Ming Feng

Transplantation of human bone marrow-derived mesenchymal stem cells promotes behavioral recovery and endogenous neurogenesis after cerebral ischemia in rats

Mesenchymal stem cells (MSCs) have been successfully used for the treatment of experimental stroke. However, the neurorestorative mechanisms by which MSCs improve neurological functional recovery are not fully understood. Endogenous cell proliferation in the subventricular zone (SVZ) after stroke is well known, but most of newly formed cells underwent apoptosis. In the present study, we tested the hypothesis that neurotrophic factors secreted by human bone marrow-derived MSCs (hBMSCs) promote endogenous neurogenesis, reduce apoptosis, and improve functional recovery. Adult rats subjected to 2-h middle cerebral artery occlusion (MCAO) were transplanted with hBMSCs or saline into the ipsilateral brain parenchyma at 3days after ischemia. There was a significant recovery of behavior in the hBMSCs-treated rats beginning at 14days after MCAO compared with the control animals. Higher levels of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and vascular endothelial growth factor (VEGF) were detected in the hBMSCs-treated rat brain than the control. Human BMSCs treatment also enhanced endogenous cell proliferation both in the SVZ and in the subgranular zone (SGZ) of the hippocampus. In addition, more neuronal progenitor cells migrated from the SVZ to the ischemic boundary zone (IBZ) and differentiated into mature neurons with less apoptosis in rats treated with hBMSCs. Overall, these data suggest an essential role for hBMSCs in promoting endogenous neurogenesis, protecting newly formed cells, and improving functional recovery after ischemia in rats.

Human mesenchymal stem cell transplantation protects against cerebral ischemic injury and upregulates interleukin-10 expression in Macacafascicularis

Mesenchymal stem cell (MSC) transplantation has been reported to improve neurologic function after ischemic injury. However, the detailed mechanisms by which MSCs promote functional recovery are not fully understood. Interleukin-10 (IL-10) is a well-known anti-inflammatory cytokine with neuroprotective effects with respect to brain injury. In this study, a non-human primate ischemia model was used to test the hypothesis that transplanted human bone-marrow-derived MSCs (hBMSCs) exert a neuroprotective effects on cerebral ischemia and upregulate IL-10 expression. We also assessed neuronal apoptosis and astroglial activity in the area around the ischemic lesion and proliferating cells in the subventricular zone (SVZ). Results showed that hBMSC transplantation in ischemic tissues improved the neurological functions and induced an increase in IL-10 expression. In addition, neuronal apoptosis and astroglial activity in the peri-ischemic area decreased, and the number of proliferating cells in the SVZ increased. These results provide a novel therapeutic strategy for improving neurologic function after cerebral ischemia.

Transplantation of Flk‐1+ human bone marrow‐derived mesenchymal stem cells promotes angiogenesis and neurogenesis after cerebral ischemia in rats

Transplantation of bone marrow‐derived mesenchymal stem cells (BMSCs) is a potential therapy for cerebral ischemia. Although BMSCs‐induced angiogenesis is considered important for neurological functional recovery, the neurorestorative mechanisms are not fully understood. We examined whether BMSCs‐induced angiogenesis enhances cerebral tissue perfusion and creates a suitable microenvironment within the ischemic brain, which in turn accelerates endogenous neurogenesis and leads to improved functional recovery. Adult female rats subjected to 2 h middle cerebral artery occlusion (MCAO) were transplanted with a subpopulation of human BMSCs from male donors (Flk‐1+ hBMSCs) or saline into the ipsilateral brain parenchymal at 3 days after MCAO. Flk‐1+ hBMSCs‐treated rats exhibited significant behavioral recovery, beginning at 2 weeks after cerebral ischemia compared with controls. Moreover, rats treated with Flk‐1+ hBMSCs showed increased glucose metabolic activity and reduced infarct volume. Flk‐1+ hBMSCs treatment significantly increased the expression of vascular endothelial growth factor and brain‐derived neurotrophic factor, promoted angiogenesis, and facilitated cerebral blood flow in the ischemic boundary zone. Further, Flk‐1+ hBMSCs treatment enhanced proliferation of neural stem/progenitor cells (NSPCs) in the subventricular zone and subgranular zone of the hippocampus. Finally, more NSPCs migrated toward the ischemic lesion and differentiated to mature neurons or glial cells with less apoptosis in Flk‐1+ hBMSCs‐treated rats. These data indicate that angiogenesis induced by Flk‐1+ hBMSCs promotes endogenous neurogenesis, which may cause functional recovery after cerebral ischemia.

Intra-arterial delivery of human bone marrow mesenchymal stem cells is a safe and effective way to treat cerebral ischemia in rats.

Cerebral ischemic stroke is a very common condition that can cause death and disability. Studies have confirmed that stem cells have therapeutic effects if administered after a stroke. There is still a great deal of debate regarding the best route for cell transplantation. Intravascular delivery is the most commonly used one. In this study, the therapeutic effects of bone marrow stem cells (BMSCs) delivered by intra-arterial (IA) and intravenous (IV) injection in a rat transient middle cerebral artery occlusion model (MCAO) are compared. Histological analysis demonstrated that the IA route bypasses the pulmonary system and directs the cells to the ischemic parts of the brain more efficiently. The BMSCs delivered via the IA route promoted angiogenesis and improved functional recovery. The cerebral blood flow (CBF) of the rats was monitored during the IA injection process. No reduction in CBF or microstrokes was detected. Brain perfusion and metabolism, as evaluated by SPECT and PET, were better in rats treated with cells delivered via IA. Results showed that the IA route is a safe and effective way to transplant hBMSCs. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.

Pyrimethamine sensitizes pituitary adenomas cells to temozolomide through cathepsin B-dependent and caspase-dependent apoptotic pathways.

Invasive pituitary adenomas (PAs) are generally refractory to conventional therapy and salvage treatment with temozolomide (TMZ). In addition to antiprotozoan effects, pyrimethamine (PYR) has recently shown its strong antitumor activity as an antineoplastic agent or in combination with TMZ in metastatic melanoma cells. In this study, the effects of TMZ, PYR or TMZ/PYR combination on rat/mouse PA cell lines αT3‐1, GH3, MMQ and ATt‐20 as well as GH3 xenograft tumor model were evaluated. TMZ/PYR combination synergistically inhibited proliferation, invasion and induced apoptosis of these PA cell lines in vitro. Strikingly, combination treatment with TMZ and PYR produced synergistic antitumor activity and enhanced the survival rate of GH3 xenograft tumor models without increasing systemic side effects. In addition, TMZ/PYR induced cell cycle arrest, increased DNA damage, upregulated the expression of cathepsin B, BAX, cleaved PARP and phosphorylated histone H2AX as well as elevated caspase3/7, 8 and 9 activities. The decreased expression of Bcl‐2, MMP‐2 and MMP‐9 alone with cytochrome c release from mitochondria into the cytosol was also observed in the TMZ/PYR combination group. The increase in cell apoptosis due to combination with PYR was rescued by leucovorin. These data suggest that PYR may enhance the efficacy of TMZ via triggering both cathepsin B‐dependent and caspase‐dependent apoptotic pathways. Therefore, combination of PYR and TMZ may provide a novel regimen for invasive PAs refractory to standard therapy and TMZ.

Screening for AIP gene mutations in a Han Chinese pituitary adenoma cohort followed by LOH analysis

OBJECTIVE The aryl hydrocarbon receptor interacting protein gene (AIP) is associated with pituitary adenoma (PA). AIP has not been sequenced in East Asian PA populations, so we performed this study in a Han Chinese cohort. DESIGN Our study included six familial PA pedigrees comprising 16 patients and 27 unaffected relatives, as well as 216 sporadic PA (SPA) patients and 100 unrelated healthy controls. METHODS AIP sequencing was carried out on genomic DNA isolated from blood samples. Multiplex ligation-dependent probe amplification and microsatellite marker analyses on DNA from the paired tumor tissues were performed for loss of heterozygosity analysis. RESULTS We identified three common and four rare single nucleotide polymorphisms (SNPs), one intron insertion, one novel synonymous variant, four novel missense variants, and a reported nonsense mutation in three familial isolated PA (FIPA) cases from the same family. Large genetic deletions were not observed in the germline but were seen in the sporadic tumor DNA from three missense variant carriers. The prevalence of AIP pathogenic variants in PA patients here was low (3.88%), but was higher in somatotropinoma patients (9.30%), especially in young adults (≤30 years) and pediatric (≥18 years) paients (17.24% and 25.00% respectively). All AIP variant patients suffered from macroadenomas. However, the AIP mutation rate in FIPA families was low in this cohort (16.67%, 1/6 families). CONCLUSION AIP gene mutation may not be frequent in FIPA or SPA from the Han Chinese population. AIP sequencing and long-term follow-up investigations should be performed for young patients with large PAs and their families with PA predisposition.

Antiproliferative, Antiinvasive, and Proapoptotic Activity of Folate Receptor α-Targeted Liposomal Doxorubicin in Nonfunctional Pituitary Adenoma Cells

There is an urgent need for novel therapeutic strategies for the treatment of nonfunctional pituitary adenomas (NFPAs), especially those that are invasive. The folate receptor (FR)α is overexpressed in several cancers, including NFPA. The aim of this study was to determine the efficacy of FRα-targeted liposomes loaded with doxorubicin (F-L-DOX) in the treatment of NFPA. We evaluated targeting, cytotoxicity, antiinvasive, and proapoptotic activity of F-L-DOX in 25 primary cell lines derived from patients with NFPAs. We found that these liposomes effectively targeted NFPA cells through FRα and that endocytosis of the liposomes was blocked by 1mM free folic acid. F-L-DOX inhibited proliferation of NFPA cells and promoted apoptosis through activation of caspase-8, caspase-9, and caspase-3/7 more effectively than L-DOX. Furthermore, F-L-DOX also exerted greater antiinvasive ability in NFPA cells than L-DOX through suppression of the secretion of matrix metalloproteinase-2 and matrix metalloproteinase-9. Addition of 1mM free folic acid significantly reduced the pleotropic effects of F-L-DOX in NFPA cells, suggesting that FRα plays a critical role in mediating the antitumor effect of F-L-DOX. Our findings warrant further investigation of F-L-DOX as an alternative therapeutic strategy for the treatment of NFPAs that express FRα.

Transplantation of Flk-1+ human bone marrow-derived mesenchymal stem cells promotes behavioral recovery and anti-inflammatory and angiogenesis effects in an intracerebral hemorrhage rat model

Mesenchymal stem cells (MSCs) have been successfully used for the treatment of experimental intracerebral hemorrhage (ICH). However, the neuroprotective mechanisms through which MSCs improve neurological functional recovery are not fully understood. In the present study, we tested the hypothesis that treatment with MSCs inhibits inflammation after ICH and reduces subsequent brain injury. Adult rats subjected to stereotaxic injection of collagenase VII were transplanted with a subpopulation of human bone marrow-derived MSCs (hBMSCs), termed fetal liver kinase (Flk)-1(+) hBMSCs, or saline into the ipsilateral brain parenchyma 1 day after ICH. Significant recovery of behavior was noted in the Flk-1(+) hBMSC-treated rats beginning 3 days after ICH compared with the control group. Brain water content was significantly decreased in the ipsilateral hemispheres of the Flk-1(+) hBMSC-treated rats when compared with the controls 3 days after ICH. The relative hemorrhage volume was reduced 55 days after Flk-1(+) hBMSC treatment. However, this change was not statistically significant. Flk-1(+) hBMSCs significantly inhibited the proliferation of rat peripheral blood mononuclear cells (rPBMCs) induced in a mixed lymphocyte reaction. Consistently, we found a significant anti-inflammatory effect of Flk-1(+) hBMSCs on the ICH brain, including a decrease in neutrophil infiltration and microglial activation in the peri-ICH area, and downregulation of inflammatory mediators, such as interleukin (IL)-1β, IL-2, IL-4, IL-6, and tumor necrosis factor (TNF)-α. In addition, Flk-1+ hBMSC treatment significantly increased vascular density in the peri-ICH area, and transplanted Flk-1(+) hBMSCs were found to be incorporated into the cerebral vasculature 55 days after transplantation. Overall, these data suggest an essential role for Flk-1(+) hBMSCs in reducing inflammatory infiltration, promoting angiogenesis, and improving functional recovery after ICH in rats.

O-6-Methylguanine-DNA methyltransferase expression is associated with pituitary adenoma tumor recurrence: a systematic meta-analysis

O-6-methylguanine-DNA methyltransferase (MGMT) reportedly counteracts the cytotoxic effects of the alkylating agent temozolomide. MGMT expression is often low in aggressive pituitary adenomas (PAs) and recurrent PAs. However, because these associations are controversial, we performed this meta-analysis to clarify the involvement of MGMT in the prognosis and clinicopathology of PA. We searched for relevant studies in electronic databases (MEDLINE, the Cochrane Library Database, EMBASE, CINAHL, Web of Science and the Chinese Biomedical Database (CBD)) and calculated/pooled the odds ratios (ORs) or standard mean differences (SMDs) with 95% confidence intervals (95% CIs). Eleven case-control studies with a total of 454 PA patients were included. Our meta-analysis revealed that lower expression of MGMT was associated with PA recurrence (OR=2.09, 95% CI=1.09–4.02; p=0.026). On the other hand, MGMT expression was not associated with PA invasiveness (OR=1.112, 95% CI=0.706–1.753; p=0.646), Unexpectedly, MGMT expression could not be used to distinguish functional from non-functional PA patients (OR=1.766, 95% CI=0.938–3.324; p=0.078). The MGMT expression was not found to be related to other clinicopathological indicators of PA including age, gender or tumor size. No publication bias was detected in this meta-analysis (p>0.05). This meta-analysis suggests that MGMT expression may be associated with PA tumor recurrence, but not be related to invasiveness or other clinicopathological indicators. Thus, detection of MGMT expression may facilitate outcome prediction and guide clinical therapy for PA patients.

Refractory pituitary adenoma: a novel classification for pituitary tumors

Pituitary adenomas are classified as typical or atypical, invasive or noninvasive, and aggressive or nonaggressive based on pathological features, radiological findings, and clinical behavior. Only pituitary tumors with cerebrospinal and/or systemic metastasis are considered malignant carcinomas. However, some pituitary adenomas with high Ki-67 indexes exhibit aggressive behaviors, such as rapid growth, early and frequent recurrence, and resistance to conventional treatment, even in the absence of metastasis. Novel terminology is needed to define these tumors. Here, we propose the use of the term “refractory pituitary adenoma” to define malignant pituitary tumors exhibiting 1) a high Ki-67 index and rapid growth, 2) early and high frequency of recurrence, 3) resistance to conventional treatments and/or salvage treatment with temozolomide (TMZ), 4) poor prognosis, 5) and a lack of cerebrospinal or systemic metastases. To illustrate the utility of this refractory pituitary adenoma classification and the difficulty in managing disease in these patients, we examined twelve clinical cases. Correctly identifying refractory pituitary adenomas is crucial for improving patient prognoses. Early identification might encourage the early use of aggressive therapeutic strategies to prevent or delay recurrence.