Publications by authors named "Sean V Murphy"

39 Publications

A Rapid Crosslinkable Maleimide-Modified Hyaluronic Acid and Gelatin Hydrogel Delivery System for Regenerative Applications.

Gels 2021 Feb 1;7(1). Epub 2021 Feb 1.

Department of Biomedical Engineering, The Ohio State University, Fontana Labs., 140 W. 19th Ave, Columbus, OH 43210, USA.

Hydrogels have played a significant role in many applications of regenerative medicine and tissue engineering due to their versatile properties in realizing design and functional requirements. However, as bioengineered solutions are translated towards clinical application, new hurdles and subsequent material requirements can arise. For example, in applications such as cell encapsulation, drug delivery, and biofabrication, in a clinical setting, hydrogels benefit from being comprised of natural extracellular matrix-based materials, but with defined, controllable, and modular properties. Advantages for these clinical applications include ultraviolet light-free and rapid polymerization crosslinking kinetics, and a cell-friendly crosslinking environment that supports cell encapsulation or in situ crosslinking in the presence of cells and tissue. Here we describe the synthesis and characterization of maleimide-modified hyaluronic acid (HA) and gelatin, which are crosslinked using a bifunctional thiolated polyethylene glycol (PEG) crosslinker. Synthesized products were evaluated by proton nuclear magnetic resonance (NMR), ultraviolet visibility spectrometry, size exclusion chromatography, and pH sensitivity, which confirmed successful HA and gelatin modification, molecular weights, and readiness for crosslinking. Gelation testing both by visual and NMR confirmed successful and rapid crosslinking, after which the hydrogels were characterized by rheology, swelling assays, protein release, and barrier function against dextran diffusion. Lastly, biocompatibility was assessed in the presence of human dermal fibroblasts and keratinocytes, showing continued proliferation with or without the hydrogel. These initial studies present a defined, and well-characterized extracellular matrix (ECM)-based hydrogel platform with versatile properties suitable for a variety of applications in regenerative medicine and tissue engineering.
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http://dx.doi.org/10.3390/gels7010013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931058PMC
February 2021

Author Correction: Multicellular 3D Neurovascular Unit Model for Assessing Hypoxia and Neuroinflammation Induced Blood-Brain Barrier Dysfunction.

Sci Rep 2020 Nov 18;10(1):20384. Epub 2020 Nov 18.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27101, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-77348-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673116PMC
November 2020

Multicellular 3D Neurovascular Unit Model for Assessing Hypoxia and Neuroinflammation Induced Blood-Brain Barrier Dysfunction.

Sci Rep 2020 06 17;10(1):9766. Epub 2020 Jun 17.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27101, USA.

The blood-brain barrier (BBB) is a dynamic component of the brain-vascular interface that maintains brain homeostasis and regulates solute permeability into brain tissue. The expression of tight junction proteins between adjacent endothelial cells and the presence of efflux proteins prevents entry of foreign substances into the brain parenchyma. BBB dysfunction, however, is evident in many neurological disorders including ischemic stroke, trauma, and chronic neurodegenerative diseases. Currently, major contributors to BBB dysfunction are not well understood. Here, we employed a multicellular 3D neurovascular unit organoid containing human brain microvascular endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes and neurons to model the effects of hypoxia and neuroinflammation on BBB function. Organoids were cultured in hypoxic chamber with 0.1% O for 24 hours. Organoids cultured under this hypoxic condition showed increased permeability, pro-inflammatory cytokine production, and increased oxidative stress. The anti-inflammatory agents, secoisolariciresinol diglucoside and 2-arachidonoyl glycerol, demonstrated protection by reducing inflammatory cytokine levels in the organoids under hypoxic conditions. Through the assessment of a free radical scavenger and an anti-inflammatory endocannabinoid, we hereby report the utility of the model in drug development for drug candidates that may reduce the effects of ROS and inflammation under disease conditions. This 3D organoid model recapitulates characteristics of BBB dysfunction under hypoxic physiological conditions and when exposed to exogenous neuroinflammatory mediators and hence may have potential in disease modeling and therapeutic development.
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http://dx.doi.org/10.1038/s41598-020-66487-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7299970PMC
June 2020

Extrusion-Based Bioprinting: Current Standards and Relevancy for Human-Sized Tissue Fabrication.

Methods Mol Biol 2020 ;2140:65-92

Wake Forest Institute for Regenerative Medicine, Wake Forest University, Winston-Salem, NC, USA.

The field of bioengineering has long pursued the goal of fabricating large-scale tissue constructs for use both in vitro and in vivo. Recent technological advances have indicated that bioprinting will be a key technique in manufacturing these specimens. This chapter aims to provide an overview of what has been achieved to date through the use of microextrusion bioprinters and what major challenges still impede progress. Microextrusion printer configurations will be addressed along with critical design characteristics including nozzle specifications and bioink modifications. Significant challenges within the field with regard to achieving long-term cell viability and vascularization, and current research that shows promise in mitigating these challenges in the near future are discussed. While microextrusion is a broad field with many applications, this chapter aims to provide an overview of the field with a focus on its applications toward human-sized tissue constructs.
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http://dx.doi.org/10.1007/978-1-0716-0520-2_5DOI Listing
March 2021

Bioprinted Skin Recapitulates Normal Collagen Remodeling in Full-Thickness Wounds.

Tissue Eng Part A 2020 05 28;26(9-10):512-526. Epub 2020 Jan 28.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.

Over 1 million burn injuries are treated annually in the United States, and current tissue engineered skin fails to meet the need for full-thickness replacement. Bioprinting technology has allowed fabrication of full-thickness skin and has demonstrated the ability to close full-thickness wounds. However, analysis of collagen remodeling in wounds treated with bioprinted skin has not been reported. The purpose of this study is to demonstrate the utility of bioprinted skin for epidermal barrier formation and normal collagen remodeling in full-thickness wounds. Human keratinocytes, melanocytes, fibroblasts, dermal microvascular endothelial cells, follicle dermal papilla cells, and adipocytes were suspended in fibrinogen bioink and bioprinted to form a tri-layer skin structure. Bioprinted skin was implanted onto 2.5 × 2.5 cm full-thickness excisional wounds on athymic mice, compared with wounds treated with hydrogel only or untreated wounds. Total wound closure, epithelialization, and contraction were quantified, and skin samples were harvested at 21 days for histology. Picrosirius red staining was used to quantify collagen fiber orientation, length, and width. Immunohistochemical (IHC) staining was performed to confirm epidermal barrier formation, dermal maturation, vascularity, and human cell integration. All bioprinted skin treated wounds closed by day 21, compared with open control wounds. Wound closure in bioprinted skin treated wounds was primarily due to epithelialization. In contrast, control hydrogel and untreated groups had sparse wound coverage and incomplete closure driven primarily by contraction. Picrosirius red staining confirmed a normal basket weave collagen organization in bioprinted skin-treated wounds compared with parallel collagen fibers in hydrogel only and untreated wounds. IHC staining at day 21 demonstrated the presence of human cells in the regenerated dermis, the formation of a stratified epidermis, dermal maturation, and blood vessel formation in bioprinted skin, none of which was present in control hydrogel treated wounds. Bioprinted skin accelerated full-thickness wound closure by promoting epidermal barrier formation, without increasing contraction. This healing process is associated with human cells from the bioprinted skin laying down a healthy, basket-weave collagen network. The remodeled skin is phenotypically similar to human skin and composed of a composite of graft and infiltrating host cells. Impact statement We have demonstrated the ability of bioprinted skin to enhance closure of full-thickness wounds through epithelialization and normal collagen remodeling. To our knowledge, this article is the first to quantify collagen remodeling by bioprinted skin in full-thickness wounds. Our methods and results can be used to guide further investigation of collagen remodeling by tissue engineered skin products to improve ongoing and future bioprinting skin studies. Ultimately, our skin bioprinting technology could translate into a new treatment for full-thickness wounds in human patients with the ability to recapitulate normal collagen remodeling in full-thickness wounds.
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http://dx.doi.org/10.1089/ten.TEA.2019.0319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249461PMC
May 2020

Opportunities and challenges of translational 3D bioprinting.

Nat Biomed Eng 2020 04 6;4(4):370-380. Epub 2019 Nov 6.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.

3D-printed orthopaedic devices and surgical tools, printed maxillofacial implants and other printed acellular devices have been used in patients. By contrast, bioprinted living cellular constructs face considerable translational challenges. In this Perspective, we first summarize the most recent developments in 3D bioprinting for clinical applications, with a focus on how 3D-printed cartilage, bone and skin can be designed for individual patients and fabricated using the patient's own cells. We then discuss key translational considerations, such as the need to ensure close integration of the living device with the patient's vascular network, the development of biocompatible bioinks and the challenges in deriving a physiologically relevant number of cells. Lastly, we outline untested regulatory pathways, as well as logistical challenges in material sourcing, manufacturing, standardization and transportation.
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http://dx.doi.org/10.1038/s41551-019-0471-7DOI Listing
April 2020

Immune and Cytokine Dysfunction in Cystic Fibrosis.

Am J Respir Cell Mol Biol 2019 11;61(5):656-658

Wake Forest School of MedicineWinston-Salem, North Carolinaand.

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http://dx.doi.org/10.1165/rcmb.2018-0361LEDOI Listing
November 2019

Bioprinted trachea constructs with patient-matched design, mechanical and biological properties.

Biofabrication 2019 12 31;12(1):015022. Epub 2019 Dec 31.

Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States of America.

Tracheal stenosis is a rare but life-threatening disease. Primary clinical procedures for treating this disease are limited if the region requiring repair is long or complex. This study is the first of its kind to fabricate bioprinted tracheal constructs with separate cartilage and smooth muscle regions using polycaprolactone (PCL) and human mesenchymal stem cell (hMSC)-laden hydrogels. Our final bioprinted trachea showed comparable elastic modulus and yield stress compared to native tracheal tissue. In addition, both cartilage and smooth muscle formation were observed in the desired regions of our bioprinted trachea through immunohistochemistry and western blot after two weeks of in vitro culture. This study demonstrates a novel approach to manufacture tissue engineered trachea with mechanical and biological properties similar to native trachea, which represents a step closer to overcoming the clinical challenges of treating tracheal stenosis.
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http://dx.doi.org/10.1088/1758-5090/ab5354DOI Listing
December 2019

Stromal cells from perinatal and adult sources modulate the inflammatory immune response in vitro by decreasing Th1 cell proliferation and cytokine secretion.

Stem Cells Transl Med 2020 01 22;9(1):61-73. Epub 2019 Oct 22.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.

Many immune-mediated conditions are associated with a dysregulated imbalance toward a Th1 response leading to disease onset, severity, and damage. Many of the therapies such as immunomodulators or anti-TNF-α antibodies often fall short in preventing disease progression and ameliorating disease conditions. Thus, new therapies that can target inflammatory environments would have a major impact in preventing the progression of inflammatory diseases. We investigated the role of human stromal cells derived from the amniotic fluid (AFSCs), the placenta (PLSCs), and bone marrow-derived mesenchymal stromal cells (BM-MSCs) in modulating the inflammatory response of in vitro-stimulated circulating blood-derived immune cells. Immune cells were isolated from the blood of healthy individuals and stimulated in vitro with antigens to activate inflammatory responses to stimuli. AFSC, BM-MSCs, and PLSCs were cocultured with stimulated leukocytes, neutrophils, or lymphocytes. Inflammatory cytokine production, neutrophil migration, enzymatic degranulation, T cell proliferation, and subsets were evaluated. Coculture of all three stromal cell types decreased the gene expression of inflammatory cytokines and enzymes such as IL-1β, IFN-γ, TNF-α, neutrophil elastase, and the transcription factor NF-κB in lipopolysaccharide-stimulated leukocytes. With isolated phytohemagglutinin-stimulated peripheral blood mononuclear cells, cells coculture leads to a decrease in lymphocyte proliferation. This effect correlated with decreased numbers of Th1 lymphocytes and decreased secreted levels of IFN-γ.
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http://dx.doi.org/10.1002/sctm.19-0123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6954711PMC
January 2020

Amnion membrane hydrogel and amnion membrane powder accelerate wound healing in a full thickness porcine skin wound model.

Stem Cells Transl Med 2020 01 21;9(1):80-92. Epub 2019 Jul 21.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina.

There is a need for effective wound treatments that retain the bioactivity of a cellular treatment, but without the high costs and complexities associated with manufacturing, storing, and applying living biological products. Previously, we developed an amnion membrane-derived hydrogel and evaluated its wound healing properties using a mouse wound model. In this study, we used a full thickness porcine skin wound model to evaluate the wound-healing efficacy of the amnion hydrogel and a less-processed amnion product comprising a lyophilized amnion membrane powder. These products were compared with commercially available amnion and nonamnion wound healing products. We found that the amnion hydrogel and amnion powder treatments demonstrated significant and rapid wound healing, driven primarily by new epithelialization versus closure by contraction. Histological analysis demonstrated that these treatments promote the formation of a mature epidermis and dermis with similar composition to healthy skin. The positive skin regenerative outcomes using amnion hydrogel and amnion powder treatments in a large animal model further demonstrate their potential translational value for human wound treatments.
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http://dx.doi.org/10.1002/sctm.19-0101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6954699PMC
January 2020

Cystic Fibrosis Inflammation: Hyperinflammatory, Hypoinflammatory, or Both?

Am J Respir Cell Mol Biol 2019 Sep;61(3):273-274

Marsico Lung Institute/Cystic Fibrosis CenterUniversity of North Carolina at Chapel HillChapel Hill, North Carolina.

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http://dx.doi.org/10.1165/rcmb.2019-0107EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839932PMC
September 2019

In Situ Bioprinting of Autologous Skin Cells Accelerates Wound Healing of Extensive Excisional Full-Thickness Wounds.

Sci Rep 2019 02 12;9(1):1856. Epub 2019 Feb 12.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157, USA.

The early treatment and rapid closure of acute or chronic wounds is essential for normal healing and prevention of hypertrophic scarring. The use of split thickness autografts is often limited by the availability of a suitable area of healthy donor skin to harvest. Cellular and non-cellular biological skin-equivalents are commonly used as an alternative treatment option for these patients, however these treatments usually involve multiple surgical procedures and associated with high costs of production and repeated wound treatment. Here we describe a novel design and a proof-of-concept validation of a mobile skin bioprinting system that provides rapid on-site management of extensive wounds. Integrated imaging technology facilitated the precise delivery of either autologous or allogeneic dermal fibroblasts and epidermal keratinocytes directly into an injured area, replicating the layered skin structure. Excisional wounds bioprinted with layered autologous dermal fibroblasts and epidermal keratinocytes in a hydrogel carrier showed rapid wound closure, reduced contraction and accelerated re-epithelialization. These regenerated tissues had a dermal structure and composition similar to healthy skin, with extensive collagen deposition arranged in large, organized fibers, extensive mature vascular formation and proliferating keratinocytes.
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http://dx.doi.org/10.1038/s41598-018-38366-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372693PMC
February 2019

Current Challenges of Bioprinted Tissues Toward Clinical Translation.

Tissue Eng Part B Rev 2019 02 12;25(1):1-13. Epub 2018 Oct 12.

Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina.

Impact Statement: This review has a broad overview of the current challenges of bioprinted tissues towards clinical translations and future directions to overcome those challenges. The development of this field has a huge impact on the situation of an insufficient number of organ donors for life-saving organ transplantations.
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http://dx.doi.org/10.1089/ten.TEB.2018.0132DOI Listing
February 2019

Rethinking Regenerative Medicine From a Transplant Perspective (and Vice Versa).

Transplantation 2019 02;103(2):237-249

Department of Cellular and Molecular Physiology, Centre for Preclinical Imaging, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.

No field in health sciences has more interest than organ transplantation in fostering progress in regenerative medicine (RM) because the future of no other field more than the future of organ transplantation will be forged by progress occurring in RM. In fact, the most urgent needs of modern transplant medicine, namely, more organs to satisfy the skyrocketing demand and immunosuppression-free transplantation, cannot be met in full with current technologies and are at risk of remaining elusive goals. Instead, in the past few decades, groundbreaking progress in RM is suggesting a different approach to the problem. New, RM-inspired technologies among which decellularization, 3-dimensional printing and interspecies blastocyst complementation, promise organoids manufactured from the patients' own cells and bear potential to render the use of currently used allografts obsolete. Transplantation, a field that has traditionally been immunology-based, is therefore destined to become a RM-based discipline. However, the contours of RM remain unclear, mainly due to the lack of a universally accepted definition, the lack of clarity of its potential modalities of application and the unjustified and misleading hype that often follows the reports of clinical application of RM technologies. All this generates excessive and unmet expectations and an erroneous perception of what RM really is and can offer. In this article, we will (1) discuss these aspects of RM and transplant medicine, (2) propose a definition of RM, and (3) illustrate the state of the art of the most promising RM-based technologies of transplant interest.
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http://dx.doi.org/10.1097/TP.0000000000002370DOI Listing
February 2019

Solubilized Amnion Membrane Hyaluronic Acid Hydrogel Accelerates Full-Thickness Wound Healing.

Stem Cells Transl Med 2017 11 23;6(11):2020-2032. Epub 2017 Sep 23.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, USA.

The early and effective treatment of wounds is vital to ensure proper wound closure and healing with appropriate functional and cosmetic outcomes. The use of human amnion membranes for wound care has been shown to be safe and effective. However, the difficulty in handling and placing thin sheets of membrane, and the high costs associated with the use of living cellularized tissue has limited the clinical application of amniotic membrane wound healing products. Here, we describe a novel amnion membrane-derived product, processed to result in a cell-free solution, while maintaining high concentrations of cell-derived cytokines and growth factors. The solubilized amnion membrane (SAM) combined with the carrier hyaluronic acid (HA) hydrogel (HA-SAM) is easy to produce, store, and apply to wounds. We demonstrated the efficacy of HA-SAM as a wound treatment using a full-thickness murine wound model. HA-SAM significantly accelerated wound closure through re-epithelialization and prevented wound contraction. HA-SAM-treated wounds had thicker regenerated skin, increased total number of blood vessels, and greater numbers of proliferating keratinocytes within the epidermis. Overall, this study confirms the efficacy of the amnion membrane as a wound treatment/dressing, and overcomes many of the limitations associated with using fresh, cryopreserved, or dehydrated tissue by providing a hydrogel delivery system for SAM. Stem Cells Translational Medicine 2017;6:2020-2032.
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http://dx.doi.org/10.1002/sctm.17-0053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430059PMC
November 2017

Multi-tissue interactions in an integrated three-tissue organ-on-a-chip platform.

Sci Rep 2017 08 18;7(1):8837. Epub 2017 Aug 18.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157, USA.

Many drugs have progressed through preclinical and clinical trials and have been available - for years in some cases - before being recalled by the FDA for unanticipated toxicity in humans. One reason for such poor translation from drug candidate to successful use is a lack of model systems that accurately recapitulate normal tissue function of human organs and their response to drug compounds. Moreover, tissues in the body do not exist in isolation, but reside in a highly integrated and dynamically interactive environment, in which actions in one tissue can affect other downstream tissues. Few engineered model systems, including the growing variety of organoid and organ-on-a-chip platforms, have so far reflected the interactive nature of the human body. To address this challenge, we have developed an assortment of bioengineered tissue organoids and tissue constructs that are integrated in a closed circulatory perfusion system, facilitating inter-organ responses. We describe a three-tissue organ-on-a-chip system, comprised of liver, heart, and lung, and highlight examples of inter-organ responses to drug administration. We observe drug responses that depend on inter-tissue interaction, illustrating the value of multiple tissue integration for in vitro study of both the efficacy of and side effects associated with candidate drugs.
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http://dx.doi.org/10.1038/s41598-017-08879-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562747PMC
August 2017

Immunomodulatory Cell Therapy to Target Cystic Fibrosis Inflammation.

Am J Respir Cell Mol Biol 2018 Jan;58(1):12-20

1 Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.

Cystic fibrosis (CF) is associated with exaggerated and prolonged inflammation in the lungs, which contributes to lung injury, airway mucus obstruction, bronchiectasis, and loss of lung function. This hyperinflammatory phenotype appears to be caused by an imbalance between the pro- and antiinflammatory regulatory pathways, with heightened proinflammatory stimuli, a decreased counter-regulatory response, and reduced effectiveness of immune cell function and inflammatory resolution. Thus, therapies that can target this inflammatory environment would have a major impact on preventing the progression of lung disease. Because of the complex phenotype of CF inflammation, current antiinflammatory regimens have proven to be inadequate for the targeting of these multiple dysregulated pathways and effects. Several approaches using cell therapies have shown potential therapeutic benefit for the treatment of CF inflammation. This review provides an overview of the immune dysfunctions in CF and current therapeutic regimens; explores the field of cell therapy as a treatment for CF inflammation; and focuses on the various cell types used, their immunomodulatory functions, and the current approaches to mitigate the inflammatory response and reduce the long-term damage for patients with CF.
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http://dx.doi.org/10.1165/rcmb.2017-0160TRDOI Listing
January 2018

A tunable hydrogel system for long-term release of cell-secreted cytokines and bioprinted in situ wound cell delivery.

J Biomed Mater Res B Appl Biomater 2017 10 28;105(7):1986-2000. Epub 2016 Jun 28.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina.

For many cellular therapies being evaluated in preclinical and clinical trials, the mechanisms behind their therapeutic effects appear to be the secretion of growth factors and cytokines, also known as paracrine activity. Often, delivered cells are transient, and half-lives of the growth factors that they secrete are short, limiting their long-term effectiveness. The goal of this study was to optimize a hydrogel system capable of in situ cell delivery that could sequester and release growth factors secreted from those cells after the cells were no longer present. Here, we demonstrate the use of a fast photocross-linkable heparin-conjugated hyaluronic acid (HA-HP) hydrogel as a cell delivery vehicle for sustained growth factor release, which extends paracrine activity. The hydrogel could be modulated through cross-linking geometries and heparinization to support sustained release proteins and heparin-binding growth factors. To test the hydrogel in vivo, we used it to deliver amniotic fluid-derived stem (AFS) cells, which are known to secrete cytokines and growth factors, in full thickness skin wounds in a nu/nu murine model. Despite transience of the AFS cells in vivo, the HA-HP hydrogel with AFS cells improved wound closure and reepithelialization and increased vascularization and production of extracellular matrix in vivo. These results suggest that HA-HP hydrogel has the potential to prolong the paracrine activity of cells, thereby increasing their therapeutic effectiveness in wound healing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1986-2000, 2017.
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http://dx.doi.org/10.1002/jbm.b.33736DOI Listing
October 2017

IMAGE AND VIDEO ACQUISITION AND PROCESSING FOR CLINICAL APPLICATIONS.

Biomed Eng Comput Biol 2016 16;7(Suppl 1):35-8. Epub 2016 Jun 16.

Assistant Professor of Biomedical Engineering, College of Engineering, Wayne State University, Detroit, MI, USA.

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http://dx.doi.org/10.4137/BECB.S40272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4912230PMC
June 2016

Fluorescent Cell Imaging in Regenerative Medicine.

Biomed Eng Comput Biol 2016 2;7(Suppl 1):29-33. Epub 2016 May 2.

Wake Forest Institute for Regenerative Medicine, Winston-Salem, NC, USA.; Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, Wake Forest Baptist Health, Winston-Salem, NC, USA.

Fluorescent protein imaging, a promising tool in biological research, incorporates numerous applications that can be of specific use in the field of regenerative medicine. To enhance tissue regeneration efforts, scientists have been developing new ways to monitor tissue development and maturation in vitro and in vivo. To that end, new imaging tools and novel fluorescent proteins have been developed for the purpose of performing deep-tissue high-resolution imaging. These new methods, such as intra-vital microscopy and Förster resonance energy transfer, are providing new insights into cellular behavior, including cell migration, morphology, and phenotypic changes in a dynamic environment. Such applications, combined with multimodal imaging, significantly expand the utility of fluorescent protein imaging in research and clinical applications of regenerative medicine.
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http://dx.doi.org/10.4137/BECB.S39045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4854300PMC
May 2016

Lung-On-A-Chip Technologies for Disease Modeling and Drug Development.

Biomed Eng Comput Biol 2016 20;7(Suppl 1):17-27. Epub 2016 Apr 20.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.

Animal and two-dimensional cell culture models have had a profound impact on not only lung research but also medical research at large, despite inherent flaws and differences when compared with in vivo and clinical observations. Three-dimensional (3D) tissue models are a natural progression and extension of existing techniques that seek to plug the gaps and mitigate the drawbacks of two-dimensional and animal technologies. In this review, we describe the transition of historic models to contemporary 3D cell and organoid models, the varieties of current 3D cell and tissue culture modalities, the common methods for imaging these models, and finally, the applications of these models and imaging techniques to lung research.
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http://dx.doi.org/10.4137/BECB.S34252DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4839966PMC
April 2016

Stem Cell Therapy for Treatment of Stress Urinary Incontinence: The Current Status and Challenges.

Stem Cells Int 2016 10;2016:7060975. Epub 2016 Jan 10.

Department of Urology, Affiliated Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.

Stress urinary incontinence (SUI) is a common urinary system disease that mostly affects women. Current treatments still do not solve the critical problem of urethral sphincter dysfunction. In recent years, there have been major developments in techniques to obtain, culture, and characterize autologous stem cells as well as many studies describing their applications for the treatment of SUI. In this paper, we review recent publications and clinical trials investigating the applications of several stem cell types as potential treatments for SUI and the underlying challenges of such therapy.
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http://dx.doi.org/10.1155/2016/7060975DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737006PMC
February 2016

Kidney transplantation, bioengineering and regeneration: an originally immunology-based discipline destined to transition towards ad hoc organ manufacturing and repair.

Expert Rev Clin Immunol 2016 4;12(2):169-82. Epub 2015 Dec 4.

a Department of Surgery , Wake Forest University , Winston Salem , NC , USA.

Kidney transplantation (KT), as a modality of renal replacement therapy (RRT), has been shown to be both economically and functionally superior to dialysis for the treatment of end-stage renal disease (ESRD). Progress in KT is limited by two major barriers: a) a chronic and burgeoning shortage of transplantable organs and b) the need for chronic immunosuppression following transplantation. Although ground-breaking advances in transplant immunology have improved patient survival and graft durability, a new pathway of innovation is needed in order to overcome current obstacles. Regenerative medicine (RM) holds the potential to shift the paradigm in RRT, through organ bioengineering. Manufactured organs represent a potentially inexhaustible source of transplantable grafts that would bypass the need for immunosuppressive drugs by using autologous cells to repopulate extracellular matrix (ECM) scaffolds. This overview discusses the current status of renal transplantation while reviewing the most promising innovations in RM therapy as applied to RRT.
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http://dx.doi.org/10.1586/1744666X.2016.1112268DOI Listing
November 2016

Use of trimetasphere metallofullerene MRI contrast agent for the non-invasive longitudinal tracking of stem cells in the lung.

Methods 2016 Apr 10;99:99-111. Epub 2015 Nov 10.

Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA. Electronic address:

Magnetic Resonance Imaging (MRI) is a commonly used, non-invasive imaging technique that provides visualization of soft tissues with high spatial resolution. In both a research and clinical setting, the major challenge has been identifying a non-invasive and safe method for longitudinal tracking of delivered cells in vivo. The labeling and tracking of contrast agent labeled cells using MRI has the potential to fulfill this need. Contrast agents are often used to enhance the image contrast between the tissue of interest and surrounding tissues with MRI. The most commonly used MRI contrast agents contain Gd(III) ions. However, Gd(III) ions are highly toxic in their ionic form, as they tend to accumulate in the liver, spleen, kidney and bones and block calcium channels. Endohedral metallofullerenes such as trimetallic nitride endohedral metallofullerenes (Trimetasphere®) are one unique class of fullerene molecules where a Gd3N cluster is encapsulated inside a C80 carbon cage referred to as [email protected] These endohedral metallofullerenes have several advantages over small chelated Gd(III) complexes such as increased stability of the Gd(III) ion, minimal toxic effects, high solubility in water and high proton relativity. In this study, we describe the evaluation of gadolinium-based Trimetasphere® positive contrast agent for the ​in vitro labeling and in vivo tracking of human amniotic fluid-derived stem cells within lung tissue. In addition, we conducted a 'proof-of-concept' experiment demonstrating that this methodology can be used to track the homing of stem cells to injured lung tissue and provide longitudinal analysis of cell localization over an extended time course.
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http://dx.doi.org/10.1016/j.ymeth.2015.11.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4829459PMC
April 2016

Tissue performance of bladder following stretched electrospun silk fibroin matrix and bladder acellular matrix implantation in a rabbit model.

J Biomed Mater Res A 2016 Jan 14;104(1):9-16. Epub 2015 Jul 14.

Department of Urology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.

The goal of this study was to investigate the tissue performance of bladder following stretched electrospun silk fibroin matrix (SESFM) implantation compared with bladder acellular matrix (BAM). We compared SESFM with BAM based on porosity and pore size. Scaffolds were separately transplanted into opposite walls of the bladder of 30 rabbits after stripping the bladder mucosa and smooth muscle (1.5 × 2.0 cm(2)). Gross anatomical observation, histological analysis and muscle contractility studies were performed at 2, 4, and 8 weeks post-op. SESFM has higher porosity and larger pore size compared with BAM (p < 0.05). At 2 weeks, the presence of vesical calculus was evident in 7/10 rabbits. Histological analysis showed that SESFM and BAM promoted similar degree of urothelium regeneration (p > 0.05). However, SESFM promoted a higher degree of smooth muscle and vessel regeneration compared to BAM (p < 0.05). In addition, muscle strips supported by SESFM displayed higher contractile responses to carbachol, KCl, and phenylephrine compared with BAM. At 8 weeks, both matrices elicited similar mild acute and chronic inflammatory reactions. Our results demonstrated that SESFM has greater ability to promote bladder tissue regeneration with structural and functional properties compared to BAM, and with similar biocompatibility.
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http://dx.doi.org/10.1002/jbm.a.35535DOI Listing
January 2016

Prospect for kidney bioengineering: shortcomings of the status quo.

Expert Opin Biol Ther 2015 Apr 1;15(4):547-58. Epub 2015 Feb 1.

Wake Forest School of Medicine , Winston-Salem, NC , USA.

Introduction: Dialysis and renal transplantation are the only two therapeutic options offered to patients affected by end-stage kidney disease; however, neither treatment can be considered definitive. In fact, dialysis is able to replace only the filtration function of the kidney without substituting its endocrine and metabolic roles, and dramatically impacts on patient's quality of life. On the other hand, kidney transplantation is severely limited by the shortage of transplantable organs, the need for immunosuppressive therapies and a narrow half-life. Regenerative medicine approaches are promising tools aiming to improve this condition.

Areas Covered: Cell therapies, bioartificial kidney, organ bioengineering, 3D printer and kidney-on-chip represent the most appealing areas of research for the treatment of end-stage kidney failure. The scope of this review is to summarize the state of the art, limits and directions of each branch.

Expert Opinion: In the future, these emerging technologies could provide definitive, curative and theoretically infinite options for the treatment of end-stage kidney disease. Progress in stem cells-based therapies, decellularization techniques and the more recent scientific know-how for the use of the 3D printer and kidney-on-chip could lead to a perfect cellular-based therapy, the futuristic creation of a bioengineered kidney in the lab or to a valid bioartificial alternative.
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http://dx.doi.org/10.1517/14712598.2015.993376DOI Listing
April 2015

Isolation, cryopreservation and culture of human amnion epithelial cells for clinical applications.

J Vis Exp 2014 Dec 21(94). Epub 2014 Dec 21.

The Ritchie Centre, Monash Institute of Medical Research, Monash University.

Human amnion epithelial cells (hAECs) derived from term or pre-term amnion membranes have attracted attention from researchers and clinicians as a potential source of cells for regenerative medicine. The reason for this interest is evidence that these cells have highly multipotent differentiation ability, low immunogenicity, and anti-inflammatory functions. These properties have prompted researchers to investigate the potential of hAECs to be used to treat a variety of diseases and disorders in pre-clinical animal studies with much success. hAECs have found widespread application for the treatment of a range of diseases and disorders. Potential clinical applications of hAECs include the treatment of stroke, multiple sclerosis, liver disease, diabetes and chronic and acute lung diseases. Progressing from pre-clinical animal studies into clinical trials requires a higher standard of quality control and safety for cell therapy products. For safety and quality control considerations, it is preferred that cell isolation protocols use animal product-free reagents. We have developed protocols to allow researchers to isolate, cryopreserve and culture hAECs using animal product-free reagents. The advantage of this method is that these cells can be isolated, characterized, cryopreserved and cultured without the risk of delivering potentially harmful animal pathogens to humans, while maintaining suitable cell yields, viabilities and growth potential. For researchers moving from pre-clinical animal studies to clinical trials, these methodologies will greatly accelerate regulatory approval, decrease risks and improve the quality of their therapeutic cell population.
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http://dx.doi.org/10.3791/52085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356357PMC
December 2014

Measuring respiratory function in mice using unrestrained whole-body plethysmography.

J Vis Exp 2014 Aug 12(90):e51755. Epub 2014 Aug 12.

The Ritchie Centre, Monash Institute of Medical Research; Department of Obstetrics and Gynaecology, Monash Medical Centre.

Respiratory dysfunction is one of the leading causes of morbidity and mortality in the world and the rates of mortality continue to rise. Quantitative assessment of lung function in rodent models is an important tool in the development of future therapies. Commonly used techniques for assessing respiratory function including invasive plethysmography and forced oscillation. While these techniques provide valuable information, data collection can be fraught with artefacts and experimental variability due to the need for anesthesia and/or invasive instrumentation of the animal. In contrast, unrestrained whole-body plethysmography (UWBP) offers a precise, non-invasive, quantitative way by which to analyze respiratory parameters. This technique avoids the use of anesthesia and restraints, which is common to traditional plethysmography techniques. This video will demonstrate the UWBP procedure including the equipment set up, calibration and lung function recording. It will explain how to analyze the collected data, as well as identify experimental outliers and artefacts that results from animal movement. The respiratory parameters obtained using this technique include tidal volume, minute volume, inspiratory duty cycle, inspiratory flow rate and the ratio of inspiration time to expiration time. UWBP does not rely on specialized skills and is inexpensive to perform. A key feature of UWBP, and most appealing to potential users, is the ability to perform repeated measures of lung function on the same animal.
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http://dx.doi.org/10.3791/51755DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827935PMC
August 2014

3D bioprinting of tissues and organs.

Nat Biotechnol 2014 Aug;32(8):773-85

Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA.

Additive manufacturing, otherwise known as three-dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education and medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.
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http://dx.doi.org/10.1038/nbt.2958DOI Listing
August 2014