1
|
Zhang S, Grifno G, Passaro R, Regan K, Zheng S, Hadzipasic M, Banerji R, O'Connor L, Chu V, Kim SY, Yang J, Shi L, Karrobi K, Roblyer D, Grinstaff MW, Nia HT. Intravital measurements of solid stresses in tumours reveal length-scale and microenvironmentally dependent force transmission. Nat Biomed Eng 2023; 7:1473-1492. [PMID: 37640900 PMCID: PMC10836235 DOI: 10.1038/s41551-023-01080-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/19/2023] [Indexed: 08/31/2023]
Abstract
In cancer, solid stresses impede the delivery of therapeutics to tumours and the trafficking and tumour infiltration of immune cells. Understanding such consequences and the origin of solid stresses requires their probing in vivo at the cellular scale. Here we report a method for performing volumetric and longitudinal measurements of solid stresses in vivo, and findings from its applicability to tumours. We used multimodal intravital microscopy of fluorescently labelled polyacrylamide beads injected in breast tumours in mice as well as mathematical modelling to compare solid stresses at the single-cell and tissue scales, in primary and metastatic tumours, in vitro and in mice, and in live mice and post-mortem tissue. We found that solid-stress transmission is scale dependent, with tumour cells experiencing lower stresses than their embedding tissue, and that tumour cells in lung metastases experience substantially higher solid stresses than those in the primary tumours. The dependence of solid stresses on length scale and the microenvironment may inform the development of therapeutics that sensitize cancer cells to such mechanical forces.
Collapse
Affiliation(s)
- Sue Zhang
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Gabrielle Grifno
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Rachel Passaro
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Kathryn Regan
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Siyi Zheng
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Muhamed Hadzipasic
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, USA
| | - Rohin Banerji
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Logan O'Connor
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Vinson Chu
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sung Yeon Kim
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Jiarui Yang
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Linzheng Shi
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Kavon Karrobi
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Darren Roblyer
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Mark W Grinstaff
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Department of Chemistry, Boston University, Boston, MA, USA
| | - Hadi T Nia
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
| |
Collapse
|
2
|
Dubay R, Darling EM, Fiering J. Microparticles with tunable, cell-like properties for quantitative acoustic mechanophenotyping. MICROSYSTEMS & NANOENGINEERING 2023; 9:90. [PMID: 37448969 PMCID: PMC10336031 DOI: 10.1038/s41378-023-00556-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/21/2023] [Accepted: 05/08/2023] [Indexed: 07/18/2023]
Abstract
Mechanical properties of biological cells have been shown to correlate with their biomolecular state and function, and therefore methods to measure these properties at scale are of interest. Emerging microfluidic technologies can measure the mechanical properties of cells at rates over 20,000 cells/s, which is more than four orders of magnitude faster than conventional instrumentation. However, precise and repeatable means to calibrate and test these new tools remain lacking, since cells themselves are by nature variable. Commonly, microfluidic tools use rigid polymer microspheres for calibration because they are widely available in cell-similar sizes, but conventional microspheres do not fully capture the physiological range of other mechanical properties that are equally important to device function (e.g., elastic modulus and density). Here, we present for the first time development of monodisperse polyacrylamide microparticles with both tunable elasticity and tunable density. Using these size, elasticity, and density tunable particles, we characterized a custom acoustic microfluidic device that makes single-cell measurements of mechanical properties. We then applied the approach to measure the distribution of the acoustic properties within samples of human leukocytes and showed that the system successfully discriminates lymphocytes from other leukocytes. This initial demonstration shows how the tunable microparticles with properties within the physiologically relevant range can be used in conjunction with microfluidic devices for efficient high-throughput measurements of mechanical properties at single-cell resolution.
Collapse
Affiliation(s)
- Ryan Dubay
- Center for Biomedical Engineering, Brown University, Providence, RI 02912 USA
- Biological Microsystems, Draper, Cambridge, MA 02139 USA
| | - Eric M. Darling
- Center for Biomedical Engineering, Brown University, Providence, RI 02912 USA
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI 02912 USA
- School of Engineering, Brown University, Providence, RI 02912 USA
- Department of Orthopaedics, Brown University, Providence, RI 02912 USA
| | - Jason Fiering
- Biological Microsystems, Draper, Cambridge, MA 02139 USA
| |
Collapse
|
3
|
Guttenplan APM, Tahmasebi Birgani Z, Giselbrecht S, Truckenmüller RK, Habibović P. Chips for Biomaterials and Biomaterials for Chips: Recent Advances at the Interface between Microfabrication and Biomaterials Research. Adv Healthc Mater 2021; 10:e2100371. [PMID: 34033239 DOI: 10.1002/adhm.202100371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/08/2021] [Indexed: 12/24/2022]
Abstract
In recent years, the use of microfabrication techniques has allowed biomaterials studies which were originally carried out at larger length scales to be miniaturized as so-called "on-chip" experiments. These miniaturized experiments have a range of advantages which have led to an increase in their popularity. A range of biomaterial shapes and compositions are synthesized or manufactured on chip. Moreover, chips are developed to investigate specific aspects of interactions between biomaterials and biological systems. Finally, biomaterials are used in microfabricated devices to replicate the physiological microenvironment in studies using so-called "organ-on-chip," "tissue-on-chip" or "disease-on-chip" models, which can reduce the use of animal models with their inherent high cost and ethical issues, and due to the possible use of human cells can increase the translation of research from lab to clinic. This review gives an overview of recent developments at the interface between microfabrication and biomaterials science, and indicates potential future directions that the field may take. In particular, a trend toward increased scale and automation is apparent, allowing both industrial production of micron-scale biomaterials and high-throughput screening of the interaction of diverse materials libraries with cells and bioengineered tissues and organs.
Collapse
Affiliation(s)
- Alexander P. M. Guttenplan
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University Universiteitssingel 40 Maastricht 6229ER The Netherlands
| | - Zeinab Tahmasebi Birgani
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University Universiteitssingel 40 Maastricht 6229ER The Netherlands
| | - Stefan Giselbrecht
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University Universiteitssingel 40 Maastricht 6229ER The Netherlands
| | - Roman K. Truckenmüller
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University Universiteitssingel 40 Maastricht 6229ER The Netherlands
| | - Pamela Habibović
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University Universiteitssingel 40 Maastricht 6229ER The Netherlands
| |
Collapse
|
4
|
Gutierrez RA, Fang W, Kesari H, Darling EM. Force sensors for measuring microenvironmental forces during mesenchymal condensation. Biomaterials 2021; 270:120684. [PMID: 33535143 DOI: 10.1016/j.biomaterials.2021.120684] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 12/30/2022]
Abstract
Mechanical forces are an essential element to early tissue formation. However, few techniques exist that can quantify the mechanical microenvironment present within cell-dense neotissues and organoid structures. Here is a versatile approach to measure microscale, cellular forces during mesenchymal condensation using specially tailored, hyper-compliant microparticles (HCMPs). Through monitoring of HCMP deformation over both space and time, measurements of the mechanical forces that cells exert, and have exerted on them, during tissue formation are acquired. The current study uses this technology to track changes in the mechanical microenvironment as mesenchymal stem cells self-assemble into spheroids and condense into cohesive units. An array analysis approach, using a high-content imaging system, shows that cells exert a wide range of tensile and compressive forces during the first few hours of self-assembly, followed by a period of relative equilibrium. Cellular interactions with HCMPs are further examined by applying collagen coating, which allows for increased tensile forces to be exerted compared to non-coated HCMPs. Importantly, the hyper-compliant nature of our force sensors allows for increased precision over less compliant versions of the same particle. This sensitivity resolves small changes in the microenvironment even at the earliest stages of development and morphogenesis. The overall experimental platform provides a versatile means for measuring direct and indirect spatiotemporal forces in cell-dense biological systems.
Collapse
Affiliation(s)
- Robert A Gutierrez
- Center for Biomedical Engineering, Brown University, Providence, RI, 02912, USA
| | - Wenqiang Fang
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - Haneesh Kesari
- School of Engineering, Brown University, Providence, RI, 02912, USA.
| | - Eric M Darling
- Center for Biomedical Engineering, Brown University, Providence, RI, 02912, USA; School of Engineering, Brown University, Providence, RI, 02912, USA; Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, 02912, USA; Department of Orthopaedics, Brown University, Providence, RI, 02912, USA.
| |
Collapse
|
5
|
Dubay R, Fiering J, Darling EM. Effect of elastic modulus on inertial displacement of cell-like particles in microchannels. BIOMICROFLUIDICS 2020; 14:044110. [PMID: 32774585 PMCID: PMC7402708 DOI: 10.1063/5.0017770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/21/2020] [Indexed: 05/07/2023]
Abstract
Label-free microfluidic-based cell sorters leverage innate differences among cells (e.g., size and stiffness), to separate one cell type from another. This sorting step is crucial for many cell-based applications. Polystyrene-based microparticles (MPs) are the current gold standard for calibrating flow-based cell sorters and analyzers; however, the deformation behavior of these rigid materials is drastically different from that of living cells. Given this discrepancy in stiffness, an alternative calibration particle that better reflects cell elasticity is needed for the optimization of new and existing microfluidic devices. Here, we describe the fabrication of cell-like, mechanically tunable MPs and demonstrate their utility in quantifying differences in inertial displacement within a microfluidic constriction device as a function of particle elastic modulus, for the first time. Monodisperse, fluorescent, cell-like microparticles that replicate the size and modulus of living cells were fabricated from polyacrylamide within a microfluidic droplet generator and characterized via optical and atomic force microscopy. Trajectories of our cell-like MPs were mapped within the constriction device to predict where living cells of similar size/modulus would move. Calibration of the device with our MPs showed that inertial displacement depends on both particle size and modulus, with large/soft MPs migrating further toward the channel centerline than small/stiff MPs. The mapped trajectories also indicated that MP modulus contributed proportionally more to particle displacement than size, for the physiologically relevant ranges tested. The large shift in focusing position quantified here emphasizes the need for physiologically relevant, deformable MPs for calibrating and optimizing microfluidic separation platforms.
Collapse
Affiliation(s)
| | - J. Fiering
- Draper, Cambridge, Massachusetts 02139, USA
| | | |
Collapse
|
6
|
Gangotra A, Biviano M, Dagastine RR, Berry JD, Willmott GR. Use of microaspiration to study the mechanical properties of polymer gel microparticles. SOFT MATTER 2019; 15:7286-7294. [PMID: 31498362 DOI: 10.1039/c9sm00862d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The mechanical properties of polyacrylamide (PA) and polydimethylsiloxane (PDMS) microparticle populations have been measured using microaspiration, a recently developed experimental technique. Microaspiration is an augmented version of micropipette aspiration, in which optical microscopy data are obtained as individual soft particles pass through the tip of a micropipette. During microaspiration, the ion current passing through the pipette tip is also measured, and the synchronised optical and current data streams are used to study and quantify mechanical properties. Ion current signatures for the poroelastic PA particles were qualitatively different from those of the viscoelastic PDMS particles. For PA particles the current gradually reduced during each aspiration event, whereas for PDMS particles the current trace resembled a negative top hat function. For PA particles it was found that the maximum change in current during aspiration (ΔIh) increased with particle size. By considering the initial elastic response, a mean effective shear modulus (G') of 6.6 ± 0.2 kPa was found for aspiration of 115 PA particles of ∼10-20 μm diameter. Using a viscoelastic model to describe flow into the pipette, a mean initial effective elastic modulus (E0') of 3.5 ± 1.7 MPa was found for aspiration of 17 PDMS particles of ∼ 9-11 μm diameter. These moduli are consistent with previously reported literature values, providing initial validation of the microaspiration method.
Collapse
Affiliation(s)
- Ankita Gangotra
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand
| | | | | | | | | |
Collapse
|
7
|
Meyer KC, Labriola NR, Darling EM, Kaehr B. Shape-Preserved Transformation of Biological Cells into Synthetic Hydrogel Microparticles. ADVANCED BIOSYSTEMS 2019; 3:e1800285. [PMID: 32627427 PMCID: PMC7747388 DOI: 10.1002/adbi.201800285] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/07/2019] [Indexed: 12/12/2022]
Abstract
The synthesis of materials that can mimic the mechanical, and ultimately functional, properties of biological cells can broadly impact the development of biomimetic materials, as well as engineered tissues and therapeutics. Yet, it is challenging to synthesize, for example, microparticles that share both the anisotropic shapes and the elastic properties of living cells. Here, a cell-directed route to replicate cellular structures into synthetic hydrogels such as polyethylene glycol (PEG) is described. First, the internal and external surfaces of chemically fixed cells are replicated in a conformal layer of silica using a sol-gel process. The template is subsequently removed to render shape-preserved, mesoporous silica replicas. Infiltration and cross-linking of PEG precursors and dissolution of the silica result in a soft hydrogel replica of the cellular template as demonstrated using erythrocytes, HeLa, and neuronal cultured cells. The elastic modulus can be tuned over an order of magnitude (≈10-100 kPa) though with a high degree of variability. Furthermore, synthesis without removing the biotemplate results in stimuli-responsive particles that swell/deswell in response to environmental cues. Overall, this work provides a foundation to develop soft particles with nearly limitless architectural complexity derived from dynamic biological templates.
Collapse
Affiliation(s)
- Kristin C Meyer
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM, 87108, USA
| | - Nicholas R Labriola
- Center for Biomedical Engineering and Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, 02912, USA
| | - Eric M Darling
- Center for Biomedical Engineering and Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, 02912, USA
| | - Bryan Kaehr
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM, 87108, USA
| |
Collapse
|
8
|
Duncan EM, Broderick AC, Fuller WJ, Galloway TS, Godfrey MH, Hamann M, Limpus CJ, Lindeque PK, Mayes AG, Omeyer LCM, Santillo D, Snape RTE, Godley BJ. Microplastic ingestion ubiquitous in marine turtles. GLOBAL CHANGE BIOLOGY 2019; 25:744-752. [PMID: 30513551 PMCID: PMC6849705 DOI: 10.1111/gcb.14519] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/15/2018] [Indexed: 05/18/2023]
Abstract
Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.
Collapse
Affiliation(s)
- Emily M. Duncan
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- College of Life and Environmental Sciences: BiosciencesUniversity of ExeterExeterUK
- Marine Ecology and BiodiversityPlymouth Marine LaboratoryPlymouthUK
| | - Annette C. Broderick
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
| | - Wayne J. Fuller
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Faculty of Veterinary MedicineNear East UniversityNicosiaNorth CyprusTurkey
- Society for Protection of TurtlesKyreniaNorth CyprusTurkey
| | - Tamara S. Galloway
- College of Life and Environmental Sciences: BiosciencesUniversity of ExeterExeterUK
| | | | - Mark Hamann
- College of Science and EngineeringJames Cook UniversityTownsvilleQLDAustralia
| | - Colin J. Limpus
- Department of Environment and ScienceThreatened Species UnitBrisbaneQLDAustralia
| | | | - Andrew G. Mayes
- School of ChemistryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Lucy C. M. Omeyer
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
| | - David Santillo
- Greenpeace Research Laboratories, School of Biosciences, Innovation Centre Phase 2University of ExeterExeterUK
| | - Robin T. E. Snape
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
- Society for Protection of TurtlesKyreniaNorth CyprusTurkey
| | - Brendan J. Godley
- Marine Turtle Research Group, Centre for Ecology and ConservationUniversity of ExeterPenrynUK
| |
Collapse
|
9
|
Shah MK, Leary EA, Darling EM. Integration of hyper-compliant microparticles into a 3D melanoma tumor model. J Biomech 2018; 82:46-53. [PMID: 30392774 DOI: 10.1016/j.jbiomech.2018.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 10/11/2018] [Accepted: 10/17/2018] [Indexed: 12/19/2022]
Abstract
Multicellular spheroids provide a physiologically relevant platform to study the microenvironment of tumors and therapeutic applications, such as microparticle-based drug delivery. The goal of this study was to investigate the incorporation/penetration of compliant polyacrylamide microparticles (MPs), into either cancer or normal human cell spheroids. Incorporation of collagen-1-coated MPs (stiffness: 0.1 and 9 kPa; diameter: 15-30 µm) into spheroids (diameter ∼100 µm) was tracked for up to 22 h. Results indicated that cells within melanoma spheroids were more influenced by MP mechanical properties than cells within normal cell spheroids. Melanoma spheroids had a greater propensity to incorporate and displace the more compliant MPs over time. Mature spheroids composed of either cell type were able to recognize and integrate MPs. While many tumor models exist to study drug delivery and efficacy, the study of uptake and incorporation of cell-sized MPs into established spheroids/tissues or tumors has been limited. The ability of hyper-compliant MPs to successfully penetrate 3D tumor models with natural extracellular matrix deposition provides a novel platform for potential delivery of drugs and other therapeutics into the core of tumors and micrometastases.
Collapse
Affiliation(s)
- Manisha K Shah
- Center for Biomedical Engineering, Brown University, RI, USA
| | | | - Eric M Darling
- Center for Biomedical Engineering, Brown University, RI, USA; Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, RI, USA; Department of Orthopaedics, Brown University, RI, USA; School of Engineering, Brown University, RI, USA.
| |
Collapse
|
10
|
Girardo S, Träber N, Wagner K, Cojoc G, Herold C, Goswami R, Schlüßler R, Abuhattum S, Taubenberger A, Reichel F, Mokbel D, Herbig M, Schürmann M, Müller P, Heida T, Jacobi A, Ulbricht E, Thiele J, Werner C, Guck J. Standardized microgel beads as elastic cell mechanical probes. J Mater Chem B 2018; 6:6245-6261. [PMID: 32254615 DOI: 10.1039/c8tb01421c] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cell mechanical measurements are gaining increasing interest in biological and biomedical studies. However, there are no standardized calibration particles available that permit the cross-comparison of different measurement techniques operating at different stresses and time-scales. Here we present the rational design, production, and comprehensive characterization of poly-acrylamide (PAAm) microgel beads mimicking size and overall mechanics of biological cells. We produced mono-disperse beads at rates of 20-60 kHz by means of a microfluidic droplet generator, where the pre-gel composition was adjusted to tune the beads' elasticity in the range of cell and tissue relevant mechanical properties. We verified bead homogeneity by optical diffraction tomography and Brillouin microscopy. Consistent elastic behavior of microgel beads at different shear rates was confirmed by AFM-enabled nanoindentation and real-time deformability cytometry (RT-DC). The remaining inherent variability in elastic modulus was rationalized using polymer theory and effectively reduced by sorting based on forward-scattering using conventional flow cytometry. Our results show that PAAm microgel beads can be standardized as mechanical probes, to serve not only for validation and calibration of cell mechanical measurements, but also as cell-scale stress sensors.
Collapse
Affiliation(s)
- S Girardo
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Labriola NR, Sadick JS, Morgan JR, Mathiowitz E, Darling EM. Cell Mimicking Microparticles Influence the Organization, Growth, and Mechanophenotype of Stem Cell Spheroids. Ann Biomed Eng 2018; 46:1146-1159. [PMID: 29671154 DOI: 10.1007/s10439-018-2028-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/13/2018] [Indexed: 12/20/2022]
Abstract
Substrate stiffness is known to alter cell behavior and drive stem cell differentiation, though most research in this area has been restricted to traditional, two-dimensional culture systems rather than more physiologically relevant, three-dimensional (3D) platforms. In this study, we utilized polymer-based, cell mimicking microparticles (CMMPs) to deliver distinct, stable mechanical cues to human adipose derived stem cells in 3D spheroid culture to examine changes in adipogenic differentiation response and mechanophenotype. After 21 days of adipogenic induction, spheroids containing CMMPs (composite spheroids) stiffened in accordance with CMMP elasticity such that spheroids containing the stiffest, ~ 10 kPa, CMMPs were over 27% stiffer than those incorporating the most compliant, ~ 0.25 kPa CMMPs. Adipogenically induced, cell-only spheroids were over 180% larger and 50% more compliant than matched controls. Interestingly, composite spheroids cultured without chemical induction factors dissociated when presented with CMMPs stiffer than ~ 1 kPa, while adipogenic induction factors mitigated this behavior. Gene expression for PPARG and FABP4 were upregulated more than 45-fold in adipogenically induced samples compared to controls but were unaffected by CMMP elasticity, attributed to insufficient cell-CMMP contacts throughout the composite spheroid. In summary, mechanically tuned CMMPs influenced whole-spheroid mechanophenotype and stability but minimally affected differentiation response.
Collapse
Affiliation(s)
- Nicholas R Labriola
- Center for Biomedical Engineering, Brown University, 175 Meeting Street, Box G-B397, Providence, RI, 02912, USA
| | - Jessica S Sadick
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, USA
| | - Jeffrey R Morgan
- Center for Biomedical Engineering, Brown University, 175 Meeting Street, Box G-B397, Providence, RI, 02912, USA.,Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, USA.,School of Engineering, Brown University, Providence, RI, USA
| | - Edith Mathiowitz
- Center for Biomedical Engineering, Brown University, 175 Meeting Street, Box G-B397, Providence, RI, 02912, USA.,Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, USA.,School of Engineering, Brown University, Providence, RI, USA
| | - Eric M Darling
- Center for Biomedical Engineering, Brown University, 175 Meeting Street, Box G-B397, Providence, RI, 02912, USA. .,Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, USA. .,School of Engineering, Brown University, Providence, RI, USA. .,Department of Orthopaedics, Brown University, Providence, RI, USA.
| |
Collapse
|
12
|
Labriola NR, Azagury A, Gutierrez R, Mathiowitz E, Darling EM. Concise Review: Fabrication, Customization, and Application of Cell Mimicking Microparticles in Stem Cell Science. Stem Cells Transl Med 2018; 7:232-240. [PMID: 29316362 PMCID: PMC5788880 DOI: 10.1002/sctm.17-0207] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/06/2017] [Indexed: 12/13/2022] Open
Abstract
Stem and non-stem cell behavior is heavily influenced by the surrounding microenvironment, which includes other cells, matrix, and potentially biomaterials. Researchers have been successful in developing scaffolds and encapsulation techniques to provide stem cells with mechanical, topographical, and chemical cues to selectively direct them toward a desired differentiation pathway. However, most of these systems fail to present truly physiological replications of the in vivo microenvironments that stem cells are typically exposed to in tissues. Thus, cell mimicking microparticles (CMMPs) have been developed to more accurately recapitulate the properties of surrounding cells while still offering ways to tailor what stimuli are presented. This nascent field holds the promise of reducing, or even eliminating, the need for live cells in select, regenerative medicine therapies, and diagnostic applications. Recent, CMMP-based studies show great promise for the technology, yet only reproduce a small subset of cellular characteristics from among those possible: size, morphology, topography, mechanical properties, surface molecules, and tailored chemical release to name the most prominent. This Review summarizes the strengths, weaknesses, and ideal applications of micro/nanoparticle fabrication and customization methods relevant to cell mimicking and provides an outlook on the future of this technology. Moving forward, researchers should seek to combine multiple techniques to yield CMMPs that replicate as many cellular characteristics as possible, with an emphasis on those that most strongly influence the desired therapeutic effects. The level of flexibility in customizing CMMP properties allows them to substitute for cells in a variety of regenerative medicine, drug delivery, and diagnostic systems. Stem Cells Translational Medicine 2018;7:232-240.
Collapse
Affiliation(s)
| | - Aharon Azagury
- Department of Molecular PharmacologyPhysiology, and Biotechnology, Brown University, ProvidenceRhode IslandUSA
| | - Robert Gutierrez
- Center for Biomedical Engineering, Brown University, ProvidenceRhode IslandUSA
| | - Edith Mathiowitz
- Center for Biomedical Engineering, Brown University, ProvidenceRhode IslandUSA
- Department of Molecular PharmacologyPhysiology, and Biotechnology, Brown University, ProvidenceRhode IslandUSA
- School of Engineering, Brown University, ProvidenceRhode IslandUSA
| | - Eric M. Darling
- Center for Biomedical Engineering, Brown University, ProvidenceRhode IslandUSA
- Department of Molecular PharmacologyPhysiology, and Biotechnology, Brown University, ProvidenceRhode IslandUSA
- School of Engineering, Brown University, ProvidenceRhode IslandUSA
- Department of OrthopaedicsBrown University, ProvidenceRhode IslandUSA
| |
Collapse
|
13
|
Li M, Dang D, Liu L, Xi N, Wang Y. Atomic Force Microscopy in Characterizing Cell Mechanics for Biomedical Applications: A Review. IEEE Trans Nanobioscience 2017; 16:523-540. [PMID: 28613180 DOI: 10.1109/tnb.2017.2714462] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cell mechanics is a novel label-free biomarker for indicating cell states and pathological changes. The advent of atomic force microscopy (AFM) provides a powerful tool for quantifying the mechanical properties of single living cells in aqueous conditions. The wide use of AFM in characterizing cell mechanics in the past two decades has yielded remarkable novel insights in understanding the development and progression of certain diseases, such as cancer, showing the huge potential of cell mechanics for practical applications in the field of biomedicine. In this paper, we reviewed the utilization of AFM to characterize cell mechanics. First, the principle and method of AFM single-cell mechanical analysis was presented, along with the mechanical responses of cells to representative external stimuli measured by AFM. Next, the unique changes of cell mechanics in two types of physiological processes (stem cell differentiation, cancer metastasis) revealed by AFM were summarized. After that, the molecular mechanisms guiding cell mechanics were analyzed. Finally the challenges and future directions were discussed.
Collapse
|