Stem cell therapy for macular degeneration is the use of stem cells to heal, replace dead or damaged cells of the macula in the retina. Stem cell based therapies using bone marrow stem cells as well as retinal pigment epithelial transplantation are being studied. [1] A number of trials have occurred in humans with encouraging results. [2] [3]
In 1959, the first fetal retinal transplant into the anterior chamber of the eyes of animals was reported. Cell culture experiments on RPE were carried out in 1980. Cultured human RPE cells were transplanted into the eyes of animals, first with open techniques and methods and later with closed cavity vitrectomy techniques. [1]
In 1991, Gholam Peyman transplanted RPE (Retinal Pigment Epithelium) in humans but with limited success rate. Later, allogenic fetal RPE cell transplantation was tried in which immune rejection of the graft was a major problem. It has also been observed that the rejection rates were lower in dry AMD than that in wet AMD. Autologous RPE transplantation is conventionally done employing two techniques, namely, RPE suspension and autologous full-thickness RPE-choroid transplantation. Encouraging clinical outcomes has already been reported with the transplantation of the autologous RPE choroid from the periphery of the eye to a disease affected portion. [4]
Since 2003, researchers have successfully transplanted corneal stem cells into damaged eyes to restore vision. "Sheets of retinal cells used by the team are harvested from aborted fetuses, which some people find objectionable." When these sheets are transplanted over the damaged cornea, the stem cells stimulate renewed repair, eventually restore vision. [5] The such development was in June 2005, when researchers at the Queen Victoria Hospital of Sussex, England were able to restore the sight of forty people using the same technique. The group, led by Sheraz Daya, was able to successfully use adult stem cells obtained from the patient, a relative, or even a cadaver. [6]
In September 2014, the team of surgeons from Riken Institute's Center for Developmental Biology in Kobe, (Japan), led by Masayo Takahashi succeeded in a world-first transplanting of cells made from induced pluripotent stem cells into a human body. The operation was conducted as a clinical study and involved creating a retinal sheet from iPS cells, which were developed by Shinya Yamanaka. iPS cells are created by removing mature cells from an individual and reprogramming these cells back to an embryonic state. The retinal sheet was transplanted into a female patient in her 70s with age related macular degeneration (AMD), an eye complication that blurs the central field of vision and can progress into blindness. The iPS cells were hoped to stop the progression of AMD. The team used iPS cells made from the patient's own skin cells. Then in March 2017 team carried out the world's first successful transplant of retinal cells created from donor iPS cells into the eye of a patient with advanced wet age-related macular degeneration. [7] Time and cost used in the surgery has been significantly reduced by using super donor cells, cells derived from people with special white blood cell types that aren't rejected by the immune systems of receiving patients. During the surgery the patient received a transplant of approximately 250,000 retinal pigment epithelial cells into the eye generated from donor-derived iPSCs. Results of this landmark study were published in the New England Journal of Medicine. [8]
Scanning laser ophthalmoscopy (SLO) is a method of examination of the eye. It uses the technique of confocal laser scanning microscopy for diagnostic imaging of the retina or cornea of the human eye.
Macular degeneration, also known as age-related macular degeneration, is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, some people experience a gradual worsening of vision that may affect one or both eyes. While it does not result in complete blindness, loss of central vision can make it hard to recognize faces, drive, read, or perform other activities of daily life. Visual hallucinations may also occur.
Bruch's membrane or lamina vitrea is the innermost layer of the choroid of the eye. It is also called the vitreous lamina or Membrane vitriae, because of its glassy microscopic appearance. It is 2–4 μm thick.
A cone dystrophy is an inherited ocular disorder characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision.
Choroideremia is a rare, X-linked recessive form of hereditary retinal degeneration that affects roughly 1 in 50,000 males. The disease causes a gradual loss of vision, starting with childhood night blindness, followed by peripheral vision loss and progressing to loss of central vision later in life. Progression continues throughout the individual's life, but both the rate of change and the degree of visual loss are variable among those affected, even within the same family.
Drusen, from the German word for node or geode, are tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium of the eye. The presence of a few small ("hard") drusen is normal with advancing age, and most people over 40 have some hard drusen. However, the presence of larger and more numerous drusen in the macula is a common early sign of age-related macular degeneration (AMD).
The pigmented layer of retina or retinal pigment epithelium (RPE) is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells.
Stargardt disease is the most common inherited single-gene retinal disease. In terms of the first description of the disease, it follows an autosomal recessive inheritance pattern, which has been later linked to bi-allelic ABCA4 gene variants (STGD1). However, there are Stargardt-like diseases with mimicking phenotypes that are referred to as STGD3 and STGD4, and have a autosomal dominant inheritance due to defects with ELOVL4 or PROM1 genes, respectively. It is characterized by macular degeneration that begins in childhood, adolescence or adulthood, resulting in progressive loss of vision.
Astellas Institute for Regenerative Medicine is a subsidiary of Astellas Pharma located in Marlborough, Massachusetts, US, developing stem cell therapies with a focus on diseases that cause blindness. It was formed in 1994 as a company named Advanced Cell Technology, Incorporated (ACT), which was renamed to Ocata Therapeutics in November 2014. In February 2016 Ocata was acquired by Astellas for $379 million USD.
Choroidal neovascularization (CNV) is the creation of new blood vessels in the choroid layer of the eye. Choroidal neovascularization is a common cause of neovascular degenerative maculopathy commonly exacerbated by extreme myopia, malignant myopic degeneration, or age-related developments.
Intraocular hemorrhage is bleeding inside the eye. Bleeding can occur from any structure of the eye where there is vasculature or blood flow, including the anterior chamber, vitreous cavity, retina, choroid, suprachoroidal space, or optic disc.
Retinal gene therapy holds a promise in treating different forms of non-inherited and inherited blindness.
The Food and Drug Administration (FDA) approved the first clinical trial in the United States involving human embryonic stem cells on January 23, 2009. Geron Corporation, a biotechnology firm located in Menlo Park, California, originally planned to enroll ten patients with spinal cord injuries to participate in the trial. The company hoped that GRNOPC1, a product derived from human embryonic stem cells, would stimulate nerve growth in patients with debilitating damage to the spinal cord. The trial began in 2010 after being delayed by the FDA because cysts were found on mice injected with these cells, and safety concerns were raised.
Lineage Cell Therapeutics, Inc. is a clinical-stage biotechnology company developing novel cell therapies for unmet medical needs. Lineage’s programs are based on its robust proprietary cell-based therapy platform and associated in-house development and manufacturing capabilities. With this platform Lineage develops and manufactures specialized, terminally differentiated human cells from its pluripotent and progenitor cell starting materials. These differentiated cells are developed to either replace or support cells that are dysfunctional or absent due to degenerative disease or traumatic injury or administered as a means of helping the body mount an effective immune response to cancer.
Anti–vascular endothelial growth factor therapy, also known as anti-VEGF therapy or medication, is the use of medications that block vascular endothelial growth factor. This is done in the treatment of certain cancers and in age-related macular degeneration. They can involve monoclonal antibodies such as bevacizumab, antibody derivatives such as ranibizumab (Lucentis), or orally-available small molecules that inhibit the tyrosine kinases stimulated by VEGF: sunitinib, sorafenib, axitinib, and pazopanib.
Emixustat is a small molecule notable for its establishment of a new class of compounds known as visual cycle modulators (VCMs). Formulated as the hydrochloride salt, emixustat hydrochloride, it is the first synthetic medicinal compound shown to affect retinal disease processes when taken by mouth. Emixustat was invented by the British-American chemist, Ian L. Scott, and is currently in Phase 3 trials for dry, age-related macular degeneration (AMD).
Robert E. MacLaren FMedSci FRCOphth FRCS FACS VR is a British ophthalmologist who has led pioneering work in the treatment of blindness caused by diseases of the retina. He is Professor of Ophthalmology at the University of Oxford and Honorary Professor of Ophthalmology at the UCL Institute of Ophthalmology. He is a Consultant Ophthalmologist at the Oxford Eye Hospital. He is also an Honorary Consultant Vitreo-retinal Surgeon at the Moorfields Eye Hospital. MacLaren is an NIHR Senior Investigator, or lead researcher, for the speciality of Ophthalmology. In addition, he is a member of the research committee of Euretina: the European Society of Retina specialists, Fellow of Merton College, in Oxford and a Fellow of the Higher Education Academy.
Geographic atrophy (GA), also known as atrophic age-related macular degeneration (AMD) or advanced dry AMD, is an advanced form of age-related macular degeneration that can result in the progressive and irreversible loss of retinal tissue (photoreceptors, retinal pigment epithelium, choriocapillaris) which can lead to a loss of visual function over time. It is estimated that GA affects over 5 million people worldwide and approximately 1 million patients in the US, which is similar to the prevalence of neovascular (wet) AMD, the other advanced form of the disease.
Masayo Takahashi is a Japanese medical physician, ophthalmologist and stem cell researcher.
Conbercept, sold under the commercial name Lumitin, is a novel vascular endothelial growth factor (VEGF) inhibitor used to treat neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME). The anti-VEGF was approved for the treatment of neovascular AMD by the China State FDA (CFDA) in December 2013. As of December 2020, conbercept is undergoing phase III clinical trials through the U.S. Food and Drug Administration’s PANDA-1 and PANDA-2 development programs.