Lectin-derived progenitor cell preservation factors and methods of use

Abstract

The invention relates to an isolated nucleic acid molecule that encodes a protein that is effective to preserve progenitor cells, such as hematopoietic progenitor cells. The nucleic acid comprises a sequence defined by SEQ ID NO:1, a homolog thereof, or a fragment thereof. The encoded protein has an amino acid sequence that comprises a sequence defined by SEQ ID NO:2, a homolog thereof or a fragment thereof that contains an amino acid sequence TNNVLQVT. Methods of using the encoded protein for preserving progenitor cells in vitro, ex vivo, and in vivo are also described. The invention, therefore, include methods such as myeloablation therapies for cancer treatment wherein myeloid reconstitution is facilitated by means of the specified protein. Other therapeutic utilities are also enabled through the invention, for example, expanding progenitor cell populations ex vivo to increase chances of engraftation, improving conditions for transporting and storing progenitor cells, and facilitating gene therapy to treat and cure a broad range of life-threatening hematologic diseases.

1 - 42 . (Canceled)  
     
     
         43 . A method for preserving progenitor cells, comprising contacting progenitor cells with a protein that: 
 (a) is capable of binding to a flk2/flt3 receptor; and    (b) has at least 95% amino acid sequence identity to an amino acid sequence comprising SEQ ID NO: 2.    
     
     
         44 . A method for preserving progenitor cells, comprising contacting progenitor cells with a protein that: 
 (a) is capable of binding to a flk2/flt3 receptor; and    (b) is encoded by a first nucleic acid molecule that hybridizes under stringent conditions to a second nucleic acid molecule having a nucleotide sequence complementary to a nucleotide sequence comprising SEQ ID NO: 1.    
     
     
         45 . The method of  claim 43  or  44 , wherein the protein is capable of preserving progenitor cells.  
     
     
         46 . The method of  claim 43  or  44 , wherein the protein is capable of inhibiting differentiation of progenitor cells.  
     
     
         47 . The method of  claim 46 , wherein the protein is capable of maintaining progenitor cells in a quiescent or G 0  state of the cell cycle.  
     
     
         48 . The method of  claim 43  or  44 , wherein the protein is capable of preserving progenitor cells in liquid culture.  
     
     
         49 . The method of  claim 43  or  44 , wherein the protein is capable of stimulating proliferation of NIH3T3 fibroblasts expressing the flk2/flt3 receptor in an IL1-dependent manner.  
     
     
         50 . The method of  claim 43  or  44 , wherein the protein is a heterodimer.  
     
     
         51 . The method of  claim 43  or  44 , wherein the protein is derived from a member of the tribe Phaseoleae.  
     
     
         52 . The method of  claim 51 , wherein the protein is derived from  Dolichos lablab, Phaseolus vulgaris  or  Vigna sinensis.    
     
     
         53 . The method of  claim 43  or  44 , wherein the protein is produced recombinantly.  
     
     
         54 . The method of  claim 43  or  44 , wherein the protein is a fusion protein.  
     
     
         55 . The method of  claim 43  or  44 , wherein the progenitor cells comprise hematopoietic progenitor cells.  
     
     
         56 . The method of  claim 43  or  44 , wherein the progenitor cells comprise human cells that express the CD34 antigen and/or the flk2/flt3 receptor.  
     
     
         57 . The method of  claim 43  or  44 , wherein the progenitor cells comprise murine cells that express the Sca antigen but that do not express mature blood cell lineage antigens.  
     
     
         58 . The method of  claim 43  or  44 , wherein the progenitor cells include primitive progenitor cells.  
     
     
         59 . The method of  claim 43  or  44 , wherein the progenitor cells include mature progenitor cells.  
     
     
         60 . The method of  claim 43  or  44 , wherein the progenitor cells are substantially free of stromal cells.  
     
     
         61 . The method of  claim 43  or  44 , wherein the progenitor cells are contacted with the protein ex vivo.  
     
     
         62 . The method of  claim 43  or  44 , wherein the progenitor cells are contacted with the protein in vivo.  
     
     
         63 . The method of  claim 43  or  44 , further comprising contacting the progenitor cells with flk2/flt3 ligand in an amount sufficient to selectively expand the number of progenitor cells without inducing differentiation thereof.  
     
     
         64 . A method for preserving progenitor cells in a mammal, comprising: 
 a) administering to the mammal a protein of  claim 43  or  44  that is capable of preserving progenitor cells, in an amount sufficient to preserve progenitor cells of the mammal in a substantially non-proliferative state;    b) exposing the mammal to myeloablative conditions sufficient to effect ablation of proliferating myeloid cells but not kill non-proliferating progenitor cells; and    c) causing proliferation or differentiation of the preserved progenitor cells.    
     
     
         65 . The method of  claim 64 , wherein the myeloablation conditions comprise bone marrow irradiation, whole body irradiation, or chemically-induced myeloablation.  
     
     
         66 . The method of  claim 64 , wherein step (c) comprises administering to the mammal a cytokine in an amount sufficient to improve the viability of the progenitor cells  
     
     
         67 . The method of  claim 66 , wherein the cytokine is IL-1, IL-3, IL-6, IL-11, KL, or a combination thereof.  
     
     
         68 . The method of  claim 64 , wherein step (c) comprises administering to the mammal a proliferation-stimulating amount of the flk2/flt3 ligand.