To perform their function in the body, some cells must move from one place to another. During this cell migration, they make use of cellular structures while being attracted to foreign substances. Misdirected cells contribute to the development and exacerbation of diseases such as cancer, multiple sclerosis, and atherosclerosis.
What is cell migration?
The term “cell migration” refers to the movement of a cell within the organism. The majority of cells are constantly in motion. In cell migration, there are undirected migratory movements and goal-directed ones, depending on the type of cell involved and the task it has to perform (building new tissue, defending against pathogens, etc.). Targeted movements usually occur as a result of triggers such as certain attractants. Many cell migrations are useful for the organism. Others, however, cause the development of diseases or aggravate existing diseases. Sometimes even the same molecule is used for supporting and damaging cell migrations. In cell migration, cells move in different ways. For example, in phase 1 of movement, the cell extends its projections and hooks some of them into the substrate. In this way, it establishes the direction of its movement. In phase 2, the anchored projections pull the cell in the specified direction and then disengage. The direction of cell migration is determined by the Golgi apparatus present in each cell. Thanks to modern laser microscopy and innovative protein labeling techniques, cell migration can now be studied in detail.
Function and task
Cell migration has different goals. The germline cells present in the embryo migrate to where the respective sex organ will later form. In the germline cells of the zebra fish embryo, for example (in which cell migration, which is still quite unknown, has already been studied more extensively), cell migration occurs with the help of the proteins that originally held the blastomeres together (E-cadherins), the transcription factor Oct4, and the epidermal growth factor EGF. The former blastomeres attach themselves to neighboring cells with the sticky E-cadherins and pull themselves along them. Other cells migrate to their target site and there join together with other cell types to form a cell association (organ). Immune cells first drift aimlessly in the bloodstream and then pounce on pathogens to eliminate them: Leukocytes use chemokine receptors such as Cxcr4b to seek out dangerous pathogens. Chemokines are molecules that act as signposts during cell migration. Other leukocytes repair the inner wall of blood vessels damaged by atherosclerosis. They move along with the bloodstream and attach themselves to the cells of the vessel wall. They then scan the wall surface with their projections. If they perceive the chemical signal of an inflamed cell, they flatten out and try to pass the boundary between the vessel wall cells. In doing so, they are thought to mimic the chemical signal of the inflamed cell, which serves as a key for them.
Symptoms, complaints, and signs
Cell migration in the organism is a normal process that usually goes unnoticed. On the contrary, the absence of cell migration of certain cells would question the viability of the organism. For example, immune cells must constantly migrate through the organism to protect it from pathogens. However, in the process of fighting infection, they generate inflammation at the site of infection. The tissue heats up there. If the pathogens have already spread in the body, the body temperature increases. Here, cell migration of immune cells is a normal consequence of infection, which then produces the typical signs of disease due to the struggle of the outflowing immune cells with the pathogens. However, immune cells can also be misdirected and attack the body’s own tissue, causing a wide variety of symptoms. These are then autoimmune diseases. Multiple sclerosis, for example, is an autoimmune disease. Here, the insulating layer of nerve cells is destroyed. The patient suffers from paralysis, visual disturbances and sensory disturbances of the skin. In addition, there is premature exhaustion, concentration disorders, impaired memory, depression and much more. Arteriosclerosis is also caused by incorrect cell migration.Thus, the immune cells migrate to the stuck cholesterol on the vessel walls and try to break it down. In this attempt, they turn into so-called foam cells, which can clog the blood vessels as plaques. Finally, one of the negative aspects of cell migration is the spread of cancer cells in the organism. This results in metastases in other organs, which make curative cancer treatment difficult or even impossible.
Diseases and ailments
If cells in the body do not migrate as they should, diseases result. Enzymes such as matrix metalloproteases (MMPs) make vessel walls and tissues so full of holes that errant cells can pass through them. SDF-1, the factor responsible for zebrafish germline cell migration, is also used for damaging “work” in the body: It is also involved in the formation of cancer metastases, the development of arthritis, and the spread of HIV infection in the body. Inside the metastatic cells of some cancers are MAPKs, proteins that trigger cell migration, initiate cell division, and are even responsible for cell degeneration. MAP kinases are held in the nucleus by a protein called STYX (pseudophosphatase). If the enzyme is destroyed, the cell’s Golgi apparatus also divides, so that the cell is no longer capable of purposeful migration. Since breast cancer patients, for example, are found to have greatly increased levels of the STYX protein, scientists believe that an effective anticancer drug would have to be designed to turn off STYX in order to prevent the cancer from metastasizing. The epidermal growth factor EGF also appears to play a critical role in cancer cell migration. If its receptor is destroyed by a mutation, EGF is permanently active: it permanently stimulates cancer cells to migrate. Skin cancer cells have developed a special way to carry out cell migration. They simply turn vesicles inside out and restructure their flexible cell skeleton in the process. In multiple sclerosis, immune cells are reprogrammed to attack not only harmful pathogens but also healthy cells. The pathogens form structures on their cell surface that resemble those of the body’s own cells and thus attract the immune cells. The immune cells then eat them, imprint the molecular structure on themselves and subsequently attack healthy endogenous cells as well. The transformed immune cells move even more aggressively through the body because they now have even more molecules with which to move through tissue. They can even pass the blood–brain barrier, which is insurmountable for most substances. In the brain, they attack healthy tissue, triggering the relapses so feared by MS patients: They deactivate the cells that build up the protective myelin layer around the nerve cells. This permanently weakens the nerve cells and disrupts the transmission of information.
Complications
Cell migration is a natural process in the body that does not normally cause complications. However, when cells in the body do not migrate as intended, disease can occur. Depending on the location in the body where cell misdirection occurs, this can lead to harmless temporary symptoms, but also to serious diseases such as cancer or multiple sclerosis. Misdirected cells are favored by enzymes such as matrix metalloproteases. These damage vessel walls and tissues, thereby enabling cells to be misdirected to other regions of the body. Other enzymes and substances can also cause cell migration and thus promote diseases such as arthritis and cancer. Misdirected cells also promote the spread of HIV in the body. There is also an increased risk of multiple sclerosis, nerve damage and countless other diseases and symptoms, each of which is associated with serious complications. Cell migration itself is not problematic, but the processes that are set in motion by it have serious consequences on health. It is not possible to treat cell migration because it occurs within the smallest molecules and the misdirection is random.
When should you see a doctor?
In many cases, cell migration is not noticed by the affected person until it is too late. Often, there are diffuse health irregularities that cannot be explained initially.A check-up visit to a doctor should therefore always be made at regular intervals. The general state of health is recorded and compared with the standard values. If there are any abnormalities, it is possible to react immediately. In addition, a visit to the doctor is necessary if there are disturbances in concentration or attention, behavioral abnormalities or a general feeling of being unwell. If the affected person suffers from a depressed mood and daily obligations can no longer be fulfilled as usual, there is a need for action. If there are disturbances in vision or mobility, a doctor should be consulted as soon as possible. The need for medical care is also given in case of paralysis and disturbances of sensibility. If swelling is noticed on the body, if there are changes in the appearance of the skin or if participation in social life decreases, these complaints should be discussed with a doctor. If irregularities such as headaches or fever appear, the affected person requires medical treatment. If premature exhaustion occurs repeatedly during the course of the day despite a restful night’s sleep, this is to be regarded as an indication of a health disorder. Examinations are necessary to enable a diagnosis to be made.
Follow-up
The aftercare of a misdirected cell migration depends on the cause. For cancer or multiple sclerosis, follow-up occurs once the condition has been cured. It may include follow-up medical examinations, discussions with therapists, or more extensive visits to specialists. During follow-up care, the trigger for the misdirected cells is remedied, insofar as this is possible. In the case of cancer, for example, a change in lifestyle habits is necessary. This can prevent the cells from being misdirected again. Follow-up care is provided by the responsible medical specialist. Which medical specialist is responsible also depends on the underlying disease. If necessary, several physicians are involved, for example to instruct a final physiotherapy or to control the drug treatment. Depending on the cause, nutritionists or sports medicine specialists may also be part of the follow-up. Patients should have regular medical checkups following treatment. After a certain age, routine cancer screening exams are covered by health insurance. It is important to discuss the options for follow-up care with the family doctor and to take the necessary steps together with a specialist. Depending on the disease, follow-up of misdirected cell migration can be a long-term process that needs to be adjusted again and again.
Here’s what you can do yourself
The process of cell migration is a natural process that cannot be consciously perceived or controlled. For this reason, the possibilities of self-help are limited in case of disturbances and irregularities of any kind. On the whole, the affected person can pay attention to the observance of a healthy lifestyle and should immediately seek the cooperation of a physician in case of existing health problems or limitations of functional abilities. If swelling or other abnormalities occur, check-ups are necessary. For prevention, preventive health measures can be initiated at regular intervals. In every age group there is the possibility to have the general state of health checked by the family doctor. This offer should be used over the entire life span. If the general susceptibility to infection increases, increased attention is required. With a healthy lifestyle, a balanced diet, adequate exercise and a self-weight in the normal range of the BMI, it is considered a cause for concern if inflammations or infections increase. A persistently slightly elevated body temperature should also be interpreted as a warning signal from the organism. In order to prevent functional disorders from occurring, for example, work should be carried out under optimal lighting conditions and the organism should be protected from general states of stress. Balanced sleep prevents disturbances in concentration or memory. Emotional and physical stressors should also be reduced to a minimum.
