(810.1) Normalization of Oxygen-Induced Retinopathy in the Mouse Supplementation with Myo/Nog Cells

Poster Board Number: A326

Christopher Sutera (Philadelphia College of Osteopathic Medicine), Grace Wilgucki (Philadelphia College of Osteopathic Medicine), Edgar Weyback (Philadelphia College of Osteopathic Medicine), E-Jine Tsai (Philadelphia College of Osteopathic Medicine), Rushil Brahmbhatt (Philadelphia College of Osteopathic Medicine), Mark Martin (Philadelphia College of Osteopathic Medicine), Sarah Adams (Philadelphia College of Osteopathic Medicine), Paul Lecker (Philadelphia College of Osteopathic Medicine), Karanveer Johal (Philadelphia College of Osteopathic Medicine), John Spikes (Philadelphia College of Osteopathic Medicine), Grzegorz Gorski (Philadelphia College of Osteopathic Medicine), Jacquelyn Gerhart (Philadelphia College of Osteopathic Medicine), Nancy Philp (Thomas Jefferson University), Mindy George-Weinstein (Philadelphia College of Osteopathic Medicine), Arturo Bravo-Nuevo (Philadelphia College of Osteopathic Medicine)

Introduction: Retinopathy of Prematurity (ROP) is the leading cause of blindness in children, affecting 50% of infants born prior to gestational week 32. ROP is the result of postpartum supplemental oxygen administered to compensate for underdeveloped lungs. However, hyperoxia inhibits proper development supplying the retina. When the infants are returned to ambient air, an imbalance is present between the oxygen concentration and metabolic demands of retinal neurons. This leads to a rapid induction of angiogenesis, leaky blood vessels, neovascular tuft formation, and cell death. Myo/Nog cells that express MyoD, Noggin, and brain-specific angiogenesis inhibitor 1 (BAI1) exhibit neuroprotective properties in the eye and brain and are proposed to play a role in regulating angiogenesis in ROP.

Methods: An Oxygen-induced retinopathy (OIR) protocol was implemented in neonatal C57BL/6J mice by exposing them on postnatal days 7-12 (P7-P12) to hyperoxia (75% oxygen) and then returning them to normal air (21% oxygen) from P12 until P21. On P15, groups receiving treatments were intravitreally injected with 1 µL of phosphate-buffered saline (PBS) containing 2000 Myo/Nog cells isolated from the brain with the BAI1 antibody (BAI1+ group), 2000 unsorted brain cells (BAI1- group), or PBS alone (PBS group). Electroretinography (ERG) was conducted on P21 to assess retinal function.  Eyes were extracted and either dissected for flat-mount observation of vasculature and tufts, or processed for histology. The thickness of the retina and number of TUNEL+ apoptotic cells were quantified in tissue sections of eyes processed for histology. Adobe Photoshop (Adobe, San Jose, CA) was used to splice together 9 images that made up each whole retina from flat-mounted eyes. The blood vessels were selected using the “Lasso tool” on photoshop, quantified by number of pixels, and then compared to the total number of pixels in the whole retina.

Results: OIR induced neovascular tuft formation. Exogenously added Myo/Nog cells normalized the retinopathy induced by the OIR model, reducing the number of tufts and improving the quality of the vasculature. The vasculature was most developed in retinas injected with brain derived Myo/Nog cells. ERG data shows a trend towards improvement of visual function with Myo/Nog cell injection.

Conclusion: Myo/Nog cell regulation of retinal vascularization may be related to the production of BAI1. Improved visual function seen with injection of Myo/Nog cells may be related to both a reduction of neovascular tufts and direct effects on retinal neurons. Therefore Myo/Nog cells have therapeutic potential in the prevention of ROP by normalizing the vasculature and preventing neuronal cell death.