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Poleshko A, Shah PP, Gupta M, Babu A, Morley MP, Manderfield LJ, Ifkovits JL, Calderon D, Aghajanian H, Sierra-Pagán JE, Sun Z, Wang Q, Li L, Dubois NC, Morrisey EE, Lazar MA, Smith CL, Epstein JA, Jain R. Genome-Nuclear Lamina Interactions Regulate Cardiac Stem Cell Lineage Restriction. Cell 2017; 171:573-587.e14. [PMID: 29033129 DOI: 10.1016/j.cell.2017.09.018] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 08/25/2017] [Accepted: 09/12/2017] [Indexed: 01/15/2023]
Abstract
Progenitor cells differentiate into specialized cell types through coordinated expression of lineage-specific genes and modification of complex chromatin configurations. We demonstrate that a histone deacetylase (Hdac3) organizes heterochromatin at the nuclear lamina during cardiac progenitor lineage restriction. Specification of cardiomyocytes is associated with reorganization of peripheral heterochromatin, and independent of deacetylase activity, Hdac3 tethers peripheral heterochromatin containing lineage-relevant genes to the nuclear lamina. Deletion of Hdac3 in cardiac progenitor cells releases genomic regions from the nuclear periphery, leading to precocious cardiac gene expression and differentiation into cardiomyocytes; in contrast, restricting Hdac3 to the nuclear periphery rescues myogenesis in progenitors otherwise lacking Hdac3. Our results suggest that availability of genomic regions for activation by lineage-specific factors is regulated in part through dynamic chromatin-nuclear lamina interactions and that competence of a progenitor cell to respond to differentiation signals may depend upon coordinated movement of responding gene loci away from the nuclear periphery.
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Affiliation(s)
- Andrey Poleshko
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Parisha P Shah
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mudit Gupta
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Apoorva Babu
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael P Morley
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lauren J Manderfield
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jamie L Ifkovits
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Damelys Calderon
- Department of Cell, Developmental, and Regenerative Biology, Mindich Child Health and Development Institute, and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Haig Aghajanian
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Javier E Sierra-Pagán
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Zheng Sun
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and the Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Qiaohong Wang
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Li Li
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nicole C Dubois
- Department of Cell, Developmental, and Regenerative Biology, Mindich Child Health and Development Institute, and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Edward E Morrisey
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mitchell A Lazar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and the Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Cheryl L Smith
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan A Epstein
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Rajan Jain
- Departments of Medicine and Cell and Developmental Biology, Institute for Regenerative Medicine, and the Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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Jain R, Li D, Gupta M, Manderfield LJ, Ifkovits JL, Wang Q, Liu F, Liu Y, Poleshko A, Padmanabhan A, Raum JC, Li L, Morrisey EE, Lu MM, Won KJ, Epstein JA. HEART DEVELOPMENT. Integration of Bmp and Wnt signaling by Hopx specifies commitment of cardiomyoblasts. Science 2015; 348:aaa6071. [PMID: 26113728 DOI: 10.1126/science.aaa6071] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cardiac progenitor cells are multipotent and give rise to cardiac endothelium, smooth muscle, and cardiomyocytes. Here, we define and characterize the cardiomyoblast intermediate that is committed to the cardiomyocyte fate, and we characterize the niche signals that regulate commitment. Cardiomyoblasts express Hopx, which functions to coordinate local Bmp signals to inhibit the Wnt pathway, thus promoting cardiomyogenesis. Hopx integrates Bmp and Wnt signaling by physically interacting with activated Smads and repressing Wnt genes. The identification of the committed cardiomyoblast that retains proliferative potential will inform cardiac regenerative therapeutics. In addition, Bmp signals characterize adult stem cell niches in other tissues where Hopx-mediated inhibition of Wnt is likely to contribute to stem cell quiescence and to explain the role of Hopx as a tumor suppressor.
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Affiliation(s)
- Rajan Jain
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Deqiang Li
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mudit Gupta
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lauren J Manderfield
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jamie L Ifkovits
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Qiaohong Wang
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Feiyan Liu
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ying Liu
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrey Poleshko
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Arun Padmanabhan
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeffrey C Raum
- Department of Genetics, Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Li Li
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edward E Morrisey
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Min Min Lu
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kyoung-Jae Won
- Department of Genetics, Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan A Epstein
- Department of Cell and Developmental Biology, Penn Cardiovascular Institute, Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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Ifkovits JL, Addis RC, Epstein JA, Gearhart JD. Inhibition of TGFβ signaling increases direct conversion of fibroblasts to induced cardiomyocytes. PLoS One 2014; 9:e89678. [PMID: 24586958 PMCID: PMC3935923 DOI: 10.1371/journal.pone.0089678] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 01/21/2014] [Indexed: 12/20/2022] Open
Abstract
Recent studies have been successful at utilizing ectopic expression of transcription factors to generate induced cardiomyocytes (iCMs) from fibroblasts, albeit at a low frequency in vitro. This work investigates the influence of small molecules that have been previously reported to improve differentiation to cardiomyocytes as well as reprogramming to iPSCs in conjunction with ectopic expression of the transcription factors Hand2, Nkx2.5, Gata4, Mef2C, and Tbx5 on the conversion to functional iCMs. We utilized a reporter system in which the calcium indicator GCaMP is driven by the cardiac Troponin T promoter to quantify iCM yield. The TGFβ inhibitor, SB431542 (SB), was identified as a small molecule capable of increasing the conversion of both mouse embryonic fibroblasts and adult cardiac fibroblasts to iCMs up to ∼5 fold. Further characterization revealed that inhibition of TGFβ by SB early in the reprogramming process led to the greatest increase in conversion of fibroblasts to iCMs in a dose-responsive manner. Global transcriptional analysis at Day 3 post-induction of the transcription factors revealed an increased expression of genes associated with the development of cardiac muscle in the presence of SB compared to the vehicle control. Incorporation of SB in the reprogramming process increases the efficiency of iCM generation, one of the major goals necessary to enable the use of iCMs for discovery-based applications and for the clinic.
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Affiliation(s)
- Jamie L. Ifkovits
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (JLI); (JDG)
| | - Russell C. Addis
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jonathan A. Epstein
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - John D. Gearhart
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (JLI); (JDG)
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Dishowitz MI, Zhu F, Sundararaghavan HG, Ifkovits JL, Burdick JA, Hankenson KD. Jagged1 immobilization to an osteoconductive polymer activates the Notch signaling pathway and induces osteogenesis. J Biomed Mater Res A 2013; 102:1558-67. [PMID: 23775982 DOI: 10.1002/jbm.a.34825] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/16/2013] [Accepted: 05/31/2013] [Indexed: 12/21/2022]
Abstract
Treatment of nonunion fractures is a significant problem. Common therapeutics, including autologous bone grafts and bone morphogenetic proteins, show well-established limitations. Therefore, a need persists for the identification of novel clinical therapies to promote healing. The Notch signaling pathway regulates bone development. Clinically, loss-of-function mutations to the Notch ligand Jagged1 decrease bone mass and increase fracture risk. Jagged1 is also the most highly upregulated ligand during fracture repair, identifying it as a potential target to promote bone formation. Therefore, the objective of this study was to develop a clinically translatable construct comprised of Jagged1 and an osteoconductive scaffold, and characterize its activity in human mesenchymal stem cells (hMSC). We first evaluated the effects of Jagged1 directly immobilized to a novel poly(β-amino ester) relative to indirect coupling via antibody. Direct was more effective at activating hMSC Notch target gene expression and osteogenic activity. We then found that directly immobilized Jagged1 constructs induced osteoblast differentiation. This is the first study to demonstrate that Jagged1 delivery transiently activates Notch signaling and increases osteogenesis. A positive correlation was found between Jagged1-induced Notch and osteogenic expression. Collectively, these results indicate that Jagged1 coupled to an osteogenic biomaterial could promote bone tissue formation during fracture healing.
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Affiliation(s)
- Michael I Dishowitz
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
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Addis RC, Ifkovits JL, Pinto F, Kellam LD, Esteso P, Rentschler S, Christoforou N, Epstein JA, Gearhart JD. Optimization of direct fibroblast reprogramming to cardiomyocytes using calcium activity as a functional measure of success. J Mol Cell Cardiol 2013; 60:97-106. [PMID: 23591016 PMCID: PMC3679282 DOI: 10.1016/j.yjmcc.2013.04.004] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/03/2013] [Accepted: 04/05/2013] [Indexed: 01/14/2023]
Abstract
Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persist for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently than previously published methods.
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Affiliation(s)
- Russell C. Addis
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jamie L. Ifkovits
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Filipa Pinto
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Lori D. Kellam
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Paul Esteso
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Stacey Rentschler
- Department of Internal Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | | | - Jonathan A. Epstein
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - John D. Gearhart
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Tous E, Ifkovits JL, Koomalsingh KJ, Shuto T, Soeda T, Kondo N, Gorman JH, Gorman RC, Burdick JA. Influence of injectable hyaluronic acid hydrogel degradation behavior on infarction-induced ventricular remodeling. Biomacromolecules 2011; 12:4127-35. [PMID: 21967486 PMCID: PMC3246217 DOI: 10.1021/bm201198x] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Increased myocardial wall stress after myocardial infarction (MI) initiates the process of adverse left ventricular (LV) remodeling that is manifest as progressive LV dilatation, loss of global contractile function, and symptomatic heart failure, and recent work has shown that reduction in wall stress through injectable bulking agents attenuates these outcomes. In this study, hyaluronic acid (HA) was functionalized to exhibit controlled and tunable mechanics and degradation once cross-linked, in an attempt to assess the temporal dependency of mechanical stabilization in LV remodeling. Specifically, two hydrolytically degrading (low and high HeMA-HA, degrading in ~3 and 10 weeks, respectively) and two stable (low and high MeHA, little mass loss even after 8 weeks) hydrogels with similar initial mechanics (low: ~7 kPa; high: ~35-40 kPa) were evaluated in an ovine model of MI. Generally, the more stable hydrogels maintained myocardial wall thickness in the apical and basilar regions more efficiently (low MeHA: apical: 6.5 mm, basilar: 7 mm, high MeHA: apical: 7.0 mm basilar: 7.2 mm) than the hydrolytically degrading hydrogels (low HeMA-HA: apical: 3.5 mm, basilar: 6.0 mm, high HeMA-HA: apical: 4.1 mm, basilar: 6.1 mm); however, all hydrogel groups were improved compared to infarct controls (IC) (apical: 2.2 mm, basilar: 4.6 mm). Histological analysis at 8 weeks demonstrated that although both degradable hydrogels resulted in increased inflammation, all treatments resulted in increased vessel formation compared to IC. Further evaluation revealed that while high HeMA-HA and high MeHA maintained reduced LV volumes at 2 weeks, high MeHA was more effective at 8 weeks, implying that longer wall stabilization is needed for volume maintenance. All hydrogel groups resulted in better cardiac output (CO) values than IC.
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Affiliation(s)
- Elena Tous
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jamie L. Ifkovits
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Kevin J. Koomalsingh
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Takashi Shuto
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Toru Soeda
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Norihiro Kondo
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Joseph H. Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Robert C. Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Glenolden, PA, 19036, USA
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Abstract
Fibrous scaffolds are finding wide use in the field of tissue engineering, as they can be designed to mimic many native tissue properties and structures (e.g., cardiac tissue, meniscus). The influence of fiber alignment and scaffold architecture on cellular interactions and matrix organization was the focus of this study. Three scaffolds were fabricated from the photocrosslinkable elastomer poly(glycerol sebacate) (PGS), with changes in fiber alignment (non-aligned (NA) versus aligned (AL)) and the introduction of a PEO sacrificial polymer population to the AL scaffold (composite (CO)). PEO removal led to an increase in scaffold porosity and maintenance of scaffold anisotropy, as evident through visualization, mechanical testing, and mass loss studies. Hydrated scaffolds possessed moduli that ranged between ∼3-240 kPa, failing within the range of properties (<300 kPa) appropriate for soft tissue engineering. CO scaffolds were completely degraded as early as 16 days, whereas NA and AL scaffolds had ∼90% mass loss after 21 days when monitored in vitro. Neonatal cardiomyocytes, used as a representative cell type, that were seeded onto the scaffolds maintained their viability and aligned along the surface of the AL and CO fibers. When implanted subcutaneously in rats, a model that is commonly used to investigate in vivo tissue responses to biomaterials, CO scaffolds were completely integrated at 2 weeks, whereas ∼13% and ∼16% of the NA and AL scaffolds, respectively remained acellular. However, all scaffolds were completely populated with cells at 4 weeks post-implantation. Polarized light microscopy was used to evaluate the collagen elaboration and orientation within the scaffold. An increase in the amount of collagen was observed for CO scaffolds and enhanced alignment of the nascent collagen was observed for AL and CO scaffolds compared to NA scaffolds. Thus, these results indicate that the scaffold architecture and porosity are important considerations in controlling tissue formation.
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Affiliation(s)
- Jamie L. Ifkovits
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Katherine Wu
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Robert L. Mauck
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Metter RB, Ifkovits JL, Hou K, Vincent L, Hsu B, Wang L, Mauck RL, Burdick JA. Biodegradable fibrous scaffolds with diverse properties by electrospinning candidates from a combinatorial macromer library. Acta Biomater 2010; 6:1219-26. [PMID: 19853066 DOI: 10.1016/j.actbio.2009.10.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 10/02/2009] [Accepted: 10/15/2009] [Indexed: 11/20/2022]
Abstract
The properties of electrospun fibrous scaffolds, including degradation, mechanics and cellular interactions, are important for their use in tissue engineering applications. Although some diversity has been obtained previously in fibrous scaffolds, optimization of scaffold properties relies on iterative techniques in both polymer synthesis and processing. Here, we electrospun candidates from a combinatorial library of biodegradable and photopolymerizable poly(beta-amino ester)s (PBAEs) to show that the diversity in properties found in this library is retained when processed into fibrous scaffolds. Specifically, three PBAE macromers were electrospun into scaffolds and possessed similar initial mechanical properties, but exhibited mass loss ranging from rapid (complete degradation within approximately 2 weeks) to moderate (complete degradation within approximately 3 months) to slow (only partial degradation after 3 months). These trends in mechanics and degradation mimicked what was previously observed in the bulk polymers. Although cellular adhesion was dependent on the polymer composition in films, adhesion to scaffolds that were electrospun with gelatin was similar on all formulations and controls. To further illustrate the diverse properties that are attainable in these systems, the fastest and slowest degrading polymers were electrospun together into one scaffold, but as distinct fiber populations. This dual-polymer scaffold exhibited behavior in mass loss and mechanics with time that fell between the single-polymer scaffolds. In general, this work indicates that combinatorial libraries may be an important source of information and specific polymer compositions for the fabrication of electrospun fibrous scaffolds with tunable properties.
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Affiliation(s)
- Robert B Metter
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S. 33rd Street, Philadelphia, PA 19104, USA
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9
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Abstract
As the field of tissue engineering evolves, there is a tremendous demand to produce more suitable materials and processing techniques in order to address the requirements (e.g., mechanics and vascularity) of more intricate organs and tissues. Electrospinning is a popular technique to create fibrous scaffolds that mimic the architecture and size scale of the native extracellular matrix. These fibrous scaffolds are also useful as cell culture substrates since the fibers can be used to direct cellular behavior, including stem cell differentiation (see extensive reviews by Mauck et al. and Sill et al. for more information). In this article, we describe the general process of electrospinning polymers and as an example, electrospin a reactive hyaluronic acid capable of crosslinking with light exposure (see Ifkovits et al. for a review on photocrosslinkable materials). We also introduce further processing capabilities such as photopatterning and multi-polymer scaffold formation. Photopatterning can be used to create scaffolds with channels and multi-scale porosity to increase cellular infiltration and tissue distribution. Multi-polymer scaffolds are useful to better tune the properties (mechanics and degradation) of a scaffold, including tailored porosity for cellular infiltration. Furthermore, these techniques can be extended to include a wide array of polymers and reactive macromers to create complex scaffolds that provide the cues necessary for the development of successful tissue engineered constructs.
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10
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Ifkovits JL, Devlin JJ, Eng G, Martens TP, Vunjak-Novakovic G, Burdick JA. Biodegradable fibrous scaffolds with tunable properties formed from photo-cross-linkable poly(glycerol sebacate). ACS Appl Mater Interfaces 2009; 1:1878-86. [PMID: 20160937 PMCID: PMC2765054 DOI: 10.1021/am900403k] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
It is becoming increasingly apparent that the architecture and mechanical properties of scaffolds, particularly with respect to mimicking features of natural tissues, are important for tissue engineering applications. Acrylated poly(glycerol sebacate) (Acr-PGS) is a material that can be cross-linked upon exposure to ultraviolet light, leading to networks with tunable mechanical and degradation properties through simple changes during Acr-PGS synthesis. For example, the number of acrylate functional groups on the macromer dictates the concentration of cross-links formed in the resulting network. Three macromers were synthesized that form networks that vary dramatically with respect to their tensile modulus ( approximately 30 kPa to 6.6 MPa) and degradation behavior ( approximately 20-100% mass loss at 12 weeks) based on the extent of acrylation ( approximately 1-24%). These macromers were processed into biodegradable fibrous scaffolds using electrospinning, with gelatin as a carrier polymer to facilitate fiber formation and cell adhesion. The resulting scaffolds were also diverse with respect to their mechanics (tensile modulus ranging from approximately 60 kPa to 1 MPa) and degradation ( approximately 45-70% mass loss by 12 weeks). Mesenchymal stem cell adhesion and proliferation on all fibrous scaffolds was indistinguishable from those of controls. The scaffolds showed similar diversity when implanted on the surface of hearts in a rat model of acute myocardial infarction and demonstrated a dependence on the scaffold thickness and chemistry in the host response. In summary, these diverse scaffolds with tailorable chemical, structural, mechanical, and degradation properties are potentially useful for the engineering of a wide range of soft tissues.
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Affiliation(s)
- Jamie L. Ifkovits
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Jeffrey J. Devlin
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - George Eng
- Department of Biomedical Engineering, Columbia University, New York, New York 10032
| | - Timothy P. Martens
- Department of Biomedical Engineering, Columbia University, New York, New York 10032
| | | | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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11
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Abstract
Shape-memory materials (including polymers, metals, and ceramics) are those that are processed into a temporary shape and respond to some external stimuli (e.g., temperature) to undergo a transition back to a permanent shape.[1 , 2 ] Shape memory polymers are finding use in a range of applications from aerospace to fabrics, to biomedical devices and microsystem components.[3 –5 ] For many applications, it would be beneficial to initiate heating with an external trigger (e.g., transdermal light exposure). In this work, we formulated composites of gold nanorods (<1% by volume) and biodegradable networks, where exposure to infrared light induced heating and consequently, shape transitions. The heating is repeatable and tunable based on nanorod concentration and light intensity and the nanorods did not alter the cytotoxicity or in vivo tissue response to the networks.
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Affiliation(s)
- Kolin C. Hribar
- Department of Bioengineering, University of Pennsylvania, 210 S 33th Street, Philadelphia, PA 19104 (USA)
| | - Robert B. Metter
- Department of Bioengineering, University of Pennsylvania, 210 S 33th Street, Philadelphia, PA 19104 (USA)
| | - Jamie L. Ifkovits
- Department of Bioengineering, University of Pennsylvania, 210 S 33th Street, Philadelphia, PA 19104 (USA)
| | - Thomas Troxler
- Department of Chemistry Regional Laser and Biomedical Technology Laboratories, University of Pennsylvania
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, 210 S 33th Street, Philadelphia, PA 19104 (USA)
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12
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Tan AR, Ifkovits JL, Baker BM, Brey DM, Mauck RL, Burdick JA. Electrospinning of photocrosslinked and degradable fibrous scaffolds. J Biomed Mater Res A 2009; 87:1034-43. [PMID: 18257065 DOI: 10.1002/jbm.a.31853] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Electrospun fibrous scaffolds are being developed for the engineering of numerous tissues. Advantages of electrospun scaffolds include the similarity in fiber diameter to elements of the native extracellular matrix and the ability to align fibers within the scaffold to control and direct cellular interactions and matrix deposition. To further expand the range of properties available in fibrous scaffolds, we developed a process to electrospin photocrosslinkable macromers from a library of multifunctional poly(beta-amino ester)s. In this study, we utilized one macromer (A6) from this library for initial examination of fibrous scaffold formation. A carrier polymer [poly(ethylene oxide) (PEO)] was used for fiber formation because of limitations in electrospinning A6 alone. Various ratios of A6 and PEO were successfully electrospun and influenced the scaffold fiber diameter and appearance. When electrospun with a photoinitiator and exposed to light, the macromers crosslinked rapidly to high double bond conversions and fibrous scaffolds displayed higher elastic moduli compared to uncrosslinked scaffolds. When these fibers were deposited onto a rotating mandrel and crosslinked, organized fibrous scaffolds were obtained, which possessed higher moduli (approximately 4-fold) in the fiber direction than perpendicular to the fiber direction, as well as higher moduli (approximately 12-fold) than that of nonaligned crosslinked scaffolds. With exposure to water, a significant mass loss and a decrease in mechanical properties were observed, correlating to a rapid initial loss of PEO which reached an equilibrium after 7 days. Overall, these results present a process that allows for formation of fibrous scaffolds from a wide variety of possible photocrosslinkable macromers, increasing the diversity and range of properties achievable in fibrous scaffolds for tissue regeneration.
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Affiliation(s)
- Andrea R Tan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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13
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Charati MB, Ifkovits JL, Burdick JA, Linhardt JG, Kiick KL. Hydrophilic elastomeric biomaterials based on resilin-like polypeptides. Soft Matter 2009; 5:3412-3416. [PMID: 20543970 PMCID: PMC2883189 DOI: 10.1039/b910980c] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The production of complex, yet well defined materials offers many opportunities in regenerative medicine, in which the mechanical and biological properties of the matrix must meet stringent requirements. Here we report the recombinant production of modular polypeptidic materials, based on the highly resilient protein resilin, which are equipped with multiple biologically active domains. The recombinant materials exhibit useful mechanical and cell adhesion behavior.
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Affiliation(s)
- Manoj B. Charati
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
| | - Jamie L. Ifkovits
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Kristi L. Kiick
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
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14
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15
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Brey DM, Ifkovits JL, Mozia RI, Katz JS, Burdick JA. Controlling poly(beta-amino ester) network properties through macromer branching. Acta Biomater 2008; 4:207-17. [PMID: 18033746 DOI: 10.1016/j.actbio.2007.10.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2007] [Revised: 09/14/2007] [Accepted: 10/08/2007] [Indexed: 11/15/2022]
Abstract
Photopolymerizable and degradable biomaterials are becoming important in the development of advanced materials in the fields of tissue engineering, drug delivery, and microdevices. We have recently developed a library of poly(beta-amino ester)s (PBAEs) that form networks with a wide range of mechanical properties and degradation rates that are controlled by simple alterations in the macromer molecular weight or chemical structure. In this study, the influence of macromer branching on network properties was assessed by adding the trifunctional monomer pentaerythritol triacrylate (PETA) during synthesis. This led to a dose-dependent increase in the network compressive modulus, tensile modulus, and glass transition temperature, and a decrease in the network soluble fraction, yet led to only minor variations in degradation profiles and reaction behavior. For instance, the tensile modulus increased from 1.98+/-0.09MPa to 3.88+/-0.20MPa when the macromer went from a linear structure to a more branched structure with the addition of PETA. When osteoblast-like cells were grown on thin films, there was an increase in cell adhesion and spreading as the amount of PETA incorporated during synthesis increased. Towards tissue engineering applications, porous scaffolds were fabricated by photopolymerizing around a poragen and then subsequently leaching the poragen. Interconnected pores were observed in the scaffolds and observed trends translated to the porous scaffold (i.e., increasing mechanics with increasing branching). These findings demonstrate a simple variation during macromer synthesis that can be used to further tune the physical properties of scaffolds for given applications, particularly for candidates from the PBAE library.
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Affiliation(s)
- Darren M Brey
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S. 33rd Street, Philadelphia, PA 19104, USA
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16
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Abstract
Photopolymerizable and degradable biomaterials are finding widespread application in the field of tissue engineering for the engineering of tissues such as bone, cartilage, and liver. The spatial and temporal control afforded by photoinitiated polymerizations has allowed for the development of injectable materials that can deliver cells and growth factors, as well as for the fabrication of scaffolding with complex structures. The materials developed for these applications range from entirely synthetic polymers (e.g., poly(ethylene glycol)) to purely natural polymers (e.g., hyaluronic acid) that are modified with photoreactive groups, with degradation based on the hydrolytic or enzymatic degradation of bonds in the polymer backbone or crosslinks. The degradation behavior also ranges from purely bulk to entirely surface degrading, based on the nature of the backbone chemistry and type of degradable units. The mechanical properties of these polymers are primarily based on factors such as the network crosslinking density and polymer concentration. As we better understand biological features necessary to control cellular behavior, smarter materials are being developed that can incorporate and mimic many of these factors.
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Affiliation(s)
- Jamie L Ifkovits
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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