Stem-cell therapy is the use of stem cells to treat or prevent a disease or condition.
Stem cells can propagate an unlimited fashion and differentiate essentially any specialized cell type.
Pluripotent stem cells are generated from fully differentiated somatic cells by the transient overexpression of four transcription factors.
Bone marrow transplant is the most widely used stem-cell therapy, but some therapies derived from umbilical cord blood are also in use.
Most stem cells intended for regenerative therapy are generally isolated either from the patient’s bone marrow or from adipose tissue.
Hematopoetic stem cells travelling in the blood stream and possess equal differentiating ability as other mesenchymal stem cells.
Mesenchymal stem cells can differentiate into the cells that make up bone, cartilage, tendons, and ligaments, as well as muscle, neural and other progenitor tissues, they have been the main type of stem cells studied in the treatment of diseases affecting these tissues.
Stem-cell therapy has become controversial following developments such as the ability to isolate and culture embryonic stem cells, to create stem cells using somatic cell nuclear transfer and their use of techniques to create induced pluripotent stem cells.
Embryonic stem cell therapy is complicated by immune incompatibility and possible development of malignancy from administered cells.
The paracrine soluble factors produced by stem cells, the stem cell secretome, has been found to be the predominant mechanism by which stem cell-based therapies mediate their effects in degenerative, auto-immune and inflammatory diseases.
Stem cells are thought to mediate repair via five primary mechanisms:
provide an anti-inflammatory effect,
homing to damaged tissues and recruiting other cells, such as endothelial progenitor cells, that are necessary for tissue growth,
supporting tissue remodeling
inhibiting apoptosis
differentiating into bone, cartilage, tendon, and ligament tissue.
To promote tissue regeneration, platelet-rich plasma could be used in conjunction with stem cell transplantation.
Stem cells have low survival rates at the disease site.
Stem cells have also been shown to have a low immunogenicity due to the relatively low number of MHC molecules found on their surface.
Cell stems have been found to secrete chemokines that alter the immune response and promote tolerance of the new tissue.
This allows for allogeneic treatments to be performed without a high rejection risk.
There is a relationship between therapeutic effect and the number of cells administered.
Healthy adult brains contain neural stem cells which divide to maintain general stem-cell numbers, or become progenitor cells.
For cardiac repair-most patients have had myocardial infarction prior to the use of stem cell therapy.
For cardiac repair is to restore cardiac function and prevent left ventricular remodeling after myocardial infarction.
For cardiac repair-meta-analyses confirmed that modest improvements in left ventricular ejection fraction, associated with therapy after myocardial infarction.
For cardiac repair-some fun links have suggested that patients with the most severe myocardial infarction’s benefit the most.
For cardiac repair-the REGENT trial showed no benefit from cell therapy following myocardial infarction (Tendera).
For cardiac repair-most trials use unfractionated or mononuclear bone marrow cells injected into the infarct related artery within a few days of myocardial infarction.
For cardiac repair-after myocardial infarction stem cell therapy provides no benefit with preserved left ventricular ejection fraction, but in patients with large myocardial infarction is in reduced left ventricular ejection fraction may benefit.
Intracoronary bone marrow stem cell therapy does not offer a functional or clinical benefit.
For bone repair-in most studies mesenchymal stem cells have been used.
Mesenchymal stem cells has the ability to differentiate to bone and cartilage and can be expanded easily in culture and have immunosuppressive properties.
Mesenchymal stem cells have been injected directly in to the head of the femur, with success not only in bone regeneration, but also in pain reduction.
Capabiliy of mesenchymal stem cells in the repair of epidermal tissues.
Studies generally have not shown stem cell therapy to be safe or effective in randomized clinical trials.
Reports of blindness, other lifelong disabilities, series bacterial infections, organ failure, and deaths have been reported.
To date FDA has not approved any regenerative medicine (stem cell) therapy for chronic pain, orthopedic conditions, neurological disorders, heart or lung diseases or Covid-19.