br Conclusions The following are the supplementary data
Conclusions The following are the supplementary data related to this article.
Conflict of interest
Acknowledgements This work was supported by The Danish Cancer Society (R.C. Grant number DP07024); Kgl. Hofbundtmester Aage Bang Fund (Grant number 55-07/08); Karen Elise Jensen Fund; Karen Kriegers Fund (Grant number 06203050); Lundbech Foundation (Grant number R19-A2286) and Danish Ministry of Higher Education and Science through Danish Center for Transgenic Mice. We are grateful to Anette Thomsen and Christian Knudsen for excellent technical assistance and Lisbeth Ahm Hansen for purchase mg115 injection.
Introduction Closed head injury (CHI) is the result of an immediate mechanical insult to the central nervous system (CNS). Patients with CHI suffer from neurological impairments and require long-term care (Bramlett and Dietrich, 2015). CHI-induced neurological deficits are caused by several intertwined phenomena, such as cerebral edema, blood-brain barrier (BBB) disruption, neuronal loss, astroglial scarring and inflammation (Abdul-Muneer et al., 2015; Sofroniew, 2015; Das et al., 2012). Accumulating evidence indicates that inflammation following trauma, including immune cell recruitment and cytokine production, plays a crucial role in neural injury and functional reconstruction (Das et al., 2012; Corps et al., 2015; Gage and Temple, 2013). Therefore, inflammation modulation, which may promote recovery of damaged brain tissue, may represent a promising therapeutic intervention for CHI patients. In recent decades, scholars have noted that in addition to facilitating cell replacement, transplanted neural stem cells (NSCs) can support resident CNS cells by secreting neurotrophic factors and can improve neurological outcomes by immunoregulating various disorders (Ager, 2015; Lemmens and Steinberg, 2013; Dooley et al., 2014). Currently, with advances in reprogramming technology, induced neural stem cells (iNSCs) generated directly from autologous somatic cells are more suitable for clinical use than NSCs because their capacities for self-renewal and multi-lineage differentiation are similar to those of NSCs, and their use is not fraught with the ethical concerns or resource limitations associated with NSC use (Yao et al., 2015; Gao et al., 2016). We previously reported that iNSCs directly reprogrammed from mouse embryonic fibroblasts can expand and give rise to neurons, astrocytes and oligodendrocytes (Yao et al., 2015). Moreover, we noted that there were no significant differences in the levels of several neurotrophic factors between iNSC and NSC culture supernatants. In particular, we found that iNSC grafts accelerated neurological recovery in middle cerebral artery occlusion (MCAO) animals and a portion of iNSCs differentiated into glial fibrillary acidic protein (GFAP)-positive astrocytes and beta III tubulin (Tuj1)-positive neural cells in MCAO-damaged brains. These findings suggested that iNSCs, similar to NSCs, can play roles in cell replacement and neurotrophy in CNS regeneration. INSCs have many NSC-like characteristics, but they are not identical to NSCs because transdifferentiation technology may cause genetic or epigenetic variations (Zhao et al., 2011). For instance, induced pluripotent stem cells (iPSCs), which had previously been considered identical to embryonic stem cells (ESCs), can express different sets of genes and proteins that may evoke unwanted immune rejection after grafting (Zhao et al., 2011). Hence, it is essential to carefully determine iNSC potential in pre-clinical research. Moreover, whether iNSCs have immunomodulatory properties remains uncertain, and few studies have evaluated the effects of iNSC grafts in syngeneic mouse models of CHI. In this study, we aimed to determine the role of engrafted iNSCs in CNS recovery following CHI-induced neurological impairment, as well as the mechanisms underlying this role. Mouse models of CHI were established using a standardized weight-drop device and assessed by neurological severity score (NSS) (Flierl et al., 2009; Xiong et al., 2013). Although these models fail to mimic the complete spectrum of human CHI, they represent a clinically encountered injury mechanism and reproduce impairment in neurological function observed in CHI patients (Flierl et al., 2009). Syngeneic iNSCs or NSCs were separately transplanted into the brains of CHI mice at 12h after CHI. Neurological impairment post-CHI was evaluated by several tests. Animals were sacrificed for morphological and molecular biological analyses.