Liposomal-Encapsulated Stroma-Free Hemoglobin as a Potential Blood Substitute.
Annual progress rept. May 80-Apr 81,
CALIFORNIA UNIV SAN FRANCISCO
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A new emulsion encapsulation procedure was developed that dramatically increased efficiency of stroma-free hemoglobin SFH encapsulation yielding hemoglobin containing liposomes HCL ranging in size from 0.05 to 1.0 microns in diameter. There was little or no binding of SFH to these HCL and O2 binding properties were essentialy the same as for solution of SFH. These HCL were less sensitive to osmotic shock than are RBCs and were stable for up to 72 hrs. at 4 C. Mild 3-6 sucrose gradients separated hemoglobin rich from hemoglobin poor HCL. In vivo studies indicated RES uptake was not the primary mechanism for blood clearance, rather extra-cellular binding and erosion are major processes which are saturable indicating that tissue uptake of transfusion should be a small fraction of the total. During this second year we have overcome a major obstacle to further progress scaling-up the emulsion encapsulation procedure to prepare large batches of HCL. The improved large scale procedure, which has advantages over the old micro-scale procedures, allows co-encapsulation of 2,4-dpg with 12 SFH, and procedures HCL with P50 values of 17-20. Further improvement may be possible. Results of a series of in vivo studies have been evaluated relative to the number, diameter and surface area of various liposome doses same composition.
- Medicine and Medical Research