Engineered MSC‑derived exosomes loaded with TERT mRNA and senolytic siRNA will reset telomere‑based informational entropy, thereby reducing senescence burden, lowering transcriptional noise, and reversing epigenetic age in neurodegenerative disease models.

Mechanistic Rationale

Telomeres function as a quantum clock that quantifies accumulated informational entropy rather than merely counting divisions【4†L1-L3】. In aging and neurodegeneration, rising entropy manifests as telomere shortening, increased senescent cell burden, and heightened single‑cell transcriptional heterogeneity. Native MSC‑exosomes deliver anti‑inflammatory miRNAs (e.g., miR‑148a, miR‑532-5p, miR-378) that transiently dampen inflammation but do not alter the entropic signal measured by telomeres【4†L10-L13】. By contrast, exosomes engineered to carry TERT mRNA provide a catalytic source of telomerase that can elongate telomeres in recipient cells, directly decreasing the entropy readout. TERT also possesses non‑canonical actions that improve mitochondrial redox balance and chromatin compaction, further limiting noise generation【5†L1-L4】. Co‑loading senolytic siRNA targeting p16^INK4a^ removes existing senescent cells, preventing them from re‑introducing entropy via the SASP. Together, this cargo resets the telomeric clock, restores transcriptional fidelity, and measurable outcomes can be tracked with DNAmAge clocks and single‑cell RNA‑seq entropy metrics.

Experimental Design

1. Exosome production – Isolate MSCs from Wharton’s jelly, load via Exo‑Fect transfection with TERT mRNA (≈40 % efficiency) and siRNA‑p16 (≈35 % efficiency)【5†L5-L8】【6†L2-L4】. Validate cargo by qPCR and Western blot.
2. In vivo model – Use aged SOD1^G93A^ mice (ALS model) exhibiting telomere attrition in spinal cord neurons and glia【1†L1-L3】. Randomize to three groups: (a) engineered TERT/siRNA exosomes (IV, 2 × 10^9 particles weekly), (b) control MSC‑exosomes (same dose, empty cargo), (c) saline.
3. Readouts (at 4 weeks)
   • Telomere length (qFISH) in NeuN^+^ and Iba1^+^ cells.
   • Senescent burden (p16^INK4a^ immunostaining, SA‑β‑gal activity).
   • DNAmAge (epigenetic clock) from sorted neuronal nuclei.
   • Transcriptional heterogeneity (Shannon entropy from scRNA‑seq of spinal cord).
   • Functional outcome (rotarod performance, grip strength).
   • Safety ( cytokine panel, histology for off‑target effects).
4. Statistical plan – Power analysis targeting 30 % telomere length increase (α=0.05, power=0.8) yields n=10 per group.

Predicted Outcomes

• Engineered exosomes will show a significant increase in telomere length (>25 % vs control) concurrent with reduced p16^+^ senescent cells (<50 % of control).
• DNAmAge will demonstrate a reversal of age acceleration by ≥1.5 epigenetic years.
• Single‑cell transcriptional entropy will decrease, indicating lower informational noise.
• Motor performance will improve (≥20 % longer rotarod latency) and correlate with telomere restoration.
• Control exosomes will produce only transient anti‑inflammatory effects without changes in telomere length or epigenetic age.

Falsifiability

If engineered exosomes fail to elongate telomeres, reduce senescence, or alter DNAmAge and transcriptional entropy despite confirmed delivery and expression of TERT/siRNA, the hypothesis that telomere‑based informational entropy drives neurodegenerative pathology and can be reset by exosomal telomerase activity will be falsified. Conversely, positive results would support the model that precision paracrine signaling targeting the telomeric clock translates transient symptom relief into durable biological rejuvenation.