scCLIP: A contrastive masked-reconstruction framework for paired single-cell multi-omics integration.

Xu, Xiang; Du, Li · J Biomed Inform · 2026

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Abstract

Paired biomedical assays increasingly measure different molecular or clinical views from the same sample. The statistical problem is simple to state but hard to solve: the views often have different dimensions, noise models, and dynamic ranges, yet downstream analysis requires a common representation. Single-cell CITE-seq is a useful example because transcript counts and surface-protein abundances are observed in the same cell. Existing paired-omics methods, including probabilistic models, matrix-factorization approaches, and neural fusion models, have addressed this setting with different assumptions. Fewer studies, however, have asked whether a symmetric contrastive objective can align the two views while retaining modality-specific signal through reconstruction. We present scCLIP, a contrastive masked-reconstruction framework for paired single-cell multi-omics integration. scCLIP trains RNA and ADT branches jointly with a bidirectional cross-modal contrastive loss and masked reconstruction losses. The branches use the same architectural template but retain separate input/output adapters, encoder-decoder parameters, and projection heads; the projected embeddings are compared in an ℓ<sub>2</sub>-normalized space with a learnable logit scale. We evaluate scCLIP on five paired RNA-protein datasets, where it is compared against TotalVI, BREMSC, jointDIMMSC, scMM, and SCOIT and achieves the highest ARI and FMI on every dataset (with TotalVI second-best overall and marginally higher NMI on three of the five datasets), and on the larger NeurIPS 2021 BMMC CITE-seq benchmark (90,261 cells, 134 proteins, 45 cell types) where scCLIP scales without architectural change and produces strong batch mixing on a 12-batch dataset. We additionally provide direct evidence of RNA-ADT alignment through retrieval and distance-based alignment metrics, and report standard batch-mixing scores on the NeurIPS embedding. The results support scCLIP as a reusable paired-view representation-learning template, with RNA-protein integration serving as the primary empirical testbed. The source code and an end-to-end tutorial for applying scCLIP to new CITE-seq data are publicly available at https://github.com/xubohao39-cyber/scCLIP.