1
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Jalloh US, Gsell A, Gultian KA, MacAulay J, Madden A, Smith J, Siri L, Vega SL. Synthesis and Photopatterning of Synthetic Thiol-Norbornene Hydrogels. Gels 2024; 10:164. [PMID: 38534582 DOI: 10.3390/gels10030164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/16/2024] [Accepted: 02/21/2024] [Indexed: 03/28/2024] Open
Abstract
Hydrogels are a class of soft biomaterials and the material of choice for a myriad of biomedical applications due to their biocompatibility and highly tunable mechanical and biochemical properties. Specifically, light-mediated thiol-norbornene click reactions between norbornene-modified macromers and di-thiolated crosslinkers can be used to form base hydrogels amenable to spatial biochemical modifications via subsequent light reactions between pendant norbornenes in the hydrogel network and thiolated peptides. Macromers derived from natural sources (e.g., hyaluronic acid, gelatin, alginate) can cause off-target cell signaling, and this has motivated the use of synthetic macromers such as poly(ethylene glycol) (PEG). In this study, commercially available 8-arm norbornene-modified PEG (PEG-Nor) macromers were reacted with di-thiolated crosslinkers (dithiothreitol, DTT) to form synthetic hydrogels. By varying the PEG-Nor weight percent or DTT concentration, hydrogels with a stiffness range of 3.3 kPa-31.3 kPa were formed. Pendant norbornene groups in these hydrogels were used for secondary reactions to either increase hydrogel stiffness (by reacting with DTT) or to tether mono-thiolated peptides to the hydrogel network. Peptide functionalization has no effect on bulk hydrogel mechanics, and this confirms that mechanical and biochemical signals can be independently controlled. Using photomasks, thiolated peptides can also be photopatterned onto base hydrogels, and mesenchymal stem cells (MSCs) attach and spread on RGD-functionalized PEG-Nor hydrogels. MSCs encapsulated in PEG-Nor hydrogels are also highly viable, demonstrating the ability of this platform to form biocompatible hydrogels for 2D and 3D cell culture with user-defined mechanical and biochemical properties.
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Affiliation(s)
- Umu S Jalloh
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Arielle Gsell
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Kirstene A Gultian
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - James MacAulay
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Abigail Madden
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Jillian Smith
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Luke Siri
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Sebastián L Vega
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
- Department of Orthopaedic Surgery, Cooper Medical School of Rowan University, Camden, NJ 08103, USA
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2
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Zhang W, Wang B, Xiang G, Jiang T, Zhao X. Photodynamic Alginate Zn-MOF Thermosensitive Hydrogel for Accelerated Healing of Infected Wounds. ACS APPLIED MATERIALS & INTERFACES 2023; 15:22830-22842. [PMID: 37129874 DOI: 10.1021/acsami.2c23321] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Antibiotic resistance reduces the effectiveness of infected wound healing, and it is necessary to develop a new strategy to promote infected wound healing without using antibiotics. Here, we develop a Chlorin e6 (Ce6)-loaded zinc-metal-organic framework (MOF) thermosensitive hydrogel (Ce6@MOF-Gel) based on alginate and poly(propylene glycol) 407, which enhances antibacterial effects and promotes infected wound healing by a novel strategy of combining zinc-MOF with photodynamic therapy (PDT). Zinc-MOF can realize acid-responsive release of Ce6 and improve antibacterial performance without drug resistance by destroying the integrity of bacterial cell membranes and enhancing the production of bacterial reactive oxygen species (ROS). Additionally, Ce6@MOF-Gel enhances the stability, solubility, and photodynamic properties of Ce6. More importantly, Ce6@MOF-Gel reduces inflammation and promotes collagen deposition and re-epithelialization to facilitate infected wound healing. Collectively, the photodynamic MOF-based hydrogel provides a new, efficient, and safe way for accelerated healing of infected wounds.
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Affiliation(s)
- Wenshang Zhang
- Key Laboratory of Marine Drugs, Ministry of Education, Shandong Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Bingjie Wang
- Key Laboratory of Marine Drugs, Ministry of Education, Shandong Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Guangli Xiang
- Key Laboratory of Marine Drugs, Ministry of Education, Shandong Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Tianze Jiang
- Key Laboratory of Marine Drugs, Ministry of Education, Shandong Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xia Zhao
- Key Laboratory of Marine Drugs, Ministry of Education, Shandong Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
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3
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Stöberl S, Balles M, Kellerer T, Rädler JO. Photolithographic microfabrication of hydrogel clefts for cell invasion studies. LAB ON A CHIP 2023; 23:1886-1895. [PMID: 36867426 DOI: 10.1039/d2lc01105k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Invasion of migrating cells into surrounding tissue plays a key role in cancer metastasis and immune response. In order to assess invasiveness, most in vitro invasion assays measure the degree to which cells migrate between microchambers that provide a chemoattractant gradient across a polymeric membrane with defined pores. However, in real tissue cells experience soft, mechanically deformable microenvironments. Here we introduce RGD-functionalized hydrogel structures that present pressurized clefts for invasive migration of cells between reservoirs maintaining a chemotactic gradient. Using UV-photolithography, equally spaced blocks of polyethylene glycol-norbornene (PEG-NB) hydrogels are formed, which subsequently swell and close the interjacent gaps. The swelling ratio and final contours of the hydrogel blocks were determined using confocal microscopy confirming a swelling induced closure of the structures. The velocity profile of cancer cells transmigrating through the clefts, which we name 'sponge clamp', is found to depend on the elastic modulus as well as the gap size between the swollen blocks. The 'sponge clamp' discriminates the invasiveness of two distinct cell lines, MDA-MB-231 and HT-1080. The approach provides soft 3D-microstructures mimicking invasion conditions in extracellular matrix.
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Affiliation(s)
- Stefan Stöberl
- Faculty of Physics and Center for NanoScience, Ludwig Maximilians-University, Munich, Germany.
| | - Miriam Balles
- Faculty of Physics and Center for NanoScience, Ludwig Maximilians-University, Munich, Germany.
| | - Thomas Kellerer
- Faculty of Physics and Center for NanoScience, Ludwig Maximilians-University, Munich, Germany.
- Department of Applied Science and Mechatronics, University of Applied Science, Munich, Germany
| | - Joachim O Rädler
- Faculty of Physics and Center for NanoScience, Ludwig Maximilians-University, Munich, Germany.
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4
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Vieira S, Silva-Correia J, Reis RL, Oliveira JM. Engineering Hydrogels for Modulation of Material-Cell Interactions. Macromol Biosci 2022; 22:e2200091. [PMID: 35853666 DOI: 10.1002/mabi.202200091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/29/2022] [Indexed: 11/06/2022]
Abstract
Hydrogels are a recurrent platform for Tissue Engineering (TE) strategies. Their versatility and the variety of available methods for tuning their properties highly contribute to hydrogels' success. As a result, the design of advanced hydrogels has been thoroughly studied, in the quest for better solutions not only for drugs- and cell-based therapies but also for more fundamental studies. The wide variety of sources, crosslinking strategies, and functionalization methods, and mostly the resemblance of hydrogels to the natural extracellular matrix, make this 3D hydrated structures an excellent tool for TE approaches. The state-of-the-art information regarding hydrogel design, processing methods, and the influence of different hydrogel formulations on the final cell-biomaterial interactions are overviewed herein. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Sílvia Vieira
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Joana Silva-Correia
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rui L Reis
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - J Miguel Oliveira
- 3B's Research Group, I3Bs - Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
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5
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Wiley KL, Sutherland BP, Ogunnaike BA, Kloxin AM. Rational Design of Hydrogel Networks with Dynamic Mechanical Properties to Mimic Matrix Remodeling. Adv Healthc Mater 2022; 11:e2101947. [PMID: 34936227 DOI: 10.1002/adhm.202101947] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/09/2021] [Indexed: 12/15/2022]
Abstract
Engineered hydrogels are increasingly used as extracellular matrix (ECM) surrogates for probing cell function in response to ECM remodeling events related to injury or disease (e.g., degradation followed by deposition/crosslinking). Inspired by these events, this work establishes an approach for pseudo-reversible mechanical property modulation in synthetic hydrogels by integrating orthogonal, enzymatically triggered crosslink degradation, and light-triggered photopolymerization stiffening. Hydrogels are formed by a photo-initiated thiol-ene reaction between multiarm polyethylene glycol and a dually enzymatically degradable peptide linker, which incorporates a thrombin-degradable sequence for triggered softening and a matrix metalloproteinase (MMP)-degradable sequence for cell-driven remodeling. Hydrogels are stiffened by photopolymerization using a flexible, MMP-degradable polymer-peptide conjugate and multiarm macromers, increasing the synthetic matrix crosslink density while retaining degradability. Integration of these tools enables sequential softening and stiffening inspired by matrix remodeling events within loose connective tissues (Young's modulus (E) ≈5 to 1.5 to 6 kPa with >3x ΔE). The cytocompatibility and utility of this approach is examined with breast cancer cells, where cell proliferation shows a dependence on the timing of triggered softening. This work provides innovative tools for 3D dynamic property modulation that are synthetically accessible and cell compatible.
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Affiliation(s)
- Katherine L. Wiley
- Department of Chemical and Biomolecular Engineering University of Delaware Newark DE 19716 USA
| | - Bryan P. Sutherland
- Department of Chemical and Biomolecular Engineering University of Delaware Newark DE 19716 USA
| | - Babatunde A. Ogunnaike
- Department of Chemical and Biomolecular Engineering University of Delaware Newark DE 19716 USA
| | - April M. Kloxin
- Department of Chemical and Biomolecular Engineering University of Delaware Newark DE 19716 USA
- Department of Materials Science and Engineering University of Delaware Newark DE 19716 USA
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6
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Sabel-Grau T, Tyushina A, Babalik C, Lensen MC. UV-VIS Curable PEG Hydrogels for Biomedical Applications with Multifunctionality. Gels 2022; 8:gels8030164. [PMID: 35323277 PMCID: PMC8956119 DOI: 10.3390/gels8030164] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/26/2022] [Accepted: 03/03/2022] [Indexed: 12/26/2022] Open
Abstract
Multifunctional biomedical materials capable of integrating optical functions are highly desirable for many applications, such as advanced intra-ocular lens (IOL) implants. Therefore, poly(ethylene glycol)-diacrylate (PEG-DA) hydrogels are used with different photoinitiators (PI). In addition to standard UV PI Irgacure, Erythrosin B and Eosin Y are used as PI with high sensitivity in the optical range of the spectrum. The minimum PI concentrations for producing new hydrogels with PEG-DA and different PIs were determined. Hydrogel films were obtained, which were applicable for light-based patterning and, hence, the functionalization of surface and volume. Cytotoxicity tests confirm cytocompatibility of hydrogels and compositions. Exploiting the correlation of structure and function allows biomedical materials with multifunctionality.
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7
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Krieghoff J, Gronbach M, Schulz-Siegmund M, Hacker MC. Biodegradable macromers for implant bulk and surface engineering. Biol Chem 2021; 402:1357-1374. [PMID: 34433237 DOI: 10.1515/hsz-2021-0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 08/09/2021] [Indexed: 11/15/2022]
Abstract
Macromers, polymeric molecules with at least two functional groups for cross-polymerization, are interesting materials to tailor mechanical, biochemical and degradative bulk and surface properties of implants for tissue regeneration. In this review we focus on macromers with at least one biodegradable building block. Manifold design options, such as choice of polymeric block(s), optional core molecule and reactive groups, as well as cross-co-polymerization with suitable anchor or linker molecules, allow the adaptation of macromer-based biomaterials towards specific application requirements in both hard and soft tissue regeneration. Implants can be manufactured from macromers using additive manufacturing as well as molding and templating approaches. This review summarizes and discusses the overall concept of biodegradable macromers and recent approaches for macromer processing into implants as well as techniques for surface modification directed towards bone regeneration. These aspects are reviewed including a focus on the authors' contributions to the field through research within the collaborative research project Transregio 67.
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Affiliation(s)
- Jan Krieghoff
- Medical Faculty, Pharmaceutical Technology, Leipzig University, Eilenburger Str. 15A, D-04317 Leipzig, Germany.,Collaborative Research Center (SFB-TRR67) "Functional Biomaterials for Controlling Healing Processes in Bone and Skin - From Material Science to Clinical Application", Leipzig and Dresden, Germany
| | - Mathis Gronbach
- Medical Faculty, Pharmaceutical Technology, Leipzig University, Eilenburger Str. 15A, D-04317 Leipzig, Germany.,Collaborative Research Center (SFB-TRR67) "Functional Biomaterials for Controlling Healing Processes in Bone and Skin - From Material Science to Clinical Application", Leipzig and Dresden, Germany
| | - Michaela Schulz-Siegmund
- Medical Faculty, Pharmaceutical Technology, Leipzig University, Eilenburger Str. 15A, D-04317 Leipzig, Germany.,Collaborative Research Center (SFB-TRR67) "Functional Biomaterials for Controlling Healing Processes in Bone and Skin - From Material Science to Clinical Application", Leipzig and Dresden, Germany
| | - Michael C Hacker
- Medical Faculty, Pharmaceutical Technology, Leipzig University, Eilenburger Str. 15A, D-04317 Leipzig, Germany.,Collaborative Research Center (SFB-TRR67) "Functional Biomaterials for Controlling Healing Processes in Bone and Skin - From Material Science to Clinical Application", Leipzig and Dresden, Germany.,Institute of Pharmaceutics and Biopharmaceutics, Heinrich Heine University, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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8
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Wang JH, Tsai CW, Tsai NY, Chiang CY, Lin RS, Pereira RF, Li YCE. An injectable, dual crosslinkable hybrid pectin methacrylate (PECMA)/gelatin methacryloyl (GelMA) hydrogel for skin hemostasis applications. Int J Biol Macromol 2021; 185:441-450. [PMID: 34197849 DOI: 10.1016/j.ijbiomac.2021.06.162] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/18/2021] [Accepted: 06/24/2021] [Indexed: 12/14/2022]
Abstract
Biomaterials for effective hemorrhage control are urgently needed in clinics as uncontrolled bleeding is associated with high mortality. Herein, we developed an injectable and in situ photo-crosslinkable hybrid hemostatic hydrogel by combining pectin methacrylate (PECMA) and gelatin methacryloyl (GelMA). This modular material system combines ionic- and photo-crosslinking chemistries to design interpenetrating networks (IPN) exhibiting tunable rheology, highly porous structure, and controllable swelling and mechanical properties. By simply changing the calcium (0-15 mM) and polymer (1.5-7%) content used for the sequential crosslinking of hydrogels via calcium gelation and UV-photopolymerization, it was possible to precisely modulate the injectability, degradation, and swelling ratio. Moreover, it is demonstrated that PECMA/GelMA hydrogels present good cytocompatibility and uniquely synergize the hemostatic properties of calcium ions on PECMA, the amine residues on GelMA, and the highly porous network toward rapid blood absorption and fast coagulation effect. An in vitro porcine skin bleeding model confirmed that the hydrogel could be directly injected into the wound and rapidly photo-crosslinked, circumventing the bleeding and decreasing the coagulation time by 39%. Importantly, the crosslinked hydrogel could be easily removed to prevent secondary wound injury. Overall, this injectable hybrid PECMA/GelMA hydrogel stands as a promising hemostatic material.
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Affiliation(s)
- Jing-Han Wang
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan
| | - Ching-Wen Tsai
- Taiwan Instrument Research Institute, National Applied Research Laboratories, Hsinchu, Taiwan
| | - Nian-Yun Tsai
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan
| | - Chao-Ying Chiang
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan
| | - Ru-Sin Lin
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan
| | - Rúben F Pereira
- ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal; i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
| | - Yi-Chen Ethan Li
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan.
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9
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Uzcategui AC, Higgins CI, Hergert JE, Tomaschke AE, Crespo-Cuevas V, Ferguson VL, Bryant SJ, McLeod RR, Killgore JP. Microscale Photopatterning of Through-thickness Modulus in a Monolithic and Functionally Graded 3D Printed Part. SMALL SCIENCE 2021; 1:2000017. [PMID: 34458889 PMCID: PMC8388578 DOI: 10.1002/smsc.202000017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
3D printing is transforming traditional processing methods for applications ranging from tissue engineering to optics. To fulfill its maximum potential, 3D printing requires a robust technique for producing structures with precise three-dimensional (x, y and z) control of mechanical properties. Previous efforts to realize such spatial control of modulus within 3D printed parts have largely focused on low-resolution (mm to cm scale) multi-material processes and grayscale approaches that spatially vary the modulus in the x-y plane and energy dose-based (E = I 0 t exp) models that do not account for the resin's sub-linear response to irradiation intensity. Here, we demonstrate a novel approach for through-thickness (z) voxelated control of mechanical properties within a single-material, monolithic part. Control over the local modulus is enabled by a predictive model that incorporates the observed non-reciprocal dose response of the material. The model is validated by an application of atomic force microscopy to map the through-thickness modulus on multi-layered 3D parts. Overall, both smooth gradations (30 MPa change over ≈75 μm) and sharp step-changes (30 MPa change over ≈5 μm) in modulus are realized in poly(ethylene glycol) diacrylate based 3D constructs, paving the way for advancements in tissue engineering, stimuli-responsive 4D printing and graded metamaterials.
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Affiliation(s)
- Asais Camila Uzcategui
- Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Callie I. Higgins
- Applied Chemicals and Materials Division (647), National Institute of Standards and Technology (NIST), Boulder, CO 80305
| | - John E. Hergert
- Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Andrew E. Tomaschke
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA
| | - Victor Crespo-Cuevas
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA
| | - Virginia L. Ferguson
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Stephanie J. Bryant
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Robert R. McLeod
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Jason P. Killgore
- Applied Chemicals and Materials Division (647), National Institute of Standards and Technology (NIST), Boulder, CO 80305
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10
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Ngadimin KD, Stokes A, Gentile P, Ferreira AM. Biomimetic hydrogels designed for cartilage tissue engineering. Biomater Sci 2021; 9:4246-4259. [DOI: 10.1039/d0bm01852j] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cartilage-like hydrogels based on materials like gelatin, chondroitin sulfate, hyaluronic acid and polyethylene glycol are reviewed and contrasted, revealing existing limitations and challenges on biomimetic hydrogels for cartilage regeneration.
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Affiliation(s)
- Kresanti D. Ngadimin
- Faculty of Medical Sciences
- Newcastle University
- Newcastle upon Tyne
- UK
- Faculty of Medicine
| | - Alexander Stokes
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
| | - Piergiorgio Gentile
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
| | - Ana M. Ferreira
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
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11
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Zhu H, Yang H, Ma Y, Lu TJ, Xu F, Genin GM, Lin M. Spatiotemporally Controlled Photoresponsive Hydrogels: Design and Predictive Modeling from Processing through Application. ADVANCED FUNCTIONAL MATERIALS 2020; 30:2000639. [PMID: 32802013 PMCID: PMC7418561 DOI: 10.1002/adfm.202000639] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/16/2020] [Indexed: 05/16/2023]
Abstract
Photoresponsive hydrogels (PRHs) are soft materials whose mechanical and chemical properties can be tuned spatially and temporally with relative ease. Both photo-crosslinkable and photodegradable hydrogels find utility in a range of biomedical applications that require tissue-like properties or programmable responses. Progress in engineering with PRHs is facilitated by the development of theoretical tools that enable optimization of their photochemistry, polymer matrices, nanofillers, and architecture. This review brings together models and design principles that enable key applications of PRHs in tissue engineering, drug delivery, and soft robotics, and highlights ongoing challenges in both modeling and application.
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Affiliation(s)
- Hongyuan Zhu
- The Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'an710049P. R. China
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
| | - Haiqian Yang
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
| | - Yufei Ma
- The Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'an710049P. R. China
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
| | - Tian Jian Lu
- State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing210016P. R. China
- MOE Key Laboratory for Multifunctional Materials and StructuresXi'an Jiaotong UniversityXi'an710049P. R. China
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'an710049P. R. China
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
| | - Guy M. Genin
- The Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'an710049P. R. China
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
- Department of Mechanical Engineering & Materials ScienceWashington University in St. LouisSt. LouisMO63130USA
- NSF Science and Technology Center for Engineering MechanobiologyWashington University in St. LouisSt. LouisMO63130USA
| | - Min Lin
- The Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'an710049P. R. China
- Bioinspired Engineering & Biomechanics Center (BEBC)Xi'an Jiaotong UniversityXi'an710049P. R. China
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12
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Higgins CI, Killgore JP, DelRio FW, Bryant SJ, McLeod RR. Photo-tunable hydrogel mechanical heterogeneity informed by predictive transport kinetics model. SOFT MATTER 2020; 16:4131-4141. [PMID: 32202291 PMCID: PMC7489306 DOI: 10.1039/d0sm00052c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Understanding the three-dimensional (3D) mechanical and chemical properties of distinctly different, adjacent biological tissues is crucial to mimicking their complex properties with materials. 3D printing is a technique often employed to spatially control the distribution of the biomaterials, such as hydrogels, of interest, but it is difficult to print both mechanically robust (high modulus and toughness) and biocompatible (low modulus) hydrogels in a single structure. Moreover, due to the fast diffusion of mobile species during printing and nonequilibrium swelling conditions of low-solids-content hydrogels, it is challenging to form the high-fidelity structures required to mimic tissues. Here a predictive transport and swelling model is presented to model these effects and then is used to compensate for these effects during printing. This model is validated experimentally by photopatterning spatially distinct hydrogel elastic moduli using a single photo-tunable poly(ethylene glycol) (PEG) pre-polymer solution by sequentially patterning and in-diffusing fresh pre-polymer for further polymerization.
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Affiliation(s)
- Callie I Higgins
- Applied Chemicals and Materials Division, Material Measurement Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA.
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13
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Wiley KL, Ovadia EM, Calo CJ, Huber RE, Kloxin AM. Rate-based approach for controlling the mechanical properties of 'thiol-ene' hydrogels formed with visible light. Polym Chem 2019; 10:4428-4440. [PMID: 32405326 PMCID: PMC7218207 DOI: 10.1039/c9py00447e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mechanical properties of synthetic hydrogels traditionally have been controlled with the concentration, molecular weight, or stoichiometry of the macromolecular building blocks used for hydrogel formation. Recently, the rate of formation has been recognized as an important and effective handle for controlling the mechanical properties of these water-swollen polymer networks, owing to differences in network heterogeneity (e.g., defects) that arise based on the rate of gelation. Building upon this, in this work, we investigate a rate-based approach for controlling mechanical properties of hydrogels both initially and temporally with light. Specifically, synthetic hydrogels are formed with visible light-initiated thiol-ene 'click' chemistry (PEG-8-norbornene, dithiol linker, LAP photoinitiator with LED lamp centered at 455 nm), using irradiation conditions to control the rate of formation and the mechanical properties of the resulting hydrogels. Further, defects within these hydrogels were subsequently exploited for temporal modulation of mechanical properties with a secondary cure using low doses of long wavelength UV light (365 nm). The elasticity of the hydrogel, as measured with Young's and shear moduli, was observed to increase with increasing light intensity and concentration of photoinitiator used for hydrogel formation. In situ measurements of end group conversion during hydrogel formation with magic angle spinning (MAS 1H NMR) correlated with these mechanical properties measurements, suggesting that both dangling end groups and looping contribute to the observed mechanical properties. Dangling end groups provide reactive handles for temporal stiffening of hydrogels with a secondary UV-initiated thiol-ene polymerization, where an increase in Young's modulus by a factor of ~ 2.5x was observed. These studies demonstrate how the rate of photopolymerization can be tuned with irradiation wavelength, intensity, and time to control the properties of synthetic hydrogels, which may prove useful in a variety of applications from coatings to biomaterials for controlled cell culture and regenerative medicine.
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Affiliation(s)
- Katherine L Wiley
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States
| | - Elisa M Ovadia
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States
| | - Christopher J Calo
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States
| | - Rebecca E Huber
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States
| | - April M Kloxin
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States
- Department of Material Science and Engineering, University of Delaware, Newark, DE 19716, United States
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14
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Rao VV, Vu MK, Ma H, Killaars AR, Anseth KS. Rescuing mesenchymal stem cell regenerative properties on hydrogel substrates post serial expansion. Bioeng Transl Med 2019; 4:51-60. [PMID: 30680318 PMCID: PMC6336661 DOI: 10.1002/btm2.10104] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/15/2018] [Accepted: 06/21/2018] [Indexed: 02/06/2023] Open
Abstract
The use of human mesenchymal stem/stromal cells (hMSCs) in most clinical trials requires millions of cells/kg, necessitating ex vivo expansion typically on stiff substrates (tissue culture polystyrene [TCPS]), which induces osteogenesis and replicative senescence. Here, we quantified how serial expansion on TCPS influences proliferation, expression of hMSC-specific surface markers, mechanosensing, and secretome. Results show decreased proliferation and surface marker expression after five passages (P5) and decreased mechanosensing ability and cytokine production at later passages (P11-P12). Next, we investigated the capacity of poly(ethylene glycol) hydrogel matrices (E ~ 1 kPa) to rescue hMSC regenerative properties. Hydrogels reversed the reduction in cell surface marker expression observed at P5 on TCPS and increased secretion of cytokines for P11 hMSCs. Collectively, these results show that TCPS expansion significantly changes functional properties of hMSCs. However, some changes can be rescued by using hydrogels, suggesting that tailoring material properties could improve in vitro expansion methods.
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Affiliation(s)
- Varsha V. Rao
- Dept. of Chemical and Biological EngineeringUniversity of ColoradoBoulderCO, 80303
- BioFrontiers InstituteUniversity of ColoradoBoulderCO, 80303
| | - Michael K. Vu
- Dept. of Chemical and Biological EngineeringUniversity of ColoradoBoulderCO, 80303
- BioFrontiers InstituteUniversity of ColoradoBoulderCO, 80303
| | - Hao Ma
- Dept. of Chemical and Biological EngineeringUniversity of ColoradoBoulderCO, 80303
- BioFrontiers InstituteUniversity of ColoradoBoulderCO, 80303
| | - Anouk R. Killaars
- BioFrontiers InstituteUniversity of ColoradoBoulderCO, 80303
- Dept. of Materials Science and EngineeringUniversity of ColoradoBoulderCO, 80309
| | - Kristi S. Anseth
- Dept. of Chemical and Biological EngineeringUniversity of ColoradoBoulderCO, 80303
- BioFrontiers InstituteUniversity of ColoradoBoulderCO, 80303
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15
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van der Vlies AJ, Barua N, Nieves-Otero PA, Platt TG, Hansen RR. On Demand Release and Retrieval of Bacteria from Microwell Arrays Using Photodegradable Hydrogel Membranes. ACS APPLIED BIO MATERIALS 2018; 2:266-276. [DOI: 10.1021/acsabm.8b00592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- André J. van der Vlies
- Chemical Engineering Department, Kansas State University, 1701A Platt Street, Manhattan, Kansas 66506, United States
| | - Niloy Barua
- Chemical Engineering Department, Kansas State University, 1701A Platt Street, Manhattan, Kansas 66506, United States
| | - Priscila A. Nieves-Otero
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas 66506, United States
| | - Thomas G. Platt
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas 66506, United States
| | - Ryan R. Hansen
- Chemical Engineering Department, Kansas State University, 1701A Platt Street, Manhattan, Kansas 66506, United States
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16
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Liu HY, Nguyen HD, Lin CC. Dynamic PEG-Peptide Hydrogels via Visible Light and FMN-Induced Tyrosine Dimerization. Adv Healthc Mater 2018; 7:e1800954. [PMID: 30369100 DOI: 10.1002/adhm.201800954] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/01/2018] [Indexed: 02/03/2023]
Abstract
Photoresponsive hydrogels have become invaluable 3D culture matrices for mimicking aspects of the extracellular matrix. Recent efforts have focused on using ultraviolet (UV) light exposure and multifunctional macromers to induce secondary hydrogel crosslinking and dynamic matrix stiffening in the presence of cells. This contribution reports the design of a novel yet simple dynamic poly(ethylene glycol)-peptide hydrogel system through flavin mononucleotide (FMN) induced di-tyrosine crosslinking. These di-tyrosine linkages effectively increase hydrogel crosslinking density and elastic modulus. In addition, the degree of stiffening in hydrogels at a fixed PEG macromer content can be readily tuned by controlling FMN concentration or the number of tyrosine residues built-in to the peptide linker. Furthermore, tyrosine-bearing pendant biochemical motifs can be spatial-temporally patterned in the hydrogel network via controlling light exposure through a photomask. The visible light and FMN-induced tyrosine dimerization process produces a cytocompatible and physiologically relevant degree of stiffening, as shown by changes of cell morphology and gene expression in pancreatic cancer and stromal cells. This new dynamic hydrogel scheme should be highly desirable for researchers seeking a photoresponsive hydrogel system without complicated chemical synthesis and secondary UV light irradiation.
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Affiliation(s)
- Hung-Yi Liu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Han D Nguyen
- Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Chien-Chi Lin
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA
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17
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Glugla DJ, Chosy MB, Alim MD, Childress KK, Sullivan AC, McLeod RR. Multiple patterning of holographic photopolymers for increased refractive index contrast. OPTICS LETTERS 2018; 43:1866-1869. [PMID: 29652385 DOI: 10.1364/ol.43.001866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/17/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that multiple exposures of a two-component holographic photopolymer can quadruple the refractive index contrast of the material beyond the single-exposure saturation limit. Quantitative phase microscopy of isolated structures written by laser direct-write lithography is used to characterize the process. This technique reveals that multiple exposures are made possible by diffusion of the chemical components consumed during writing into the previously exposed regions. The ultimate index contrast is shown to be limited by the solubility of fresh components into the multiply exposed region.
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18
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Bryant SJ, Vernerey FJ. Programmable Hydrogels for Cell Encapsulation and Neo-Tissue Growth to Enable Personalized Tissue Engineering. Adv Healthc Mater 2018; 7. [PMID: 28975716 DOI: 10.1002/adhm.201700605] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 06/12/2017] [Indexed: 12/11/2022]
Abstract
Biomimetic and biodegradable synthetic hydrogels are emerging as a promising platform for cell encapsulation and tissue engineering. Notably, synthetic-based hydrogels offer highly programmable macroscopic properties (e.g., mechanical, swelling and transport properties) and degradation profiles through control over several tunable parameters (e.g., the initial network structure, degradation kinetics and behavior, and polymer properties). One component to success is the ability to maintain structural integrity as the hydrogel transitions to neo-tissue. This seamless transition is complicated by the fact that cellular activity is highly variable among donors. Thus, computational models provide an important tool in tissue engineering due to their unique ability to explore the coupled processes of hydrogel degradation and neo-tissue growth across multiple length scales. In addition, such models provide new opportunities to develop predictive computational tools to overcome the challenges with designing hydrogels for different donors. In this report, programmable properties of synthetic-based hydrogels and their relation to the hydrogel's structural properties and their evolution with degradation are reviewed. This is followed by recent progress on the development of computational models that describe hydrogel degradation with neo-tissue growth when cells are encapsulated in a hydrogel. Finally, the potential for predictive models to enable patient-specific hydrogel designs for personalized tissue engineering is discussed.
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Affiliation(s)
- Stephanie J. Bryant
- Department of Chemical and Biological Engineering; University of Colorado; 3415 Colorado Ave; Boulder CO 80309-0596 USA
| | - Franck J. Vernerey
- Department of Mechanical Engineering; University of Colorado; 1111 Engineering Dr.; Boulder CO 80309-0428 USA
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19
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Chen A, He H, Ma G, Li Y, Jiang S, Xuan X, Song Y, Zhang C, Xiao J, Xu Y, Wu J, Chen S. Biodegradable copolypeptide hydrogel prodrug accelerates dermal wound regeneration by enhanced angiogenesis and epithelialization. RSC Adv 2018; 8:10620-10626. [PMID: 35540456 PMCID: PMC9078897 DOI: 10.1039/c8ra00401c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 03/01/2018] [Indexed: 12/25/2022] Open
Abstract
Hydrogels are one of the most promising wound dressings. However, their effectiveness on wound healing is still largely limited due to either the non-degradability or the release of non-therapeutic degradable products. Herein, a biodegradable copolypeptide hydrogel based on the glutamic acid and lysine was synthesized and applied as both wound dressing and therapeutic prodrug. The hydrogel can degrade in the existence of elevated degradative enzymes in a wound environment, which will release therapeutic amino acids to enhance the wound healing. In vivo results found that the hydrogel could effectively promote wound regeneration in both macroscopic and microscopic scales. Further investigation revealed that the wound healing effect of the hydrogel was highly attributed to its enhanced impact on angiogenesis, cell proliferation and re-epithelialization of the wound. All in all, the present study proves that the degradable copolypeptide hydrogel can efficiently improve wound healing and indicates its potent clinical application for wound regeneration. Biodegradable hydrogel as a wound dressing and therapeutic prodrug promoting wound regeneration through enhanced angiogenesis and epithelialization.![]()
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Affiliation(s)
- Anqi Chen
- The First Affiliated Hospital of Wenzhou Medical University
- Wenzhou
- P. R. China
- Wenzhou Medical University
- Wenzhou
| | | | | | - Yi Li
- Wenzhou Medical University
- Wenzhou
- P. R. China
| | | | - Xuan Xuan
- Wenzhou Medical University
- Wenzhou
- P. R. China
| | - Yi Song
- Wenzhou Medical University
- Wenzhou
- P. R. China
| | | | - Jian Xiao
- Wenzhou Medical University
- Wenzhou
- P. R. China
| | - Yunsheng Xu
- The First Affiliated Hospital of Wenzhou Medical University
- Wenzhou
- P. R. China
- Wenzhou Medical University
- Wenzhou
| | - Jiang Wu
- The First Affiliated Hospital of Wenzhou Medical University
- Wenzhou
- P. R. China
- Wenzhou Medical University
- Wenzhou
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20
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Shaw N, Erickson C, Bryant SJ, Ferguson VL, Krebs MD, Hadley-Miller N, Payne KA. Regenerative Medicine Approaches for the Treatment of Pediatric Physeal Injuries. TISSUE ENGINEERING PART B-REVIEWS 2017; 24:85-97. [PMID: 28830302 DOI: 10.1089/ten.teb.2017.0274] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The physis, or growth plate, is a cartilaginous region at the end of children's long bones that serves as the primary center for longitudinal growth and characterizes the immature skeleton. Musculoskeletal injury, including fracture, infection, malignancy, or iatrogenic damage, has risk of physeal damage. Physeal injuries account for 30% of pediatric fractures and may result in impaired bone growth. Once damaged, cartilage tissue within the physis is often replaced by unwanted bony tissue, forming a "bony bar" that can lead to complications such as complete growth arrest, angular or rotational deformities, and altered joint mechanics. Children with a bony bar occupying <50% of the physis usually undergo bony bar resection and insertion of an interpositional material, such as a fat graft, to prevent recurrence and allow the surrounding uninjured physeal tissue to restore longitudinal bone growth. Clinical success for this procedure is <35% and often the bony bar and associated growth impairments return. Children who are not candidates for bony bar resection due to a physeal bar occupying >50% of their physis undergo corrective osteotomy or bone lengthening procedures. These approaches are complex and have variable success rates. As such, there is a critical need for regenerative approaches to not only prevent initial bony bar formation but also regenerate healthy physeal cartilage following injury. This review describes physeal anatomy, mechanisms of physeal injury, and current treatment options with associated limitations. Furthermore, we provide an overview of the current research using cell-based therapies, growth factors, and biomaterials in the different animal models of injury along with strategic directions for modulating intrinsic injury pathways to inhibit bony bar formation and/or promote physeal tissue formation. Pediatric physeal injuries constitute a unique niche within regenerative medicine for which there is a critical need for research to decrease child morbidity related to this injurious process.
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Affiliation(s)
- Nichole Shaw
- 1 Department of Orthopedics, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Christopher Erickson
- 1 Department of Orthopedics, University of Colorado Anschutz Medical Campus , Aurora, Colorado.,2 Department of Bioengineering, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Stephanie J Bryant
- 3 Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado.,4 BioFrontiers Institute, University of Colorado Boulder , Boulder, Colorado.,5 Material Science and Engineering Program, University of Colorado Boulder , Boulder, Colorado
| | - Virginia L Ferguson
- 4 BioFrontiers Institute, University of Colorado Boulder , Boulder, Colorado.,5 Material Science and Engineering Program, University of Colorado Boulder , Boulder, Colorado.,6 Department of Mechanical Engineering, University of Colorado Boulder , Boulder, Colorado
| | - Melissa D Krebs
- 7 Department of Chemical and Biological Engineering, Colorado School of Mines , Golden, Colorado.,8 Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Nancy Hadley-Miller
- 1 Department of Orthopedics, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Karin A Payne
- 1 Department of Orthopedics, University of Colorado Anschutz Medical Campus , Aurora, Colorado.,8 Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus , Aurora, Colorado
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