PREPARATION OF FETAL NUCLEATED RED BLOOD CELLS (NRBCs) FOR DIAGNOSTIC TESTING

Abstract

The disclosure relates to methods of preparation of fetal nucleated red blood cells (NRBCs) from biological samples for diagnostic testing.

1 . A method of enriching for fetal nucleated red blood cells (fNRBCs) from a biological sample, comprising:
 (a) subjecting the biological sample to density separation to obtain a fNRBC-containing cell fraction;   (b) subjecting the fNRBC-containing cell fraction obtained in step (a) to magnetic activated cell sorting (MACS) using at least one fNRBC positive selection reagent to obtain a MACS-sorted cell population;   (c) fluorescently labeling cells in the MACS-sorted cell population obtained in step (b) with at least one fNRBC positive selection reagent to obtain a fluorescently labeled cell population; and   (d) sorting the fluorescently labeled cell population obtained in step (c) by flow cytometry to select for fNRBCs, thereby obtaining a population of cells enriched for fNRBCs.   
     
     
         2 . The method of  claim 1 , wherein step (b) utilizes at least one fNRBC positive selection reagent and step (c) utilizes at least two or at least three fNRBC positive selection reagents. 
     
     
         3 . (canceled) 
     
     
         4 . The method of  claim 1 , wherein at least one fNRBC positive selection reagent of step (b) comprises monoclonal antibody 4B9 an anti-CD235a antibody, or a nuclear stain. 
     
     
         5 - 8 . (canceled) 
     
     
         9 . The method of  claim 1 , which further comprises micromanipulation to isolate individual fNRBCs or groups of fNRBCs. 
     
     
         10 . The method of  claim 1 , which does not comprise a negative selection step. 
     
     
         11 . The method of  claim 1 , wherein the fNRBC-containing cell fraction obtained in step (a) is subject to negative selection prior to step (b). 
     
     
         12 . The method of  claim 1 , wherein the MACS-sorted cell population obtained in step (b) is subject to negative selection prior to step (c). 
     
     
         13 . The method of  claim 11 , wherein the negative selection is negative immunoselection. 
     
     
         14 . The method of  claim 13 , wherein the negative immunoselection utilizes one or more antibodies against one or more cell surface markers selected from:
 (a) a T-lymphocyte cell surface marker, optionally CD3, CD4 or CD8;   (b) a B-lymphocyte cell surface marker, optionally CD19, CD20 or CD32;   (c) a pan lymphocyte marker, optionally CD45;   (d) an NK cell surface marker, optionally CD56;   (e) a dendritic cell surface marker, optionally CD11c or CD23; and   (f) a macrophage or monocyte cell surface marker, optionally CD14 or CD33.   
     
     
         15 . A method of enriching for fNRBCs from a biological sample, comprising:
 (a) subjecting the biological sample to density separation to obtain a fNRBC-containing cell fraction;   (b) subjecting the fNRBC-containing cell fraction obtained in step (a) to MACS using at least two fNRBC positive selection reagents to obtain a MACS-sorted cell population;   (c) performing micromanipulation on the MACS-sorted cell population obtained in step (b) to isolate individual fNRBCs or groups of fNRBCs.   
     
     
         16 . The method of  claim 15 , wherein at least one fNRBC positive selection reagent of step (b) comprises monoclonal antibody 4B9 or an anti-CD235a antibody. 
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 15 , which does not comprise a negative selection step. 
     
     
         19 . The method of  claim 15 , wherein the fNRBC-containing cell fraction obtained in step (a) is subject to negative selection prior to step (b). 
     
     
         20 . The method of  claim 15 , wherein the MACS-sorted cell population obtained in step (b) is subject to negative selection prior to step (c). 
     
     
         21 . The method of  claim 19 , wherein the negative selection is negative immunoselection. 
     
     
         22 . The method of  claim 21 , wherein the negative immunoselection utilizes one or more antibodies against one or more cell surface markers selected from:
 (a) a T-lymphocyte cell surface marker, optionally CD3, CD4 or CD8;   (b) a B-lymphocyte cell surface marker, optionally CD19, CD20 or CD32;   (c) a pan lymphocyte marker, optionally CD45;   (d) an NK cell surface marker, optionally CD56;   (e) a dendritic cell surface marker, optionally CD11c or CD23; and   (f) a macrophage or monocyte cell surface marker, optionally CD14 or CD33.   
     
     
         23 . The method of  claim 1 , wherein the biological sample is maternal blood. 
     
     
         24 . The method of  claim 23 , wherein the maternal blood is drawn between about four weeks and about thirty eight weeks of gestation or between about six weeks and about twenty weeks of gestation. 
     
     
         25 . (canceled) 
     
     
         26 . The method of  claim 1 , which further comprises validating the identity of at least one fNRBC as a fetal cell. 
     
     
         27 . A cell population enriched in fNRBCs obtained or obtainable by the method of  claim 1 . 
     
     
         28 . A FACS-sorted cell population containing (a) at least 2, at least 5 or at least 10 and/or (b) up to 15, up to 25, or up to 35 fNRBCs enriched from maternal blood. 
     
     
         29 . The FACS-sorted cell population of  claim 28 , which contains (a) at least 20, at least 50 or at least 100 and/or (b) up to 150, up to 250, or up to 350 FACS events. 
     
     
         30 . The cell population of  claim 27  which is not fixed. 
     
     
         31 . A method of detecting a fetal abnormality, comprising analyzing at least one fNRBC from the cell population of  claim 27  for a fetal abnormality. 
     
     
         32 . The method of  claim 31 , which further comprises enriching for fNRBCs according to the method of any one of  claims 1  to  25  prior to said analyzing. 
     
     
         33 . The method of  claim 31 , which comprises analyzing a single fNRBC for the fetal abnormality. 
     
     
         34 . The method of  claim 31 , which comprises analyzing a group of fNRBCs for the fetal abnormality. 
     
     
         35 . The method of  claim 33  which comprises performing whole genome amplification prior to said analyzing. 
     
     
         36 . The method of  claim 33 , which comprises amplifying a subset of the genome prior to said analyzing. 
     
     
         37 . The method of  claim 31 , wherein the analysis comprises quantitative PCR or is performed on a microarray. 
     
     
         38 . (canceled) 
     
     
         39 . The method of  claim 31 , which further comprises validating the fNRBC or fNRBCs as fetal cells. 
     
     
         40 . The method of  claim 39 , wherein validation comprises performing short tandem repeat (STR) analysis, genetic fingerprinting or single nucleotide polymorphism (SNP) analysis. 
     
     
         41 . The method of  claim 39 , wherein validation comprises comparing fNRBC DNA to maternal DNA and, optionally, to paternal DNA. 
     
     
         42 . (canceled)