[Effects of let-7a on proliferation, osteogenic differentiation and apoptosis of human dental pulp stem cells].

PURPOSE: To study the effect and possible mechanism of let-7a on proliferation, differentiation and apoptosis of human dental pulp stem cell (hDPSCs). METHODS: The cells were divided into four groups: overexpression control (let-7a control/let-7a agomir control), overexpression let-7a (let-7a mimics/let-7a agomir), knockdown let-7a control (let-7a inhibitor control) and knockdown let-7a (let-7a inhibitor). Cell counting kit-8 assay(CCK-8) was used to detect the proliferation of cells at 24 hours, 48 hours and 72 hours after transfection. Calcified nodules were detected by Alizarin red staining. The protein expression of alkaline phosphatase (ALP), osteopontin (OPN), 4E-binding protein 1 (4EBP1), p-4EBP1, mammalian target of rapamycin (mTOR) and p-mTOR were detected by Western blot. Annexin V-APC/7-AAD cell apoptosis detection kit was used to detect the level of apoptosis after transfection. Statistical analysis was performed using GraphPad Prism 5.0 software. RESULTS: Let-7a inhibited proliferation of hDPSCs and promoted odontoblast differentiation and apoptosis. Let-7a down-regulated the expression of 4EBP1, p-4EBP1, mTOR and p-mTOR. CONCLUSIONS: Let-7a may inhibit proliferation of hDPSCs and promote their differentiation and apoptosis by inhibiting mTOR-4EBP1 molecular pathway.

Transplantation of adipocyte-derived stem cells in a hydrogel scaffold for the repair of cortical contusion injury in rats.

Adipocyte-derived stem cells have emerged as a novel source of stem cell therapy for their autologous and readily accessible and pluripotent potential to differentiate into different lineages such as neural stem cells (NSCs) and endothelial progenitor cells (EPCs). Transplantation of NSCs and EPCs has been promising for the repair of brain injury. We explored using co-transplanted hydrogel scaffold to improve the survival of the transplanted cells and recovery of neurological function. Adult Wistar rats were transplanted with EPC-hydrogel, NSC-hydrogel, NSC-EPC-hydrogel, EPC only, or NSC only 7 days after cortical contusion injury. Behavioral tests were performed to evaluate neurological function before, and 1, 2, 3, and 4 weeks after transplantation. Size of injury, extent of vascularization, as well as the survival and differentiation of the transplanted EPCs and NSCs, were evaluated at week 5. All transplantation groups displayed significantly better neurological function compared with the control groups. Improved neurological function correlated with significantly smaller injury volumes than that of the saline group. Using immunostaining, we have shown that while transplanted NSCs differentiated into both neurons and astrocytes, the EPCs were incorporated into vessel epithelia. The extent of reactive gliosis (based on glial fibrillary acidic protein immunostaining) was significantly reduced in all treatment groups (NSC-EPC-hydrogel, NSC-hydrogel, and EPC-hydrogel) when compared with the saline group, with the highest reduction in the NSC-EPC-hydrogel transplantation group. Thus, co-transplantation of hydrogel scaffold provides a more conducive environment for the survival and differentiation of NSCs and EPCs at the site of brain injury, leading to improved vascularization and better recovery of neurological function.

[Responses of neurons and astrocytes in rat hippocampus to kainic acid-induced seizures].

OBJECTIVE: To investigate the time course of the responses of neurons and astrocytes in rat hippocampus (HI) to kainic acid (KA)-induced seizures in various regions. METHODS: By means immunohistochemical staining for anti-Fos protein and anti-glial fibrillary acidic protein (GFAP), the regional distribution of reactive neurons and astrocytes in the HI was observed at different time points after a unilateral stereotaxic microinjection of KA into the lateral ventricle of rats to cause limbic and generalized convulsive seizures. RESULTS: The injection of KA triggered limbic motor seizures including immobilization, staring, facial and jaw clonus ect. followed by recurrent generalized convulsive seizures. After KA-induced seizures, the GFAP-positive astrocytes and Fos-positive neurons were markedly increased in the HI. The increase of GFAP immunoreactivity was observed 30 min after the seizure onset, reaching the maximum at 1 h; the increase of Fos immunoreactivity was detected at 1 h after the onset, peaking at 2 h. CONCLUSION: The neurons and astrocytes in rat HI are highly active during seizures and the reactive astrocytes might play an important role in epileptogenesis.