Isolation of a pluripotent neural stem cell from the embryonic bovine brain

Saikosaponin-d improved the stemness of mouse neural stem cells and increased their thermotolerance potential

PURPOSE

To investigate the effect of saikosaponin-d (Ssd) on proliferation, differentiation, and stemness of neural stem cells (NSCs), and to observe whether Ssd has a protective effect on NSCs at medium-high and high temperature.

MATERIALS AND METHODS

NSCs were extracted from 15-day fetal mice. After subculture, Ssd treatment was performed. Cell cycle and apoptosis rate were detected by flow cytometry. Western Blot and immunofluorescence assay were used to detect the expression and spatial distribution of Nestin, NSE, GFAP, Oct4, and SOX2. Cell growth morphology was observed under a microscope; the concentration of extracellular lactate dehydrogenase (LDH) was determined by ELISA.

RESULTS

Compared with the control group, the proportion of NSCs in the G0/G1 phase increased in the Ssd treatment group; on the contrary, the proportion in the G2/M phase significantly decreased. Microscopically, our results also suggested the sphere-formation rate increased significantly. Besides, the percentage of dead cells in the Ssd group at 38.5, 40°C were reduced, and the level of LDH release was dropped.

CONCLUSION

Ssd improved the stemness of NSCs, inhibited their differentiation into neural cells, and reduced cell damage under high temperature. Therefore, we speculate that Ssd can improve the thermotolerance of NSCs and protect the nervous system of children with fever.

Potential differentiation of islet-like cells from pregnant cow-derived placental stem cells

OBJECTIVE

Type 1 diabetes is an autoimmune disease that destroys islet cells and results in insufficient insulin secretion by pancreatic β-cells. Islet transplantation from donors is an approach used for treating patients with diabetes; however, this therapy is difficult to implement because of the lack of donors. Nevertheless, several stem cells have the potential to differentiate from islet-like cells and enable insulin secretion for treating diabetes in animal models. For example, placenta is considered a waste material and can be harvested noninvasively during delivery without ethical or moral concerns. To date, the differentiation of islet-like cells from cow-derived placental stem cells (CPSCs) has yet to be demonstrated.

MATERIALS AND METHODS

The investigation of potential differentiation of islet-like cells from CPSCs was conducted by supplementation with nicotinamide, exendin-4, glucose, and poly-d-lysine and was detected through reverse transcription polymerase chain reaction, dithizone staining, and immunocytochemical methods.

RESULTS

Our results indicated that CPSCs are established and express mesenchymal stem cell surface antigen markers, such as CD73, CD166, β-integrin, and Oct-4, but not hematopoietic stem cell surface antigen markers, such as CD45. After induction, the CPSCs successfully differentiated into islet-like cells. The CPSC-derived islet-like cells expressed islet cell development-related genes, such as insulin, glucagon, pax-4, Nkx6.1, pax-6, and Fox. Moreover, CPSC-derived islet-like cells can be stained with zinc ions, which are widely distributed in the islet cells and enable insulin secretion.

CONCLUSION

Altogether, islet-like cells have the potential to be differentiated from CPSCs without gene manipulation, and can be used in diabetic animal models in the future for preclinical and drug testing trial investigations.

Tissue-engineered nerve graft with tetramethylpyrazine for repair of sciatic nerve defects in rats

A tissue-engineered nerve with tetramethylpyrazine (TMP) was repaired for sciatic nerve defects in rats. A total of 55 adult Sprague Dawley (SD) rats were classified into 4 groups, with 15 rats in each of groups A, B, and C as well as 10 rats in group D. About 1.5cm of a sciatic nerve of the right hind limb located 0.5cm below the inferior margin of the piriformis was resected to form the defects. Four types of nerve grafts used for bridging nerve defects in the SD rats corresponded to the 4 groups: tissue-engineered nerves with TMP in group A, tissue-engineered nerves without TMP in group B, acellular nerve grafts (ANGs) in group C, and autologous nerves in group D. Twelve weeks post-surgery, the sciatic functional index, nerve conduction velocity, and gastrocnemius wet weight of groups A and D were higher than those of groups B and C (P<0.05). Results of fluorescence microscopy and histological staining indicated that group A performed better than groups B and C (P<0.05). Similarly, the number of horseradish peroxidase-labeled positive cells was significantly larger in group A than in groups B and C. Regenerative nerve fibers were abundant in group A and consisted mainly of myelinated nerve fibers, which were better than those in groups B and C (P<0.05). The study demonstrated that tissue-engineered nerves constructed by ANGs seeded with neural stem cells and combined with TMP can effectively repair sciatic nerve defects in rats.

Denervated hippocampus provides a favorable microenvironment for neuronal differentiation of endogenous neural stem cells

Fimbria-fornix transection induces both exogenous and endogenous neural stem cells to differentiate into neurons in the hippocampus. This indicates that the denervated hippocampus provides an environment for neuronal differentiation of neural stem cells. However, the pathways and mechanisms in this process are still unclear. Seven days after fimbria fornix transection, our reverse transcription polymerase chain reaction, western blot assay, and enzyme linked immunosorbent assay results show a significant increase in ciliary neurotrophic factor mRNA and protein expression in the denervated hippocampus. Moreover, neural stem cells derived from hippocampi of fetal (embryonic day 17) Sprague-Dawley rats were treated with ciliary neurotrophic factor for 7 days, with an increased number of microtubule associated protein-2-positive cells and decreased number of glial fibrillary acidic protein-positive cells detected. Our results show that ciliary neurotrophic factor expression is up-regulated in the denervated hippocampus, which may promote neuronal differentiation of neural stem cells in the denervated hippocampus.