Separation of fetal cells from maternal blood

Abstract

It is often important for medical purposes to obtain nucleated fetal cells during pregnancy. For example, the procedures of amniocentesis or chrionic villae extraction are carried out for this purpose. But these methods are invasive, and carry a small but positive risk to the patient, and are complicated to perform. On the other hand, the purpose of my invention is to obtain nucleated fetal cells (fetal nucleated reticulocytes) from maternal blood, which eliminates the need for invasive methods. There are a small number of nucleated fetal red blood cells (reticulocytes) in maternal blood and my invention is a method and apparatus for separating these fetal cells from maternal blood. Several methods have previously been proposed, involving fluorescent antibody antigen reactions (immunofluorescence), other antibody-antigen means, that depend on the difference between the cell walls of maternal and fetal blood cells, but all of these methods have been unsatisfactory because they have proved to be unreliable and expensive, and to involve some final additional technique to isolate the cells, such as flow cytometry. On the other hand, my invention does not use antibody-antigen means, but is based on the fundamental difference between maternal and fetal cells, namely that the former contains adult hemoglobin (HbA) while the latter contains fetal hemoglobin (HbF). The difference in the properties of these hemoglobin molecules themselves enables the fetal cells to be separated from the maternal cells by a magnetic field means.