GAP43-dependent mitochondria transfer from astrocytes enhances glioblastoma tumorigenicity.

The transfer of intact mitochondria between heterogeneous cell types has been confirmed in various settings, including cancer. However, the functional implications of mitochondria transfer on tumor biology are poorly understood. Here we show that mitochondria transfer is a prevalent phenomenon in glioblastoma (GBM), the most frequent and malignant primary brain tumor. We identified horizontal mitochondria transfer from astrocytes as a mechanism that enhances tumorigenesis in GBM. This transfer is dependent on network-forming intercellular connections between GBM cells and astrocytes, which are facilitated by growth-associated protein 43 (GAP43), a protein involved in neuron axon regeneration and astrocyte reactivity. The acquisition of astrocyte mitochondria drives an increase in mitochondrial respiration and upregulation of metabolic pathways linked to proliferation and tumorigenicity. Functionally, uptake of astrocyte mitochondria promotes cell cycle progression to proliferative G2/M phases and enhances self-renewal and tumorigenicity of GBM. Collectively, our findings reveal a host-tumor interaction that drives proliferation and self-renewal of cancer cells, providing opportunities for therapeutic development.

[Neuroprotective effects of exogenous basic fibroblast growth factor on the hypoxic-ischemic brain damage of neonatal rats].

OBJECTIVE: To investigate the neuroprotective effect of basic fibroblast growth factor (bFGF) on neurological function after hypoxic-ischemic brain damage (HIBD) in neonatal rats. METHODS: Ninety-six HIBD models of neonatal Wistar rats were made by shearing right arteria carotis communis and then breathing 8% O(2)+92%N(2) for two hours. The models were divided into two groups randomly: the bFGF trial group and the normal saline control group. Each group had forty-eight rats. The other forty-eight neonatal Wistar rats were taken into the sham operation group. Forty rats were taken from each group and sacrificed on the 4 th, 7 th, 10 th, 17 th and 24 th days after the operation, respectively, The pathological changes in the brain were observed by optical microscope and the expressions of nestin and growth-associated protein-43 (GAP-43) in hippocampal CA1 region were examined with immunohistochemical staining and image quantitative analysis on the 4 th, 7 th, 10 th, 17 th and 24 th days after the operation. The spatial cognitive capability of other eight rats which were taken from each group respectively was evaluated by using the Morris water maze at the age of 30 days. RESULTS: (1) No brain damage was found in the sham operation group, the neurocytes were degenerative and necrotic in the control group of normal saline. The pathological manifestation of the brain damage in the bFGF trial group was milder than that of the normal saline control group. (2) Expression of nestin: The number of nestin-positive cells in hippocampal CA1 region of control group on the 4 th, 7 th, 10 th, 17 th and 24 th days after the operation was significantly increased compared with that of the sham operation group at all time points, and the numbers of nestin-positive cells in hippocampal CA1 region of the trial group were higher than those of the sham operation group and the control group (P < 0.01). (3) The expression of GAP-43 in hippocampal CA1 region of the neonatal rats reached peak on the 10th day after the operation in all the three groups. The integral optical density (IOD) of GAP-43 in hippocampal CA1 region of the control group was higher than that of the sham-operation group at all time points, and the IOD of GAP-43 in hippocampal CA1 region of the trial group was higher than those of the sham operation group and the control group at all time points (P < 0.01 for all). (4) The latency to escape platform in control group (51.75 +/- 11.27s) was longer than that in trial group (40.32 +/- 11.48s) and the sham operation group (36.58 +/- 10.83s) (P < 0.05); the frequency of passing through the platform in control group (2.34 +/- 2.42) was less than that in trial group (5.08 +/- 3.86) and the sham operation group (7.03 +/- 3.62) (P < 0.05). There was no significant difference between the trial group and the sham operation group (P > 0.05). CONCLUSIONS: (1) The expression of nestin and GAP-43 increased in hippocampal CA1 region of neonatal rats with HIBD, it may be involved in the activation of neural stem cells and the regeneration of neurocytes after HIBD. (2) The treatment with bFGF can improve the ability of learning and memory of neonatal rats with HIBD. (3) Exogenous bFGF could enhance the expression of nestin and GAP-43 in the brain of neonatal rats with HIBD, which may play an important role in restoration of neurons damaged due to hypoxia-ischemia.

Growth factors and stem cells as treatments for stroke recovery.

Both polypeptide growth factors and stem cell populations from bone marrow and umbilical cord blood hold promise as treatments to enhance neurologic recovery after stroke. Growth factors may exert their effects through stimulation of neural sprouting and enhancement of endogenous progenitor cell proliferation, migration, and differentiation in brain. Exogenous stem cells may exert their effects by acting as miniature "factories" for trophic substances in the poststroke brain. The combination of growth factors and stem cells may be more effective than either treatment alone. Stroke recovery represents a new and relatively untested target for stroke therapeutics. Whereas acute stroke treatments focus on agents that dissolve blot clots (thrombolytics) and antagonize cell death (neuroprotective agents), stroke recovery treatments are likely to enhance structural and functional reorganization (plasticity) of the damaged brain. Successful clinical trials of stroke recovery-promoting agents are likely to be quite different from trials testing acute stroke therapies. In particular, the time window of effective treatment to enhance stroke recovery is likely to be far longer than that for acute stroke treatments, perhaps days or weeks rather than minutes or hours after stroke. This longer time window means that time is available for careful screening and testing of potential subjects for stroke recovery trials, both in terms of size and location of cerebral infarcts and in type and severity of neurologic deficits. Detailed baseline information can be obtained for each patient against which eventual clinical outcome can be compared. Finally, separate and detailed outcome measures can be obtained in both the sensorimotor and cognitive neurologic spheres, because it is possible that these two kinds of function may recover differently or be differentially responsive to recovery-promoting treatments. Stroke recovery represents an important and underexplored opportunity for the development of new stroke treatments.