Process for multi-analyses of rare cells extracted or isolated from biological samples through filtration

A process for analyzing DNA molecules in rare cells isolated from blood obtained from a subject, the method comprising:

• a) treating a diluted blood sample with an anticoagulant, selectively only lysing red blood cells in the diluted blood sample that is treated with the anticoagulant, and producing a fixed blood sample by fixing the diluted blood sample that is treated with the anticoagulant and has lysed red blood cells;
• b) filtering the fixed diluted blood sample from step a) by vertical filtration with a negative pressure through a polycarbonate filter, wherein the filter has a pore size from 3 μm to 30 μm, has a pore density from 3×103 pores/cm2 to 5×106 pores/cm2, and is suitable for retention of the rare cells but permits passage of cells smaller than the rare cells, wherein the rare cells are nucleated cells larger than neutrophils and mature lymphocytes, and wherein the filter comprises elementary filtration areas, each of the elementary filtration areas having a surface which equals to the area of a disk with a diameter between 0.6 cm and 3 cm, wherein the surface of each of the elementary filtration areas and the number of elementary filtration areas of the filter are chosen according to the nature of a fluid to be filtered, the nature of biological particles to be separated when the filter is used, and the volume of the fluid to be filtered, and wherein the ratio of a total volume of fluid filtered through the surface of each of the elementary filtration areas of the filter to the area of each of the elementary filtration areas of the filter is less than 40 ml/cm2;
• c) recovering the rare cells on the filter or the rare cells detached from the filter cells;
• and
• e) analyzing the DNA molecules from the recovered rare cells, thereby analyzing the DNA molecules in the rare cells isolated from the blood obtained from the subject.