Regenerative medicine is a cutting-edge medical field that aims to restore the function of tissues and organs damaged by disease or injury.
It enables regeneration of tissues that were difficult to repair with conventional treatments and seeks therapies with fewer side effects by leveraging a patient’s own cells.
Among these, stem cells are special cells with the ability to differentiate into various cell types in the body (multipotency) and the capacity to self-renew (self-replication).
By taking advantage of these properties, stem cells are being widely applied to tissue regeneration and disease treatment; research and practical use are advancing across many areas, including neurological, cardiac, and joint disorders, as well as immune-related therapies.
Types of Stem Cells
There are three major types of stem cells used in regenerative medicine.
- ES cells (Embryonic Stem Cells): Derived from the embryo of a fertilized egg and capable of differentiating into all cell types; however, their use is restricted due to ethical concerns.
- iPS cells (Induced Pluripotent Stem Cells): Created by reprogramming somatic cells; although highly potent, they carry a risk of tumor formation.
- Somatic (Adult) Stem Cells: Already present in the human body; currently the most practical with high safety and without ethical issues.
| Type of Stem Cell | Pluripotency | Differentiation Capacity | Challenges in Use |
|---|---|---|---|
| ES Cells (Embryonic Stem Cells) |
High | Can differentiate into all cell types |
Ethical concerns; risk of tumor formation |
| iPS Cells (Induced Pluripotent Stem Cells) |
High | Can differentiate into all cell types |
Risk of tumor formation; technical challenges |
| Somatic Stem Cells (Adult Stem Cells) |
Lower | Can differentiate into limited cell types |
Limited harvest volume; declining proliferative capacity |
In regenerative medicine today, somatic (adult) stem cells—already present within our bodies—are considered the safest and most practical option.
Types of Somatic Stem Cells
Stem cells located in various tissues include many types such as hematopoietic, neural, skin, intestinal, mammary, testicular, and mesenchymal stem cells.
Stem cells possess “self-renewal,” which expands their own population, and “differentiation capacity,” which enables them to divide and become diverse cell types.
Among somatic stem cells, mesenchymal stem cells (MSCs)—which differentiate into the widest variety of cell types—are central to current stem cell therapies, with potential across blood, neural, epidermal, cartilage, muscle, liver, heart, and more.
Types of Mesenchymal Stem Cells
Mesenchymal stem cells (MSCs) are found in bone marrow, adipose tissue, and the umbilical cord, and can differentiate into a variety of cells such as bone, cartilage, fat, nerve, and muscle.
They also have tissue-repair and immunomodulatory functions and are being applied to treat various diseases—particularly in joint, neurological, cardiovascular, and autoimmune fields—where research and clinical use are advancing.
MSCs used in regenerative medicine are broadly categorized into three types based on their source.
Bone Marrow–Derived MSCs
- Once the mainstay of regenerative medicine, now increasingly supplanted by other MSC sources.
- Exhibit a balanced combination of self-renewal and differentiation capacities.
- Relatively strong immunomodulatory effects; applied in autoimmune indications.
Adipose-Derived MSCs
- Low burden on the body and allow harvesting of large numbers of cells (via liposuction under local anesthesia).
- Easy to culture and proliferate in a relatively short time.
- Demonstrate anti-inflammatory effects; applied to inflammatory disorders.
Umbilical Cord–Derived MSCs
- Highest proliferative capacity and cellular “youth” retained.
- Low immunogenicity and suitable for allogeneic use (low risk of rejection).
- Easy to obtain with few ethical concerns (collected from neonatal umbilical cords with no donor burden).
- Secrete abundant growth factors and anti-inflammatory cytokines, supporting therapeutic effects.
| Ease of Collection | Proliferative Capacity | Differentiation Capacity | Immunomodulatory Capacity | Use Type (Autologous/Allogeneic) |
|
|---|---|---|---|---|---|
| Bone Marrow–Derived | Difficult | Medium | High | High | Allogeneic |
| Adipose-Derived | Moderate | High | Low–Medium | Medium | Mainly autologous |
| Umbilical Cord–Derived | Easy | Very high | High | Very high | Allogeneic |
- Autologous Stem Cells: Cells harvested from the patient’s own body are cultured/expanded and then reinfused.
- Allogeneic Stem Cells: Cells harvested from healthy donors are used for treatment.
Three Key Effects of Mesenchymal Stem Cells
Mesenchymal stem cells (MSCs) can repair diverse tissues and modulate immunity. Their actions are realized primarily through the following three mechanisms.
Pathotropism Effect
When inflammation or tissue injury occurs, MSCs sense local chemokines (inflammatory signals) and migrate via the bloodstream to the damaged site. This property allows MSCs to accumulate near injured tissues and initiate repair. In particular, by interacting with fibroblasts, endothelial cells, and immune cells, MSCs suppress inflammation and promote tissue recovery.
Homing Effect
After migrating to inflamed or injured areas, MSCs home (engraft) there and contribute to repair. Locally, MSCs may differentiate into needed cell types and secrete cytokines and growth factors that support functional recovery of damaged tissues.
Inflamed sites contain elevated inflammatory cytokines and growth factors that attract MSCs. Responding to these signals, MSCs interact with endothelial cells and fibroblasts to drive tissue repair.
Paracrine Effect
MSCs secrete bioactive factors—such as cytokines, growth factors, and exosomes—that promote repair of damaged tissues. Thus, even without directly differentiating, MSCs can support functional recovery of surrounding cells. They also modulate immune cell activity and suppress inflammatory responses.
This effect is especially important in the treatment of autoimmune and chronic inflammatory diseases, where MSCs adjust immune activity while curbing excessive inflammation.
Benefits of Umbilical Cord (Wharton’s Jelly)–Derived MSCs
Umbilical cord (Wharton’s jelly)–derived MSCs have characteristics that make them highly promising therapeutically.
Considering only risks such as immune rejection, autologous cells may seem safest; however, their proliferative and differentiation capacities decline with age.
In addition, prior medical history and age-related changes can be reflected in cultured cells, potentially increasing certain risks.
Autologous cells are, after all, one’s own cells whose function has diminished with age.
Umbilical cord–derived (Wharton’s jelly) MSCs are collected from the Wharton’s jelly of a newborn’s umbilical cord, so they are free from age-related cellular deterioration—an important advantage.
Umbilical tissue is rich in MSCs, and compared with bone marrow– or adipose-derived sources, these cells exhibit higher proliferative capacity and can maintain differentiation potential over longer periods.