Spatiotemporal evolution of early innate immune responses triggered by neural stem cell grafting

Abstract

IntroductionTransplantation of neural stem cells (NSCs) is increasingly suggested to become part of future therapeutic approaches to improve functional outcome of various central nervous system disorders. However, recently it has become clear that only a small fraction of grafted NSCs display long-term survival in the (injured) adult mouse brain. Given the clinical invasiveness of NSC grafting into brain tissue, profound characterisation and understanding of early post-transplantation events is imperative to claim safety and efficacy of cell-based interventions.MethodsHere, we applied in vivo bioluminescence imaging (BLI) and post-mortem quantitative histological analysis to determine the localisation and survival of grafted NSCs at early time points post-transplantation.ResultsAn initial dramatic cell loss (up to 80% of grafted cells) due to apoptosis could be observed within the first 24 hours post-implantation, coinciding with a highly hypoxic NSC graft environment. Subsequently, strong spatiotemporal microglial and astroglial cell responses were initiated, which stabilised by day 5 post-implantation and remained present during the whole observation period. Moreover, the increase in astrocyte density was associated with a high degree of astroglial scarring within and surrounding the graft site. During the two-week follow up in this study, the NSC graft site underwent extensive remodelling with NSC graft survival further declining to around 1% of the initial number of grafted cells.ConclusionsThe present study quantitatively describes the early post-transplantation events following NSC grafting in the adult mouse brain and warrants that such intervention is directly associated with a high degree of cell loss, subsequently followed by strong glial cell responses.

Transplantation of Enteric Neural Stem/Progenitor Cells into the Irradiated Young Mouse Hippocampus

“…Death of transplanted cells is a major hindrance for cell therapy (31), because of the small number of remaining cells to be incorporated, because of the local reaction caused by dying cells (55), and because of the structural changes incurred (48). Long-term studies have revealed a low yield of grafted cells over time (2,45). Likewise, 4 months after transplantation, the number of detectable ENSPCs was only 0.1%, indicating that death of grafted ENSPCs is an ongoing process.…”

Intracerebral transplantation of interleukin 13-producing mesenchymal stem cells limits microgliosis, oligodendrocyte loss and demyelination in the cuprizone mouse model

“…Lastly, transplantation of genetically engineered (stem) cell populations is an emerging methodological approach for in situ delivery of therapeutic proteins [9, 10]. Preceding work by our group has already extensively compared the in vivo behaviour of neural stem cell (NSC) and mesenchymal stem/stromal cell (MSC) grafts upon implantation in the CNS of mice [11–16]. Based on our published reports, we have a strong preference for MSC as a cellular carrier to deliver therapeutic proteins due to their relatively easy ex vivo culture, susceptibility for genetic modification and their more robust survival upon grafting in CNS tissue compared to NSC.…”

3D culture of murine neural stem cells on decellularized mouse brain sections

“…With our specific interest in cell and/or tissue transplantation research, we realize that general viability of our 3D NSC constructs still needs to be improved in order to limit endogenous immune response triggered by apoptotic and necrotic cells [6,38]. One such approach would be the manipulation of scaffold porosity via perforation in order to increase diffusion of oxygen/nutrients to the core of the decellularized brain tissue sections and to allow for improved cellular distribution [39].…”

“…However, despite the fact that neurospheres are easily cultured ex vivo, it is generally accepted these in vitro NSC populations are not fully representative for the spatiotemporal behaviour of NSC in vivo [3]. The substantial heterogeneity that occurs during neurosphere expansion [5,6], which in addition coincides with a high amount of apoptotic NSC/ NPC within the core of neurospheres [5], are features rarely found in the in vivo 3D NSC niche [7]. Nevertheless, 3D culture of NSC offers many benefits, ranging from dynamic growth processes to the creation of gradients, which resemble the in vivo situation [6,8,9] and are crucial in many biological processes [9,10].…”