Nenad Bursac

Overview:

Bursac's research interests include: Stem cell, tissue engineering, and gene based therapies for heart and muscle regeneration; Cardiac electrophysiology and arrhythmias; Organ-on-chip and tissue engineering technologies for disease modeling and therapeutic screening; Small and large animal models of heart and muscle injury, disease, and regeneration.

The focus of my research is on application of pluripotent stem cells, tissue engineering, and gene therapy technologies for: 1) basic studies of striated muscle biology and disease in vitro and 2) regenerative therapies in small and large animal models in vivo. For in vitro studies, micropatterning of extracellular matrix proteins or protein hydrogels and 3D cell culture are used to engineer rodent and human striated muscle tissues that replicate the structure-function relationships present in healthy and diseased muscles. We use these models to separate and systematically study the roles of structural and genetic factors that contribute cardiac and skeletal muscle function and disease at multiple organizational levels, from single cells to tissues. Combining cardiac and skeletal muscle cells with primary or iPSC-derived non-muscle cells (endothelial cells, smooth muscle cells, immune system cells, neurons) allows us to generate more realistic models of healthy and diseased human tissues and utilize them to mechanistically study molecular and cellular processes of tissue injury, vascularization, innervation, electromechanical integration, fibrosis, and functional repair. Currently, in vitro models of Duchenne Muscular Dystrophy, Pompe disease, dyspherlinopathies, and various cardiomyopathies are studied in the lab. For in vivo studies, we employ rodent models of volumetric skeletal muscle loss, cardiotoxin and BaCl2 injury as well as myocardial infarction and transverse aortic constriction to study how cell, tissue engineering, and gene (viral) therapies can lead to safe and efficient tissue repair and regeneration. In large animal (porcine) models of myocardial injury and arrhythmias, we are exploring how human iPSC derived heart tissue patches and application of engineered ion channels can improve cardiac function and prevent heart failure or sudden cardiac death.

 

Positions:

Professor of Biomedical Engineering

Biomedical Engineering
Pratt School of Engineering

Associate Professor in Medicine

Medicine, Cardiology
School of Medicine

Professor in Cell Biology

Cell Biology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Co-Director of the Duke Regeneration Center

Regeneration Next Initiative
School of Medicine

Education:

B.S.E. 1994

University of Belgrade (Serbia)

Ph.D. 2000

Boston University

Grants:

Muscle-macrophage constructs for skeletal muscle repair

Administered By
Biomedical Engineering
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Engineering of Human Excitable Tissues from Unexcitable Cells

Administered By
Biomedical Engineering
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

In Vitro and In Situ Engineering of Fibroblasts for Cardiac Repair

Administered By
Biomedical Engineering
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Translational studies of GAA deficiency in bioengineered human muscle

Administered By
Biomedical Engineering
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Integrated Cellular and Tissue Engineering for Ischemic Heart Disease

Administered By
Biomedical Engineering
Awarded By
University of Alabama at Birmingham
Role
Principal Investigator
Start Date
End Date

Publications:

An enhancer-based gene-therapy strategy for spatiotemporal control of cargoes during tissue repair.

The efficacy and safety of gene-therapy strategies for indications like tissue damage hinge on precision; yet, current methods afford little spatial or temporal control of payload delivery. Here, we find that tissue-regeneration enhancer elements (TREEs) isolated from zebrafish can direct targeted, injury-associated gene expression from viral DNA vectors delivered systemically in small and large adult mammalian species. When employed in combination with CRISPR-based epigenome editing tools in mice, zebrafish TREEs stimulated or repressed the expression of endogenous genes after ischemic myocardial infarction. Intravenously delivered recombinant AAV vectors designed with a TREE to direct a constitutively active YAP factor boosted indicators of cardiac regeneration in mice and improved the function of the injured heart. Our findings establish the application of contextual enhancer elements as a potential therapeutic platform for spatiotemporally controlled tissue regeneration in mammals.
Authors
Yan, R; Cigliola, V; Oonk, KA; Petrover, Z; DeLuca, S; Wolfson, DW; Vekstein, A; Mendiola, MA; Devlin, G; Bishawi, M; Gemberling, MP; Sinha, T; Sargent, MA; York, AJ; Shakked, A; DeBenedittis, P; Wendell, DC; Ou, J; Kang, J; Goldman, JA; Baht, GS; Karra, R; Williams, AR; Bowles, DE; Asokan, A; Tzahor, E; Gersbach, CA; Molkentin, JD; Bursac, N; Black, BL; Poss, KD
MLA Citation
Yan, Ruorong, et al. “An enhancer-based gene-therapy strategy for spatiotemporal control of cargoes during tissue repair.Cell Stem Cell, vol. 30, no. 1, Jan. 2023, pp. 96-111.e6. Pubmed, doi:10.1016/j.stem.2022.11.012.
URI
https://scholars.duke.edu/individual/pub1560043
PMID
36516837
Source
pubmed
Published In
Cell Stem Cell
Volume
30
Published Date
Start Page
96
End Page
111.e6
DOI
10.1016/j.stem.2022.11.012

Meteorin-like is an injectable peptide that can enhance regeneration in aged muscle through immune-driven fibro/adipogenic progenitor signaling.

Pathologies associated with sarcopenia include decline in muscular strength, lean mass and regenerative capacity. Despite the substantial impact on quality of life, no pharmacological therapeutics are available to counteract the age-associated decline in functional capacity and/or, resilience. Evidence suggests immune-secreted cytokines can improve muscle regeneration, a strategy which we leverage in this study by rescuing the age-related deficiency in Meteorin-like through several in vivo add-back models. Notably, the intramuscular, peptide injection of recombinant METRNL was sufficient to improve muscle regeneration in aging. Using ex vivo media exchange and in vivo TNF inhibition, we demonstrate a mechanism of METRNL action during regeneration, showing it counteracts a pro-fibrotic gene program by triggering TNFα-induced apoptosis of fibro/adipogenic progenitor cells. These findings demonstrate therapeutic applications for METRNL to improve aged muscle, and show Fibro/Adipogenic Progenitors are viable therapeutic targets to counteract age-related loss in muscle resilience.
Authors
Lee, DE; McKay, LK; Bareja, A; Li, Y; Khodabukus, A; Bursac, N; Taylor, GA; Baht, GS; White, JP
MLA Citation
Lee, David E., et al. “Meteorin-like is an injectable peptide that can enhance regeneration in aged muscle through immune-driven fibro/adipogenic progenitor signaling.Nat Commun, vol. 13, no. 1, Dec. 2022, p. 7613. Pubmed, doi:10.1038/s41467-022-35390-3.
URI
https://scholars.duke.edu/individual/pub1558761
PMID
36494364
Source
pubmed
Published In
Nature Communications
Volume
13
Published Date
Start Page
7613
DOI
10.1038/s41467-022-35390-3

Targeted Delivery for Cardiac Regeneration: Comparison of Intra-coronary Infusion and Intra-myocardial Injection in Porcine Hearts.

BACKGROUND: The optimal delivery route to enhance effectiveness of regenerative therapeutics to the human heart is poorly understood. Direct intra-myocardial (IM) injection is the gold standard, however, it is relatively invasive. We thus compared targeted IM against less invasive, catheter-based intra-coronary (IC) delivery to porcine myocardium for the acute retention of nanoparticles using cardiac magnetic resonance (CMR) imaging and viral vector transduction using qPCR. METHODS: Ferumoxytol iron oxide (IO) nanoparticles (5 ml) were administered to Yorkshire swine (n = 13) by: (1) IM via thoracotomy, (2) catheter-based IC balloon-occlusion (BO) with infusion into the distal left anterior descending (LAD) coronary artery, (3) IC perforated side-wall (SW) infusion into the LAD, or (4) non-selective IC via left main (LM) coronary artery infusion. Hearts were harvested and imaged using at 3T whole-body MRI scanner. In separate Yorkshire swine (n = 13), an adeno-associated virus (AAV) vector was similarly delivered, tissue harvested 4-6 weeks later, and viral DNA quantified from predefined areas at risk (apical LV/RV) vs. not at risk in a potential mid-LAD infarct model. Results were analyzed using pairwise Student's t-test. RESULTS: IM delivery yielded the highest IO retention (16.0 ± 4.6% of left ventricular volume). Of the IC approaches, BO showed the highest IO retention (8.7 ± 2.2% vs. SW = 5.5 ± 4.9% and LM = 0%) and yielded consistent uptake in the porcine distal LAD territory, including the apical septum, LV, and RV. IM delivery was limited to the apex and anterior wall, without septal retention. For the AAV delivery, the BO was most efficient in the at risk territory (Risk: BO = 6.0 × 10-9, IM = 1.4 × 10-9, LM = 3.2 × 10-10 viral copies per μg genomic DNA) while all delivery routes were comparable in the non-risk territory (BO = 1.7 × 10-9, IM = 8.9 × 10-10, LM = 1.2 × 10-9). CONCLUSIONS: Direct IM injection has the highest local retention, while IC delivery with balloon occlusion and distal infusion is the most effective IC delivery technique to target therapeutics to a heart territory most in risk from an infarct.
Authors
Vekstein, AM; Wendell, DC; DeLuca, S; Yan, R; Chen, Y; Bishawi, M; Devlin, GW; Asokan, A; Poss, KD; Bowles, DE; Williams, AR; Bursac, N
MLA Citation
Vekstein, Andrew M., et al. “Targeted Delivery for Cardiac Regeneration: Comparison of Intra-coronary Infusion and Intra-myocardial Injection in Porcine Hearts.Front Cardiovasc Med, vol. 9, 2022, p. 833335. Pubmed, doi:10.3389/fcvm.2022.833335.
URI
https://scholars.duke.edu/individual/pub1511728
PMID
35224061
Source
pubmed
Published In
Frontiers in Cardiovascular Medicine
Volume
9
Published Date
Start Page
833335
DOI
10.3389/fcvm.2022.833335

Differential microRNA profiles of intramuscular and secreted extracellular vesicles in human tissue-engineered muscle.

Exercise affects the expression of microRNAs (miR/s) and muscle-derived extracellular vesicles (EVs). To evaluate sarcoplasmic and secreted miR expression in human skeletal muscle in response to exercise-mimetic contractile activity, we utilized a three-dimensional tissue-engineered model of human skeletal muscle ("myobundles"). Myobundles were subjected to three culture conditions: no electrical stimulation (CTL), chronic low frequency stimulation (CLFS), or intermittent high frequency stimulation (IHFS) for 7 days. RNA was isolated from myobundles and from extracellular vesicles (EVs) secreted by myobundles into culture media; miR abundance was analyzed by miRNA-sequencing. We used edgeR and a within-sample design to evaluate differential miR expression and Pearson correlation to evaluate correlations between myobundle and EV populations within treatments with statistical significance set at p < 0.05. Numerous miRs were differentially expressed between myobundles and EVs; 116 miRs were differentially expressed within CTL, 3 within CLFS, and 2 within IHFS. Additionally, 25 miRs were significantly correlated (18 in CTL, 5 in CLFS, 2 in IHFS) between myobundles and EVs. Electrical stimulation resulted in differential expression of 8 miRs in myobundles and only 1 miR in EVs. Several KEGG pathways, known to play a role in regulation of skeletal muscle, were enriched, with differentially overrepresented miRs between myobundle and EV populations identified using miEAA. Together, these results demonstrate that in vitro exercise-mimetic contractile activity of human engineered muscle affects both their expression of miRs and number of secreted EVs. These results also identify novel miRs of interest for future studies of the role of exercise in organ-organ interactions in vivo.
Authors
Vann, CG; Zhang, X; Khodabukus, A; Orenduff, MC; Chen, Y-H; Corcoran, DL; Truskey, GA; Bursac, N; Kraus, VB
MLA Citation
Vann, Christopher G., et al. “Differential microRNA profiles of intramuscular and secreted extracellular vesicles in human tissue-engineered muscle.Front Physiol, vol. 13, 2022, p. 937899. Pubmed, doi:10.3389/fphys.2022.937899.
URI
https://scholars.duke.edu/individual/pub1546729
PMID
36091396
Source
pubmed
Published In
Frontiers in Physiology
Volume
13
Published Date
Start Page
937899
DOI
10.3389/fphys.2022.937899

Translating musculoskeletal bioengineering into tissue regeneration therapies.

Musculoskeletal injuries and disorders are the leading cause of physical disability worldwide and a considerable socioeconomic burden. The lack of effective therapies has driven the development of novel bioengineering approaches that have recently started to gain clinical approvals. In this review, we first discuss the self-repair capacity of the musculoskeletal tissues and describe causes of musculoskeletal dysfunction. We then review the development of novel biomaterial, immunomodulatory, cellular, and gene therapies to treat musculoskeletal disorders. Last, we consider the recent regulatory changes and future areas of technological progress that can accelerate translation of these therapies to clinical practice.
Authors
Khodabukus, A; Guyer, T; Moore, AC; Stevens, MM; Guldberg, RE; Bursac, N
MLA Citation
Khodabukus, Alastair, et al. “Translating musculoskeletal bioengineering into tissue regeneration therapies.Science Translational Medicine, vol. 14, no. 666, Oct. 2022, p. eabn9074. Epmc, doi:10.1126/scitranslmed.abn9074.
URI
https://scholars.duke.edu/individual/pub1554263
PMID
36223445
Source
epmc
Published In
Science Translational Medicine
Volume
14
Published Date
Start Page
eabn9074
DOI
10.1126/scitranslmed.abn9074

Research Areas:

Action Potentials
Anisotropy
Arrhythmias, Cardiac
Biomedical Engineering
Bioreactors
Cardiomyopathies
Connexin 43
Electrophysiological Processes
Electrophysiology
Fibroblasts
HEK293 Cells
Hydrogels
Induced Pluripotent Stem Cells
Microtechnology
Muscle, Skeletal
Muscle, Striated
Myoblasts, Skeletal
Myocardial Infarction
Myocytes, Cardiac
Pluripotent Stem Cells
Regenerative Medicine
Satellite Cells, Skeletal Muscle
Stem Cell Transplantation
Stem Cells
Tissue Engineering
Tissue Scaffolds
Voltage-Sensitive Dye Imaging