In the last post, we identified the Retinal Pigment Epithelium as the layer in the retina that becomes diseased in macular degeneration. The cells, once damaged, do not have the ability to divide, regenerate or regrow. Thus, permanent damage (i.e. loss of vision) ensues.
By The Way. There are two basic types of stem cells; embryonic stem cells and adult (or somatic) stem cells. While there are differences between the two, I am collectively referring to both types as “stem cells” to simply highlight the uniqueness of stem cell research.
Stem Cells are Highly Clone-able. Stem cells have the potential to replicate endlessly, and therefore, represent an infinite source of “supply.” Right now, stem cells can be cultured, or grown, in the laboratory. Millions of cells can be cultured from just one line of stem cells. Scientists have, to date, been successful transplanting corneas, hearts, lungs, the pancreas, etc., but there is always a severe shortage of donors. Far too few people receive needed, possibly life-saving, organ transplants due to short supply. In theory, stem cell therapy could potentially alleviate the “supply” issues.
Stem cells can become specialized. A single stem cell has no particular function. It is has the potential; however, to differentiate, or change, into any type of cell in the body. Stem cells can become heart cells, muscle cells, pancreas cells, etc………………and, Retinal Pigment Epithelium (RPE) cells. Stem cells are “pluripotential” (a cell that can transform into any specialized cell).
How will this cure Macular Degneration? In theory, stem cells can be grown in the laboratory and then “turned into” RPE cells. The RPE cells can then be inserted, or transplanted, underneath the retina. Alternatively, it may also be possible to transplant less specialized cells into a particular tissue, in this case, the retina, and allow the stem cells to become specialized (turned into) Retinal Pigment Epithelium cells after insertion/transplantation underneath the retina.
In theory, stem cells offer the potential be a renewable and infinite source of tissue. Stem cells offer the potential to replace sick, damage RPE cells with healthy tissue. Present therapies, e.g. diets and vitamins, are focused at nourishing diseased tissue, whereas stem cell research offers the potential of “remove and replace.”
Last Post: Part 1: Introduction to Stem Cells and Retinal Disease
Next Post – Obstacles to Stem Cell Therapy
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist