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Updated: Jan 3, 2026
Isolation, Culture, and Characterization of Primary Dermal Fibroblasts from Human Keloid Tissue
Published on: July 28, 2023
Expression of Cathepsins B, D, and G by the Embryonic Stem Cell-Like Population within Human Keloid Tissues and
Claudia Paterson1, Valerie M Y Lee1, Helen D Brasch1
1From the Gillies McIndoe Research Institute; the Wellington Regional Plastic, Maxillofacial and Burns Unit, Hutt Hospital; and the University of Auckland.
Insights
Cathepsins B, D, and G are found in keloid stem cells, potentially bypassing the renin-angiotensin system. This suggests new therapeutic targets for keloid treatment using cathepsin inhibitors.
Area of Science:
- Biomedical research
- Dermatology
- Cell biology
Background:
- Keloid lesions contain embryonic stem cell-like populations expressing renin-angiotensin system components.
- Dysregulation of the renin-angiotensin system may be involved in keloid development.
Purpose of the Study:
- To investigate the presence and role of cathepsins B, D, and G in keloid stem cells.
- To determine if these cathepsins contribute to renin-angiotensin system bypass loops in keloids.
Main Methods:
- Immunohistochemistry (3,3'-Diaminobenzidine and immunofluorescence) to detect cathepsins B, D, and G.
- Co-staining with CD34, tryptase, and OCT4 to identify cell types.
- Western blotting, RT-qPCR, and enzyme activity assays to assess protein, mRNA expression, and enzyme function.
Main Results:
- Cathepsins B, D, and G were expressed in keloid tissue samples.
- Cathepsins B and D localized to microvessel endothelium, while cathepsin G localized to perivascular cells.
- Functional activity of cathepsins B and D was confirmed, with evidence of transcriptional activation for B, D, and G.
Conclusions:
- Cathepsins B, D, and G are present in keloid stem cells and may bypass the renin-angiotensin system.
- These cathepsins represent potential therapeutic targets for keloid treatment.
- Renin-angiotensin system modulators and cathepsin inhibitors could be explored for keloid therapy.
Background:
The authors have previously shown that an embryonic stem cell-like population within keloid-associated lymphoid tissues in keloid lesions expresses components of the renin-angiotensin system that may be dysregulated. The authors hypothesized that cathepsins B, D, and G are present within the embryonic stem cell-like population in keloid lesions and contribute to bypass loops of the renin-angiotensin system.
Methods:
3,3'-Diaminobenzidine immunohistochemical staining for cathepsins B, D, and G was performed on formalin-fixed paraffin-embedded sections in keloid tissue samples of 11 patients. Immunofluorescence immunohistochemical staining was performed on three of these keloid tissue samples, by co-staining with CD34, tryptase, and OCT4. Western blotting, reverse transcription quantitative polymerase chain reaction, and enzyme activity assays were performed on five keloid tissue samples and four keloid-derived primary cell lines to investigate protein and mRNA expression, and functional activity, respectively.
Results:
3,3'-Diaminobenzidine immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 15 keloid tissue samples. Immunofluorescence immunohistochemical staining showed localization of cathepsins B and D to the endothelium of microvessels within the keloid-associated lymphoid tissues and localization of cathepsin G to the tryptase-positive perivascular cells. Western blotting confirmed semiquantitative levels of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines. Reverse transcription quantitative polymerase chain reaction showed quantitative transcriptional activation of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines and cathepsin G in keloid tissue samples. Enzyme activity assays demonstrated functional activity of cathepsins B and D.
Conclusion:
Cathepsins B, D, and G are expressed by the embryonic stem cell-like population within the keloid-associated lymphoid tissues of keloid lesions and may act to bypass the renin-angiotensin system, suggesting a potential therapeutic target using renin-angiotensin system modulators and cathepsin inhibitors.
