Creating Cybrids to Study Age-Related Diseases

DEF Research Director Dr. M. Cristina Kenney’s research has shown that the mitochondrial DNA from different ethnic/racial populations may play a key role in determining that population’s resistance or susceptibility to disease (see previous article on 11/12/15 – Mitochondria and Age-Related Macular Degeneration). In order to study these effects, Kenney has developed the cybrid model using mitochondria from subjects of different ethnic/racial groups (Figure 1). The comparison of an individual’s mitochondria with that from other ethnic/racial groups (African, European, Asian or Ashkenazi Jewish) allows us to determine if their mitochondria determine that population’s susceptibility or resistance to disease and to response to drugs.

cybrids to study age-related disease
Figure 1 – Cybrids are cell lines with identical nuclei but the mitochondrial DNA from individuals of different ethnic/racial groups.

Personalized cybrids
Kenney’s cybrids are made with mitochondria from the blood taken from individual living donors. Looked at individually they are all really “personalized cybrids” because each cybrid test system has the mitochondria from the original donor and reflects the responses of that donor.

Using Cybrids to Study Age-Related Diseases

How is Kenney using these personalized cybrids?
Kenney is partnering with Dr. Pinchas Cohen, dean of the University of Southern California, Leonard Davis School of Gerontology, to explore how novel, small proteins produced from mitochondria might be used to treat a variety of age-related diseases such as age-related macular degeneration, Alzheimer’s, Parkinson’s, stroke and cholesterol. Cohen’s laboratory has discovered and characterized many of these new, small proteins called “mitochondrial derived peptides” (MDPs). His work has shown that these MDPs can protect brain cells from damage and early death, such as occurs in Alzheimer’s disease. Cohen and Kenney are now testing these MDPs in the K and H cybrids to assess their protective effects to stop retinal cell death, such as seen in AMD.

Kenney explains her approach:
“Our cybrid system represents a very powerful technique. We are now using the Ashkenazi Jewish population as an excellent model to learn how the mitochondria, with their unique mtDNA, influence the risk factors for AMD. We plan to extend the study to investigate Ashkenazi Jewish people’s susceptibility to Alzheimer’s disease, heart disease and stroke. Eventually, we believe the findings for the K haplogroup mitochondrial DNA will be applicable to other groups, as well.”

11/17/15

Anthony B. Nesburn, MD  FACSAnthony B. Nesburn, MD, FASC
President/Medical Director
Discovery Eye Foundation

What You Need to Know About Cataracts

6/5/14

Do you feel like your vision is getting worse? Do you feel like colors are not as vibrant as they used to be? Are you having more trouble with glare? If you have any of these symptoms, you may be experiencing the effects of cataracts.

Cataracts are a normal aging process of the crystalline lens in the eye. Well you may ask — what is the crystalline lens? It is easiest to think of the eye as a camera. The eye has a lens (actually two) – the cornea (the front window of the eye) and the crystalline lens (inside the eye). It also has an aperture (the colored iris), and film (the retina). All these structures work together to focus light and allow us to see – just like a camera. When we are young (less than 40), the crystalline lens is flexible. This is why we are able to see distance and then near without the need for reading glasses. The crystalline lens is able to change its shape depending on where one is looking.

Figure 1 – Slit-lamp photo of a visually significant cataract.
Figure 1 – Slit-lamp photo of a visually significant cataract.

As we age, the crystalline lens becomes less flexible, thereby causing one’s near vision to be more blurry. This necessitates the need for reading glasses. As the crystalline lens become less flexible with age, the lens also starts to become more yellow and can also become cloudy. When the yellowing and/or clouding become visually significant, we refer to this as a cataract (figure 1).

Are cataracts dangerous? The simple answer is no. In the vast majority of cases, a cataract can be monitored until it becomes visually significant (drop in vision, glare, decreased contrast, vision related difficulties with day to day activities, etc). However, there are a few instances in which cataract removal is a medical necessity. Routine examinations by your eyecare provider can help you determine if you are at risk for these less common instances.

Figure 2 – Intraoperative photo during cataract surgery (prior to cataract removal).
Figure 2 – Intraoperative photo during cataract surgery (prior to cataract removal).

What can I expect during cataract surgery? Do you have to replace the crystalline lens with anything? Cataract surgery involves removing the clouded crystalline lens (figure 2) and replacing it with an artificial lens known as an intraocular lens (IOL) (figure 3). Surgery generally takes 10-15 minutes under a mild sedative, and you don’t have to stop any of your current medications. Anesthesia is achieved with drops and you will only feel mild pressure during the surgery. IOLs come in different styles – Standard IOLs grossly correct your vision and you can fine tune your vision (distance and near) with glasses post-operatively;

Figure 3 – Intraoperative photo during cataract surgery (after implantation of an IOL).
Figure 3 – Intraoperative photo during cataract surgery (after implantation of an IOL).

Toric (astigmatism correcting) IOLs allow for increased spectacle independence, but glasses will still be needed for distance or near; Accommodating IOLs “flex” within the eye to decrease your dependence on distance and near glasses; Multifocal IOLs allow spectacle independence for distance and near. I always counsel patients that there is no perfect IOL and you have to determine which IOL is best for your particular situation. Your doctor can help you decide which IOL is best for you. Generally, cataract surgery is extremely safe. Your doctor will discuss particular risks specific to your eye.

How do I know if cataract surgery is right for me? The best way to know if you have a cataract and if it time to consider surgery is to consult with your local ophthalmologist. If you have experienced a recent drop in vision, that is not correctable with glasses, cataract surgery may be able to restore your vision!

Garg feb 2014 thumbSumit “Sam“ Garg, MD
Medical Director
Vice Chair of Clinical Ophthalmology
Assistant Professor of Ophthalmology
Gavin Herbert Eye Institute – UC, Irvine

Little Bottle, Big Relief

6/3/14

What you need to know about eye drops.

Have you been staring at a computer all day and your eyes are tired? Have allergies been making your eyes watery and itchy? Are your contact lenses irritating your eyes? If you have experienced any of these conditions, you have probably turned to eye drops for relief.

While eye drops are an easy and effective means of treating a number of eye issues, there are many different eye drops available, both over the counter (OTC) and by prescription. It is wise to know what your underlying condition is before trying to get relief.
eye drops 6.3.14
If your eyes are red and you may want to try a decongestant eye drop, which will shrink the tiny blood vessels in the “whites” of your eyes (sclera), but they also cause dryness so may not be a good choice if you wear contact lenses.
For lens wearers you are better off with a re-wetting drop to lubricate the eye and lens making you more comfortable. Another problem with the decongestant eye drops is over use – which can cause irritation and an increased tolerance that could lead to more redness.

If you suffer from allergies and antihistamine eye drop would be the best choice for relief from itchy, watery, red and swollen eyes. They work by reducing histamine in the eye tissue.

Lubricating eye drops, also known as artificial tears, are for short-term relief caused by temporary situations such as eye strain form computer use, being tired or being outdoors in windy and/or sunny conditions. If the condition is chronic, a prescription eye drop will be the best choice.

It is important to remember that if any of the above symptoms worsen or continue for an extended period of time, it is time to see your eye doctor to determine the underlying cause of your issue and to rule out eye disease. Postponing a visit could also lead to an eye infection.

Prescription drops are used to treat a wide variety of eye diseases such as glaucoma, dry eye and the symptoms of ocular herpes. They are also used to help with healing from cataract surgery, corneal transplants, glaucoma surgery and even Lasik. it is extremely important to use them as often as your ophthalmologist recommends to improve healing and prevent infection.

Because of the ease of applying eye drops researchers are working toward using them to treat other eye diseases. Ocular herpes symptoms are sometimes treated with antiviral and steroid drops. But this only is targeted at the symptoms and not the underlying cause, the herpes simplex virus. Lbachir BenMohamed, PhD and Steven Wechsler, PhD at the University of California, Irvine, Gavin Herbert Eye Instittue have been working to determine what reactivate the herpes simplex virus and develop an eye drop that would either stop the reactivation of the virus or kill it.

Using eye drops to treat age-related macular degeneration (AMD) is also being explored. Researchers at the Institute of Ophthalmology at University College London are working with nanoparticles to deliver anti-VEGF drugs such as Lucentis and Avasitn to the back of the eye via drops. “The study shows that Avastin can be transported across the cells of the cornea into the back of the eye, where is stops blood vessels from leaking and forming new blood vessels, the basis for wet AMD.” While researchers in the Department of Ophthalmology, Tufts University School of Medicine in Boston “reported in their “proof of concept” study that topical application of a compound called PPADS inhibits damage to the tissues in the eye that impacts the individual’s ability to see color and fine detail, as well as reduces the growth of extraneous blood vessels in the back of the eye related to AMD.” It would work in both dry and wet AMD reduce the need for direct injections.

Eye drops, when properly applied, can provide temporary relief from symptoms of eye discomfort. But if the symptoms worsen or continue for an extended period of time, consult your eye doctor. To make sure you apply the eye drops correctly check out the article in our February 2013 newsletter for 12 easy steps to get the drops into your eyes and avoid infection.

One final note – keep your eye drops out of reach of children. Eye drops come in small bottles that are the perfect size for small hands and don’t have the same security tops found on other medications. The FDA has warned that ingredients found in some eye drops that relieve redness have caused abnormal heart rate, decreased breathing, sleepiness, vomiting and even comas in children five and younger that have ingested them. If you child has swallowed eye drops, call the Poison Help Line 800-222-1222.

Susan DeRemerSusan DeRemer
Vice President of Development
Discovery Eye Foundation

New Hope for Corneal Scarring

5/22/14

There are several etiologies for limbal stem cell deficiency of the front of the eye. These include chemical and thermal burns, Steven-Johnson syndrome (which is an autoimmune severe allergic reaction that causes a burn from within), congenital aniridia, and a few other insults such as contact lens over-wear. All of these cause severe ocular surface scarring and problems with the cornea. Many eyes with these diseases have problems with corneal healing. They do not have the stem cells to support ocular surface health. The scarring can be so severe in many cases that severe corneal blindness can result.

Limbal stem cells from the human cornea, with a protein known as p63 stained yellow. Cell nuclei (which hold the DNA) are stained red.  From eurostemcell.org
Limbal stem cells from the human cornea, with a protein known as p63 stained yellow. Cell nuclei (which hold the DNA) are stained red. From eurostemcell.org

In these cases, a simple corneal transplant will quickly fail and not result in any visual improvement. The reason for this is that the stem cells of the ocular surface have been damaged or burned out.

Visual rehabilitation for these eyes usually requires a limbal-corneal stem cell transplantation. The stem cells can be taken from the other healthy eye of the same patient, a living related donor, and or cadaveric tissue. In most cases systemic immunosuppression medications need to be taken for 1 to 3 years following surgery in order to minimize risk of rejection. Management of these patients is done in conjunction with an immunologist or a transplant specialist who can co-manage and monitor for systemic toxicity while the patient is on the these immunosuppressive medications. As most of these eyes also have concomitant glaucoma and scarring of the eyelids to the globe, co-management with a glaucoma specialist and an oculoplastic specialist is also required.

For patients who cannot be on systemic immunosuppression for other health reasons such as diabetes or cancer, they may require an artificial corneal transplantation. The artificial corneal transplantation is reserved as a last step for visual rehabilitation in these eyes. The only artificial cornea that has shown potential, is the Boston keratoprosthesis. Even this artificial cornea carries a high risk for infection and glaucoma. Very close monitoring of eyes that have an artificial cornea is required to monitor for infection and glaucoma progression. However these eyes do not require systemic immunosuppression.

Eye with Boston keratoprosthesis
Eye with Boston keratoprosthesis


The management of eyes with severe ocular surface disease is a difficult one for the cornea specialist. A subspecialist in severe ocular surface disease and limbal stem cell transplantation is required to manage these very sick eyes. At the Gavin Herbert Eye Institute, we have developed a team approach for the management of severe ocular surface disease patients and have successfully treated and are managing many patients who have otherwise no place to go.

Farid 3.6.14Marjan Farid, MD
Director of Cornea, Cataract, and Refractive Surgery
Vice-Chair of Ophthalmic Faculty
Director of the Cornea Fellowship Program
Associate Professor of Ophthalmology
Gavin Herbert Eye Institute, University of California, Irvine

What Are The Differences In The Immune System of An Age-related Macular Degeneration Patient?

A symposium was held in Bethesda, Maryland at the National Institutes of Health on March 6, 2014.  The purpose was to bring together clinicians and researchers from a wide variety of background to discuss the recently discovered differences in the function of the immune system in patients with age-related macular degeneration (AMD) and how it relates to aging.  These differences are important to understand because they may lead to new therapeutic approaches to treat people which are high risk for AMD.

Courtesy of National Eye Institute, National Institutes of Health - immune system
Courtesy of National Eye Institute, National Institutes of Health

  • Three researchers associated with the Discovery Eye Foundation attended the one-day conference.  Cristina Kenney, MD, PhD, has worked in the field of AMD for over twelve years and is a leading expert on the genetics and molecular changes in the mitochondria as it related to the retinal cell death associated with AMD.
  • Lbachir BenMohamed, PhD, is an expert immunologist with a tremendous understanding of how the immune system responds to infections and stress.
  • Anthony Nesburn, MD, has been involved in AMD research at both the clinical and research levels.

By attending this meeting, all three researchers gained insight into the importance of the immune system with respect to maintaining a healthy retina and slowing the progression of AMD.

The highlights of the meeting were the following:

1.  Emily Chew, MD (National Eye Institute) reviewed the clinical aspects of the disease stressing that there are many stages of AMD.

The early stage of AMD is diagnosed based upon the medium-size drusen (about the width of an average human hair) that can be seen underneath the retina.  There may not be any visual changes in these patients.

The intermediate stage of AMD is when subjects have larger drusen and some degree of retinal pigment epithelial cell drop out.  These patients may not have vision loss or other symptoms.

The late stages of AMD which can be categorized into the dry form (geographic atrophy) which has significant loss of the retinal pigment epithelial cells and overlying photoreceptor cells.  Presently there in no treatment for this type of AMD.

These individuals can have changes that cause decreased vision.  The second form of late AMD is the wet form (neovascular), which has growth of abnormal blood vessels beneath the retina that can cause significant loss of vision.  The treatments for this type of AMD are anti-VEGF medications that block the growth of these vessels and help maintain good visual acuity.

2.  Anand Swaroop, PhD (National Eye Institute) reviewed the genetics of AMD and summarized the work of numerous laboratories.  It is now recognized that there are over 20 different genes associated with AMD.  These genes fall into the categories of those involved with Complement Activation, Cholesterol Pathway, Angiogenesis, Extracellular Matrix and Signaling Pathways.  Many of these genes have additive effects, meaning that if a patient has more than one high risk gene, then the likelihood of developing AMD increases.  While we have learned a lot about the genes that are important, we still do not have any gene therapies that can be used to treat AMD.

3.  Six different speakers presented their data related to animal models of AMD and it was agreed that there is not a “perfect” model because most of the animals do not have a macula, the region of the retina that is affected the most by AMD.  However, there is still a lot to be learned by using the models that we do have because if we can better understand the basic pathways involved, then we can block or modify the pathways to prevent the damage.

4.  Jayakrishna Ambati, PhD (University of Kentucky) presented data showing that there is a deficiency of an enzyme called DICER1 in the retinal pigment epithelial cells which leads to increased activation of inflammation via a protein complex called the inflammasome.  He described some of the signaling pathways which are involved in the inflammasome activation.  This is important because these pathways can become targets for treatment of the dry form of AMD.

5.  Jae Jin Chae, PhD (National Human Genome Research Institute) also talked about the role that inflammation plays in the development of AMD.  The data presented reviewed the pathways involved with activation of the inflammasomes which is the first step in a cascade of events that result in inflammatory diseases.  They have identified a calcium-sensing receptor (CASR) which triggers the activation of the NLRP3, a key component of the inflammasome.  Understanding how this series of events works allows researchers to develop medications to block or interfere with the pathway and therefore decrease the levels of inflammation.  

Dr. M. Cristina KenneyM. Cristina Kenney, MD, PhD
Professor and Director of Ophthalmology Research
School of Medicine, Dept. of Ophthalmology
University of California, Irvine