Publications by authors named "Nevin Witman"

19 Publications

  • Page 1 of 1

Yohimbine Directly Induces Cardiotoxicity on Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Cardiovasc Toxicol 2021 Nov 24. Epub 2021 Nov 24.

Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, 1678 Dong Fang Road, Shanghai, 200127, China.

Yohimbine is a highly selective and potent α-adrenoceptor antagonist, which is usually treated as an adjunction for impotence, as well for weight loss and natural bodybuilding aids. However, it was recently reported that Yohimbine causes myocardial injury and controversial results were reported in the setting of cardiac diseases. Here, we used human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) as a model system to explore electrophysiologic characterization after exposure to Yohimbine. HiPSC-CMs were differentiated by employment of inhibitory Wnt compounds. For analysis of electrophysiological properties, conventional whole-cell patch-clamp recording was used. Specifically, spontaneous action potentials, pacemaker currents (I), sodium (Na) channel (I), and calcium (Ca) channel currents (I) were assessed in hiPSC-CMs after exposure to Yohimbine. HiPSC-CMs expressed sarcomeric-α-actinin and MLC2V proteins, as well as exhibited ventricular-like spontaneous action potential waveform. Yohimbine inhibited frequency of hiPSC-CMs spontaneous action potentials and significantly prolonged action potential duration in a dose-dependent manner. In addition, rest potential, threshold potential, amplitude, and maximal diastolic potential were decreased, whereas APD/APD was prolonged. Yohimbine inhibited the amplitude of I in low doses (IC = 14.2 μM, n = 5) and inhibited I in high doses (IC = 139.7 μM, n = 5). Whereas Yohimbine did not affect the activation curves, treatment resulted in left shifts in inactivation curves of both Na and Ca channels. Here, we show that Yohimbine induces direct cardiotoxic effects on spontaneous action potentials of I and I in hiPSC-CMs. Importantly, these effects were not mediated by α-adrenoceptor signaling. Our results strongly suggest that Yohimbine directly and negatively affects electrophysiological properties of human cardiomyocytes. These findings are highly relevant for potential application of Yohimbine in patients with atrioventricular conduction disorder.
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http://dx.doi.org/10.1007/s12012-021-09709-3DOI Listing
November 2021

An mRNA assay system demonstrates proteasomal-specific degradation contributes to cardiomyopathic phospholamban null mutation.

Mol Med 2021 09 8;27(1):102. Epub 2021 Sep 8.

Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.

Background: The human L39X phospholamban (PLN) cardiomyopathic mutant has previously been reported as a null mutation but the detailed molecular pathways that lead to the complete lack of detectable protein remain to be clarified. Previous studies have shown the implication between an impaired cellular degradation homeostasis and cardiomyopathy development. Therefore, uncovering the underlying mechanism responsible for the lack of PLN protein has important implications in understanding the patient pathology, chronic human calcium dysregulation and aid the development of potential therapeutics.

Methods: A panel of mutant and wild-type reporter tagged PLN modified mRNA (modRNA) constructs were transfected in human embryonic stem cell-derived cardiomyocytes. Lysosomal and proteasomal chemical inhibitors were used together with cell imaging and protein analysis tools in order to dissect degradation pathways associated with expressed PLN constructs. Transcriptional profiling of the cardiomyocytes transfected by wild-type or L39X mutant PLN modRNA was analysed with bulk RNA sequencing.

Results: Our modRNA assay system revealed that transfected L39X mRNA was stable and actively translated in vitro but with only trace amount of protein detectable. Proteasomal inhibition of cardiomyocytes transfected with L39X mutant PLN modRNA showed a fourfold increase in protein expression levels. Additionally, RNA sequencing analysis of protein degradational pathways showed a significant distinct transcriptomic signature between wild-type and L39X mutant PLN modRNA transfected cardiomyocytes.

Conclusion: Our results demonstrate that the cardiomyopathic PLN null mutant L39X is rapidly, actively and specifically degraded by proteasomal pathways. Herein, and to the best of our knowledge, we report for the first time the usage of modified mRNAs to screen for and illuminate alternative molecular pathways found in genes associated with inherited cardiomyopathies.
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http://dx.doi.org/10.1186/s10020-021-00362-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8425124PMC
September 2021

Amnion signals are essential for mesoderm formation in primates.

Nat Commun 2021 08 26;12(1):5126. Epub 2021 Aug 26.

Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.

Embryonic development is largely conserved among mammals. However, certain genes show divergent functions. By generating a transcriptional atlas containing >30,000 cells from post-implantation non-human primate embryos, we uncover that ISL1, a gene with a well-established role in cardiogenesis, controls a gene regulatory network in primate amnion. CRISPR/Cas9-targeting of ISL1 results in non-human primate embryos which do not yield viable offspring, demonstrating that ISL1 is critically required in primate embryogenesis. On a cellular level, mutant ISL1 embryos display a failure in mesoderm formation due to reduced BMP4 signaling from the amnion. Via loss of function and rescue studies in human embryonic stem cells we confirm a similar role of ISL1 in human in vitro derived amnion. This study highlights the importance of the amnion as a signaling center during primate mesoderm formation and demonstrates the potential of in vitro primate model systems to dissect the genetics of early human embryonic development.
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http://dx.doi.org/10.1038/s41467-021-25186-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390679PMC
August 2021

Dexmedetomidine exhibits antiarrhythmic effects on human-induced pluripotent stem cell-derived cardiomyocytes through a Na/Ca channel-mediated mechanism.

Ann Transl Med 2021 Mar;9(5):399

Department of Pediatric Cardiothoracic Surgery, Shanghai Children's Medical Center; School of Medicine, Shanghai Jiao Tong University, Shanghai, China.

Background: Ventricular-like human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exhibit the electrophysiological characteristics of spontaneous beating. Previous studies demonstrated that dexmedetomidine (DMED), a highly selective and widely used α-adrenoceptor agonist for sedation, analgesia, and stress management, may induce antiarrhythmic effects, especially ventricular tachycardia. However, the underlying mechanisms of the DMED-mediated antiarrhythmic effects remain to be fully elucidated.

Methods: A conventional patch-clamp recording method was used to investigate the direct effects of DMED on spontaneous action potentials, pacemaker currents ( ), potassium (K) channel currents ( and ), sodium (Na) channel currents ( ), and calcium (Ca) channel currents ( ) in ventricular-like hiPSC-CMs.

Results: DMED dose-dependently altered the frequency of ventricular-like spontaneous action potentials with a half-maximal inhibitory concentration (IC) of 27.9 µM (n=6) and significantly prolonged the action potential duration at 90% repolarization (APD). DMED also inhibited the amplitudes of the and without affecting the activation and inactivation curves of these channels. DMED decreased the time constant of the Na and Ca channel activation at potential -40 to -20 mv, and -20 mv. DMED increased the time constant of inactivation of the Na and Ca channels. However, DMED did not affect the , , , and their current-voltage relationship. The ability of DMED to decrease the spontaneous action potential frequency and the Na and Ca channel amplitudes, were not blocked by yohimbine, idazoxan, or phentolamine.

Conclusions: DMED could inhibit the frequency of spontaneous action potentials and decrease the and of hiPSC-CMs via mechanisms that were independent of the α-adrenoceptor, the imidazoline receptor, and the α-adrenoceptor. These inhibitory effects on hiPSC-CMs may contribute to the antiarrhythmic effects of DMED.
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http://dx.doi.org/10.21037/atm-20-5898DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033317PMC
March 2021

BMP-2 and VEGF-A modRNAs in collagen scaffold synergistically drive bone repair through osteogenic and angiogenic pathways.

Commun Biol 2021 01 19;4(1):82. Epub 2021 Jan 19.

Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, 1678 Dong Fang Road, 200127, Shanghai, China.

Bone has a remarkable potential for self-healing and repair, yet several injury types are non-healing even after surgical or non-surgical treatment. Regenerative therapies that induce bone repair or improve the rate of recovery are being intensely investigated. Here, we probed the potential of bone marrow stem cells (BMSCs) engineered with chemically modified mRNAs (modRNA) encoding the hBMP-2 and VEGF-A gene to therapeutically heal bone. Induction of osteogenesis from modRNA-treated BMSCs was confirmed by expression profiles of osteogenic related markers and the presence of mineralization deposits. To test for therapeutic efficacy, a collagen scaffold inoculated with modRNA-treated BMSCs was explored in an in vivo skull defect model. We show that hBMP-2 and VEGF-A modRNAs synergistically drive osteogenic and angiogenic programs resulting in superior healing properties. This study exploits chemically modified mRNAs, together with biomaterials, as a potential approach for the clinical treatment of bone injury and defects.
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http://dx.doi.org/10.1038/s42003-020-01606-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815925PMC
January 2021

Human adipose-derived stem cells enriched with VEGF-modified mRNA promote angiogenesis and long-term graft survival in a fat graft transplantation model.

Stem Cell Res Ther 2020 11 19;11(1):490. Epub 2020 Nov 19.

Department of Ophthalmology, Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China.

Background: Fat grafting, as a standard treatment for numerous soft tissue defects, remains unpredictable and technique-dependent. Human adipose-derived stem cells (hADSCs) are promising candidates for cell-assisted therapy to improve graft survival. As free-living fat requires nutritional and respiratory sources to thrive, insufficient and unstable vascularization still impedes hADSC-assisted therapy. Recently, cytotherapy combined with modified mRNA (modRNA) encoding vascular endothelial growth factor (VEGF) has been applied for the treatment of ischemia-related diseases. Herein, we hypothesized that VEGF modRNA (modVEGF)-engineered hADSCs could robustly enhance fat survival in a fat graft transplantation model.

Methods: hADSCs were acquired from lipoaspiration and transfected with modRNAs. Transfection efficiency and expression kinetics of modRNAs in hADSCs were first evaluated in vitro. Next, we applied an in vivo Matrigel plug assay to assess the viability and angiogenic potential of modVEGF-engineered hADSCs at 1 week post-implantation. Finally, modVEGF-engineered hADSCs were co-transplanted with human fat in a murine model to analyze the survival rate, re-vascularization, proliferation, fibrosis, apoptosis, and necrosis of fat grafts over long-term follow-up.

Results: Transfections of modVEGF in hADSCs were highly tolerable as the modVEGF-engineered hADSCs facilitated burst-like protein production of VEGF in both our in vitro and in vivo models. modVEGF-engineered hADSCs induced increased levels of cellular proliferation and proangiogenesis when compared to untreated hADSCs in both ex vivo and in vivo assays. In a fat graft transplantation model, we provided evidence that modVEGF-engineered hADSCs promote the optimal potency to preserve adipocytes, especially in the long-term post-transplantation phase. Detailed histological analysis of fat grafts harvested at 15, 30, and 90 days following in vivo grafting suggested the release of VEGF protein from modVEGF-engineered hADSCs significantly improved neo-angiogenesis, vascular maturity, and cell proliferation. The modVEGF-engineered hADSCs also significantly mitigated the presence of fibrosis, apoptosis, and necrosis of grafts when compared to the control groups. Moreover, modVEGF-engineered hADSCs promoted graft survival and cell differentiation abilities, which also induced an increase in vessel formation and the number of surviving adipocytes after transplantation.

Conclusion: This current study demonstrates the employment of modVEGF-engineered hADSCs as an advanced alternative to the clinical treatment involving soft-tissue reconstruction and rejuvenation.
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http://dx.doi.org/10.1186/s13287-020-02008-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7678328PMC
November 2020

Corrigendum to "Cardiac progenitors and paracrine mediators in cardiogenesis and heart regeneration" [Semin. Cell Dev. Biol. Vol.100 (2020) 29-51].

Semin Cell Dev Biol 2021 Jan 7;109:151. Epub 2020 Oct 7.

Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden; Department of Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden. Electronic address:

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http://dx.doi.org/10.1016/j.semcdb.2020.09.008DOI Listing
January 2021

Intrinsic Color Sensing System Allows for Real-Time Observable Functional Changes on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

ACS Nano 2020 07 8;14(7):8232-8246. Epub 2020 Jul 8.

Department of Pediatric Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, 1678 Dong Fang Road, Shanghai 200127, China.

Stem-cell based differentiation for disease modeling offers great value to explore the molecular and functional underpinnings driving many types of cardiomyopathy and congenital heart diseases. Nevertheless, one major caveat in the application of differentiation of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) involves the immature phenotype of the CMs. Most of the existing methods need complex apparatus and require laborious procedures in order to monitor the cardiac differentiation/maturation process and often result in cell death. Here we developed an intrinsic color sensing system utilizing a microgroove structural color methacrylated gelatin film, which allows us to monitor the cardiac differentiation process of hiPSC-derived cardiac progenitor cells in real time. Subsequently this system can be employed as an assay system to live monitor induced functional changes on hiPSC-CMs stemming from drug treatment, the effects of which are simply revealed through color diversity. Our research shows that early intervention of cardiac differentiation through simple physical cues can enhance cardiac differentiation and maturation to some extent. Our system also simplifies the previous complex experimental processes for evaluating the physiological effects of successful differentiation and drug treatment and lays a solid foundation for future transformational applications.
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http://dx.doi.org/10.1021/acsnano.0c01745DOI Listing
July 2020

Cardiac progenitors and paracrine mediators in cardiogenesis and heart regeneration.

Semin Cell Dev Biol 2020 04 18;100:29-51. Epub 2019 Dec 18.

Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden; Department of Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden. Electronic address:

The mammalian hearts have the least regenerative capabilities among tissues and organs. As such, heart regeneration has been and continues to be the ultimate goal in the treatment against acquired and congenital heart diseases. Uncovering such a long-awaited therapy is still extremely challenging in the current settings. On the other hand, this desperate need for effective heart regeneration has developed various forms of modern biotechnologies in recent years. These involve the transplantation of pluripotent stem cell-derived cardiac progenitors or cardiomyocytes generated in vitro and novel biochemical molecules along with tissue engineering platforms. Such newly generated technologies and approaches have been shown to effectively proliferate cardiomyocytes and promote heart repair in the diseased settings, albeit mainly preclinically. These novel tools and medicines give somehow credence to breaking down the barriers associated with re-building heart muscle. However, in order to maximize efficacy and achieve better clinical outcomes through these cell-based and/or cell-free therapies, it is crucial to understand more deeply the developmental cellular hierarchies/paths and molecular mechanisms in normal or pathological cardiogenesis. Indeed, the morphogenetic process of mammalian cardiac development is highly complex and spatiotemporally regulated by various types of cardiac progenitors and their paracrine mediators. Here we discuss the most recent knowledge and findings in cardiac progenitor cell biology and the major cardiogenic paracrine mediators in the settings of cardiogenesis, congenital heart disease, and heart regeneration.
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http://dx.doi.org/10.1016/j.semcdb.2019.10.011DOI Listing
April 2020

Cell-mediated delivery of VEGF modified mRNA enhances blood vessel regeneration and ameliorates murine critical limb ischemia.

J Control Release 2019 09 16;310:103-114. Epub 2019 Aug 16.

Department of Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden. Electronic address:

Synthetic chemically modified mRNAs (modRNA) encoding vascular endothelial growth factor (VEGF) represents an alternative to gene therapy for the treatment of ischemic cardiovascular injuries. However, novel delivery approaches of modRNA are needed to improve therapeutic efficacy in the diseased setting. We hypothesized that cell-mediated modRNA delivery may enhance the in vivo expression kinetics of VEGF protein thus promoting more potent angiogenic effects. Here, we employed skin fibroblasts as a "proof of concept" to probe the therapeutic potential of a cell-mediated mRNA delivery system in a murine model of critical limb ischemia (CLI). We show that fibroblasts pre-treated with VEGF modRNA have the potential to fully salvage ischemic limbs. Using detailed molecular analysis we reveal that a fibroblast-VEGF modRNA combinatorial treatment significantly reduced tissue necrosis and dramatically improved vascular densities in CLI-injured limbs when compared to control and vehicle groups. Furthermore, fibroblast-delivered VEGF modRNA treatment increased the presence of Pax7 satellite cells, indicating a possible correlation between VEGF and satellite cell activity. Our study is the first to demonstrate that a cell-mediated modRNA therapy could be an alternative advanced strategy for cardiovascular diseases.
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http://dx.doi.org/10.1016/j.jconrel.2019.08.014DOI Listing
September 2019

Tissue-engineered trachea from a 3D-printed scaffold enhances whole-segment tracheal repair in a goat model.

J Tissue Eng Regen Med 2019 04 1;13(4):694-703. Epub 2019 Apr 1.

Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.

Traditional treatment therapies for tracheal stenosis often cause severe post-operative complications. To solve the current difficulties, novel and more suitable long-term treatments are needed. A whole-segment tissue-engineered trachea (TET) representing the native goat trachea was 3D printed using a poly(caprolactone) (PCL) scaffold engineered with autologous auricular cartilage cells. The TET underwent mechanical analysis followed by in vivo implantations in order to evaluate the clinical feasibility and potential. The 3D-printed scaffolds were successfully cellularized, as observed by scanning electron microscopy. Mechanical force compression studies revealed that both PCL scaffolds and TETs have a more robust compressive strength than does the native trachea. In vivo implantation of TETs in the experimental group resulted in significantly higher mean post-operative survival times, 65.00 ± 24.01 days (n = 5), when compared with the control group, which received autologous trachea grafts, 17.60 ± 3.51 days (n = 5). Although tracheal narrowing was confirmed by bronchoscopy and computed tomography examination in the experimental group, tissue necrosis was only observed in the control group. Furthermore, an encouraging epithelial-like tissue formation was observed in the TETs after transplantation. This large animal study provides potential preclinical evidence around the employment of an orthotopic transplantation of a whole 3D-printed TET.
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http://dx.doi.org/10.1002/term.2828DOI Listing
April 2019

Population and Single-Cell Analysis of Human Cardiogenesis Reveals Unique LGR5 Ventricular Progenitors in Embryonic Outflow Tract.

Dev Cell 2019 02 31;48(4):475-490.e7. Epub 2019 Jan 31.

Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm 171 77, Sweden; Department of Medicine-Cardiology, Karolinska Institutet, Stockholm 141 86, Sweden. Electronic address:

The morphogenetic process of mammalian cardiac development is complex and highly regulated spatiotemporally by multipotent cardiac stem/progenitor cells (CPCs). Mouse studies have been informative for understanding mammalian cardiogenesis; however, similar insights have been poorly established in humans. Here, we report comprehensive gene expression profiles of human cardiac derivatives from multipotent CPCs to intermediates and mature cardiac cells by population and single-cell RNA-seq using human embryonic stem cell-derived and embryonic/fetal heart-derived cardiac cells micro-dissected from specific heart compartments. Importantly, we discover a uniquely human subset of cono-ventricular region-specific CPCs, marked by LGR5. At 4 to 5 weeks of fetal age, the LGR5 population appears to emerge specifically in the proximal outflow tract of human embryonic hearts and thereafter promotes cardiac development and alignment through expansion of the ISL1TNNT2 intermediates. The current study contributes to a deeper understanding of human cardiogenesis, which may uncover the putative origins of certain human congenital cardiac malformations.
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http://dx.doi.org/10.1016/j.devcel.2019.01.005DOI Listing
February 2019

Biocompatible, Purified mRNA Improves Cardiac Function after Intracardiac Injection 1 Week Post-myocardial Infarction in Swine.

Mol Ther Methods Clin Dev 2018 Jun 10;9:330-346. Epub 2018 Apr 10.

Innovative Medicines and Early Development Biotech Unit, Cardiovascular, Renal and Metabolic Diseases, AstraZeneca, Mölndal 431 83, Sweden.

mRNA can direct dose-dependent protein expression in cardiac muscle without genome integration, but to date has not been shown to improve cardiac function in a safe, clinically applicable way. Herein, we report that a purified and optimized mRNA in a biocompatible citrate-saline formulation is tissue specific, long acting, and does not stimulate an immune response. In small- and large-animal, permanent occlusion myocardial infarction models, mRNA improves systolic ventricular function and limits myocardial damage. Following a single administration a week post-infarction in mini pigs, left ventricular ejection fraction, inotropy, and ventricular compliance improved, border zone arteriolar and capillary density increased, and myocardial fibrosis decreased at 2 months post-treatment. Purified mRNA establishes the feasibility of improving cardiac function in the sub-acute therapeutic window and may represent a new class of therapies for ischemic injury.
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http://dx.doi.org/10.1016/j.omtm.2018.04.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6054703PMC
June 2018

Cardiac Progenitor Cells in Basic Biology and Regenerative Medicine.

Stem Cells Int 2018 5;2018:8283648. Epub 2018 Feb 5.

Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden.

Major cardiovascular events including myocardial infarction (MI) continue to dominate morbidity rates in the developed world. Although multiple device therapies and various pharmacological agents have been shown to improve patient care and reduce mortality rates, clinicians and researchers alike still lack a true panacea to regenerate damaged cardiac tissue. Over the previous two to three decades, cardiovascular stem cell therapies have held great promise. Several stem cell-based approaches have now been shown to improve ventricular function and are documented in preclinical animal models as well as phase I and phase II clinical trials. More recently, the cardiac progenitor cell has begun to gain momentum as an ideal candidate for stem cell therapy in heart disease. Here, we will highlight the most recent advances in cardiac stem/progenitor cell biology in regard to both the basics and applied settings.
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http://dx.doi.org/10.1155/2018/8283648DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832196PMC
February 2018

Tissue-engineered trachea from a 3D-printed scaffold enhances whole-segment tracheal repair.

Sci Rep 2017 07 12;7(1):5246. Epub 2017 Jul 12.

Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, 1678 Dong Fang Road, Shanghai, 200127, China.

Long segmental repair of trachea stenosis is an intractable condition in the clinic. The reconstruction of an artificial substitute by tissue engineering is a promising approach to solve this unmet clinical need. 3D printing technology provides an infinite possibility for engineering a trachea. Here, we 3D printed a biodegradable reticular polycaprolactone (PCL) scaffold with similar morphology to the whole segment of rabbits' native trachea. The 3D-printed scaffold was suspended in culture with chondrocytes for 2 (Group I) or 4 (Group II) weeks, respectively. This in vitro suspension produced a more successful reconstruction of a tissue-engineered trachea (TET), which enhanced the overall support function of the replaced tracheal segment. After implantation of the chondrocyte-treated scaffold into the subcutaneous tissue of nude mice, the TET presented properties of mature cartilage tissue. To further evaluate the feasibility of repairing whole segment tracheal defects, replacement surgery of rabbits' native trachea by TET was performed. Following postoperative care, mean survival time in Group I was 14.38 ± 5.42 days, and in Group II was 22.58 ± 16.10 days, with the longest survival time being 10 weeks in Group II. In conclusion, we demonstrate the feasibility of repairing whole segment tracheal defects with 3D printed TET.
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http://dx.doi.org/10.1038/s41598-017-05518-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507982PMC
July 2017

Expansion of cardiac progenitors from reprogrammed fibroblasts as potential novel cardiovascular therapy.

Stem Cell Investig 2016 5;3:34. Epub 2016 Aug 5.

1 Department of Cell and Molecular Biology, 2 Department of Medicine-Cardiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.

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http://dx.doi.org/10.21037/sci.2016.07.06DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981704PMC
September 2016

miR-128 regulates non-myocyte hyperplasia, deposition of extracellular matrix and Islet1 expression during newt cardiac regeneration.

Dev Biol 2013 Nov 20;383(2):253-63. Epub 2013 Sep 20.

Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, Svante Arrheniusväg 20C, Stockholm 10691, Sweden.

Cardiovascular disease is a global scourge to society, with novel therapeutic approaches required in order to alleviate the suffering caused by sustained cardiac damage. MicroRNAs (miRNAs) are being touted as one such approach in the fight against heart disease, acting as possible post-transcriptional molecular triggers responsible for invoking cardiac regeneration. To further ones understanding of miRNAs and cardiac regeneration, it is prudent to learn from organisms that can intrinsically regenerate their hearts following injury. Using the red-spotted newt, an adult chordate capable of cardiac regeneration, we decided to delve deeper into the role miRNAs play during this process. RNA isolated from regenerating newt heart samples, was used in a microarray screen, to identify significantly expressed candidate miRNAs during newt cardiac regeneration. We performed quantitative qPCR analysis on several conserved miRNAs and found one in particular, miR-128, to be significantly elevated when cardiac hyperplasia is at its peak following injury. In-situ hybridisation techniques revealed a localised expression pattern for miR-128 in the cardiomyocytes and non-cardiomyocytes in close proximity to the regeneration zone and in vivo knockdown studies revealed a regulatory role for miR-128 in proliferating non-cardiomyocyte populations and extracellular matrix deposition. Finally, 3'UTR reporter assays revealed Islet1 as a biological target for miR-128, which was confirmed further through in vivo Islet1 transcriptional and translational expression analysis in regenerating newt hearts. From these studies we conclude that miR-128 regulates both cardiac hyperplasia and Islet1 expression during newt heart regeneration and that this information could be translated into future mammalian cardiac studies.
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http://dx.doi.org/10.1016/j.ydbio.2013.09.011DOI Listing
November 2013

ADAR-related activation of adenosine-to-inosine RNA editing during regeneration.

Stem Cells Dev 2013 Aug 3;22(16):2254-67. Epub 2013 May 3.

Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.

Urodele amphibians possess an amazing regenerative capacity that requires the activation of cellular plasticity in differentiated cells and progenitor/stem cells. Many aspects of regeneration in Urodele amphibians recapitulate development, making it unlikely that gene regulatory pathways which are essential for development are mutually exclusive from those necessary for regeneration. One such post-transcriptional gene regulatory pathway, which has been previously shown to be essential for functional metazoan development, is RNA editing. RNA editing catalyses discrete nucleotide changes in RNA transcripts, creating a molecular diversity that could create an enticing connection to the activated cellular plasticity found in newts during regeneration. To assess whether RNA editing occurs during regeneration, we demonstrated that GABRA3 and ADAR2 mRNA transcripts are edited in uninjured and regenerating tissues. Full open-reading frame sequences for ADAR1 and ADAR2, two enzymes responsible for adenosine-to-inosine RNA editing, were cloned from newt brain cDNA and exhibited a strong resemblance to ADAR (adenosine deaminase, RNA-specific) enzymes discovered in mammals. We demonstrated that ADAR1 and ADAR2 mRNA expression levels are differentially expressed during different phases of regeneration in multiple tissues, whereas protein expression levels remain unaltered. In addition, we have characterized a fascinating nucleocytoplasmic shuttling of ADAR1 in a variety of different cell types during regeneration, which could provide a mechanism for controlling RNA editing, without altering translational output of the editing enzyme. The link between RNA editing and regeneration provides further insights into how lower organisms, such as the newt, can activate essential molecular pathways via the discrete alteration of RNA sequences.
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http://dx.doi.org/10.1089/scd.2013.0104DOI Listing
August 2013

Recapitulation of developmental cardiogenesis governs the morphological and functional regeneration of adult newt hearts following injury.

Dev Biol 2011 Jun 30;354(1):67-76. Epub 2011 Mar 30.

Molecular Biology and Functional Genomics, Stockholm University, Svante Arrheniusväg 20C, Stockholm, Sweden.

Urodele amphibians, like the newt, are the "champions of regeneration" as they are able to regenerate many body parts and tissues. Previous experiments, however, have suggested that the newt heart has only a limited regeneration capacity, similar to the human heart. Using a novel, reproducible ventricular resection model, we show for the first time that adult newt hearts can fully regenerate without any evidence of scarring. This process is governed by increased proliferation and the up-regulation of cardiac transcription factors normally expressed during developmental cardiogenesis. Furthermore, we are able to identify cells within the newly regenerated regions of the myocardium that express the LIM-homeodomain protein Islet1 and GATA4, transcription factors found in cardiac progenitors. Information acquired from using the newt as a model organism may help to shed light on the regeneration deficits demonstrated in damaged human hearts.
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http://dx.doi.org/10.1016/j.ydbio.2011.03.021DOI Listing
June 2011
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