| The development of HBOCs (Hemoglobin-Based Oxygen Carriers) as blood substitutes has reached an impasse due to clinically adverse outcomes, such as vasoconstriction caused by NO (Nitric Oxide) scavenging, oxidative damage and so on. Currently, the HBOCs can’t substitute for red blood cells completely in clinical blood transfusion, but its function as therapeutic agent can be applied in other clinical indications to carry oxygen. The FDA suggests for the categories of HBOCs indications:local perfusion, uncontrolled hemorrhagic shock, perioperative application. In this doctoral dissertation, a new type of HBOCs-pPolyHb (glutaraldehyde-polymerized porcine hemoglobin) was prepared and two types of clinical indications were chosen to test the effectiveness of pPolyHb as oxygen therapeutic agent.The SBTx (Small bowel transplantation) has became a standard clinical treatment for short bowel syndrome or irreversible intestinal function failure. The optimum preservation of the organ is essential for the success of transplantation. The aim of the present study is to investigate the time-related morphological changes and biochemical indicators of small bowel tissue in preservation solutions. Rat small bowels were preserved in HCA (hypertonic citrate adenine solution), HCA with pPolyHb or University of Wisconsin solution (UW), and light microscopy was used to evaluate the integrity of the small bowel. Small bowels were placed in different preservation solutions at4℃for12,24and36h. In the small intestine preservation experiment, pathology analysis results showed that the short-term (12and24h) preservation effect of pPolyHb+HCA solution approached the level of UW solution, there was no significant difference between these two groups. However, its long-term preservation effect (36h) was significantly better than the UW solution. Both long-term and short-term preservation effects were superior to the HCA solution. The ATP (Adenosine triphosphate) content test showed that the ATP content of pPolyHb+HCA group was significantly higher than the control group (UW group and HCA group). Blood gas analysis results indicated that the pH value of PolyHb+HCA solution maintained normal level all the time; the change of ΔHCO3-(HCO3-value) was significantly higher than the control groups; the content of Lac (Lactate) was significantly lower than the control groups. These results demonstrated that the pPolyHb could notably improve the preservation effects for small intestine, and also prompted to improve the oxygen supply of small intestine tissue as to optimize its preservation in vitro.Hemorrhagic shock is a pathologic state in which intravascular volume and tissue oxygen delivery are impaired, leading to circulatory collapse and cellular ischemia. Resuscitation by the HBOCs is appealing in both restore intravascular volume and tissue oxygenation, without the limitations in the supply and immunomodulatory effects of packed red blood cells. In this study, we established a rat model of uncontrolled hemorrhagic shock resuscitation to verify the effectiveness of pPolyHb. Firstly, we have chosen five gradient concentrations to determine the minimum effective dose of pPolyHb, and then used it as the final concentration of experimental group to compare with other five resuscitation solutions for the effects on changes of hemodynamic values and blood gas results to verify the validity of pPolyHb.Physiological indicators showed that the blood pressure, heart rate, respiratory rate were restored to the base value after resuscitation by2.0g/kg pPolyHb or1.5g/kg pPolyHb with twice saline. The results indicated that the hemodynamics effects of these two groups were better than the lower concentration groups. The blood gas results indicated that the oxygen-carrying capacity of2g/kg pPolyHb group and1.5g/kg pPolyHb group were better than that of low concentration group, and acid-base balance were also slightly better than the lower concentration groups. Meanwhile, the indicators of electrolyte balance and anaerobic metabolism had no significant difference among the five concentration groups. The survival rates of2.0g/kg and1.5g/kg pPolyHb group within72hours were100%, much higher than those of low concentration groups. Therefore,1.5g/kg pPolyHb was chosen as the minimum effective dose. Next, the1.5g/kg pPolyHb was compared with other five resuscitation fluids to verify the effectiveness. The physiological datum showed that the1.5g/kg pPolyHb and autologous blood group had better recovery effect than the other resuscitation fluids. The blood gas results notified that the1.5g/kg pPolyHb and autologous blood group showed a better capacity to carry oxygen and balance acid-base. Many of the blood gas indicators in1.5g/kg pPolyHb were significantly better than the negative control. The electrolyte balance datum were similar among each group, while the anaerobic metabolism index of the pPolyHb group, the AB (Autologous Blood) group and RBC (Red Blood Cell) group had shown obvious superiority.The survival rates of1.5g/kg pPolyHb and AB group were100%, higher than other liquid recovery groups. Rat pathological anatomic analysis results showed that the oxygen-carrying resuscitation liquid (1.5g/kg pPolyHb group, the AB group and RBC group) provided better tissue integrity than other three groups in heart, lung and liver.Conclusion:(1) The pPolyHb could maintain the aerobic respiration of organization and prevent anaerobic metabolism, which could be considered as an effective oxygen therapeutic agent in the small intestine preservation solution in vitro;(2) The pPolyHb, as an oxygen therapeutic agent could resuscitate the hemorrhagic shock rats effectively, which implies its possible clinical application in hemorrhagic shocktherapy.(3) The results of this study provided evidence for new selection of clinical indication for the pPolyHb. |
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