Time-dependent Microglia and Macrophages Response after Traumatic Spinal Cord Injury in Rat: A Systematic Review

Abstract Objective : To acquire evidence-based knowledge in temporal and spatial patterns of microglia/macrophages changes to facilitate finding proper intervention time for functional restoration after traumatic spinal cord injury (TSCI). Setting : Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran, Iran. Methods : We searched PubMed and EMBASE via Ovid SP with no temporal and linguistic restrictions. Besides, hand-search was performed in the bibliographies of relevant studies. The experimental non-interventional and non-transgenic animal studies confined to the rat species which assess the pathological change of microglia /macrophages at the specified time were included. Results : We found 15,315 non-duplicate studies. Screening through title and abstract narrowed down to 607 relevant articles, 31 of them were selected based on the inclusion criteria. The reactivity of the microglia/macrophages initiates in early hours PI in contusion, compression and transection models. Cells activity reached a maximum within 48 hours to 28 days in compression, 7 days in contusion and between 4 to 60 days in transection models. Inflammatory response occurred at the epicenter, in or near the lesion site in both gray and white matter in all three injury models with a maximum extension of one centimeter caudal and rostral to the epicenter in the gray matter in contusion and transection models. Conclusion : This study was designed to study spatial-temporal changes in the activation of microglia/macrophages overtime after TSCI. We were able to demonstrate time-dependent cell morphological changes after TSCI. The peak times of cell reactivity and the areas where the cells responded to the injury were determined.