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Imidazole Compounds for Protecting Choroidal Endothelial Cells from Complement Injury.

Wed, 2018-09-12 22:21
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Imidazole Compounds for Protecting Choroidal Endothelial Cells from Complement Injury.

Sci Rep. 2018 Sep 06;8(1):13387

Authors: Zeng S, Wen KK, Workalemahu G, Sohn EH, Wu M, Chirco KR, Flamme-Wiese MJ, Liu X, Stone EM, Tucker BA, Mullins RF

Abstract
Age-related macular degeneration (AMD) is a common, blinding disease associated with increased complement system activity. Eyes with AMD show elevated accumulation of the membrane attack complex (MAC) in the choriocapillaris and degeneration of macular choriocapillaris endothelial cells (ECs). Thus, one could reasonably conclude that the endothelial cell death that occurs in AMD is due to injury by the MAC. We therefore sought to identify strategies for protecting ECs against MAC lysis. RF/6A endothelial cells were pre-incubated with a library of FDA-approved small molecules, followed by incubation with complement intact human serum quantification of cell death. Two closely related molecules identified in the screen, econazole nitrate and miconazole nitrate, were followed in validation and mechanistic studies. Both compounds reduced lysis of choroidal ECs treated with complement-intact serum, across a range of doses from 1 to 100 µM. Cell rescue was confirmed in mouse primary choroidal ECs. Both exosome release and cell surface roughness (assessed using a Holomonitor system) were reduced by drug pretreatment in RF/6A cells, whereas endosome formation increased with both drugs, consistent with imidazole-mediated alterations of cell surface dynamics. The results in the current study provide further proof of principle that small molecules can protect choroidal ECs from MAC-induced cell death and suggest that FDA approved compounds may be beneficial in reducing vascular loss and progression of AMD.

PMID: 30190604 [PubMed - in process]

Effect of Molecular Weight and Functionality on Acrylated Poly(caprolactone) for Stereolithography and Biomedical Applications.

Wed, 2018-08-01 11:24
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Effect of Molecular Weight and Functionality on Acrylated Poly(caprolactone) for Stereolithography and Biomedical Applications.

Biomacromolecules. 2018 Jul 25;:

Authors: Green BJ, Worthington KS, Thompson JR, Bunn SJ, Rethwisch M, Kaalberg EE, Jiao C, Wiley LA, Mullins RF, Stone EM, Sohn EH, Tucker BA, Guymon CA

Abstract
Degradable polymers are integral components in many biomedical polymer applications. The ability of these materials to decompose in situ has become a critical component for tissue engineering, allowing scaffolds to guide cell and tissue growth while facilitating gradual regeneration of native tissue. The objective of this work is to understand the role of prepolymer molecular weight and functionality of photocurable poly(caprolactone) (PCL) in determining reaction kinetics, mechanical properties, polymer degradation, biocompatibility, and suitability for stereolithography. PCL, a degradable polymer used in a number of biomedical applications, was functionalized with acrylate groups to enable photopolymerization and 3D printing via stereolithography. PCL prepolymers with different molecular weight and functionality were studied to understand the role of molecular structure on reaction kinetics, mechanical properties and degradation rates. The mechanical properties of photocured PCL were dependent on cross-link density and directly related to the molecular weight and functionality of the prepolymers. High molecular weight, low functionality PCLDA prepolymers exhibited lower modulus and higher strain at break while low molecular weight, high functionality PCLTA prepolymers exhibited lower strain at break and higher modulus. Additionally, degradation profiles of cross-linked PCL followed a similar trend, with low cross-link density leading to degradation times up to 2.5 times shorter than more highly cross-linked polymers. Furthermore, photopolymerized PCL showed biocompatibility both in vitro and in vivo, causing no observed detrimental effects on seeded murine induced pluripotent stem cells or when implanted into pig retinas. Finally, the ability to create 3-dimensional PCL structures is shown by fabrication of simple structures using digital light projection stereolithography. Low molecular weight, high functionality PCLTA prepolymers printed objects with feature sizes near the hardware resolution limit of 50 μm. This work lays the foundation for future work in fabricating micro-scale PCL structures for a wide range of tissue regeneration applications.

PMID: 30044915 [PubMed - as supplied by publisher]

Evaluation of serum and ocular levels of membrane attack complex and C-reactive protein in CFH-genotyped human donors.

Wed, 2018-07-18 06:45
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Evaluation of serum and ocular levels of membrane attack complex and C-reactive protein in CFH-genotyped human donors.

Eye (Lond). 2018 Jul 16;:

Authors: Chirco KR, Flamme-Wiese MJ, Wiley JS, Potempa LA, Stone EM, Tucker BA, Mullins RF

Abstract
BACKGROUND: There is a considerable body of evidence demonstrating a link between the membrane attack complex (MAC) and age-related macular degeneration (AMD), and between C-reactive protein (CRP) and AMD. Both the MAC and the monomeric form of CRP (mCRP) accumulate within the choriocapillaris in AMD. However, the precise contribution of these species to AMD pathophysiology has not been fully elucidated.
METHODS: We sought to directly assess CRP and MAC levels between human serum and ocular tissues from the same CFH Y402H genotyped donors using ELISA of serum and RPE/choroid proteins.
RESULTS: The Y402H polymorphism was associated with significantly increased MAC in RPE/choroid samples, but not in the serum, in a previously unstudied cohort. While MAC levels in the choroid were independent of circulating levels, choroidal CRP was correlated to serum levels.
CONCLUSIONS: These data provide further evidence for local activation of complement within the choriocapillaris in AMD.

PMID: 30013157 [PubMed - as supplied by publisher]