Wolfram H Zimmermann

• Medical Doctor
• Managing Director at Universitätsmedizin Göttingen

Skeletal muscle microtissues are engineered to develop therapies for restoring muscle function in patients. However, optimal electrical field stimulation (EFS) parameters to evaluate the function of muscle microtissues remain unestablished. This study reports a protocol to optimize EFS parameters for eliciting contractile force of muscle microtissu...

Cardiomyocytes can be implanted to remuscularize the failing heart1, 2, 3, 4, 5, 6–7. Challenges include sufficient cardiomyocyte retention for a sustainable therapeutic impact without intolerable side effects, such as arrhythmia and tumour growth. We investigated the hypothesis that epicardial engineered heart muscle (EHM) allografts from induced...

Heart failure (HF) remains a leading cause of mortality, responsible for 13% of all deaths worldwide. The prognosis for patients with HF is poor, with only a 50% survival rate within 5 years. A major challenge of ischaemia-driven HF is the loss of cardiomyocytes, compounded by the minimal regenerative capacity of the adult heart. To date, replaceme...

Gene variants in LZTR1 are implicated to cause Noonan syndrome associated with a severe and early-onset hypertrophic cardiomyopathy. Mechanistically, LZTR1 deficiency results in accumulation of RAS GTPases and, as a consequence, in RAS-MAPK signaling hyperactivity, thereby causing the Noonan syndrome-associated phenotype. Despite its epidemiologica...

Force generation is an essential property of skeletal muscle models in vitro. We describe a versatile 1-step procedure to direct undifferentiated human pluripotent stem cells (PSCs) into contractile skeletal muscle organoids (SMOs). Our protocol provides detailed steps for 3D casting of PSCs using either collagen-I/Matrigel- or fibrin/Geltrex-based...

Arrhythmogenic cardiomyopathy is a severe cardiac disorder characterized by lethal arrhythmias and sudden cardiac death, with currently no effective treatment. Plakophilin 2 ( PKP2 ) is the most frequently affected gene. Here we show that adeno-associated virus (AAV)-mediated delivery of PKP2 in PKP2 c.2013delC/WT induced pluripotent stem cell-deri...

4D printing recently emerges as an exciting evolution of conventional 3D printing, where a printed construct can quickly transform in response to a specific stimulus to switch between a temporary variable state and an original state. In this work, a photocrosslinkable polyethylene–glycol polyurethane ink is synthesized for light‐assisted 4D printin...

Background and aims: Atrial fibrillation (AF) is associated with tachycardia-induced cellular electrophysiology alterations which promote AF chronification and treatment resistance. Development of novel antiarrhythmic therapies is hampered by the absence of scalable experimental human models that reflect AF-associated electrical remodelling. There...

Cardiac autonomic neurons control cardiac contractility. Dysregulation of the autonomic nervous system can lead to sympathetic overdrive resulting in heart failure and an increased incidence of fatal arrhythmias. Here, we introduce innervated engineered human myocardium (iEHM), a novel model of neuro-cardiac junctions, constructed by fusion of a bi...

Background: Atrial fibrillation (AF) is the most common clinically reported arrhythmia. It is associated with electrophysiological and structural alterations that promote the maintenance of the disease. The limited longevity of human cardiac samples has historically restricted mechanistic investigation into these remodeling processes of human atria...

Background: The human heart displays limited potential to recover from injury. Delta-like non-canonical Notch ligand-1 ( DLK1 ) is an imprinted gene strongly expressed during embryo-fetal development. Expression in postnatal organs is low but re-expression commonly occurs in regenerative organs after injury. We hypothesized that enhancing DLK1 expr...

The German Centre for Cardiovascular Research (DZHK) is one of the German Centres for Health Research and aims to conduct early and guideline-relevant studies to develop new therapies and diagnostics that impact the lives of people with cardiovascular disease. Therefore, DZHK members designed a collaboratively organised and integrated research plat...

Noonan syndrome patients harboring causative variants in LZTR1 are particularly at risk to develop severe and early-onset hypertrophic cardiomyopathy. However, the underling disease mechanisms of LZTR1 missense variants driving the cardiac pathology are poorly understood. Hence, therapeutic options for Noonan syndrome patients are limited. In this...

Duchenne muscular dystrophy (DMD) represents the most common inherited muscular disease, where increasing muscle weakness leads to loss of ambulation and premature death. DMD is caused by mutations in the dystrophin gene, and is known to reduce the contractile capacity of muscle tissue both in vivo, and also in reconstituted systems in vitro. Howev...

Background: Human pluripotent stem cell-derived muscle models show great potential for translational research. Here, we describe developmentally inspired methods for the derivation of skeletal muscle cells and their utility in skeletal muscle tissue engineering with the aim to model skeletal muscle regeneration and dystrophy in vitro. Methods: K...

Motivated by a high demand, the research interest in personalized artificial tissues is steadily increasing. Combining knowledge of additive manufacturing and tissue engineering, the research field of 3D bioprinting emerged. This work presents a six-degree-of-freedom mechanically actuated extrusion bioprinter within a sterile working environment. T...

Tissue engineering with human cardiac fibroblasts (CF) allows identifying novel mechanisms and anti-fibrotic drugs in the context of cardiac fibrosis. However, substantial knowledge on the influences of the used materials and tissue geometries on tissue properties and cell phenotypes is necessary to be able to choose an appropriate model for a spec...

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 813716. Background RNA modifications affect gene expression through the regulation of...

A resorbable closed-loop sensor-actuator implant can temporarily control heart rate

Engineered heart muscle (EHM) can be implanted epicardially to remuscularize the failing heart. In case of a severely scarred ventricle, excision of scar followed by transmural heart wall replacement may be a more desirable application. Accordingly, we tested the hypothesis that allograft (rat) and xenograft (human) EHM can also be administered as...

The aim of CRC 1002 “Modulatory units in heart failure” is to identify new diagnostic and therapeutic strategies in heart failure to further develop them up to application on patients. New diagnostic and therapeutic principles will be tested in first-in-man clinical studies funded by the German Center for Cardiovascular Research (DZHK). Examples of...

Different engineered heart muscle formats have been developed for applications in disease modeling, drug screening, and heart repair. The advantage of 3D engineered versus 2D monolayer and 3D aggregate cardiomyocyte cultures is a clearly advanced degree of maturation, which in many aspects resembles the postnatal rather than the embryonic or fetal...

Introduction: Heterozygous truncating variants in TTN (TTNtv) coding for titin cause dilated cardiomyopathy (DCM) but the underlying pathomechanisms are unclear and disease management remains uncertain. Here, we aim to elucidate the key pathomechanisms of TTNtv-DCM. Hypothesis: Stable expression of truncated titin proteins and titin haploinsufficie...

Heterozygous truncating variants in TTN (TTNtv), the gene coding for titin, cause dilated cardiomyopathy (DCM), but the underlying pathomechanisms are unclear and disease management remains uncertain. Truncated titin proteins have not yet been considered as a contributor to disease development. Here, we studied myocardial tissues from nonfailing do...

This paper aims to provide an important update on the recent preclinical and clinical trials using cell therapy strategies and engineered heart tissues for the treatment of postinfarction left ventricular remodeling and heart failure. In addition to the authors’ own works and opinions on the roadblocks of the field, they discuss novel approaches fo...

Background Imbalanced transcriptional networks characterize cardiomyocyte stress and result in cardiac remodelling. We hypothesize that re-establishing homeostatic gene networks in cardiomyocytes will prevent further tissue damage. To tackle this challenge, we applied CRISPR-based endogenous gene activation (CRISPRa) in vivo and in vitro. Methods...

While some individuals age without pathological memory impairments, others develop age-associated cognitive diseases. Since changes in cognitive function develop slowly over time in these patients, they are often diagnosed at an advanced stage of molecular pathology, a time point when causative treatments fail. Thus, there is great need for the ide...

CRISPR/Cas9 technology based on nuclease inactive dCas9 and fused to the heterotrimeric VPR transcriptional activator is a powerful tool to enhance endogenous transcription by targeting defined genomic loci. We generated homozygous human induced pluripotent stem cell (hiPSC) lines carrying dCas9 fused to VPR along with a WPRE element at the AAVS1 l...

Transcriptional changes in cardiomyocytes drive heart failure progression, however, precise control over endogenous gene expression remains challenging. The expression of Krueppel-like factor 15 ( KLF15 ), an evolutionary conserved nuclear and cardiomyocyte specific inhibitor of WNT/CTNNB1 signalling in the heart, is lost upon cardiac remodelling,...

Kittana N, Assali M, Zimmermann WH, et al. Int J Nanomedicine. 2021;16:989–1000. The authors have advised that the Funding statement on pages 997 and 998 is incorrect. The correct funding statement is: Funding NK and MA: The project was kindly funded and supported by the Palestinian Ministry of Higher Education (fund ID number ANNU-MoHE-1819-Sc010)...

Human pluripotent stem cells (hPSCs) hold great promise for applications in cell therapy and drug screening in the cardiovascular field. Bone morphogenetic protein 4 (BMP4) is key for early cardiac mesoderm induction in hPSC and subsequent cardiomyocyte derivation. Small‐molecular BMP4 mimetics may help to standardize cardiomyocyte derivation from...

Fibroblasts are phenotypically highly dynamic cells, which quickly transdifferentiate into myofibroblasts in response to biochemical and biomechanical stimuli. The current understanding of fibrotic processes, including cardiac fibrosis, remains poor, which hampers the development of new anti-fibrotic therapies. Controllable and reliable human model...

Human pluripotent stem cell derived muscle models show great potential for translational research. Here, we describe developmentally inspired methods for derivation of skeletal muscle cells and their utility in three-dimensional skeletal muscle organoid formation as well as skeletal muscle tissue engineering. Key steps include the directed differen...

Using nuclease-deficient dead (d)Cas9 without enzymatic activity fused to transcriptional inhibitors (CRISPRi) allows for transcriptional interference and results in a powerful tool for the elucidation of developmental, homeostatic and disease mechanisms. We inserted dCas9KRAB (CRISPRi) cassette into the AAVS1 locus of hiPSC lines, which resulted i...

Cardiac MRI in rhesus macaques, a species of major relevance for preclinical studies on biological therapies, requires artificial ventilation to realize breath holding. To overcome this limitation of standard cine MRI, the feasibility of Real-Time (RT) cardiac MRI has been tested in a cohort of ten adult rhesus macaques using a clinical MR-system....

The homeodomain transcription factor SHOX2 is involved in the development and function of the heart's primary pacemaker, the sinoatrial node (SAN), and has been associated with cardiac conduction-related diseases such as atrial fibrillation and sinus node dysfunction. To shed light on Shox2-dependent genetic processes involved in these diseases, we...

Aims: After a myocardial infarction, the adult human heart lacks sufficient regenerative capacity to restore lost tissue, leading to heart failure progression. Finding novel ways to reprogram adult cardiomyocytes into a regenerative state is a major therapeutic goal. The epicardium, the outermost layer of the heart, contributes cardiovascular cell...

Background Under certain conditions, the physiological repair of connective tissues might fail to restore the original structure and function. Optimized engineered connective tissues (ECTs) with biophysical properties adapted to the target tissue could be used as a substitution therapy. This study aimed to investigate the effect of ECT enforcement...

Stem cells such as mesenchymal stem cells (MSCs) enhance neurological recovery in preclinical stroke models by secreting extracellular vesicles (EVs). Since previous reports have focused on the application of MSC-EVs only, the role of the most suitable host cell for EV enrichment and preclinical stroke treatment remains elusive. The present study a...

Background Great expectations have been set around the clinical potential of regenerative and reparative medicine in the treatment of cardiovascular diseases (i.e., in particular heart failure [HF]). Initial excitement, spurred by encouraging preclinical data, resulted in a rapid translation into clinical research. The sobering outcome of the resul...

Classical drug development is compromised by considerable clinical failure of promising drug candidates after decades of costly preclinical work. Failure can be because of previously unrecognized safety concerns or more commonly lack of clinical efficacy. Classical drug discovery and safety pharmacology programs rely heavily on well-established in...

Background Pathological remodeling of the myocardium has long been known to involve oxidant signaling, but so far, strategies using systemic anti-oxidants have generally failed to prevent it. Aquaporins are a family of transmembrane water channels with thirteen isoforms currently known. Some isoforms have been implicated in oxidant signaling. AQP1...

Background/Purpose Dilated cardiomyopathy (DCM) is characterized by left ventricular dilation and contractile dysfunction. Fibrosis is one major phenotypic result in DCM, pointing to the contribution of both, cardiomyocytes (CM) and cardiac fibroblasts (cFB) to DCM. The molecular basis of most DCM cases remains unknown. Nevertheless, it is known th...

Pathological remodeling of the myocardium has long been known to involve oxidant signaling, but strategies using systemic antioxidants have generally failed to prevent it. We sought to identify key regulators of oxidant-mediated cardiac hypertrophy amenable to targeted pharmacological therapy. Specific isoforms of the aquaporin water channels have...

Aims: Arrhythmias and sudden cardiac death (SCD) occur commonly in patients with heart failure. We found T-box 5 (TBX5) dysregulated in ventricular myocardium from heart failure patients and thus we hypothesized that TBX5 reduction contributes to arrhythmia development in these patients. To understand the underlying mechanisms, we aimed to reveal...

Brain organoids are promising tools for disease modeling and drug development. For proper neuronal network formation excitatory and inhibitory neurons as well as glia need to co-develop. Here, we report the directed self-organization of human induced pluripotent stem cells in a collagen hydrogel towards a highly interconnected neuronal network at a...

Background: Noonan syndrome (NS) is a multisystemic developmental disorder characterized by common, clinically variable symptoms, such as typical facial dysmorphisms, short stature, developmental delay, intellectual disability as well as cardiac hypertrophy. The underlying mechanism is a gain-of-function of the RAS-mitogen-activated protein kinase...

Here we present a new directed differentiation and maturation protocol to generate Bioengineered Neuronal Organoids (BENOs) comprised of complex networks of inhibitory and excitatory neurons as well as supporting glial cells (astrocytes and myelinating oligodendrocytes).

This protocol describes a robust method for the generation of engineered human myocardium (EHM) from pluripotent stem cells (PSCs) in a multi-well plate under defined, serum-free conditions. By parallel culture of up to 48 EHM in one plate, contractile heart muscle can be obtained to serve numerous applications, including drug screening and disease...

Non-human primates (NHP) are important surrogate models for late preclinical development of advanced therapy medicinal products (ATMPs), including induced pluripotent stem cell (iPSC)-based therapies, which are also under development for heart failure repair. For effective heart repair by remuscularization, large numbers of cardiomyocytes are requi...

Die Volkskrankheit Herzmuskelschwäche ist vor dem Hintergrund des demographischen Wandels nicht nur eine medizinische, sondern auch zunehmend eine sozioökonomische und damit gesellschaftspolitische Herausforderung. Die hohe Sterblichkeit und die stark eingeschränkte Lebensqualität von Patienten mit Herzmuskelschwäche wird durch aktuelle Therapiemaß...

Introduction: This report summarizes and discusses talks delivered at an educational course offered during the 2019 Annual Meeting of the Safety Pharmacology Society on advanced therapy medicinal products (ATMPs) and cell gene therapeutic products (CGTPs). Areas covered: ATMPs and CGTPs comprise gene and cell therapy medicinal products, tissue-engi...

Abstract: Understanding the processes involved in cardiac fibrosis is essential for the development of suitable anti-fibrotic drugs. The complexity of the intercellular communication in the heart and the phenotypic instability of isolated cardiac fibroblasts represent, however, two major hurdles in this research area. Therefore, we developed an eng...

The lack of regenerative therapies for the treatment of degenerative diseases, such as heart failure, motivates the search for cell therapeutics. From a technical point of view, cell-based heart repair is approached from two angles: (1) by injection of cells and (2) by epicardial implantation of tissue engineered constructs. The choice of cells dep...

The sarcomeric troponin-tropomyosin complex is a critical mediator of excitation-contraction coupling, sarcomeric stability and force generation. We previously reported that induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from patients with a dilated cardiomyopathy (DCM) mutation, troponin T (TnT)-R173W, display sarcomere protein mi...

Cardiac tissue engineering is evolving rapidly towards a stage of clinical testing. First tissue engineered non-myocyte containing patches have already been tested clinically. The next generation of cardiomyocyte-containing, contractile allografts will follow soon. Here we provide an overview of the state-of-the-art in human heart muscle engineerin...

Rationale: Genome editing by CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 is evolving rapidly. Recently, second-generation CRISPR/Cas9 activation systems based on nuclease inactive dead (d)Cas9 fused to transcriptional transactivation domains were developed for directing specific guide (g)RNAs to regulatory regions of an...

Abstract Satellite cells reside in defined niches and are activated upon skeletal muscle injury to facilitate regeneration. Mechanistic studies of skeletal muscle regeneration are hampered by the inability to faithfully simulate satellite cell biology in vitro. We sought to overcome this limitation by developing tissue engineered skeletal muscle (E...

Background Among rare channelopathies BrS patients are at high risk of sudden cardiac death (SCD). SCN5A mutations are found in a quarter of patients. Other rare gene mutations including SCN1B have been implicated to BrS. Studying the human cellular phenotype of BrS associated with rare gene mutation remains lacking. Objectives We sought to study...

Deterioration or inborn malformations of the cardiac conduction system (CCS) interfere with proper impulse propagation in the heart and may lead to sudden cardiac death or heart failure. Patients afflicted with arrhythmia depend on antiarrhythmic medication or invasive therapy, such as pacemaker implantation. An ideal way to treat these patients wo...

Background: The combination of cardiomyocyte (CM) and vascular cell (VC) fetal reprogramming upon stress culminates in end-stage heart failure (HF) by mechanisms that are not fully understood. Previous studies suggest KLF15 as a key regulator of CM hypertrophy. Objectives: This study aimed to characterize the impact of KLF15-dependent cardiac tr...

Background Abnormal activity of muscarinic receptor (M-receptor) activated potassium current (IK,ACh) has been suggested as a potential atrial-specific drug target for antiarrhythmic therapy in patients with atrial fibrillation (AF). Recent work suggests that atrial myocytes derived from human induced pluripotent stem cells (iPSC-CM) hold great pot...

Methods for cardiac tissue engineering and application in experiments are core technologies developed at the Institute of Pharmacology and Toxicology in Göttingen. As is the case in many academic research laboratories data capture and documentation may be improved to latest methods of digital research. A comprehensive information system infrastruct...

Cardiac remodelling is accompanied by silencing of genes necessary for cardiac homeostasis including Krüppel-like factor 15 ( Klf15 ), an anti-hypertrophic factor. Due to a lack of tools for gene activation, we aim to adapt a CRISPR-based approach for gene expression control for mammalian cardiomyocytes. We generated a transgenic mouse model (TG) e...

Integrative biochemical and omic-based approaches have refined our understanding of how cells integrate the Wnt signal at the chromatin level to yield specific cellular responses. However, this aspect remains unexplored in the heart. Since Wnt/β-catenin signaling activation is a hallmark in pathological cardiac remodeling, we aimed to characterize...

Background: Familial atrial septal defect (ASD) has previously been attributed primarily to mutations in cardiac transcription factors. Here, we report a large, multi-generational family (78 members) with ASD combined with a late-onset dilated cardiomyopathy and further characterize the consequences of mutant α-actin. Methods: We combined a geno...

Cardiac fibrosis is a hallmark of heart failure for which there is no effective pharmacological therapy. By genetic modification and in vivo inhibitor approaches it was suggested that the Rho-associated kinases (ROCK1 and ROCK2) are involved in pro-fibrotic signalling in cardiac fibroblasts and that they may serve as targets for anti-fibrotic thera...

Aims: Brugada syndrome (BrS) is associated with a pronounced risk to develop sudden cardiac death (SCD). Up to 21% of patients are related to mutations in SCN5A. Studies identified SCN10A as a contributor of BrS. However, the investigation of the human cellular phenotype of BrS in the presence of SCN10A mutations remains lacking. The objective of...

Cardiac tissue engineering provides unique opportunities for cardiovascular disease modeling, drug testing, and regenerative medicine applications. To recapitulate human heart tissue, we combined human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with a chitosan-enhanced extracellular-matrix (ECM) hydrogel, derived from decellul...

Abstract: Our understanding of processes being involved in cardiac fibrosis is still poor, which hampers the development of new anti-fibrotic therapies. Controllable and reliable model systems are needed, which allow us to improve our understanding in cardiac fibroblasts (CF) biology and facilitate drug screening. Engineered connective tissues (ECT...

Abstract Acute myocardial infarction (MI) evokes a systemic inflammatory response and locally the degradation of the necrotic tissue, followed by scar formation. The mechanisms for containment of the infarct zone are not studied well. The study aimed to examine the response of healthy cardiomyocytes to serum of patients with myocardial infarction....

Redox signaling affects all aspects of cardiac function and homeostasis. With the development of genetically encoded fluorescent redox sensors, novel tools for the optogenetic investigation of redox signaling have emerged. Here, we sought to develop a human heart muscle model for in-tissue imaging of redox alterations. For this, we made use of (1)...

Short QT syndrome (SQTS) predisposes afflicted patients to sudden cardiac death. Until now only one drug (quinidine) has been shown to be effective in patients with SQTS type 1(SQTS1). The objective of this study was to use human‐induced pluripotent stem cell–derived cardiomyocytes (hiPSC‐CMs) from a patient with SQTS1 to search for potentially eff...