Organ and Tissue Donation: Medical Advances and Impact
Organ Transplantation: A Modern Medical Success
Organ transplantation is one of the great successes of this century. The first successful kidney transplant was performed in 1954. Christiaan Barnard successfully transplanted the first heart in 1967. This therapy has improved the lives of many sick people.
Who Can Donate?
Transplantation is a highly developed medical technique that works very well in recipients. It allows them to save their lives or improve their quality of life, but this requires a donor.
The donor may be a person in a situation of brain death, i.e., a person whose brain has stopped working, but whose heartbeat is maintained artificially so that the organs to be transplanted will be in good condition. In some types of transplants, the person may be alive.
Spanish Legislation on Organ Donation
The law governing organ donation and transplantation states:
- Establishment of brain death.
- Respect for the will of the deceased regarding organ donation or not.
- The need for the diagnosis of death to be made by a team of doctors.
- Altruism of the donation and not the marketing of organs.
- The guarantee of anonymity.
- The application of medical criteria for the distribution of donors.
Challenges in Organ Transplantation
Transplantation to replace a diseased organ that endangers a person’s life with another that works. Organ and tissue transplantation as a therapeutic method has 3 major problems:
Immune Rejection
If white blood cells immediately detect something strange, they try to destroy it. Therefore, it is essential that the donor and receiver are as close as possible to be compatible; otherwise, there would be a rejection. To avoid rejection, powerful immunosuppressant drugs are used that dramatically reduce the responsiveness of the immune system. Immunosuppressants, while reducing the possibility of rejection, leave the body exposed to various infections.
Shortage of Organs
Spain is the country with the highest rate of donors. Yet, about 5,000 patients are on waiting lists.
Technical Impossibility of Obtaining Certain Organs
Some organs are impossible to obtain and transplant. Scientists have put their efforts into developing new therapies that eliminate the problem of the shortage of organs and tissues.
These new therapies in the near future will involve regenerative medicine, which relies on the use of stem cells to regenerate any tissue that does not work without causing any damage.
Human Reproduction
The Role of Stem Cells
Stem cells play a crucial role in the process leading to the formation of an individual. This process begins with the formation of a cell, the zygote, and includes:
- Fertilization: The union of egg and sperm that occurs inside the female genital tract, specifically in the fallopian tubes. The result is the formation of the zygote. The fallopian tube connects the ovary to the uterus.
- Development: The set of changes that occur in any living being throughout their lives. The first part of development ends when prenatal. Postnatal development begins at birth.
Stages of Embryonic Development
If a sperm meets an egg in the fallopian tube, it tries to cross the membrane. If it succeeds, the egg produces a hard coating and prevents a second sperm from penetrating.
The zygote, formed by a single cell, continues to move through the fallopian tube. On its way to the uterus, it begins to divide. On the second day, it consists of two cells that are kept together.
The cells continue to divide to form an embryo of 32 cells called a morula because of its appearance.
A cavity is formed inside the morula, which takes the form of a hollow ball. This is called an early blastocyst.
A group of cells condenses inside the blastocyst and forms a solid, known as the late blastocyst.
The embryo nests in the wall of the uterus, which has been prepared for this event by covering a layer called the endometrium.
Assisted Human Reproduction
The causes of infertility in couples are numerous, and sometimes the reason is unknown. To overcome the inability to have children, there are assisted reproduction techniques:
- Artificial Insemination: The easiest method is to introduce sperm artificially inside the female genital tract.
- In Vitro Fertilization and Embryo Transfer (IVF-ET): Fertilizing an egg with a sperm outside the woman’s body. This technique is used when the female genital tract is blocked by the abnormal proliferation of tissue. The technique is developed in stages:
- Obtaining Eggs: Using a hormonal treatment, the production of eggs in the ovaries of women is stimulated. This is done to mature between 5 and 10 eggs in one cycle.
- Fertilization: Ova are fertilized by sperm in a test tube in the laboratory. The embryos developed in vitro are left for a few days until they reach the morula stage.
- Embryo Transfer: The embryos are inserted into the uterus of the woman.
Stem Cells and Regenerative Medicine
The zygote is a cell that has the potential to develop a complete individual. This cell divides again and again, giving rise to new cells that differentiate and eventually specialize, gradually acquiring a fixed form and function.
A stem cell is used to refer to unspecialized cells that are capable of:
- Multiplying and causing long unspecialized cells.
- Causing cells to differentiate and give rise to specialized cells.
Types of Stem Cells
- Totipotent: Cells capable of generating a complete individual.
- Pluripotent: They cannot cause a complete individual but retain the ability to create each and every one of the cell types that comprise it.
- Multipotent: Some cells retain some capacity to create some types of cells; these are adult stem cells, such as red blood cells and platelets.
- Oligopotent: Some adult stem cells can produce only a few types of cells, such as skin or nerve tissue.
Regenerative Medicine
This new biomedical branch aims to produce a tissue or organ to replace the affected one. Stem cells could be used as:
- Embryonic Stem Cells: These have the most potential because they are pluripotent and can create any type of tissue.
- Adult Stem Cells (Tissues): Found in all human tissues.
- Induced Pluripotent Stem Cells (iPSCs): These are under investigation after being subjected to treatment to become pluripotent embryonic stem cells.
Cloning
Cloning is a process by which an identical copy, from a genetic standpoint, is obtained from any living entity, such as the cell of an organism.
How to Clone an Animal
In 1996 in Scotland, the sheep Dolly was born, the first cloned mammal in history. The technique is called nuclear transfer.
Nuclear Transfer
- A differentiated cell is obtained from the individual who wants to be cloned.
- An egg is extracted from a female donor.
- The egg nucleus is removed.
- The nucleus of the differentiated cell is transferred to the egg without a nucleus.
- The cell is grown in the laboratory in a special medium.
- When it reaches the morula stage, it is transferred to the uterus of the recipient mother.
- After the gestation period, a clone is born.