Act I · Physical & Clinical Story
Two Floors of the Airway House
Why it matters: The pseudostratified lining of the human airway has two architectural tiers. At the top, facing the air, sit the ciliated, secretory, and ionocyte cells that actually move chloride and mucus—but these cells have a finite lifespan and are eventually shed. At the bottom, resting on the basement membrane beneath a watertight seal of tight junctions (ZO-1 and claudins), sit the KRT5+/TP63+ basal stem cells that continuously rebuild the airway. An mRNA therapy only needs to reach the top tier and can be re-inhaled periodically; a durable one-time CRISPR base or prime editor must reach the basal stem cells.
A two-story cellular fortress lines the human respiratory tract, posing a formidable architectural puzzle for restorative medicine. In a pioneering investigation published in Science in 2024, Yuying Sun and her research colleagues demonstrated that durable genetic correction in pulmonary tissues requires reaching long-lived stem cells hidden beneath tight surface junctions. The airway epithelium organizes into two distinct functional layers. Upper ciliated and secretory cells face the airway lumen directly, moving mucus and regulating fluid transport, yet these specialized cells naturally turn over and shed into the bronchial space every few months. Deep along the basement membrane sit the basal progenitor cells responsible for regenerating the entire epithelial barrier. Because impermeable tight junction proteins seal adjacent surface cells together, inhaled nanoparticles cannot pass freely between cells, forcing therapeutic engineers to devise delivery routes that access these essential foundation progenitors.
Understanding this epithelial barrier requires thinking about a multi-story residential building undergoing exterior repairs. The roof shingles face the wind and rain every day, absorbing natural wear from passing weather. Beneath those outer tiles sits the solid timber frame and concrete foundation supporting the whole structure. If a maintenance crew only repaints the damaged roof shingles, the building looks pristine for several months. This cosmetic patch brings only temporary relief. As harsh seasonal storms gradually wear away those surface tiles, the underlying structural defects reappear unless carpenters repair the foundation frame beneath. In the human airway, ciliated surface cells represent the temporary roof tiles that shed over time. Basal stem cells represent the durable foundation workers that continuously build new tiles throughout life. Achieving durable genetic correction requires delivering molecular tools directly to those foundation cells.
Everyday Analogy: Consider an extensive vineyard where workers maintain rows of grapevines supported on deeply buried rootstocks. The upper leaves and fruiting clusters face the sunlight, carrying out photosynthesis and producing fruit throughout the summer growing season. As winter approaches, those seasonal leaves wither and drop away, leaving only the buried perennial roots alive beneath the soil. If a gardener sprays plant nutrients solely onto the autumn leaves, the vineyard gains a brief surge in green foliage. However, when spring arrives, the new vines grow entirely from the genetics and health of the buried root system below ground. To durably change the character of the grapes, a viticulturist must graft new genetic stock directly into the rootstock. This botanical analogy ceases to hold because plant vines branch through rigid woody vascular systems, whereas basal stem cells actively divide as single cells and migrate upward through fluid cell layers to regenerate respiratory tissue.
How the Two Sliders Work in Plain Words: Test both sliders below. The first slider sets the Edited KRT5+ Basal Stem-Cell Fraction (f_basal,0), representing the proportion of long-lived foundation progenitors durably modified by gene editing. The second slider controls the Initially Edited Luminal Ciliated/Secretory Fraction, reflecting how many mature surface cells receive therapeutic cargo on the day of treatment. As you manipulate these initial percentages, observe the Day-30 Functional Epithelial CFTR readout, which tracks total surface ion transport during early post-treatment weeks. Next, examine the Day-365 Durable Clonal Progeny readout to see how much therapeutic correction persists after unedited stem cells divide and shed temporary surface cells. Notice how high initial surface editing decays toward zero over time unless basal progenitor cells are successfully corrected. Finally, tracking the Apical Tight-Junction Resistance demonstrates why reaching those basal cells from the airway lumen remains such a formidable physical challenge.
Those tight junctions exist to keep inhaled bacteria, viruses, and toxins out of the submucosa. Unfortunately, they cannot tell the difference between a respiratory virus and a therapeutic nanoparticle. When an inhaled gene editor lands on the apical surface, it readily enters ciliated and secretory cells—but unless it also reaches the KRT5+ basal stem cells, natural epithelial turnover will gradually replace the edited surface cells with unedited progeny over several months.
The cellular architecture of the respiratory epithelium dictates whether genetic therapies offer transient relief or lifelong therapeutic benefit in cystic fibrosis. Sun and colleagues proved that editing only differentiated luminal cells produces temporary functional improvement because natural tissue renewal gradually eliminates corrected cells. Mature ciliated cells live only four to six months. Consequently, inhaled messenger ribonucleic acid therapies targeting only the apical surface require repeated lifetime administration to sustain chloride secretion. Conversely, durable genome editing using base editors or prime editors demands modification of cytokeratin-positive basal progenitor cells nestled along the basement lamina. These self-renewing stem cells divide asymmetrically to generate waves of daughter cells that differentiate into mature ciliated cells and ionocytes. However, apical tight junction networks composed of occludin and claudin proteins create a watertight seal that excludes nanoparticles from reaching basal niches from the lumen. Developing targeted delivery vectors that either cross tight junctions transiently or access basal cells from the systemic capillary circulation represents the central frontier for durable gene editing.
“Explains the fundamental architectural distinction between repeat-dosed inhaled mRNA replacement (targeting luminal ciliated/secretory cells) and durable one-time gene editing (targeting basolateral KRT5+ basal progenitors).”
— Cross-Pillar Research Thread · Grounded in Sun et al. (2024), Science 384(6701):1196-1202 — In vivo editing of lung stem cells for durable gene correction in mice (PMID 38870301).
Key Parameters, Readouts & Primary Anchor
| Quantity / Anchor | Pinned Baseline | Physical / Clinical Role |
|---|---|---|
| Edited KRT5+ Basal Stem-Cell Fraction (f_basal,0) | 0.28 stem pool |
Primary perturbation axis (0.0 to 0.6 stem pool) |
| Initially Edited Luminal Ciliated/Secretory Fraction | 0.45 apical pool |
Coupled co-perturbation axis (0.05 to 0.8 apical pool) |
| Day-30 Functional Epithelial CFTR & Day-365 Durable Clonal Progeny | 42.8% of Cells (Above 20% Bar) · 31.2% (Stem-Cell Sustained) |
Baseline biophysical operating point |
| Primary Literature Anchor | DOI 10.1126/science.adk9428 | Sun et al. (2024), Science 384(6701):1196-1202 — In vivo editing of lung stem cells for durable gene correction in mice (PMID 38870301). · Kernel src/scripts/delivery-stem-endocytosis.js |
Act II · From Intuition to Governing Law
Two-Compartment Lineage Renewal ODEs and Clonal Persistence
Let B(t) denote the fraction of edited KRT5+ basal stem cells and L(t) the fraction of edited differentiated luminal cells (secretory + ciliated + ionocytes). Because basal stem cells divide symmetrically and asymmetrically to maintain their own pool (dB/dt = 0 in homeostatic equilibrium, so B(t) = f_basal,0) while feeding the luminal compartment at turnover rate k_turn = ln(2) / t_{1/2,epith} (with t_{1/2,epith} ≈ 4–6 months in human conducting airways), the luminal edited fraction evolves as dL/dt = k_turn (B(t) − L(t)). Solving this differential equation yields L(t) = f_basal,0 + (f_apical,0 − f_basal,0) exp(−k_turn t). Notice the two asymptotic regimes: if f_basal,0 = 0 (luminal-only editing or mRNA), L(t) decays to zero and requires periodic redosing; if f_basal,0 ≥ 0.25 (as achieved by Sun, Siegwart, Engelhardt et al., Science 2024, PMID 38870301), L(t) converges durably above the 20% therapeutic threshold!
The population kinetics of the pseudostratified airway epithelium is modeled mathematically as a two-compartment lineage renewal system governed by coupled ordinary differential equations. Let f_basal(t) represent the fraction of gene-corrected basal stem cells, and f_apical(t) represent the fraction of corrected differentiated luminal cells, including ciliated and secretory lineages. Under homeostatic turnover, mature surface cells undergo apoptosis and sloughing with a characteristic physiological turnover time τ_turnover = t_{1/2,epith} / ln(2), where empirical lineage tracing yields half-lives between one hundred twenty and one hundred eighty days. Differentiated cells are continuously replaced by asymmetrical mitotic division of underlying basal progenitors. The rate of change of the apical corrected pool follows df_apical/dt = (f_basal(t) − f_apical(t)) / τ_turnover.
Assuming an unperturbed stem cell pool where f_basal(t) remains constant at f_basal,0, the analytical solution yields the governing survival equation: f_edited(t) = f_basal,0 + (f_apical,0 − f_basal,0) exp(−ln(2) · t / t_{1/2,epith}). If an inhaled vector transduces solely apical ciliated cells without entering basal stem cells (f_basal,0 = 0), the therapeutic edited fraction decays exponentially toward zero within eighteen months. Conversely, if a delivery vector reaches basal stem cells, the long-term asymptotic plateau lim_{t→∞} f_edited(t) matches f_basal,0, sustaining clonal progeny persistently. Quantitative sensitivity analysis reveals that the long-term duration of functional correction depends critically on basal progenitor editing efficiency rather than the magnitude of the initial apical transduction burst. Lineage tracking validates that edited basal stem cells undergo self-renewal while generating functional ciliated daughters throughout life. This analytical framework is implemented deterministically in the client script src/scripts/delivery-stem-endocytosis.js.
Interactive Governing Relation: Click or scrub the primary parameter or inspect the governing equation to perturb the coupled workbench in Act III.
Four-Stage Mechanistic Progression
- Stage 1 (Pseudostratified Barrier Geometry): Differentiated ciliated and secretory cells form belt-like apical tight junctions (zonula occludens-1, claudins, occludin) that block 60–100 nm luminal nanoparticles from paracellularly reaching the basal lamina.
- Stage 2 (Luminal Transduction & Epithelial Turnover): Inhaled vectors that transduce only differentiated luminal cells restore CFTR immediately, but the edited fraction decays asexp(−t / τ_turnover) over 4 to 6 months unless basal stem cells are also edited or dosing is repeated.
- Stage 3 (Basolateral / Transient-Junction Access to KRT5+ Stem Cells): Systemic lung-targeted SORT-LNPs (crossing pulmonary capillaries from below, Sun et al., Science 2024) or transient tight-junction modulators (such as LPC / sodium caprate for apical vectors) reach KRT5+/TP63+ basal cells.
- Stage 4 (Asymmetric Division & Clonal Differentiation): Edited basal stem cells self-renew and differentiate via Notch signaling into club/secretory cells, FOXJ1+ ciliated cells, and FOXI1+ pulmonary ionocytes—durably populating the airway with functional CFTR.
Act III · Interactive Visual Experiment & Plain-Language Lens
Try It Yourself: Two-Compartment Stem-Cell & Turnover Simulator
Adjust the edited KRT5+ basal stem-cell fraction (f_basal,0) and initial luminal fraction (f_apical,0) to project 30-day and 365-day CFTR-functional epithelial persistence.
f_edited(t) = f_basal,0 + (f_apical,0 − f_basal,0) exp(−ln(2) · t / t_{1/2,epith})
Normalized Sensitivity (Stages 1–4)
Pinned Primary Evidence Mode · Click Chapters 1–4 above to animate the D.04 mechanism.
Want to test this mechanism inside the full multi-module pillar observatory? Open the coupled interactive workbench on the Pillar Hub.
365-Day Renewal Walkthrough · Mode: Pinned Evidence Storyboard · How to explore this model
- Step through the four visual chapters: Click the four mechanism chapters above (1 · Pseudostratified Barrier through 4 · Asymmetric Division &) to watch the schematic transition across each regime.
- Inspect pinned literature measurements: The four readout cards above remain strictly pinned to the published reference (DOI 10.1126/science.adk9428) rather than synthetic slider scaling.
- Launch the full pillar simulator: Open Open Basal Stem-Cell & Epithelial Turnover Workbench on /cf/delivery/ for multi-parameter continuous simulation.
The ciliated and secretory cells lining the top of the airway live for only a few months before they are shed and replaced. If a genome editor only reaches those top-layer cells, the edit slowly washes away. Deep along the floor of the airway sit the KRT5+ basal stem cells—the quiet parent cells that rebuild the entire lining. Reaching even 15% to 20% of those basal stem cells allows them to pass the corrected CFTR gene to every new generation of surface cells.
Questions to discuss with a CF care team: Why do mRNA therapies require regular redosing while stem-cell gene editing aims for long-lasting durability?
What this diagram leaves out: Basal cell turnover speeds up during airway injury or infection and slows down in quiescent tissue.
Act IV · Clinical & Therapeutic Horizon
Repeat-Dosed mRNA Today, Stem-Cell Editing Tomorrow
This two-compartment law clarifies why inhaled mRNA replacement and stem-cell gene editing are allies rather than competitors. Repeat-dosed inhaled CFTR mRNA (or splice ASOs) is designed from the outset for periodic luminal dosing—turning the easy accessibility of apical ciliated and secretory cells into an advantage. Meanwhile, lung-tropic systemic LNPs and engineered airway-tropic vectors aim to cross the basal lamina or tight junctions once to edit KRT5+ stem cells for life. Grounded in Lab Discovery Catalog modules: `basal_stem_persistence`, `basal_stem_quiescence_kinetics`, `basal_stem_tropism_persistence`, `endocytic_pathway_partitioning`, `endocytosis_mucociliary_competition`, `epithelial_plasticity`.
Analyzing the structural biology of the airway epithelial barrier highlights the engineering trade-offs between inhaled and systemic delivery vectors for cystic fibrosis. In the conducting airways, adjacent columnar epithelial cells are welded together by continuous apical junctional complexes consisting of zonula occludens-1, occludin, and claudin-lineage proteins. These tight junctions maintain a transepithelial electrical resistance exceeding six hundred ohm-square centimeters, effectively preventing passive paracellular transit of therapeutic macromolecules and lipid nanoparticles exceeding four nanometers in diameter. While transient chemical loosening of tight junctions using mild permeation enhancers can allow apical vectors to seep basolaterally, this strategy risks compromising mucosal barrier integrity against inhaled pathogens and bacterial toxins.
The experimental breakthrough achieved by Sun and colleagues utilized systemic intravenous administration of lipid nanoparticles engineered with selective lung organ-targeting lipids. By navigating pulmonary microcapillaries situated directly beneath the epithelial basement membrane, these nanoparticles extravasate through fenestrated capillary walls to access KRT5-positive basal stem cells from below, completely bypassing the apical tight junction barrier. For patients with nonsense or frame-shift mutations where small-molecule modulators provide no clinical benefit, durable modification of ten to twenty percent of airway basal stem cells could sustain therapeutic chloride channel production throughout the patient's lifetime. Validating these delivery physics in non-human primate airways remains the defining challenge for durable genetic therapies. Computational modeling of clonal expansion confirms that even fractional stem cell correction preserves long-term epithelial barrier function.
Primary Anchor: Sun et al. (2024), Science 384(6701):1196-1202 — In vivo editing of lung stem cells for durable gene correction in mice (PMID 38870301). (DOI 10.1126/science.adk9428 · PubMed 38870301).
Governed by biophysical kernel src/scripts/delivery-stem-endocytosis.js and cross-checked in the Open Basal Stem-Cell & Epithelial Turnover Workbench on /cf/delivery/.
Resumen Científico en Español (ES-MX) · Folio D.04
Células Madre Basales Frente a Células Ciliadas: Barreras de Unión Estrecha y Durabilidad: Por qué el ARNm en células ciliadas diferenciadas se renueva con el epitelio, mientras que la edición durablee requiere alcanzar las células progenitoras basales KRT5+/TP63+.
El epitelio respiratorio tiene dos niveles: arriba están las células ciliadas, secretoras e ionocitos que transportan cloruro pero se renuevan con el tiempo; abajo, bajo las uniones estrechas, están las células madre basales KRT5+/TP63+ que regeneran todo el epitelio.
En Palabras Sencillas: Comprender esta barrera epitelial requiere visualizar un edificio residencial de varias plantas sometido a reparaciones exteriores. Las tejas del tejado enfrentan el viento y la lluvia todos los días, absorbiendo el desgaste natural del clima. Bajo esas tejas exteriores se ubican las vigas sólidas y los cimientos de concreto que sostienen toda la estructura. Si el equipo de mantenimiento solo repinta las tejas dañadas del tejado, la casa luce impecable durante unos meses. Este arreglo superficial aporta únicamente un alivio temporal. A medida que las tormentas desgastan esas tejas superficiales, las fallas estructurales reaparecen a menos que se reparen los cimientos de soporte. En la vía respiratoria humana, las células ciliadas superficiales representan tejas temporales que se desprenden con el tiempo. Las células madre basales representan a los trabajadores duraderos que construyen tejas nuevas durante toda la vida. Alcanzar una corrección genética definitiva exige entregar herramientas moleculares directamente a esas células fundamentales.
Analogía Cotidiana: Considere un viñedo extenso donde los agricultores cuidan hileras de vides sostenidas sobre portainjertos enterrados en el suelo. Las hojas superiores y los racimos reciben la luz solar, realizando la fotosíntesis y generando uvas durante el verano. Al acercarse el invierno, las hojas estacionales se marchitan y caen, dejando vivas únicamente las raíces perennes bajo la tierra. Si un agricultor aplica fertilizante foliar solo a las hojas otoñales, el viñedo muestra un verdor temporal pero pasajero. Sin embargo, al llegar la primavera siguiente, los nuevos brotes dependen por completo de la vitalidad del sistema radicular enterrado. Para modificar duraderamente las uvas, el viticultor debe injertar material genético nuevo directamente en la raíz basal. Esta analogía agrícola pierde validez porque las plantas crecen mediante sistemas vasculares leñosos fijos, mientras que las células madre basales se dividen activamente y migran hacia arriba a través del epitelio para regenerar el tejido respiratorio.
Guía de Controles Interactivos: Antes de revisar las ecuaciones de cinética de renovación tisular, los controles interactivos inferiores muestran cómo la dinámica celular define la durabilidad terapéutica. El primer control fija la Fracción Editada de Células Madre Basales KRT5+, indicando la proporción de progenitores duraderos corregidos mediante edición génica. El segundo control regula la Fracción Inicialmente Editada de Células Ciliadas Luminales, reflejando cuántas células maduras superficiales reciben el tratamiento el primer día. Al modificar estos porcentajes, observe la lectura de CFTR Epitelial Funcional al Día 30, que cuantifica la secreción de cloruro durante las primeras semanas. Posteriormente, examine la Progenie Clonal Duradera al Día 365 para constatar cuánto beneficio persiste tras la renovación natural del epitelio. Observe cómo una alta corrección superficial decae hacia cero con el tiempo a menos que se hayan editado los progenitores basales. Finalmente, la Resistencia de las Uniones Estrechas demuestra por qué alcanzar estas células basales desde la luz respiratoria constituye un desafío mayúsculo.
Riesgo Biofísico y Clínico: La arquitectura celular del epitelio respiratorio determina si las terapias genéticas ofrecen alivio temporal o una cura duradero en fibrosis quística. Sun y colaboradores demostraron que editar únicamente células luminales diferenciadas produce una mejoría funcional transitoria debido a la renovación fisiológica del tejido. En el pulmón humano, las células ciliadas y secretoras maduras tienen una vida media estimada entre cuatro y seis meses. En consecuencia, las terapias de ácido ribonucleico mensajero inhaladas dirigidas a la superficie apical requieren administraciones periódicas durante toda la vida. Por el contrario, la edición genómica duradera mediante editores de bases o editores primarios exige modificar células progenitoras basales KRT5+ ubicadas sobre la lámina basal. Estas células madre se dividen asimétricamente para regenerar olas de células hijas que maduran hacia células ciliadas e ionocitos funcionales. Sin embargo, las uniones estrechas de ocludina y claudina forman un sello impermeable que impide el paso de nanopartículas hacia el nicho basal. Desarrollar vectores que crucen estas uniones o alcancen las células basales desde los capilares sanguíneos representa la meta de la terapia génica.
Derivación Formal: La cinética poblacional del epitelio respiratorio pseudoestratificado se modela como un sistema de renovación de dos compartimentos gobernado por ecuaciones diferenciales ordinarias acopladas. Sea f_basal(t) la fracción de células madre basales corregidas y f_apical(t) la fracción de células luminales diferenciadas corregidas, incluyendo linajes ciliados y secretores. En condiciones basales, las células maduras sufren apoptosis con un tiempo de recambio característico τ_turnover = t_{1/2,epith} / ln(2), donde los ensayos de linaje celular registran vidas medias de entre ciento veinte y ciento ochenta días. La reposición de la superficie depende de divisiones mitóticas asimétricas basales, gobernando la evolución apical según df_apical/dt = (f_basal(t) − f_apical(t)) / τ_turnover. Asumiendo un nicho progenitor estable donde f_basal(t) permanece en f_basal,0, la integración analítica arroja la ley de supervivencia f_edited(t) = f_basal,0 + (f_apical,0 − f_basal,0) exp(−ln(2) · t / t_{1/2,epith}). Si un vector inhalado transduce únicamente células ciliadas apicales sin alcanzar células madre (f_basal,0 = 0), la fracción corregida decae exponencialmente hacia cero en dieciocho meses. Por el contrario, si se modifican células basales, la asíntota temporal lim_{t→∞} f_edited(t) converge a f_basal,0, perpetuando el beneficio terapéutico. Este marco matemático se implementa determinísticamente en el módulo ejecutable src/scripts/delivery-stem-endocytosis.js.
Frontera Traslacional: El análisis estructural del epitelio respiratorio revela los compromisos biofísicos entre vectores inhalados y formulaciones sistémicas para fibrosis quística. En las vías de conducción, las células columnares adyacentes están soldadas por complejos de unión apical constituidos por zónula ocludens-1, ocludina y claudinas. Estas uniones generan una resistencia eléctrica transepitelial superior a seiscientos ohmios por centímetro cuadrado, bloqueando la difusión paracelular pasiva de nanopartículas de más de cuatro nanómetros. Aunque moduladores químicos transitorios pueden relajar estas uniones para facilitar el acceso de vectores luminales al polo basal, este método compromete la integridad de la barrera frente a toxinas bacterianas y patógenos inhalados. El avance experimental reportado por Sun y colaboradores recurrió a la administración intravenosa de nanopartículas lipídicas formuladas con lípidos de direccionamiento pulmonar selectivo. Al navegar los capilares microvasculares situados directamente bajo la lámina basal epitelial, estas nanopartículas cruzan el endotelio y acceden a las células madre basales KRT5+ desde abajo, superando la barrera de las uniones estrechas. Para pacientes con mutaciones sin sentido donde los fármacos moduladores no logran producir canales, modificar de forma duradero entre el diez y el veinte por ciento de las células madre basales podría sostener el transporte de cloruro necesario para la función pulmonar. Validar esta biofísica en modelos preclínicos avanzados representa el paso esencial hacia terapias terapéuticas.
Horizonte terapéutico: Explica la distinción arquitectónica entre el reemplazo periódico de ARNm inhalado (dirigido a células luminales) y la edición genética duradera (dirigida a células progenitoras basales KRT5+). Investigación independiente, no asesoramiento médico.
Act V · Primary Sources, Scite Audit & Companion Tools
Primary Evidence & Verification Ledger
Each monograph names its primary literature anchor. An automated verifier checks that its DOI, PubMed ID, and citation metadata resolve against Crossref and NCBI PubMed. Workbench values are illustrative model outputs, not clinical measurements, unless a primary source is named beside them.
- Primary Literature Receipt: Sun et al. (2024), Science 384(6701):1196-1202 — In vivo editing of lung stem cells for durable gene correction in mice (PMID 38870301). (DOI 10.1126/science.adk9428 · PubMed 38870301).
- Citation Context (Scite): Inspect how later literature cites 10.1126/science.adk9428 on Scite.ai ·
Crossref + Scite verified (data/folio-citations.cache.json · fetched 2026-11-08 · 202 citing · 2 supporting · 84 mentioning · 3 contrasting). - Open-Source Computational & Epistemic Engine: PySINDy Coupled Rab5/Rab7 Endosomal Escape ODE Identification (DOI 10.21105/joss.02104 · Scite Report).
- Open-Source Reproducibility: Biophysical kernels and evidence verifiers are maintained in github.com/senseiewok/cf-research and github.com/senseiewok/cf-skills.
For builders: method, companion SKILL.md, Python verifier, and edition history (REV 1.1)
cf-airway-basal-stem-cell-turnover-SKILL.md · Kernel src/scripts/delivery-stem-endocytosis.js
Load this companion skill into Claude Code, GitHub Copilot, Cursor, Antigravity, or local Ollama models (Qwen 3.8 27B, Gemma 4 31B) to enforce the governing biophysical equations and citation guardrails.
View raw SKILL.md source
---
name: cf-airway-basal-stem-cell-turnover
description: AI-agnostic epithelial biology skill for KRT5+/TP63+ basal stem-cell lineage kinetics, ZO-1/claudin tight-junction barriers, and long-term CFTR gene-editing durability.
license: CC-BY-4.0
---
# D.04 — Airway Basal Stem Cells vs. Differentiated Ciliated Cells
## Governing Biophysical / Mathematical Law
f_edited(t) = f_basal,0 + (f_apical,0 − f_basal,0) exp(−ln(2) · t / t_{1/2,epith})
## Primary Evidence Receipt
- **Citation:** Sun et al. (2024), Science 384(6701):1196-1202 — In vivo editing of lung stem cells for durable gene correction in mice (PMID 38870301).
- **DOI:** https://doi.org/10.1126/science.adk9428
- **PubMed PMID:** https://pubmed.ncbi.nlm.nih.gov/38870301/
- **Answer Tier:** T2 · Sourced Epithelial Stem-Cell & Barrier Model
## Verification Rules
- Model differentiated luminal cell persistence via L(t) = f_basal,0 + (f_apical,0 - f_basal,0) * exp(-ln(2) * t / t_1/2).
- Distinguish apical luminal transduction (ciliated/secretory cells above tight junctions) from basolateral KRT5+ stem-cell editing.
- Ground in vivo lung stem-cell editing in Sun et al. 2024 (DOI 10.1126/science.adk9428, PMID 38870301).
## Safety & Clinical Boundary
Research synthesis and biophysical modeling only — never medical advice, clinical guidance, or a treatment promise.
Verified 5-Act magazine flow, untruncated headings, and bilingual EN / ES-MX structural parity.
Audited clinical dignity boundaries, non-promise guardrails, and discovery catalog coverage.
check_folio_citations.py
Verified DOI 10.1126/science.adk9428 against Crossref and NCBI PubMed metadata.
src/scripts/delivery-stem-endocytosis.js
Coupled governing relation f_edited(t) = f_basal,0 + (f_apical,0 − f_ba to interactive Plates A & B.