Lysosomal Rejuvenation Atlas

Reversing Lysosome Dysfunction to Restore Youthful Hematopoietic Stem Cells
Arif, Qiu et al. · Cell Stem Cell 32(12):1904–1922 · 2025 · Ghaffari Lab, Mt. Sinai

The Lysosome–HSC Aging Axis

Hematopoietic stem cells sustain lifelong blood production, but aging cripples them — driving clonal hematopoiesis, myeloid skewing, and immune decline. A landmark 2025 study reveals that lysosomal dysfunction is not a passive bystander but an active driver of HSC aging — and reversing it restores youthful function.

8×
Repopulation Boost
Old HSCs after v-ATPase inhibition
↑ pH
Hyperacidic
Aged lysosomes too acidic
mtDNA
Leakage → cGAS
Damaged lysosomes fail to clear
Restored
Self-Renewal
Epigenetic + metabolic homeostasis
Young HSC Balanced lysosomes AGING H⁺H⁺ H⁺ mtDNA Aged HSC Hyperacidic, damaged v-ATPase inh. Bafilomycin A1 ✨ Rejuvenated HSC 8× repopulation capacity ↓ Inflammation ↓ cGAS-STING ↑ Self-renewal
Figure 1. The lysosomal rejuvenation paradigm: v-ATPase inhibition converts aged, dysfunctional HSCs into functionally youthful cells with 8-fold improved repopulation capacity.
🔬 Key Discovery

Lysosomes in aged HSCs are not merely worn out — they are hyperactivated. Aberrant vacuolar ATPase (v-ATPase) activity drives excessive acidification, leading to lysosomal membrane damage, impaired mitochondrial DNA clearance, and chronic cGAS-STING inflammatory signaling. Pharmacological suppression of hyperactivated lysosomes with Bafilomycin A1 ex vivo restores metabolic and epigenetic homeostasis, boosting in vivo repopulation by over 8-fold.

🧬 Clinical Implications

This work establishes lysosomes as a druggable target for HSC rejuvenation. Potential applications include: improving bone marrow transplant outcomes in elderly patients, reducing clonal hematopoiesis of indeterminate potential (CHIP), mitigating age-related immune decline (immunosenescence), and developing ex vivo HSC conditioning protocols for regenerative medicine.

HSC Repopulation Capacity by Age & Treatment
Lysosomal Dysfunction Markers in Aged HSCs

Lysosome Biology in Stem Cells

Far from simple recycling bins, lysosomes are dynamic signaling hubs that control stem cell fate, metabolism, and quiescence. In HSCs, lysosomal activity is tightly calibrated — a balance that breaks down catastrophically with age.

V₀V₁ H⁺→ LAMP1 LAMP2A CatB CatD CatL pH 4.5–5.0 Acidic lumen Lysosome Structure Core Functions in HSCs 🔄 Macroautophagy Bulk degradation of damaged organelles via autophagosomes 🎯 Chaperone-Mediated Autophagy (CMA) Selective protein import via LAMP2A + KFERQ motif → quality control ⚡ mTORC1 Signaling Hub Nutrient sensing from lysosomal surface → growth/quiescence decision 🧬 Mitochondrial DNA Processing Degradation of cytoplasmic mtDNA fragments → prevents cGAS activation 💤 Quiescence Maintenance Low lysosomal activity (MMP-low) = dormant, long-term repopulating HSC
Figure 2. Lysosome structure and core functions in HSC homeostasis. v-ATPase proton pump maintains luminal pH; LAMP proteins mediate CMA; lysosomal surface hosts mTORC1 signaling.
MMP Heterogeneity

HSCs are heterogeneous in their mitochondrial membrane potential (MMP). MMP-low HSCs represent the most primitive, quiescent, long-term repopulating fraction. These cells have characteristically low lysosomal activity — "sluggish lysosomes" — which paradoxically maintains their stemness by limiting mTOR signaling and preserving metabolic dormancy.

MMP-low = Dormant
MMP-high = Activated
TFEB: Master Lysosomal Regulator

Transcription Factor EB (TFEB) is the master regulator of lysosomal biogenesis. When mTORC1 is active on the lysosomal surface, it phosphorylates TFEB, keeping it cytoplasmic and inactive. Lysosomal stress or starvation inactivates mTORC1, allowing TFEB nuclear translocation → upregulation of 300+ lysosomal/autophagy genes. In aged HSCs, this regulatory circuit is dysregulated.

TFEB → Lysosomal Genes
mTORC1 ⊣ TFEB
Lysosomal Gene Expression: Young vs Aged HSCs

The Lysosomal Aging Cascade

How do healthy lysosomes become agents of destruction? The cascade unfolds in six stages, from initial hyperactivation to systemic immune decline. Each stage amplifies the next, creating a vicious cycle that accelerates HSC aging.

① v-ATPase Hyperactivation • Increased V₀V₁ complex assembly • Excessive proton pumping • pH drops below normal range → Lysosomes become hyperacidic ② Lysosomal Membrane Damage • Membrane permeabilization (LMP) • Cathepsin leakage to cytoplasm • LAMP protein degradation → Lysosomes depleted & damaged ③ Impaired mtDNA Clearance • Mitophagy completion fails • Cytoplasmic mtDNA accumulates • Mitochondrial dysfunction amplifies → mtDNA becomes danger signal ④ cGAS-STING Activation • cGAS detects cytoplasmic mtDNA • 2'3'-cGAMP → STING activation • TBK1/IRF3 phosphorylation → Type I interferon induction ⑤ Chronic Inflammation • ISG upregulation (IFN-stimulated) • NF-κB inflammatory programs • Epigenetic remodeling (H3K27me3↓) → HSC exhaustion & myeloid bias ⑥ HSC Functional Decline • ↓ Repopulation capacity (>8×) • ↓ Self-renewal, ↑ myeloid skewing • Clonal hematopoiesis (CHIP) → Immunosenescence, malignancy risk ↻ Vicious cycle: inflammation → further lysosomal damage 🎯 Intervention Point: v-ATPase Inhibition Breaks cascade at Stage ① → prevents downstream damage
Figure 3. The six-stage lysosomal aging cascade in HSCs. v-ATPase hyperactivation initiates a self-amplifying destructive cycle. Pharmacological intervention at Stage ① breaks the entire chain.
Cascade Amplification: Fold-Change by Stage
Inflammatory Cytokine Profile: Young vs Aged HSC

v-ATPase Inhibition: The Rejuvenation Switch

Bafilomycin A1, a specific v-ATPase inhibitor, administered ex vivo to aged HSCs for just 16 hours reverses decades of accumulated dysfunction. The treatment normalizes lysosomal pH, restores membrane integrity, silences cGAS-STING inflammation, and recovers epigenetic marks — producing functionally young stem cells.

16h
Treatment Duration
Ex vivo Bafilomycin A1
8.3×
Repopulation Boost
In vivo transplant assay
↓ 73%
ISG Expression
Interferon-stimulated genes
BafA1 v-ATPase inhibitor ⊗ INHIBIT v-ATPase V₀ subunit c Proton pump blocked pH Normalization Hyperacidic → normal range pH 3.8 → 4.5–5.0 mTOR Suppression Reduced lysosomal mTORC1 → TFEB nuclear entry cGAS-STING ↓ Improved mtDNA clearance → ISG/IFN programs silenced Epigenetic Reset H3K27me3 marks restored → Youthful chromatin state Youthful HSC 8× repopulation ✨
Figure 4. Mechanism of v-ATPase inhibition by Bafilomycin A1. Blocking the V₀ subunit c proton channel normalizes pH, suppresses mTOR, silences cGAS-STING, and restores epigenetic marks — yielding functionally young HSCs.
Transplant Repopulation: Treated vs Untreated Old HSCs
Gene Expression Changes After v-ATPase Inhibition
Key Experimental Details
ParameterValueSignificance
DrugBafilomycin A1 (BafA1)Specific macrolide v-ATPase inhibitor, binds V₀ subunit c
Concentration10 nMSub-cytotoxic dose, lysosome-selective
Duration16 hours ex vivoSingle treatment window, no continuous dosing
ModelC57BL/6 mice, 22–24 monthsPhysiologically aged, not genetically accelerated
AssayCompetitive transplantGold standard for HSC function assessment
Repopulation8.3× increaseOld treated ≈ young untreated levels
Self-renewalSignificantly improvedSecondary transplant capacity restored
LineageBalanced output restoredMyeloid bias corrected toward balanced myeloid/lymphoid

Signaling Pathway Network

An interactive map of the interconnected pathways linking lysosomal dysfunction to HSC aging. Click on any node to explore its role, upstream regulators, and downstream effects.

v-ATPase V₀V₁ Lysosomal pH LMP Membrane Cathepsins Cytosolic mtDNA mTORC1 on lysosome Autophagy cGAS STING TBK1 IRF3 ISGs NF-κB TFEB Lysosomal Biogenesis LAMP2A CMA HSC Exhaustion SASP Apoptosis Activation Inhibition Lysosomal Metabolic Inflammatory Epigenetic
Figure 5. Signaling pathway network linking lysosomal dysfunction to HSC aging. Click any node to view details. Dashed lines = inhibitory relationships.

Rejuvenation Strategy Arena

Multiple approaches can rejuvenate aged HSCs by targeting different nodes of the lysosomal–inflammatory cascade. Here we compare 6 strategies by mechanism, evidence strength, clinical feasibility, and efficacy.

Strategy Target Mechanism Efficacy Evidence Clinical Stage
v-ATPase Inhibition
BafA1		 v-ATPase V₀ subunit Block proton pump → normalize lysosomal pH → restore integrity 8.3× repopulation Cell Stem Cell 2025 Preclinical
CMA Activation
LAMP2A↑		 LAMP2A receptor Enhance selective protein degradation → quality control → FAO Restored function Nature 2021 (Dong) Preclinical
pH Treatment
pH 6.9		 Extracellular pH Mild acidic culture → unknown mechanism → improves engraftment 3× repopulation Aging Cell 2024 Preclinical
Rapamycin
mTOR inh.		 mTORC1 Inhibit mTOR → activate TFEB → boost autophagy/lysosomal biogenesis 2–5× improvement Multiple studies Phase 3 (PROSPR)
Dietary Restriction
Caloric		 AMPK/mTOR axis Nutrient deprivation → AMPK↑ → mTOR↓ → lysosomal gene remodeling Partial rescue Biogerontology 2025 Epidemiological
STING Inhibitors
H-151		 STING palmitoylation Block downstream inflammation without fixing lysosomal root cause Indirect rescue Multiple reviews Preclinical
Strategy Comparison Radar
Evidence Strength by Strategy
Why v-ATPase Inhibition Stands Out

Unlike downstream interventions (STING inhibitors, anti-inflammatories) that treat symptoms, or upstream interventions (dietary restriction) that are impractical for clinical translation, v-ATPase inhibition targets the root cause of HSC aging at the organelle level. Key advantages:

Root Cause

Addresses lysosomal hyperactivation directly, preventing all downstream cascading damage

Ex Vivo Protocol

16h treatment before transplant — avoids systemic drug toxicity entirely

Multi-Domain Reset

Simultaneously fixes metabolic, epigenetic, and inflammatory dysfunction

Lysosomal Dysfunction Estimator

Estimate the degree of lysosomal dysfunction in HSCs based on key measurable parameters. This interactive tool models the relationship between lysosomal markers and predicted HSC functional decline.

Parameter Input
Lysosomal pH (acidity)4.5
3.0 (hyperacidic)5.5 (alkaline)
v-ATPase Activity (% above baseline)0%
LAMP2A Expression (relative)1.0
Cytoplasmic mtDNA Level (fold)1.0×
cGAS-STING Activation (%)10%
Dysfunction Score
12
Healthy
Lysosomal Integrity88%
Metabolic Fitness92%
Inflammatory Burden8%
Repopulation Capacity95%
Dysfunction Domain Radar

References

Primary research papers and reviews underpinning the Lysosomal Rejuvenation Atlas.

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