Milk Extracellular Vesicle Uptake in Porcine ISC Organoid Mo
2026-05-18
Comprehensive Investigation of Milk-Derived Extracellular Vesicle Uptake in Porcine Intestinal Stem Cell Organoids
Study Background and Research Question
Extracellular vesicles (EVs) are nano-sized, membrane-bound particles that mediate intercellular communication by transporting proteins, nucleic acids, and metabolites. Milk-derived extracellular vesicles (MEV) have emerged as promising candidates for studying physiological regulation in the gastrointestinal tract, due to their stability, scalability, and bioactivity (paper). While MEV effects have been explored in immortalized cell lines and animal models, the functional consequences and uptake mechanisms within physiologically relevant intestinal stem cell (ISC)-based models remain poorly defined. Given the limitations of traditional cell lines in capturing the complexity of intestinal epithelium, this study sought to address two major questions: (1) How are MEV internalized by different ISC-derived organoid models? (2) What are the functional outcomes of MEV uptake on ISC stemness and differentiation?Key Innovation from the Reference Study
This work is among the first to systematically establish and utilize three types of porcine ISC-based organoid models—basal-out organoids, organoid monolayers, and apical-out organoids—from distinct intestinal regions (duodenum, jejunum, ileum, and colon). By directly comparing these models, the study uncovers region- and polarity-specific differences in MEV uptake and downstream effects on gene expression related to stemness and epithelial differentiation (paper). Importantly, the research demonstrates that only apical-out organoids and organoid monolayers, which expose the apical surface of intestinal epithelial cells (IEC), can efficiently internalize MEV. This contrasts with basal-out organoids, highlighting the necessity of model selection for studying uptake mechanisms. Furthermore, the use of endocytosis inhibitors confirms that MEV internalization is an active, endocytosis-mediated process.Methods and Experimental Design Insights
The study's methodological rigor is evident in its multistep experimental design:- Model Establishment: ISC-based organoid models were generated from the small intestine and colon of suckling piglets. Three configurations were created: basal-out organoids (classic 3D), organoid monolayers (2D), and apical-out organoids (3D with reversed polarity).
- MEV Isolation: Porcine MEV were isolated using differential ultracentrifugation from milk collected at 10–14 days postpartum, ensuring freshness and minimizing degradation (paper).
- Characterization: The models were validated for physiological relevance by assessing cell lineage composition, epithelial barrier integrity, and fatty acid uptake.
- Functional Assays: Uptake of MEV was visualized and quantified in each organoid configuration. The use of endocytosis inhibitors (including pharmacological agents targeting dynamin-dependent and clathrin-mediated pathways) provided mechanistic insight into the cellular uptake process.
- Gene Expression Analysis: The impact of MEV on ISC stemness and differentiation was evaluated by measuring the expression of key marker genes in colon-derived ISCs.
Protocol Parameters
- assay | MEV isolation via ultracentrifugation | 100,000 × g, 70 min | applicable for extracting EVs from milk with high purity | standard for EV studies | paper
- assay | Organoid culture duration | 7–10 days | optimal for crypt-villus architecture formation | mimics stem cell niche and intestinal physiology | paper
- assay | Endocytosis inhibition | use of dynamin inhibitors (e.g., MitMAB) at 5–30 μM | suitable for blocking dynamin-dependent uptake in organoid models | validated in endocytosis studies; concentration range from prior literature | workflow_recommendation
- assay | MEV uptake quantification | fluorescence microscopy and flow cytometry | enables assessment of internalization rates in different organoid types | distinguishes between apical and basal entry pathways | paper
Core Findings and Why They Matter
The investigation yielded several notable discoveries:- Polarity-Dependent Uptake: Only organoid monolayers and apical-out organoids, with exposed apical surfaces, internalized MEV. Basal-out organoids did not show significant uptake, emphasizing the importance of epithelial polarity in vesicle entry (paper).
- Region-Specific Effects: MEV uptake and functional outcomes varied between intestinal regions, indicating that both tissue origin and epithelial configuration influence MEV-IEC interactions.
- Endocytosis as the Primary Uptake Mechanism: The application of endocytosis inhibitors significantly suppressed MEV internalization, supporting the role of dynamin-dependent endocytosis in vesicle entry. This mechanistic insight aligns with other research utilizing dynamin GTPase activity inhibitors such as N,N,N-trimethyltetradecan-1-aminium bromide (MitMAB) (internal article).
- Gene Expression Modulation: MEV exposure promoted the expression of genes associated with ISC stemness and differentiation, particularly in colon-derived models. This suggests a role for MEV in maintaining epithelial renewal and functional diversity (paper).
Comparison with Existing Internal Articles
Internal resources corroborate and extend the reference paper's observations. For instance, the article "MitMAB: Precision Inhibition of Dynamin in Endocytosis Studies" details the use of N,N,N-trimethyltetradecan-1-aminium bromide (MitMAB) as a specific inhibitor of dynamin GTPase activity, supporting mechanistic dissection in organoid systems (internal article). Similarly, "Milk-Derived Extracellular Vesicle Uptake in ISC Organoid Models" emphasizes the importance of region- and polarity-specific uptake mechanisms and suggests methodological benchmarks for membrane remodeling studies (internal article). These internal articles collectively reinforce the conclusion that advanced organoid models provide unique insights into cellular uptake mechanisms not achievable in conventional 2D cultures. They also highlight the utility of targeted endocytosis inhibitors in elucidating membrane trafficking pathways.Limitations and Transferability
While the study establishes robust ISC-based organoid models and provides compelling evidence for polarity- and region-specific uptake of MEV, several limitations must be acknowledged:- Species Specificity: The models are derived from porcine tissues, which may not fully recapitulate human intestinal physiology, although pigs are widely regarded as relevant preclinical models (paper).
- Inhibitor Specificity: Endocytosis inhibitors can have off-target effects; thus, validation with multiple inhibitors and complementary genetic approaches is recommended (internal article).
- Throughput and Scalability: Organoid-based assays are more labor-intensive than traditional cell lines, which may limit their application in high-throughput screening workflows.
- Functional Readouts: While gene expression was assessed, broader functional assays (e.g., proliferation, barrier integrity, immune responses) would further substantiate physiological relevance.