Long‐term fate of grafted hippocampal neural progenitor cells following ischemic injury

Abstract

The adult CNS has a very limited capacity to regenerate neurons after insult. To overcome this limitation, the transplantation of neural progenitor cells (NPCs) has developed into a key strategy for neuronal replacement. This study assesses the long-term survival, migration, differentiation, and functional outcome of NPCs transplanted into the ischemic murine brain. Hippocampal neural progenitors were isolated from FVB-Cg-Tg(GFPU)5Nagy/J transgenic mice expressing green fluorescent protein (GFP). Syngeneic GFP-positive NPCs were stereotactically transplanted into the hippocampus of FVB mice following a transient global cerebral ischemia model. Behavioral tests revealed that ischemia/reperfusion induced spatial learning disturbances in the experimental animals. The NPC transplantation promoted cognitive function recovery after ischemic injury. To study the long-term fate of grafted GFP-positive NPCs in a host brain, immunohistochemical approaches were applied. Confocal microscopy revealed that grafted cells survived in the recipient tissue for 90 days following transplantation and differentiated into mature neurons with extensive dendritic trees and apparent spines. Immunoelectron microscopy confirmed the formation of synapses between the transplanted GFP-positive cells and host neurons that may be one of the factors underlying cognitive function recovery. Repair and functional recovery following brain damage represent a major challenge for current clinical and basic research. Our results provide insight into the therapeutic potential of transplanted hippocampal progenitor cells following ischemic brain injury.

Maturation of neural stem cells and integration into hippocampal circuits – a functional study in an in situ model of cerebral ischemia

“…A broad therapeutic potential of stem cells has led to increasing interest in cell-based therapies for cell replacement strategies in neuronal cell loss after stroke, brain injury or in neurodegenerative diseases (Lindvall and Kokaia, 2015;Meamar et al, 2013;Pluchino et al, 2003;Kim et al, 2002). Such strategies include either transplantation of cells that are already differentiated into the injured tissue (Tornero et al, 2017;Kim et al, 2002) or engraftment of stem cells into a host tissue for subsequent differentiation and maturation (de la Rosa-Prieto et al, 2017;Tsupykov et al, 2014;Darsalia et al, 2011;Mine et al, 2013). The latter approach is considered as one promoting multipotent differentiation of neural precursors in an environment of endogenous cells in order to provide 'self-repair' of injured tissue (Gage, 2000), although such a concept remains debatable.…”

“…NSPCs were isolated from the hippocampi of 16-17 days post coitum (dpc) embryos from FVB-Cg-Tg(GFPU) 5Nagy/J transgenic mice expressing GFP (Tsupykov et al, 2014) by means of centrifugation (450 g, 10 min) of a cell suspension in 22% Percoll (GE Healthcare BioScience, Sweden). Flow cytometry was performed in the enriched cell fraction (5×10 5 cells in 100 µl phosphate-buffered saline, PBS) using the BD FACS Aria cell sorter with BD FACSDiva™ 6.1.2 software (BD Biosciences).…”

“…For visualization of synaptic structures between host cells and grafted NPSCs, immuno-electron microscopy was used as described in detail previously (Tsupykov et al, 2014). Briefly, slices were fixed with 4% PFA and 0.25% glutaraldehyde in 0.1 M PB for 1 h at room temperature.…”

“…Their therapeutic potential could be mediated by several mechanisms, namely via the acute trophic effects of stem cells on the injured tissue and their highpotent capability to differentiate into neural cells of either neuronal or glial types (Lindvall and Kokaia, 2015;Gage, 2000). In stroke-injured brain, neurons differentiated from stem cells incorporate into host circuitry (Tornero et al, 2017) and improve functional recovery (Mine et al, 2013;Tsupykov et al, 2014;Hicks et al, 2009;Oki et al, 2012). Independently of neuronal effects, neural stem/progenitor cells (NSPCs) and induced pluripotent stem cells (iPSCs) improve neurological function due to the neurotrophic effect derived from their differentiation into glial cells (predominantly, astroglia) (Emdad et al, 2012;Jiang et al, 2013).…”

Regenerative therapy for hippocampal degenerative diseases: lessons from preclinical studies

“…Besides, these drugs cause severe side‐effects ranging from psychological to cognitive to motor disturbances. Cell‐based therapy is emerging as a potential therapeutic alternative for treating various CNS diseases (Acharya et al ., ; Chen et al ., ; Garcia et al ., ; Liu et al ., ; Rosenblum et al ., ; Srivastava et al ., ; Tfilin et al ., ; Tsupykov et al ., ). Although in neurodegenerative diseases, such as amyotrophic lateral sclerosis and Parkinson's disease, hippocampal atrophy and memory impairments have been reported at the very advanced stages, early degeneration in the hippocampus is considered to be the principal cause of neurodegenerative diseases such as AD and TLE.…”