Antibodies isolating and/or identifying neuronal stem cells and method for isolating and/or identifying neuronal progenitor cells

Patent Number: 7,182,946

Methods of purifying stem cells, as well as progenitor cell populations are well known in the art. Unfortunately, some of these methods have certain limitations, and as a result, there is always a great need to identify new ways of sometimes doing the same thing. For example, it is known that CD34 is a useful marker for hematopoietic stem cells. However, since the patent on CD34 has a limited life, newer methods of identifying cells expressing CD34 are being patented, such as detection of stem cells by aldehyde dehydrogenase activity. In the area of neural stem cells, there are patents on purifying such cells using markers like CD133. In the current patent a novel antibody for detecting neural stem cells is disclosed. The cells purified by this antibody also express CD56, CD90, CD133, W4A5, W6D3 (CD15), W8C3 and lack expression of CD45, CD10, W7C5 (CD109) and W8B2.

This patent claims the composition of matter for the hybridoma 57D2, as well as the antibody and fragments of antibody generated by the hybridoma. Compositions of matter covered also include the antibody together with a diluent, a carrier, and/or a stabilizing agent. Additionally, it covers both methods of identifying and methods of isolating neural progenitor cells using this antibody.

The patent background is interesting in that it provides some useful points for people interested in the area of neural stem cells. For example, a paper (Rao MS Anat Rec: 257:137-143, 1999) is discussed in which two classes of pluripotent neural stem cells are mentioned. The first class are neuroepithelial stem cells, and the second are EGF-dependent neurosphere stem cells. Both of these cell types were isolated from various regions of the brain including the hippocampus, the temporal area, as well as the frontal area. Also mentioned in the application is a paper by Barami et al (Neurol. Res. 23: 321 326 (2001)) which discloses that neural progenitor cells can be obtained from second trimester human CNS tissue by selection for CD133. This is important since CD133 is found on numerous other types of stem cells in addition to neural stem cells. Interestingly, Barami et al were able to induce differentiation of the CD133 positive cells into neurons and astrocytes by addition of factors such as EGF, FGF, and LIF. The patent states that since CD133 is found in numerous other stem cells, it is not a suitable marker for neural stem cell isolation. The difficulty in identifying means of purifying neural stem cells is compounded by the fact that mesenchymal stem cells have similar morphology and phenotype as neural stem cells. To support this point the patent provided several references. For example 2 papers (Kopen et al. PNAS, 96: 10711, (1999) and Brazelton et al. Science 290: 1775 1779 (2000), demonstrated that bone marrow mesenchymal stem cells can differentiate into neural cells, and also had similar phenotypic properties as neural stem cells. The patent also states that the currently used marker, nestin, for differentiating neural stem cells from other types of stem cells is not ideal since nestin is also expressed on astrocytes (Clarke et al. Neuroreport 5: 1885 1888 (1994)), as well as skeletal muscle cells (Sejersen and Lendahl J. Cell Sci. 106: 1291 1300 (1993)).

View this patent on the USPTO website.