Dextran-hemoglobin conjugates as blood substitutes

Abstract

An hemoglobin (Hb)-Dextran (Dx) conjugate having a molecular weight between 50 kD and 500 kD provides a blood substitute that results in acceptable erythrocyte sedimentation rate (ESR) and excretion rate (EXC) values. DxHb conjugates of the invention can be used for a variety of purposes as an alternative to blood.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . An oxygen carrying compound comprising a conjugate of hemoglobin covalently joined to a polysaccharide, said conjugate having an average molecular weight of from about 50 kD to about 500 kD.  
     
     
         2 . The compound of  claim 1  wherein said compound results in an erythrocyte sedimentation rate (ESR) of less than 20 mm/hr, using Wintrobe's Method, and a renal excretion rate (EXC) of less than 1%.  
     
     
         3 . The compound of  claim 1  wherein the polysaccharide is dextran.  
     
     
         4 . The compound of  claim 3  wherein said conjugate has an average molecular weight of about 89 kD to about 116 kD.  
     
     
         5 . The compound of  claim 2  wherein sa id compound results in an ESR of less than 1 mm/hr, using Wintrobe's Method, and a renal EXC of less than 0.2%.  
     
     
         6 . A method for preparing an oxygen carrying compound, said compound comprising a conjugate of hemoglobin covalently bound to a polysaccharide, said method comprising: 
 1) reacting the polysaccharide with a bromine compound to provide bromine groups on said polysaccharide, thereby providing an activated polysaccharide;    2) filtering said activated polysaccharide with a first filter;    3) reacting said activated polysaccharide with hemoglobin thereby providing a coupled dextran-hemoglobin molecule;    4) filtering said dextran-hemoglobin molecule with a second filter.    
     
     
         7 . The method of  claim 6  wherein said polysaccharide is dextran.  
     
     
         8 . The method of  claim 7  wherein said dextran has an average molecular weight of 20 kD.  
     
     
         9 . The method of  claim 6  wherein said first filter has a pore size that results in a retentate having a molecular weight greater than 500 kD.  
     
     
         10 . The method of  claim 9  wherein said first filter has a pore size that results in a retentate having a molecular weight greater than 300 kD.  
     
     
         11 . The method of  claim 6  wherein said hemoglobin is stroma-free hemoglobin.  
     
     
         12 . The method of  claim 6  wherein said second filter has a pore size that results in a retentate having a molecular weight greater than 500 kD.  
     
     
         13 . The method of  claim 6  further including, after step 4, the step of filtering the dextran-hemoglobin molecule through a third filter.  
     
     
         14 . The method of  claim 13  wherein said third filter has a pore size that results in a filtrate having a molecular weight greater than 80 kD.