Organizations: Universiti Sains Malaysia · The Chinese University of Hong Kong Shenzhen · Shenzhen Loop Area Institute · Shenzhen Research Institute of Big Data · University of Electronic Science and Technology of China · King Abdullah University of Science and Technology
Destructive single-cell measurements provide unpaired population snapshots rather than observations of the same cells across conditions. Local cell states and transition requests may also be insufficient to distinguish responses across source populations. We introduce TempoBridge, a common source-conditioned transport formulation for temporal, genetic, and chemical population transitions. Source cells initialize latent transport and provide a fixed empirical population summary. The velocity field receives this summary alongside the evolving cell state, flow time, and a structured transition descriptor. Minibatch optimal transport (OT) supplies couplings only for conditional flow-matching training paths; inference requires neither target expression nor OT computation. On held-out donors, TempoBridge achieves an Energy distance of 0.129 versus 0.144 for scGen. Genetic mean-expression L2 error is 2.261 versus 3.156 for scGPT-scratch under Seen 2/2. On held-out compounds, condition-averaged drug-effect correlation is 0.598 versus 0.561 for the CellFlow adapter. Temporal ablations show higher mean distributional error after removing source context, replacing optimal transport with random pairing, or replacing flow matching with static residual regression. Together, these results demonstrate the predictive utility of a common source-conditioned transport formulation across held-out donors, gene combinations, and compounds.
Figures & tables
Figure 1: TempoBridge overview. (a) Temporal, genetic, and drug-response models use a common source-conditioned transport formulation and are trained independently. (b) Source cells initialize latent particles and provide a fixed empirical population summary. The velocity field takes the evolving latent state, flow time, source summary, and encoded transition descriptor as inputs. Each task model has its own expression decoder. Minibatch OT constructs training paths; inference requires no target expression or OT computation.
Method
MMD ↓
Energy ↓
Δr↑
DE@100 ↑
scGen
0.4300±0.0072
0.1442±0.0019
0.6168±0.0049
0.5111±0.0043
Conditional VAE ( 2015 )
0.4243±0.0023
0.1462±0.0006
0.5826±0.0011
0.4532±0.0053
Conditional MLP
0.4302±0.0032
0.1507±0.0021
0.5742±0.0040
0.4448±0.0070
CellOT
0.4459±0.0105
0.1521±0.0022
0.5849±0.0053
0.4579±0.0082
PRESCIENT
0.4967±0.0052
0.1635±0.0035
0.6210±0.0064
0.5220±0.0035
scNODE
0.5628±0.0018
0.2294±0.0059
0.3543±0.0449
0.3316±0.0327
Table 1: Temporal differentiation on 15 held-out donors, covering 30 prediction requests in the 2,009-gene evaluation space. Scores are aggregated across donors and requested times within each run. Entries report mean ± standard deviation over three randomized test runs with fixed trained models.
Seen 2/2
Seen 1/2
Seen 0/2
Seen 0/1
20 conditions
20 conditions
16 conditions
11 conditions
Method
L2 ↓
Δr↑
L2 ↓
Δr↑
L2 ↓
Δr↑
L2 ↓
Δr↑
Control
5.6384
0.0011
5.5351
0.0114
4.7860
0.0110
3.5682
0.0113
Additive
3.6163
0.8719
NA
NA
NA
scGPT-scratch
3.1564
0.8635
4.1885
0.6614
4.1235
0.5237
3.4632
0.4203
GEARS
3.8881
0.7330
4.7681
0.4596
4.2786
0.5081
3.4356
0.3338
Table 2: Genetic prediction by holdout setting. Means use the test-repeat protocol in Section 5.1 ; each setting weights its conditions equally. Additive applies only to Seen 2/2; NA denotes an inapplicable comparison. Bold marks the best mean within each setting and metric. Complete metrics are in Table S2 .
Method
Mean L2 ↓
Δr↑
pEnergy ↓
pMMD ↓
DE@100 ↑
Conditional MLP
4.8777 ± 0.0455
0.2254 ± 0.0190
0.2260 ± 0.0095
0.0317 ± 0.0005
0.3215 ± 0.0228
CFM without OT
4.6357 ± 0.0285
0.3848 ± 0.0056
0.2219 ± 0.0094
0.0345 ± 0.0027
0.2626 ± 0.0054
chemCPA adapter
5.5117 ± 0.1670
0.3827 ± 0.0122
0.3484 ± 0.0358
0.0437 ± 0.0029
0.5139 ± 0.0098
scDFM adapter
7.7612 ± 0.5215
0.2293 ± 0.0220
0.8281 ± 0.1396
0.0747 ± 0.0079
0.5579 ± 0.0034
CellFlow adapter
4.2875 ± 0.0125
0.5608 ± 0.0002
9.2228 ± 0.0121
0.2714 ± 0.0001
0.3465 ± 0.0002
TempoBridge
4.2478 ± 0.0470
0.5977 ± 0.0047
0.2123 ± 0.0193
0.0327 ± 0.0036
0.5471 ± 0.0129
Table 3: Unseen-compound response prediction on sci-Plex3 (248 equally weighted test conditions). Values are mean ± sample SD over fixed-checkpoint test repeats (Section 5.1 ). pEnergy and pMMD use a common 50-dimensional Gaussian random projection (seed 42), with MMD bandwidth calibrated on training data. Baseline adapters are project implementations; bold marks the best mean in each column.
Model or setting
Branch acc. (%) ↑
Energy ↓
No context
50.00±0.00
0.4575±0.0012
Swapped context
1.96±0.40
3.3299±0.1760
TempoBridge
98.04±0.40
0.0054±0.0004
Table 4: Controlled source-dependent transition ambiguity. Results are mean ± sample SD across three test runs of one fixed checkpoint per trained arm. Branch accuracy evaluates shared synthetic cells; Energy evaluates the full population. Correct and swapped contexts use the same TempoBridge checkpoint.
Appendix figures & tables22 assets
Supplementary material from the paper’s appendix.
Appendix
Task
Source population
Transition descriptor
Target population and evaluation setting
Temporal differentiation
Day 0 cells from a held-out donor
Requested target time
Day 1 or Day 2 population of the same donor
Genetic perturbation
Fixed K562 control population
Unordered set of one or two perturbed genes
Perturbed population under controlled component exposure
Drug response
Matched vehicle-control population
Molecular description, dose, treatment time, and cell line
Treated population for a compound excluded from training and validation
Appendix
Table S1: Task-specific instances of the conditional population prediction problem. Each task uses an independently trained model and its own gene space. The tasks share a common formulation, but not model parameters.
Method
Mean L2 ↓
Δr↑
Energy ↓
DE ρ↑
Seen 2/2: 20 test conditions
Control
5.6384
0.0011
1.8371
0.0378
Additive
3.6163
0.8719
0.9871
0.8956
scGPT-scratch
3.1564
0.8635
7.8094
0.9034
GEARS
3.8881
0.7330
0.9807
0.7925
CPA
5.0754
0.4594
7.2051
0.6198
Appendix
Table S2: Complete genetic metrics by holdout setting. For learned methods, each entry is the mean across test seeds 42, 123, and 2026 using the fixed checkpoint for that training setting, after condition-level averaging within each test run. Control and Additive are deterministic. Additive uses the observed single-gene responses and applies only to Seen 2/2. NA denotes an undefined metric for Control or an inapplicable comparison for Additive. Bold marks the best mean for each setting and metric. Seen 0/1 reuses the Seen 0/2 checkpoints. Control copies a target-sized prefix of the fixed source panel; its effect correlations exclude undefined values, as detailed in Appendix D.6 .
Method
Mean L2 ↓
Δr↑
Energy ↓
DE ρ↑
Control
4.8819
0.0087
1.4380
NA
scGPT-scratch
3.7329
0.6172
7.9229
0.7474
GEARS
4.0926
0.5086
1.0400
0.6848
CPA
5.1841
0.3684
7.5142
0.5636
CellFlow
3.8961
0.6158
2.8048
0.7089
scDFM
4.5115
0.5608
1.2054
0.6945
Appendix
Table S3: Genetic perturbation prediction averaged over four settings: Seen 2/2 (two seen genes; 20 conditions), Seen 1/2 (one seen and one unseen gene; 20 conditions), Seen 0/2 (two unseen genes; 16 conditions), and Seen 0/1 (one unseen gene; 11 conditions). For each method and metric, the reported value is the arithmetic mean of the four setting-level scores, giving each setting equal weight. Each setting-level score first averages test conditions within each run, then averages test seeds 42, 123, and 2026 using one fixed checkpoint per learned method and training setting. Only means are reported; no cross-setting SD is computed. DE ρ denotes Spearman correlation between predicted and observed log-fold changes on reference DE genes. Control is deterministic; NA indicates an undefined four-setting average. Additive is reported in Table S2 for Seen 2/2; its four-setting average is not defined. Seen 0/1 reuses the Seen 0/2 checkpoints without retraining.
Variant
MMD ↓
Energy ↓
Δr↑
DE@100 ↑
Random-pairing flow
0.4145±0.0340
0.1446±0.0063
0.6080±0.0102
0.5316±0.0116
Static OT residual
0.3848±0.0207
0.1350±0.0049
0.6159±0.0105
0.5071±0.0105
Full flow + OT
0.3626±0.0143
0.1291±0.0047
0.6284±0.0115
0.5624±0.0110
Appendix
Table S4: Temporal transport-formulation comparisons under the same donor, gene-space, and evaluation protocol as Table 1 . Entries report mean ± sample SD over three randomized test runs of one fixed checkpoint per variant (test seeds 42, 123, and 2026), using the same run-level aggregation as the temporal main comparison.
Task
Context from source cells
Structured descriptor fields
Not supplied as predictor input
Temporal
Day 0 population from the requested donor
Endpoint times; requested time through the integration horizon
Donor identity; replicate label
Genetic
Matched K562 control population
Perturbed genes; control/single/combination type
Combination identity hash; replicate label
Drug
Matched vehicle-control population
Molecular feature, dose, treatment time, cell line
Drug identity in the unseen-compound setting; replicate label
Appendix
Table S5: Conditioning interface used by the three task instances.
Component
Setting
Expression encoder; cell latent
MLP 5041→512→256
Decoder
MLP 256→512→5041 ; Softplus
Perturbation representation
Separate 512-dimensional gene embeddings; mean pooling
8 conditions; 128 source and target cells per record
Appendix
Table S6: Shared configuration for the nine genetic runs. Each holdout regime is trained independently with seeds 42, 123, and 2026.
Task
Genes
Latent
Source encoder
Solver
Steps
Temporal
2,009
256
Trainable
Heun
32
Genetic
5,041
256
Trainable
Euler
8
Drug
2,000
512
Frozen in stage B
Heun
16
Appendix
Table S7: Task-specific representation and inference settings.
Metric
Seed 42
Seed 123
Seed 2026
Mean
SD
L2 ↓
4.515
4.498
4.513
4.509
0.010
MSE ↓
0.011
0.011
0.011
0.011
<0.001
MAE ↓
0.074
0.074
0.075
0.074
<0.001
Gene r↑
0.976
0.976
0.977
0.976
<0.001
Δr↑
0.418
0.417
0.441
0.425
0.014
DE ρ↑
0.340
0.285
0.277
0.301
0.034
Appendix
Table S8: Seed-level Stage-B results for TempoBridge on the compound-disjoint sci-Plex3 split, using a shared frozen seed-42 expression backbone and condition warm-start. Checkpoints were selected on validation data before evaluation on the compound-disjoint split. Each seed’s score weights conditions equally; SD is the sample SD across the three training seeds, not a compound-bootstrap interval.
Method
pEnergy ↓
pMMD ↓
L2 ↓
Δr↑
DE@100 ↑
Var. r↑
Cov. r↑
Stage-B TempoBridge
0.197 ± 0.010
0.031 ± 0.001
4.509 ± 0.010
0.425 ± 0.014
0.267 ± 0.013
0.909 ± 0.003
0.219 ± 0.002
Main-pipeline TempoBridge
0.212 ± 0.019
0.033 ± 0.004
4.248 ± 0.047
0.598 ± 0.005
0.547 ± 0.013
0.908 ± 0.004
0.221 ± 0.001
Conditional MLP
0.226 ± 0.010
0.032 ± 0.001
4.878 ± 0.046
0.225 ± 0.019
0.322 ± 0.023
0.937 ± 0.000
0.343 ± 0.001
Conditional CFM (no OT)
0.222 ± 0.009
0.034 ± 0.003
4.636 ± 0.029
0.385 ± 0.006
0.263 ± 0.006
0.904 ± 0.002
0.217 ± 0.019
Appendix
Table S9: Drug-response main evaluation and supplementary Stage-B analysis. All rows weight biological conditions equally. The Stage-B row averages transition modules fitted with training seeds 42, 123, and 2026 on a shared frozen seed-42 expression backbone and condition warm-start. The main-pipeline and baseline rows evaluate one fixed checkpoint per method with test seeds 42, 123, and 2026, as in Table 3 ; the main-pipeline row additionally reports variance and covariance correlations. Their SDs describe training-seed and test-run variation, respectively. Cross-row differences do not isolate an OT component effect.
Arm
pEnergy ↓
pMMD ↓
L2 ↓
Δr↑
DE ρ↑
DE@100 ↑
Full
0.197 ± 0.010
0.031 ± 0.001
4.509 ± 0.010
0.425 ± 0.014
0.301 ± 0.034
0.267 ± 0.013
No source context
0.193 ± 0.005
0.031(SD<0.001)
4.506 ± 0.017
0.422 ± 0.004
0.289 ± 0.046
0.261 ± 0.003
No cell line
0.195 ± 0.003
0.031(SD<0.001)
4.539 ± 0.006
0.414 ± 0.003
0.295 ± 0.055
0.260 ± 0.005
Neither
0.196 ± 0.004
0.031(SD<0.001)
4.538 ± 0.008
0.415 ± 0.004
0.295 ± 0.052
0.270 ± 0.003
Appendix
Table S10: Matched 2×2 conditioning ablation on compound-disjoint sci-Plex3 in the fixed-backbone Stage-B setting. (a) Equal condition weights within each training seed; mean ± sample SD over seeds 42, 123, and 2026. (b) Compound-weighted paired differences, Full minus No source context, with their 95% intervals; positive values favor Full. These differences use compound weights and are not obtained by subtracting the displayed condition-weighted means. Removing a condition replaces its vector with zeros without changing model capacity.
Evaluation space
Energy win rate
Mean Energy reduction
MMD win rate
Gaussian 20D
100.000%
7.530%
20.000%
Gaussian 50D
100.000%
8.280%
40.000%
Gaussian 100D
100.000%
9.640%
60.000%
Gaussian 200D
100.000%
10.800%
40.000%
All 22 spaces
95.500% (21/22)
8.180%
36.400% (8/22)
Appendix
Table S11: Fixed-backbone TempoBridge projection-space sensitivity relative to Conditional MLP. Each Gaussian dimension uses five train-only projection seeds. The final row also includes PCA-50 and PCA-100.
Method
L2 ↓
Δr↑
DE ρ↑
pMMD ↓
pEnergy ↓
TempoBridge
4.677
0.414
0.161
0.034
0.223
Conditional CFM (no OT)
4.793
0.387
0.171
0.035
0.242
Conditional MLP
5.060
0.239
0.361
0.034
0.259
Fingerprint KNN
5.187
0.225
0.388
0.037
0.279
chemCPA adapter
5.620
0.368
0.386
0.046
0.386
Appendix
Table S12: Supplementary scaffold-disjoint evaluation for seed 42. The test split contains 17 compounds and 220 biological conditions. This single-seed analysis is not used for the main compound-disjoint claim.
Metric
Full context
No context
Relative change
Formal MMD ↓
0.378 ± 0.021
0.397 ± 0.048
4.720%
Energy ↓
0.135 ± 0.005
0.139 ± 0.013
3.100%
Δ Pearson ↑
0.625 ± 0.005
0.639 ± 0.010
-2.170%
Variance Pearson ↑
0.622 ± 0.010
0.613 ± 0.047
1.620%
Covariance Pearson ↑
0.419 ± 0.006
0.421 ± 0.005
-0.470%
DE@100 ↑
0.515 ± 0.005
0.529 ± 0.007
-2.730%
Appendix
Table S13: Separately matched source-context ablation on the 15-donor temporal cohort in the 2,009-gene space. Both arms were retrained under the same training configuration and seeds, independently of the main-table models; the only difference is whether the pooled source context is supplied. Values are mean ± sample standard deviation over three training seeds. Relative change is signed so that positive values favor the full-context arm.
Metric
Correct
Incorrect mean
Effect
95% CI
Donors won
Energy ↓
0.138
0.142
0.004
[0.002,0.007]
12/15
Formal MMD ↓
0.385
0.392
0.007
[0.004,0.009]
12/15
Δr↑
0.627
0.616
0.011
[0.003,0.021]
11/15
DE@100 ↑
0.512
0.503
0.009
[0.004,0.014]
12/15
Appendix
Table S14: Temporal donor context-swap intervention. The correct context is compared with the mean over the 14 incorrect donor contexts while query cells, requested time, checkpoint, decoder, and target remain fixed within each donor/day/seed comparison. Effects average the two days and evaluations with seeds 42, 123, and 2026, and are reported in the direction favoring the correct context; intervals use donor-level paired bootstrap conditional on the fitted checkpoints and context bank.
Method
Energy ↓
Formal MMD ↓
Sink. ↓
Gene r↑
scVIDR (time-adapted)
0.294±0.005
0.476±0.006
0.195±0.002
0.726±0.005
Appendix
Table S15: Auxiliary 2,009-gene result for the time-adapted scVIDR implementation on the fixed 15-donor cohort with target-matched cardinality. Values follow the main temporal test-repeat protocol: mean ± sample standard deviation over test seeds 42, 123, and 2026.
Method
Energy ↓
Formal MMD ↓
Gene r↑
Var. r↑
DE@100 ↑
Endpoint interpolation
0.225
0.364
0.755
0.632
0.699
PCA interpolation
0.290
0.466
0.724
0.598
0.688
Appendix
Table S16: Non-deployable endpoint references. Both methods read held-out Day 3 expression and are excluded from the external-method ranking.
Energy ↓
Formal MMD ↓
DE@100 ↑
Method
Day 1
Day 2
Day 1
Day 2
Day 1
Day 2
TempoBridge Full Flow
0.131 ± 0.006
0.128 ± 0.004
0.373 ± 0.015
0.353 ± 0.014
0.501 ± 0.013
0.624 ± 0.009
Random-pairing Flow
0.149 ± 0.007
0.140 ± 0.005
0.429 ± 0.037
0.401 ± 0.031
0.426 ± 0.014
0.637 ± 0.010
Static OT residual
0.131 ± 0.002
0.139 ± 0.008
0.385 ± 0.017
0.385 ± 0.024
0.401 ± 0.016
0.614 ± 0.009
Appendix
Table S17: Request-time decomposition in the 2,009-gene space on the fixed 15-donor cohort. Within each randomized test run, metrics are averaged equally across the 15 donor-specific requests at each day. Values are mean ± sample standard deviation over three randomized test runs of one fixed checkpoint per variant (test seeds 42, 123, and 2026), matching the main temporal evaluation.
Steps / calls
Energy ↓
Formal MMD ↓
Time (s) ↓
4 / 8
0.259
0.405
0.087
8 / 16
0.259
0.405
0.126
16 / 32
0.259
0.405
0.211
32 / 64
0.259
0.405
0.363
Appendix
Table S18: Heun solver sensitivity for a frozen seed-42 Full Flow checkpoint on three validation donors (six requests), scored on the fixed 2,009-gene panel with target-matched cardinality. Scores average the six requests. One Heun step uses two velocity-network evaluations. Timing is seconds per 1,000 generated cells.
Arm
Seed
Dctx
Sctx
Shared error
Branch acc.
Energy
MMD
Descriptor-only
42
0.000
0.000
2.001
0.500
0.457
0.273
123
0.000
0.000
2.001
0.500
0.456
0.273
2026
0.000
0.000
2.001
0.500
0.459
0.272
31415
0.000
0.000
2.001
0.500
0.458
0.272
27182
0.000
0.000
2.000
0.500
0.457
0.272
Swapped context
42
3.899
-3.882
3.941
0.013
3.430
0.779
Appendix
Table S19: Checkpoint-level results for the controlled source-context experiment. Seed indexes five training checkpoints, separately from the fixed-model randomized test repeats in Table 4 . Branch accuracies are tabulated as fractions. Sctx is a post hoc directional metric computed from fixed predictions without retraining or checkpoint reselection.
Figure S1: Velocity fields at τ=0.5 for seed 42. The context-free field is identical for A and B at a shared state; empirical contexts produce distinct fields, and exchanging the context input exchanges the field. These are diagnostics in the controlled synthetic latent system.
Figure S2: Model trajectories of the identical shared source states for seed 42. TempoBridge separates the requested branches, while the context-free model overlaps and swapped context reverses the separation. The curves are synthetic ODE trajectories, not reconstructed biological lineages.
Figure S3: Velocity y -component at the identical state z⋆=(0,0) across flow time for seed 42. The context-free field returns identical velocities for A and B. TempoBridge assigns opposite directions, and swapping the empirical contexts reverses them. Dashed lines mark reference shared-component centroid displacements +2 and −2 over the unit transport interval, not exact conditional velocities at every probed time.