Forskolin Swelling Assay

Forskolin activates adenylyl cyclase, which raises intracellular cyclic AMP. The increased cyclic AMP stimulates CFTR channels in the epithelial organoid, promoting chloride and bicarbonate secretion. Water then follows the secreted ions osmotically, producing measurable expansion. This sequence connects an upstream signaling change with a visible readout of epithelial transport function.

Swelling provides a functional phenotype rather than only showing whether CFTR is present. When stimulated channels support chloride and bicarbonate secretion, osmotic water movement expands the organoid; impaired CFTR activity produces less expansion. Imaging therefore translates channel performance into a quantitative morphological outcome that can reveal disease-associated dysfunction or treatment-related improvement.

The assay can show whether a therapy changes the functional response of epithelial organoids to cyclic AMP stimulation. Greater forskolin-induced expansion may indicate improved CFTR-mediated secretion, whereas limited swelling can indicate persistent dysfunction. Because the measurement reflects organoid behavior, it helps evaluate treatment effects in disease models and patient-derived samples.

The workflow begins with three-dimensional epithelial organoids, followed by forskolin stimulation to activate cyclic AMP signaling. Researchers then monitor expansion by imaging and quantify the resulting change in organoid size. Comparing swelling across samples or treatment conditions provides a functional assessment of CFTR activity without relying solely on molecular measurements.

Patient-derived organoids allow CFTR function to be examined in epithelial tissue originating from an individual with cystic fibrosis or another relevant condition. Their swelling responses can help characterize the functional impact of CFTR dysfunction and compare responses to modulating therapies. This creates a disease-modeling platform that links patient biology to measurable experimental outcomes.

In cystic fibrosis research, the assay helps connect defective CFTR activity with a measurable epithelial phenotype. It can support characterization of disease models, assessment of patient-derived organoids, and evaluation of CFTR-modulating compounds. By providing a visible functional endpoint, the method contributes to treatment selection and preclinical drug development.