Abstract
Background
Erectile dysfunction (ED) is a common, debilitating complication of diabetes mellitus, driven by endothelial dysfunction, neurovascular injury, and oxidative stress. Although mesenchymal stem cells confer benefit, concerns regarding safety, scalability, and standardization have shifted interest to cell-free therapies. Umbilical cord blood–derived extracellular vesicles (UCB-EVs) are protein-rich with regenerative potential, but their efficacy in diabetic ED remains unknown.
Methods
We isolated and characterized UCB-EVs and evaluated them across in vitro, ex vivo, and in vivo platforms: human umbilical vein and mouse cavernous endothelial cells under high glucose; aortic ring, dorsal root ganglion, and major pelvic ganglion explants; and streptozotocin-induced diabetic mice. Erectile function was quantified by intracavernous pressure after intracavernous UCB-EV delivery (5–20 µg). Mechanistic assays included immunofluorescence, terminal deoxynucleotidyl transferase dUTP nick end labeling, phospho-histone H3, reactive oxygen species staining, western blotting, RNA sequencing, and gene set enrichment analysis.
Results
UCB-EVs enhanced tube formation, migration, and microvessel sprouting under high glucose and promoted neurofilament-positive neurite extension in dorsal root ganglion and major pelvic ganglion explants. In diabetic mice, UCB-EV treatment improved ~ 90% of control intracavernous pressure, preserved PECAM-1–positive endothelial cells and NG2–positive pericytes, and increased neuronal markers—neurofilament and neuronal nitric oxide synthase (nNOS). Mechanistically, UCB-EVs reduced apoptosis and oxidative stress, increased endothelial proliferation, and activated PI3K (phosphoinositide 3-kinase)–Akt signaling. Transcriptomics showed reversal of diabetes-associated programs, enrichment of angiogenic and neurogenic networks, and significant upregulation of the Hallmark E2F Targets gene set, consistent with improved cell-cycle progression and reparative proliferation.
Conclusions
UCB-EVs promote neurovascular repair and functional recovery in diabetic ED by coordinating angiogenesis, neurogenesis, anti-apoptotic signaling, and PI3K–Akt–E2F pathway activation. These findings support UCB-EVs as a promising, safe, and scalable cell-free therapeutic candidate for diabetic ED and justify further studies to define active mediators, durability, and efficacy across diabetic models.
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Abbreviations
- AGEs:
-
Advanced glycation end products
- Akt:
-
Protein kinase B
- ANOVA:
-
Analysis of variance
- BDNF:
-
Brain-derived neurotrophic factor
- BP (GO-BP):
-
Gene Ontology—Biological Process
- CC:
-
Corpus cavernosum
- CC (GO-CC):
-
Gene Ontology—Cellular Component
- cGMP:
-
Cyclic guanosine monophosphate
- CNI:
-
Cavernous nerve injury
- DAPI:
-
4′,6-diamidino-2-phenylindole
- EG(s):
-
Differentially expressed gene(s)
- DM:
-
Diabetes mellitus
- DRG:
-
Dorsal root ganglion/ganlia
- ED:
-
Erectile dysfunction
- eNOS:
-
Endothelial nitric oxide synthase
- EV(s):
-
Extracellular vesicle(s)
- FDR:
-
False discovery rate
- FITC:
-
Fluorescein isothiocyanate
- FPKM:
-
Fragments per kilobase of transcript per million mapped reads
- GAPDH:
-
Glyceraldehyde-3-phosphate dehydrogenase
- GSEA:
-
Gene set enrichment analysis
- HBSS:
-
Hank’s balanced salt solution
- HG:
-
High glucose
- HGF:
-
Hepatocyte growth factor
- HUVEC(s):
-
Human umbilical vein endothelial cell(s)
- ICP:
-
Intracavernous pressure
- IGF-1:
-
Insulin-like growth factor-1
- IRB:
-
Institutional Review Board
- KEGG:
-
Kyoto Encyclopedia of Genes and Genomes
- LDL:
-
Low-density lipoprotein
- MF (GO-MF):
-
Gene Ontology—Molecular Function
- MPG:
-
Major pelvic ganglion/ganlia
- MSBP:
-
Mean systolic blood pressure
- MSC(s):
-
Mesenchymal stem cell(s)
- NG:
-
Normal glucose
- NG2:
-
Neuron-glial antigen-2
- NGF:
-
Nerve growth factor
- NIH:
-
National Institutes of Health
- nNOS:
-
Neuronal nitric oxide synthase
- NO:
-
Nitric oxide
- Ox-LDL:
-
Oxidized low-density lipoprotein
- PBS:
-
Phosphate-buffered saline
- PDE5i:
-
Phosphodiesterase type-5 inhibitor(s)
- PECAM-1:
-
Platelet endothelial cell adhesion molecule-1
- PH3:
-
Phospho-histone H3
- PI3K:
-
Phosphoinositide 3-kinase
- p-PI3K:
-
Phosphorylated PI3K
- PVDF:
-
Polyvinylidene difluoride
- RC:
-
Read count
- RNA-seq:
-
RNA sequencing
- ROS:
-
Reactive oxygen species
- SDS-PAGE:
-
Sodium dodecyl sulfate–polyacrylamide gel electrophoresis
- SEM:
-
Standard error of the mean
- STZ:
-
Streptozotocin
- TEM:
-
Transmission electron microscopy
- TRITC:
-
Tetramethylrhodamine isothiocyanate
- TUNEL:
-
Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling
- UCB:
-
Umbilical cord blood
- UCB-EV(s):
-
Umbilical cord blood–derived extracellular vesicle(s)
- VEGF:
-
Vascular endothelial growth factor
- E2F:
-
E2F transcription factor family
- E2F1:
-
E2F transcription factor 1
Acknowledgements
The manuscript is edited by a professional, native English-speaking editor at Wordvice ([email protected]; Kevin Heintz, Managing Editor, Wordvice).
Funding
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2021-NR060097 to Ji-Kan Ryu), and by additional NRF grants (RS-2024-00450451 to Guo Nan Yin).
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UCB was obtained from healthy full-term deliveries after written informed consent and Institutional Review Board approval (Title: Evaluation of erectile dysfunction treatment efficacy using extracellular vesicles isolated from umbilical cord blood., Number: 2023-11-045, Approved on December, 18th, 2023). All human procedures adhered to the Declaration of Helsinki. Fresh UCB was collected in EDTA-coated tubes and processed within 2–4 h at 4 °C to preserve EV integrity. Animal studies used 8-week-old male C57BL/6J mice (20–25 g; Orient Bio, Korea). Protocols were approved by the Institutional Animal Care and Use Committee of Inha University (Title: Effect of intracavernous administration of human clonal bone marrow-derived stem cells on erectile function in streptozotocin-induced diabetic mouse., Number: 230530-876, Approved on May, 30th, 2023).
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Fridayana, F.R., Yin, G.N., Huang, Y. et al. Umbilical cord blood–derived extracellular vesicles improve erectile function in diabetic mice via PI3K-Akt-E2F–mediated neurovascular regeneration. Stem Cell Res Ther (2026). https://doi.org/10.1186/s13287-026-05352-3
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DOI: https://doi.org/10.1186/s13287-026-05352-3