Use of a Juvenile Rabbit Animal Model to Evaluate Therapeutic Interventions for Postoperative Inflammation and Fibrin Formation After Lensectomy

Abstract

PurposeWe used the juvenile rabbit as a model for investigating therapeutic interventions for postoperative inflammation and fibrin formation following intraocular lens (IOL) insertion for management of pediatric cataracts.MethodsTwelve 6- to 7-week-old, 600 to 900 g rabbits underwent bilateral clear-cornea lensectomy via irrigation and aspiration with IOL insertion. Following wound closure, enoxaparin 8 mg (n = 6 eyes), preservative-free triamcinolone 0.5 mg (n = 6), 8 mg enoxaparin plus 0.5 mg triamcinolone (n = 6), or balanced salt solution (n = 6) was injected into the anterior chamber. Slit-lamp examinations and optical coherence tomography (OCT) scans were performed postoperatively on days 3 through 7, and 14 to characterize levels of inflammation and fibrin. Using 17 additional rabbits, enzyme-linked immunosorbent assays (ELISAs) with 100 μL of aqueous humor were performed to quantify the amount of fibrinogen and fibrin preoperatively and on postoperative day 3. Immunohistochemistry was performed to confirm the presence of fibrin.ResultsEnoxaparin alone and combined with triamcinolone reduced the amount of fibrin present in the anterior chamber compared to untreated eyes, which corresponded to an increase in OCT signal strength. Despite the clear visual axis shown in clinical images, the combination treatment group had the highest levels of soluble fibrin when assessed by ELISA. Immunohistochemistry confirmed the presence of insoluble fibrin seen clinically.ConclusionsA combination of enoxaparin and triamcinolone appears to provide the most therapeutic benefit by reducing fibrin formation and postoperative inflammation.Translational RelevanceThe juvenile rabbit is an excellent model to investigate inflammation and fibrin formation following lensectomy with IOL insertion and possibly any intraocular surgery in children.

Tissue Plasminogen Activator Effects on Fibrin Volume and the Ocular Proteome in a Juvenile Rabbit Model of Lensectomy

“…A total of 27 New Zealand White rabbits (Kuiper Rabbit Ranch, Gary, IN), 6 to 7 weeks of age and weighing between 600 and 900 g, were housed in a 14-hour light/10-hour dark cycle and fed a diet of pelleted chow (Laboratory Rabbit Diet High Fiber 5326; LabDiet, St. Louis, MO) daily and a Timothy hay cube twice per week (Bio-Serv, Flemington, NJ). Based on previous studies with preventative pharmacologic therapies where five or six rabbits per group showed significant postoperative differences clinically and in AH proteins, 14 , 15 eyes of either male or female sex per group were chosen to be randomized to the tPA or control balanced salt solution (BSS) group for postoperative treatments (described below). Rabbits were anesthetized with isoflurane (5% induction, 2.5%–4% maintenance) with 2 L/min of oxygen for surgery and postoperative exams.…”

“…POD3 was chosen because (1) we previously classified this day as the peak of the postoperative response, and (2) it allowed us to compare outcomes with our previous clinical and proteomic studies. 14 , 15 The intraocular pressure (IOP) in each eye was measured using a TonoLab tonometer (Icare USA, Raleigh, NC). Slit-lamp biomicroscopy (SL-D8Z Digital-Ready Zoom Slit Lamp; Topcon Medical Systems, Oakland, NJ) was performed with photographs obtained using a Nikon D810 camera (Nikon USA, Melville, NY) to evaluate each eye in the categories of iris synechiae, pupil dilation in millimeters, and presence or absence of hemorrhage in the anterior chamber.…”

“…Our laboratory utilizes a juvenile rabbit animal model to investigate the response following intraocular surgery. 14 , 15 Juvenile rabbits have a robust immune and fibrotic response following lensectomy with IOL insertion, making them an ideal animal for studying treatment outcomes following intraocular surgery. Sampling of the aqueous humor (AH) before and after a surgical intervention can help deduce the mechanisms and proteins responsible for the exaggerated immune response.…”

Quantitative proteomic analysis of aqueous humor after rabbit lensectomy reveals differences in coagulation and immunomodulatory proteins

“…A juvenile rabbit animal model of lensectomy has been shown to have a similar response to surgery and is therefore informative for the study of mechanisms that result in robust inflammation and fibrin formation. 7 In addition, juvenile rabbits exhibit similarities in anterior chamber size and lens diameter, 8 rendering them an ideal animal model for pediatric anterior segment studies utilizing similar techniques and materials to those used in human surgery. Rabbits provide a cost-effective, controlled environment for proteomic and surgical investigations.…”

“…In the current study, MS was used to quantify AH proteome changes in juvenile rabbits subjected to lensectomy with IOL insertion, using a surgical step-wise approach, to identify and quantify proteins responsible for the exaggerated immune response and fibrin formation observed in previous work. 7 This work is the first to combine quantitative proteomics in a juvenile rabbit model following lensectomy with IOL insertion. Combining proteomics with this juvenile animal model provides an opportunity to examine how the ocular immune system responds to a corneal incision versus removal of the lens, thus offering significant insights into which proteins may cause postoperative scarring and inflammation at these specific surgical steps.…”