Unless you've been hiding under a rock and have no interest in medical advances, you have probably heard, read about, or seen television coverage of stem cells and their increasing use in medicine.
There are five major types of stem cells (SCs):
1. Embryonic: these are culled from the blastocyst phase of embryonic growth (a blastocyst is the 16-20 cell mass that is present soon after fertilization).
2. Umbilical cord blood SCs: these stem cells are harvested from- you guessed it- umbilical cord blood.
3. Induced pluripotential: these are adult cells whose nucleus has incorporated embryonic genes so that they behave like embryonic SCs.
4. Allogeneic: these are SCs obtained from healthy donors.
5. Autologous: these SCs are a patient's own stem cells
In an embryo,Best Movies of the Decade, SCs can differentiate into all of the specialized organs that will eventually be needed for life. In adults, SCs serve as a repair system in that they maintain the normal turnover of various organ tissues.
So what is special about these cells? The first unique property is that they are capable of self-renewal, meaning they can divide and multiply and stay in a stem cell state, meaning they remain "blank slates."
The second special property is the ability to differentiate into different cell types. There is a distinction here since embryonic SCs are considered totipotent. They are truly able to become any cell type. This makes them different from adult SCs which are considered multipotent. That means they can become many different cell types but not all cell types.
So what are strengths and weaknesses of these different cell types? Basically, embryonic SCs are probably the ones that can be most useful in any given situation since they are totipotent. Weaknesses are primarily the ethical and religious concerns that have been raised about these. Also, is there a shutoff mechanism that prevents malignant transformation?
Induced pluripotential SCs may be promising but they don't behave exactly like embryonic SCs and rejection is a significant concern. The same goes for allogeneic (donor) SCs.
Adult autologous SCs,beijing erotic massage, often referred to as mesenchymal SCs, are interesting in that they are capable of significant repair. These are the cells that help you recover from injury and are currently of significant interest for the potential treatment of osteoarthritis. Since they come from the host,beijing massage service, rejection is a non-issue. The major problem is that there are still a number of unanswered questions. What exactly is their ability to differentiate? Do they require a scaffold in order to multiply? If so, which is the best scaffold for this purpose? Do they require additional growth factors to help induce and sustain multiplication and division? What is their useful life span?