Stem cell therapy refers to the clinical use of stem cells to influence tissue repair and inflammation. In modern regenerative medicine, most treatments use mesenchymal stromal/stem cells (MSCs), which primarily work through signaling and immune modulation rather than directly replacing damaged tissue.
What Are Stem Cells?
Stem cells are undifferentiated cells with two defining characteristics:
- Self-renewal – the ability to replicate.
- Differentiation – the ability to mature into specialized cell types under specific conditions.
There are multiple categories of stem cells:
- Pluripotent stem cells (e.g., embryonic stem cells) can form nearly any cell type.
- Multipotent stem cells, such as mesenchymal stem cells (MSCs), have more limited differentiation capacity.
Most clinical regenerative medicine programs use mesenchymal stromal/stem cells (MSCs).
What Are Mesenchymal Stem Cells (MSCs)?
Mesenchymal stem cells are multipotent progenitor cells that can be isolated from:
- Bone marrow
- Adipose tissue
- Umbilical cord tissue
- Other connective tissues
They are defined by:
- Adherence to plastic in culture
- Specific surface marker expression (CD73, CD90, CD105)
- Lack of hematopoietic markers (CD34, CD45)
- Ability to differentiate into bone, cartilage, and fat cells under laboratory conditions
These defining criteria were established by the International Society for Cellular Therapy (ISCT). Importantly, in clinical settings, MSCs are not primarily used to “become new cartilage” or “turn into new neurons.” Their main therapeutic value lies elsewhere.
The Replacement Myth vs. Biological Reality
A common misconception is that stem cell therapy works by injecting cells that physically replace damaged tissue.
- “The stem cells become new cartilage.”
- “The stem cells turn into new brain cells.”
- “The stem cells rebuild the joint.”
In most clinical applications using MSCs, this is not the dominant mechanism. The modern scientific understanding is that MSCs function primarily through paracrine signaling and immunomodulation, not bulk tissue replacement. Direct structural replacement has limited evidence in human orthopedic and neurologic settings.
What Is Paracrine Signaling?
Paracrine signaling refers to the release of bioactive molecules that influence nearby cells. MSCs secrete a broad range of signaling factors, including:
- Growth factors (e.g., VEGF, HGF)
- Anti-inflammatory cytokines (e.g., IL-10)
- Extracellular vesicles and exosomes
- Chemokines that influence immune cell behavior
These secreted molecules can:
- Reduce inflammatory signaling
- Support blood vessel formation
- Influence local immune cell activity
- Promote a more favorable tissue microenvironment
A review in Nature Reviews Molecular Cell Biology discusses how MSCs exert therapeutic effects largely through secreted factors rather than engraftment. In many studies, injected MSCs do not permanently engraft into tissue. Instead, they act as temporary biological modulators.
What Is Immunomodulation?
Immunomodulation means adjusting immune system behavior. In chronic degenerative and inflammatory conditions, the immune system may remain persistently activated. MSCs can influence immune cells such as:
- T lymphocytes
- B lymphocytes
- Natural killer cells
- Macrophages
MSCs can shift macrophages from a pro-inflammatory (M1) phenotype toward an anti-inflammatory (M2) phenotype in experimental models. This shift may reduce chronic inflammation that contributes to:
- Osteoarthritis
- Disc degeneration
- Autoimmune processes
- Certain neurologic inflammatory conditions
A review in Blood outlines the immunomodulatory properties of MSCs. The therapeutic goal is not to suppress immunity entirely, but to rebalance dysregulated inflammatory signaling.
Do Stem Cells Permanently Stay in the Body?
In many studies involving intravenous MSC administration, cells are detectable transiently and may localize initially in the lungs before gradually decreasing.
For example, a study in Frontiers in Immunology showed that intravenously administered MSCs were short-lived and did not migrate extensively beyond the lungs in animal models:
This supports the idea that therapeutic effects are mediated largely through signaling rather than long-term tissue integration.
What Stem Cell Therapy Is — and What It Is Not
Stem cell therapy is:
- A biologic signaling intervention
- A method to influence inflammation and tissue environment
- An evolving area of regenerative medicine
Stem cell therapy is not:
- Instant tissue replacement
- Guaranteed structural regeneration
- A universal cure
- A substitute for necessary surgical correction
Understanding this distinction is critical for setting realistic expectations
Why Manufacturing and Cell Quality Matter
The biological activity of MSCs depends on:
- Passage number
- Viability
- Sterility
- Surface marker stability
Stem cell therapy, in modern medical practice, typically refers to the use of mesenchymal stromal/stem cells (MSCs) to influence inflammation and tissue repair through paracrine signaling and immunomodulation.
Contrary to popular belief, MSCs do not primarily work by directly replacing damaged tissue. Their clinical effect is largely mediated by biological signaling that alters the tissue microenvironment.
Ongoing research continues to refine understanding of dosing, delivery methods, and long-term outcomes.
About EDNA Wellness
EDNA Wellness is a surgeon-led regenerative medicine center in Bangkok, specializing in orthopedic and neurological conditions using Umbilical Cord–Derived Mesenchymal Stem Cells (UC-MSCs).
All cases are reviewed by orthopedic surgeons and neurosurgeons, with a focus on clinical indication, patient safety, and realistic treatment expectations. Stem cell therapy is recommended selectively, and alternative treatments are considered when more appropriate.
For more information or to book a consultation:
LINE: @ednawellness
WhatsApp: +66 (0) 64 505 5599
www.ednawellness.com