A new instrument to characterize O2 transport by cell-free hemoglobin and/or mixtures of cell-free hemoglobin and red blood cells has been invented, and a patent has been applied for. This instrument measures diffusional O2 transport using a small sample, and is applicable both to the development of cell-free hemoglobin solutions and to monitoring patients who have received them. The goal of this proposal is to optimize the design of this instrument to measure O2 transport by cell-free hemoglobin solutions in vitro using an artificial capillary system. Under Specific Aim 1, we will build an artificial capillary system to assess O2 transport by cell- free hemoglobin solutions in vitro. We will optimize the breadboard design of our present artificial capillary instrument. Measurements of O2 transport will be made using cell-free hemoglobin solutions, including model solutions of PEG-hemoglobin and cross-linked tetrameric hemoglobin, and RBC suspensions. Under Specific Aim 2, we will automate the capillary apparatus and further develop software for data interpretation. The data- analysis model uses mathematical concepts based on the Krogh cylinder model for O2 transport out a cylindrical tube of defined geometry (i.e., the artificial capillary). This programs requires 1) optimization for run time efficiency and 2) testing against experimental data from hemoglobin solutions and/or red blood cells in the artificial capillary device. The hypothesis underlying this proposal is that a new method to assess O2 transport by cell-free oxygen carriers is required before candidate products can be evaluated accurately. This is due to the phenomenon of facilitated diffusion of O2 in the presence of cell-free carriers, which can lead to autoregulatory vasoconstriction. PROPOSED COMMERCIAL APPLICATIONS: Methods of clinical evaluation of O2 transport (Hb, Het) in the presence of cell-free oxygen carriers are inadequate. We have invented a new instrument to characterize O2 transport by cell-free hemoglobin that includes evaluation of facilitated diffusion. This instrument has great potential for clinical measures in patients who have received hemoglobin- based products, as well as potential in the testing of new candidate solution.
