As I mentioned in my last post, this post will be about the stem cells that could be used to treat ALS. There are several types of stem cells that could be used to treat ALS but in this post I will be talking about the following types:
- Embryonic stem cells
- Induced pluripotent stem cells
- Mesenchymal stem cells
- Neural stem cells
Embryonic stem cells and induced pluripotent stem cells are pluripotent, which means that they can be developed into any type of cell, and can be injected into the spinal cord to become motor neurons. The main problem with using these types of stem cells is that nobody knows how to make them regrow and reconnect to the muscles to restore function. Another problem with using embryonic stem cells is that their use is controversial as the stem cells are taken from aborted fetuses, which are viable and have the potential to create new life. To avoid this problem, induced pluripotent stem cells are being used as a replacement for embryonic stem cells. These cells begin as adult cells that are reprogrammed to act like embryonic stem cells by injecting DNA/transcription factors into the cells. The DNA/transcription factors would then change the state of the chromosomes. However, some people say that induced pluripotent stem cells can still cause ethical issues as induced pluripotent stem cells can also contribute to a human embryo.
Mesenchymal stem cells derived from the bone marrow are said to be able to treat ALS when they are injected into the bloodstream. This is because the stem cells provide support for cells by releasing growth factors but no studies have shown that they replace neurons/astrocytes in the central nervous system. Neural stem cells can be used to make astrocytes, cells that support motor neurons, and to alter these astrocytes to make extra growth factors, which make the neurons remain healthy and grow.
Several clinical trials have been conducted and lots of clinical trials are currently being carried out to find out whether the different types of stem cells could be used as a cure for ALS. Most of these are in the early stages (phase 1 or phase 2) and are conducted to find out what the frequent and serious side effects are and the safety and efficacy of using these stem cells in stem cell therapy.
Can stem cells be used in the future to treat ALS in the future? I believe they can be used to treat ALS as the results of most clinical trials using stem cells show that stem cells can be used to treat ALS. Also, the ethical problems caused by the use of embryonic stem cells can be avoided as there are other types of stem cells (e.g. neural stem cells) that can be used instead. However, it will take a long time before stem cells can realistically be used to treat ALS as there are still many hurdles to overcome (e.g. getting the implanted stem cells to grow from the spinal cord out to the muscles).
References (this post and my last post):
- Gillian Pocock, Christopher D. Richards, David A. Richards, Human Physiology, 4th ed. (Oxford, 2013) p. 55