Intracerebral Hemorrhage Models in Rat: Comparing Collagenase to Blood Infusion

Abstract

Many therapies have shown promise in preclinical stroke studies, but few benefit patients. A greater understanding of stroke pathophysiology is needed to successfully develop therapies, and this depends on appropriate animal models. The collagenase and blood infusion models of intracerebral hemorrhage (ICH) are widely used; yet, investigators often prefer using one model for a variety of reasons. Thus, we directly compared these to highlight advantages and limitations of each as well as the assessment approach. An ICH was created by infusing blood or bacterial collagenase into the rats' striatum. We matched initial hematoma volume in each model (Experiment 1) and assessed the time course of bleeding (Experiment 2). Functional deficits and the progression of injury were tracked over 6 weeks using behavior, magnetic resonance imaging, and histology (Experiment 3). Despite similar initial hematoma volumes, collagenase-induced ICH resulted in a greater bloodbrain barrier breakdown and more damage to the striatum, substantia nigra, white matter, and cortex. Magnetic resonance imaging revealed faster hematoma resolution in the blood model, and little increase in the volume of tissue lost from 1 to 6 weeks. In contrast, tissue loss continued over 4 weeks in the collagenase model. Finally, functional deficits recovered more quickly and completely in the blood model. This study highlights key differences between these models and that neither closely replicates the human condition. Thus, both should be used whenever possible taking into account the significant differences between these models and their limitations. Furthermore, this work illustrates significant weaknesses with several outcome measures.

Mouse Intracerebral Hemorrhage Models Produce Different Degrees of Initial and Delayed Damage, Axonal Sprouting, and Recovery

“…29 Some of the effects of bICH and cICH in the mouse are distinct to that seen in the rat. Behavioral deficits persist for a greater period in rat cICH 26,30 than in the mouse. Unlike in rat, sensorimotor deficits as measured by gait in the mouse resolve sooner in cICH than bICH.…”

“…In rat cICH, there is loss of connections to the striatum with a modest reduction in neurons that project from the substantia nigra to the striatum, 31 a decrease in cortical projections from the ipsilateral motor cortex 32 and thinning of ipsilateral cortex. 26 There are no reports of axonal loss in the rat in bICH. This greater loss of axonal projections to the striatum in cICH in the mouse could be due to greater local tissue damage after the hemorrhage.…”

Experimental Intracerebral Hemorrhage: Avoiding Pitfalls in Translational Research

“…The development of cerebral edema has a stronger temporal association with neurologic deterioration in the autologous blood injection model compared with the collagenase model, and is slower and more protracted in human compared with experimental ICH (Butcher et al, 2004;Gebel et al, 2002a;Hua et al, 2003;Qureshi et al, 2009;Rosenberg et al, 1990;Yang et al, 1994)-as is red cell resorption (Butcher et al, 2004;MacLellan et al, 2008;Xi et al, 2006). Further, when matched for hematoma size, the total loss of brain tissue can be twice as much in the collagenase model compared with the blood injection model (MacLellan et al, 2008). All of these differences suggest the need for the trialing of putative neuroprotectants with multiple models and outcome measures.…”

In vivo iron quantification in collagenase‐induced microbleeds in rat brain

“…1 and 3f-i). Although an established intracerebral hemorrhage rat model typically delivers 0.2 U of collagenase in 1 mL of saline (46,47), the smaller doses and volumes used in this study reflect an attempt to induce smaller and more focal hemorrhagic legions to better model BMB. However, it appears the collagenase injections caused bleeding that is more spatially diffuse than is characteristic of real BMB which generally originate from a single ruptured vessel (25).…”