Steven D. Garner First
Published: 17 January 2018
Key Clinical Message
Clinical management of keratoconjunctivitis sicca with a single injection of stem cells into the lacrimal glands. Safe, effective, natural therapy saves chronic daily ophthalmic drug administration.
Keratoconjunctivitis sicca (KCS), also known as “dry eye syndrome,” is a common ocular disease in dogs resulting from lacrimal gland (LG) inflammation and decreased tear production. Tears are the primary source of nutrition for the cornea. The lack of tears from KCS results in inflammation of the cornea and the surrounding tissues causing potential damage to the ocular surface (1), (2). This damage is characterized by the presence of mucoid ocular discharge, conjunctival hyperemia, blepharospasm, recurrent corneal ulceration, corneal ascularization, fibrosis, and, eventually, corneal pigmentation. In severe cases, dense corneal hyperpigmentation and opacification or corneal ulceration can lead to blindness or even loss of the eye (3) (4) (5). The diagnosis of KCS is based on the clinical signs and by the Schirmer tear test (STT). The STT determines whether the eye produces enough tears to keep it moist and ranges from normal (15–25 mm/min), mild (9–14 mm/min), moderate (>4 to 8 mm/min), to severe (>4 mm/min) (4). Any condition that impairs the ability to produce adequate amounts of tear film can result in KCS (1) . Local immune-mediated disease is the most widely accepted cause of KCS based on histopathology of tear-producing glands and on the clinical response to immunomodulators (1) (6) (7). However, other systemic diseases may also be associated with KCS, such as infection with canine distemper virus, ypothyroidism, diabetes mellitus, Cushing’s disease, and certain systemic medications (8), (9).
The most common treatment for KCS is the prescription of artificial tears solutions with or without the addition of immunosuppressive drugs, such as cyclosporine or tacrolimus (10). This case report demonstrates the technique, efficacy and safety of using a single injection of fresh allogenic mesenchymal stem cells (MSCs) into the lacrimal glands to reestablish normal tear production, reduce inflammatory response and return the cornea and surrounding tissues to a more normal state (11). A single transplantation of MSCs (1 × 10 6 ) directly into lacrimal glands (dorsal and accessory gland of the third eyelid) was performed Figure 1. The (STTs) and visible ocular surface improvements were used to assess the effects of these cells. The STTs were carried out on day 0 (before MSCs transplantation) and on days 7, 14 and 21. This case demonstrates allogeneic MSC transplantation in KCS dogs is safe and effective for KCS. In contrast to immunosuppressive drug use, MSC transplantation has an effect over an extended period (up to 12 months), even after a single administration, and does not require daily drug administration.
An 11-year-old spayed female Shi Tzu cross presented with a chronic history of ocular inflammation, matting of the eyes and rubbing of the face with the paws. The client complained that the pet would wake up with the eyes matted shut. Examination revealed mucopurulent crusts on the eyelids and periocular hair.
The corneas of each eye were partially opaque and there was a marked episcleritis. The intra ocular pressures in both eyes were normal at 20 mm Hg. Both eyes were affected equally but the right eye has a small tumor in the margin of the upper eyelid that is causing some irritation. Pigmentation of the corneas was present upon close examination indicating a more chronic nature to the problem. At presentation the STT in the left eye was 13mm and 9mm in the right eye indicating this to be a mild case of KCS base on STT tests. The inflammatory component was however judged to be severe.
Stem Cells were prepared from fresh, third passage (P3) cultures of adipose derived mesenchymal cells from donor animals. One million live cells were prepared into a total solution of 0.5ml for each eye. The pet was anesthetized and maintained with sevoflurane gas anesthesia. Each eye received injections into the lacrimal glands (LG). The dorsal LG received 0.3ml of the solution and the lacrimal gland of the third eyelid received 0.2ml of cell suspension. To access the dorsal LGs, the needle was inserted through the conjunctival fornix of the upper eyelid in a dorsolateral direction injecting below the orbital ligament, Figure 5 . The remaining 0.2 ml of cell suspension was injected into the accessory gland of the third eyelid, which was accessed by retracting the third eyelid with forceps for access, Figure 4 . The pet was sent home with artificial tears as the only medication.
|Schirmer Tear Test Values|
|Day 0||Day 7||Day 14||Day 21|
|Left Eye||13 mm||18 mm||18 mm||20 mm|
|Right Eye||9 mm||21 mm||20 mm||18 mm|
14 days after the MSC injections the clinical signs had abated and STT values had returned to normal whereas 21 days after therapy the STT values were essentially the same, Table 2 . Corneal pigmentary changes were still present and would likely respond over a longer period or with the addition of corticosteroids. The right eye has more conjunctival redness and mucopurulent discharge that may be related to the irritation of the eyelid tumor, Table 1 . Tumor removal has been performed with laser ablation after the last visit.
KCS is a serious disease of dogs with potential blindness as a result. Once diagnosed, KCS is difficult and
expensive to manage. Clients are reluctant to medicate their pets and compliance is therefore low. Stem cell therapy is today a novel therapy for this illness and appears to be very safe and effective (11). Other studies show that the effects last at least one year with a single injection and possibly for life (2). The procedure is simple and may in the future be done with light sedation and/or local anesthesia,thereby reducing the cost and risk to the pet. Sourcing MSCs for this procedure in the average veterinary hospital is easier and less costly than expected but is beyond the scope of this clinical report.
KCS pathogenesis appears to be an immunologically mediated disease (1), (7). It is well established that
the ability to modulate the immune system plays a fundamental role in almost all the therapeutic effects attributed to MSC cells, rather than their capacity of differentiation into different cell lineage (12), (13),
(14). This property is carried out through the release of a large variety of bioactive substances with autocrine and paracrine effects, called the secretome (14). The secretome includes a huge variety of molecules, including proteins, growth factors, antioxidants, proteasomes, icrovesicles, and exosomes, which target a multitude of biological targets (15), responsible for: production of extracellular matrix as well as anti-apoptotic, anti-fibrotic, chemo-attractive, neuroprotective, morphogenic, angiogenic, antimicrobial, immunomodulatory effects etc. (16) (17) (18). The effects of these factors is to both reduce the inflammation as well as to alter the T cells responsible for the attack on the lacrimal gland.The newly reprogrammed T cells may forever leave the lacrimal gland alone because of the resetting by the stem cell secretome and cell to cell interactions.
Clinical management of Keratoconjunctivitis sicca with a single injection of stem cells into the lacrimal glands is safe effective therapy that could rapidly replace the current artificial tears, cyclosporine and tacrolimus therapy options. This therapy can be performed in the average veterinary hospital for less than a year’s supply of more traditional medications. Veterinary medicine is on the cusp of a new set of treatment options using regenerative strategies.
Dr. Garner is the owner and Chief of Staff at Safari Veterinary Care Centers. Dr. Garner can be reached at the hospital on 281.332.5612 or mobile 281.455.2356, or you can email him at firstname.lastname@example.org .
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