteins β-myosin heavy chain (Fig. 1F) and troponin T (Fig. 1G).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § Abstract

    A bimodal scaffold architecture provides parallel channels to develop cardiomyocyte muscle bundles in vitro and a surrounding sphere-templated, interconnected porous network for improved mass transfer to generate larger tissue constructs.

    “In this study, a bimodal scaffold architecture provides parallel channels to develop cardiomyocyte muscle bundles in vitro and also to develop a surrounding sphere-templated, interconnected porous network for improved mass transfer to generate larger tissue constructs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Abstract

    Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities.

    “Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Results

    Immunostaining against sarcomeric myosin showed that cardiomyocytes predominantly occupied the channels, whereas nonmyocytes migrated into the porous network and scaffold edge.

    “Immunostaining against sarcomeric myosin, a striated muscle marker, showed that cardiomyocytes predominantly occupied the channels (Fig. 1E), whereas nonmyocytes migrated into the porous network and scaffold edge.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Abstract

    The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring.

    “The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given
    § Abstract

    Implantation studies show that acellular, sphere-templated, porous constructs are able to direct rapid angiogenesis and minimize fibrosis in heart muscle.

    “Implantation studies show that acellular, sphere-templated, porous constructs are able to direct rapid angiogenesis and minimize fibrosis in heart muscle.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Results

    These embryonic-stage cardiomyocytes did not fully assemble sarcomeres but still contracted with sufficient force to deform the polymer scaffold.

    “These embryonic-stage cardiomyocytes did not fully assemble sarcomeres but still contracted with sufficient force to deform the polymer scaffold (Movie S1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Results

    H&E stain shows the construct bordered by a thin, fibrous capsule, whereas the pores and surrounding interface are filled with granulation tissue.

    “H&E stain shows the construct bordered by a thin, fibrous capsule, whereas the pores and surrounding interface are filled with granulation tissue (Fig. 2 A and B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Results

    A majority of MΦ at implant sites were NOS2+/MMR+ or NOS2+/MMR−; NOS2−/MMR+ cells comprised <20% of all CD68+ cells and tended to be most common in the highly vascular 40-μm scaffolds (P = 0.06 versus nonporous).

    “A majority of MΦ at implant sites were NOS2+/MMR+ or NOS2+/MMR−; NOS2−/MMR+ cells comprised <20% of all CD68+ cells and tended to be most common in the highly vascular 40-μm scaffolds (P = 0.06 versus nonporous).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Discussion

    A majority of the activated MΦ expressed NOS2, indicating the biomaterial activates proinflammatory pathways.

    “A majority of the activated MΦ expressed NOS2, indicating the biomaterial activates proinflammatory pathways.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Results

    Although MΦ dominated the construct surface, the spherical pores appeared to inhibit foreign body giant cell formation.

    “Although MΦ dominated the construct surface, the spherical pores appeared to inhibit foreign body giant cell formation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Discussion

    Cardiac implantation of acellular constructs verified the feasibility of using bimodal pHEMA-co-MAA scaffolds for in vivo cell delivery and established a size threshold necessary for vessel lumen formation and perfusion.

    “Cardiac implantation of acellular constructs verified the feasibility of using bimodal pHEMA-co-MAA scaffolds for in vivo cell delivery and established a size threshold necessary for vessel lumen formation and perfusion.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Discussion

    MMR expression increased significantly at porous implants, and this increase tracked with improved neovascularization for implants with pores >20 μm.

    “MMR expression increased significantly at porous implants, and this increase tracked with improved neovascularization for implants with pores >20 μm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § Discussion

    In acellular cardiac implants, the sphere-templated architecture maximized neovascularization while minimizing fibrosis.

    “In acellular cardiac implants, the sphere-templated architecture maximized neovascularization while minimizing fibrosis.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Discussion

    For a mixed cell population of 20-25% cardiomyocytes, the less-migratory cardiomyocytes principally remained in channels, whereas noncardiomyocytes migrated throughout the porous network.

    “For this mixed cell population of 20–25% cardiomyocytes, the less-migratory cardiomyocytes principally remained in channels, whereas noncardiomyocytes migrated throughout the porous network.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § Results

    Constructs with a 30- to 40-μm pore size achieve maximal vascularization and minimal fibrous encapsulation.

    “Thus, we demonstrate that constructs with a 30- to 40-μm pore size achieve maximal vascularization and minimal fibrous encapsulation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation
    § Discussion

    Density of functional vessels within implants with pore sizes of 40 and 80 μm was similar to previous reports of prevascularized cardiac implants without complications of tricell sourcing and seeding.

    “The density of functional vessels within implants with pore sizes of 40 and 80 μm was similar to previous reports of prevascularized cardiac implants (30) without complications of tricell (cardiomyocyte, endothelial cell, fibroblast) sourcing and seeding.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30] Lesman A, et al. Transplantation of a tissue-engineered human vascularized cardiac muscle. Tissue Eng Part A. 2010;16:115–125. doi: 10.1089/ten.TEA.2009.0130. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

  • May combine two claims.

    Findingown data
    § Results

    Collagen capsule thickness correlated with pore size, so that 20 μm ≈ 30 μm < 60 μm ≈ solid in the nude rat.

    “Collagen capsule thickness correlated with pore size, so that 20 μm ≈ 30 μm < 60 μm ≈ solid in the nude rat (Fig. 2J).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data
    § Results

    Construct cardiomyocyte density may increase over time, because hESC-CM maintain their proliferative capacity for at least 2 wk in culture.

    “Construct cardiomyocyte density may increase over time, because hESC-CM maintain their proliferative capacity for at least 2 wk in culture (Fig. S1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § Results

    Tuning the scaffold modulus below that of myocardium would facilitate mechanical stimulation of engrafted cells in vivo while minimizing diastolic dysfunction associated with stiff infarct scar tissue.

    “We reasoned that tuning the scaffold modulus below that of myocardium would facilitate mechanical stimulation of engrafted cells in vivo while minimizing diastolic dysfunction associated with stiff infarct scar tissue.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § Results

    Fibrous encapsulation and vascularization are sensitive to pore size for s.c. implants in mice.

    “Previously, our group showed that fibrous encapsulation and vascularization are sensitive to pore size for s.c. implants in mice (10).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [10] Marshall AJ, et al. Biomaterials with tightly controlled pore size that promote vascular in-growth. Polymer Preprints. 2004;45:100–101. [Google Scholar]

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § Abstract

    A scaffold can promote survival and integration by enhancing neovascularization while minimizing fibrotic encapsulation.

    “A scaffold can also promote survival and integration by enhancing neovascularization while minimizing fibrotic encapsulation (10).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [10] Marshall AJ, et al. Biomaterials with tightly controlled pore size that promote vascular in-growth. Polymer Preprints. 2004;45:100–101. [Google Scholar]

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data
    § Abstract

    The work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response.

    “This work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Abstract

    Studies show that 50-90% of injected cells are lost by extrusion and that ∼90% of remaining cells die within 1 wk of implantation.

    “Studies show that 50–90% of injected cells are lost by extrusion (1) and that ∼90% of remaining cells die within 1 wk of implantation (2).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [1] Müller-Ehmsen J, et al. Survival and development of neonatal rat cardiomyocytes transplanted into adult myocardium. J Mol Cell Cardiol. 2002;34:107–116. doi: 10.1006/jmcc.2001.1491. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [2] Zhang M, et al. Cardiomyocyte grafting for cardiac repair: Graft cell death and anti-death strategies. J Mol Cell Cardiol. 2001;33:907–921. doi: 10.1006/jmcc.2001.1367. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning
    § Results

    Porous channel walls were free of cells and available for mass transfer.

    “Thus, porous channel walls were free of cells and available for mass transfer (Fig. 1F).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning
    § Discussion

    Myocardial response to larger pores (>80 μm) was not determined because of the small size of the rat heart.

    “Constrained by the small size of the rat heart, myocardial response to larger pores (>80 μm) was not determined.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data
    § Results

    Because most endothelial structures were perfused with the lectin, and maturation of vessels was evident, these findings suggest functional neovascularization.

    “Because most endothelial structures were perfused with the lectin, and maturation of vessels was evident, these findings suggest functional neovascularization.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § Discussion

    This die-off resulted in interstices free of cells for improved mass transfer and cell survival up to 300 μm into the scaffold.

    “This die-off resulted in interstices free of cells for improved mass transfer and cell survival up to 300 μm into the scaffold.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Discussion

    These earlier studies used materials with broad pore-size distributions (only average pore size was reported), making conclusions about the effects of pore size difficult.

    “These earlier studies used materials with broad pore-size distributions (only average pore size was reported), making conclusions about the effects of pore size difficult.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [31] White R, et al. Effect of healing on small internal diameter arterial graft compliance. Biomater Med Devices Artif Organs. 1983;11:21–29. doi: 10.3109/10731198309118791. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [32] Beahan P, Hull D. A study of the interface between a fibrous polyurethane arterial prosthesis and natural tissue. J Biomed Mater Res. 1982;16:827–838. doi: 10.1002/jbm.820160608. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data
    § Discussion

    The increase in MMR expression resulted in a large fraction of MΦ of a mixed phenotype at porous implants, showing that a defined porous architecture turns on supposed prohealing pathways in these NOS2+ MΦ.

    “The increase in MMR expression resulted in a large fraction of MΦ of a mixed phenotype at porous implants, showing that a defined porous architecture turns on supposed prohealing pathways in these NOS2+ MΦ.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Results

    NOS2 and MMR were representative markers for the M1 and M2 activation states, respectively.

    “Nitric oxide synthase 2 (NOS2) and MΦ mannose receptor (MMR) were representative markers for the M1 and M2 activation states, respectively (18–20) (Fig. 4 A–D).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [18] Arnold SA, et al. Lack of host SPARC enhances vascular function and tumor spread in an orthotopic murine model of pancreatic carcinoma. Dis Model Mech. 2010;3:57–72. doi: 10.1242/dmm.003228. [DOI] [PMC free article] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [19] Martinez FO, Helming L, Gordon S. Alternative activation of macrophages: An immunologic functional perspective. Annu Rev Immunol. 2009;27:451–483. doi: 10.1146/annurev.immunol.021908.132532. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [20] Mantovani A, et al. The chemokine system in diverse forms of macrophage activation and polarization. Trends Immunol. 2004;25:677–686. doi: 10.1016/j.it.2004.09.015. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data
    § Results

    Increased MMR expression, a marker of M2 polarization, suggests a shift toward a prohealing phenotype and may explain the enhanced neovascularization seen for porous scaffolds.

    “This increased MMR expression, a marker of M2 polarization, suggests a shift toward a prohealing phenotype and may explain the enhanced neovascularization seen for porous scaffolds.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Discussion

    Previous in vivo studies demonstrated concurrent expression of M1 and M2 markers, and enhanced expression of M2 markers has been associated with improved outcomes for implanted biologic scaffolds.

    “Previous in vivo studies demonstrated concurrent expression of M1 and M2 markers (37), and enhanced expression of M2 markers has been associated with improved outcomes for implanted biologic scaffolds (34).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [37] Daley JM, Brancato SK, Thomay AA, Reichner JS, Albina JE. The phenotype of murine wound macrophages. J Leukoc Biol. 2010;87:59–67. doi: 10.1189/jlb.0409236. [DOI] [PMC free article] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [34] Brown BN, Valentin JE, Stewart-Akers AM, McCabe GP, Badylak SF. Macrophage phenotype and remodeling outcomes in response to biologic scaffolds with and without a cellular component. Biomaterials. 2009;30:1482–1491. doi: 10.1016/j.biomaterials.2008.11.040. [DOI] [PMC free article] [PubMed] [Google Scholar] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given
    § Materials and Methods

    All animal experiments adhered to federal guidelines and were approved by the University of Washington Animal Care and Use Committee.

    “All animal experiments adhered to federal guidelines and were approved by the University of Washington Animal Care and Use Committee.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § Discussion

    Rod-like scaffold constructs could feasibly be implanted in infarcted human hearts using minimally invasive catheter introduction systems.

    “Rod-like scaffold constructs could feasibly be implanted in infarcted human hearts using minimally invasive catheter introduction systems.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Discussion

    Pore size effects observed here relate to previous studies in which 10- to 45-μm pores filled with fibrohistiocytic tissue, whereas pores >45 μm filled with organized fibrous tissue.

    “Pore size effects observed here relate to previous studies in which 10- to 45-μm pores filled with fibrohistiocytic tissue, whereas pores >45 μm filled with organized fibrous tissue (31, 32).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [31] White R, et al. Effect of healing on small internal diameter arterial graft compliance. Biomater Med Devices Artif Organs. 1983;11:21–29. doi: 10.3109/10731198309118791. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

    • cites [32] Beahan P, Hull D. A study of the interface between a fibrous polyurethane arterial prosthesis and natural tissue. J Biomed Mater Res. 1982;16:827–838. doi: 10.1002/jbm.820160608. [DOI] [PubMed] [Google Scholar] source

      Not checked in the free run.

39 of 39

  • The paper relies on this without support.

    A scaffold system scaled to address diffusion limitations of static culture may enhance cell delivery by facilitating cell retention and survival.

    “A scaffold system scaled to address diffusion limitations of static culture may enhance cell delivery by facilitating cell retention and survival.”

  • The paper relies on this without support.

    Mechanical matching of the scaffold to host myocardium can permit load transfer to grafted cardiomyocytes to stimulate maturation and contractile coupling while minimizing tissue damage.

    “Mechanical matching of the scaffold to host myocardium can permit load transfer to grafted cardiomyocytes to stimulate maturation and contractile coupling while minimizing tissue damage.”

  • The paper relies on this without support.

    Cardiomyocytes have a high affinity for each other, with increased survival and formation of interconnected networks when cultured at high densities.

    “Cardiomyocytes have a high affinity for each other, with increased survival and formation of interconnected networks when cultured at high densities.”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Immunohistochemistry staining explained the angiogenic response to 30-40 μm pores was due to M2 phenotype activation, though identification was done by a single M1 and M2 marker, in which the M1 marker was also expressed in most of the M2 macrophages.

    “Immunohistochemistry staining explained the response was due to M2 phenotype activation, though identification was done by a single M1 and M2 marker, in which the M1 marker was also expressed in most of the M2 macrophages.”

    From Unraveling and Harnessing the Immune Response at the Cell–Biomaterial Interface for Tissue Engineering Purposes (2024) · cites this paper as [141]

    Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured

  • In vitro studies using monoculture cardiomyocytes showed sustainable cell viability and proliferation, but did not provide any insight on the difference between the pore sizes.

    “However, in vitro studies using monoculture cardiomyocytes showed sustainable cell viability and proliferation, but did not provide any insight on the difference between the pore sizes.”

    From Unraveling and Harnessing the Immune Response at the Cell–Biomaterial Interface for Tissue Engineering Purposes (2024) · cites this paper as [141]

    The Results and Discussion report that hESC-derived constructs became approximately 95% cardiomyocytes, remained viable in vitro for more than two weeks, and retained proliferative capacity for at least two weeks. They do not report an in vitro comparison of cardiomyocyte outcomes across pore sizes; pore-size effects were evaluated in acellular implants in vivo. The cultures were predominantly cardiomyocytes, not strict monocultures, and retained capacity to proliferate is narrower than demonstrated sustained proliferation. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • Implanting porous PHEMA-co-methacrylic acid hydrogels (0-80 μm pore size) in rats and mice demonstrated an even stronger angiogenic response with reduced encapsulation when pore sizes were tuned specifically to 30-40 μm.

    “Implanting these hydrogels in rats and mice demonstrated an even stronger angiogenic response with reduced encapsulation by tuning the pore sizes specifically to 30–40 µm.”

    From Unraveling and Harnessing the Immune Response at the Cell–Biomaterial Interface for Tissue Engineering Purposes (2024) · cites this paper as [141]

    The Results (page not available) conclude that 30–40 μm pores achieved maximal vascularization and minimal fibrous encapsulation in rat cardiac implants. However, the implantation experiments reported in this paper used rats, not mice. The Discussion also says vascularization did not differ significantly among pore sizes above the threshold, so 30–40 μm did not produce a uniquely stronger angiogenic response. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • Compared to non-porous controls, implants with 30-40 mm pores elicited significantly higher ratios of M2/M1 macrophages.

    “Further, when compared to the non-porous control, implants with 30–40 mm pores elicited a host response which was characterized by significantly higher ratios of M2/M1 macrophages [148].”

    From Macrophage polarization: an opportunity for improved outcomes in biomaterials and regenerative medicine (2012) · cites this paper as [148]

  • Porous biomaterials of the same composition as non-porous forms that elicit foreign body reaction and encapsulation heal with less encapsulation and more vascularity when implanted into dermis or cardiac tissues.

    “Recent studies have demonstrated that porous biomaterials of the same composition as those which, in their non-porous form, elicit an FBR and encapsulation heal with less encapsulation and more vascularity when implanted into either the dermis or into cardiac tissues [147–149].”

    From Macrophage polarization: an opportunity for improved outcomes in biomaterials and regenerative medicine (2012) · cites this paper as [148]

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. AJ Marshall, et al., Biomaterials with tightly controlled pore size that promote vascular in-growth. Polymer Preprints 45, 100–101 (2004).
  2. N Bursac, et al., Cardiac muscle tissue engineering: Toward an in vitro model for electrophysiological studies. Am J Physiol 277, H433–H444 (1999).

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Sorted by citations

Authors
Madden, L. R., Mortisen, D. J., Sussman, E. M., Dupras, S. K., Fugate, J. A., Cuy, J. L., Hauch, K. D., Laflamme, M. A., Murry, C. E., & Ratner, B. D.
Affiliations
University of Washington (US)
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2010-08-09
Volume
107
Issue
34
Pages
15211-15216
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.1006442107
PMC
PMC2930533
OpenAlex
W2106944257
Semantic Scholar
b1e8143bdd43d205d07ffc2a93eee6fb6f9b8362
Cited by
662
References
39
Citations by year
2026: 15 · 2025: 29 · 2024: 34 · 2023: 32 · 2022: 39 · 2021: 57 · 2020: 61 · 2019: 59 · 2018: 36 · 2017: 42 · 2016: 44 · 2015: 45 · 2014: 49 · 2013: 53 · 2012: 35
FWCI
39.77
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • University of Washington
  • National Institutes of Health (1u24dk076126-01, 5r01hl064387-10, DK076126)
  • National Heart, Lung, and Blood Institute (R01-HL064387, R01 HL64387, P01HL094374, R01HL084642)
  • National Institute of Diabetes and Digestive and Kidney Diseases (U24-DK076126)
Topics
  • Health Sciences › Medicine › Surgery › Tissue Engineering and Regenerative Medicine
  • Physical Sciences › Engineering › Biomedical Engineering › 3D Printing in Biomedical Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Medicine › Hydrogels: synthesis, properties, applications
Keywords
cardiac tissue engineering, human embryonic stem cell-derived cardiomyocytes, cardiac implantation, angiogenesis, fibrosis, macrophage polarization, M2 macrophages, scaffold pore size, vascularization
MeSH terms
Animals, Cell Count, Chick Embryo, Heart, Humans, Methacrylates, Microscopy, Electron, Scanning, Polyhydroxyethyl Methacrylate, Rats, Nude, Rats, Sprague-Dawley, Neovascularization, Physiologic, Hydrogels, Tissue Engineering, Ventricular Myosins, Myocytes, Cardiac, Rats, Tissue Scaffolds

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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