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Brunel LG, Christakopoulos F, Kilian D, Cai B, Hull SM, Myung D, Heilshorn SC. Embedded 3D Bioprinting of Collagen Inks into Microgel Baths to Control Hydrogel Microstructure and Cell Spreading. Adv Healthc Mater 2023:e2303325. [PMID: 38134346 DOI: 10.1002/adhm.202303325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/14/2023] [Indexed: 12/24/2023]
Abstract
Microextrusion-based 3D bioprinting into support baths has emerged as a promising technique to pattern soft biomaterials into complex, macroscopic structures. It is hypothesized that interactions between inks and support baths, which are often composed of granular microgels, can be modulated to control the microscopic structure within these macroscopic-printed constructs. Using printed collagen bioinks crosslinked either through physical self-assembly or bioorthogonal covalent chemistry, it is demonstrated that microscopic porosity is introduced into collagen inks printed into microgel support baths but not bulk gel support baths. The overall porosity is governed by the ratio between the ink's shear viscosity and the microgel support bath's zero-shear viscosity. By adjusting the flow rate during extrusion, the ink's shear viscosity is modulated, thus controlling the extent of microscopic porosity independent of the ink composition. For covalently crosslinked collagen, printing into support baths comprised of gelatin microgels (15-50 µm) results in large pores (≈40 µm) that allow human corneal mesenchymal stromal cells (MSCs) to readily spread, while control samples of cast collagen or collagen printed in non-granular support baths do not allow cell spreading. Taken together, these data demonstrate a new method to impart controlled microscale porosity into 3D printed hydrogels using granular microgel support baths.
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Affiliation(s)
- Lucia G Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Fotis Christakopoulos
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - David Kilian
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Betty Cai
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - David Myung
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, 94303, USA
- VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
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Seymour AJ, Kilian D, Navarro RS, Hull SM, Heilshorn SC. 3D printing microporous scaffolds from modular bioinks containing sacrificial, cell-encapsulating microgels. Biomater Sci 2023; 11:7598-7615. [PMID: 37824082 PMCID: PMC10842430 DOI: 10.1039/d3bm00721a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Microgel-based biomaterials have inherent porosity and are often extrudable, making them well-suited for 3D bioprinting applications. Cells are commonly introduced into these granular inks post-printing using cell infiltration. However, due to slow cell migration speeds, this strategy struggles to achieve depth-independent cell distributions within thick 3D printed geometries. To address this, we leverage granular ink modularity by combining two microgels with distinct functions: (1) structural, UV-crosslinkable microgels made from gelatin methacryloyl (GelMA) and (2) sacrificial, cell-laden microgels made from oxidized alginate (AlgOx). We hypothesize that encapsulating cells within sacrificial AlgOx microgels would enable the simultaneous introduction of void space and release of cells at depths unachievable through cell infiltration alone. Blending the microgels in different ratios produces a family of highly printable GelMA : AlgOx microgel inks with void fractions ranging from 0.03 to 0.35. As expected, void fraction influences the morphology of human umbilical vein endothelial cells (HUVEC) within GelMA : AlgOx inks. Crucially, void fraction does not alter the ideal HUVEC distribution seen throughout the depth of 3D printed samples. This work presents a strategy for fabricating constructs with tunable porosity and depth-independent cell distribution, highlighting the promise of microgel-based inks for 3D bioprinting.
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Affiliation(s)
- Alexis J Seymour
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - David Kilian
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Renato S Navarro
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Sarah C Heilshorn
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA.
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Hull SM, Lou J, Lindsay CD, Navarro RS, Cai B, Brunel LG, Westerfield AD, Xia Y, Heilshorn SC. 3D bioprinting of dynamic hydrogel bioinks enabled by small molecule modulators. Sci Adv 2023; 9:eade7880. [PMID: 37000873 PMCID: PMC10065439 DOI: 10.1126/sciadv.ade7880] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 02/24/2023] [Indexed: 06/19/2023]
Abstract
Three-dimensional bioprinting has emerged as a promising tool for spatially patterning cells to fabricate models of human tissue. Here, we present an engineered bioink material designed to have viscoelastic mechanical behavior, similar to that of living tissue. This viscoelastic bioink is cross-linked through dynamic covalent bonds, a reversible bond type that allows for cellular remodeling over time. Viscoelastic materials are challenging to use as inks, as one must tune the kinetics of the dynamic cross-links to allow for both extrudability and long-term stability. We overcome this challenge through the use of small molecule catalysts and competitors that temporarily modulate the cross-linking kinetics and degree of network formation. These inks were then used to print a model of breast cancer cell invasion, where the inclusion of dynamic cross-links was found to be required for the formation of invasive protrusions. Together, we demonstrate the power of engineered, dynamic bioinks to recapitulate the native cellular microenvironment for disease modeling.
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Affiliation(s)
- Sarah M. Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Junzhe Lou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | | | - Renato S. Navarro
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Betty Cai
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Lucia G. Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | | | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Sarah C. Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
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Cable J, Arlotta P, Parker KK, Hughes AJ, Goodwin K, Mummery CL, Kamm RD, Engle SJ, Tagle DA, Boj SF, Stanton AE, Morishita Y, Kemp ML, Norfleet DA, May EE, Lu A, Bashir R, Feinberg AW, Hull SM, Gonzalez AL, Blatchley MR, Montserrat Pulido N, Morizane R, McDevitt TC, Mishra D, Mulero-Russe A. Engineering multicellular living systems-a Keystone Symposia report. Ann N Y Acad Sci 2022; 1518:183-195. [PMID: 36177947 PMCID: PMC9771928 DOI: 10.1111/nyas.14896] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The ability to engineer complex multicellular systems has enormous potential to inform our understanding of biological processes and disease and alter the drug development process. Engineering living systems to emulate natural processes or to incorporate new functions relies on a detailed understanding of the biochemical, mechanical, and other cues between cells and between cells and their environment that result in the coordinated action of multicellular systems. On April 3-6, 2022, experts in the field met at the Keystone symposium "Engineering Multicellular Living Systems" to discuss recent advances in understanding how cells cooperate within a multicellular system, as well as recent efforts to engineer systems like organ-on-a-chip models, biological robots, and organoids. Given the similarities and common themes, this meeting was held in conjunction with the symposium "Organoids as Tools for Fundamental Discovery and Translation".
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Affiliation(s)
| | - Paola Arlotta
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Kevin Kit Parker
- Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
- Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts, USA
| | - Alex J Hughes
- Department of Bioengineering, School of Engineering and Applied Science and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Katharine Goodwin
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA
| | - Christine L Mummery
- Department of Anatomy and Embryology and LUMC hiPSC Hotel, Leiden University Medical Center, Leiden, the Netherlands
| | - Roger D Kamm
- Department of Mechanical Engineering and Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sandra J Engle
- Translational Biology, Biogen, Cambridge, Massachusetts, USA
| | - Danilo A Tagle
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, USA
| | - Sylvia F Boj
- Hubrecht Organoid Technology (HUB), Utrecht, the Netherlands
| | - Alice E Stanton
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Yoshihiro Morishita
- Laboratory for Developmental Morphogeometry, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO) Program, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Melissa L Kemp
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
| | - Dennis A Norfleet
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
| | - Elebeoba E May
- Department of Biomedical Engineering and HEALTH Research Institute, University of Houston, Houston, Texas, USA
- Wisconsin Institute of Discovery and Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Aric Lu
- Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
- Draper Laboratory, Biological Engineering Division, Cambridge, Massachusetts, USA
| | - Rashid Bashir
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois, USA
- Holonyak Micro & Nanotechnology Laboratory, Department of Electrical and Computer Engineering and Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Adam W Feinberg
- Department of Biomedical Engineering and Department of Materials Science & Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, California, USA
| | - Anjelica L Gonzalez
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Michael R Blatchley
- BioFrontiers Institute and Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado, USA
| | | | - Ryuji Morizane
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Todd C McDevitt
- The Gladstone Institutes and Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, USA
| | - Deepak Mishra
- Department of Biological Engineering, Synthetic Biology Center, Cambridge, Massachusetts, USA
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Adriana Mulero-Russe
- Parker H. Petit Institute for Bioengineering and Bioscience and School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
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Brunel LG, Hull SM, Heilshorn SC. Engineered assistive materials for 3D bioprinting: support baths and sacrificial inks. Biofabrication 2022; 14:032001. [PMID: 35487196 PMCID: PMC10788121 DOI: 10.1088/1758-5090/ac6bbe] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/29/2022] [Indexed: 11/11/2022]
Abstract
Three-dimensional (3D) bioprinting is a promising technique for spatially patterning cells and materials into constructs that mimic native tissues and organs. However, a trade-off exists between printability and biological function, where weak materials are typically more suited for 3D cell culture but exhibit poor shape fidelity when printed in air. Recently, a new class of assistive materials has emerged to overcome this limitation and enable fabrication of more complex, biologically relevant geometries, even when using soft materials as bioinks. These materials include support baths, which bioinks are printed into, and sacrificial inks, which are printed themselves and then later removed. Support baths are commonly yield-stress materials that provide physical confinement during the printing process to improve resolution and shape fidelity. Sacrificial inks have primarily been used to create void spaces and pattern perfusable networks, but they can also be combined directly with the bioink to change its mechanical properties for improved printability or increased porosity. Here, we outline the advantages of using such assistive materials in 3D bioprinting, define their material property requirements, and offer case study examples of how these materials are used in practice. Finally, we discuss the remaining challenges and future opportunities in the development of assistive materials that will propel the bioprinting field forward toward creating full-scale, biomimetic tissues and organs.
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Affiliation(s)
- Lucia G Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA, United States of America
| | - Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA, United States of America
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, United States of America
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Hull SM, Brunel LG, Heilshorn SC. 3D Bioprinting of Cell-Laden Hydrogels for Improved Biological Functionality. Adv Mater 2022; 34:e2103691. [PMID: 34672027 PMCID: PMC8988886 DOI: 10.1002/adma.202103691] [Citation(s) in RCA: 62] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 09/15/2021] [Indexed: 05/03/2023]
Abstract
The encapsulation of cells within gel-phase materials to form bioinks offers distinct advantages for next-generation 3D bioprinting. 3D bioprinting has emerged as a promising tool for patterning cells, but the technology remains limited in its ability to produce biofunctional, tissue-like constructs due to a dearth of materials suitable for bioinks. While early demonstrations commonly used viscous polymers optimized for printability, these materials often lacked cell compatibility and biological functionality. In response, advanced materials that exist in the gel phase during the entire printing process are being developed, since hydrogels are uniquely positioned to both protect cells during extrusion and provide biological signals to embedded cells as the construct matures during culture. Here, an overview of the design considerations for gel-phase materials as bioinks is presented, with a focus on their mechanical, biochemical, and dynamic gel properties. Current challenges and opportunities that arise due to the fact that bioprinted constructs are active, living hydrogels composed of both acellular and cellular components are also evaluated. Engineering hydrogels with consideration of cells as an intrinsic component of the printed bioink will enable control over the evolution of the living construct after printing to achieve greater biofunctionality.
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Affiliation(s)
- Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Lucia G Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
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Hull SM, Lindsay CD, Brunel LG, Shiwarski DJ, Tashman JW, Roth JG, Myung D, Feinberg AW, Heilshorn SC. 3D Bioprinting using UNIversal Orthogonal Network (UNION) Bioinks. Adv Funct Mater 2021; 31:2007983. [PMID: 33613150 PMCID: PMC7888563 DOI: 10.1002/adfm.202007983] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Indexed: 05/02/2023]
Abstract
Three-dimensional (3D) bioprinting is a promising technology to produce tissue-like structures, but a lack of diversity in bioinks is a major limitation. Ideally each cell type would be printed in its own customizable bioink. To fulfill this need for a universally applicable bioink strategy, we developed a versatile, bioorthogonal bioink crosslinking mechanism that is cell compatible and works with a range of polymers. We term this family of materials UNIversal, Orthogonal Network (UNION) bioinks. As demonstration of UNION bioink versatility, gelatin, hyaluronic acid (HA), recombinant elastin-like protein (ELP), and polyethylene glycol (PEG) were each used as backbone polymers to create inks with storage moduli spanning 200 to 10,000 Pa. Because UNION bioinks are crosslinked by a common chemistry, multiple materials can be printed together to form a unified, cohesive structure. This approach is compatible with any support bath that enables diffusion of UNION crosslinkers. Both matrix-adherent human corneal mesenchymal stromal cells and non-matrix-adherent human induced pluripotent stem cell-derived neural progenitor spheroids were printed with UNION bioinks. The cells retained high viability and expressed characteristic phenotypic markers after printing. Thus, UNION bioinks are a versatile strategy to expand the toolkit of customizable materials available for 3D bioprinting.
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Affiliation(s)
- Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Christopher D Lindsay
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA
| | - Lucia G Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Daniel J Shiwarski
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Joshua W Tashman
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Julien G Roth
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - David Myung
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Adam W Feinberg
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Sarah C Heilshorn
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA
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Lee HJ, Fernandes‐Cunha GM, Na K, Hull SM, Myung D. Bio-Orthogonally Crosslinked, In Situ Forming Corneal Stromal Tissue Substitute. Adv Healthc Mater 2018; 7:e1800560. [PMID: 30106514 DOI: 10.1002/adhm.201800560] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/18/2018] [Indexed: 12/13/2022]
Abstract
In this study, an in situ forming corneal stromal substitute based on collagen type I crosslinked by bio-orthogonal strain-promoted azide-alkyne cycloaddition (SPAAC) is presented. The crosslinked collagen gel has greater transparency compared to non-crosslinked collagen gels. The mechanical properties of the gels are controlled by changing functional group ratios and conjugated collagen concentrations. Higher concentrations of conjugated collagen yield enhances mechanical properties, where the storage modulus increases from 42.39 ± 8.95 to 112.03 ± 3.94 Pa after SPAAC crosslinking. Encapsulated corneal keratocytes grow within the SPAAC-crosslinked gels and corneal keratinocytes are supported on top of the gel surfaces. SPAAC-crosslinked gels support more favorable and stable keratinocyte morphology on their surface compared to non-crosslinked gels likely as a result of more optimal substrate stiffness, gel integrity, and resistance to degradation. SPAAC-crosslinked collagen gels with and without encapsulated keratocytes applied to rabbit corneas in an organ culture model after keratectomy exhibit surface epithelialization with multilayered morphology. The novel in situ forming gel is a promising candidate for lamellar and defect reconstruction of corneal stromal tissue.
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Affiliation(s)
- Hyun Jong Lee
- Byers Eye Institute at Stanford University School of Medicine Palo Alto CA 94303 USA
| | | | - Kyung‐Sun Na
- Byers Eye Institute at Stanford University School of Medicine Palo Alto CA 94303 USA
- Department of Ophthalmology and Visual Science Yeouido St. Mary's Hospital College of Medicine The Catholic University of Korea Seoul 07345 South Korea
| | - Sarah M. Hull
- Department of Chemical Engineering Stanford University Stanford CA 94305 USA
| | - David Myung
- Byers Eye Institute at Stanford University School of Medicine Palo Alto CA 94303 USA
- VA Palo Alto Health Care System Palo Alto CA 94304 USA
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Goodfield M, Hull SM, Holland D, Roberts G, Wood E, Reid S, Cunliffe W. Investigations of the 'active' edge of plaque psoriasis: vascular proliferation precedes changes in epidermal keratin. Br J Dermatol 1994; 131:808-13. [PMID: 7532001 DOI: 10.1111/j.1365-2133.1994.tb08582.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have investigated markers of epidermal proliferation and differentiation in terms of keratin expression, the morphology of the cutaneous vasculature, and numbers of cutaneous mast cells, in patients with chronic plaque psoriasis. Using the phenomenon of the 'active edge', we have studied these features in the psoriatic plaque itself, and in the clinically normal active and inactive edges of the same plaque. Our results confirm the anticipated changes in keratin profiles, mast cell numbers and psoriatic morphology of the vasculature within the plaque itself. They further indicate that the vascular changes precede the epidermal and mast cell features at the active edge, and that the inactive edge is inactive for all of these variables. Mediators responsible for the vascular proliferation and elongation must be present in increased amounts at the active edge when compared with the inactive, and include locally produced and circulating factors.
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Affiliation(s)
- M Goodfield
- Department of Dermatology, Leeds General Infirmary, U.K
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Abstract
We have investigated the systemic effect of local treatment with dithranol for one week in psoriasis by a combination of subjective assessment of the severity of individual plaques and more objective assessment of blood flow (measured by laser-Doppler flowmetry) of the centre of the plaque, and at the active edge of the plaque. There is both subjective and objective evidence of an improvement in untreated plaques of psoriasis when dithranol is used on plaques elsewhere on the body. Blood flow falls at the active edge and at the centre of the plaques that are untreated. These findings indicate a systemic effect of local treatment that is more likely to be due to circulating factors, possibly T cells, rather than a direct effect of circulating dithranol. They also suggest that within patient comparisons of topical treatment in psoriasis may be inaccurate.
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Affiliation(s)
- M J Goodfield
- Department of Dermatology, General Infirmary, Leeds, U.K
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Abstract
The relationship between sebum excretion rate (SER) and clinical improvement was investigated in 255 acne patients treated for 6 months with either oral erythromycin (1 g/day), minocycline (100 mg/day), oxytetracycline (1 g/day) or cotrimoxazole (400 mg/day); topical therapy was 5% benzoyl peroxide. In all but the cotrimoxazole treated group, there was a significant correlation between a high SER and reduced clinical response. This was particularly evident in those patients with an SER of greater than 2.5 micrograms/cm2/min. These patients showed only 17% improvement compared with 100% improvement in those subjects with an SER of 1.0 micrograms/cm2/min or less. The presence of obvious seborrhoea in a patient who has failed to respond to an adequate 6-month course of antimicrobial therapy, should indicate the earlier rather than later use of isotretinoin for their acne.
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Affiliation(s)
- A M Layton
- Department of Dermatology, General Infirmary at Leeds, UK
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Hull SM, Nutbrown M, Thornton MJ, Cunliffe WJ, Randall VA. Evidence for a subclinical state of alopecia areata. Ann N Y Acad Sci 1991; 642:478-9. [PMID: 1809112 DOI: 10.1111/j.1749-6632.1991.tb24424.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- S M Hull
- Department of Dermatology, Leeds General Infirmary, United Kingdom
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Nutbrown M, Hull SM, Thornton MJ, Cunliffe WJ, Randall VA. The ultrastructure of the dermal papilla-epithelial junction in normal and alopecia areata hair follicles. Ann N Y Acad Sci 1991; 642:476-7. [PMID: 1809111 DOI: 10.1111/j.1749-6632.1991.tb24423.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M Nutbrown
- Department of Biomedical Sciences, University of Bradford, United Kingdom
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Abstract
Twelve children with extensive alopecia areata or alopecia totalis were treated with the contact allergen diphencyprone. The duration of treatment ranged from 5 months to 1 year. Eight of the 12 (67%) regrew scalp hair and in four (33%) there was a complete regrowth. Six months after treatment was discontinued three of the four children with complete regrowth maintained their hair, one had lost all the regrowth and a further child with patchy regrowth at the end of treatment subsequently regrew hair completely while off therapy.
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Affiliation(s)
- S M Hull
- Leeds Foundation for Dermatological Research, General Infirmary, Leeds, U.K
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Abstract
Sixteen patients with minimal facial acne but with symptoms of dysmorphophobia related to their acne were treated with isotretinoin, 0.5 mg/kg/day, (n = 5); 1 mg/kg/day (n = 11) for 16 weeks. All 16 had previously received long-term antibiotic therapy with no 'perceived' improvement in their acne. Formal psychiatric assessment was not possible through lack of cooperation. Fourteen of 16 patients derived benefit from isotretinoin therapy in that all 14 were subsequently satisfied with the cosmetic results achieved. However, the incidence of relapse was greater than that for a control group, 14 requiring additional therapy in the form of antibiotics or further isotretinoin (seven patients) within 20 months of completing the original course. Patients with acne and dysmorphophobia represent an important group of patients who benefit from treatment with isotretinoin; if possible this should be in conjunction with psychotherapy.
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Affiliation(s)
- S M Hull
- Leeds Foundation for Dermatological Research, General Infirmary, Leeds, UK
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Hull SM, Nutbrown M, Pepall L, Thornton MJ, Randall VA, Cunliffe WJ. Immunohistologic and ultrastructural comparison of the dermal papilla and hair follicle bulb from "active" and "normal" areas of alopecia areata. J Invest Dermatol 1991; 96:673-81. [PMID: 1827135 DOI: 10.1111/1523-1747.ep12470601] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The "active" edges of patches of alopecia areata and normal areas from the same scalp (i.e., bearing normal terminal hair) from seven patients with alopecia areata were investigated immunohistologically. Similar areas from a further eight patients were examined using light and electronmicroscopy. "Active" and "normal" areas of alopecia areata scalps were immunohistologically similar and varied from normal controls in the number, distribution, and ratio for T4 and T8-positive cells. Similarly the ultrastructural changes seen in the "active" areas when compared to normal controls were also present in the "normal" areas of alopecia areata scalps. The most significant differences found between normal "control" follicles and both "active" and "normal" areas of alopecia areata scalps were the polymorphic nature of the dermal papilla cells and the loss of cellular organization within the dermal papillae taken from alopecia areata scalps. In addition, the junction between the dermal papilla and the bulb of the hair follicle, the dermo-epithelial junction of the hair follicle bulb, demonstrated critical changes in follicles taken from both "active" and "normal" areas of alopecia areata scalps. These results support the suggestion of a subclinical state of alopecia areata and indicate that further work on the etiology of alopecia areata should be directed towards the "normal" areas of alopecia areata scalps, in particular the cells of the dermal papilla and the dermo-epithelial junction of the hair follicle bulb.
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Affiliation(s)
- S M Hull
- Department of Dermatology, General Infirmary, Leeds, England
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Hull SM, Goodfield M, Wood EJ, Cunliffe WJ. Active and inactive edges of psoriatic plaques: identification by tracing and investigation by laser--Doppler flowmetry and immunocytochemical techniques. J Invest Dermatol 1989; 92:782-5. [PMID: 2656871 DOI: 10.1111/1523-1747.ep12696791] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In plaque psoriasis it is likely that biochemical and ultrastructural changes precede the appearance of the typical plaque that is recognizable clinically. Currently, no technique exists by which the very early changes in psoriasis can be investigated. We report a method in which plaques of psoriasis are serially traced to identify their advancing edge. Eight-two untreated plaques from 15 patients and 38 treated plaques from 6 patients were traced over a three-week period; 65% of untreated and 57% of treated plaques showed consistent asymmetrical movement, allowing identification of an active and an inactive edge of each plaque. Using this technique, the active edge of two or more plaques was identified in each of ten patients. Blood flow measured by laser Doppler flowmetry indicated a 2.5-to-4.5-fold increase in cutaneous blood flow at the active edge compared with the inactive edge of each plaque. Punch biopsies from the sites investigated by laser Doppler flowmetry were examined by routine histology and monoclonal antibody immunohistology, but revealed no epidermal change and no T lymphocytic excess when the two areas were compared. We infer from these findings that the earliest change in a developing plaque is an increased blood flow, probably associated with a diffusable, and possibly humoral, initiating factor that accumulates at the active edge, stimulating transformation of normal skin to psoriatic plaque.
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Affiliation(s)
- S M Hull
- Department of Dermatology, Leeds General Infirmary, U.K
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Abstract
Thirty-six patients with alopecia areata of 1-54 years duration entered a study of treatment with the contact allergen diphencyprone for 8 months. Following sensitization the diphencyprone was applied to one half of the scalp at weekly intervals, the other half acting as a control. Once hair growth was established on one side, the other side was treated. Seven patients did not continue treatment and one patient showed spontaneous regrowth. Of the remaining 28 patients who persisted with treatments, fourteen (50%) regrew hair on the treated side; eight (29%) had a cosmetically acceptable result with the regrowth of terminal hair over the whole scalp. No statistically significant differences were found in age or duration of alopecia between those who regrew and those who did not. We have found diphencyprone to be an effective stimulator of hair growth in patients with severe and long-standing alopecia areata.
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Affiliation(s)
- S M Hull
- Department of Dermatology, General Infirmary, Leeds, U.K
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Abstract
All 24 patients on long-term digoxin in a general practice were reviewed. 17 of the 18 patients in sinus rhythm had their digoxin discontinued without any alteration in their cardiovascular signs or symptoms. Other therapy was adjusted as necessary. These results suggest that heart-failure can often be managed without long-term digoxin therapy.
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