1
|
van der Putten C, Sahin G, Grant R, D’Urso M, Giselbrecht S, Bouten CVC, Kurniawan NA. Dimensionality Matters: Exploiting UV-Photopatterned 2D and Two-Photon-Printed 2.5D Contact Guidance Cues to Control Corneal Fibroblast Behavior and Collagen Deposition. Bioengineering (Basel) 2024; 11:402. [PMID: 38671823 PMCID: PMC11048187 DOI: 10.3390/bioengineering11040402] [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: 04/03/2024] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
In the event of disease or injury, restoration of the native organization of cells and extracellular matrix is crucial for regaining tissue functionality. In the cornea, a highly organized collagenous tissue, keratocytes can align along the anisotropy of the physical microenvironment, providing a blueprint for guiding the organization of the collagenous matrix. Inspired by this physiological process, anisotropic contact guidance cues have been employed to steer the alignment of keratocytes as a first step to engineer in vitro cornea-like tissues. Despite promising results, two major hurdles must still be overcome to advance the field. First, there is an enormous design space to be explored in optimizing cellular contact guidance in three dimensions. Second, the role of contact guidance cues in directing the long-term deposition and organization of extracellular matrix proteins remains unknown. To address these challenges, here we combined two microengineering strategies-UV-based protein patterning (2D) and two-photon polymerization of topographies (2.5D)-to create a library of anisotropic contact guidance cues with systematically varying height (H, 0 µm ≤ H ≤ 20 µm) and width (W, 5 µm ≤ W ≤ 100 µm). With this unique approach, we found that, in the short term (24 h), the orientation and morphology of primary human fibroblastic keratocytes were critically determined not only by the pattern width, but also by the height of the contact guidance cues. Upon extended 7-day cultures, keratocytes were shown to produce a dense, fibrous collagen network along the direction of the contact guidance cues. Moreover, increasing the heights also increased the aligned fraction of deposited collagen and the contact guidance response of cells, all whilst the cells maintained the fibroblastic keratocyte phenotype. Our study thus reveals the importance of dimensionality of the physical microenvironment in steering both cellular organization and the formation of aligned, collagenous tissues.
Collapse
Affiliation(s)
- Cas van der Putten
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Gozde Sahin
- MERLN Institute for Technology-Inspired Regenerative Medicine, Department of Cell Biology-Inspired Tissue Engineering cBITE, 6229 ER Maastricht, The Netherlands
| | - Rhiannon Grant
- MERLN Institute for Technology-Inspired Regenerative Medicine, Department of Cell Biology-Inspired Tissue Engineering cBITE, 6229 ER Maastricht, The Netherlands
| | - Mirko D’Urso
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Stefan Giselbrecht
- MERLN Institute for Technology-Inspired Regenerative Medicine, Department of Cell Biology-Inspired Tissue Engineering cBITE, 6229 ER Maastricht, The Netherlands
| | - Carlijn V. C. Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Nicholas A. Kurniawan
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| |
Collapse
|
2
|
Schamberger B, Ehrig S, Dechat T, Spitzer S, Bidan CM, Fratzl P, Dunlop JWC, Roschger A. Twisted-plywood-like tissue formation in vitro. Does curvature do the twist? PNAS Nexus 2024; 3:pgae121. [PMID: 38590971 PMCID: PMC10999733 DOI: 10.1093/pnasnexus/pgae121] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 02/23/2024] [Indexed: 04/10/2024]
Abstract
Little is known about the contribution of 3D surface geometry to the development of multilayered tissues containing fibrous extracellular matrix components, such as those found in bone. In this study, we elucidate the role of curvature in the formation of chiral, twisted-plywood-like structures. Tissues consisting of murine preosteoblast cells (MC3T3-E1) were grown on 3D scaffolds with constant-mean curvature and negative Gaussian curvature for up to 32 days. Using 3D fluorescence microscopy, the influence of surface curvature on actin stress-fiber alignment and chirality was investigated. To gain mechanistic insights, we did experiments with MC3T3-E1 cells deficient in nuclear A-type lamins or treated with drugs targeting cytoskeleton proteins. We find that wild-type cells form a thick tissue with fibers predominantly aligned along directions of negative curvature, but exhibiting a twist in orientation with respect to older tissues. Fiber orientation is conserved below the tissue surface, thus creating a twisted-plywood-like material. We further show that this alignment pattern strongly depends on the structural components of the cells (A-type lamins, actin, and myosin), showing a role of mechanosensing on tissue organization. Our data indicate the importance of substrate curvature in the formation of 3D tissues and provide insights into the emergence of chirality.
Collapse
Affiliation(s)
- Barbara Schamberger
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
| | - Sebastian Ehrig
- Laboratory of Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Hannoversche Str. 28, 10115 Berlin, Germany
| | - Thomas Dechat
- Ludwig Boltzmann Institute of Osteology of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria
| | - Silvia Spitzer
- Ludwig Boltzmann Institute of Osteology of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria
| | - Cécile M Bidan
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Peter Fratzl
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - John W C Dunlop
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
| | - Andreas Roschger
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
| |
Collapse
|
3
|
Giacomini F, Baião Barata D, Suk Rho H, Tahmasebi Birgani Z, van Blitterswijk C, Giselbrecht S, Truckenmüller R, Habibović P. Microfluidically Aligned Collagen to Maintain the Phenotype of Tenocytes In Vitro. Adv Healthc Mater 2024; 13:e2303672. [PMID: 37902084 DOI: 10.1002/adhm.202303672] [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] [Received: 10/24/2023] [Indexed: 10/31/2023]
Abstract
Tendon is a highly organized tissue that transmits forces between muscle and bone. The architecture of the extracellular matrix of tendon, predominantly from collagen type I, is important for maintaining tenocyte phenotype and function. Therefore, in repair and regeneration of damaged and diseased tendon tissue, it is crucial to restore the aligned arrangement of the collagen type I fibers of the original matrix. To this end, a novel, user-friendly microfluidic piggyback platform is developed allowing the controlled patterned formation and alignment of collagen fibers simply on the bottom of culture dishes. Rat tenocytes cultured on the micropatterns of aligned fibrous collagen exhibit a more elongated morphology. The cells also show an increased expression of tenogenic markers at the gene and protein level compared to tenocytes cultured on tissue culture plastic or non-fibrillar collagen coatings. Moreover, using imprinted polystyrene replicas of aligned collagen fibers, this work shows that the fibrillar structure of collagen per se affects the tenocyte morphology, whereas the biochemical nature of collagen plays a prominent role in the expression of tenogenic markers. Beyond the controlled provision of aligned collagen, the microfluidic platform can aid in developing more physiologically relevant in vitro models of tendon and its regeneration.
Collapse
Affiliation(s)
- Francesca Giacomini
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - David Baião Barata
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, Lisbon, 1649-028, Portugal
| | - Hoon Suk Rho
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - Zeinab Tahmasebi Birgani
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - Clemens van Blitterswijk
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - Stefan Giselbrecht
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - Roman Truckenmüller
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| | - Pamela Habibović
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, Maastricht, 6229 ER, The Netherlands
| |
Collapse
|
4
|
Sapudom J, Karaman S, Quartey BC, Mohamed WKE, Mahtani N, Garcia-Sabaté A, Teo J. Collagen Fibril Orientation Instructs Fibroblast Differentiation Via Cell Contractility. Adv Sci (Weinh) 2023:e2301353. [PMID: 37249413 PMCID: PMC10401101 DOI: 10.1002/advs.202301353] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/03/2023] [Indexed: 05/31/2023]
Abstract
Collagen alignment is one of the key microarchitectural signatures of many pathological conditions, including scarring and fibrosis. Investigating how collagen alignment modulates cellular functions will pave the way for understanding tissue scarring and regeneration and new therapeutic strategies. However, current approaches for the fabrication of three-dimensional (3D) aligned collagen matrices are low-throughput and require special devices. To overcome these limitations, a simple approach to reconstitute homogeneous 3D collagen matrices with adjustable degree of fibril alignment using 3D printed inclined surfaces is developed. By characterizing the mechanical properties of reconstituted matrices, it is found that the elastic modulus of collagen matrices is enhanced with an increase in the alignment degree. The reconstituted matrices are used to study fibroblast behavior to reveal the progression of scar formation where a gradual enhancement of collagen alignment can be observed. It is found that matrices with aligned fibrils trigger fibroblast differentiation into myofibroblasts via cell contractility, while collagen stiffening through a crosslinker does not. The results suggest the impact of collagen fibril organization on the regulation of fibroblast differentiation. Overall, this approach to reconstitute 3D collagen matrices with fibril alignment opens opportunities for biomimetic pathological-relevant tissue in vitro, which can be applied for other biomedical research.
Collapse
Affiliation(s)
- Jiranuwat Sapudom
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Shaza Karaman
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Brian Chesney Quartey
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Walaa Kamal Eldin Mohamed
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Nick Mahtani
- School of Engineering, Ecole Polytechnique Federale de Lausanne, Lausanne, 1015, Switzerland
| | - Anna Garcia-Sabaté
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Jeremy Teo
- Laboratory for Immuno Bioengineering Research and Applications, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
- Department of Mechanical and Biomedical Engineering, Tandon School of Engineering, New York University, New York, 11201, USA
| |
Collapse
|
5
|
Abstract
OBJECTIVE There has been a debate as to the alignment of the collagen fibers. Using a hand lens, Sir William Hunter demonstrated that the collagen fibers ran perpendicular and later aspects were supported by Benninghoff. Despite these 2 historical studies, modern technology has conflicting data on the collagen alignment. DESIGN Ten mature New Zealand rabbits were used to obtain 40 condyle specimens. The specimens were passed through ascending grades of alcohol, subjected to critical point drying (CPD), and viewed in the scanning electron microscope. Specimens revealed splits from the dehydration process. When observing the fibers exposed within the opening of the splits, parallel fibers were observed to run in a radial direction, normal to the surface of the articular cartilage, radiating from the deep zone and arcading as they approach the surface layer. After these observations, the same samples were mechanically fractured and damaged by scalpel. RESULTS The splits in the articular surface created deep fissures, exposing parallel bundles of collagen fibers, radiating from the deep zone and arcading as they approach the surface layer. On higher magnification, individual fibers were observed to run parallel to one another, traversing radially toward the surface of the articular cartilage and arcading. Mechanical fracturing and scalpel damage induced on the same specimens with the splits showed randomly oriented fibers. CONCLUSION Collagen fiber orientation corroborates aspects of Hunter's findings and compliments Benninghoff. Investigators must be aware of the limits of their processing and imaging techniques in order to interpret collagen fiber orientation in cartilage.
Collapse
Affiliation(s)
- Roy D. Bloebaum
- Department of Orthopaedics, University
of Utah School of Medicine, Salt Lake City, UT, USA
| | - Andrew S. Wilson
- Department of Anatomy, School of Human
Sciences, The University of Western Australia, Perth, Western Australia,
Australia
| | - William N. Martin
- Department of Orthopaedics, University
of Utah School of Medicine, Salt Lake City, UT, USA,William N. Martin, 9862 South Granite Slope
Drive, Sandy, UT 84092, USA. Email
| |
Collapse
|
6
|
Smith MV, Castile RM, Brophy RH, Dewan A, Bernholt D, Lake SP. Mechanical Properties and Microstructural Collagen Alignment of the Ulnar Collateral Ligament During Dynamic Loading. Am J Sports Med 2019; 47:151-157. [PMID: 30495972 DOI: 10.1177/0363546518812416] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The ulnar collateral ligament (UCL) microstructural organization and collagen fiber realignment in response to load are unknown. PURPOSE/HYPOTHESIS The purpose was to describe the real-time microstructural collagen changes in the anterior bundle (AB) and posterior bundle (PB) of the UCL with tensile load. It was hypothesized that the UCL AB is stronger and stiffer with more highly aligned collagen during loading when compared with the UCL PB. STUDY DESIGN Descriptive laboratory study. METHODS The AB and PB from 34 fresh cadaveric specimens were longitudinally sectioned to allow uniform light passage for quantitative polarized light imaging. Specimens were secured to a tensile test machine and underwent cyclic preconditioning, a ramp-and-hold stress-relaxation test, and a quasi-static ramp to failure. A division-of-focal-plane polarization camera captured real-time pixelwise microstructural data of each sample during stress-relaxation and at the zero, transition, and linear points of the stress-strain curve. The SD of the angle of polarization determined the deviation of the average direction of collagen fibers in the tissue, while the average degree of linear polarization evaluated the strength of collagen alignment in those directions. Since the data were nonnormally distributed, the median ± interquartile range are presented. RESULTS The AB has larger elastic moduli than the PB ( P < .0001) in the toe region (median, 2.73 MPa [interquartile range, 1.1-5.6 MPa] vs 0.65 MPa [0.44-1.5 MPa]) and the linear region (13.77 MPa [4.8-40.7 MPa] vs 1.96 MPa [0.58-9.3 MPa]). The AB demonstrated larger stress values, stronger collagen alignment, and more uniform collagen organization during stress-relaxation. PB collagen fibers were more disorganized than the AB during the zero ( P = .046), transitional ( P = .011), and linear ( P = .007) regions of the stress-strain curve. Both UCL bundles exhibited very small changes in collagen alignment (SD of the angle of polarization) with load. CONCLUSION The AB of the UCL is stiffer and stronger, with more strongly aligned and more uniformly oriented collagen fibers, than the PB. The small changes in collagen alignment indicate that the UCL response to load is due more to its static collagen organization than to dynamic changes in collagen alignment. CLINICAL RELEVANCE The UCL collagen organization may explain its susceptibility to injury with repetitive valgus loads.
Collapse
Affiliation(s)
- Matthew V Smith
- Department of Orthopaedic Surgery, Washington University, St Louis, Missouri, USA
| | - Ryan M Castile
- Department of Mechanical Engineering and Materials Science, Washington University, St Louis, Missouri, USA
| | - Robert H Brophy
- Department of Orthopaedic Surgery, Washington University, St Louis, Missouri, USA
| | - Ashvin Dewan
- Methodist Orthopedic Specialists of Texas, Sugar Land, Texas, USA
| | - David Bernholt
- Department of Orthopaedic Surgery, Washington University, St Louis, Missouri, USA
| | - Spencer P Lake
- Department of Orthopaedic Surgery, Washington University, St Louis, Missouri, USA.,Department of Mechanical Engineering and Materials Science, Washington University, St Louis, Missouri, USA
| |
Collapse
|
7
|
McCoy MG, Wei JM, Choi S, Goerger JP, Zipfel W, Fischbach C. Collagen Fiber Orientation Regulates 3D Vascular Network Formation and Alignment. ACS Biomater Sci Eng 2018; 4:2967-2976. [PMID: 33435017 DOI: 10.1021/acsbiomaterials.8b00384] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Alignment of collagen type I fibers is a hallmark of both physiological and pathological tissue remodeling. However, the effects of collagen fiber orientation on endothelial cell behavior and vascular network formation are poorly understood because of a lack of model systems that allow studying these potential functional connections. By casting collagen type I into prestrained (0, 10, 25, 50% strain), poly(dimethylsiloxane) (PDMS)-based microwells and releasing the mold strain following polymerization, we have created collagen gels with varying fiber alignment as confirmed by structural analysis. Endothelial cells embedded within the different gels responded to increased collagen fiber orientation by assembling into 3D vascular networks that consisted of thicker, more aligned branches and featured elevated collagen IV deposition and lumen formation relative to control conditions. These substrate-dependent changes in microvascular network formation were associated with altered cell division and migration patterns and related to enhanced mechanosignaling. Our studies indicate that collagen fiber alignment can directly regulate vascular network formation and that culture models with aligned collagen may be used to investigate the underlying mechanisms ultimately advancing our understanding of tissue development, homeostasis, and disease.
Collapse
Affiliation(s)
- Michael G McCoy
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Jane M Wei
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States.,Biological Sciences, Cornell University, Ithaca, New York 14853, United States
| | - Siyoung Choi
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Julian Palacios Goerger
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Warren Zipfel
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Claudia Fischbach
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| |
Collapse
|
8
|
Abstract
Cell migration is strongly influenced by the organization of the surrounding 3-D extracellular matrix. In particular, within fibrous solid tumors, carcinoma cell invasion may be directed by patterns of aligned collagen in the extra-epithelial space. Thus, studying the interactions of heterogeneous populations of cancer cells that include the stem/progenitor-like cancer stem cell subpopulation and aligned collagen networks is critical to our understanding of carcinoma dissemination. Here, we describe a robust method to generate aligned collagen matrices in vitro that mimic in vivo fiber organization. Subsequently, a protocol is presented for seeding aligned matrices with distinct carcinoma cell subpopulations and performing live cell imaging and quantitative analysis of cell migration. Together, the engineered constructs and the imaging techniques laid out here provide a platform to study cancer stem cell migration in 3-D anisotropic collagen with real-time visualization of cellular interactions with the fibrous matrix. © 2018 by John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- Arja Ray
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.,University of Minnesota Physical Sciences in Oncology Center, Minneapolis, Minnesota
| | - Rachel K Morford
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.,University of Minnesota Physical Sciences in Oncology Center, Minneapolis, Minnesota
| | - Paolo P Provenzano
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.,University of Minnesota Physical Sciences in Oncology Center, Minneapolis, Minnesota.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.,Stem Cell Institute, University of Minnesota, Minneapolis, Minnesota.,Institute for Engineering in Medicine, University of Minnesota, Minneapolis, Minnesota
| |
Collapse
|