System for the internal qualitative and quantitative validation of marker indices
View Patent ↗The present invention relates to the qualitative and quantitative validation of marker indices, especially for medical diagnosis and particularly for the determination of the growth fraction in a sample with antibodies against the Ki-67 protein. Diagnostic kit for the quantification of a cell fraction labeled by a marker for in vitro diagnosis, characterized in that a pseudo-tissue is used for the intra- and inter-assay standardization of the marker index.
1. A pseudo-tissue for the qualitative and quantitative validation of marker indices comprising a substantially homogeneous mixture of at least two different isolated cell populations fixed prior to incorporation in a matrix, wherein each said cell population comprises two or more cells that are substantially identical to each other with respect to the number of one or more specific marker(s), and said cell populations differ from each other with respect to the number of said one or more specific marker(s); and wherein the ratio between the cells of at least one of the cell populations and the cells of at least one different cell population is known.
2. The pseudo-tissue of claim 1 , wherein the marker is detectable by using an immunohistological, an immunocytological, and a hybridization technique.
3. The pseudo-tissue of claim 2 , wherein the immunohistological, the immunocytological, and the hybridization technique is an immunofluorescence technique.
4. The pseudo-tissue of claim 2 , wherein the immunohistological, the immunocytological, and the hybridization technique is an immunoenzymatic technique.
5. The pseudo-tissue of claim 1 , wherein the marker is a proliferation marker.
6. The pseudo-tissue of claim 5 , wherein the proliferation marker is Ki-67.
7. The pseudo-tissue of claim 1 , wherein the marker is a hormone receptor.
8. The pseudo-tissue of claim 7 , wherein the hormone receptor is selected from the group consisting of an estrogen receptor, a progesterone receptor and an androgen receptor.
9. The pseudo-tissue of claim 1 , wherein the marker is an oncogene product.
10. The pseudo-tissue of claim 9 , wherein the oncogene product is c-myc.
11. The pseudo-tissue of claim 1 , wherein the marker is a chromosomal aberration.
12. The pseudo-tissue of claim 11 , wherein the chromosomal aberration is selected from the group consisting of a gene amplification, a gene deletion, a point mutation and a translocation.
13. The pseudo-tissue of claim 1 , wherein the cells in at least one of the at least two cell populations are cells that have been cultured, collected and/or harvested in vitro.
14. The pseudo-tissue of claim 13 , wherein said cells of at least one of the cell populations are transfected.
15. The pseudo-tissue of claim 13 , wherein said cells of at least one of the cell populations are substantially identical to each other with respect to the number of one or more specific marker(s).
16. The pseudo-tissue of claim 15 , wherein said substantially identical cells are of a single cell line.
17. The pseudo-tissue of claim 1 , wherein a ratio between cells of the at least one cell population and the cells of the at least one different cell population in the substantially homogenous cell mixture is from 1:10 9 to 10 9 :1.
18. The pseudo-tissue of claim 1 , wherein a ratio between cells of the first cell population and cells of the second cell population in the substantially homogenous cell mixture is from 1:20 to 20:1.
19. The pseudo-tissue of claim 1 , wherein the matrix is selected from the group consisting of a plastic, a paraffin, a paraffin derivative, an agarose, a non-heparinized serum, a collagen, a cellulose derivative, a chitin derivative, and a chitosan derivative.
20. The pseudo-tissue tissue of claim 1 , wherein said fixation is performed using one or more fixatives selected from the group consisting of a formalin, a glutaraldehyde, an osmium tetraoxide, an acetic acid, an ethanol, an acetone, a picric acid, a chloroform, a potassium dichromate and a mercuric chloride fixative.
21. The pseudo-tissue of claim 1 , wherein at least one of the one or more specific markers is a marker for intra- and inter-assay standardization.
22. The pseudo-tissue of claim 1 , wherein at least one of the one or more specific markers is a CD-characterized cell membrane structure.
23. The pseudo-tissue of claim 1 , wherein said cells of at least two different cell populations are stabilized prior to fixation, wherein said stabilization is at least one member selected from the group consisting of a microwave heating stabilization and a freezing stabilization.
24. The pseudo-tissue of claim 1 , wherein the marker is a hematological marker.
25. The pseudo-tissue of claim 1 , wherein the marker is a cell membrane constituent.
26. The pseudo-tissue of claim 1 , wherein the marker is a nuclear bound receptor.
27. The pseudo-tissue of claim 1 , wherein the marker is an infectious agent.
28. A method for the production of a pseudo-tissue, comprising the steps of:
(a) selecting a first isolated cell population that comprises cells that are substantially identical to each other with respect to the number of one or more specific marker(s);
(b) selecting at least one additional isolated cell population that comprises cells that are substantially identical to each other with respect to the number of one or more specific marker(s), wherein said cells of said additional cell population differ from the cells of said first cell population with respect to one or more of said specific marker(s);
(c) mixing the first cell population with the additional cell population to thereby form a substantially homogeneous cell mixture, wherein the ratio between the cells of the first cell population and cells of the additional cell population is known; and
(d) incorporating the substantially homogeneous cell mixture into a matrix to thereby form the pseudo-tissue, wherein said cells of the first cell population and the additional cell population are fixed prior to or after forming the cell mixture and prior to incorporation into the matrix.
29. The method of claim 28 , wherein the number of cells in the first cell population relative to the number of cells in the second cell population is predetermined.
30. The method of claim 29 , wherein a ratio between cells of the first cell population and cells of the second cell population in the substantially homogeneous cell mixture is from 1:10 9 to 10 9 :1.
31. The method of claim 29 , wherein a ratio between cells of the first cell population and cells of the second cell population in the substantially homogeneous cell mixture is from 1:20 to 20:1.
32. The method of claim 28 , further comprising the step of cutting the matrix with the cells into sections.
33. The method of claim 32 , wherein the matrix is cut into sections having a thickness of up to about 100 μm.
34. The method of claim 32 , wherein the matrix is cut into sections between 50 nm and 100 μm.
35. The method of claim 32 , wherein the matrix is cut into sections between 80 and 120 nm.
36. The method of claim 32 , wherein the matrix is cut into sections between 2 and 5 μm.