LOS ANGELES, Nov. 28 (Xinhuanet) -- A breakthrough in stem cell research could eventually lead to cures for debilitating diseases such as Alzheimer's or Parkinson's, US scientists reported on Monday.

    According to the latest issue of the Proceedings of National Academy of Sciences, researchers now firmly believe that one day stem cells, by transmuting into healthy tissue cells to replace rotten ones, could become a remedy for the brain diseases.

    The claim has been made by researchers in American who found that human bone marrow stem cells might have more therapeutic potentials than previously thought. This is due to their capability of stimulating the differentiation of other stem cells.    

    Researchers from the Tulane University found that human bone marrow stem cells implanted into mouse brains stimulated the creation of differentiated neural cells.

    In the experiment, researchers implanted stem cells from human bone marrow into the dentate gyrus of the hippocampus of immuno deficient mice. The hippocampus is the part of the brain responsible for memory and navigation.

    The implanted human marrow stem cells markedly increased the proliferation of mice neural stem cells, the researchers found.

    Seven days after implantation, newly grown neuron cells were found to have migrated throughout the dorsal hippocampus of the mice's brains. By 30 days after implantation, the newly generated brain cells were showing signs of more mature neurons and astrocytes.

    In addition, groups of the newly grown mice brain cells exhibited elaborate processes of immuno reactive ciliary neurotrophic factors and nerve growth factors.

    "Therefore, implantation of human bone marrow stem cells stimulated proliferation, migration, and differentiation of the endogenous neural stem cells that survived as differentiated neural cells," the researchers said in the paper.

    The results may explain recent observations in which stem cells derived from bone marrow or related tissues were found to improve therapeutic effects of other stem cells, said the research team.

    The effects produced by the human bone marrow stem cells were probably explained by their secretion of chemokines, suggested the researchers led by Professor Darwin Prockop. After implantation, there was a general increase of different chemokines in the mice's hippocampus, they found.

    Chemokines are a family of glycoproteins with potent leukocyte activation and chemotactic activity. But the researchers indicated that those chemokines from human marrow stem cells probably accounted for the increase in mice neuron cells.

    It is also possible that factors secreted by the human bone marrow stem cells activated nearby astrocytes, which in turn stimulated neuron cell growth, said the researchers.

    Embryonic stem cells or other tissue stem cells, if implanted together with bone marrow stem cells, were capable of differentiating more efficiently, the researchers noted. Enditem