Stem Cell Therapies for Diseases of Aging: Long-Awaited Trials in the Eye.

By, Rob O’Brien and Karen Ring.

One general facet of aging is a loss of the body’s ability to robustly repair itself or regenerate lost tissue. Diseases such as Alzheimer’s, diabetes, and stroke are all associated with loss of particular tissues and cell types over time. While we have been able to treat some diseases using tissue or organ transplants, there are substantial limitations to the supply and utility of these donor tissues. Human embryonic stem cells (ESCs) isolated in the late 90’s and human induced pluripotent stem cells (iPSCs) discovered in 2007 provide exciting alternatives for tissue replacement therapies. Both ESCs and iPSCs are pluripotent and can be coaxed into any cell type within the body, thus offering an endless source of transplantable tissue to treat many different diseases. While promising, there are still many logistical hurdles associated with both ESCs and iPSCs that have limited their potential to mature into real therapies.

A look inside of an eye with AMD.

The inside of an eye with AMD.

However, in the past few weeks studies using ESCs and iPSCs in human patients for several diseases were announced and results were published showing safety and some indication of effectiveness of ESCs in treating two age-related vision diseases known as age related macular degeneration (AMD) and Stargardt’s macular dystrophy. Both diseases are caused by loss of cells from part of the retina of the eye and result in partial or total blindness.

Human ESC-derived retinal pigment epithelium in patients with AMD and Stargardt’s macular dystrophy.

Dr. Robert Lanza and his group recently conducted a clinical trial using retinal pigment epithelial cells derived from human ESCs in 18 patients with either AMD or Stargardt’s macular dystrophy. This trial’s original purpose was to demonstrate that injection of retinal cells derived from ESCs is safe in humans. Despite the early stage of the clinical trial, the study found evidence that almost half of the patients had improved eyesight after treatment. These initial results must be tested in larger groups with placebo/sham controls before they will be available outside of clinical trials, however they represent a major step forward in regenerative medicine and represent hope for improved quality of life for patients with degenerative eye diseases.

For more on this exciting clinical trial, read Dr. Lanza’s publication in the Lancet.

Retinal tissue derived from human iPSCs for treatment of eye disease.

Retinal Pigment Epithelial cells derived from patient induced pluripotent stem cells. (RIKEN)

Retinal pigment epithelial cells derived from patient iPSCs. (RIKEN)

A group at RIKEN center in Japan led by Dr. Masayo Takahashi began clinical studies earlier this year using retinal epithelium cells derived from human iPSCs to treat patients with AMD, a disease that is the most common cause of vision impairment in people over the age of 50. Takahashi’s group was able to derive retinal tissue from iPSCs generated from patient skin cells. In September, they transplanted a small sheet of retinal tissue into the eye of a 70-year old woman who suffers from AMD. The transplant was successful, and so far the new retinal tissue has survived and not caused any tumors in the patient. The efficacy of the transplant has not been reported, but the group did indicate any improvement would be modest as the patient had a very advanced form of AMD. Takahashi’s team plans to conduct additional transplants in other patients while continuing to monitor the safety and efficacy of their iPSC therapy.

For more on the technology Dr. Takahashi used to generate retinal tissue from human iPSCs, read her group’s published report in Stem Cell Reports.