Andre Palmer Laboratory for Artificial Blood Research
RESEARCH
Universal oxygen (O2) carrying solutions that can replace the O2 storage and transport functions of red blood cells (RBCs) will greatly improve clinical outcomes for trauma victims and patients undergoing high-blood-loss surgical procedures. These O2 carriers are to be used when blood is not readily available, such as on the battlefield, during natural disasters, at the site of a terrorist attack or in rural areas without hospital access. My lab employs a simple approach to design hemoglobin-based O2 carriers (HBOCs) as RBC substitutes. Our design strategy is based on the observation that transfusion of cell-free hemoglobin results in vasoconstriction, systemic hypertension and oxidative tissue injury. The root cause of these side-effects stem from the ability of hemoglobin to extravasate through pores lining the wall of blood vessels, and consequently scavenge nitric oxide from the surrounding vasculature as well as catalyze production of reactive oxygen species. Therefore, our design strategy focuses on increasing the molecular diameter of HBOCs so that these molecules are unable to traverse across the wall of blood vessels into the tissue space to limit/prevent these side-effects. Approaches to accomplish this include: polymerizing hemoglobin into molecular aggregates, conjugating poly(ethylene) glycol/oligosaccharides to the surface of the hemoglobin molecule, encapsulating hemoglobin inside the core of submicron vesicles and using naturally occurring hemoglobin superassemblies from annelids. These simple strategies mitigate the adverse side-effects associated with the infusion of cell-free Hb into the circulatory system.
SELECTED PUBLICATIONS
- A. T. Williams, A. Lucas, C. Muller, C. Munoz, C. Bolden-Rush, A. F. Palmer, P. Cabrales, “Resuscitation from hemorrhagic shock with fresh and stored blood and polymerized hemoglobin,” Shock Feb 21. doi: 10.1097/SHK.0000000000001530. (2020)
- C. R. Muller, A. Lucas, V. Courelli, A. T. Williams, F. Dos Santos, C. Cuddington, S. Moses, A. F. Palmer, E. Kistler, P. Cabrales, “Resuscitation from hemorrhagic shock after traumatic brain injury with polymerized hemoglobin,” Scientific Reports Jan 28;11(1):2509. doi: 10.1038/s41598-021-81717-3. (2021)
- C. R. Muller, A. T. Williams, C. Walser, A. M. Eaker, J. L. Sandoval, V. Courelli, C. T. Cuddington, S. Wolfe, A. F. Palmer, P. Cabrales, “Safety and efficacy of human polymerized hemoglobin on guinea pig resuscitation from hemorrhagic shock,” Scientific Reports Nov 28;12(1):20480. doi: 10.1038/s41598-022-23926-y. (2022)
- A. Greenfield, D. R. Lamb, X. Gu, K. Thangaraju, S. Setua, A. Yahya, A. Vahedi, M. A. Khan, Q. Wang, P. W. Buehler, A. F. Palmer, “Biophysical analysis and preclinical pharmacokinetics-pharmacodynamics of tangential flow filtration fractionated polymerized human hemoglobin as a red blood cell substitute,” Biomacromolecules Mar 6. doi: 10.1021/acs.biomac.3c00051. (2023)
O2 transport remains one of the main limiting factors in culturing large dimension tissue engineered constructs. When mammalian cells are placed in aqueous media, their metabolism and thus growth is severely constrained by the availability of O2. Since O2 is not very soluble in water, my research focuses on approaches to better improve O2 storage and transport to cultured cells, especially cells grown in bioreactors. Towards this goal, we have used HBOCs to deliver increased levels of O2 and physiological O2 gradients to hepatocytes and β-cells housed in hollow fiber bioreactors to serve as a bioartificial liver assist device and bioartificial pancreas, respectively. We have also used HBOCs to deliver O2 to transplanted islets to reduce graft hypoxia and improve graft function.
SELECTED PUBLICATIONS
- D. Espes, J. Lau, M. Quach, U. Banerjee, A. F. Palmer, P. O. Carlsson, “Co-transplantation of polymerized hemoglobin reduces beta cell hypoxia and improves beta cell function in intramuscular islet grafts,” Transplantation Oct;99(10):2077-82. doi: 10.1097/TP.0000000000000815. (2015)
- D. A. Belcher, U. Banerjee, C. M. Baehr, K. E. Richardson, P. Cabrales, F. Berthiaume, A. F. Palmer, “Mixtures of tense and relaxed state polymerized human hemoglobin regulate oxygen affinity and tissue construct oxygenation,” PLoS One Oct 11;12(10):e0185988. doi: 10.1371/journal.pone.0185988. (2017)
- L. Diaz-Starokozheva, D. Das, X. Gu, J. T. Moore, L. R. Lemmerman, I. Valerio, H. M. Powell, N. Higuita-Castro, M. R. Go, A. F. Palmer, D. Gallego-Perez, “Early intervention on ischemic tissue with oxygen nanocarriers enables successful implementation of restorative cell therapies,” Cellular and Molecular Bioengineering May 29;13(5):435-446. doi: 10.1007/s12195-020-00621-4. (2020)
- D. A. Belcher, A. Lucas, P. Cabrales, A. F. Palmer, “Tumor vascular status controls oxygen delivery facilitated by infused polymerized hemoglobins with varying oxygen affinity,” PLOS Computational Biology Aug 20;16(8):e1008157. doi: 10.1371/journal.pcbi.1008157. (2020)
Plasma substitutes (PSs), although they lack O2 carrying capacity, are an important class of transfusion solution that can maintain blood volume. They are more advantageous compared to RBC transfusion due to the absence of immunological reactions, longer shelf life, cost-effectiveness and reduced risk of infection. However, conventional PSs are often limited by undesirable side effects, such as RBC aggregation and nephrotoxicity (dextrans), coagulation disturbances (hydroxyethyl starches) and limited intravascular retention (albumin). Notwithstanding this minor limitation, albumin is considered a near optimal PS, whose unique molecular size, shape and electrical charge prevents vascular extravasation into most tissues. Despite its natural prevalence in the bloodstream, human serum albumin (HSA) can increase the risk of mortality when administered to patients with increased vascular permeability (i.e., patients suffering from burns, septic shock, ischemia-reperfusion injury and endothelial dysfunction). This occurs in injured vascular endothelium with increased capillary permeability resulting from physical damage, inflammation, neutrophils or endothelial swelling. Our research proposes re-engineering PSs beyond simple blood volume management, by preserving the interaction between the components of blood and the microcirculation, in order to increase perfusion and maximize oxygenation, thus creating a viable alternative to RBC transfusion or to act as a bridge until RBCs are available. We hypothesize that the deleterious effects of HSA extravasation can be decreased/eliminated by polymerizing HSA (PolyHSA), in order to increase its molecular size, prevent extravasation and increase intravascular retention, while simultaneously decreasing its colloid osmotic pressure and increasing its solution viscosity. Our work on PolyHSA has demonstrated its ability to increase plasma viscosity, which induces mechanotransduction of the endothelium and elicits vasodilation and increased tissue perfusion. We have demonstrated that PolyHSA is able to resuscitate animals from hemorrhagic shock, endotoxemia, sepsis, ischemia reperfusion injury and serve as a machine perfusion perfusate.
SELECTED PUBLICATIONS
- C. Messmer, O. Yalcin, A. F. Palmer, P. Cabrales, “Small volume resuscitation from hemorrhagic shock with polymerized human serum albumin,” The American Journal of Emergency Medicine Oct;30(8):1336-46. doi: 10.1016/j.ajem.2011.09.018. (2012)
- D. A. Belcher, A. T. Williams, A. F. Palmer, P. Cabrales, “Polymerized albumin restores impaired hemodynamics in endotoxemia and polymicrobial sepsis,” Scientific Reports May 25;11(1):10834. doi: 10.1038/s41598-021-90431-z. (2021)
- D. A. Belcher, A. T. Williams, C. Walser, C. R. Muller, C. J. Munoz, A. F. Palmer, P. Cabrales, “Attenuating ischemia and reperfusion injury with polymerized albumin,” Journal of Applied Physiology Dec 16. doi: 10.1152/japplphysiol.00117.2021. (2021)
- E. Eren, S. M. Black, B. F. Reader, E. Beal, C. Cuddington, D. A. Belcher, A. F. Palmer, B. A. Whitson, “Novel polymerized human serum albumin for ex-vivo lung perfusion,” ASAIO Journal Mar 29. doi: 10.1097/MAT.0000000000001918. (2023)
Haptoglobin (Hp), hemopexin (Hpx) and transferrin (Tf) are important acute phase proteins, but also exist at relatively high levels (1-8 mg/ml) in normal plasma. With regard to acute and chronic intravascular and extravascular RBC destruction, these proteins play a critical role in the clearance of Hb, heme and iron and facilitate erythropoiesis through processes of iron recycling to the bone marrow and spleen. My lab has developed a hemopexin mimetic (apohemoglobin, apoHb) that can scavenge heme, and when bound to Hp as the apoHb-Hp complex can scavenge and detoxify both heme and cell-free Hb.
SELECTED PUBLICATIONS
- I. S. Pires, D. A. Belcher, R. Hickey, C. Miller, A. K. Badu-Tawiah, J. H. Baek, P. W. Buehler, A. F. Palmer, “Novel manufacturing method for producing apohemoglobin and its biophysical properties,” Biotechnology and Bioengineering Jan;117(1):125-145. doi: 10.1002/bit.27193. (2020)
- I. S. Pires, A. F. Palmer, “Tangential flow filtration of haptoglobin,” Biotechnology Progress Sep;36(5):e3010. doi: 10.1002/btpr.3010. (2020)
- C. J. Munoz, I. S. Pires, J. H. Baek, P. W. Buehler, A. F. Palmer, P. Cabrales, “A novel apo-hemoglobin-haptoglobin complex attenuates the pathobiology of circulating acellular hemoglobin and heme,” American Journal of Physiology Heart and Circulatory Physiology May 1;318(5):H1296-H1307. doi: 10.1152/ajpheart.00136.2020. (2020)
- D. A. Belcher, C. J. Munoz, I. S. Pires, A. T. Williams, P. Cabrales, A. F. Palmer, “Apohemoglobin-haptoglobin complexes attenuate the hypertensive response to low-molecular-weight polymerized hemoglobin,” Blood Advances Jun 23;4(12):2739-2750. doi: 10.1182/bloodadvances.2020002045. (2020)
