The effectiveness of stem cell therapy may vary from patient to patient for a number of reasons related to individual characteristics of the body, the condition of the disease, and factors that affect the success of the therapy. Here are the main factors that explain why stem cells help some people and not others:
1. Individual characteristics of the immune system
One of the key factors is the reaction of the patient’s immune system to the transplanted stem cells. In some patients, the immune system may reject these cells, which reduces the effectiveness of the treatment. In other cases, the transplanted cells may successfully integrate, leading to positive results.
Immune rejection: The body may perceive the injected stem cells as foreign and try to destroy them. The human immune system is designed to protect the body from any potential threats, including foreign cells and tissues, such as viruses, bacteria, and transplanted cells. In the case of a stem cell transplant, the immune system may recognize them as foreign due to differences in histocompatibility antigens (for example, HLA – Human Leukocyte Antigen). If the antigens of the transplanted cells differ from the patient’s antigens, the immune system activates a protective response aimed at destroying these cells.
Main mechanisms of immune rejection
Activation of T lymphocytes: When immune cells recognize foreign antigens on the surface of transplanted stem cells, they activate T lymphocytes. These cells begin to attack the transplanted tissues, causing damage or complete destruction.
Antibody production: The immune system can also produce antibodies against stem cell antigens, which helps destroy them.
Inflammatory response: The immune reaction is often accompanied by inflammation in the transplant area, which can lead to damage and death of the transplanted cells.
Immune tolerance: In some cases, the body does not reject the cells, which ensures successful integration and the effect of the treatment. This is the ability of the body’s immune system not to react aggressively to its own cells, tissues, and harmless external antigens, such as stem cells. It is a critical mechanism for preventing autoimmune diseases and ensuring the normal functioning of the immune system.
The immune system recognizes various molecules as “self” (its own cells and tissues) and “foreign” (harmful microorganisms, viruses, and other foreign elements). When immune tolerance is broken, the body begins to attack its own cells, which leads to autoimmune diseases.
2. Disease stage
Early stages of the disease are usually more amenable to stem cell treatment. For example, in type 1 diabetes, if the beta cells are not yet completely destroyed, there is a chance of restoring their function. In advanced stages of the disease, when a significant portion of the cells have already been destroyed, the effectiveness of stem cell treatment may be lower.
Early stage: Residual cells can be supported or restored, which improves the results.
Late stage: The damage may be so severe that even stem cells cannot compensate for it.
3. Quality and type of stem cells
The type and quality of stem cells used can significantly affect the success of treatment. Different types of stem cells (embryonic, induced pluripotent, mesenchymal) have different abilities to differentiate and restore damaged tissues.
Embryonic stem cells have a high ability to differentiate, but can be difficult to use due to a number of additional tests for compatibility with the recipient.
Mesenchymal stem cells are more often used for immunomodulation, but their ability to restore specific tissues can be limited.
Progenitor cells are a type of stem cell that are at an intermediate stage of development between pluripotent stem cells and specialized (differentiated) cells in the body. They have the ability to differentiate (become) one or more types of mature cells
Examples of progenitor cells:
Hematopoietic progenitors: These cells are found in the bone marrow and give rise to the different types of blood cells – erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. They are derived from hematopoietic stem cells, but are specialized for blood formation.
Myoblasts (muscle cell progenitors): Myoblasts are progenitor cells that differentiate into muscle fibers. They are involved in the growth and repair of muscle tissue after injury.
Neural progenitors: These cells are derived from neural stem cells and can differentiate into various types of cells in the nervous system, such as neurons, astrocytes, or oligodendrocytes.
Epidermal progenitors: These cells can develop into skin cells (keratinocytes) and are involved in the renewal and healing of the skin.
The quality of the cells may also depend on the source, storage conditions, and preparation method for transplantation.
4. The body’s response to therapy
Each patient’s body responds differently to stem cell transplantation. Age, the presence of concomitant diseases, and genetic characteristics may have an impact. For example:
Age: In younger patients, regenerative processes may proceed more quickly and successfully. Comorbidities: Chronic inflammatory or autoimmune diseases may worsen treatment results.
5. Stem cell administration technique
The method of administering stem cells can greatly affect the outcome. It is important to choose the right place and method of administration (e.g. intravenously, subcutaneously or directly into the affected organ). Incorrect administration may reduce the effectiveness of the cells or even cause complications.
6. Timing and duration of therapy
For some patients, the effect of stem cells may be cumulative, and several therapy sessions may be required to achieve positive results. It is important to keep in mind that the results may not be immediate, and it takes time for regenerative processes to activate.
7. Initial level of damage
The level of tissue or organ damage can affect the results of treatment. For example, if too many beta cells are destroyed in the pancreas due to type 1 diabetes, stem cells may not be able to restore them completely.
8. Genetic and epigenetic factors
A patient’s genetic predisposition may also affect the effectiveness of stem cell treatment. For example, people with certain genetic mutations may have reduced tissue regenerative capacity. In addition, epigenetic changes (environmental, dietary, and lifestyle influences) can alter the body’s response to therapy.
9. Effectiveness of combination therapy
Stem cells are often used in combination with other treatments (e.g., immunomodulation or medications). The effectiveness of this combination approach may vary for each patient, and its success depends on the individual treatment regimen.
Conclusion
The effectiveness of stem cell therapy depends on many factors, including the characteristics of the immune system, the stage of the disease, the quality of the cells, the method of their administration, and other factors. It is important to consider that stem cell therapy is still relatively new and requires an individual approach for each patient, as well as further research to improve treatment results.