Key Takeaways
- CD90 (also called Thy-1) is a protein on the surface of several cell types, including mesenchymal stromal cells (MSCs), fibroblasts, and neurons.
- It is one of the markers researchers use to identify MSCs, but it is not specific to any single cell type.
- CD90 expression alone does not confirm that a cell is functional or that a treatment will work.
- Reliable cell identification uses a full marker panel plus functional testing, not one surface protein.
- Understanding what CD90 does and does not tell you helps when evaluating options at a Vega stem cell clinic or any provider offering cell-based therapies.
CD90, also known as Thy-1, is a small protein anchored to the outside of cells. It was first identified decades ago during research on thymus cells and has since been found on a wide range of cell types across the body. In regenerative medicine, the CD90 marker is best known as one of the markers used to characterize mesenchymal stromal cells (MSCs), the cell type most commonly referenced in cell therapy and tissue repair research.
CD90 is important for patients seeking regenerative treatments, as it’s a term used to explain how they confirm the cells in their treatments. Knowing what it conveys and what it omits aids in formulating superior inquiries.
What Is CD90 and How Does It Work?
A cell-surface marker is a protein sitting on the outside of a cell that researchers can detect using laboratory techniques such as flow cytometry (a method that sorts and counts cells by their surface proteins) or immunostaining. CD90 is a cell-surface protein, specifically a GPI-anchored glycoprotein, meaning it attaches to the outer wall of the cell using a small lipid anchor rather than passing through it. Because it sits on the surface, laboratory technicians can identify and sort these live cells without destroying them. It plays roles in cell-to-cell communication, adhesion, and signaling, though its full range of functions is still being studied.
How CD90 Is Used to Identify Different Cell Types
CD90 appears across many cell types. The main populations that express it include:
- Mesenchymal stromal cells: a widely referenced standard from the International Society for Cellular Therapy (ISCT), the professional body that sets criteria for defining these cells, lists CD90 as one of three positive markers, alongside CD73 and CD105, that at least 95% of human MSCs should express. CD90 is part of a panel, not a standalone identifier.
- Fibroblasts: the cells that produce collagen and maintain connective tissue also express CD90, which is a key reason the marker alone cannot confirm a cell’s identity.
- Bone marrow cells: CD90-positive populations here include both stromal cells and hematopoietic progenitors (the progenitor cells responsible for forming blood cells), so additional markers are needed to tell them apart.
- Other cell types: CD90 has also been detected on neurons and activated endothelial cells, certain thymocytes, and some cancer cells.
Why CD90 Cannot Identify a Cell on Its Own
Marker expression and biological function are two different things. A cell expressing CD90 has that protein on its surface, but that does not automatically mean it can differentiate into bone, cartilage, or fat, or release therapeutic signaling molecules. Context matters too: the tissue source and culture conditions affect how CD90 expression should be interpreted. Rigorous characterization uses a full marker panel plus functional testing, not a single surface protein.
What CD90 Tells You About a Regenerative Treatment
When a clinic points to CD90 to describe its cells, that data confirms the cells carry a surface protein and little more. It helps to know what a marker can and cannot establish:
What CD90 can tell you:
- A cell carries the CD90 surface protein, detectable by flow cytometry and similar lab methods.
- Combined with CD73 and CD105, the cells meet the ISCT panel used to define MSCs.
What CD90 cannot tell you:
- Whether the cells are alive, active, or will behave as intended once administered.
- Whether the treatment has been studied for your specific condition.
- That marker-positive equals clinically effective, since a marker describes what cells are, not what a treatment achieves.
Evidence for a clinical benefit comes from published research and trial data on the condition being treated. When exploring stem cell therapy Bangkok options, it is reasonable to ask a provider to separate the two: what the cells are, and what the evidence shows they can do.
What to Ask When Exploring Cell Therapy in Bangkok
To make an informed decision about regenerative treatment, you need to know about the cells involved. When speaking with a provider, consider asking:
- What type of cells are used? Whether the treatment uses live cells, cell-derived products such as conditioned media or exosomes, growth factors, or another approach
- How are the cells characterized? A provider should be able to explain which markers they test for and what quality controls are in place
- What evidence supports this for my condition? Ask about published research, clinical trial data, and realistic expected outcomes
- Is a medical assessment performed first? A proper evaluation should happen before any regenerative therapy is recommended
Explore Stem Cell Therapy at Vega Dermatology & Wound Care Unit
CD90 is a useful research tool, but it is one marker among several and cannot, on its own, confirm what a cell will do or how a treatment will perform. The effectiveness of cell-based treatments is still being researched and differs depending on the illness. This is why a truthful healthcare provider will clarify the treatment’s procedures and limitations. Clarity is more important than any specific laboratory term.
At Vega stem cell clinic in Bangkok, regenerative treatments are delivered through a physician-led framework covering wound care, skin repair, hair restoration, and scar remodeling. Assessment with our qualified physicians determines whether a regenerative approach is appropriate for your condition and what it would involve. Care is overseen by Dr. Ekkaparb Charoensuk, an integrative and regenerative medicine physician with more than 15 years of clinical experience.
Book a consultation with our clinical team for an assessment of your condition and to explore stem cell therapy in Bangkok.
References:
- Minimal Criteria for Defining Multipotent Mesenchymal Stromal Cells. The International Society for Cellular Therapy Position Statement. Retrieved August 18, 2026, from https://pubmed.ncbi.nlm.nih.gov/16923606/
- CD90/Thy-1, a Cancer-Associated Cell Surface Signaling Molecule. Retrieved August 18, 2026, from https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2019.00066/full
- Thy-1: More Than a Marker for Mesenchymal Stromal Cells. Retrieved August 18, 2026, from https://faseb.onlinelibrary.wiley.com/doi/full/10.1096/fj.201802224R
- Commonly Used Mesenchymal Stem Cell Markers and Tracking Labels: Limitations and Challenges. Retrieved August 18, 2026, from https://pmc.ncbi.nlm.nih.gov/articles/PMC3839663/
Frequently Asked Questions About CD90 (FAQs)
What is CD90 a marker for?
CD90 is a cell-surface protein found on several cell types, including mesenchymal stromal cells, fibroblasts, neurons, and activated endothelial cells. In regenerative medicine, it is most commonly referenced as one of the markers used to characterize MSCs, but it is not exclusive to any single cell type.
Is CD90 a fibroblast marker?
CD90 is expressed by fibroblasts, but it is not a fibroblast-specific marker. It appears on multiple cell types, so detecting CD90 on a cell does not confirm it is a fibroblast. Researchers use additional markers and functional tests to distinguish fibroblasts from other CD90-positive populations.
What is CD90 in bone marrow?
In bone marrow, CD90 is expressed by mesenchymal stromal cell populations and certain hematopoietic progenitors. It helps researchers sort and characterize bone marrow cell fractions but needs to be used alongside other markers to identify specific cell types within the marrow.
Is CD90 a surface marker?
Yes. CD90 is anchored to the outer surface of the cell membrane by a lipid link (GPI anchor), which makes it detectable without breaking the cell open. This is why it is useful for sorting live cells in the laboratory using techniques like flow cytometry.
Can CD90 alone confirm that a cell is a mesenchymal cell?
No. The ISCT criteria require MSCs to express CD73, CD90, and CD105 while lacking hematopoietic markers. CD90 alone is insufficient because it is shared across too many cell types. A reliable characterization always uses a full marker panel.
The Vega Derma Medical Team consists of board-certified dermatologists, specialized trichologists, and clinical researchers based in Bangkok, Thailand. Our team specializes in evidence-based regenerative dermatology, complex tissue repair, and advanced hair restoration (including precision FUE and FSE). Every protocol and article we publish is medically reviewed to ensure it meets international clinical standards, providing safe, science-backed guidance for our local and international patients.
