What is Cell Therapy?
Cell therapy (also called cellular therapy or cytotherapy) is therapy in which cellular material is injected into a patient; this generally means intact, living cells. Cell therapy is the subject of intense research and the basis of potential therapeutic benefit. Autologous cell therapy, where the donor and the recipient of the stem cells is the same person, is distinguished from allogenic cell therapy where the donor is a different person to the recipient of the cells. In pharmaceutical manufacturing, the allogenic methodology is promising because unmatched allogenic therapies can form the basis of “off the shelf” products. Cell therapy is targeted at many clinical indications in multiple organs and by several modes of cell delivery. Accordingly, the specific mechanisms of action involved in the therapies are wide ranging. Some of the cells used in cell therapy include stem , T, dendritic, natural killer, genetically modified, plasma, and red blood cells.
Gene therapy is an evolving field of cell therapy in which faulty genes are corrected in cells. Genes control heredity and provide the basic biological code for determining a cell’s specific functions. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace a defective gene. In gene therapy, the healthy copy of a defective gene is packaged within a vector, a biological delivery mechanism which is used to transport the genetic information into the diseased cells within the body. Once the gene is delivered into the correct cell, a therapeutic protein is naturally made by the cell from the therapeutic gene.
How do Cellular Therapies Work?
Cellular therapies use cells instead of donor organs, which are limited in supply. Researchers grow stem cells in a lab. These stem cells are manipulated to specialize into specific types of cells, such as heart muscle cells, blood cells or nerve cells. The specialized cells can then be implanted into a person. For example, if the person has heart disease, the cells could be injected into the heart muscle. The healthy transplanted heart cells could then contribute to repairing defective heart muscle. Researchers have already shown that adult bone marrow cells guided to become heart-like cells can repair heart tissue in people, and more research is ongoing.
What are Stem Cells?
Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.
What are Adult Stem Cells?
There are two primary types of stem cells, embryonic and adult stem cells. As the name suggests, the controversial embryonic stem cell are derived from embryos and are often developed from in vitro fertilized eggs, then donated to labs for research and therapy development. A previously overlooked alternative source for therapeutic stem cells resides within our own bodies, known as adult stem cells.
The adult stem cell is an undifferentiated cell that is found in a differentiated tissue. It has the ability to renew itself and become specialized to yield all the cell types of the tissue from which it originated and, in the appropriate environment, can also become a specialized cell of a different tissue. Adult stem cells are capable of self-renewal for the lifetime of the organism.
Sources of adult stem cells have been found in bone marrow, the blood stream, cornea and retina of the eye, the dental pulp of the tooth, liver, skin, gastrointestinal tract, adipose tissue and pancreas. Stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions and disabilities. Adult stem cells are relatively quiescent cells, particularly in organisms where cell turnover is low, yet they can mount a rapid and strong response to tissue stress and injury.
As cells designed to withstand crisis and orchestrate repair, stem cells must be especially resilient. Until recently, it had been thought that a stem cell collected from the bone marrow or peripheral blood (a hematopoietic stem cell) could not give rise to cells of a different tissue type, such as nerve cells. A number of clinical studies over recent years have affirmed the phenomenon known as plasticity. Plasticity is the ability of adult stem cells to differentiate to other cell types from a specific cell line. In other words, stem cells, from the bone marrow or from the circulating blood do have the ability to differentiate into other cell types such as heart cells or nerve cells.
Because of this plasticity, your own adult stem cells are the perfect ethical and moral alternative to stem cells derived from other donors or from embryonic stem cells. Adult stem cell transplants (bone marrow transplants) have been used for over 40 years in successfully treating cancers such as leukemia, multiple myeloma and lymphomas and it has now opened the doors of regenerative and reparative therapeutics.
For more information visit the United States National Institutes of Health online resource for stem cell research – http://stemcells.nih.gov/info/basics/
What is Personalized Medicine?
Personalized medicine is a medical model that proposes the customization of healthcare. In this model diagnostic testing is used to determine optimal therapies based on cellular analysis and genetic content of the patient. Medical treatments are then tailored to the individual patient.
What is Car-T Cell Therapy?
One approach to immunotherapy involves engineering patients’ own immune cells to recognize and attack their tumors. And although this approach, called adoptive cell transfer (ACT), has been restricted to small clinical trials so far, treatments using these engineered immune cells have generated some remarkable responses in patients with advanced cancer.
ACT’s building blocks are T cells, a type of immune cell collected from the patient’s own blood. After collection, the T cells are genetically engineered to produce special receptors on their surface called chimeric antigen receptors (CARs). CARs are proteins that allow the T cells to recognize a specific protein (antigen) on tumor cells. These engineered CAR T cells are then grown in the laboratory until they number in the billions.
The expanded population of CAR T cells is then infused into the patient. After the infusion, if all goes as planned, the T cells multiply in the patient’s body and, with guidance from their engineered receptor, recognize and kill cancer cells that harbor the antigen on their surfaces.
What is NK (Natural Killer) Cell Therapy?
When NK cells respond to the antibodies bound to cancer antigens on the surface of cancer cells, NK cells are activated and attack cancer cells.
The cancer cells that survive make themselves invisible to the T cells instructed to attack them (CTLs: cytotoxic T lymphocytes) by changing themselves over time in order to avoid their attack (MHC class I molecules disappear). NK cells are considered to attack such cancer cells rather effectively. On the other hand, NK cells are known to be less likely to attack cancer cells with MHC class I molecules, but this weak point can be overcome by enhancing the cancer-killing molecules in NK cells.
How Does NK Therapy Work?
In NK cell therapy, lymphocytes (including NK cells) are collected from patients’ blood. NK cells play a role in attacking abnormal cells such as cancer cells. Once harvested, the NK cells are cultured and grown in large amounts in order to further enhance their ability to kill cancer cells. The NK cells are then returned to patients’ bodies in order to strengthen their immunity.
What are some of the mechanisms by which cell therapy works?
- Therapeutic Vaccines
- Adoptive T Cell Therapies
- Monoclonal Antibodies
- Checkpoint Inhibitors or Blockade Therapy