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Dickinson RB, Lele TP. Nuclear shapes are geometrically determined by the excess surface area of the nuclear lamina. Front Cell Dev Biol 2023; 11:1058727. [PMID: 37397244 PMCID: PMC10308086 DOI: 10.3389/fcell.2023.1058727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 05/30/2023] [Indexed: 07/04/2023] Open
Abstract
Introduction: Nuclei have characteristic shapes dependent on cell type, which are critical for proper cell function, and nuclei lose their distinct shapes in multiple diseases including cancer, laminopathies, and progeria. Nuclear shapes result from deformations of the sub-nuclear components-nuclear lamina and chromatin. How these structures respond to cytoskeletal forces to form the nuclear shape remains unresolved. Although the mechanisms regulating nuclear shape in human tissues are not fully understood, it is known that different nuclear shapes arise from cumulative nuclear deformations post-mitosis, ranging from the rounded morphologies that develop immediately after mitosis to the various nuclear shapes that roughly correspond to cell shape (e.g., elongated nuclei in elongated cells, flat nuclei in flat cells). Methods: We formulated a mathematical model to predict nuclear shapes of cells in various contexts under the geometric constraints of fixed cell volume, nuclear volume and lamina surface area. Nuclear shapes were predicted and compared to experiments for cells in various geometries, including isolated on a flat surface, on patterned rectangles and lines, within a monolayer, isolated in a well, or when the nucleus is impinging against a slender obstacle. Results and Discussion: The close agreement between predicted and experimental shapes demonstrates a simple geometric principle of nuclear shaping: the excess surface area of the nuclear lamina (relative to that of a sphere of the same volume) permits a wide range of highly deformed nuclear shapes under the constraints of constant surface area and constant volume. When the lamina is smooth (tensed), the nuclear shape can be predicted entirely from these geometric constraints alone for a given cell shape. This principle explains why flattened nuclear shapes in fully spread cells are insensitive to the magnitude of the cytoskeletal forces. Also, the surface tension in the nuclear lamina and nuclear pressure can be estimated from the predicted cell and nuclear shapes when the cell cortical tension is known, and the predictions are consistent with measured forces. These results show that excess surface area of the nuclear lamina is the key determinant of nuclear shapes. When the lamina is smooth (tensed), the nuclear shape can be determined purely by the geometric constraints of constant (but excess) nuclear surface area, nuclear volume, and cell volume, for a given cell adhesion footprint, independent of the magnitude of the cytoskeletal forces involved.
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Affiliation(s)
- Richard B. Dickinson
- Department of Chemical Engineering, University of Florida, Gainesville, FL, United States
| | - Tanmay P. Lele
- Department of Biomedical Engineering, College of Engineering, Texas A&M University College Station, College Station, TX, United States
- Artie McFerrin Department of Chemical Engineering, College of Engineering, Texas A&M University, College Station, TX, United States
- Department of Translational Medical Sciences, Texas A&M University, College Station, TX, United States
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Danusso R, Rosati R, Possenti L, Lombardini E, Gigli F, Costantino ML, Ferrazzi E, Casagrande G, Lattuada D. Human umbilical cord blood cells suffer major modification by fixatives and anticoagulants. Front Physiol 2023; 14:1070474. [PMID: 37008002 PMCID: PMC10050555 DOI: 10.3389/fphys.2023.1070474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/28/2023] [Indexed: 03/17/2023] Open
Abstract
Introduction: Developing techniques for the tagless isolation of homogeneous cell populations in physiological-like conditions is of great interest in medical research. A particular case is Gravitational Field-Flow Fractionation (GrFFF), which can be run avoiding cell fixation, and that was already used to separate viable cells. Cell dimensions have a key role in this process. However, their dimensions under physiological-like conditions are not easily known since the most diffused measurement techniques are performed on fixed cells, and the fixation used to preserve tissues can alter the cell size. This work aims to obtain and compare cell size data under physiological-like conditions and in the presence of a fixative.Methods: We developed a new protocol that allows the analysis of blood cells in different conditions. Then, we applied it to obtain a dataset of human cord blood cell dimensions from 32 subjects, comparing two tubes with anticoagulants (EDTA and Citrate) and two tubes with different preservatives (CellRescue and CellSave). We analyzed a total of 2071 cells by using confocal microscopy via bio-imaging to assess dimensions (cellular and nuclear) and morphology.Results: Cell diameter measured does not differ when using the different anticoagulants, except for the increase reported for monocyte in the presence of citrate. Instead, cell dimensions differ when comparing anticoagulants and cell preservative tubes, with a few exceptions. Cells characterized by high cytoplasm content show a reduction in their size, while morphology appears always preserved. In a subgroup of cells, 3D reconstruction was performed. Cell and nucleus volumes were estimated using different methods (specific 3D tool or reconstruction from 2D projection).Discussion: We found that some cell types benefit from a complete 3D analysis because they contain non-spherical structures (mainly for cells characterized by poly-lobated nucleus). Overall, we showed the effect of the preservatives mixture on cell dimensions. Such an effect must be considered when dealing with problems highly dependent on cell size, such as GrFFF. Additionally, such information is crucial in computational models increasingly being employed to simulate biological events.
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Affiliation(s)
- Roberta Danusso
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Riccardo Rosati
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Luca Possenti
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Elena Lombardini
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Francesca Gigli
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Maria Laura Costantino
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Enrico Ferrazzi
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Giustina Casagrande
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Debora Lattuada
- Department of Women-Child-Newborn, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
- *Correspondence: Debora Lattuada,
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Katiyar A, Zhang J, Antani JD, Yu Y, Scott KL, Lele PP, Reinhart‐King CA, Sniadecki NJ, Roux KJ, Dickinson RB, Lele TP. The Nucleus Bypasses Obstacles by Deforming Like a Drop with Surface Tension Mediated by Lamin A/C. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201248. [PMID: 35712768 PMCID: PMC9376816 DOI: 10.1002/advs.202201248] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 05/20/2022] [Indexed: 06/15/2023]
Abstract
Migrating cells must deform their stiff cell nucleus to move through pores and fibers in tissue. Lamin A/C is known to hinder cell migration by limiting nuclear deformation and passage through confining channels, but its role in nuclear deformation and passage through fibrous environments is less clear. Cell and nuclear migration through discrete, closely spaced, slender obstacles which mimic the mechanical properties of collagen fibers are studied. Nuclei bypass slender obstacles while preserving their overall morphology by deforming around them with deep local invaginations of little resisting force. The obstacles do not impede the nuclear trajectory and do not cause rupture of the nuclear envelope. Nuclei likewise deform around single collagen fibers in cells migrating in 3D collagen gels. In contrast to its limiting role in nuclear passage through confining channels, lamin A/C facilitates nuclear deformation and passage through fibrous environments; nuclei in lamin-null (Lmna-/- ) cells lose their overall morphology and become entangled on the obstacles. Analogous to surface tension-mediated deformation of a liquid drop, lamin A/C imparts a surface tension on the nucleus that allows nuclear invaginations with little mechanical resistance, preventing nuclear entanglement and allowing nuclear passage through fibrous environments.
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Affiliation(s)
- Aditya Katiyar
- Department of Biomedical EngineeringTexas A&M University101 Bizzell St.College StationTX77843USA
| | - Jian Zhang
- Department of Biomedical EngineeringVanderbilt University2301 Vanderbilt PlaceNashvilleTN37235USA
| | - Jyot D. Antani
- Artie McFerrin Department of Chemical EngineeringTexas A&M University3122 TAMUCollege StationTX77843USA
| | - Yifan Yu
- Department of Chemical EngineeringUniversity of Florida1030 Center DriveGainesvilleFL32611USA
| | - Kelsey L. Scott
- Enabling Technologies GroupSanford Research2301 East 60th St NSioux FallsSD57104USA
| | - Pushkar P. Lele
- Artie McFerrin Department of Chemical EngineeringTexas A&M University3122 TAMUCollege StationTX77843USA
| | - Cynthia A. Reinhart‐King
- Department of Biomedical EngineeringVanderbilt University2301 Vanderbilt PlaceNashvilleTN37235USA
| | - Nathan J. Sniadecki
- Department of Mechanical EngineeringDepartment of Lab Medicine and PathologyInstitute for Stem Cell and Regenerative MedicineCenter for Cardiac BiologyUniversity of WashingtonStevens Way, Box 352600SeattleWA98195USA
| | - Kyle J. Roux
- Enabling Technologies GroupSanford Research2301 East 60th St NSioux FallsSD57104USA
- Department of PediatricsSanford School of MedicineUniversity of South Dakota414 E Clark StVermillionSD57069USA
| | - Richard B. Dickinson
- Department of Chemical EngineeringUniversity of Florida1030 Center DriveGainesvilleFL32611USA
| | - Tanmay P. Lele
- Department of Biomedical EngineeringTexas A&M University101 Bizzell St.College StationTX77843USA
- Artie McFerrin Department of Chemical EngineeringTexas A&M University3122 TAMUCollege StationTX77843USA
- Department of Translational Medical SciencesTexas A&M University2121 W Holcombe St.HoustonTX77030USA
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Yang Z, Zhang L, Lv N, Song C, Wang H, Luo L, Yuan L, Zhao H. Accurate 3D morphological computational model reconstruction of suspended cells imaged through stratified media by the precise depth-varying point spread function method. OPTICS EXPRESS 2022; 30:27539-27559. [PMID: 36236923 DOI: 10.1364/oe.465309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/05/2022] [Indexed: 06/16/2023]
Abstract
Accurate three-dimensional (3D) morphological computational models of cells are important in a number of biological studies. This study proposes a precise depth-varying point spread function (PDV-PSF) method for reconstructing 3D computational models of suspended cells from two-dimensional (2D) confocal image stacks. Our approach deblurs the 2D images in horizontal plane and corrects the deformation in vertical direction to overcome the refractive index mismatch problem caused by suspended cells imaging through stratified media. Standard fluorescent polystyrene spheres and Jurkat T-lymphocytes are selected to evaluate the validity and accuracy of this PDV-PSF method. Qualitative and quantitative results demonstrate that our approach has superior performance in 3D morphological computational models reconstruction of suspended cells.
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