Methods for enhancing yield of stem cell cultures and enhancing stem cell therapy

Abstract

The present application relates to methods and compositions for the generation of therapeutic cells having reduced incidence of karyotypic abnormalities. In several embodiments cardiac stem cells are cultured in an antioxidant-supplemented media that reduces levels of reactive oxygen species, but does not down regulate DNA repair mechanisms. In several embodiments, physiological oxygen concentrations are used during culture in order to increase the proliferation of stem cells, decrease the senescence of the cells, decrease genomic instability, and/or augment the functionality of such cells for cellular therapies.

1 . A method of increasing the yield of cardiac stem cells in culture, comprising:
 obtaining a population of cardiac stem cells isolated from a source of cardiac tissue;   restricting oxygen concentrations in a culture environment to physiologic oxygen concentrations,   wherein said physiologic oxygen concentrations are between about 4% and 7%;   culturing said cardiac stem cells in said restricted oxygen culture environment;   wherein said physiologic levels of oxygen increase the rate at which the cardiac stem cells proliferate, thereby increasing the yield of cardiac stem cells as compared to culture conditions that employ non-physiologic levels of oxygen,   wherein the yield of cardiac stem cells is increased per unit weight of said source of cardiac tissue as compared to the yield of cardiac stem cells cultured in conditions that employ non-physiologic concentrations of oxygen, and   wherein the per unit weight yield is increased by at least about 5% for a given time period of culturing.   
     
     
         2 . The method of  claim 1 , wherein the per unit weight yield is increased by at least about 20% for a given time period of culturing. 
     
     
         3 . The method of  claim 1 , wherein the increased yield reduces the amount the amount of time that the cardiac stem cells are cultured in order to reach a certain population as compared to the amount of time cardiac stem cells are cultured in non-physiologic concentrations of oxygen in order to reach said certain population. 
     
     
         4 . The method of  claim 3 , wherein the increased yield reduces the amount the amount of time required for culturing by 20%. 
     
     
         5 . The method of  claim 3 , wherein the increased yield reduces the amount the amount of time required for culturing by 50%. 
     
     
         6 . The method of  claim 1 , wherein said culturing in physiologic oxygen concentrations reduces the incidence of karyotypic abnormalities in the cultured cardiac stem cells as compared to cardiac stem cells cultured in non-physiologic concentrations of oxygen. 
     
     
         7 . The method of  claim 6 , wherein said culturing in physiologic oxygen concentrations reduces the incidence of aneuploidy in the cultured cardiac stem cells as compared to cardiac stem cells cultured in non-physiologic concentrations of oxygen. 
     
     
         8 . The method of  claim 1 , wherein the cardiac stem cells comprise cardiospheres, cardiosphere derived cells, or a subsequent generation of cardiospheres. 
     
     
         9 . The method of  claim 1 , wherein the cardiac stem cells are suitable for administration of a subject having damaged or diseased cardiac tissue. 
     
     
         10 . The method of  claim 9 , wherein the tissue from which the cultured cardiac stem cells were isolated is allogeneic with respect to said subject. 
     
     
         11 . The method of  claim 9 , wherein the tissue from which the cultured cardiac stem cells were isolated is autologous with respect to said subject. 
     
     
         12 . The method of  claim 9 , wherein administration of said cultured cardiac stem cells results in increased engraftment into the cardiac tissue of said subject as compared to engraftment of cardiac stem cells cultured in non-physiologic concentrations of oxygen. 
     
     
         13 . The method of  claim 9 , wherein administration of said cultured cardiac stem cells results in one or more of increased myocardial viability, increased wall thickness, and lower left ventricular volume in the cardiac tissue of said subject as compared to that resulting from administration of cardiac stem cells cultured in non-physiologic concentrations of oxygen. 
     
     
         14 . The method of  claim 1 , further comprising administering at least a portion of said said population of cardiac stem cells to a subject in need of cardiac stem cell therapy due to damaged or diseased cardiac tissue,
 wherein said administered cardiac stem cells engraft into the cardiac tissue of said subject to a greater degree than cardiac stem cells expanded in non-physiologic concentrations of oxygen,   wherein said administered cardiac stem cells survive in the cardiac tissue of said subject to a greater degree than cardiac stem cells expanded in non-physiologic concentrations of oxygen, and   wherein said greater degree of engraftment and survival lead to a greater increase in the cardiac function of said subject as compared to the increase associated with administration of cardiac stem cells expanded in non-physiologic concentrations of oxygen.   
     
     
         15 . The method of  claim 14 , wherein said population of cardiac stem cells is allogeneic with respect to said subject. 
     
     
         16 . The method of  claim 14 , wherein said cardiac stem cells are cardiosphere-derived cells (CDCs). 
     
     
         17 . The method of  claim 14 , wherein said cardiac function is left ventricular ejection fraction and is increased by at least 5% as compared to increased cardiac function due to administration of cardiac stem cells expanded in non-physiologic concentrations of oxygen. 
     
     
         18 . A method of increasing the yield of cardiac stem cells in culture, comprising:
 obtaining a population of cardiac stem cells isolated from a source of cardiac tissue;   restricting oxygen concentrations in a culture environment to physiologic oxygen concentrations,   wherein said physiologic oxygen concentrations are between about 1% and 8%;   culturing said cardiac stem cells in said restricted oxygen culture environment;   wherein said physiologic levels of oxygen increase the rate at which the cardiac stem cells proliferate, thereby increasing the yield of cardiac stem cells as compared to culture conditions that employ non-physiologic levels of oxygen.   
     
     
         19 . The method of  claim 18 , wherein the increased yield reduces the amount the amount of time required for culturing by 20%. 
     
     
         20 . The method of  claim 18 , wherein said culturing in physiologic oxygen concentrations reduces the incidence of aneuploidy in the cultured cardiac stem cells as compared to cardiac stem cells cultured in non-physiologic concentrations of oxygen.