title: Genetically engineered pig red blood cells for clinical transfusion: initial in vitro studies.
abstract: BACKGROUND
  Pigs are a potential source of red blood cells (RBCs) and could resolve the shortage of human blood for transfusion. This study investigated in vitro the compatibility of genetically engineered pig RBCs (pRBCs) with the human innate immune response.
  
  
  METHODS
  Human volunteers of all ABO blood types were sources of sera and those of O blood type were sources of circulating monocytes/macrophages. RBCs from ABO-compatible (ABO-C) and ABO-incompatible (ABO-I) humans and wild-type (WT) and alpha-1,3-galactosyltransferase gene-knockout (GTKO) pigs were tested for hemagglutination, immunoglobulin (Ig)M/IgG antibody binding, and complement-dependent cytotoxicity (CDC) using human sera. Phagocytosis of RBCs by human monocyte-derived macrophages was measured by coculture in the absence or presence of pooled human O serum.
  
  
  RESULTS
  RBCs showed significant differences (p < 0.01) with regard to hemagglutination, IgM and IgG binding, and CDC (ABO-C < GTKO < ABO-I < WT). In the absence of pooled human O serum (antibodies), there was no phagocytosis of any RBCs; in the presence of serum (antibodies), phagocytosis of ABO-I RBCs was greater than of WT (p < 0.01), which in turn was greater than of GTKO RBCs (p < 0.05).
  
  
  CONCLUSIONS
  GTKO RBCs were significantly more compatible than ABO-I and WT RBCs, but were not comparable to ABO-C combinations. In the presence of antibody, human monocyte-derived macrophages phagocytosed ABO-I RBC/sera combinations more efficiently than pRBCs. These observations contribute to our ultimate goal of using genetically engineered pRBCs for clinical blood transfusion. However, pigs will require other modifications or manipulations if they are to become suitable for human transfusion.
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Starzl Biomedical Science Tower, W1540, 200 Lothrop Street, Pittsburgh, PA 15261, USA.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Long
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Hara
authors.forename: Zachary
authors.initials: Z
authors.lastname: Pawlikowski
authors.forename: Naoko
authors.initials: N
authors.lastname: Koike
authors.forename: Thomas
authors.initials: T
authors.lastname: d'Arville
authors.forename: Peter
authors.initials: P
authors.lastname: Yeh
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ezzelarab
authors.forename: David
authors.initials: D
authors.lastname: Ayares
authors.forename: Mark
authors.initials: M
authors.lastname: Yazer
authors.forename: David K C
authors.initials: DK
authors.lastname: Cooper
mesh_terms: D000017:ABO Blood-Group System / Q000097:blood / Q000276:immunology; D000818:Animals; D001803:Blood Transfusion / Q000379:methods*; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D005700:Galactosyltransferases / Q000235:genetics / Q000502:physiology; D006384:Hemagglutination / Q000502:physiology; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D011485:Protein Binding; D013552:Swine
chemical_list: D000017:ABO Blood-Group System; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D005700:Galactosyltransferases; C047006:N-acetyllactosaminide alpha-1,3-galactosyltransferase