Controllable Molecular Delivery from Maternal Cells: A Mechanistic Hypothesis for Selective Chromosome Dosage Compensation in Trisomy 21

Background. Expression imbalance in trisomy 21 involves multiple genes and cell types. Establishing XIST expression on a selected chromosome 21 has enabled chromosome-wide silencing and improved some functional outcomes in cultured cells and differentiation models. Extending this capability to patient cells without prior engineering remains constrained by homolog recognition, intact cargo delivery, nuclear localization, and persistence of action. Maternal cells can be investigated as a production platform, but cannot be assumed to possess an innate ability to recognize or repair an additional chromosome in their offspring.Hypothesis. Following identification of a target haplotype and assessment of the functional suitability of the two homologs to be retained, a controllably delivered engineered molecular system might establish single-homolog, chromosome-wide repression in the patient’s own trisomy 21 cells and bring prespecified cellular functions closer to a matched disomic reference. XIST-mediated cis silencing is the principal mechanism considered; physical chromosome elimination is a separate comparative branch. Maternal cell–derived extracellular vesicles are a candidate delivery vehicle, and mother–offspring matching is a platform subhypothesis. IFNAR1 and IFNAR2 modulation serves only to validate local tool activity and function, not as a substitute for chromosome-wide dosage compensation.Discriminating tests. Haplotype recognition, cargo release and nuclear availability, single-homolog action, chromosome-wide expression changes, protection of disomic cells, and functional benefit must be tested separately. Direct-delivery benchmarks, unloaded products, nontargeting cargo, cross-family comparisons, and single-cell analyses distinguish effector activity, delivery performance, source advantages, and cell-population selection. Stopping production, stopping XIST transcription, and reversing established silencing are distinct endpoints.Significance. This framework focuses on chromosome dosage compensation in the patient’s own cells and generates conditional predictions for steps that have not yet been connected experimentally. It reports no original experimental data, presents no complete therapeutic cargo system, and does not claim novelty solely from combining existing modules.