Stem cells have emerged as a potential therapy for a range of neural insults, but their application in Alzheimer's disease (AD) is still limited and the mechanisms underlying the cognitive benefits of stem cells remain to be elucidated. Here, the effects of clinical‐grade human umbilical cord‐derived mesenchymal stem cells (hUC‐MSCs) on the recovery of cognitive ability in SAMP8 mice, a senescence‐accelerated mouse model of AD is explored. A functional assay identifies that the core functional factor hepatocyte growth factor (HGF) secreted from hUC‐MSCs plays critical roles in hUC‐MSC‐modulated recovery of damaged neural cells by down‐regulating hyperphosphorylated tau, reversing spine loss, and promoting synaptic plasticity in an AD cell model. Mechanistically, structural and functional recovery, as well as cognitive enhancements elicited by exposure to hUC‐MSCs, are at least partially mediated by HGF in the AD hippocampus through the activation of the cMet‐AKT‐GSK3β signaling pathway. Taken together, these data strongly implicate HGF in mediating hUC‐MSC‐induced improvements in functional recovery in AD models.

Cognitive aging is a leading public health concern with the increasing aging population, but there is still lack of specific interventions directed against it. Recent studies have shown that cognitive function is intimately affected by systemic milieu in aging brain, and improvement of systemic environment in aging brain may be a promising approach for rejuvenating cognitive aging. Here, we sought to study the intervention effects of clinical-grade human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) on cognitive aging in a murine model of aging. The conventional aging model in mice induced by d-galactose (d-gal) was employed here. Mice received once every two weeks intraperitoneal administration of hUC-MSCs. After 3 months of systematical regulation of hUC-MSCs, the hippocampal-dependent learning and memory ability was effectively improved in aged mice, and the synaptic plasticity was remarkably enhanced in CA1 area of the aged hippocampus; moreover, the neurobiological substrates that could impact on the function of hippocampal circuits were recovered in the aged hippocampus reflecting in: dendritic spine density enhanced, neural sheath and cytoskeleton restored, and postsynaptic density area increased. In addition, the activation of the endogenic neurogenesis which is beneficial to stabilize the neural network in hippocampus was observed after hUC-MSCs transplantation. Furthermore, we demonstrated that beneficial effects of systematical regulation of hUC-MSCs could be mediated by activation of mitogen-activated protein kinase (MAPK)-ERK-CREB signaling pathway in the aged hippocampus. Our study provides the first evidence that hUC-MSCs, which have the capacity of systematically regulating the aging brain, may be a potential intervention for cognitive aging.

Human embryonic stem (hES) cells can self-renew, which enables them to have considerable expansion potential, and are pluripotent. If their differentiation can be controlled, they can offer promise for clinical programs in cell therapies. A novel strategy has been developed to derive early hepatocytic lineage stages from hES cells using four sequential inducing steps lasting 16 days. First, embryoid bodies (EBs) were generated by growing hES cells in suspension for 2 days; second, EBs were lineage restricted to definitive endoderm with 3 days of treatment with human activin A; third, cells were differentiated further by coculturing for 5 days with human fetal liver stromal cells (hFLSCs) made transgenic to stably release basic fibroblast growth factor (bFGF); fourth, treating them for 6 days with soluble signals comprised of hFLSC-derived bFGF, hepatocyte growth factor, oncostatin M, and dexamethasone. Induced cells displayed morphological, immunohistochemical, and biochemical characteristics of hepatocytic committed progenitors and of early lineage stage hepatocytes found in zone 1 of the liver acinus. They expressed alpha-fetoprotein, albumin, cytokeratin 18, glycogen, a fetal P450 isoform, and CYP1B1, and demonstrated indocyanine green uptake and excretion. In conclusion, we have developed a novel method to lineage restrict hES cells into early lineage stages of hepatocytic fates.

Human adipose-derived stem cells (hASCs) have been shown to be multipotent and could be induced into various cell types, which make them the ideal cell source for cell therapy or tissue engineering. However, differentiation of ASCs into hepatocytes on three-dimensional scaffold, an important part of tissue engineering, has not been reported. In this study, to investigate the hepatogenesis of ASCs on porous poly-lactide-co-glycolide (PLGA) scaffolds, we loaded hASCs on these scaffolds. The cell-scaffold complex was implanted into the peritoneal cavity of 70% hepatectomized rats with or without 14 days of induction in hepatic inducing medium. Our results indicated that hASCs cultured on the PLGA scaffolds in the hepatic inducing medium proliferated more efficiently and could be induced into cells with hepatocyte-like phenotypic and functional properties. In vivo studies showed that induced hASCs on PLGA scaffolds survived and maintained hepatic phenotype and function for at least 14 days after implantation; moreover, noninduced hASCs on PLGA scaffolds expressed human albumin 14 days after transplantation. Collectively, these results suggest that porous PLGA scaffolds are suitable for the hepatogenesis of hASCs. These findings might be helpful in the application of hASC-based tissue engineering for liver disease therapy.

Cord blood (CB) is an attractive source of hematopoietic stem cells (HSCs) for hematopoietic cell transplantation. However, its application remains limited due to the low number of HSCs/progenitors in a single CB unit and its notoriously difficulty in expanding ex vivo. Here, we demonstrated that the human fetal liver sinusoidal endothelial cells engineered to constitutively express the adenoviral E4orf1 gene (hFLSECs-E4orf1) is capable of efficient expansion ex vivo for human CB hematopoietic stem and progenitor cells (HSPCs). Coculture of CD34+ hCB cells with hFLSECs-E4orf1 resulted in generation of substantially more total nucleated cells, CD34+CD38− and CD34+ CD38−CD90+ HSPCs in comparison with that of cytokines alone after 14 days. The multilineage differentiation potential of the expanded hematopoietic cells in coculture condition, as assessed by in vitro colony formation, was also significantly heightened. The CD34+ hCB cells amplified on hFLSECs-E4orf1 were capable of engraftment in vivo. Furthermore, hFLSECs-E4orf1 highly expressed hematopoiesis related growth factor and Notch receptors. Accordingly, the CD34+ hCB cells amplified on hFLSECs-E4orf1 exhibited Notch signaling activation. Taken together, our findings indicated that FLSECs may potentially be the crucial component of the microenvironment to support recapitulation of embryonic HSC amplification in vitro and allow identification of new growth factors responsible for collective regulation of hematopoiesis.