1
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Olevsky LM, Anup A, Jacques M, Keokominh N, Holmgren EP, Hixon KR. Direct Integration of 3D Printing and Cryogel Scaffolds for Bone Tissue Engineering. Bioengineering (Basel) 2023; 10:889. [PMID: 37627774 PMCID: PMC10451777 DOI: 10.3390/bioengineering10080889] [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: 06/30/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
Cryogels, known for their biocompatibility and porous structure, lack mechanical strength, while 3D-printed scaffolds have excellent mechanical properties but limited porosity resolution. By combining a 3D-printed plastic gyroid lattice scaffold with a chitosan-gelatin cryogel scaffold, a scaffold can be created that balances the advantages of both fabrication methods. This study compared the pore diameter, swelling potential, mechanical characteristics, and cellular infiltration capability of combined scaffolds and control cryogels. The incorporation of the 3D-printed lattice demonstrated patient-specific geometry capabilities and significantly improved mechanical strength compared to the control cryogel. The combined scaffolds exhibited similar porosity and relative swelling ratio to the control cryogels. However, they had reduced elasticity, reduced absolute swelling capacity, and are potentially cytotoxic, which may affect their performance. This paper presents a novel approach to combine two scaffold types to retain the advantages of each scaffold type while mitigating their shortcomings.
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Affiliation(s)
- Levi M. Olevsky
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; (L.M.O.); (A.A.)
| | - Amritha Anup
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; (L.M.O.); (A.A.)
| | - Mason Jacques
- College of Engineering and Physical Sciences, University of New Hampshire, Durham, NH 03824, USA; (M.J.); (N.K.)
| | - Nadia Keokominh
- College of Engineering and Physical Sciences, University of New Hampshire, Durham, NH 03824, USA; (M.J.); (N.K.)
| | - Eric P. Holmgren
- Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA;
| | - Katherine R. Hixon
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; (L.M.O.); (A.A.)
- Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA;
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2
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Chen T, McCarthy MM, Guo H, Warren R, Maher SA. The Scaffold-Articular Cartilage Interface: A Combined In Vitro and In Silico Analysis Under Controlled Loading Conditions. J Biomech Eng 2019; 140:2680997. [PMID: 29801169 DOI: 10.1115/1.4040121] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Indexed: 12/25/2022]
Abstract
The optimal method to integrate scaffolds with articular cartilage has not yet been identified, in part because of our lack of understanding about the mechanobiological conditions at the interface. Our objective was to quantify the effect of mechanical loading on integration between a scaffold and articular cartilage. We hypothesized that increased number of loading cycles would have a detrimental effect on interface integrity. The following models were developed: (i) an in vitro scaffold-cartilage explant system in which compressive sinusoidal loading cycles were applied for 14 days at 1 Hz, 5 days per week, for either 900, 1800, 3600, or 7200 cycles per day and (ii) an in silico inhomogeneous, biphasic finite element model (bFEM) of the scaffold-cartilage construct that was used to characterize interface micromotion, stress, and fluid flow under the prescribed loading conditions. In accordance with our hypothesis, mechanical loading significantly decreased scaffold-cartilage interface strength compared to unloaded controls regardless of the number of loading cycles. The decrease in interfacial strength can be attributed to abrupt changes in vertical displacement, fluid pressure, and compressive stresses along the interface, which reach steady-state after only 150 cycles of loading. The interfacial mechanical conditions are further complicated by the mismatch between the homogeneous properties of the scaffold and the depth-dependent properties of the articular cartilage. Finally, we suggest that mechanical conditions at the interface can be more readily modulated by increasing pre-incubation time before the load is applied, as opposed to varying the number of loading cycles.
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Affiliation(s)
- Tony Chen
- Department of Biomechanics and Orthopedic Soft Tissue Research Program, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 e-mail:
| | - Moira M McCarthy
- Sports Medicine and Shoulder Service, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 e-mail:
| | - Hongqiang Guo
- Department of Biomechanics and Orthopedic Soft Tissue Research Program, Hospital for Special Surgery, th , New York, NY 10021 e-mail:
| | - Russell Warren
- Sports Medicine and Shoulder Service, Hospital for Special Surgery, th , New York, NY 10021 e-mail:
| | - Suzanne A Maher
- Department of Biomechanics and Orthopedic Soft Tissue Research Program, Hospital for Special Surgery, th , New York, NY 10021 e-mail:
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3
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Fuchs J, Mueller M, Daxböck C, Stückler M, Lang I, Leitinger G, Bock E, El-Heliebi A, Moser G, Glasmacher B, Brislinger D. Histological processing of un-/cellularized thermosensitive electrospun scaffolds. Histochem Cell Biol 2018; 151:343-356. [PMID: 30560287 PMCID: PMC6469612 DOI: 10.1007/s00418-018-1757-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2018] [Indexed: 11/28/2022]
Abstract
Histological processing of thermosensitive electrospun poly(ε-caprolactone)/poly(l-lactide) (PCL/PLA) scaffolds fails, as poly(ε-caprolactone) (PCL) is characterized by its low-melting temperature (Tm = 60 °C). Here, we present an optimized low-temperature preparation method for the histological processing of un-/cellularized thermosensitive PCL/PLA scaffolds. Our study is aimed at the establishment of an optimized dehydration and low-melting-point paraffin-embedding method of electrospun PCL/PLA scaffolds (un-/cellularized). Furthermore, we compared this method with (a) automatized dehydration and standard paraffin embedding, (b) gelatin embedding followed by automatized dehydration and standard paraffin embedding, (c) cryofixation, and (d) acrylic resin embedding methods. We investigated pepsin and proteinase K antigen retrieval for their efficiency in epitope demasking at low temperatures and evaluated protocols for immunohistochemistry and immunofluorescence for cytokeratin 7 (CK7) and in situ padlock probe technology for beta actin (ACTB). Optimized dehydration and low-melting-point paraffin embedding preserved the PCL/PLA scaffold, as the diameter and structure of its fibers were unchanged. Cells attached to the PCL/PLA scaffolds showed limited alterations in size and morphology compared to control. Epitope demasking by enzymatic pepsin digestion and immunostaining of CK7 displayed an invasion of attached cells into the scaffold. Expression of ACTB and CK7 was shown by a combination of mRNA-based in situ padlock probe technology and immunofluorescence. In contrast, gelatin stabilization followed by standard paraffin embedding led to an overall shrinkage and melting of fibers, and therefore, no further analysis was possible. Acrylic resin embedding and cyrofixation caused fiber structures that were nearly unchanged in size and diameter. However, acrylic resin-embedded scaffolds are limited to 3 µm sections, whereas cyrofixation led to a reduction of the cell size by 14% compared to low-melting paraffin embedding. The combination of low-melting-point paraffin embedding and pepsin digestion as an antigen retrieval method offers a successful opportunity for histological investigations in thermosensitive specimens.
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Affiliation(s)
- Julia Fuchs
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Marc Mueller
- Institute for Multiphase Processes, Leibniz University Hannover, Callinstraße 36, 30167, Hannover, Germany
| | - Christine Daxböck
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Manuela Stückler
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Ingrid Lang
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Gerd Leitinger
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Elisabeth Bock
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Amin El-Heliebi
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Gerit Moser
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria
| | - Birgit Glasmacher
- Institute for Multiphase Processes, Leibniz University Hannover, Callinstraße 36, 30167, Hannover, Germany
| | - Dagmar Brislinger
- Department of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6, 8010, Graz, Austria.
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4
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Ushida K, Asai N, Uchiyama K, Enomoto A, Takahashi M. Development of a method to preliminarily embed tissue samples using low melting temperature fish gelatin before sectioning: A technical note. Pathol Int 2018; 68:241-245. [PMID: 29465759 DOI: 10.1111/pin.12652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/19/2018] [Indexed: 11/28/2022]
Abstract
Embedding of tissue samples that maintains a desired orientation is critical for preparing sections suitable for diagnosis and study objectives. Methods to prepare tissue sections include: (i) paraffin embedding or snap-freezing followed by microtome or cryostat sectioning; and (ii) agarose embedding followed by cutting on a vibrating microslicer. Although these methods are useful for routine laboratory work, preparation of small and fragile tissues such as mouse organs, small human biopsy samples, and cultured floating spheres is difficult and requires special skills. In particular, tissue specimen orientation can be lost during embedding in molds and subsequent sectioning. Here, we developed a method using low melting temperature (LM) gelatin either alone or mixed with agarose to preliminarily embed collected tissues that are either prefixed or unfixed, followed by conventional fixation, paraffin embedding, freezing, and sectioning. The advantage of the method is that the LM gelatin and its mixture with agarose can be handled at room temperature but quickly hardens at 4°C, which allows embedding, trimming, and arranging of small and fragile tissues in a desired orientation and are compatible with traditional stainings. Thus, this method can have various laboratory applications and can be modified according to the needs of each laboratory.
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Affiliation(s)
- Kaori Ushida
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Technical Center, Nagoya University, Nagoya, Japan
| | - Naoya Asai
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kozo Uchiyama
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Technical Center, Nagoya University, Nagoya, Japan
| | - Atsushi Enomoto
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masahide Takahashi
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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5
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Crawford BM, Shammas RL, Fales AM, Brown DA, Hollenbeck ST, Vo-Dinh T, Devi GR. Photothermal ablation of inflammatory breast cancer tumor emboli using plasmonic gold nanostars. Int J Nanomedicine 2017; 12:6259-6272. [PMID: 28894365 PMCID: PMC5584896 DOI: 10.2147/ijn.s141164] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Inflammatory breast cancer (IBC) is rare, but it is the most aggressive subtype of breast cancer. IBC has a unique presentation of diffuse tumor cell clusters called tumor emboli in the dermis of the chest wall that block lymph vessels causing a painful, erythematous, and edematous breast. Lack of effective therapeutic treatments has caused mortality rates of this cancer to reach 20%–30% in case of women with stage III–IV disease. Plasmonic nanoparticles, via photothermal ablation, are emerging as lead candidates in next-generation cancer treatment for site-specific cell death. Plasmonic gold nanostars (GNS) have an extremely large two-photon luminescence cross-section that allows real-time imaging through multiphoton microscopy, as well as superior photothermal conversion efficiency with highly concentrated heating due to its tip-enhanced plasmonic effect. To effectively study the use of GNS as a clinically plausible treatment of IBC, accurate three-dimensional (3D) preclinical models are needed. Here, we demonstrate a unique in vitro preclinical model that mimics the tumor emboli structures assumed by IBC in vivo using IBC cell lines SUM149 and SUM190. Furthermore, we demonstrate that GNS are endocytosed into multiple cancer cell lines irrespective of receptor status or drug resistance and that these nanoparticles penetrate the tumor embolic core in 3D culture, allowing effective photothermal ablation of the IBC tumor emboli. These results not only provide an avenue for optimizing the diagnostic and therapeutic application of GNS in the treatment of IBC but also support the continuous development of 3D in vitro models for investigating the efficacy of photothermal therapy as well as to further evaluate photothermal therapy in an IBC in vivo model.
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Affiliation(s)
- Bridget M Crawford
- Fitzpatrick Institute for Photonics, Duke University.,Department of Biomedical Engineering, Duke University
| | | | - Andrew M Fales
- Fitzpatrick Institute for Photonics, Duke University.,Department of Biomedical Engineering, Duke University
| | - David A Brown
- Department of Surgery, Division of Plastic, Maxillofacial, and Oral Surgery, Duke University Medical Center
| | - Scott T Hollenbeck
- Department of Surgery, Division of Plastic, Maxillofacial, and Oral Surgery, Duke University Medical Center
| | - Tuan Vo-Dinh
- Fitzpatrick Institute for Photonics, Duke University.,Department of Biomedical Engineering, Duke University.,Department of Chemistry, Duke University
| | - Gayathri R Devi
- Department of Surgery, Division of Surgical Sciences.,Duke Cancer Institute, Women's Cancer Program, Duke University School of Medicine, Durham, NC, USA
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6
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Wang Y, Phillips CN, Herrera GS, Sims CE, Yeh JJ, Allbritton NL. Array of Biodegradable Microraftsfor Isolation and Implantation of Living, Adherent Cells. RSC Adv 2013; 3:9264-9272. [PMID: 23930219 PMCID: PMC3733277 DOI: 10.1039/c3ra41764f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A new strategy for efficient sorting and implantation of viable adherent cells into animals is described. An array of biodegradable micro-structures (microrafts) was fabricated using a polydimethylsiloxane substrate for micromolding poly(lactic-co-glycolic acid) (PLGA). Screening various forms of PLGA determined that the suitability of PLGA for microraft manufacture, biocompatibility and in vitro degradation was dependent on molecular weight and lactic/glycolic ratio. Cells plated on the array selectively attached to the microrafts and could be identified by their fluorescence, morphology or other criteria. The cells were efficiently dislodged and collected from the array using a microneedle device. The platform was used to isolate specific cells from a mixed population establishing the ability to sort target cells for direct implantation. As a proof of concept, fluorescently conjugated microrafts carrying tumor cells stably expressing luciferase were isolated from an array and implanted subcutaneously into mice. In vivo bio-luminescence imaging confirmed the growth of a tumor in the recipient animals. Imaging of tissue sections from the tumors demonstrated in vivo degradation of the implanted microrafts. The process is a new strategy for isolating and delivering a small number of adherent cells for animal implantation with potential applications in tissue repair, tumor induction, in vivo differentiation of stem cells and other biomedical research.
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Affiliation(s)
- Yuli Wang
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599
| | - Colleen N. Phillips
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599
| | - Gabriela S. Herrera
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
| | - Christopher E. Sims
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599
| | - Jen Jen Yeh
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Departments of Surgery and Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Nancy L. Allbritton
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599 and North Carolina State University, Raleigh, NC 27695
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7
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Hruschka V, Meinl A, Saeed A, Cheikh Al Ghanami R, Redl H, Shakesheff K, Wolbank S. Gelatin embedding for the preparation of thermoreversible or delicate scaffolds for histological analysis. Biomed Mater 2013; 8:041001. [PMID: 23735592 DOI: 10.1088/1748-6041/8/4/041001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Thermoreversible hydrogels for tissue engineering (TE) purposes have gained increased attention in recent years as they can be combined with cells and drugs and directly injected into the body. Following the fate of transplanted cells in situ is essential in characterizing their distribution and survival, as well as the expression of specific markers or cell-matrix interactions. Existing histological embedding methods, such as paraffin wax embedding, can mechanically damage some biomaterials during processing. In this study, we describe a broadly applicable preparation protocol that allows the handling of delicate, thermoreversible scaffolds for histological sectioning. The gelatin solution permits the embedding of samples at 37 °C, which suits the solid phase of most TE scaffolds. A thermoreversible scaffold of polycaprolactone microparticles, combined with poly(polyethylene glycol methacrylate ethyl ether) and containing human adipose-derived stem cells, was prepared for histology by an initial gelatin embedding step in addition to the standard cryosectioning and paraffin processing protocols. Sections were evaluated by hematoxylin eosin staining and immunostaining for human vimentin. The gelatin embedding retained the scaffold particles and permitted the complete transfer of the construct. After rapid cooling, the solid gelatin blocks could be cryosectioned and paraffin infiltrated. In contrast to direct cryosectioning or paraffin infiltration, the extended protocol preserved the scaffold structure as well as the relevant cell epitopes, which subsequently allowed for immunostaining of human cells within the material. The gelatin embedding method proposed is a generalizable alternative to standard preparations for histological examination of a variety of delicate samples.
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Affiliation(s)
- Veronika Hruschka
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology/AUVA Research Centre, Vienna, Austria.
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8
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Ng KW, Wanivenhaus F, Chen T, Hsu HC, Allon AA, Abrams VD, Torzilli PA, Warren RF, Maher SA. A novel macroporous polyvinyl alcohol scaffold promotes chondrocyte migration and interface formation in an in vitro cartilage defect model. Tissue Eng Part A 2012; 18:1273-81. [PMID: 22435602 DOI: 10.1089/ten.tea.2011.0276] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Scaffold-cartilage integration is critical for the clinical success of a scaffold used for the repair of a focal cartilage defect. In this study, a macroporous polyvinyl alcohol (PVA) scaffold was found to facilitate chondrocyte infiltration and interfacial matrix formation in a juvenile bovine in vitro cartilage defect model. These results were found to depend on the press-fit between the scaffold and the cartilage, pretreatment of the cartilage with collagenase prior to scaffold insertion, and chondrocyte preseeding of the scaffold. Infiltrated and preseeded chondrocytes in the scaffold survived for 6 weeks in culture and resulted in sufficient matrix at the interface to significantly increase the interface shear strength 30-fold that compared favorably with the interface shear strength of cartilage-cartilage constructs. The ability of this macroporous PVA scaffold to form a stable interface with articular cartilage demonstrates the potential use of this scaffold design for focal cartilage defect repair.
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Affiliation(s)
- Kenneth W Ng
- Hospital for Special Surgery, New York, New York, USA
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9
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Kuzin I, Sun H, Moshkani S, Feng C, Mantalaris A, Wu JHD, Bottaro A. Long-term immunologically competent human peripheral lymphoid tissue cultures in a 3D bioreactor. Biotechnol Bioeng 2011; 108:1430-40. [PMID: 21309085 DOI: 10.1002/bit.23055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 12/23/2010] [Accepted: 01/03/2011] [Indexed: 01/18/2023]
Abstract
Peripheral lymphoid organs (PLOs), the primary sites of development of adaptive immune responses, display a complex structural organization reflecting separation of cellular subsets (e.g., T and B lymphocytes) and functional compartments which is critical for immune function. The generation of in vitro culture systems capable of recapitulating salient features of PLOs for experimental, biotechnological, and clinical applications would be highly desirable, but has been hampered so far by the complexity of these systems. We have previously developed a three-dimensional bioreactor system for long-term, functional culture of human bone marrow cells on macroporous microspheres in a packed-bed bioreactor with frequent medium change. Here we adapt the same system for culture of human primary cells from PLOs (tonsil) in the absence of specific exogenous growth factors or activators. Cells in this system displayed higher viability over several weeks, and maintain population diversity and cell surface markers largely comparable to primary cells. Light microscopy showed cells organizing in large diverse clusters within the scaffold pores and presence of B cell-enriched areas. Strikingly, these cultures generated a significant number of antibody-producing B cells when challenged with a panel of diverse antigens, as expected from a lymphoid tissue. Thus the three-dimensional tonsil bioreactor culture system may serve as a useful model of PLOs by recapitulating their structural organization and function ex vivo.
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Affiliation(s)
- Igor Kuzin
- Department of Medicine, University of Rochester School of Medicine and Dentistry, URMC 695, 601 Elmwood Ave., Rochester, New York 14642, USA
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10
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Foroni L, Dirani G, Gualandi C, Focarete ML, Pasquinelli G. Paraffin Embedding Allows Effective Analysis of Proliferation, Survival, and Immunophenotyping of Cells Cultured on Poly(l-Lactic Acid) Electrospun Nanofiber Scaffolds. Tissue Eng Part C Methods 2010; 16:751-60. [DOI: 10.1089/ten.tec.2009.0316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Laura Foroni
- Department of Specialistic Surgical Anaesthesiological Sciences, University of Bologna, Bologna, Italy
| | - Giorgio Dirani
- Clinical Pathology Division, Department of Radiological and Histocytopathological Sciences, University of Bologna, Bologna, Italy
| | - Chiara Gualandi
- Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, UdR Bologna), University of Bologna, Bologna, Italy
| | - Maria Letizia Focarete
- Department of Chemistry “G. Ciamician” and National Consortium of Materials Science and Technology (INSTM, UdR Bologna), University of Bologna, Bologna, Italy
| | - Gianandrea Pasquinelli
- Clinical Pathology Division, Department of Radiological and Histocytopathological Sciences, University of Bologna, Bologna, Italy
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11
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Pham EA, Ho WJ, Kamei DT, Wu BM. Modification of the diphenylamine assay for cell quantification in three-dimensional biodegradable polymeric scaffolds. J Biomed Mater Res B Appl Biomater 2010; 92:499-507. [PMID: 19957351 DOI: 10.1002/jbm.b.31543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
As three-dimensional (3D) cell culture systems gain popularity in biomedical research, reliable assays for cell proliferation within 3D matrices become more important. Although many cell quantification techniques have been established for cells cultured on nondegradable plastic culture dishes and cells suspended in media, it is becoming increasingly clear that cell quantification after prolonged culture in 3D polymeric scaffolds imposes unique challenges because the added presence of polymeric materials may contribute to background signal via various mechanisms including autofluorescence, diffusion gradients, and sequestering effects. Thus, additional steps are required to ensure complete isolation of cells from the 3D scaffold. The diphenylamine assay isolates cellular DNA, degrades the polymeric matrix materials, and reacts with the DNA to yield a colorimetric response. Thus, we report here a practical modification of the diphenylamine assay and show that the assay quantifies cells in 3D polyester scaffolds reliably and reproducibly as long as the necessary amount of the acidic working reagent is present. Our study also demonstrates that the sensitivity of the assay can be optimized by controlling the dimensions of the sampling volume. Overall, the DPA assay offers an attractive solution for challenges associated with 3D cell quantification.
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Affiliation(s)
- Edward A Pham
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA
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12
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Farng E, Urdaneta AR, Barba D, Esmende S, McAllister DR. The effects of GDF-5 and uniaxial strain on mesenchymal stem cells in 3-D culture. Clin Orthop Relat Res 2008; 466:1930-7. [PMID: 18535869 PMCID: PMC2584265 DOI: 10.1007/s11999-008-0300-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 04/29/2008] [Indexed: 01/31/2023]
Abstract
Recent endeavors in tissue engineering have attempted to identify the optimal parameters to create an artificial ligament. Both mechanical and biochemical stimulation have been used by others to independently modulate growth and differentiation, although few studies have explored their interactions. We applied previously described fabrication techniques to create a highly porous (90%-95% porosity, 212-300 microm), 3-D, bioabsorbable polymer scaffold (polycaprolactone). Scaffolds were coated with bovine collagen, and growth and differentiation factor 5 (GDF-5) was added to half of the scaffolds. Scaffolds were seeded with mesenchymal stem cells and cultured in a custom bioreactor under static or cyclic strain (10% strain, 0.33 Hz) conditions. After 48 hours, both mechanical stimulation and GDF-5 increased mRNA production of collagen I, II, and scleraxis compared to control; tenascin C production was not increased. Combining stimuli did not change gene expression; however, cellular metabolism was 1.7 times higher in scaffolds treated with both stimuli. We successfully grew a line of mesenchymal stem cells in 3-D culture, and our initial data indicate mechanical stimulation and GDF-5 influenced cellular activity and mRNA production; we did not, however, observe additive synergism with the mechanical and biological stimuli.
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Affiliation(s)
- Eugene Farng
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California Medical Center, 10833 Le Conte Avenue, Room 16-155 CHS, Los Angeles, CA 90095, USA.
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13
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Nygaard J, Andersen M, Howard K, Foss M, Bünger C, Kjems J, Besenbacher F. Investigation of particle-functionalized tissue engineering scaffolds using X-ray tomographic microscopy. Biotechnol Bioeng 2008; 100:820-9. [DOI: 10.1002/bit.21796] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Abstract
Cell growth is critical to the regeneration of most tissues. Current methods for analyzing cell growth in scaffolds used for tissue engineering are reviewed in the context of their limitations. A mathematical model for analyzing cell growth in scaffolds is presented to highlight the key parameters that govern cell growth. To overcome the diffusion barrier that limits the formation of thicker tissues, strategies to promote better nutrient delivery are discussed.
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Affiliation(s)
- James CY Dunn
- Mail Code 709818, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
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15
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Petrigliano FA, English CS, Barba D, Esmende S, Wu BM, McAllister DR. The effects of local bFGF release and uniaxial strain on cellular adaptation and gene expression in a 3D environment: implications for ligament tissue engineering. ACTA ACUST UNITED AC 2008; 13:2721-31. [PMID: 17727336 DOI: 10.1089/ten.2006.0434] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The objectives of this investigation were (1) to characterize the growth factor release profile of a basic fibroblast growth factor (bFGF)-coated three-dimensional (3D) polymer scaffold under static and cyclically strained conditions, and (2) to delineate the individual and collective contributions of locally released bFGF and mechanical strain on cellular morphology and gene expression in this 3D system. Scaffolds were treated with I(125)-bFGF and subjected to mechanical strain or maintained in a static environment and the media sampled for factor release over a period of 6 days. Over the first 10 hours, a burst release of 25% of the incorporated growth factor into the surrounding media was noted. At 24 hours, approximately 40% of the bFGF was released into the media, after which steady state was achieved and minimal subsequent release was noted. Mechanical stimulation had no effect on growth factor release from the scaffold in this system. To test the concerted effects of bFGF and mechanical stimulation on bone marrow stromal cells (BMSCs), scaffolds were loaded with 0, 100, or 500 ng of bFGF, seeded with cells, and subjected to mechanical strain or maintained in a static environment. Scaffolds were harvested at 1, 7, and 21 days for RT-PCR and histomorphometry. All scaffolds subjected to growth factor and/or mechanical stimulation demonstrated cellular adherence and spreading at 21 days. Conversely, in the absence of both bFGF and mechanical stimulation, cells demonstrated minimal cytoplasmic spread. Moreover, at 21 days, cells subjected to both mechanical stimulation and bFGF (500 ng) demonstrated the highest upregulation of stress-resistive (collagen I, III) and stress-responsive proteins (tenascin-C). The effect of growth factor may be dose sensitive, however, as unstrained scaffolds treated with 100 ng of bFGF demonstrated upregulation of gene expression comparable to strained scaffolds treated with lower doses of bFGF (0 or 100 ng). In conclusion, results from this study suggest that the stimulatory effects of bFGF are dose sensitive and appear to be influenced by the addition of mechanical strain. The concurrent application of biochemical and mechanical stimuli may be important in promoting the adaptation of BMSCs and driving the transcription of genes essential for synthesis of a functional ligament replacement tissue.
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Affiliation(s)
- Frank A Petrigliano
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California Medical Center, Los Angeles, California 90095, USA.
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Dunn JCY, Chan WY, Cristini V, Kim JS, Lowengrub J, Singh S, Wu BM. Analysis of Cell Growth in Three-Dimensional Scaffolds. ACTA ACUST UNITED AC 2006; 12:705-16. [PMID: 16674285 DOI: 10.1089/ten.2006.12.705] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The in vitro growth of pre-osteoblasts in multi-layer, three-dimensional scaffolds was determined from experimental measurements and was compared to a mathematical model. Immediately following cell seeding, the initial cell density was uniform throughout the scaffold. After 10 days, the cell density increased from 2.1 x 10(5) cells/cm(3) to 1.3 x 10(7) cells/cm(3) at the fluid-scaffold interface. The increase in cell density was largely confined to the outermost 200 microm from the fluid-scaffold interface. The cell density profile was in good agreement with a mathematical model that simulated the cell growth based on the local oxygen tension. The improved understanding derived from this mathematical model may be useful in the design of three-dimensional scaffolds that can support more uniform growth of cells.
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Affiliation(s)
- James C Y Dunn
- Department of Bioengineering, University of California, Los Angeles, USA.
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Chou YF, Dunn JCY, Wu BM. In vitro response of MC3T3-E1 pre-osteoblasts within three-dimensional apatite-coated PLGA scaffolds. J Biomed Mater Res B Appl Biomater 2006; 75:81-90. [PMID: 16001421 DOI: 10.1002/jbm.b.30261] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Biomimetic apatites have been reported to promote osteogenic activities in numerous in vivo and in vitro models, but the precise mechanism by which the apatite microenvironment promotes such activities is not well understood. Such mechanistic studies require reproducible model systems that are relevant to tissue engineering practices. Although two-dimensional (2D) apatite-coated polystyrene culture dishes provide practicality and reproducibility, they do not simulate the effects of the three-dimensional (3D) microenvironment and degrading polymeric substrates. A simple 3D model system to address these relevant effects, and its utilization in the investigation of apatite-promoted osteoblastic differentiation in vitro is reported in this paper. Apatite coating was achieved by sequentially immersing poly(lactide-co-glycolide) (PLGA) scaffolds into different simulated body fluids (SBF). SEM, EDX, FTIR, TEM electron diffraction confirmed the apatite coating to comprise of calcium-deficient carbonated hydroxyapatite crystals. While both apatite-coated and non-coated PLGA scaffolds supported MC3T3-E1 attachment, spreading, and proliferation, significant differences in osteoblastic differentiation were observed. Relative to non-coated controls, quantitative real-time PCR revealed significant apatite-associated suppression of alkaline phosphatase (ALP), early upregulation of osteopontin (OPN) at 3 days, and upregulation of osteocalcin (OCN) and bone sialoprotein (BSP) at 4 weeks. In summary, apatite-promoted osteoblastic differentiation can be observed in a 3D model system that is relevant to tissue engineering.
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Affiliation(s)
- Yu-Fen Chou
- Department of Bioengineering, 7525 Boelter Hall, University of California, Los Angeles, California 90095, USA
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