Stem Cells Suitable for Transplantation, their Preparation and Pharmaceutical Compositions Comprising Them

Abstract

The present invention relates to stem cells suitable for transplantation and to methods for their preparation.

1 . A method for preparing a population of cells comprising stem cells with a high amount of immature primitive progenitors, the method comprising collecting stem cells and introducing into the cells a DNA fragment comprising the sequence of CXCR4. 
   
   
       2 . A method according to  claim 1 , wherein the population of cells exhibits improved CXCR4 signaling in response to low concentration of SDF-1. 
   
   
       3 . A method according to  claim 1 , wherein the population of cells exhibits improved CXCR4 signaling in response to high concentration of SDF-1. 
   
   
       4 . The method according to  claim 1 , wherein the stem cells are hematopoietic stem cells. 
   
   
       5 . The method according to  claim 4 , wherein the hematopoietic stem cells are CD34 +  enriched. 
   
   
       6 . The method according to  claim 1 , wherein the immature primitive progenitors are of the CD34 + /CD38  −/low  lineage. 
   
   
       7 . The method according to  claim 1 , wherein collecting the stem cells is effected after inducing stem cell mobilization procedure; and/or comprises a surgical procedure. 
   
   
       8 . The method according to  claim 1 , further comprising isolating by FACS stem cells having CXCR4 levels above a predetermined threshold. 
   
   
       9 . The method according to  claim 1 , wherein the stem cells are capable of differentiating towards the myeloid and erythroid lineages. 
   
   
       10 . The method according to  claim 6 , wherein the amount of immature primitive progenitors of the CD34 + /CD38  −/low  lineage are about 1-5% of the population. 
   
   
       11 . The method according to  claim 6 , wherein the immature primitive progenitors of the CD34 + /CD38  −/low  lineage are in an amount equal to or higher than about 3% of the population. 
   
   
       12 . The method according to  claim 2 , wherein the low concentration of SDF-1 is equal to or lower than about 50 ng/ml. 
   
   
       13 . The method according to  claims 2  or  12 , wherein improved signaling is manifested as the enhancement of cell migration mediated by low concentrations of SDF-1. 
   
   
       14 . The method according to  claims 2  or  12 , wherein improved signaling is manifested as the enhancement of cell proliferation mediated by low concentrations of SDF-1. 
   
   
       15 . The method according to  claim 3 , wherein the high concentration of SDF-1 is equal to or higher than about 1 microgram/ml. 
   
   
       16 . The method according to  claims 3  or  15 , wherein improved signaling signaling is manifested by a reduction in desensitization by SDF-1. 
   
   
       17 . A population comprising stem cells expressing a high amount of immature primitive progenitors, exhibiting improved CXCR4 signaling capability in response to low and/or high concentrations of SDF-1, prepared by introducing into the stem cells a DNA fragment comprising the sequence of CXCR4. 
   
   
       18 . The population of stem cells according to  claim 17 , wherein the stem cells are hematopoietic stem cells. 
   
   
       19 . The population of cells according to  claim 17  or  18 , being capable of differentiating towards the myeloid and erythroid lineages. 
   
   
       20 . The population of cells according to  claim 19 , wherein the hematopoietic stem cells are CD34 +  hematopoietic stem cells. 
   
   
       21 . The population of cells according to  claim 17 , wherein the immature primitive progenitors are of the CD34 + /CD38  −/low  lineage. 
   
   
       22 . The population of cells according to  claim 21 , wherein high amount of CD34 + /CD38  −/low  is about 1-5% of the population. 
   
   
       23 . The population of cells according to  claim 21 , wherein the high amount of CD34 + /CD 38−/low  is about and above 3% of the population. 
   
   
       24 . The population of cells according to  claim 17 , wherein the low concentration of SDF-1 is about and below 50 ng/ml. 
   
   
       25 . The population of cells according to  claim 17 , wherein the high concentration of SDF-1 is equal to or higher than about 1 microgram/ml. 
   
   
       26 . A method for increasing homing of stem cells to a target tissue in a subject in need thereof, comprising administering to said subject a population of cells comprising stem cells expressing a high amount of immature primitive progenitors, exhibiting improved CXCR4 signaling capability in response to low and/or high concentrations of SDF-1, prepared by introducing into the stem cells a DNA fragment comprising the sequence of CXCR4. 
   
   
       27 . A method for increasing repopulation of a target tissue in a subject in need thereof, comprising administering to said subject a population of cells comprising stem cells expressing a high amount of immature primitive progenitors, exhibiting improved CXCR4 signaling capability in response to low and/or high concentrations of SDF-1, prepared by introducing into the stem cells a DNA fragment comprising the sequence of-CXCR4. 
   
   
       28 . The method according to  claims 26  or  27 , wherein said target tissue is selected from the group consisting of bone marrow, blood vessel, heart, lung, liver, pancreas, kidney, nervous system, skin, bone and skeletal muscle. 
   
   
       29 . The method according to  claims 26  or  27 , to facilitate transplantation. 
   
   
       30 . The method according to  claim 29 , wherein transplantation follows chemotherapy protocols. 
   
   
       31 . The use method according to  claim 29 , wherein transplantation is autologous. 
   
   
       32 . The method according to  claim 31 , wherein the transplantation involves mobilization of autologous cells. 
   
   
       33 . The method according to  claim 29 , wherein transplantation is heterologous. 
   
   
       34 . The method according to  claim 29 , wherein the transplantation is carried with mobilized stem cells. 
   
   
       35 . A method of treating a disorder in a subject requiring cell or tissue replacement, the method comprising providing to a subject in need thereof a therapeutically effective amount of a population of cells according to anyone of  claims 17  to  25 . 
   
   
       36 . A method of preparing a population of cells comprising stem cells exhibiting CXCR4 with intact 6H8 epitope, the method comprising collecting stem cells and introducing to the cells a DNA fragment comprising the sequence of CXCR4. 
   
   
       37 . A population of cells comprising stem cells comprising intact CXCR4 6H8 epitope prepared by introducing a DNA fragment comprising the sequence of CXCR4. 
   
   
       38 . A method for for transplantation in a subject in need thereof, comprising contacting said subject with the population of cells of  claim 37 . 
   
   
       39 . A method of treating a disorder requiring cell or tissue replacement, the method comprising providing to a subject in need thereof a therapeutically effective amount of a population of cells according to  claim 37 . 
   
   
       40 . A pharmaceutical composition comprising a population of stem cells comprising stem cells exhibiting intact CXCR4 6H8 epitope prepared by introducing to the cells a DNA fragment comprising the sequence of CXCR4.