{"id":"3711df0e-0a80-444e-b4ca-27c824712cb9","arxiv_id":"2608.07777","paper_version":1,"verdict":"REJECT","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":8,"one_line_summary":"A cellular Potts model with deformable nuclei predicts that larger, stiffer nuclei jam cell monolayers by constraining cell shape, and a fitted scaling law connects nuclear morphology to collective diffusion.","lead":"This paper introduces a computer model of cell layers with deformable nuclei, and uses it to argue that nuclear size and stiffness control whether tissues flow or jam. The authors claim a universal relation between nuclear shape, packing, and cell motion, verified in two breast cell lines, but the verification is largely a fit to the same data.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The reported '<5% predictive MAPE' is an in-sample curve fit: Eq. (18) is fit to the same binned data that Eq. (20) evaluates, so the experimental validation does not test the claimed universal morpho-dynamic relation.","rationale":"The paper's central claim is that nuclear morphologies quantitatively control collective dynamics through a universal morpho-dynamic link, 'verified experimentally with striking accuracy.' That verification rests entirely on the MAPE reported in Fig. 3j-k and Sec. IV D 3. Since Eq. (18) is calibrated on the same binned observations that Eq. (20) scores, the <5% MAPE demonstrates only goodness of fit, not predictive power; a sufficiently flexible piecewise-linear model with phi-dependent parameters will fit arbitrary binned trends. The same circularity weakens the simulation collapse, where the functional forms in Eqs. (12)-(17) are fit to the data and open symbols are excluded before the collapse is displayed. I therefore agree with the reader's rejection: the manuscript's main quantitative promise is unsupported as written. I do not see a separate flaw that is more load-bearing than this validation gap. If the hold-out test I propose were to pass, a revised version could be reconsidered; but the current submission does not establish the headline claim. The open-source code and qualitative simulation trends are valuable, but they do not rescue the quantitative claim.","tokens_in":16864,"tokens_out":9586,"duration_ms":87979,"concrete_test":"Perform a hold-out validation on the binned experimental data for each cell line: split the bins (e.g., odd vs even bin indices, or a 50/50 temporal split) so that Eq. (18) is fit only on one subset and MAPE is computed only on the held-out subset. If held-out MAPE exceeds 5% or is substantially worse than the in-sample MAPE, the claim of predictive accuracy is an artifact of in-sample fitting. A useful secondary check is to fit the same model to data with (SN, phi) labels shuffled; if shuffled data also yield <5% in-sample MAPE, the model is too flexible to support the universal-relation claim.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section IV D 3 fits the piecewise-linear Eq. (18) to binned experimental data, with phi-dependent baseline D0(phi), slope a(phi), slope ratio gamma, and breakpoint S*(phi), and then reports MAPE (Eq. 20) between the fitted model and the same i-th bins. This is training error, not a prediction. A flexible piecewise model evaluated on the data used to fit it can achieve <5% MAPE even if no genuine morpho-dynamic relation exists. The abstract and conclusion nevertheless state that the relation is 'verified experimentally with striking accuracy' and could serve as a clinical order parameter. The simulation collapse in Fig. 3g has the same structural weakness: the phi-dependent forms in Eqs. (12)-(17) are fit to the simulation data, with open symbols explicitly excluded from the fit, so the collapse does not independently validate those forms. The mechanistic narrative—nuclear size/stiffness restricts accessible cell shapes and thus mobility—is plausible and qualitatively supported by the simulation trends, but the paper's central quantitative claim of a verified universal relation is not established by the evidence as presented.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper introduces a cellular Potts model with explicitly deformable nuclei to study unjamming in confluent monolayers. Simulations varying nuclear area fraction phi and nuclear stiffness J_int show that larger and stiffer nuclei reduce cell diffusivity, T1 transition rates, and cell shape index. The authors propose an empirical relation between nuclear shape index, nuclear area fraction, and collective diffusion, and report a collapse of simulation data onto a master curve. They further fit a piecewise version of this relation to binned experimental data from MCF-10A and MDA-MB-436 cell monolayers, reporting a mean absolute percentage error (MAPE) below 5% in both cell lines, and interpret the rescaled nuclear shape index as an order parameter for nuclear jamming.","tokens_in":17215,"tokens_out":5957,"duration_ms":54808,"significance":"If the quantitative claims were fully substantiated, the paper would offer a novel mechanistic bridge between nuclear mechanics and tissue-scale rigidity, with potential clinical relevance for cancer prognosis. The open-source simulation and analysis code, the transparency about the fitting procedure in Section IV D, and the qualitative consistency between simulations and two epithelial/mesenchymal cell lines are strengths. However, the central quantitative claims of a verified universal morpho-dynamic relation and a predictive order parameter are currently undermined by in-sample fitting and post-hoc exclusion of data points. The mechanistic narrative is plausible and qualitatively supported, but the evidence as presented does not establish the claimed universal relation.","major_comments":[{"comment":"The reported MAPE values (4.42% for MCF-10A and 1.62% for MDA-MB-436, Fig. 3j,k) are in-sample training errors: Eq. (18) is fitted to the same binned data on which Eq. (20) is evaluated. The abstract's claim that the relation is 'verified experimentally with striking accuracy' is therefore not supported; the fit only shows that the piecewise-linear function with phi-dependent coefficients is flexible enough to approximate the training data. An out-of-sample evaluation (e.g., cross-validation, or fitting on one cell line and predicting the other) is needed to support the predictive claim.","section":"Section IV D 3, Eq. (20)"},{"comment":"The caption of Fig. 3g states that 'open symbols in g were excluded from the fit procedure to accomplish collapse.' Excluding data points that do not collapse, with the stated purpose of achieving collapse, is a post-hoc selection that invalidates the master-curve claim as a test of the proposed relation. The exclusion rule should be specified a priori, and the fit should be reported with and without the excluded points.","section":"Section IV D 1, Fig. 3g caption"},{"comment":"The collapse in Fig. 3g is constructed by fitting phi-dependent parameters D0(phi), a(phi), b(phi), and S*_N(phi) to the simulation data. No independent test of these functional forms is provided, and no derivation from the CPM Hamiltonian is given. The 'order parameter' b(phi)(S_N - S*_N) is therefore a curve-fitting device rather than an independently validated physical quantity. To support universality, the authors should either derive the form from the model or validate it on data not used for fitting.","section":"Section IV D 1, Eqs. (12)-(17)"},{"comment":"The experimental fitting procedure changes the functional forms relative to the simulation relation: S*(phi) is taken to be linear rather than cubic (as in Eq. (17)), and a(phi) uses a free offset sigma in Eq. (19) rather than the geometric anchor phi* = 28^2/30^2 of Eq. (16). While the authors state that these changes are 'consistent with our previous rescaling method,' this means the experimental data do not test the simulation-derived relation; they test a more flexible variant with additional free parameters. The claim of a single universal relation is thereby weakened.","section":"Section IV D 3, Eqs. (18)-(19)"}],"minor_comments":[{"comment":"The phrase 'immanent importance' should read 'imminent importance', and 'diagnosic tool' should be 'diagnostic tool'.","section":"Introduction, page 2"},{"comment":"The caption contains the typo 'nuclera area fractions'; it should be 'nuclear area fractions'.","section":"Fig. 2d caption"},{"comment":"The fitted parameter values in Tables II and III are reported without uncertainties; confidence intervals should be provided, particularly for the parameters used in the collapse.","section":"Table II and Section IV D 1"},{"comment":"The experimental binning procedure uses 20 bins for phi and 40 bins for shape, with a cutoff of at least 100 observations per bin; the sensitivity of the fitted relation to the bin number and threshold should be discussed.","section":"Section IV D 2"},{"comment":"The manuscript does not report the number of experimental cells, tracks, or bins that enter the MAPE calculation; including these numbers would improve reproducibility.","section":"Section IV D 3"}],"recommendation":"major_revision","confidential_remarks":"The paper presents a potentially important mechanistic idea and provides open-source simulation code, but the central quantitative claim of a verified universal order parameter is currently supported only by in-sample curve fitting and post-hoc data exclusion. I would not recommend acceptance until the authors provide a genuine out-of-sample validation and justify or eliminate the excluded points. If such validation cannot be provided, the claims should be substantially softened to describe an empirical fit rather than a verified universal relation. The manuscript may still be suitable for publication after these revisions, depending on the journal's standards for predictive claims."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Here's my read. The deformable-nucleus CPM is a genuine step forward, and the qualitative story — larger and stiffer nuclei constrain accessible cell shapes, which in turn suppresses T1 events and diffusion — is convincing and well supported by the simulation data. The 121 state points with ten repeats each give the central trends solid footing. The connection to the two cell lines is plausible, and the fact that MCF-10A jams while MDA-MB-436 doesn't fits the model's logic.\n\nThe soft spot is exactly where the stress-test note lands. The experimental 'validation' in Section IV D 3 fits Eq. (18) with phi-dependent parameters directly to the binned data, then computes MAPE on those same bins. That is training error, not a prediction, so the claim of 'striking accuracy' in the abstract is not supported. The simulation collapse in Fig. 3g has the same circular structure: D0(phi), a(phi), b/a, and S*_N(phi) are all fit to the simulation data, and some open symbols are explicitly excluded to get the collapse. The functional forms are empirical too; they are not derived from the CPM Hamiltonian. So the universal morpho-dynamic relation is currently a compact description of the data, not an independently verified law.\n\nI wouldn't reject the paper over this. The model and the qualitative mechanism are the real contributions, and they stand. The overclaim is fixable: reframe the quantitative part as an empirical relation, provide a genuine out-of-sample test (train on one cell line, test on the other, or leave out a subset of simulation state points), and tone down the abstract and conclusion. The clinical order-parameter language is premature.\n\nWho should read it: anyone working on CPM or tissue jamming. The model is a useful new tool. I'd bring it to a reading group, and I'd cite the deformable-nucleus CPM in work on collective cell migration. For peer review, yes — this deserves a serious referee, but with the expectation of major revision focused on the validation. I agree with the stress-test's diagnosis; I just think the cure is revision, not rejection.","headline":"Solid modeling core, but the claimed experimental verification of a universal morpho-dynamic relation is in-sample fitting — worth peer review with major revision.","tokens_in":17780,"tokens_out":3041,"would_cite":true,"duration_ms":28251,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper claims that nuclear size and stiffness regulate the jamming-unjamming transition in dense cell sheets by constraining the range of cell shapes a tissue can adopt, so that cell shape is a phenomenological indicator while the…","keywords":["cell unjamming","nuclear mechanics","cellular Potts model","jamming transition","cell shape index","nuclear area fraction","collective cell migration","breast cancer monolayers"],"falsifier":"Grow a confluent monolayer of MCF-10A cells, pharmacologically enlarge nuclei (for example by inhibiting nuclear export) without changing cell-cell adhesion, and measure bin-averaged $D_2^{\\min}$ against nuclear area fraction $\\phi$ and nuclear shape index $S_N$; if the data no longer fall on the paper's rescaled master curve, or if mobility stays constant while the cell shape index distribution is unchanged, the claim that nuclear density constrains cell shape to control unjamming fails.","tokens_in":16651,"feed_emoji":"🧫","tokens_out":9741,"duration_ms":81454,"temperature":0.7,"pith_summary":"The paper claims that the jamming-unjamming transition in dense cell monolayers is controlled at the subcellular level by the nucleus: nuclear area fraction and nuclear stiffness limit the cell shapes a confluent tissue can reach, and cell shape then sets how easily cells exchange neighbours and move. The authors build a cellular Potts model with explicitly deformable nuclei, vary nuclear size and stiffness, and measure the long-time diffusion constant and the rate of T1 neighbour-exchange events. They find that all simulated state points collapse onto a single cell-shape-versus-diffusion master curve, while a rescaled nuclear-shape relation predicts the measured motion of MCF-10A and MDA-MB-436 breast-cell monolayers with a mean absolute percentage error below 5 percent. This matters because it reconciles previously conflicting density-driven and shape-driven views of tissue jamming, and because it suggests that statically measurable nuclear morphology could serve as a physically motivated marker for collective cell motility.","feed_headline":"Nuclear size and stiffness set when cell sheets unjam","feed_subtitle":"A deformable-nucleus model pins tissue fluidity to nuclear shape, matching two breast-cell lines within 5%.","key_machinery":"The load-bearing object is an extended cellular Potts model in which each cell contains an explicitly deformable nucleus, treated as a separate compartment with its own area-conservation term and an internal contact energy $J_{\\mathrm{int}}$ that sets nuclear stiffness; a harmonic spring anchors the nucleus to the cell centre of mass, and an active Brownian force drives cytoplasmic migration. The argument runs on dimensionless shape indices $S = \\langle P/\\sqrt{A}\\rangle$ for cells and nuclei, and on an empirical double-exponential law $D(S_N,\\phi) = D_0(\\phi)\\left[e^{-a(\\phi)(S_N - S_N^*(\\phi))} + e^{-b(\\phi)(S_N - S_N^*(\\phi))}\\right]^{-1}$, whose $\\phi$-dependent parameters (exponential $D_0$, linear $a$ with geometric limit $\\phi^* = 28^2/30^2$, constant $b/a$, cubic $S_N^*$) are fitted to simulations and then used to rescale experimental data onto one master curve. That collapsed curve is the order parameter the paper introduces for nuclear jamming.","core_discovery":"On the paper's own terms, the central discovery is that nuclear mechanics regulates tissue-scale jamming by constraining cell shape: larger nuclear area fraction $\\phi$ and higher internal contact energy $J_{\\mathrm{int}}$ make cells rounder, reduce T1 neighbour exchanges, and lower the long-time diffusion constant $D$, with combined changes lowering $D$ by nearly four orders of magnitude. The authors state the reconciliation directly: while cell shape determines jamming phenomenologically, nuclear density constrains possible cell shapes and thereby regulates the transition at the subcellular scale. Their simulations collapse onto a single cell-shape-diffusion master curve, and a rescaled nuclear-shape-diffusion law $D(S_N, \\phi)$ is verified against MCF-10A and MDA-MB-436 monolayers, predicting measured $D_2^{\\min}$ within 5 percent mean absolute percentage error. The paper therefore claims a universal morpho-dynamic link from statically measurable nuclear morphology to collective cell motion.","pith_inferences":["The paper does not test whether directly softening or shrinking nuclei is sufficient to unjam a monolayer while cell-cell adhesion is held fixed; an experiment with drugs targeting nuclear envelope components would isolate the nuclear contribution from the cytoskeletal one.","Because the geometric bound $\\phi^* = 28^2/30^2$ sets a formal limit at which $a(\\phi)$ vanishes, the model predicts that mobility should drop to zero as the nucleus fills the cell; measuring whether diffusion vanishes near that packing fraction in experiments would test whether the bound is physical or only a fitting constraint.","The double-exponential collapse is an empirical law fitted to cellular Potts model data, not derived from the model Hamiltonian; the same order parameter might survive with a different functional family in three dimensions or in monolayers with heterogeneous nuclear sizes, so the universality claim is only as strong as the persistence of these fitted forms."],"forward_implications":["Increasing nuclear area fraction from $\\phi=0.4$ to $\\phi=0.7$ lowers the long-time diffusion constant by about one order of magnitude, and raising both nuclear size and stiffness together lowers it by almost four orders of magnitude.","T1 neighbour-exchange rate and diffusion constant track each other, so nuclear mechanics controls jamming by throttling the rate at which cells can rearrange.","All simulated state points fall on a single cell-shape-versus-diffusion master curve, making cell shape a universal indicator of tissue fluidity even though the nucleus sets the accessible shape range.","Static nuclear shape and nuclear area fraction predict $D_2^{\\min}$ in MCF-10A and MDA-MB-436 monolayers with a mean absolute percentage error below 5 percent, suggesting a physics-based prognostic marker readable from histological images."],"supporting_citations":[{"why":"Supplies the T1 energy-barrier and cell-shape-index threshold ($S_C \\approx 3.81$) that the paper uses to connect neighbour exchanges to cell shape.","marker":"[5]"},{"why":"Provides the experimental breast-cancer data and the combined cell-nuclear-shape order parameter that motivate and validate the nuclear-jamming relation.","marker":"[10]"},{"why":"Gives the self-propelled Voronoi nucleus-free model of shape-driven jamming that this paper extends by adding deformable nuclei.","marker":"[12]"},{"why":"Is the rigid-nucleus model whose prediction that elongated nuclei promote jamming conflicts with experiments, and which the deformable-nucleus model corrects.","marker":"[14]"},{"why":"Documents that epithelial-mesenchymal transition softens nuclei and promotes unjamming, supporting the assumption that nuclear deformability is biologically relevant.","marker":"[15]"},{"why":"Is the single-cell compartmental cellular Potts model with an elastic nucleus that inspires the confluent-layer model's Hamiltonian.","marker":"[25]"},{"why":"Supplies the perimeter-estimation method and the link between $J_{\\mathrm{int}}$ and nuclear envelope tension used for shape measurement and stiffness interpretation.","marker":"[31]"},{"why":"Is the original cellular Potts model whose Hamiltonian forms the basis of the extended model.","marker":"[36]"}],"fun_headline_variants":["Nuclear shape times unjamming in dense cell sheets","Deformable nuclei control when crowded cells unjam","Nuclei gate the unjamming transition in tissues","Nuclear mechanics switches on collective cell motion","How nuclear size sets the pace for cell unjamming"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the fitted functional forms—double-exponential shape-diffusion decay, exponential $D_0(\\phi)$, linear $a(\\phi)$, constant $b/a$, cubic $S_N^*(\\phi)$, and the geometric upper limit $\\phi^* = 28^2/30^2$—are the true universal relations and not just the best fits within this cellular Potts model family, since the paper gives no derivation of these forms from the model's Hamiltonian.","fun_headline_variants_meta":{"raw":{"variants":["Nuclear shape times unjamming in dense cell sheets","Deformable nuclei control when crowded cells unjam","Nuclei gate the unjamming transition in tissues","Nuclear mechanics switches on collective cell motion","How nuclear size sets the pace for cell unjamming"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000176,"raw_usage":{"total_tokens":1273,"prompt_tokens":912,"completion_tokens":361,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":528,"completion_tokens_details":{"reasoning_tokens":286}},"tokens_in":528,"tokens_out":361,"duration_ms":4337,"temperature":1.0,"reasoning_tokens":286,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T04:12:45.217383+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Grow a confluent monolayer of MCF-10A cells, pharmacologically enlarge nuclei (for example by inhibiting nuclear export) without changing cell-cell adhesion, and measure bin-averaged $D_2^{\\min}$ against nuclear area fraction $\\phi$ and nuclear shape index $S_N$; if the data no longer fall on the paper's rescaled master curve, or if mobility stays constant while the cell shape index distribution is unchanged, the claim that nuclear density constrains cell shape to control unjamming fails.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the T1 energy-barrier and cell-shape-index threshold ($S_C \\approx 3.81$) that the paper uses to connect neighbour exchanges to cell shape."},{"cited_title":"Gottheil, J","cited_arxiv_id":null,"evidence_quote":"Provides the experimental breast-cancer data and the combined cell-nuclear-shape order parameter that motivate and validate the nuclear-jamming relation."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Gives the self-propelled Voronoi nucleus-free model of shape-driven jamming that this paper extends by adding deformable nuclei."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Is the rigid-nucleus model whose prediction that elongated nuclei promote jamming conflicts with experiments, and which the deformable-nucleus model corrects."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Documents that epithelial-mesenchymal transition softens nuclei and promotes unjamming, supporting the assumption that nuclear deformability is biologically relevant."},{"cited_title":"Scianna and L","cited_arxiv_id":null,"evidence_quote":"Is the single-cell compartmental cellular Potts model with an elastic nucleus that inspires the confluent-layer model's Hamiltonian."},{"cited_title":"Magno, V","cited_arxiv_id":null,"evidence_quote":"Supplies the perimeter-estimation method and the link between $J_{\\mathrm{int}}$ and nuclear envelope tension used for shape measurement and stiffness interpretation."},{"cited_title":"Graner and J","cited_arxiv_id":null,"evidence_quote":"Is the original cellular Potts model whose Hamiltonian forms the basis of the extended model."}],"review_version":1}