Direct Differentiation of Adult Ocular Progenitors into Striatal Dopaminergic Neurons

Parkinson's disease, characterized by motor dysfunction due to the loss of nigrostriatal dopaminergic neurons, is one of the most prevalent age-related neurodegenerative disorders. Given there is no current cure, the stem cell approach has emerged as a viable therapeutic option to replace the dopaminergic neurons that are progressively lost to the disease. The success of the approach is likely to depend upon accessible, renewable, immune compatible, and non-tumorigenic sources of neural progenitors from which stable dopaminergic neurons can be generated efficaciously. Here, we demonstrate that neural progenitors derived from limbus, a regenerative and accessible ocular tissue, represent a safe source of dopaminergic neurons. When the limbus-derived neural progenitors were subjected to a well-established protocol of directed differentiation under the influence of Shh and FGF8, they acquired the biochemical and functional phenotype of dopaminergic neurons that included the ability to synthesize dopamine. Their intrastriatal transplantation in the rat model of hemi-Parkinsonism was associated with a reduction in the amphetamine-induced rotation. No tumor formation was observed 6 weeks post-transplantation. Together, these observations posit limbus-derived neural progenitors as an accessible and safe source of dopaminergic neurons for a potential autologous ex-vivo stem cell approach to Parkinson's disease.

Diagnostic utility of polymerase chain reaction on intraocular specimens to establish the etiology of infectious endophthalmitis.

PURPOSE: To evaluate the utility of polymerase chain reaction (PCR) on intraocular clinical specimens (aqueous humor [AH] and vitreous fluid [VF]) as an etiologic diagnostic tool relative to microbiological culture methods in infectious endophthalmitis. METHODS: Conventional bacterial and mycologic cultures and PCR for eubacterial and panfungal genomes were applied for etiologic diagnosis on pairs of AH and VF obtained from 72 patients with clinically established infectious endophthalmitis. RESULTS: Based on cultures, an infectious etiology was established in 27 (37.5%) of 72 patients. PCR detected infectious etiology in all 72 patients. PCR increased the clinical sensitivity over culture by 62.5% (p<0.0001, McNemar test). The frequency of culture positivity, single infections, and polymicrobial infection varied significantly among the types of endophthalmitis (p<0.0001, chi-square test). PCR detected an infectious etiology in 48 patients and polymicrobial infection in 24 patients. An etiology was established by PCR on 56 (77.8%) AH and 65 (90.3%) VF of the 72 patients and this difference had no statistical significance. CONCLUSIONS: PCR on intraocular specimens as an etiologic diagnostic tool has been shown to be specific and severalfold more sensitive than cultures and clinically useful. Therefore, PCR may be considered the gold standard to establish the etiology of infectious endophthalmitis. As there is no statistically significant difference in the results of PCR on AH and VF, PCR on AH could be the method of choice considering safety and simplicity of the procedure of its collection.