Biocompatibility of a Novel Microfistula Implant in Nonprimate Mammals for the Surgical Treatment of Glaucoma.

PURPOSE: The purpose of this study was to evaluate the ocular safety of a novel microfistula implant and its composite materials in an animal model. METHODS: The anterior chambers of 12 rabbit eyes were injected with either glutaraldehyde cross-linked porcine gelatin extract or balanced salt solution and were followed by serial slit lamp examinations over 3 days. The eyes of 18 canines underwent microfistula implantation or a sham procedure. The animals were monitored over the subsequent 12 months, using serial slit lamp examinations, indirect ophthalmoscopy, tonometry, specular microscopy, and high-resolution ultrasonography. Ocular tissues were examined histopathologically on postoperative days 7, 30, 90, 180, and 365. RESULTS: Glutaraldehyde cross-linked porcine gelatin did not induce significant intraocular inflammation in the rabbit model. The microfistula implant was well tolerated and did not stimulate significant tissue response in the canine eye. The microfistula tube did not undergo structural change or degradation over the course of the study. CONCLUSIONS: In nonprimate mammals, the material composing the microfistula implant and the implant itself do not induce significant inflammation or tissue reaction.

Preclinical study design for evaluation of stem cell-derived cellular therapy products: a pathologist's perspective.

Despite-or perhaps because of-the rapid expansion of interest in stem cell-derived cellular therapy products, relatively few guidelines have been published to assist in the design of scientifically sound preclinical studies. The field is complex and wide ranging, and of necessity regulators tend to treat each project on a case by case basis. One of the core tenets remains the need to retain all tissues from the study, thereby allowing for further analysis of tissues should unexpected effects be seen in clinical studies; attempts to comply with this may result in an unmanageable financial burden. Judicious input from the pathologist at the earliest stages of study design may not only improve the scientific integrity of the study but also help to mitigate some of the cost. Careful animal selection, the development of robust cell markers, and justifiable triage of tissues based on phased tissue examination can all be discussed with the regulatory authorities at pre-pre-investigational new drug (IND) and pre-IND meetings to achieve optimal study design.