PaSTel: Anchoring Histology in Spatial Transcriptomics via Multi-Scale Hierarchical Bio-Prior Contrastive Pretraining
This study addresses the limitations of weak gene discriminability and neglected spatial dependencies in spatial transcriptomics pre-training by proposing PaSTel, a hierarchical multimodal framework. This method introduces a novel three-scale biologically informed contrastive learning mechanism spanning point, functional, and regional levels. By integrating TF-IDF reweighting, KEGG pathway anchoring, and spatial clustering, PaSTel achieves deep alignment between histology and gene expression. Experimental results demonstrate that PaSTel consistently outperforms existing vision and omics encoders across multiple downstream tasks. Crucially, this approach effectively bridges the gap between global semantics and spatial structure, significantly enhancing both representation informativeness and transferability for spatial transcriptomic analysis.