Blood replacement with nanobiotechnologically engineered hemoglobin and hemoglobin nanocapsules

Abstract

Unlike donor red blood cells (RBCs), blood substitutes can be treated to remove infective agents and can be used on the spot or in the ambulance in emergency without the time-consuming typing and cross-matching. Donor RBC requires storage at 4 degrees and is only good for 42 days, but blood substitutes can be stored for much longer time. For example, a bovine polyhemoglobin (PolyHb) can be stored at room temperature for more than 1 year. It has been shown as far back as 1957 that artificial RBC can be prepared with ultrathin polymer membranes of nanodimension thickness. To increase the circulation time, the first-generation engineered hemoglobin (Hb) is formed by using glutaraldehyde to crosslink Hb into soluble nanodimension PolyHb that has been tested clinically in patients. Further extension includes conjugated Hb, intramolecularly crosslinked Hb and recombinant Hb. For certain clinical uses, in addition to engineered Hb, we also need antioxidants to remove oxygen radicals to prevent injury from ischemia reperfusion. Thus, we use nanobiotechnology to prepare second-generation engineered Hb by assembling Hb together with superoxide dismutase (SOD) and catalase (CAT) to form a nanodimension soluble complex of polyhemoglobin (PolyHb)-CAT-SOD. A third generation system is to prepare nanodimension complete artificial RBCs that can circulate for sufficient length of time after infusion. One approach uses lipid vesicles to encapsulate hemoglobin (Hb). Another approach is to use biodegradable polymer-like polylactic acid or a copolymer of polyethylene glycol-polylactide (PEG-PLA) to form the membrane of nanodimension complete artificial RBC (www.artcell.mcgill.ca).

FIGURE 1

(a) Artificial red blood cell (RBC) with nanodimension thickness nylon-protein membrane. Spherical in hypotonic solution, becoming ‘crenated’ in hypertonic solutions. Reversible when moved from one solution to another. (b) An example of assembling of biological molecules to form polyhemoglobin (PolyHb) and conjugated hemoglobin (Hb) in the form of nanodimension thickness membrane for artificial cells (left) or as soluble nanodimension complexes of PolyHb or conjugated Hb (Reprinted with permission from Ref . Copyright 2007 Taylor & Francis).

FIGURE 2

(a) Upper: Four types of engineered hemoglobin (Hb): (1) Polyhemoglobin (PolyHb) based on nanobiotechnology, (2) conjugated Hb, (3) intramolecularly crosslinked Hb, and (4) recombinant Hb. (b) Lower right: Larger complexes, like PolyHb and conjugated Hb cannot cross the intercellular junctions of the endothelial lining of vascular wall. Lower left: Small single Hb molecules, such as intramolecularly crosslinked Hb and recombinant Hb, can cross and bind and remove the nitric oxide needed for maintaining the normal tone of smooth muscles. This results in the constriction of blood vessels (Reprinted with permission from Ref . Copyright 2007 Taylor & Francis).

FIGURE 3

(Upper left) Polyhemoglobin (PolyHb) formed by nanobiotechnological assembling of hemoglobin (Hb) molecules into soluble nanodimension complex. (Upper right) Soluble PolyHb-catalase (CAT) containing Hb and CAT. (Lower left) Soluble PolyHb-CAT-superoxide dismutase (SOD) containing Hb, CAT, and SOD. (Lower right) PolyHb-tyrosinase as oxygen carrier that also remove tyrosine to inhibit the growth of melanoma (Reprinted with permission from Ref . Copyright 2007 Taylor & Francis).

FIGURE 4

Effect of superoxide on the stability of: (Upper) PolyHb; (Lower left) crosslinked hemoglobin (Hb) and enzymes obtained directly from red blood cell (RBC) hemolysate; (Lower right) crosslinked Hb and enzymes obtained directly from RBC hemolysate but with more enzymes extracted from RBCs added. (Reprinted with permission from Ref . Copyright 2009 Taylor & Francis).

FIGURE 5

(Top) Amount of membrane material in lipid-encapsulated Hb (LEH) and polylactic acid (PLA) nano-red blood cell (RBC); (middle) fate of polylactide membrane in PLA nano-RBC compared with PLA metabolism; (bottom) hemoglobin (Hb) concentration reported (Reprinted with permission from Ref . Copyright 2007 Taylor & Francis).

FIGURE 6

(a and b) Biodegradable polymeric membrane nanoartificial red blood cell (RBC) with diameters of 80–100 nm containing hemoglobin (Hb) and RBC enzymes (Reprinted with permission from Ref . Copyright 2007 Taylor & Francis).

FIGURE 7

Histology of liver in rats toploaded with nanoartificial red blood cell (RBC) (a), LactRing (b), SF-Hb (c), polyhemoglobin (PolyHb) (d), or RBC (e). Under light microscope, there was no abnormality in Groups a, b, d, and e. For Group c infused with SF-Hb, there is hemoglobin (Hb) accumulation and steatmotosis. H&E staining, × 400 (Reprinted with permission from Ref . Copyright 2008 Taylor & Francis).