Compositions and methods for modifying cell surface glycans

Abstract

Methods and compositions for modifying glycans (e.g., glycans expressed on the surface of live cells or cell particles) are provided herein.

1 - 47 . (canceled) 
     
     
         48 . A composition for modifying a glycan on the surface of viable cells comprising:
 a purified glycosyltransferase polypeptide in a physiologically acceptable solution, wherein the glycosyltransferase has unit activity capable of transferring at least 1.0 μmole of sugar per minute at pH 6.5 at 37° C., to an acceptor glycan;   wherein the purified glycosyltransferase polypeptide and the physiologically acceptable solution is effective to maintain cell viability of at least 70% after 24 hours of contact with the viable cells;   wherein the glycosyltransferase is a fucosyltransferase, galactosyltransferase, sialyltransferase, N-acetylglucosaminyltransferase, or any combination thereof   
     
     
         49 . The composition of  claim 48 , wherein the physiologically acceptable solution is buffered. 
     
     
         50 . The composition of  claim 48 , wherein the physiologically acceptable solution is free of glycerol. 
     
     
         51 . The composition of  claim 48 , further comprising an appropriate sugar donor. 
     
     
         52 . The composition of  claim 51 , wherein the sugar donor is fucose, GDP-fucose, galactose, UDP-galactose, sialic acid, CMP-sialic acid, N-acetylglucosamine, UDP-N-acetylglucosamine, or any combination thereof 
     
     
         53 . The composition of  claim 48 , wherein the viable cells are differentiated cells or stem cells. 
     
     
         54 . The composition of  claim 53 , wherein the stem cells are hematopoetic stem cells, mesenchymal stem cells, tissue stem/progenitor cells, umbilical cord stem cells, or embryonic stem cells. 
     
     
         55 . The composition of  claim 48 , wherein the viable cells express CD44. 
     
     
         56 . An ex vivo method for modifying a glycan on the surface of a viable cell, the method comprising:
 contacting a population of cells with a sugar donor and an exogenous glycosyltransferase, wherein the contacting occurs in a physiologically acceptable solution wherein the glycosyltransferase has unit activity capable of transferring at least 1.0 μmole of sugar per minute at pH 6.5 at 37° C., to an acceptor glycan;   wherein the sugar donor, the exogenous glycosyltransferase, and the physiologically acceptable solution are effective to maintain cell viability of at least 70% after 24 hours of contact with the viable cell; and   wherein the glycosyltransferase is a fucosyltransferase, galactosyltransferase, sialyltransferase, N-acetylglucosaminyltransferase, or any combination thereof   
     
     
         57 . The method of  claim 56 , wherein the physiologically acceptable solution is buffered. 
     
     
         58 . The method of  claim 56 , wherein the physiologically acceptable solution is free of glycerol. 
     
     
         59 . The method of  claim 56 , further comprising an appropriate sugar donor. 
     
     
         60 . The method of  claim 59 , wherein the sugar donor is fucose, GDP-fucose, galactose, UDP-galactose, sialic acid, CMP-sialic acid, N-acetylglucosamine, UDP-N-acetylglucosamine, or any combination thereof. 
     
     
         61 . The method of  claim 56 , wherein the viable cell is a differentiated cell or stem cell. 
     
     
         62 . The method of  claim 61 , wherein the stem cells are hematopoetic stem cells, mesenchymal stem cells, tissue stem/progenitor cells, umbilical cord stem cells, or embryonic stem cells. 
     
     
         63 . The method of  claim 56 , wherein the viable cell expresses CD44. 
     
     
         64 . A kit for modifying a glycan on the surface of a cell, the kit comprising:
 a purified glycosyltransferase polypeptide in a physiologically acceptable solution, wherein the glycosyltransferase has unit activity capable of transferring at least 1.0 μmole of sugar per minute at pH 6.5 at 37° C., to an acceptor glycan;   wherein the purified glycosyltransferase polypeptide and the physiologically acceptable solution is effective to maintain cell viability of at least 70% after 24 hours of contact with the viable cells;   wherein the glycosyltransferase is a fucosyltransferase, galactosyltransferase, sialyltransferase, N-acetylglucosaminyltransferase, or any combination thereof; and   instructions for their use.   
     
     
         65 . The kit of  claim 64 , wherein the physiologically acceptable solution is buffered. 
     
     
         66 . The kit of  claim 64 , wherein the physiologically acceptable solution is free of glycerol. 
     
     
         67 . The kit of  claim 64 , further comprising an appropriate sugar donor.