Abstract
Purpose :
The purpose of this study was to produce and characterize a tissue engineered (TE) choroidal stroma that could serve as a carrier for retinal pigment epithelium transplantation.
Methods :
Human choroidal fibroblasts (n=8) were cultured during 6 weeks in the presence of ascorbic acid to promote extracellular matrix (ECM) assembly. Two sheets were stacked, then cultured for another week. To measure the contractility (n=4), images were taken with a stereo microscope at 1, 10, 30, 60 and 120 min after a circular cut (diameter = 10 mm). The percentage of contractility was determined by using the formula (1 – final area/initial area) *100. ECM composition (n=4) was analyzed by immunostainings (collagens and glycoproteins) with native choroids as controls. Thickness of contracted TE-stromas was assessed on histology cross-sections and calculated using Image J analysis software (25 measurements per section, 3 sections per population). Finally, the mechanical properties of the TE-stromas were evaluated (n=3) using a uniaxial tension test. The ultimate tensile strength (UTS) was the maximum stress that the TE-stromas can withstand while being stretched before tearing up, and the elasticity modulus (E) was the ration of strain to stress.
Results :
The contractility assays showed that the TE-stromas contracted by themselves for 10 min (79.35 ± 7.95%) before stabilizing. Type I, IV, V, VI collagens, as well as decorin and tenascin C were found in both TE-stromas and native choroids. Contracted TE-stromas were 133.44 ± 39.44 μm thick. UTS TE-stromas was three times as high as the control whereas ETE-stromas was 12 times as low.
Conclusions :
At least a 10 minute-wait should be allowed after cutting the TE-stroma before grafting, in order to avoid generating retinal detachment. The composition of ECM proteins of the TE-stromas was similar to the native tissue. The two-sheet stromas were 3 times as thin as the native choroid, which could facilitate the reestablishment of blood circulation and diffusion of nutrients from the choroid to the RPE and photoreceptors. Our TE-stromas were stiffer than native choroid, but they resisted more tension. These tissue-engineered (TE) stromal substitutes could serve as carriers for RPE transplantation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.