Single-cell isolation from heterogeneous populations enables detailed characterization of individual cells. While high-throughput microfluidic techniques are commonly used [1], conventional methods often struggle to support multi-step biochemical reactions while maintaining genetic integrity. To address this, we explore a semi-permeable capsule-based approach in which the capsules retain genetic material while allowing the diffusion of small molecules [2], [3]. A representative image of a microcapsule hosting a cell is shown in Figure 1A. This method is particularly appealing for analyzing biological systems in a cost-effective manner.
We applied capsule-based technology to perform (i) single-cell marker gene analysis and (ii) 3D cell cultivation. Marker gene expression was assessed using cDNA synthesis, PCR, and fluorescent in situ hybridization (FISH) for housekeeping genes, with further optimization needed for specific markers. Additionally, we demonstrated that the capsules support long-term cell growth. For example, suspension cells (K562) proliferated within the capsules for 18 days, eventually filling the entire capsule volume and also expanding the capsule. Adhesive (HeLa) cells adhered to the inner surface of the capsules and remained there long-term, indicating a supportive microenvironment.
This work shows that semi-permeable capsule technology represents a promising tool for single-cell gene expression analysis and controlled growth in 3D microenvironment, with broader potential applications in spheroid formation, drug screening, and high-throughput single-cell studies.
