RIH Hopes to Speed Vision Recovery Time Using Stem Cells

May 09, 2011

Our challenge is to find a way of encouraging adipose-derived stem cells to differentiate into two different kinds of retinal cells and potentially use these to improve outcomes in our retinal transplant surgeries.

It is difficult to open a newspaper or magazine these days without seeing an article about stem cell research. There is a great deal of excitement surrounding these amazing cells that seem to have unlimited potential to help treat many different diseases. Most of the excitement centers on scientific research in this field.

There is a great deal of hope from both patients and researchers that potential new therapies for restoring vision will be available in the not-so-distant future. Against this scientific and political backdrop, let us explore briefly the different types of stem cells that are currently being investigated and how these might help treat diseases of the retina.

Basically, there are two types of stem cells.1 The first, embryonic stem cells, are the cells that have created so much ethical debate. These cells typically come from embryos created by in vitro fertilization, or IVF, which uses human eggs and sperm that are combined outside of the body in a laboratory in order to produce fertilized eggs that can then be put into the mother’s womb. In order to increase the chances of success, these fertilized eggs are typically produced in sufficient numbers to allow an extra supply that can be frozen for later use. As a result of this process, there are leftover embryos like these in just about every location that does IVF. Scientists can use these leftover fertilized eggs to extract an inner core of cells that can multiply indefinitely. These embryonic stem cells can theoretically be induced to develop into any of the 200 different types of human tissue.

The second type of stem cell is called the adult stem cell. As the name implies, adult stem cells exist naturally in the adult human body. They can be taken from various tissues that regenerate themselves on a regular basis. This includes such tissues as the blood, bones, skin and lining of the gut. They have also been found in other seemingly unlikely places such as thebrain and fat tissue. There are no ethical considerations involved with the use of adult stem cells because human embryos are not required. They can be removed from and used in the same patient, in which case there is no need for any kind of therapy to prevent the patient from rejecting tissue, as is usually needed with the use of tissue from a different person.

Researchers at the University of Washington in Seattle have been able to develop a highly successful method to coax human embryonic stem cells into becoming retina cells. These then further develop into functioning photoreceptor cells after being transplanted into a living mouse model.2 Whether this can be done in humans is yet to be seen. However, progress in this field is certainly very encouraging for patients with degenerative eye conditions leading to severe visual loss, such as macular degeneration and retinitis pigmentosa.

Here at RIH, efforts are currently under way to make adipose-derived stem cell therapy available to a select group of macular degeneration patients in Hawaii. This project is being conducted in conjunction with a local stem cell biotech company that has developed its own method for harvesting adult adipose stem cells from patients and using these cells for a variety of stem cell based interventions. Our plan is to use this technology in combination with Retinal Pigment Epithelium (RPE) transplant surgery, a procedure that Dr. Michael Bennett has been performing for the past decade. The basic idea of this surgery is to take functioning RPE from an area of healthy retina and slip it underneath the area of retina that is being affected by macular degeneration. Dr. Bennett has been performing this intricate surgery with growing success as the technology and instrumentation for this procedure continue to evolve. Early RPE transplant surgeries used to take upwards of one and a half to two hours to perform and the collateral damage that occurs for that duration of a retinal surgical case, regardless of the complexity, was simply unacceptable. Our typical transplant surgery is now performed in a fraction of the original time. Now, RIH is poised to take this therapy to an entirely new level.

What we envision is a two-step process. First, patients undergo a small, outpatient liposuction procedure during which stem cells from the patient’s own extra fat are harvested and prepared for use in retina surgery. These stem cells can be kept viable for several weeks, which would allow for convenient scheduling of a second outpatient procedure, during which the patient’s own stem cells would be injected underneath the retina along with the patient’s own RPE transplant. Initial results from RPE transplants alone have already indicated that patients are noticing steady improvement in the quality of their central vision following surgery, and our hope is that using adult stem cells in combination will increase the viability of the transplant and lead to additional improvement in vision. RIH is the only research center currently undertaking this kind of research and we expect that a pilot study involving macular degeneration patients will be starting up within the next few months.

But this kind of therapy is not limited to treating macular degeneration. Our goal is to further develop this adjuvant cellular therapy for other vision threatening conditions, like macular holes, epiretinal membranes, retinal detachments, vascular occlusions and hereditary conditions like retinitis pigmentosa

by: Clifton S. Otto, MD

References: 1. http://dels.nas.edu/bls/stemcells/basics.shtml 2. Lamba, D. A. et al. Cell Stem Cell 2009;4(1):73–79.

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