Joseph C. Giacalone

Concise Review: Patient-Specific Stem Cells to Interrogate Inherited Eye Disease

Whether we are driving to work or spending time with loved ones, we depend on our sense of vision to interact with the world around us. Therefore, it is understandable why blindness for many is feared above death itself. Heritable diseases of the retina, such as glaucoma, age‐related macular degeneration, and retinitis pigmentosa, are major causes of blindness worldwide. The recent success of gene augmentation trials for the treatment of RPE65‐associated Leber congenital amaurosis has underscored the need for model systems that accurately recapitulate disease. With the advent of patient‐specific induced pluripotent stem cells (iPSCs), researchers are now able to obtain disease‐specific cell types that would otherwise be unavailable for molecular analysis. In the present review, we discuss how the iPSC technology is being used to confirm the pathogenesis of novel genetic variants, interrogate the pathophysiology of disease, and accelerate the development of patient‐centered treatments.

Connective Tissue Growth Factor Promotes Efficient Generation of Human induced pluripotent stem cell-Derived Choroidal Endothelium.

Age‐related macular degeneration (AMD) is a leading cause of irreversible blindness in the Western world. Although, the majority of stem cell research to date has focused on production of retinal pigment epithelial (RPE) and photoreceptor cells for the purpose of evaluating disease pathophysiology and cell replacement, there is strong evidence that the choroidal endothelial cells (CECs) that form the choriocapillaris vessels are the first to be lost in this disease. As such, to accurately evaluate disease pathophysiology and develop an effective treatment, production of patient‐specific, stem cell‐derived CECs will be required. In this study, we report for the first time a stepwise differentiation protocol suitable for generating human iPSC‐derived CEC‐like cells. RNA‐seq analysis of the monkey CEC line, RF/6A, combined with two statistical screens allowed us to develop media comprised of various protein combinations. In both screens, connective tissue growth factor (CTGF) was identified as the key component required for driving CEC development. A second factor tumor necrosis factor (TNF)‐related weak inducer of apoptosis receptor was also found to promote iPSC to CEC differentiation by inducing endogenous CTGF secretion. CTGF‐driven iPSC‐derived CEC‐like cells formed capillary tube‐like vascular networks, and expressed the EC‐specific markers CD31, ICAM1, PLVAP, vWF, and the CEC‐restricted marker CA4. In combination with RPE and photoreceptor cells, patient‐specific iPSC derived CEC‐like cells will enable scientists to accurately evaluate AMD pathophysiology and develop effective cell replacement therapies. Stem Cells Translational Medicine 2017;6:1533–1546

CRISPR-Cas9 genome engineering: Treating inherited retinal degeneration.

&NA; Gene correction is a valuable strategy for treating inherited retinal degenerative diseases, a major cause of irreversible blindness worldwide. Single gene defects cause the majority of these retinal dystrophies. Gene augmentation holds great promise if delivered early in the course of the disease, however, many patients carry mutations in genes too large to be packaged into adeno‐associated viral vectors and some, when overexpressed via heterologous promoters, induce retinal toxicity. In addition to the aforementioned challenges, some patients have sustained significant photoreceptor cell loss at the time of diagnosis, rendering gene replacement therapy insufficient to treat the disease. These patients will require cell replacement to restore useful vision. Fortunately, the advent of induced pluripotent stem cell and CRISPR‐Cas9 gene editing technologies affords researchers and clinicians a powerful means by which to develop strategies to treat patients with inherited retinal dystrophies. In this review we will discuss the current developments in CRISPR‐Cas9 gene editing in vivo in animal models and in vitro in patient‐derived cells to study and treat inherited retinal degenerative diseases.

Choosing surgery as a career: Early results of a longitudinal study of medical students

Background: Few studies have explored the factors associated with the preference of medical students to pursue a specific specialty, and even fewer have observed how these preferences and factors change over time. Methods: A longitudinal survey of medical students was administered at the beginning of first year, second year, and clerkships from 2013–2016. Surveys included demographics and factors associated with their choice of specialty. Results: Response rates were 78–94%. Students with mentors and research experience in any specialty were 3.4 times (P < .001) more likely to choose surgery by their third year of medical school. Surgical research experience on the first‐ and second‐year surveys was associated with 39 (P < .001) and 10 times (P < .001) greater odds of preferring surgical specialties on their third‐year survey. Medical students who had a surgery mentor during the first and second years were associated with 4 (P = .024) and 13 times (P < .001) greater odds of preferring surgical specialties on their third‐year survey. Conclusion: Students who begin surgical research during their first year and develop relationships with surgeon mentors during their second year are significantly more likely to maintain an interest in surgical specialties.